From 77161de4546697f9bf2da6d081eeba4c399b3313 Mon Sep 17 00:00:00 2001 From: Graham Christensen Date: Tue, 1 May 2018 19:54:21 -0400 Subject: nixpkgs docs: format =) --- doc/stdenv.xml | 4149 +++++++++++++++++++++++++++++++------------------------- 1 file changed, 2311 insertions(+), 1838 deletions(-) (limited to 'doc/stdenv.xml') diff --git a/doc/stdenv.xml b/doc/stdenv.xml index 2a3316b8d018..d5028c51cd51 100644 --- a/doc/stdenv.xml +++ b/doc/stdenv.xml @@ -1,27 +1,24 @@ - -The Standard Environment - - -The standard build environment in the Nix Packages collection -provides an environment for building Unix packages that does a lot of -common build tasks automatically. In fact, for Unix packages that use -the standard ./configure; make; make install build -interface, you don’t need to write a build script at all; the standard -environment does everything automatically. If -stdenv doesn’t do what you need automatically, you -can easily customise or override the various build phases. - - -
Using -<literal>stdenv</literal> - -To build a package with the standard environment, you use the -function stdenv.mkDerivation, instead of the -primitive built-in function derivation, e.g. - + The Standard Environment + + The standard build environment in the Nix Packages collection provides an + environment for building Unix packages that does a lot of common build tasks + automatically. In fact, for Unix packages that use the standard + ./configure; make; make install build interface, you + don’t need to write a build script at all; the standard environment does + everything automatically. If stdenv doesn’t do what you + need automatically, you can easily customise or override the various build + phases. + +
+ Using <literal>stdenv</literal> + + + To build a package with the standard environment, you use the function + stdenv.mkDerivation, instead of the primitive built-in + function derivation, e.g. stdenv.mkDerivation { name = "libfoo-1.2.3"; @@ -30,39 +27,35 @@ stdenv.mkDerivation { sha256 = "0x2g1jqygyr5wiwg4ma1nd7w4ydpy82z9gkcv8vh2v8dn3y58v5m"; }; } - -(stdenv needs to be in scope, so if you write this -in a separate Nix expression from -pkgs/all-packages.nix, you need to pass it as a -function argument.) Specifying a name and a -src is the absolute minimum you need to do. Many -packages have dependencies that are not provided in the standard -environment. It’s usually sufficient to specify those dependencies in -the buildInputs attribute: - + (stdenv needs to be in scope, so if you write this in a + separate Nix expression from pkgs/all-packages.nix, you + need to pass it as a function argument.) Specifying a + name and a src is the absolute minimum + you need to do. Many packages have dependencies that are not provided in the + standard environment. It’s usually sufficient to specify those + dependencies in the buildInputs attribute: stdenv.mkDerivation { name = "libfoo-1.2.3"; ... buildInputs = [libbar perl ncurses]; } - -This attribute ensures that the bin -subdirectories of these packages appear in the PATH -environment variable during the build, that their -include subdirectories are searched by the C -compiler, and so on. (See for -details.) - -Often it is necessary to override or modify some aspect of the -build. To make this easier, the standard environment breaks the -package build into a number of phases, all of -which can be overridden or modified individually: unpacking the -sources, applying patches, configuring, building, and installing. -(There are some others; see .) -For instance, a package that doesn’t supply a makefile but instead has -to be compiled “manually” could be handled like this: - + This attribute ensures that the bin subdirectories of + these packages appear in the PATH environment variable during + the build, that their include subdirectories are + searched by the C compiler, and so on. (See + for details.) + + + + Often it is necessary to override or modify some aspect of the build. To + make this easier, the standard environment breaks the package build into a + number of phases, all of which can be overridden or + modified individually: unpacking the sources, applying patches, configuring, + building, and installing. (There are some others; see + .) For instance, a package that doesn’t + supply a makefile but instead has to be compiled “manually” could be + handled like this: stdenv.mkDerivation { name = "fnord-4.5"; @@ -75,35 +68,33 @@ stdenv.mkDerivation { cp foo $out/bin ''; } - -(Note the use of ''-style string literals, which -are very convenient for large multi-line script fragments because they -don’t need escaping of " and \, -and because indentation is intelligently removed.) - -There are many other attributes to customise the build. These -are listed in . - -While the standard environment provides a generic builder, you -can still supply your own build script: - + (Note the use of ''-style string literals, which are very + convenient for large multi-line script fragments because they don’t need + escaping of " and \, and because + indentation is intelligently removed.) + + + + There are many other attributes to customise the build. These are listed in + . + + + + While the standard environment provides a generic builder, you can still + supply your own build script: stdenv.mkDerivation { name = "libfoo-1.2.3"; ... builder = ./builder.sh; } - -where the builder can do anything it wants, but typically starts with - + where the builder can do anything it wants, but typically starts with source $stdenv/setup - -to let stdenv set up the environment (e.g., process -the buildInputs). If you want, you can still use -stdenv’s generic builder: - + to let stdenv set up the environment (e.g., process the + buildInputs). If you want, you can still use + stdenv’s generic builder: source $stdenv/setup @@ -119,116 +110,186 @@ installPhase() { genericBuild - - - -
- - -
Tools provided by -<literal>stdenv</literal> - -The standard environment provides the following packages: - - - - The GNU C Compiler, configured with C and C++ - support. - - GNU coreutils (contains a few dozen standard Unix - commands). - - GNU findutils (contains - find). - - GNU diffutils (contains diff, - cmp). - - GNU sed. - - GNU grep. - - GNU awk. - - GNU tar. - - gzip, bzip2 - and xz. - - GNU Make. It has been patched to provide - nested output that can be fed into the - nix-log2xml command and - log2html stylesheet to create a structured, - readable output of the build steps performed by - Make. - - Bash. This is the shell used for all builders in - the Nix Packages collection. Not using /bin/sh - removes a large source of portability problems. - - The patch - command. - - - - - -On Linux, stdenv also includes the -patchelf utility. - -
- - -
Specifying dependencies - - - As described in the Nix manual, almost any *.drv store path in a derivation's attribute set will induce a dependency on that derivation. - mkDerivation, however, takes a few attributes intended to, between them, include all the dependencies of a package. - This is done both for structure and consistency, but also so that certain other setup can take place. - For example, certain dependencies need their bin directories added to the PATH. - That is built-in, but other setup is done via a pluggable mechanism that works in conjunction with these dependency attributes. - See for details. - - - Dependencies can be broken down along three axes: their host and target platforms relative to the new derivation's, and whether they are propagated. - The platform distinctions are motivated by cross compilation; see for exactly what each platform means. - - The build platform is ignored because it is a mere implementation detail of the package satisfying the dependency: - As a general programming principle, dependencies are always specified as interfaces, not concrete implementation. - - But even if one is not cross compiling, the platforms imply whether or not the dependency is needed at run-time or build-time, a concept that makes perfect sense outside of cross compilation. - For now, the run-time/build-time distinction is just a hint for mental clarity, but in the future it perhaps could be enforced. - - - The extension of PATH with dependencies, alluded to above, proceeds according to the relative platforms alone. - The process is carried out only for dependencies whose host platform matches the new derivation's build platform–i.e. which run on the platform where the new derivation will be built. - - Currently, that means for native builds all dependencies are put on the PATH. - But in the future that may not be the case for sake of matching cross: - the platforms would be assumed to be unique for native and cross builds alike, so only the depsBuild* and nativeBuildDependencies dependencies would affect the PATH. - - For each dependency dep of those dependencies, dep/bin, if present, is added to the PATH environment variable. - - - The dependency is propagated when it forces some of its other-transitive (non-immediate) downstream dependencies to also take it on as an immediate dependency. - Nix itself already takes a package's transitive dependencies into account, but this propagation ensures nixpkgs-specific infrastructure like setup hooks (mentioned above) also are run as if the propagated dependency. - - - It is important to note dependencies are not necessary propagated as the same sort of dependency that they were before, but rather as the corresponding sort so that the platform rules still line up. - The exact rules for dependency propagation can be given by assigning each sort of dependency two integers based one how it's host and target platforms are offset from the depending derivation's platforms. - Those offsets are given are given below in the descriptions of each dependency list attribute. - Algorithmically, we traverse propagated inputs, accumulating every propagated dep's propagated deps and adjusting them to account for the "shift in perspective" described by the current dep's platform offsets. - This results in sort a transitive closure of the dependency relation, with the offsets being approximately summed when two dependency links are combined. - We also prune transitive deps whose combined offsets go out-of-bounds, which can be viewed as a filter over that transitive closure removing dependencies that are blatantly absurd. - - - We can define the process precisely with Natural Deduction using the inference rules. - This probably seems a bit obtuse, but so is the bash code that actually implements it! - - The findInputs function, currently residing in pkgs/stdenv/generic/setup.sh, implements the propagation logic. - - They're confusing in very different ways so...hopefully if something doesn't make sense in one presentation, it does in the other! - + +
+
+ Tools provided by <literal>stdenv</literal> + + + The standard environment provides the following packages: + + + + The GNU C Compiler, configured with C and C++ support. + + + + + GNU coreutils (contains a few dozen standard Unix commands). + + + + + GNU findutils (contains find). + + + + + GNU diffutils (contains diff, cmp). + + + + + GNU sed. + + + + + GNU grep. + + + + + GNU awk. + + + + + GNU tar. + + + + + gzip, bzip2 and + xz. + + + + + GNU Make. It has been patched to provide nested output + that can be fed into the nix-log2xml command and + log2html stylesheet to create a structured, readable + output of the build steps performed by Make. + + + + + Bash. This is the shell used for all builders in the Nix Packages + collection. Not using /bin/sh removes a large source + of portability problems. + + + + + The patch command. + + + + + + + On Linux, stdenv also includes the + patchelf utility. + +
+
+ Specifying dependencies + + + As described in the Nix manual, almost any *.drv store + path in a derivation's attribute set will induce a dependency on that + derivation. mkDerivation, however, takes a few attributes + intended to, between them, include all the dependencies of a package. This + is done both for structure and consistency, but also so that certain other + setup can take place. For example, certain dependencies need their bin + directories added to the PATH. That is built-in, but other + setup is done via a pluggable mechanism that works in conjunction with these + dependency attributes. See for details. + + + + Dependencies can be broken down along three axes: their host and target + platforms relative to the new derivation's, and whether they are propagated. + The platform distinctions are motivated by cross compilation; see + for exactly what each platform means. + + + The build platform is ignored because it is a mere implementation detail + of the package satisfying the dependency: As a general programming + principle, dependencies are always specified as + interfaces, not concrete implementation. + + + But even if one is not cross compiling, the platforms imply whether or not + the dependency is needed at run-time or build-time, a concept that makes + perfect sense outside of cross compilation. For now, the run-time/build-time + distinction is just a hint for mental clarity, but in the future it perhaps + could be enforced. + + + + The extension of PATH with dependencies, alluded to above, + proceeds according to the relative platforms alone. The process is carried + out only for dependencies whose host platform matches the new derivation's + build platform–i.e. which run on the platform where the new derivation + will be built. + + + Currently, that means for native builds all dependencies are put on the + PATH. But in the future that may not be the case for sake + of matching cross: the platforms would be assumed to be unique for native + and cross builds alike, so only the depsBuild* and + nativeBuildDependencies dependencies would affect the + PATH. + + + For each dependency dep of those dependencies, + dep/bin, if present, is + added to the PATH environment variable. + + + + The dependency is propagated when it forces some of its other-transitive + (non-immediate) downstream dependencies to also take it on as an immediate + dependency. Nix itself already takes a package's transitive dependencies + into account, but this propagation ensures nixpkgs-specific infrastructure + like setup hooks (mentioned above) also are run as if the propagated + dependency. + + + + It is important to note dependencies are not necessary propagated as the + same sort of dependency that they were before, but rather as the + corresponding sort so that the platform rules still line up. The exact rules + for dependency propagation can be given by assigning each sort of dependency + two integers based one how it's host and target platforms are offset from + the depending derivation's platforms. Those offsets are given are given + below in the descriptions of each dependency list attribute. + Algorithmically, we traverse propagated inputs, accumulating every + propagated dep's propagated deps and adjusting them to account for the + "shift in perspective" described by the current dep's platform offsets. This + results in sort a transitive closure of the dependency relation, with the + offsets being approximately summed when two dependency links are combined. + We also prune transitive deps whose combined offsets go out-of-bounds, which + can be viewed as a filter over that transitive closure removing dependencies + that are blatantly absurd. + + + + We can define the process precisely with + Natural + Deduction using the inference rules. This probably seems a bit + obtuse, but so is the bash code that actually implements it! + + + The findInputs function, currently residing in + pkgs/stdenv/generic/setup.sh, implements the + propagation logic. + + + They're confusing in very different ways so...hopefully if something doesn't + make sense in one presentation, it does in the other! + let mapOffset(h, t, i) = i + (if i <= 0 then h else t - 1) propagated-dep(h0, t0, A, B) @@ -239,7 +300,7 @@ h0 + t1 in {-1, 0, 1} propagated-dep(mapOffset(h0, t0, h1), mapOffset(h0, t0, t1), A, C) - + let mapOffset(h, t, i) = i + (if i <= 0 then h else t - 1) dep(h0, _, A, B) @@ -250,1139 +311,1450 @@ h0 + t1 in {-1, 0, -1} propagated-dep(mapOffset(h0, t0, h1), mapOffset(h0, t0, t1), A, C) - + propagated-dep(h, t, A, B) -------------------------------------- Propagated deps count as deps dep(h, t, A, B) - Some explanation of this monstrosity is in order. - In the common case, the target offset of a dependency is the successor to the target offset: t = h + 1. - That means that: - + Some explanation of this monstrosity is in order. In the common case, the + target offset of a dependency is the successor to the target offset: + t = h + 1. That means that: + let f(h, t, i) = i + (if i <= 0 then h else t - 1) let f(h, h + 1, i) = i + (if i <= 0 then h else (h + 1) - 1) let f(h, h + 1, i) = i + (if i <= 0 then h else h) let f(h, h + 1, i) = i + h - This is where the "sum-like" comes from above: - We can just sum all the host offset to get the host offset of the transitive dependency. - The target offset is the transitive dep is simply the host offset + 1, just as it was with the dependencies composed to make this transitive one; - it can be ignored as it doesn't add any new information. - - - Because of the bounds checks, the uncommon cases are h = t and h + 2 = t. - In the former case, the motivation for mapOffset is that since its host and target platforms are the same, no transitive dep of it should be able to "discover" an offset greater than its reduced target offsets. - mapOffset effectively "squashes" all its transitive dependencies' offsets so that none will ever be greater than the target offset of the original h = t package. - In the other case, h + 1 is skipped over between the host and target offsets. - Instead of squashing the offsets, we need to "rip" them apart so no transitive dependencies' offset is that one. - - -Overall, the unifying theme here is that propagation shouldn't be introducing transitive dependencies involving platforms the needing package is unaware of. -The offset bounds checking and definition of mapOffset together ensure that this is the case. -Discovering a new offset is discovering a new platform, and since those platforms weren't in the derivation "spec" of the needing package, they cannot be relevant. -From a capability perspective, we can imagine that the host and target platforms of a package are the capabilities a package requires, and the depending package must provide the capability to the dependency. - - - - Variables specifying dependencies - + This is where the "sum-like" comes from above: We can just sum all the host + offset to get the host offset of the transitive dependency. The target + offset is the transitive dep is simply the host offset + 1, just as it was + with the dependencies composed to make this transitive one; it can be + ignored as it doesn't add any new information. + + + + Because of the bounds checks, the uncommon cases are h = + t and h + 2 = t. In the former case, the + motivation for mapOffset is that since its host and + target platforms are the same, no transitive dep of it should be able to + "discover" an offset greater than its reduced target offsets. + mapOffset effectively "squashes" all its transitive + dependencies' offsets so that none will ever be greater than the target + offset of the original h = t package. In the other case, + h + 1 is skipped over between the host and target + offsets. Instead of squashing the offsets, we need to "rip" them apart so no + transitive dependencies' offset is that one. + + + + Overall, the unifying theme here is that propagation shouldn't be + introducing transitive dependencies involving platforms the needing package + is unaware of. The offset bounds checking and definition of + mapOffset together ensure that this is the case. + Discovering a new offset is discovering a new platform, and since those + platforms weren't in the derivation "spec" of the needing package, they + cannot be relevant. From a capability perspective, we can imagine that the + host and target platforms of a package are the capabilities a package + requires, and the depending package must provide the capability to the + dependency. + + + + Variables specifying dependencies - depsBuildBuild - - - A list of dependencies whose host and target platforms are the new derivation's build platform. - This means a -1 host and -1 target offset from the new derivation's platforms. - They are programs/libraries used at build time that furthermore produce programs/libraries also used at build time. - If the dependency doesn't care about the target platform (i.e. isn't a compiler or similar tool), put it in nativeBuildInputsinstead. - The most common use for this buildPackages.stdenv.cc, the default C compiler for this role. - That example crops up more than one might think in old commonly used C libraries. - - - Since these packages are able to be run at build time, that are always added to the PATH, as described above. - But since these packages are only guaranteed to be able to run then, they shouldn't persist as run-time dependencies. - This isn't currently enforced, but could be in the future. - - - - - - nativeBuildInputs + depsBuildBuild + - - A list of dependencies whose host platform is the new derivation's build platform, and target platform is the new derivation's host platform. - This means a -1 host offset and 0 target offset from the new derivation's platforms. - They are programs/libraries used at build time that, if they are a compiler or similar tool, produce code to run at run time—i.e. tools used to build the new derivation. - If the dependency doesn't care about the target platform (i.e. isn't a compiler or similar tool), put it here, rather than in depsBuildBuild or depsBuildTarget. - This would be called depsBuildHost but for historical continuity. - - - Since these packages are able to be run at build time, that are added to the PATH, as described above. - But since these packages only are guaranteed to be able to run then, they shouldn't persist as run-time dependencies. - This isn't currently enforced, but could be in the future. - + + A list of dependencies whose host and target platforms are the new + derivation's build platform. This means a -1 host and + -1 target offset from the new derivation's platforms. + They are programs/libraries used at build time that furthermore produce + programs/libraries also used at build time. If the dependency doesn't + care about the target platform (i.e. isn't a compiler or similar tool), + put it in nativeBuildInputsinstead. The most common + use for this buildPackages.stdenv.cc, the default C + compiler for this role. That example crops up more than one might think + in old commonly used C libraries. + + + Since these packages are able to be run at build time, that are always + added to the PATH, as described above. But since these + packages are only guaranteed to be able to run then, they shouldn't + persist as run-time dependencies. This isn't currently enforced, but + could be in the future. + - - - - depsBuildTarget + + + nativeBuildInputs + - - A list of dependencies whose host platform is the new derivation's build platform, and target platform is the new derivation's target platform. - This means a -1 host offset and 1 target offset from the new derivation's platforms. - They are programs used at build time that produce code to run at run with code produced by the depending package. - Most commonly, these would tools used to build the runtime or standard library the currently-being-built compiler will inject into any code it compiles. - In many cases, the currently-being built compiler is itself employed for that task, but when that compiler won't run (i.e. its build and host platform differ) this is not possible. - Other times, the compiler relies on some other tool, like binutils, that is always built separately so the dependency is unconditional. - - - This is a somewhat confusing dependency to wrap ones head around, and for good reason. - As the only one where the platform offsets are not adjacent integers, it requires thinking of a bootstrapping stage two away from the current one. - It and it's use-case go hand in hand and are both considered poor form: - try not to need this sort dependency, and try not avoid building standard libraries / runtimes in the same derivation as the compiler produces code using them. - Instead strive to build those like a normal library, using the newly-built compiler just as a normal library would. - In short, do not use this attribute unless you are packaging a compiler and are sure it is needed. + + A list of dependencies whose host platform is the new derivation's build + platform, and target platform is the new derivation's host platform. This + means a -1 host offset and 0 target + offset from the new derivation's platforms. They are programs/libraries + used at build time that, if they are a compiler or similar tool, produce + code to run at run time—i.e. tools used to build the new derivation. If + the dependency doesn't care about the target platform (i.e. isn't a + compiler or similar tool), put it here, rather than in + depsBuildBuild or depsBuildTarget. + This would be called depsBuildHost but for historical + continuity. - Since these packages are able to be run at build time, that are added to the PATH, as described above. - But since these packages only are guaranteed to be able to run then, they shouldn't persist as run-time dependencies. - This isn't currently enforced, but could be in the future. + Since these packages are able to be run at build time, that are added to + the PATH, as described above. But since these packages + only are guaranteed to be able to run then, they shouldn't persist as + run-time dependencies. This isn't currently enforced, but could be in the + future. - - - - depsHostHost - - A list of dependencies whose host and target platforms match the new derivation's host platform. - This means a both 0 host offset and 0 target offset from the new derivation's host platform. - These are packages used at run-time to generate code also used at run-time. - In practice, that would usually be tools used by compilers for metaprogramming/macro systems, or libraries used by the macros/metaprogramming code itself. - It's always preferable to use a depsBuildBuild dependency in the derivation being built than a depsHostHost on the tool doing the building for this purpose. - - - - - buildInputs + + + depsBuildTarget + - - A list of dependencies whose host platform and target platform match the new derivation's. - This means a 0 host offset and 1 target offset from the new derivation's host platform. - This would be called depsHostTarget but for historical continuity. - If the dependency doesn't care about the target platform (i.e. isn't a compiler or similar tool), put it here, rather than in depsBuildBuild. - - - These often are programs/libraries used by the new derivation at run-time, but that isn't always the case. - For example, the machine code in a statically linked library is only used at run time, but the derivation containing the library is only needed at build time. - Even in the dynamic case, the library may also be needed at build time to appease the linker. - + + A list of dependencies whose host platform is the new derivation's build + platform, and target platform is the new derivation's target platform. + This means a -1 host offset and 1 + target offset from the new derivation's platforms. They are programs used + at build time that produce code to run at run with code produced by the + depending package. Most commonly, these would tools used to build the + runtime or standard library the currently-being-built compiler will + inject into any code it compiles. In many cases, the currently-being + built compiler is itself employed for that task, but when that compiler + won't run (i.e. its build and host platform differ) this is not possible. + Other times, the compiler relies on some other tool, like binutils, that + is always built separately so the dependency is unconditional. + + + This is a somewhat confusing dependency to wrap ones head around, and for + good reason. As the only one where the platform offsets are not adjacent + integers, it requires thinking of a bootstrapping stage + two away from the current one. It and it's use-case + go hand in hand and are both considered poor form: try not to need this + sort dependency, and try not avoid building standard libraries / runtimes + in the same derivation as the compiler produces code using them. Instead + strive to build those like a normal library, using the newly-built + compiler just as a normal library would. In short, do not use this + attribute unless you are packaging a compiler and are sure it is needed. + + + Since these packages are able to be run at build time, that are added to + the PATH, as described above. But since these packages + only are guaranteed to be able to run then, they shouldn't persist as + run-time dependencies. This isn't currently enforced, but could be in the + future. + - - - - depsTargetTarget - - A list of dependencies whose host platform matches the new derivation's target platform. - This means a 1 offset from the new derivation's platforms. - These are packages that run on the target platform, e.g. the standard library or run-time deps of standard library that a compiler insists on knowing about. - It's poor form in almost all cases for a package to depend on another from a future stage [future stage corresponding to positive offset]. - Do not use this attribute unless you are packaging a compiler and are sure it is needed. - - - - - depsBuildBuildPropagated - - The propagated equivalent of depsBuildBuild. - This perhaps never ought to be used, but it is included for consistency [see below for the others]. - - - - - propagatedNativeBuildInputs - - The propagated equivalent of nativeBuildInputs. - This would be called depsBuildHostPropagated but for historical continuity. - For example, if package Y has propagatedNativeBuildInputs = [X], and package Z has buildInputs = [Y], then package Z will be built as if it included package X in its nativeBuildInputs. - If instead, package Z has nativeBuildInputs = [Y], then Z will be built as if it included X in the depsBuildBuild of package Z, because of the sum of the two -1 host offsets. - - - - - depsBuildTargetPropagated - - The propagated equivalent of depsBuildTarget. - This is prefixed for the same reason of alerting potential users. - - - - - depsHostHostPropagated - - The propagated equivalent of depsHostHost. - - - - - propagatedBuildInputs - - The propagated equivalent of buildInputs. - This would be called depsHostTargetPropagated but for historical continuity. - - - - - depsTargetTarget - - The propagated equivalent of depsTargetTarget. - This is prefixed for the same reason of alerting potential users. - - - - - -
- - -
Attributes - - - Variables affecting <literal>stdenv</literal> - initialisation - - - NIX_DEBUG - - A natural number indicating how much information to log. - If set to 1 or higher, stdenv will print moderate debug information during the build. - In particular, the gcc and ld wrapper scripts will print out the complete command line passed to the wrapped tools. - If set to 6 or higher, the stdenv setup script will be run with set -x tracing. - If set to 7 or higher, the gcc and ld wrapper scripts will also be run with set -x tracing. - - - - - - - Variables affecting build properties - - - enableParallelBuilding + + + depsHostHost + - If set to true, stdenv will - pass specific flags to make and other build tools to - enable parallel building with up to build-cores - workers. - - Unless set to false, some build systems with good - support for parallel building including cmake, - meson, and qmake will set it to - true. + + A list of dependencies whose host and target platforms match the new + derivation's host platform. This means a both 0 host + offset and 0 target offset from the new derivation's + host platform. These are packages used at run-time to generate code also + used at run-time. In practice, that would usually be tools used by + compilers for metaprogramming/macro systems, or libraries used by the + macros/metaprogramming code itself. It's always preferable to use a + depsBuildBuild dependency in the derivation being + built than a depsHostHost on the tool doing the + building for this purpose. + - - - - preferLocalBuild - If set, specifies that the package is so lightweight - in terms of build operations (e.g. write a text file from a Nix string - to the store) that there's no need to look for it in binary caches -- - it's faster to just build it locally. It also tells Hydra and other - facilities that this package doesn't need to be exported in binary - caches (noone would use it, after all). - - - - - - Special variables - - - passthru - This is an attribute set which can be filled with arbitrary - values. For example: - - -passthru = { - foo = "bar"; - baz = { - value1 = 4; - value2 = 5; - }; -} - - - - - Values inside it are not passed to the builder, so you can change - them without triggering a rebuild. However, they can be accessed outside of a - derivation directly, as if they were set inside a derivation itself, e.g. - hello.baz.value1. We don't specify any usage or - schema of passthru - it is meant for values that would be - useful outside the derivation in other parts of a Nix expression (e.g. in other - derivations). An example would be to convey some specific dependency of your - derivation which contains a program with plugins support. Later, others who - make derivations with plugins can use passed-through dependency to ensure that - their plugin would be binary-compatible with built program. - - - - -
- - -
Phases - -The generic builder has a number of phases. -Package builds are split into phases to make it easier to override -specific parts of the build (e.g., unpacking the sources or installing -the binaries). Furthermore, it allows a nicer presentation of build -logs in the Nix build farm. - -Each phase can be overridden in its entirety either by setting -the environment variable -namePhase to a string -containing some shell commands to be executed, or by redefining the -shell function -namePhase. The former -is convenient to override a phase from the derivation, while the -latter is convenient from a build script. - -However, typically one only wants to add some -commands to a phase, e.g. by defining postInstall -or preFixup, as skipping some of the default actions -may have unexpected consequences. - - - -
Controlling -phases - -There are a number of variables that control what phases are -executed and in what order: - - - Variables affecting phase control - - - phases + + + buildInputs + - Specifies the phases. You can change the order in which - phases are executed, or add new phases, by setting this - variable. If it’s not set, the default value is used, which is - $prePhases unpackPhase patchPhase $preConfigurePhases - configurePhase $preBuildPhases buildPhase checkPhase - $preInstallPhases installPhase fixupPhase $preDistPhases - distPhase $postPhases. - - - Usually, if you just want to add a few phases, it’s more - convenient to set one of the variables below (such as - preInstallPhases), as you then don’t specify - all the normal phases. + + A list of dependencies whose host platform and target platform match the + new derivation's. This means a 0 host offset and + 1 target offset from the new derivation's host + platform. This would be called depsHostTarget but for + historical continuity. If the dependency doesn't care about the target + platform (i.e. isn't a compiler or similar tool), put it here, rather + than in depsBuildBuild. + + + These often are programs/libraries used by the new derivation at + run-time, but that isn't always the case. For + example, the machine code in a statically linked library is only used at + run time, but the derivation containing the library is only needed at + build time. Even in the dynamic case, the library may also be needed at + build time to appease the linker. + - - - - prePhases + + + depsTargetTarget + - Additional phases executed before any of the default phases. + + A list of dependencies whose host platform matches the new derivation's + target platform. This means a 1 offset from the new + derivation's platforms. These are packages that run on the target + platform, e.g. the standard library or run-time deps of standard library + that a compiler insists on knowing about. It's poor form in almost all + cases for a package to depend on another from a future stage [future + stage corresponding to positive offset]. Do not use this attribute unless + you are packaging a compiler and are sure it is needed. + - - - - preConfigurePhases + + + depsBuildBuildPropagated + - Additional phases executed just before the configure phase. + + The propagated equivalent of depsBuildBuild. This + perhaps never ought to be used, but it is included for consistency [see + below for the others]. + - - - - preBuildPhases + + + propagatedNativeBuildInputs + - Additional phases executed just before the build phase. + + The propagated equivalent of nativeBuildInputs. This + would be called depsBuildHostPropagated but for + historical continuity. For example, if package Y has + propagatedNativeBuildInputs = [X], and package + Z has buildInputs = [Y], then + package Z will be built as if it included package + X in its nativeBuildInputs. If + instead, package Z has nativeBuildInputs = + [Y], then Z will be built as if it included + X in the depsBuildBuild of package + Z, because of the sum of the two -1 + host offsets. + - - - - preInstallPhases + + + depsBuildTargetPropagated + - Additional phases executed just before the install phase. + + The propagated equivalent of depsBuildTarget. This is + prefixed for the same reason of alerting potential users. + - - - - preFixupPhases + + + depsHostHostPropagated + - Additional phases executed just before the fixup phase. + + The propagated equivalent of depsHostHost. + - - - - preDistPhases + + + propagatedBuildInputs + - Additional phases executed just before the distribution phase. + + The propagated equivalent of buildInputs. This would + be called depsHostTargetPropagated but for historical + continuity. + - - - - postPhases + + + depsTargetTarget + - Additional phases executed after any of the default - phases. + + The propagated equivalent of depsTargetTarget. This is + prefixed for the same reason of alerting potential users. + - - - - - - -
- - -
The unpack phase - -The unpack phase is responsible for unpacking the source code of -the package. The default implementation of -unpackPhase unpacks the source files listed in -the src environment variable to the current directory. -It supports the following files by default: - - - - - Tar files - These can optionally be compressed using - gzip (.tar.gz, - .tgz or .tar.Z), - bzip2 (.tar.bz2 or - .tbz2) or xz - (.tar.xz or - .tar.lzma). - - - - Zip files - Zip files are unpacked using - unzip. However, unzip is - not in the standard environment, so you should add it to - buildInputs yourself. - - - - Directories in the Nix store - These are simply copied to the current directory. - The hash part of the file name is stripped, - e.g. /nix/store/1wydxgby13cz...-my-sources - would be copied to - my-sources. - - - - -Additional file types can be supported by setting the -unpackCmd variable (see below). - - - - - Variables controlling the unpack phase - - - srcs / src - The list of source files or directories to be - unpacked or copied. One of these must be set. - - - - sourceRoot - After running unpackPhase, - the generic builder changes the current directory to the directory - created by unpacking the sources. If there are multiple source - directories, you should set sourceRoot to the - name of the intended directory. - - - - setSourceRoot - Alternatively to setting - sourceRoot, you can set - setSourceRoot to a shell command to be - evaluated by the unpack phase after the sources have been - unpacked. This command must set - sourceRoot. - - - - preUnpack - Hook executed at the start of the unpack - phase. - - - - postUnpack - Hook executed at the end of the unpack - phase. - - - - dontMakeSourcesWritable - If set to 1, the unpacked - sources are not made - writable. By default, they are made writable to prevent problems - with read-only sources. For example, copied store directories - would be read-only without this. - - - - unpackCmd - The unpack phase evaluates the string - $unpackCmd for any unrecognised file. The path - to the current source file is contained in the - curSrc variable. - - - - -
- - -
The patch phase - -The patch phase applies the list of patches defined in the -patches variable. - - - Variables controlling the patch phase - - - patches - The list of patches. They must be in the format - accepted by the patch command, and may - optionally be compressed using gzip - (.gz), bzip2 - (.bz2) or xz - (.xz). - - - - patchFlags - Flags to be passed to patch. - If not set, the argument is used, which - causes the leading directory component to be stripped from the - file names in each patch. - - - - prePatch - Hook executed at the start of the patch - phase. - - - - postPatch - Hook executed at the end of the patch - phase. - - - - -
- - -
The configure phase - -The configure phase prepares the source tree for building. The -default configurePhase runs -./configure (typically an Autoconf-generated -script) if it exists. - - - Variables controlling the configure phase - - - configureScript - The name of the configure script. It defaults to - ./configure if it exists; otherwise, the - configure phase is skipped. This can actually be a command (like - perl ./Configure.pl). - - - - configureFlags - A list of strings passed as additional arguments to the - configure script. - - - - configureFlagsArray - A shell array containing additional arguments - passed to the configure script. You must use this instead of - configureFlags if the arguments contain - spaces. - - - - dontAddPrefix - By default, the flag - --prefix=$prefix is added to the configure - flags. If this is undesirable, set this variable to - true. - - - - prefix - The prefix under which the package must be - installed, passed via the option to the - configure script. It defaults to - . - - - - dontAddDisableDepTrack - By default, the flag - --disable-dependency-tracking is added to the - configure flags to speed up Automake-based builds. If this is - undesirable, set this variable to true. - - - - dontFixLibtool - By default, the configure phase applies some - special hackery to all files called ltmain.sh - before running the configure script in order to improve the purity - of Libtool-based packagesIt clears the - sys_lib_*search_path - variables in the Libtool script to prevent Libtool from using - libraries in /usr/lib and - such.. If this is undesirable, set this - variable to true. - - - - dontDisableStatic - By default, when the configure script has - , the option - is added to the configure flags. - If this is undesirable, set this variable to - true. - - - - configurePlatforms - - By default, when cross compiling, the configure script has and passed. - Packages can instead pass [ "build" "host" "target" ] or a subset to control exactly which platform flags are passed. - Compilers and other tools should use this to also pass the target platform, for example. - Eventually these will be passed when in native builds too, to improve determinism: build-time guessing, as is done today, is a risk of impurity. - - - - - preConfigure - Hook executed at the start of the configure - phase. - - - - postConfigure - Hook executed at the end of the configure - phase. - - - - - -
- - -
The build phase - -The build phase is responsible for actually building the package -(e.g. compiling it). The default buildPhase -simply calls make if a file named -Makefile, makefile or -GNUmakefile exists in the current directory (or -the makefile is explicitly set); otherwise it does -nothing. - - - Variables controlling the build phase - - - dontBuild - Set to true to skip the build phase. - - - - makefile - The file name of the Makefile. - - - - makeFlags - A list of strings passed as additional flags to - make. These flags are also used by the default - install and check phase. For setting make flags specific to the - build phase, use buildFlags (see below). - - -makeFlags = [ "PREFIX=$(out)" ]; - - - The flags are quoted in bash, but environment variables can - be specified by using the make syntax. - - - - makeFlagsArray - A shell array containing additional arguments - passed to make. You must use this instead of - makeFlags if the arguments contain - spaces, e.g. - - -makeFlagsArray=(CFLAGS="-O0 -g" LDFLAGS="-lfoo -lbar") - - - Note that shell arrays cannot be passed through environment - variables, so you cannot set makeFlagsArray in - a derivation attribute (because those are passed through - environment variables): you have to define them in shell - code. - - - - buildFlags / buildFlagsArray - A list of strings passed as additional flags to - make. Like makeFlags and - makeFlagsArray, but only used by the build - phase. - - - - preBuild - Hook executed at the start of the build - phase. - - - - postBuild - Hook executed at the end of the build - phase. - - - - - - -You can set flags for make through the -makeFlags variable. - -Before and after running make, the hooks -preBuild and postBuild are -called, respectively. - -
- - -
The check phase - -The check phase checks whether the package was built correctly -by running its test suite. The default -checkPhase calls make check, -but only if the doCheck variable is enabled. - - - Variables controlling the check phase - - - doCheck - - Controls whether the check phase is executed. - By default it is skipped, but if doCheck is set to true, the check phase is usually executed. - Thus you should set doCheck = true; in the derivation to enable checks. - The exception is cross compilation. - Cross compiled builds never run tests, no matter how doCheck is set, - as the newly-built program won't run on the platform used to build it. - - - - - makeFlags / - makeFlagsArray / - makefile - See the build phase for details. - - - - checkTarget - The make target that runs the tests. Defaults to - check. - - - - checkFlags / checkFlagsArray - A list of strings passed as additional flags to - make. Like makeFlags and - makeFlagsArray, but only used by the check - phase. - - - - preCheck - Hook executed at the start of the check - phase. - - - - postCheck - Hook executed at the end of the check - phase. - - - - - -
- - -
The install phase - -The install phase is responsible for installing the package in -the Nix store under out. The default -installPhase creates the directory -$out and calls make -install. - - - Variables controlling the install phase - - - makeFlags / - makeFlagsArray / - makefile - See the build phase for details. - - - - installTargets - The make targets that perform the installation. - Defaults to install. Example: - - -installTargets = "install-bin install-doc"; + + +
+
+ Attributes + + + Variables affecting <literal>stdenv</literal> initialisation + + NIX_DEBUG + + + + A natural number indicating how much information to log. If set to 1 or + higher, stdenv will print moderate debug information + during the build. In particular, the gcc and + ld wrapper scripts will print out the complete command + line passed to the wrapped tools. If set to 6 or higher, the + stdenv setup script will be run with set + -x tracing. If set to 7 or higher, the gcc + and ld wrapper scripts will also be run with + set -x tracing. + + + + - - - - - installFlags / installFlagsArray - A list of strings passed as additional flags to - make. Like makeFlags and - makeFlagsArray, but only used by the install - phase. - - - - preInstall - Hook executed at the start of the install - phase. - - - - postInstall - Hook executed at the end of the install - phase. - - - - - -
- - -
The fixup phase - -The fixup phase performs some (Nix-specific) post-processing -actions on the files installed under $out by the -install phase. The default fixupPhase does the -following: - - - - It moves the man/, - doc/ and info/ - subdirectories of $out to - share/. - - It strips libraries and executables of debug - information. - - On Linux, it applies the patchelf - command to ELF executables and libraries to remove unused - directories from the RPATH in order to prevent - unnecessary runtime dependencies. - - It rewrites the interpreter paths of shell scripts - to paths found in PATH. E.g., - /usr/bin/perl will be rewritten to - /nix/store/some-perl/bin/perl - found in PATH. - - - - - - - Variables controlling the fixup phase - - - dontStrip - If set, libraries and executables are not - stripped. By default, they are. - - - dontStripHost - - Like dontStripHost, but only affects the strip command targetting the package's host platform. - Useful when supporting cross compilation, but otherwise feel free to ignore. - - - - dontStripTarget - - Like dontStripHost, but only affects the strip command targetting the packages' target platform. - Useful when supporting cross compilation, but otherwise feel free to ignore. - - - - - dontMoveSbin - If set, files in $out/sbin are not moved - to $out/bin. By default, they are. - - - - stripAllList - List of directories to search for libraries and - executables from which all symbols should be - stripped. By default, it’s empty. Stripping all symbols is - risky, since it may remove not just debug symbols but also ELF - information necessary for normal execution. - - - - stripAllFlags - Flags passed to the strip - command applied to the files in the directories listed in - stripAllList. Defaults to - (i.e. ). - - - - stripDebugList - List of directories to search for libraries and - executables from which only debugging-related symbols should be - stripped. It defaults to lib bin - sbin. - - - - stripDebugFlags - Flags passed to the strip - command applied to the files in the directories listed in - stripDebugList. Defaults to - - (i.e. ). - - - - dontPatchELF - If set, the patchelf command is - not used to remove unnecessary RPATH entries. - Only applies to Linux. - - - - dontPatchShebangs - If set, scripts starting with - #! do not have their interpreter paths - rewritten to paths in the Nix store. - - - - forceShare - The list of directories that must be moved from - $out to $out/share. - Defaults to man doc info. - - - - setupHook - A package can export a setup hook by setting this - variable. The setup hook, if defined, is copied to - $out/nix-support/setup-hook. Environment - variables are then substituted in it using substituteAll. - - - - preFixup - Hook executed at the start of the fixup - phase. - - - - postFixup - Hook executed at the end of the fixup - phase. - - - - separateDebugInfo - If set to true, the standard - environment will enable debug information in C/C++ builds. After - installation, the debug information will be separated from the - executables and stored in the output named - debug. (This output is enabled automatically; - you don’t need to set the outputs attribute - explicitly.) To be precise, the debug information is stored in - debug/lib/debug/.build-id/XX/YYYY…, - where XXYYYY… is the build - ID of the binary — a SHA-1 hash of the contents of - the binary. Debuggers like GDB use the build ID to look up the - separated debug information. - - For example, with GDB, you can add + + Variables affecting build properties + + enableParallelBuilding + + + + If set to true, stdenv will pass + specific flags to make and other build tools to enable + parallel building with up to build-cores workers. + + + Unless set to false, some build systems with good + support for parallel building including cmake, + meson, and qmake will set it to + true. + + + + + preferLocalBuild + + + + If set, specifies that the package is so lightweight in terms of build + operations (e.g. write a text file from a Nix string to the store) that + there's no need to look for it in binary caches -- it's faster to just + build it locally. It also tells Hydra and other facilities that this + package doesn't need to be exported in binary caches (noone would use it, + after all). + + + + + + Special variables + + passthru + + + + This is an attribute set which can be filled with arbitrary values. For + example: -set debug-file-directory ~/.nix-profile/lib/debug +passthru = { + foo = "bar"; + baz = { + value1 = 4; + value2 = 5; + }; +} - - to ~/.gdbinit. GDB will then be able to find - debug information installed via nix-env - -i. - + + + Values inside it are not passed to the builder, so you can change them + without triggering a rebuild. However, they can be accessed outside of a + derivation directly, as if they were set inside a derivation itself, e.g. + hello.baz.value1. We don't specify any usage or schema + of passthru - it is meant for values that would be + useful outside the derivation in other parts of a Nix expression (e.g. in + other derivations). An example would be to convey some specific + dependency of your derivation which contains a program with plugins + support. Later, others who make derivations with plugins can use + passed-through dependency to ensure that their plugin would be + binary-compatible with built program. + - - - - -
- -
The installCheck phase - -The installCheck phase checks whether the package was installed -correctly by running its test suite against the installed directories. -The default installCheck calls make -installcheck. - - - Variables controlling the installCheck phase - - - doInstallCheck - - Controls whether the installCheck phase is executed. - By default it is skipped, but if doInstallCheck is set to true, the installCheck phase is usually executed. - Thus you should set doInstallCheck = true; in the derivation to enable install checks. - The exception is cross compilation. - Cross compiled builds never run tests, no matter how doInstallCheck is set, - as the newly-built program won't run on the platform used to build it. - - - - - preInstallCheck - Hook executed at the start of the installCheck - phase. - - - - postInstallCheck - Hook executed at the end of the installCheck - phase. - - - - -
- -
The distribution -phase - -The distribution phase is intended to produce a source -distribution of the package. The default -distPhase first calls make -dist, then it copies the resulting source tarballs to -$out/tarballs/. This phase is only executed if -the attribute doDist is set. - - - Variables controlling the distribution phase - - - distTarget - The make target that produces the distribution. - Defaults to dist. - - - - distFlags / distFlagsArray - Additional flags passed to - make. - - - - tarballs - The names of the source distribution files to be - copied to $out/tarballs/. It can contain - shell wildcards. The default is - *.tar.gz. - - - - dontCopyDist - If set, no files are copied to - $out/tarballs/. - - - - preDist - Hook executed at the start of the distribution - phase. - - - - postDist - Hook executed at the end of the distribution - phase. - - - - - -
- - -
- - -
Shell functions - -The standard environment provides a number of useful -functions. - - - - - - makeWrapper - executable - wrapperfile - args - Constructs a wrapper for a program with various - possible arguments. For example: - + + +
+
+ Phases + + + The generic builder has a number of phases. Package + builds are split into phases to make it easier to override specific parts of + the build (e.g., unpacking the sources or installing the binaries). + Furthermore, it allows a nicer presentation of build logs in the Nix build + farm. + + + + Each phase can be overridden in its entirety either by setting the + environment variable namePhase + to a string containing some shell commands to be executed, or by redefining + the shell function namePhase. + The former is convenient to override a phase from the derivation, while the + latter is convenient from a build script. However, typically one only wants + to add some commands to a phase, e.g. by defining + postInstall or preFixup, as skipping + some of the default actions may have unexpected consequences. + + +
+ Controlling phases + + + There are a number of variables that control what phases are executed and + in what order: + + Variables affecting phase control + + phases + + + + Specifies the phases. You can change the order in which phases are + executed, or add new phases, by setting this variable. If it’s not + set, the default value is used, which is $prePhases + unpackPhase patchPhase $preConfigurePhases configurePhase + $preBuildPhases buildPhase checkPhase $preInstallPhases installPhase + fixupPhase $preDistPhases distPhase $postPhases. + + + Usually, if you just want to add a few phases, it’s more convenient + to set one of the variables below (such as + preInstallPhases), as you then don’t specify all + the normal phases. + + + + + prePhases + + + + Additional phases executed before any of the default phases. + + + + + preConfigurePhases + + + + Additional phases executed just before the configure phase. + + + + + preBuildPhases + + + + Additional phases executed just before the build phase. + + + + + preInstallPhases + + + + Additional phases executed just before the install phase. + + + + + preFixupPhases + + + + Additional phases executed just before the fixup phase. + + + + + preDistPhases + + + + Additional phases executed just before the distribution phase. + + + + + postPhases + + + + Additional phases executed after any of the default phases. + + + + + +
+ +
+ The unpack phase + + + The unpack phase is responsible for unpacking the source code of the + package. The default implementation of unpackPhase + unpacks the source files listed in the src environment + variable to the current directory. It supports the following files by + default: + + + Tar files + + + These can optionally be compressed using gzip + (.tar.gz, .tgz or + .tar.Z), bzip2 + (.tar.bz2 or .tbz2) or + xz (.tar.xz or + .tar.lzma). + + + + + Zip files + + + Zip files are unpacked using unzip. However, + unzip is not in the standard environment, so you + should add it to buildInputs yourself. + + + + + Directories in the Nix store + + + These are simply copied to the current directory. The hash part of the + file name is stripped, e.g. + /nix/store/1wydxgby13cz...-my-sources would be + copied to my-sources. + + + + + Additional file types can be supported by setting the + unpackCmd variable (see below). + + + + + + Variables controlling the unpack phase + + srcs / src + + + + The list of source files or directories to be unpacked or copied. One of + these must be set. + + + + + sourceRoot + + + + After running unpackPhase, the generic builder + changes the current directory to the directory created by unpacking the + sources. If there are multiple source directories, you should set + sourceRoot to the name of the intended directory. + + + + + setSourceRoot + + + + Alternatively to setting sourceRoot, you can set + setSourceRoot to a shell command to be evaluated by + the unpack phase after the sources have been unpacked. This command must + set sourceRoot. + + + + + preUnpack + + + + Hook executed at the start of the unpack phase. + + + + + postUnpack + + + + Hook executed at the end of the unpack phase. + + + + + dontMakeSourcesWritable + + + + If set to 1, the unpacked sources are + not made writable. By default, they are made + writable to prevent problems with read-only sources. For example, copied + store directories would be read-only without this. + + + + + unpackCmd + + + + The unpack phase evaluates the string $unpackCmd for + any unrecognised file. The path to the current source file is contained + in the curSrc variable. + + + + +
+ +
+ The patch phase + + + The patch phase applies the list of patches defined in the + patches variable. + + + + Variables controlling the patch phase + + patches + + + + The list of patches. They must be in the format accepted by the + patch command, and may optionally be compressed using + gzip (.gz), + bzip2 (.bz2) or + xz (.xz). + + + + + patchFlags + + + + Flags to be passed to patch. If not set, the argument + is used, which causes the leading directory + component to be stripped from the file names in each patch. + + + + + prePatch + + + + Hook executed at the start of the patch phase. + + + + + postPatch + + + + Hook executed at the end of the patch phase. + + + + +
+ +
+ The configure phase + + + The configure phase prepares the source tree for building. The default + configurePhase runs ./configure + (typically an Autoconf-generated script) if it exists. + + + + Variables controlling the configure phase + + configureScript + + + + The name of the configure script. It defaults to + ./configure if it exists; otherwise, the configure + phase is skipped. This can actually be a command (like perl + ./Configure.pl). + + + + + configureFlags + + + + A list of strings passed as additional arguments to the configure + script. + + + + + configureFlagsArray + + + + A shell array containing additional arguments passed to the configure + script. You must use this instead of configureFlags + if the arguments contain spaces. + + + + + dontAddPrefix + + + + By default, the flag --prefix=$prefix is added to the + configure flags. If this is undesirable, set this variable to true. + + + + + prefix + + + + The prefix under which the package must be installed, passed via the + option to the configure script. It defaults to + . + + + + + dontAddDisableDepTrack + + + + By default, the flag --disable-dependency-tracking is + added to the configure flags to speed up Automake-based builds. If this + is undesirable, set this variable to true. + + + + + dontFixLibtool + + + + By default, the configure phase applies some special hackery to all + files called ltmain.sh before running the configure + script in order to improve the purity of Libtool-based packages + + + It clears the + sys_lib_*search_path + variables in the Libtool script to prevent Libtool from using + libraries in /usr/lib and such. + + + . If this is undesirable, set this variable to true. + + + + + dontDisableStatic + + + + By default, when the configure script has + , the option + is added to the configure flags. + + + If this is undesirable, set this variable to true. + + + + + configurePlatforms + + + + By default, when cross compiling, the configure script has + and passed. + Packages can instead pass [ "build" "host" "target" ] + or a subset to control exactly which platform flags are passed. + Compilers and other tools should use this to also pass the target + platform, for example. + + + Eventually these will be passed when in native builds too, to improve + determinism: build-time guessing, as is done today, is a risk of + impurity. + + + + + + + preConfigure + + + + Hook executed at the start of the configure phase. + + + + + postConfigure + + + + Hook executed at the end of the configure phase. + + + + +
+ +
+ The build phase + + + The build phase is responsible for actually building the package (e.g. + compiling it). The default buildPhase simply calls + make if a file named Makefile, + makefile or GNUmakefile exists in + the current directory (or the makefile is explicitly + set); otherwise it does nothing. + + + + Variables controlling the build phase + + dontBuild + + + + Set to true to skip the build phase. + + + + + makefile + + + + The file name of the Makefile. + + + + + makeFlags + + + + A list of strings passed as additional flags to make. + These flags are also used by the default install and check phase. For + setting make flags specific to the build phase, use + buildFlags (see below). + +makeFlags = [ "PREFIX=$(out)" ]; + + + + The flags are quoted in bash, but environment variables can be + specified by using the make syntax. + + + + + + + makeFlagsArray + + + + A shell array containing additional arguments passed to + make. You must use this instead of + makeFlags if the arguments contain spaces, e.g. + +makeFlagsArray=(CFLAGS="-O0 -g" LDFLAGS="-lfoo -lbar") + + Note that shell arrays cannot be passed through environment variables, + so you cannot set makeFlagsArray in a derivation + attribute (because those are passed through environment variables): you + have to define them in shell code. + + + + + buildFlags / buildFlagsArray + + + + A list of strings passed as additional flags to make. + Like makeFlags and makeFlagsArray, + but only used by the build phase. + + + + + preBuild + + + + Hook executed at the start of the build phase. + + + + + postBuild + + + + Hook executed at the end of the build phase. + + + + + + + You can set flags for make through the + makeFlags variable. + + + + Before and after running make, the hooks + preBuild and postBuild are called, + respectively. + +
+ +
+ The check phase + + + The check phase checks whether the package was built correctly by running + its test suite. The default checkPhase calls + make check, but only if the doCheck + variable is enabled. + + + + Variables controlling the check phase + + doCheck + + + + Controls whether the check phase is executed. By default it is skipped, + but if doCheck is set to true, the check phase is + usually executed. Thus you should set +doCheck = true; + in the derivation to enable checks. The exception is cross compilation. + Cross compiled builds never run tests, no matter how + doCheck is set, as the newly-built program won't run + on the platform used to build it. + + + + + makeFlags / + makeFlagsArray / + makefile + + + + See the build phase for details. + + + + + checkTarget + + + + The make target that runs the tests. Defaults to + check. + + + + + checkFlags / checkFlagsArray + + + + A list of strings passed as additional flags to make. + Like makeFlags and makeFlagsArray, + but only used by the check phase. + + + + + preCheck + + + + Hook executed at the start of the check phase. + + + + + postCheck + + + + Hook executed at the end of the check phase. + + + + +
+ +
+ The install phase + + + The install phase is responsible for installing the package in the Nix + store under out. The default + installPhase creates the directory + $out and calls make install. + + + + Variables controlling the install phase + + makeFlags / + makeFlagsArray / + makefile + + + + See the build phase for details. + + + + + installTargets + + + + The make targets that perform the installation. Defaults to + install. Example: + +installTargets = "install-bin install-doc"; + + + + + installFlags / installFlagsArray + + + + A list of strings passed as additional flags to make. + Like makeFlags and makeFlagsArray, + but only used by the install phase. + + + + + preInstall + + + + Hook executed at the start of the install phase. + + + + + postInstall + + + + Hook executed at the end of the install phase. + + + + +
+ +
+ The fixup phase + + + The fixup phase performs some (Nix-specific) post-processing actions on the + files installed under $out by the install phase. The + default fixupPhase does the following: + + + + It moves the man/, doc/ and + info/ subdirectories of $out to + share/. + + + + + It strips libraries and executables of debug information. + + + + + On Linux, it applies the patchelf command to ELF + executables and libraries to remove unused directories from the + RPATH in order to prevent unnecessary runtime + dependencies. + + + + + It rewrites the interpreter paths of shell scripts to paths found in + PATH. E.g., /usr/bin/perl will be + rewritten to + /nix/store/some-perl/bin/perl + found in PATH. + + + + + + + Variables controlling the fixup phase + + dontStrip + + + + If set, libraries and executables are not stripped. By default, they + are. + + + + + dontStripHost + + + + Like dontStripHost, but only affects the + strip command targetting the package's host platform. + Useful when supporting cross compilation, but otherwise feel free to + ignore. + + + + + dontStripTarget + + + + Like dontStripHost, but only affects the + strip command targetting the packages' target + platform. Useful when supporting cross compilation, but otherwise feel + free to ignore. + + + + + dontMoveSbin + + + + If set, files in $out/sbin are not moved to + $out/bin. By default, they are. + + + + + stripAllList + + + + List of directories to search for libraries and executables from which + all symbols should be stripped. By default, it’s + empty. Stripping all symbols is risky, since it may remove not just + debug symbols but also ELF information necessary for normal execution. + + + + + stripAllFlags + + + + Flags passed to the strip command applied to the + files in the directories listed in stripAllList. + Defaults to (i.e. ). + + + + + stripDebugList + + + + List of directories to search for libraries and executables from which + only debugging-related symbols should be stripped. It defaults to + lib bin sbin. + + + + + stripDebugFlags + + + + Flags passed to the strip command applied to the + files in the directories listed in stripDebugList. + Defaults to (i.e. ). + + + + + dontPatchELF + + + + If set, the patchelf command is not used to remove + unnecessary RPATH entries. Only applies to Linux. + + + + + dontPatchShebangs + + + + If set, scripts starting with #! do not have their + interpreter paths rewritten to paths in the Nix store. + + + + + forceShare + + + + The list of directories that must be moved from + $out to $out/share. Defaults + to man doc info. + + + + + setupHook + + + + A package can export a setup + hook by setting this variable. The setup hook, if defined, is + copied to $out/nix-support/setup-hook. Environment + variables are then substituted in it using + substituteAll. + + + + + preFixup + + + + Hook executed at the start of the fixup phase. + + + + + postFixup + + + + Hook executed at the end of the fixup phase. + + + + + separateDebugInfo + + + + If set to true, the standard environment will enable + debug information in C/C++ builds. After installation, the debug + information will be separated from the executables and stored in the + output named debug. (This output is enabled + automatically; you don’t need to set the outputs + attribute explicitly.) To be precise, the debug information is stored in + debug/lib/debug/.build-id/XX/YYYY…, + where XXYYYY… is the build + ID of the binary — a SHA-1 hash of the contents of the + binary. Debuggers like GDB use the build ID to look up the separated + debug information. + + + For example, with GDB, you can add + +set debug-file-directory ~/.nix-profile/lib/debug + + to ~/.gdbinit. GDB will then be able to find debug + information installed via nix-env -i. + + + + +
+ +
+ The installCheck phase + + + The installCheck phase checks whether the package was installed correctly + by running its test suite against the installed directories. The default + installCheck calls make + installcheck. + + + + Variables controlling the installCheck phase + + doInstallCheck + + + + Controls whether the installCheck phase is executed. By default it is + skipped, but if doInstallCheck is set to true, the + installCheck phase is usually executed. Thus you should set +doInstallCheck = true; + in the derivation to enable install checks. The exception is cross + compilation. Cross compiled builds never run tests, no matter how + doInstallCheck is set, as the newly-built program + won't run on the platform used to build it. + + + + + preInstallCheck + + + + Hook executed at the start of the installCheck phase. + + + + + postInstallCheck + + + + Hook executed at the end of the installCheck phase. + + + + +
+ +
+ The distribution phase + + + The distribution phase is intended to produce a source distribution of the + package. The default distPhase first calls + make dist, then it copies the resulting source tarballs + to $out/tarballs/. This phase is only executed if the + attribute doDist is set. + + + + Variables controlling the distribution phase + + distTarget + + + + The make target that produces the distribution. Defaults to + dist. + + + + + distFlags / distFlagsArray + + + + Additional flags passed to make. + + + + + tarballs + + + + The names of the source distribution files to be copied to + $out/tarballs/. It can contain shell wildcards. The + default is *.tar.gz. + + + + + dontCopyDist + + + + If set, no files are copied to $out/tarballs/. + + + + + preDist + + + + Hook executed at the start of the distribution phase. + + + + + postDist + + + + Hook executed at the end of the distribution phase. + + + + +
+
+
+ Shell functions + + + The standard environment provides a number of useful functions. + + + + + makeWrapperexecutablewrapperfileargs + + + + Constructs a wrapper for a program with various possible arguments. For + example: # adds `FOOBAR=baz` to `$out/bin/foo`’s environment makeWrapper $out/bin/foo $wrapperfile --set FOOBAR baz @@ -1392,662 +1764,763 @@ makeWrapper $out/bin/foo $wrapperfile --set FOOBAR baz # (via string replacements or in `configurePhase`). makeWrapper $out/bin/foo $wrapperfile --prefix PATH : ${lib.makeBinPath [ hello git ]} - - There’s many more kinds of arguments, they are documented in - nixpkgs/pkgs/build-support/setup-hooks/make-wrapper.sh. - - wrapProgram is a convenience function you probably - want to use most of the time. - + There’s many more kinds of arguments, they are documented in + nixpkgs/pkgs/build-support/setup-hooks/make-wrapper.sh. + + + wrapProgram is a convenience function you probably + want to use most of the time. + - - - - - substitute - infile - outfile - subs - + + + substituteinfileoutfilesubs + - Performs string substitution on the contents of + + Performs string substitution on the contents of infile, writing the result to - outfile. The substitutions in + outfile. The substitutions in subs are of the following form: - - - - - s1 - s2 - Replace every occurrence of the string - s1 by - s2. - - - - - varName - Replace every occurrence of - @varName@ by - the contents of the environment variable - varName. This is useful for - generating files from templates, using - @...@ in the - template as placeholders. - - - - - varName - s - Replace every occurrence of - @varName@ by - the string s. - - - - - - - Example: - + + + s1s2 + + + + Replace every occurrence of the string s1 + by s2. + + + + + varName + + + + Replace every occurrence of + @varName@ by the + contents of the environment variable + varName. This is useful for generating + files from templates, using + @...@ in the template + as placeholders. + + + + + varNames + + + + Replace every occurrence of + @varName@ by the string + s. + + + + + + + Example: substitute ./foo.in ./foo.out \ --replace /usr/bin/bar $bar/bin/bar \ --replace "a string containing spaces" "some other text" \ --subst-var someVar - - - - substitute is implemented using the + + + substitute is implemented using the replace - command. Unlike with the sed command, you - don’t have to worry about escaping special characters. It - supports performing substitutions on binary files (such as - executables), though there you’ll probably want to make sure - that the replacement string is as long as the replaced - string. - + command. Unlike with the sed command, you don’t have + to worry about escaping special characters. It supports performing + substitutions on binary files (such as executables), though there + you’ll probably want to make sure that the replacement string is as + long as the replaced string. + - - - - - substituteInPlace - file - subs - Like substitute, but performs - the substitutions in place on the file - file. - - - - - substituteAll - infile - outfile - Replaces every occurrence of - @varName@, where - varName is any environment variable, in - infile, writing the result to - outfile. For instance, if - infile has the contents - + + + substituteInPlacefilesubs + + + + Like substitute, but performs the substitutions in + place on the file file. + + + + + substituteAllinfileoutfile + + + + Replaces every occurrence of + @varName@, where + varName is any environment variable, in + infile, writing the result to + outfile. For instance, if + infile has the contents #! @bash@/bin/sh PATH=@coreutils@/bin echo @foo@ - - and the environment contains - bash=/nix/store/bmwp0q28cf21...-bash-3.2-p39 - and - coreutils=/nix/store/68afga4khv0w...-coreutils-6.12, - but does not contain the variable foo, then the - output will be - + and the environment contains + bash=/nix/store/bmwp0q28cf21...-bash-3.2-p39 and + coreutils=/nix/store/68afga4khv0w...-coreutils-6.12, + but does not contain the variable foo, then the output + will be #! /nix/store/bmwp0q28cf21...-bash-3.2-p39/bin/sh PATH=/nix/store/68afga4khv0w...-coreutils-6.12/bin echo @foo@ - - That is, no substitution is performed for undefined variables. - - Environment variables that start with an uppercase letter or an - underscore are filtered out, - to prevent global variables (like HOME) or private - variables (like __ETC_PROFILE_DONE) from accidentally - getting substituted. - The variables also have to be valid bash “names”, as - defined in the bash manpage (alphanumeric or _, - must not start with a number). - - - - - - substituteAllInPlace - file - Like substituteAll, but performs - the substitutions in place on the file - file. - - - - - stripHash - path - Strips the directory and hash part of a store - path, outputting the name part to stdout. - For example: - + That is, no substitution is performed for undefined variables. + + + Environment variables that start with an uppercase letter or an + underscore are filtered out, to prevent global variables (like + HOME) or private variables (like + __ETC_PROFILE_DONE) from accidentally getting + substituted. The variables also have to be valid bash “names”, as + defined in the bash manpage (alphanumeric or _, must + not start with a number). + + + + + substituteAllInPlacefile + + + + Like substituteAll, but performs the substitutions + in place on the file file. + + + + + stripHashpath + + + + Strips the directory and hash part of a store path, outputting the name + part to stdout. For example: # prints coreutils-8.24 stripHash "/nix/store/9s9r019176g7cvn2nvcw41gsp862y6b4-coreutils-8.24" - - If you wish to store the result in another variable, then the - following idiom may be useful: - + If you wish to store the result in another variable, then the following + idiom may be useful: name="/nix/store/9s9r019176g7cvn2nvcw41gsp862y6b4-coreutils-8.24" someVar=$(stripHash $name) - - - - - - - wrapProgram - executable - makeWrapperArgs - Convenience function for makeWrapper - that automatically creates a sane wrapper file - - It takes all the same arguments as makeWrapper, - except for --argv0. - - It cannot be applied multiple times, since it will overwrite the wrapper - file. + + + + + wrapProgramexecutablemakeWrapperArgs + + + + Convenience function for makeWrapper that + automatically creates a sane wrapper file It takes all the same arguments + as makeWrapper, except for --argv0. + + + It cannot be applied multiple times, since it will overwrite the wrapper + file. + - - - - - -
- - -
Package setup hooks - - - Nix itself considers a build-time dependency merely something that should previously be built and accessible at build time—packages themselves are on their own to perform any additional setup. - In most cases, that is fine, and the downstream derivation can deal with it's own dependencies. - But for a few common tasks, that would result in almost every package doing the same sort of setup work---depending not on the package itself, but entirely on which dependencies were used. - - - In order to alleviate this burden, the setup hook>mechanism was written, where any package can include a shell script that [by convention rather than enforcement by Nix], any downstream reverse-dependency will source as part of its build process. - That allows the downstream dependency to merely specify its dependencies, and lets those dependencies effectively initialize themselves. - No boilerplate mirroring the list of dependencies is needed. - - - The Setup hook mechanism is a bit of a sledgehammer though: a powerful feature with a broad and indiscriminate area of effect. - The combination of its power and implicit use may be expedient, but isn't without costs. - Nix itself is unchanged, but the spirit of adding dependencies being effect-free is violated even if the letter isn't. - For example, if a derivation path is mentioned more than once, Nix itself doesn't care and simply makes sure the dependency derivation is already built just the same—depending is just needing something to exist, and needing is idempotent. - However, a dependency specified twice will have its setup hook run twice, and that could easily change the build environment (though a well-written setup hook will therefore strive to be idempotent so this is in fact not observable). - More broadly, setup hooks are anti-modular in that multiple dependencies, whether the same or different, should not interfere and yet their setup hooks may well do so. - - - The most typical use of the setup hook is actually to add other hooks which are then run (i.e. after all the setup hooks) on each dependency. - For example, the C compiler wrapper's setup hook feeds itself flags for each dependency that contains relevant libaries and headers. - This is done by defining a bash function, and appending its name to one of - envBuildBuildHooks`, - envBuildHostHooks`, - envBuildTargetHooks`, - envHostHostHooks`, - envHostTargetHooks`, or - envTargetTargetHooks`. - These 6 bash variables correspond to the 6 sorts of dependencies by platform (there's 12 total but we ignore the propagated/non-propagated axis). - - - Packages adding a hook should not hard code a specific hook, but rather choose a variable relative to how they are included. - Returning to the C compiler wrapper example, if it itself is an n dependency, then it only wants to accumulate flags from n + 1 dependencies, as only those ones match the compiler's target platform. - The hostOffset variable is defined with the current dependency's host offset targetOffset with its target offset, before it's setup hook is sourced. - Additionally, since most environment hooks don't care about the target platform, - That means the setup hook can append to the right bash array by doing something like - + + +
+
+ Package setup hooks + + + Nix itself considers a build-time dependency merely something that should + previously be built and accessible at build time—packages themselves are + on their own to perform any additional setup. In most cases, that is fine, + and the downstream derivation can deal with it's own dependencies. But for a + few common tasks, that would result in almost every package doing the same + sort of setup work---depending not on the package itself, but entirely on + which dependencies were used. + + + + In order to alleviate this burden, the setup + hook>mechanism was written, where any package can include a + shell script that [by convention rather than enforcement by Nix], any + downstream reverse-dependency will source as part of its build process. That + allows the downstream dependency to merely specify its dependencies, and + lets those dependencies effectively initialize themselves. No boilerplate + mirroring the list of dependencies is needed. + + + + The Setup hook mechanism is a bit of a sledgehammer though: a powerful + feature with a broad and indiscriminate area of effect. The combination of + its power and implicit use may be expedient, but isn't without costs. Nix + itself is unchanged, but the spirit of adding dependencies being effect-free + is violated even if the letter isn't. For example, if a derivation path is + mentioned more than once, Nix itself doesn't care and simply makes sure the + dependency derivation is already built just the same—depending is just + needing something to exist, and needing is idempotent. However, a dependency + specified twice will have its setup hook run twice, and that could easily + change the build environment (though a well-written setup hook will + therefore strive to be idempotent so this is in fact not observable). More + broadly, setup hooks are anti-modular in that multiple dependencies, whether + the same or different, should not interfere and yet their setup hooks may + well do so. + + + + The most typical use of the setup hook is actually to add other hooks which + are then run (i.e. after all the setup hooks) on each dependency. For + example, the C compiler wrapper's setup hook feeds itself flags for each + dependency that contains relevant libaries and headers. This is done by + defining a bash function, and appending its name to one of + envBuildBuildHooks`, envBuildHostHooks`, + envBuildTargetHooks`, envHostHostHooks`, + envHostTargetHooks`, or envTargetTargetHooks`. + These 6 bash variables correspond to the 6 sorts of dependencies by platform + (there's 12 total but we ignore the propagated/non-propagated axis). + + + + Packages adding a hook should not hard code a specific hook, but rather + choose a variable relative to how they are included. + Returning to the C compiler wrapper example, if it itself is an + n dependency, then it only wants to accumulate flags from + n + 1 dependencies, as only those ones match the + compiler's target platform. The hostOffset variable is + defined with the current dependency's host offset + targetOffset with its target offset, before it's setup hook + is sourced. Additionally, since most environment hooks don't care about the + target platform, That means the setup hook can append to the right bash + array by doing something like + addEnvHooks "$hostOffset" myBashFunction - - - The existence of setups hooks has long been documented and packages inside Nixpkgs are free to use these mechanism. - Other packages, however, should not rely on these mechanisms not changing between Nixpkgs versions. - Because of the existing issues with this system, there's little benefit from mandating it be stable for any period of time. - - - Here are some packages that provide a setup hook. - Since the mechanism is modular, this probably isn't an exhaustive list. - Then again, since the mechanism is only to be used as a last resort, it might be. - - - - Bintools Wrapper - + + + + The existence of setups hooks has long been documented + and packages inside Nixpkgs are free to use these mechanism. Other packages, + however, should not rely on these mechanisms not changing between Nixpkgs + versions. Because of the existing issues with this system, there's little + benefit from mandating it be stable for any period of time. + + + + Here are some packages that provide a setup hook. Since the mechanism is + modular, this probably isn't an exhaustive list. Then again, since the + mechanism is only to be used as a last resort, it might be. + + + Bintools Wrapper + - Bintools Wrapper wraps the binary utilities for a bunch of miscellaneous purposes. - These are GNU Binutils when targetting Linux, and a mix of cctools and GNU binutils for Darwin. - [The "Bintools" name is supposed to be a compromise between "Binutils" and "cctools" not denoting any specific implementation.] - Specifically, the underlying bintools package, and a C standard library (glibc or Darwin's libSystem, just for the dynamic loader) are all fed in, and dependency finding, hardening (see below), and purity checks for each are handled by Bintools Wrapper. - Packages typically depend on CC Wrapper, which in turn (at run time) depends on Bintools Wrapper. + Bintools Wrapper wraps the binary utilities for a bunch of miscellaneous + purposes. These are GNU Binutils when targetting Linux, and a mix of + cctools and GNU binutils for Darwin. [The "Bintools" name is supposed to + be a compromise between "Binutils" and "cctools" not denoting any + specific implementation.] Specifically, the underlying bintools package, + and a C standard library (glibc or Darwin's libSystem, just for the + dynamic loader) are all fed in, and dependency finding, hardening (see + below), and purity checks for each are handled by Bintools Wrapper. + Packages typically depend on CC Wrapper, which in turn (at run time) + depends on Bintools Wrapper. - Bintools Wrapper was only just recently split off from CC Wrapper, so the division of labor is still being worked out. - For example, it shouldn't care about about the C standard library, but just take a derivation with the dynamic loader (which happens to be the glibc on linux). - Dependency finding however is a task both wrappers will continue to need to share, and probably the most important to understand. - It is currently accomplished by collecting directories of host-platform dependencies (i.e. buildInputs and nativeBuildInputs) in environment variables. - Bintools Wrapper's setup hook causes any lib and lib64 subdirectories to be added to NIX_LDFLAGS. - Since CC Wrapper and Bintools Wrapper use the same strategy, most of the Bintools Wrapper code is sparsely commented and refers to CC Wrapper. - But CC Wrapper's code, by contrast, has quite lengthy comments. - Bintools Wrapper merely cites those, rather than repeating them, to avoid falling out of sync. + Bintools Wrapper was only just recently split off from CC Wrapper, so + the division of labor is still being worked out. For example, it + shouldn't care about about the C standard library, but just take a + derivation with the dynamic loader (which happens to be the glibc on + linux). Dependency finding however is a task both wrappers will continue + to need to share, and probably the most important to understand. It is + currently accomplished by collecting directories of host-platform + dependencies (i.e. buildInputs and + nativeBuildInputs) in environment variables. Bintools + Wrapper's setup hook causes any lib and + lib64 subdirectories to be added to + NIX_LDFLAGS. Since CC Wrapper and Bintools Wrapper use + the same strategy, most of the Bintools Wrapper code is sparsely + commented and refers to CC Wrapper. But CC Wrapper's code, by contrast, + has quite lengthy comments. Bintools Wrapper merely cites those, rather + than repeating them, to avoid falling out of sync. - A final task of the setup hook is defining a number of standard environment variables to tell build systems which executables full-fill which purpose. - They are defined to just be the base name of the tools, under the assumption that Bintools Wrapper's binaries will be on the path. - Firstly, this helps poorly-written packages, e.g. ones that look for just gcc when CC isn't defined yet clang is to be used. - Secondly, this helps packages not get confused when cross-compiling, in which case multiple Bintools Wrappers may simultaneously be in use. - - Each wrapper targets a single platform, so if binaries for multiple platforms are needed, the underlying binaries must be wrapped multiple times. - As this is a property of the wrapper itself, the multiple wrappings are needed whether or not the same underlying binaries can target multiple platforms. - - BUILD_- and TARGET_-prefixed versions of the normal environment variable are defined for the additional Bintools Wrappers, properly disambiguating them. + A final task of the setup hook is defining a number of standard + environment variables to tell build systems which executables full-fill + which purpose. They are defined to just be the base name of the tools, + under the assumption that Bintools Wrapper's binaries will be on the + path. Firstly, this helps poorly-written packages, e.g. ones that look + for just gcc when CC isn't defined yet + clang is to be used. Secondly, this helps packages + not get confused when cross-compiling, in which case multiple Bintools + Wrappers may simultaneously be in use. + + + Each wrapper targets a single platform, so if binaries for multiple + platforms are needed, the underlying binaries must be wrapped multiple + times. As this is a property of the wrapper itself, the multiple + wrappings are needed whether or not the same underlying binaries can + target multiple platforms. + + + BUILD_- and TARGET_-prefixed versions of + the normal environment variable are defined for the additional Bintools + Wrappers, properly disambiguating them. - A problem with this final task is that Bintools Wrapper is honest and defines LD as ld. - Most packages, however, firstly use the C compiler for linking, secondly use LD anyways, defining it as the C compiler, and thirdly, only so define LD when it is undefined as a fallback. - This triple-threat means Bintools Wrapper will break those packages, as LD is already defined as the actual linker which the package won't override yet doesn't want to use. - The workaround is to define, just for the problematic package, LD as the C compiler. - A good way to do this would be preConfigure = "LD=$CC". + A problem with this final task is that Bintools Wrapper is honest and + defines LD as ld. Most packages, + however, firstly use the C compiler for linking, secondly use + LD anyways, defining it as the C compiler, and thirdly, + only so define LD when it is undefined as a fallback. + This triple-threat means Bintools Wrapper will break those packages, as + LD is already defined as the actual linker which the package won't + override yet doesn't want to use. The workaround is to define, just for + the problematic package, LD as the C compiler. A good way + to do this would be preConfigure = "LD=$CC". - - - - - CC Wrapper - + + + + CC Wrapper + - CC Wrapper wraps a C toolchain for a bunch of miscellaneous purposes. - Specifically, a C compiler (GCC or Clang), wrapped binary tools, and a C standard library (glibc or Darwin's libSystem, just for the dynamic loader) are all fed in, and dependency finding, hardening (see below), and purity checks for each are handled by CC Wrapper. - Packages typically depend on CC Wrapper, which in turn (at run time) depends on Bintools Wrapper. + CC Wrapper wraps a C toolchain for a bunch of miscellaneous purposes. + Specifically, a C compiler (GCC or Clang), wrapped binary tools, and a C + standard library (glibc or Darwin's libSystem, just for the dynamic + loader) are all fed in, and dependency finding, hardening (see below), + and purity checks for each are handled by CC Wrapper. Packages typically + depend on CC Wrapper, which in turn (at run time) depends on Bintools + Wrapper. - Dependency finding is undoubtedly the main task of CC Wrapper. - This works just like Bintools Wrapper, except that any include subdirectory of any relevant dependency is added to NIX_CFLAGS_COMPILE. - The setup hook itself contains some lengthy comments describing the exact convoluted mechanism by which this is accomplished. + Dependency finding is undoubtedly the main task of CC Wrapper. This + works just like Bintools Wrapper, except that any + include subdirectory of any relevant dependency is + added to NIX_CFLAGS_COMPILE. The setup hook itself + contains some lengthy comments describing the exact convoluted mechanism + by which this is accomplished. - CC Wrapper also like Bintools Wrapper defines standard environment variables with the names of the tools it wraps, for the same reasons described above. - Importantly, while it includes a cc symlink to the c compiler for portability, the CC will be defined using the compiler's "real name" (i.e. gcc or clang). - This helps lousy build systems that inspect on the name of the compiler rather than run it. + CC Wrapper also like Bintools Wrapper defines standard environment + variables with the names of the tools it wraps, for the same reasons + described above. Importantly, while it includes a cc + symlink to the c compiler for portability, the CC will be + defined using the compiler's "real name" (i.e. gcc or + clang). This helps lousy build systems that inspect + on the name of the compiler rather than run it. - - - - - Perl - + + + + Perl + - Adds the lib/site_perl subdirectory of each build input to the PERL5LIB environment variable. - For instance, if buildInputs contains Perl, then the lib/site_perl subdirectory of each input is added to the PERL5LIB environment variable. + Adds the lib/site_perl subdirectory of each build + input to the PERL5LIB environment variable. For instance, + if buildInputs contains Perl, then the + lib/site_perl subdirectory of each input is added + to the PERL5LIB environment variable. - - - - - Python - Adds the - lib/${python.libPrefix}/site-packages subdirectory of - each build input to the PYTHONPATH environment - variable. - - - - pkg-config - Adds the lib/pkgconfig and - share/pkgconfig subdirectories of each - build input to the PKG_CONFIG_PATH environment - variable. - - - - Automake - Adds the share/aclocal - subdirectory of each build input to the ACLOCAL_PATH - environment variable. - - - - Autoconf - The autoreconfHook derivation adds - autoreconfPhase, which runs autoreconf, libtoolize and - automake, essentially preparing the configure script in autotools-based - builds. - - - - libxml2 - Adds every file named - catalog.xml found under the - xml/dtd and xml/xsl - subdirectories of each build input to the - XML_CATALOG_FILES environment - variable. - - - - teTeX / TeX Live - Adds the share/texmf-nix - subdirectory of each build input to the TEXINPUTS - environment variable. - - - - Qt 4 - Sets the QTDIR environment variable - to Qt’s path. - - - - gdk-pixbuf - Exports GDK_PIXBUF_MODULE_FILE - environment variable the the builder. Add librsvg package - to buildInputs to get svg support. - - - - GHC - Creates a temporary package database and registers - every Haskell build input in it (TODO: how?). - - - - GStreamer - Adds the - GStreamer plugins subdirectory of - each build input to the GST_PLUGIN_SYSTEM_PATH_1_0 or - GST_PLUGIN_SYSTEM_PATH environment variable. - - - - paxctl - Defines the paxmark helper for - setting per-executable PaX flags on Linux (where it is available by - default; on all other platforms, paxmark is a no-op). - For example, to disable secure memory protections on the executable - foo: - + + + + Python + + + Adds the lib/${python.libPrefix}/site-packages + subdirectory of each build input to the PYTHONPATH + environment variable. + + + + + pkg-config + + + Adds the lib/pkgconfig and + share/pkgconfig subdirectories of each build input + to the PKG_CONFIG_PATH environment variable. + + + + + Automake + + + Adds the share/aclocal subdirectory of each build + input to the ACLOCAL_PATH environment variable. + + + + + Autoconf + + + The autoreconfHook derivation adds + autoreconfPhase, which runs autoreconf, libtoolize + and automake, essentially preparing the configure script in + autotools-based builds. + + + + + libxml2 + + + Adds every file named catalog.xml found under the + xml/dtd and xml/xsl + subdirectories of each build input to the + XML_CATALOG_FILES environment variable. + + + + + teTeX / TeX Live + + + Adds the share/texmf-nix subdirectory of each build + input to the TEXINPUTS environment variable. + + + + + Qt 4 + + + Sets the QTDIR environment variable to Qt’s path. + + + + + gdk-pixbuf + + + Exports GDK_PIXBUF_MODULE_FILE environment variable the + the builder. Add librsvg package to buildInputs to + get svg support. + + + + + GHC + + + Creates a temporary package database and registers every Haskell build + input in it (TODO: how?). + + + + + GStreamer + + + Adds the GStreamer plugins subdirectory of each build input to the + GST_PLUGIN_SYSTEM_PATH_1_0 or + GST_PLUGIN_SYSTEM_PATH environment variable. + + + + + paxctl + + + Defines the paxmark helper for setting per-executable + PaX flags on Linux (where it is available by default; on all other + platforms, paxmark is a no-op). For example, to + disable secure memory protections on the executable + foo: + postFixup = '' paxmark m $out/bin/foo ''; - The m flag is the most common flag and is typically - required for applications that employ JIT compilation or otherwise need to - execute code generated at run-time. Disabling PaX protections should be - considered a last resort: if possible, problematic features should be - disabled or patched to work with PaX. - - - - autoPatchelfHook - This is a special setup hook which helps in packaging - proprietary software in that it automatically tries to find missing shared - library dependencies of ELF files. All packages within the - runtimeDependencies environment variable are unconditionally - added to executables, which is useful for programs that use - - dlopen - 3 - - to load libraries at runtime. - - - - - - -
- - -
Purity in Nixpkgs - -[measures taken to prevent dependencies on packages outside the -store, and what you can do to prevent them] - -GCC doesn't search in locations such as -/usr/include. In fact, attempts to add such -directories through the flag are filtered out. -Likewise, the linker (from GNU binutils) doesn't search in standard -locations such as /usr/lib. Programs built on -Linux are linked against a GNU C Library that likewise doesn't search -in the default system locations. - -
- -
Hardening in Nixpkgs - -There are flags available to harden packages at compile or link-time. -These can be toggled using the stdenv.mkDerivation parameters -hardeningDisable and hardeningEnable. - - - -Both parameters take a list of flags as strings. The special -"all" flag can be passed to hardeningDisable -to turn off all hardening. These flags can also be used as environment variables -for testing or development purposes. - - -The following flags are enabled by default and might require disabling with -hardeningDisable if the program to package is incompatible. - - - - - - format - Adds the compiler options. At present, - this warns about calls to printf and - scanf functions where the format string is - not a string literal and there are no format arguments, as in - printf(foo);. This may be a security hole - if the format string came from untrusted input and contains - %n. - - This needs to be turned off or fixed for errors similar to: - - + The m flag is the most common flag and is typically + required for applications that employ JIT compilation or otherwise need + to execute code generated at run-time. Disabling PaX protections should + be considered a last resort: if possible, problematic features should be + disabled or patched to work with PaX. + + + + + autoPatchelfHook + + + This is a special setup hook which helps in packaging proprietary + software in that it automatically tries to find missing shared library + dependencies of ELF files. All packages within the + runtimeDependencies environment variable are + unconditionally added to executables, which is useful for programs that + use + dlopen + 3 to load libraries at runtime. + + + + + +
+
+ Purity in Nixpkgs + + + [measures taken to prevent dependencies on packages outside the store, and + what you can do to prevent them] + + + + GCC doesn't search in locations such as /usr/include. + In fact, attempts to add such directories through the + flag are filtered out. Likewise, the linker (from GNU binutils) doesn't + search in standard locations such as /usr/lib. Programs + built on Linux are linked against a GNU C Library that likewise doesn't + search in the default system locations. + +
+
+ Hardening in Nixpkgs + + + There are flags available to harden packages at compile or link-time. These + can be toggled using the stdenv.mkDerivation parameters + hardeningDisable and hardeningEnable. + + + + Both parameters take a list of flags as strings. The special + "all" flag can be passed to + hardeningDisable to turn off all hardening. These flags + can also be used as environment variables for testing or development + purposes. + + + + The following flags are enabled by default and might require disabling with + hardeningDisable if the program to package is + incompatible. + + + + + format + + + + Adds the compiler options. At present, this warns + about calls to printf and scanf + functions where the format string is not a string literal and there are + no format arguments, as in printf(foo);. This may be a + security hole if the format string came from untrusted input and contains + %n. + + + This needs to be turned off or fixed for errors similar to: + + /tmp/nix-build-zynaddsubfx-2.5.2.drv-0/zynaddsubfx-2.5.2/src/UI/guimain.cpp:571:28: error: format not a string literal and no format arguments [-Werror=format-security] printf(help_message); ^ cc1plus: some warnings being treated as errors - - - - - stackprotector + + + + + stackprotector + - Adds the - compiler options. This adds safety checks against stack overwrites - rendering many potential code injection attacks into aborting situations. - In the best case this turns code injection vulnerabilities into denial - of service or into non-issues (depending on the application). - - This needs to be turned off or fixed for errors similar to: - - + + Adds the compiler options. This adds safety checks + against stack overwrites rendering many potential code injection attacks + into aborting situations. In the best case this turns code injection + vulnerabilities into denial of service or into non-issues (depending on + the application). + + + This needs to be turned off or fixed for errors similar to: + + bin/blib.a(bios_console.o): In function `bios_handle_cup': /tmp/nix-build-ipxe-20141124-5cbdc41.drv-0/ipxe-5cbdc41/src/arch/i386/firmware/pcbios/bios_console.c:86: undefined reference to `__stack_chk_fail' - - - - - fortify + + + + + fortify + - Adds the compiler - options. During code generation the compiler knows a great deal of - information about buffer sizes (where possible), and attempts to replace - insecure unlimited length buffer function calls with length-limited ones. - This is especially useful for old, crufty code. Additionally, format - strings in writable memory that contain '%n' are blocked. If an application - depends on such a format string, it will need to be worked around. - - - Additionally, some warnings are enabled which might trigger build - failures if compiler warnings are treated as errors in the package build. - In this case, set to - . - - This needs to be turned off or fixed for errors similar to: - - + + Adds the compiler options. + During code generation the compiler knows a great deal of information + about buffer sizes (where possible), and attempts to replace insecure + unlimited length buffer function calls with length-limited ones. This is + especially useful for old, crufty code. Additionally, format strings in + writable memory that contain '%n' are blocked. If an application depends + on such a format string, it will need to be worked around. + + + Additionally, some warnings are enabled which might trigger build + failures if compiler warnings are treated as errors in the package build. + In this case, set to + . + + + This needs to be turned off or fixed for errors similar to: + + malloc.c:404:15: error: return type is an incomplete type malloc.c:410:19: error: storage size of 'ms' isn't known - + strdup.h:22:1: error: expected identifier or '(' before '__extension__' - + strsep.c:65:23: error: register name not specified for 'delim' - + installwatch.c:3751:5: error: conflicting types for '__open_2' - + fcntl2.h:50:4: error: call to '__open_missing_mode' declared with attribute error: open with O_CREAT or O_TMPFILE in second argument needs 3 arguments - - - - pic + + + pic + - Adds the compiler options. This options adds - support for position independent code in shared libraries and thus making - ASLR possible. - Most notably, the Linux kernel, kernel modules and other code - not running in an operating system environment like boot loaders won't - build with PIC enabled. The compiler will is most cases complain that - PIC is not supported for a specific build. - - - This needs to be turned off or fixed for assembler errors similar to: - - + + Adds the compiler options. This options adds + support for position independent code in shared libraries and thus making + ASLR possible. + + + Most notably, the Linux kernel, kernel modules and other code not running + in an operating system environment like boot loaders won't build with PIC + enabled. The compiler will is most cases complain that PIC is not + supported for a specific build. + + + This needs to be turned off or fixed for assembler errors similar to: + + ccbLfRgg.s: Assembler messages: ccbLfRgg.s:33: Error: missing or invalid displacement expression `private_key_len@GOTOFF' - - - - strictoverflow + + + strictoverflow + - Signed integer overflow is undefined behaviour according to the C - standard. If it happens, it is an error in the program as it should check - for overflow before it can happen, not afterwards. GCC provides built-in - functions to perform arithmetic with overflow checking, which are correct - and faster than any custom implementation. As a workaround, the option - makes gcc behave as if signed - integer overflows were defined. - - - This flag should not trigger any build or runtime errors. + + Signed integer overflow is undefined behaviour according to the C + standard. If it happens, it is an error in the program as it should check + for overflow before it can happen, not afterwards. GCC provides built-in + functions to perform arithmetic with overflow checking, which are correct + and faster than any custom implementation. As a workaround, the option + makes gcc behave as if signed + integer overflows were defined. + + + This flag should not trigger any build or runtime errors. + - - - - relro + + + relro + - Adds the linker option. During program - load, several ELF memory sections need to be written to by the linker, - but can be turned read-only before turning over control to the program. - This prevents some GOT (and .dtors) overwrite attacks, but at least the - part of the GOT used by the dynamic linker (.got.plt) is still vulnerable. - - - This flag can break dynamic shared object loading. For instance, the - module systems of Xorg and OpenCV are incompatible with this flag. In almost - all cases the bindnow flag must also be disabled and - incompatible programs typically fail with similar errors at runtime. + + Adds the linker option. During program load, + several ELF memory sections need to be written to by the linker, but can + be turned read-only before turning over control to the program. This + prevents some GOT (and .dtors) overwrite attacks, but at least the part + of the GOT used by the dynamic linker (.got.plt) is still vulnerable. + + + This flag can break dynamic shared object loading. For instance, the + module systems of Xorg and OpenCV are incompatible with this flag. In + almost all cases the bindnow flag must also be + disabled and incompatible programs typically fail with similar errors at + runtime. + - - - - bindnow + + + bindnow + - Adds the linker option. During program - load, all dynamic symbols are resolved, allowing for the complete GOT to - be marked read-only (due to relro). This prevents GOT - overwrite attacks. For very large applications, this can incur some - performance loss during initial load while symbols are resolved, but this - shouldn't be an issue for daemons. - - - This flag can break dynamic shared object loading. For instance, the - module systems of Xorg and PHP are incompatible with this flag. Programs - incompatible with this flag often fail at runtime due to missing symbols, - like: - - + + Adds the linker option. During program load, + all dynamic symbols are resolved, allowing for the complete GOT to be + marked read-only (due to relro). This prevents GOT + overwrite attacks. For very large applications, this can incur some + performance loss during initial load while symbols are resolved, but this + shouldn't be an issue for daemons. + + + This flag can break dynamic shared object loading. For instance, the + module systems of Xorg and PHP are incompatible with this flag. Programs + incompatible with this flag often fail at runtime due to missing symbols, + like: + + intel_drv.so: undefined symbol: vgaHWFreeHWRec - - - - -The following flags are disabled by default and should be enabled -with hardeningEnable for packages that take untrusted -input like network services. - + + - + + The following flags are disabled by default and should be enabled with + hardeningEnable for packages that take untrusted input + like network services. + - - pie + + + pie + - Adds the compiler and - linker options. Position Independent Executables are needed to take - advantage of Address Space Layout Randomization, supported by modern - kernel versions. While ASLR can already be enforced for data areas in - the stack and heap (brk and mmap), the code areas must be compiled as - position-independent. Shared libraries already do this with the - pic flag, so they gain ASLR automatically, but binary - .text regions need to be build with pie to gain ASLR. - When this happens, ROP attacks are much harder since there are no static - locations to bounce off of during a memory corruption attack. - + + Adds the compiler and linker + options. Position Independent Executables are needed to take advantage of + Address Space Layout Randomization, supported by modern kernel versions. + While ASLR can already be enforced for data areas in the stack and heap + (brk and mmap), the code areas must be compiled as position-independent. + Shared libraries already do this with the pic flag, so + they gain ASLR automatically, but binary .text regions need to be build + with pie to gain ASLR. When this happens, ROP attacks + are much harder since there are no static locations to bounce off of + during a memory corruption attack. + - - - - -For more in-depth information on these hardening flags and hardening in -general, refer to the -Debian Wiki, -Ubuntu Wiki, -Gentoo Wiki, -and the -Arch Wiki. - - -
- + + + + + For more in-depth information on these hardening flags and hardening in + general, refer to the + Debian Wiki, + Ubuntu + Wiki, + Gentoo + Wiki, and the + + Arch Wiki. + +
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