diff options
Diffstat (limited to 'lib/modules.nix')
| -rw-r--r-- | lib/modules.nix | 576 |
1 files changed, 221 insertions, 355 deletions
diff --git a/lib/modules.nix b/lib/modules.nix index f914947e7849..f5a82d7d8e9d 100644 --- a/lib/modules.nix +++ b/lib/modules.nix @@ -1,379 +1,245 @@ -# NixOS module handling. - -let lib = import ./default.nix; in - -with { inherit (builtins) head; }; -with import ./trivial.nix; -with import ./lists.nix; -with import ./misc.nix; -with import ./attrsets.nix; -with import ./options.nix; -with import ./properties.nix; +with import ./.. {}; +with lib; rec { - # Unfortunately this can also be a string. - isPath = x: !( - builtins.isFunction x - || builtins.isAttrs x - || builtins.isInt x - || builtins.isBool x - || builtins.isList x - ); - - - importIfPath = path: - if isPath path then - import path - else - path; - - - applyIfFunction = f: arg: - if builtins.isFunction f then - f arg - else - f; - - - isModule = m: - (m ? config && isAttrs m.config && ! isOption m.config) - || (m ? options && isAttrs m.options && ! isOption m.options); - - - # Convert module to a set which has imports / options and config - # attributes. - unifyModuleSyntax = m: + /* Evaluate a set of modules. The result is a set of two + attributes: ‘options’: the nested set of all option declarations, + and ‘config’: the nested set of all option values. */ + evalModules = modules: args: let - delayedModule = delayProperties m; - - getImports = - toList (rmProperties (delayedModule.require or [])); - getImportedPaths = filter isPath getImports; - getImportedSets = filter (x: !isPath x) getImports; - - getConfig = - removeAttrs delayedModule ["require" "key" "imports"]; - - in - if isModule m then - { key = "<unknown location>"; } // m - else - { key = "<unknown location>"; - imports = (m.imports or []) ++ getImportedPaths; - config = getConfig; - } // ( - if getImportedSets != [] then - assert length getImportedSets == 1; - { options = head getImportedSets; } - else - {} - ); - - - unifyOptionModule = {key ? "<unknown location>"}: name: index: m: (args: + args' = args // result; + closed = closeModules modules args'; + # Note: the list of modules is reversed to maintain backward + # compatibility with the old module system. Not sure if this is + # the most sensible policy. + options = mergeModules (reverseList closed); + config = yieldConfig options; + yieldConfig = mapAttrs (n: v: if isOption v then v.value else yieldConfig v); + result = { inherit options config; }; + in result; + + /* Close a set of modules under the ‘imports’ relation. */ + closeModules = modules: args: let - module = lib.applyIfFunction m args; - key_ = rec { - file = key; - option = name; - number = index; - outPath = key; + coerceToModule = n: x: + if isAttrs x || builtins.isFunction x then + unifyModuleSyntax "anon-${toString n}" (applyIfFunction x args) + else + unifyModuleSyntax (toString x) (applyIfFunction (import x) args); + toClosureList = imap (path: coerceToModule path); + in + builtins.genericClosure { + startSet = toClosureList modules; + operator = m: toClosureList m.imports; }; - in if lib.isModule module then - { key = key_; } // module - else - { key = key_; options = module; } - ); + /* Massage a module into canonical form, that is, a set consisting + of ‘options’, ‘config’ and ‘imports’ attributes. */ + unifyModuleSyntax = key: m: + if m ? config || m ? options || m ? imports then + let badAttrs = removeAttrs m ["imports" "options" "config"]; in + if badAttrs != {} then + throw "Module `${key}' has an unsupported attribute `${head (attrNames badAttrs)}'. ${builtins.toXML m} " + else + { inherit key; + imports = m.imports or []; + options = m.options or {}; + config = m.config or {}; + } + else + { inherit key; + imports = m.require or []; + options = {}; + config = m; + }; - moduleClosure = initModules: args: + applyIfFunction = f: arg: if builtins.isFunction f then f arg else f; + + /* Merge a list of modules. This will recurse over the option + declarations in all modules, combining them into a single set. + At the same time, for each option declaration, it will merge the + corresponding option definitions in all machines, returning them + in the ‘value’ attribute of each option. */ + mergeModules = modules: + mergeModules' [] (map (m: m.options) modules) (concatMap (m: pushDownProperties m.config) modules); + + mergeModules' = loc: options: configs: + zipAttrsWith (name: vals: + let loc' = loc ++ [name]; in + if all isOption vals then + let opt = fixupOptionType loc' (mergeOptionDecls loc' vals); + in evalOptionValue loc' opt (catAttrs name configs) + else if any isOption vals then + throw "There are options with the prefix `${showOption loc'}', which is itself an option." + else + mergeModules' loc' vals (concatMap pushDownProperties (catAttrs name configs)) + ) options; + + /* Merge multiple option declarations into a single declaration. In + general, there should be only one declaration of each option. + The exception is the ‘options’ attribute, which specifies + sub-options. These can be specified multiple times to allow one + module to add sub-options to an option declared somewhere else + (e.g. multiple modules define sub-options for ‘fileSystems’). */ + mergeOptionDecls = loc: opts: + fold (opt1: opt2: + if opt1 ? default && opt2 ? default || + opt1 ? example && opt2 ? example || + opt1 ? description && opt2 ? description || + opt1 ? merge && opt2 ? merge || + opt1 ? apply && opt2 ? apply || + opt1 ? type && opt2 ? type + then + throw "Conflicting declarations of the option `${showOption loc}'." + else + opt1 // opt2 + // optionalAttrs (opt1 ? options && opt2 ? options) + { options = [ opt1.options opt2.options ]; } + ) {} opts; + + /* Merge all the definitions of an option to produce the final + config value. */ + evalOptionValue = loc: opt: defs: let - moduleImport = origin: index: m: - let m' = applyIfFunction (importIfPath m) args; - in (unifyModuleSyntax m') // { - # used by generic closure to avoid duplicated imports. - key = - if isPath m then m - else m'.key or (newModuleName origin index); - }; - - getImports = m: m.imports or []; - - newModuleName = origin: index: - "${origin.key}:<import-${toString index}>"; - - topLevel = { - key = "<top-level>"; + # Process mkMerge and mkIf properties. + defs' = concatMap dischargeProperties defs; + # Process mkOverride properties, adding in the default + # value specified in the option declaration (if any). + defsFinal = filterOverrides (optional (opt ? default) (mkOptionDefault opt.default) ++ defs'); + # Type-check the remaining definitions, and merge them + # if possible. + merged = + if defsFinal == [] then + throw "The option `${showOption loc}' is used but not defined." + else + if all opt.type.check defsFinal then + opt.type.merge defsFinal + #throw "The option `${showOption loc}' has multiple values (with no way to merge them)." + else + throw "A value of the option `${showOption loc}' has a bad type."; + # Finally, apply the ‘apply’ function to the merged + # value. This allows options to yield a value computed + # from the definitions. + value = (opt.apply or id) merged; + in opt // + { inherit value; + definitions = defsFinal; + isDefined = defsFinal != []; }; - in - (lazyGenericClosure { - startSet = imap (moduleImport topLevel) initModules; - operator = m: imap (moduleImport m) (getImports m); - }); + /* Given a config set, expand mkMerge properties, and push down the + mkIf properties into the children. The result is a list of + config sets that do not have properties at top-level. For + example, + mkMerge [ { boot = set1; } (mkIf cond { boot = set2; services = set3; }) ] - moduleApply = funs: module: - lib.mapAttrs (name: value: - if builtins.hasAttr name funs then - let fun = lib.getAttr name funs; in - fun value - else - value - ) module; + is transformed into + [ { boot = set1; } { boot = mkIf cond set2; services mkIf cond set3; } ]. - # Handle mkMerge function left behind after a delay property. - moduleFlattenMerge = module: - if module ? config && - isProperty module.config && - isMerge module.config.property - then - (map (cfg: { key = module.key; config = cfg; }) module.config.content) - ++ [ (module // { config = {}; }) ] + This transform is the critical step that allows mkIf conditions + to refer to the full configuration without creating an infinite + recursion. + */ + pushDownProperties = cfg: + if cfg._type or "" == "merge" then + concatMap pushDownProperties cfg.contents + else if cfg._type or "" == "if" then + map (mapAttrs (n: v: mkIf cfg.condition v)) (pushDownProperties cfg.content) else - [ module ]; - - - # Handle mkMerge attributes which are left behind by previous delay - # properties and convert them into a list of modules. Delay properties - # inside the config attribute of a module and create a second module if a - # mkMerge attribute was left behind. - # - # Module -> [ Module ] - delayModule = module: - map (moduleApply { config = delayProperties; }) (moduleFlattenMerge module); - - - evalDefinitions = opt: values: - if opt.type.delayOnGlobalEval or false then - map (delayPropertiesWithIter opt.type.iter opt.name) - (evalLocalProperties values) + # FIXME: handle mkOverride? + [ cfg ]; + + /* Given a config value, expand mkMerge properties, and discharge + any mkIf conditions. That is, this is the place where mkIf + conditions are actually evaluated. The result is a list of + config values. For example, ‘mkIf false x’ yields ‘[]’, + ‘mkIf true x’ yields ‘[x]’, and + + mkMerge [ 1 (mkIf true 2) (mkIf true (mkIf false 3)) ] + + yields ‘[ 1 2 ]’. + */ + dischargeProperties = def: + if def._type or "" == "merge" then + concatMap dischargeProperties def.contents + else if def._type or "" == "if" then + if def.condition then + dischargeProperties def.content + else + [ ] else - evalProperties values; - - - selectModule = name: m: - { inherit (m) key; - } // ( - if m ? options && builtins.hasAttr name m.options then - { options = lib.getAttr name m.options; } - else {} - ) // ( - if m ? config && builtins.hasAttr name m.config then - { config = lib.getAttr name m.config; } - else {} - ); - - filterModules = name: modules: - filter (m: m ? config || m ? options) ( - map (selectModule name) modules - ); + [ def ]; + /* Given a list of config value, process the mkOverride properties, + that is, return the values that have the highest (that + is,. numerically lowest) priority, and strip the mkOverride + properties. For example, - modulesNames = modules: - lib.concatMap (m: [] - ++ optionals (m ? options) (lib.attrNames m.options) - ++ optionals (m ? config) (lib.attrNames m.config) - ) modules; + [ (mkOverride 10 "a") (mkOverride 20 "b") "z" (mkOverride 10 "d") ] - - moduleZip = funs: modules: - lib.mapAttrs (name: fun: - fun (catAttrs name modules) - ) funs; - - - moduleMerge = path: modules_: + yields ‘[ "a" "d" ]’. Note that "z" has the default priority 100. + */ + filterOverrides = defs: let - addName = name: - if path == "" then name else path + "." + name; - - modules = concatLists (map delayModule modules_); - - modulesOf = name: filterModules name modules; - declarationsOf = name: filter (m: m ? options) (modulesOf name); - definitionsOf = name: filter (m: m ? config ) (modulesOf name); - - recurseInto = name: - moduleMerge (addName name) (modulesOf name); - - recurseForOption = name: modules: args: - moduleMerge name ( - moduleClosure modules args - ); - - errorSource = modules: - "The error may come from the following files:\n" + ( - lib.concatStringsSep "\n" ( - map (m: - if m ? key then toString m.key else "<unknown location>" - ) modules - ) - ); - - eol = "\n"; - - allNames = modulesNames modules; - - getResults = m: - let fetchResult = s: mapAttrs (n: v: v.result) s; in { - options = fetchResult m.options; - config = fetchResult m.config; - }; - - endRecursion = { options = {}; config = {}; }; - - in if modules == [] then endRecursion else - getResults (fix (crossResults: moduleZip { - options = lib.zipWithNames allNames (name: values: rec { - config = lib.getAttr name crossResults.config; - - declarations = declarationsOf name; - declarationSources = - map (m: { - source = m.key; - }) declarations; - - hasOptions = values != []; - isOption = any lib.isOption values; - - decls = # add location to sub-module options. - map (m: - mapSubOptions - (unifyOptionModule {inherit (m) key;} name) - m.options - ) declarations; - - decl = - lib.addErrorContext "${eol - }while enhancing option `${addName name}':${eol - }${errorSource declarations}${eol - }" ( - addOptionMakeUp - { name = addName name; recurseInto = recurseForOption; } - (mergeOptionDecls decls) - ); - - value = decl // (with config; { - inherit (config) isNotDefined; - isDefined = ! isNotDefined; - declarations = declarationSources; - definitions = definitionSources; - config = strictResult; - }); - - recurse = (recurseInto name).options; - - result = - if isOption then value - else if !hasOptions then {} - else if all isAttrs values then recurse - else - throw "${eol - }Unexpected type where option declarations are expected.${eol - }${errorSource declarations}${eol - }"; - - }); - - config = lib.zipWithNames allNames (name: values_: rec { - option = lib.getAttr name crossResults.options; - - definitions = definitionsOf name; - definitionSources = - map (m: { - source = m.key; - value = m.config; - }) definitions; - - values = values_ ++ - optionals (option.isOption && option.decl ? extraConfigs) - option.decl.extraConfigs; - - defs = evalDefinitions option.decl values; - - isNotDefined = defs == []; - - value = - lib.addErrorContext "${eol - }while evaluating the option `${addName name}':${eol - }${errorSource (modulesOf name)}${eol - }" ( - let opt = option.decl; in - opt.apply ( - if isNotDefined then - opt.default or (throw "Option `${addName name}' not defined and does not have a default value.") - else opt.merge defs - ) - ); - - strictResult = builtins.tryEval (builtins.toXML value); - - recurse = (recurseInto name).config; - - configIsAnOption = v: isOption (rmProperties v); - errConfigIsAnOption = - let badModules = filter (m: configIsAnOption m.config) definitions; in - "${eol - }Option ${addName name} is defined in the configuration section.${eol - }${errorSource badModules}${eol - }"; - - errDefinedWithoutDeclaration = - let badModules = definitions; in - "${eol - }Option '${addName name}' defined without option declaration.${eol - }${errorSource badModules}${eol - }"; - - result = - if option.isOption then value - else if !option.hasOptions then throw errDefinedWithoutDeclaration - else if any configIsAnOption values then throw errConfigIsAnOption - else if all isAttrs values then recurse - # plain value during the traversal - else throw errDefinedWithoutDeclaration; - - }); - } modules)); - - - fixMergeModules = initModules: {...}@args: - lib.fix (result: - # This trick avoids an infinite loop because names of attribute - # are know and it is not required to evaluate the result of - # moduleMerge to know which attributes are present as arguments. - let module = { inherit (result) options config; }; in - moduleMerge "" ( - moduleClosure initModules (module // args) - ) - ); - - - # Visit all definitions to raise errors related to undeclared options. - checkModule = path: {config, options, ...}@m: + defaultPrio = 100; + getPrio = def: if def._type or "" == "override" then def.priority else defaultPrio; + min = x: y: if x < y then x else y; + highestPrio = fold (def: prio: min (getPrio def) prio) 9999 defs; + strip = def: if def._type or "" == "override" then def.content else def; + in concatMap (def: if getPrio def == highestPrio then [(strip def)] else []) defs; + + /* Hack for backward compatibility: convert options of type + optionSet to configOf. FIXME: remove eventually. */ + fixupOptionType = loc: opt: let - eol = "\n"; - addName = name: - if path == "" then name else path + "." + name; - in - if lib.isOption options then - if options ? options then - options.type.fold - (cfg: res: res && checkModule (options.type.docPath path) cfg._args) - true config - else - true - else if isAttrs options && lib.attrNames m.options != [] then - all (name: - lib.addErrorContext "${eol - }while checking the attribute `${addName name}':${eol - }" (checkModule (addName name) (selectModule name m)) - ) (lib.attrNames m.config) - else - builtins.trace "try to evaluate config ${lib.showVal config}." - false; + options' = opt.options or + (throw "Option `${showOption loc'}' has type optionSet but has no option attribute."); + coerce = x: + if builtins.isFunction x then x + else { config, ... }: { options = x; }; + options = map coerce (flatten options'); + f = tp: + if tp.name == "option set" then types.submodule options + else if tp.name == "attribute set of option sets" then types.attrsOf (types.submodule options) + else if tp.name == "list or attribute set of option sets" then types.loaOf (types.submodule options) + else if tp.name == "list of option sets" then types.listOf (types.submodule options) + else if tp.name == "null or option set" then types.nullOr (types.submodule options) + else tp; + in opt // { type = f (opt.type or types.unspecified); }; + + + /* Properties. */ + + mkIf = condition: content: + { _type = "if"; + inherit condition content; + }; + + mkAssert = assertion: message: content: + mkIf + (if assertion then true else throw "\nFailed assertion: ${message}") + content; + + mkMerge = contents: + { _type = "merge"; + inherit contents; + }; + + mkOverride = priority: content: + { _type = "override"; + inherit priority content; + }; + + mkOptionDefault = mkOverride 1001; + mkDefault = mkOverride 1000; + mkForce = mkOverride 50; + + mkFixStrictness = id; # obsolete, no-op + + # FIXME: Add mkOrder back in. It's not currently used anywhere in + # NixOS, but it should be useful. } |