1 files changed, 341 insertions, 0 deletions
diff --git a/nixpkgs/pkgs/development/tools/misc/saleae-logic/preload.c b/nixpkgs/pkgs/development/tools/misc/saleae-logic/preload.c
new file mode 100644
index 000000000000..b4451e4d99f7
--- /dev/null
+++ b/nixpkgs/pkgs/development/tools/misc/saleae-logic/preload.c
@@ -0,0 +1,341 @@
+/*
+ * LD_PRELOAD trick to make Saleae Logic work from a read-only installation
+ * directory.
+ *
+ * Saleae Logic tries to write to a few directories inside its installation
+ * directory. Because the Nix store is read-only, we have to redirect access to
+ * this file somewhere else. Here's the map:
+ *
+ *   $out/Settings/    => $HOME/.saleae-logic/Settings/
+ *   $out/Databases/   => $HOME/.saleae-logic/Databases/
+ *   $out/Errors/      => $HOME/.saleae-logic/Errors/
+ *   $out/Calibration/ => $HOME/.saleae-logic/Calibration/
+ *
+ * This also makes the software multi-user aware :-)
+ *
+ * NOTE: AFAIK (Bjørn Forsman), Logic version 1.2+ was supposed to have a
+ * command line parameter for redirecting these write operations, but
+ * apparently that feature got postponed.
+ *
+ * Usage:
+ *   gcc -shared -fPIC -DOUT="$out" preload.c -o preload.so -ldl
+ *   LD_PRELOAD=$PWD/preload.so ./result/Logic
+ *
+ * To see the paths that are modified at runtime, set the environment variable
+ * PRELOAD_DEBUG to 1 (or anything really; debugging is on as long as the
+ * variable exists).
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <dlfcn.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <errno.h>
+
+#ifndef OUT
+#error Missing OUT define - path to the installation directory.
+#endif
+
+/*
+ * TODO: How to properly wrap "open", which is declared as a variadic function
+ * in glibc? The man page lists these signatures:
+ *
+ *   int open(const char *pathname, int flags);
+ *   int open(const char *pathname, int flags, mode_t mode);
+ *
+ * But using either signature in this code cause a compile error, because
+ * glibc has declared the function as "int open(const char *, int, ...)".
+ * Same thing with "openat".
+ *
+ * For now we discard the variadic args. It seems to work.
+ *
+ * Relevant:
+ * http://stackoverflow.com/questions/28462523/how-to-wrap-ioctlint-d-unsigned-long-request-using-ld-preload
+ */
+typedef FILE *(*fopen_func_t)(const char *path, const char *mode);
+typedef FILE *(*fopen64_func_t)(const char *path, const char *mode);
+typedef int (*open_func_t)(const char *pathname, int flags, ...);
+typedef int (*open64_func_t)(const char *pathname, int flags, ...);
+typedef int (*openat_func_t)(int dirfd, const char *pathname, int flags, ...);
+typedef int (*openat64_func_t)(int dirfd, const char *pathname, int flags, ...);
+typedef int (*xstat_func_t)(int vers, const char *pathname, struct stat *buf);
+typedef int (*xstat64_func_t)(int vers, const char *pathname, struct stat64 *buf);
+typedef int (*access_func_t)(const char *pathname, int mode);
+typedef int (*faccessat_func_t)(int dirfd, const char *pathname, int mode, int flags);
+typedef int (*unlink_func_t)(const char *pathname);
+
+/*
+ * Redirect $out/{Settings,Databases,Errors,Calibration}/ => $HOME/.saleae-logic/.
+ * Path is truncated if bigger than PATH_MAX.
+ *
+ * @param pathname Original file path.
+ * @param buffer Pointer to a buffer of size PATH_MAX bytes that this function
+ * will write the new redirected path to (if needed).
+ *
+ * @return Pointer to the resulting path. It will either be equal to the
+ * pathname (no redirect) or buffer argument (was redirected).
+ */
+static const char *redirect(const char *pathname, char *buffer)
+{
+	const char *homepath;
+	const char *new_path;
+	static char have_warned;
+	const char *remainder;
+	static char have_initialized;
+	static size_t out_strlen;
+	static size_t settings_strlen;
+	static size_t databases_strlen;
+	static size_t errors_strlen;
+	static size_t calibration_strlen;
+	int ret;
+	int i;
+
+	homepath = getenv("HOME");
+	if (!homepath) {
+		homepath = "/";
+		if (!have_warned && getenv("PRELOAD_DEBUG")) {
+			fprintf(stderr, "preload_debug: WARNING: HOME is unset, using \"/\" (root) instead.\n");
+			have_warned = 1;
+		}
+	}
+
+	if (!have_initialized) {
+		/*
+		 * The directories that Saleae Logic expects to find.
+		 * The first element is intentionally empty (create base dir).
+		 */
+		char *dirs[] = {"", "/Settings", "/Databases", "/Errors", "/Calibration"};
+		char old_settings_path[PATH_MAX];
+		access_func_t orig_access;
+
+		out_strlen = strlen(OUT);
+		settings_strlen = out_strlen + strlen("/Settings");
+		databases_strlen = out_strlen + strlen("/Databases");
+		errors_strlen = out_strlen + strlen("/Errors");
+		calibration_strlen = out_strlen + strlen("/Calibration");
+		for (i = 0; i < sizeof dirs / sizeof dirs[0]; i++) {
+			snprintf(buffer, PATH_MAX, "%s/.saleae-logic%s", homepath, dirs[i]);
+			buffer[PATH_MAX-1] = '\0';
+			ret = mkdir(buffer, 0755);
+			if (0 != ret && errno != EEXIST) {
+				fprintf(stderr, "ERROR: Failed to create directory \"%s\": %s\n",
+						buffer, strerror(errno));
+				return NULL;
+			}
+		}
+
+		/*
+		 * Automatic migration of the settings file:
+		 * ~/.saleae-logic-settings.xml => ~/.saleae-logic/Settings/settings.xml
+		 */
+		snprintf(old_settings_path, PATH_MAX, "%s/.saleae-logic-settings.xml", homepath);
+		old_settings_path[PATH_MAX-1] = '\0';
+		orig_access = (access_func_t)dlsym(RTLD_NEXT, "access");
+		if (orig_access(old_settings_path, F_OK) == 0) {
+			snprintf(buffer, PATH_MAX, "%s/.saleae-logic/Settings/settings.xml", homepath);
+			buffer[PATH_MAX-1] = '\0';
+			ret = rename(old_settings_path, buffer);
+			if (ret != 0) {
+				fprintf(stderr, "WARN: Failed to move %s to %s",
+						old_settings_path, buffer);
+			}
+		}
+
+		have_initialized = 1;
+	}
+
+	new_path = pathname;
+	remainder = pathname + out_strlen;
+
+	if ((strncmp(OUT "/Settings", pathname, settings_strlen) == 0) ||
+	    (strncmp(OUT "/Databases", pathname, databases_strlen) == 0) ||
+	    (strncmp(OUT "/Errors", pathname, errors_strlen) == 0) ||
+	    (strncmp(OUT "/Calibration", pathname, calibration_strlen) == 0)) {
+		snprintf(buffer, PATH_MAX, "%s/.saleae-logic%s", homepath, remainder);
+		buffer[PATH_MAX-1] = '\0';
+		new_path = buffer;
+	}
+
+	return new_path;
+}
+
+FILE *fopen(const char *pathname, const char *mode)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	fopen_func_t orig_fopen;
+
+	orig_fopen = (fopen_func_t)dlsym(RTLD_NEXT, "fopen");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: fopen(\"%s\", \"%s\") => \"%s\"\n", pathname, mode, path);
+	}
+
+	return orig_fopen(path, mode);
+}
+
+FILE *fopen64(const char *pathname, const char *mode)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	fopen64_func_t orig_fopen64;
+
+	orig_fopen64 = (fopen64_func_t)dlsym(RTLD_NEXT, "fopen64");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: fopen64(\"%s\", \"%s\") => \"%s\"\n", pathname, mode, path);
+	}
+
+	return orig_fopen64(path, mode);
+}
+
+int open(const char *pathname, int flags, ...)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	open_func_t orig_open;
+
+	orig_open = (open_func_t)dlsym(RTLD_NEXT, "open");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: open(\"%s\", ...) => \"%s\"\n", pathname, path);
+	}
+
+	return orig_open(path, flags);
+}
+
+int open64(const char *pathname, int flags, ...)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	open64_func_t orig_open64;
+
+	orig_open64 = (open64_func_t)dlsym(RTLD_NEXT, "open64");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: open64(\"%s\", ...) => \"%s\"\n", pathname, path);
+	}
+
+	return orig_open64(path, flags);
+}
+
+int openat(int dirfd, const char *pathname, int flags, ...)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	openat_func_t orig_openat;
+
+	orig_openat = (openat_func_t)dlsym(RTLD_NEXT, "openat");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: openat(%d, \"%s\", %#x) => \"%s\"\n", dirfd, pathname, flags, path);
+	}
+
+	return orig_openat(dirfd, path, flags);
+}
+
+int openat64(int dirfd, const char *pathname, int flags, ...)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	openat64_func_t orig_openat64;
+
+	orig_openat64 = (openat64_func_t)dlsym(RTLD_NEXT, "openat64");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: openat64(%d, \"%s\", %#x) => \"%s\"\n", dirfd, pathname, flags, path);
+	}
+
+	return orig_openat64(dirfd, path, flags);
+}
+
+/*
+ * Notes about "stat".
+ *
+ * The stat function is special, at least in glibc, in that it cannot be
+ * directly overridden by LD_PRELOAD, due to it being inline wrapper around
+ * __xstat. The __xstat functions take one extra parameter, a version number,
+ * to indicate what "struct stat" should look like. This trick allows changing
+ * the contents of mode_t without changing the shared library major number. See
+ * sys/stat.h header for more info.
+ */
+int __xstat(int vers, const char *pathname, struct stat *buf)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	xstat_func_t orig_xstat;
+
+	orig_xstat = (xstat_func_t)dlsym(RTLD_NEXT, "__xstat");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: (__x)stat(\"%s\", ...) => \"%s\"\n", pathname, path);
+	}
+
+	return orig_xstat(vers, path, buf);
+}
+
+int __xstat64(int vers, const char *pathname, struct stat64 *buf)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	xstat64_func_t orig_xstat64;
+
+	orig_xstat64 = (xstat64_func_t)dlsym(RTLD_NEXT, "__xstat64");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: (__x)stat64(\"%s\", ...) => \"%s\"\n", pathname, path);
+	}
+
+	return orig_xstat64(vers, path, buf);
+}
+
+int access(const char *pathname, int mode)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	access_func_t orig_access;
+
+	orig_access = (access_func_t)dlsym(RTLD_NEXT, "access");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: access(\"%s\", ...) => \"%s\"\n", pathname, path);
+	}
+
+	return orig_access(path, mode);
+}
+
+int faccessat(int dirfd, const char *pathname, int mode, int flags)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	faccessat_func_t orig_faccessat;
+
+	orig_faccessat = (faccessat_func_t)dlsym(RTLD_NEXT, "faccessat");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: faccessat(\"%s\", ...) => \"%s\"\n", pathname, path);
+	}
+
+	return orig_faccessat(dirfd, path, mode, flags);
+}
+
+int unlink(const char *pathname)
+{
+	const char *path;
+	char buffer[PATH_MAX];
+	unlink_func_t orig_unlink;
+
+	orig_unlink = (unlink_func_t)dlsym(RTLD_NEXT, "unlink");
+	path = redirect(pathname, buffer);
+	if (path != pathname && getenv("PRELOAD_DEBUG")) {
+		fprintf(stderr, "preload_debug: unlink(\"%s\") => \"%s\"\n", pathname, path);
+	}
+
+	return orig_unlink(path);
+}