1 files changed, 231 insertions, 31 deletions

diff --git a/exec-cmd.c b/exec-cmd.c
index 8a8261746a..02d31ee897 100644
--- a/exec-cmd.c
+++ b/exec-cmd.c
@@ -2,25 +2,53 @@
 #include "exec-cmd.h"
 #include "quote.h"
 #include "argv-array.h"
-#define MAX_ARGS	32
 
-static const char *argv_exec_path;
+#if defined(RUNTIME_PREFIX)
+
+#if defined(HAVE_NS_GET_EXECUTABLE_PATH)
+#include <mach-o/dyld.h>
+#endif
+
+#if defined(HAVE_BSD_KERN_PROC_SYSCTL)
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#endif
+
+#endif /* RUNTIME_PREFIX */
+
+#define MAX_ARGS 32
+
+static const char *system_prefix(void);
 
 #ifdef RUNTIME_PREFIX
-static const char *argv0_path;
+
+/**
+ * When using a runtime prefix, Git dynamically resolves paths relative to its
+ * executable.
+ *
+ * The method for determining the path of the executable is highly
+ * platform-specific.
+ */
+
+/**
+ * Path to the current Git executable. Resolved on startup by
+ * 'git_resolve_executable_dir'.
+ */
+static const char *executable_dirname;
 
 static const char *system_prefix(void)
 {
 	static const char *prefix;
 
-	assert(argv0_path);
-	assert(is_absolute_path(argv0_path));
+	assert(executable_dirname);
+	assert(is_absolute_path(executable_dirname));
 
 	if (!prefix &&
-	    !(prefix = strip_path_suffix(argv0_path, GIT_EXEC_PATH)) &&
-	    !(prefix = strip_path_suffix(argv0_path, BINDIR)) &&
-	    !(prefix = strip_path_suffix(argv0_path, "git"))) {
-		prefix = PREFIX;
+	    !(prefix = strip_path_suffix(executable_dirname, GIT_EXEC_PATH)) &&
+	    !(prefix = strip_path_suffix(executable_dirname, BINDIR)) &&
+	    !(prefix = strip_path_suffix(executable_dirname, "git"))) {
+		prefix = FALLBACK_RUNTIME_PREFIX;
 		trace_printf("RUNTIME_PREFIX requested, "
 				"but prefix computation failed.  "
 				"Using static fallback '%s'.\n", prefix);
@@ -28,27 +56,201 @@ static const char *system_prefix(void)
 	return prefix;
 }
 
-void git_extract_argv0_path(const char *argv0)
+/*
+ * Resolves the executable path from argv[0], only if it is absolute.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int git_get_exec_path_from_argv0(struct strbuf *buf, const char *argv0)
 {
 	const char *slash;
 
 	if (!argv0 || !*argv0)
-		return;
+		return -1;
 
 	slash = find_last_dir_sep(argv0);
+	if (slash) {
+		trace_printf("trace: resolved executable path from argv0: %s\n",
+			     argv0);
+		strbuf_add_absolute_path(buf, argv0);
+		return 0;
+	}
+	return -1;
+}
+
+#ifdef PROCFS_EXECUTABLE_PATH
+/*
+ * Resolves the executable path by examining a procfs symlink.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int git_get_exec_path_procfs(struct strbuf *buf)
+{
+	if (strbuf_realpath(buf, PROCFS_EXECUTABLE_PATH, 0)) {
+		trace_printf(
+			"trace: resolved executable path from procfs: %s\n",
+			buf->buf);
+		return 0;
+	}
+	return -1;
+}
+#endif /* PROCFS_EXECUTABLE_PATH */
+
+#ifdef HAVE_BSD_KERN_PROC_SYSCTL
+/*
+ * Resolves the executable path using KERN_PROC_PATHNAME BSD sysctl.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int git_get_exec_path_bsd_sysctl(struct strbuf *buf)
+{
+	int mib[4];
+	char path[MAXPATHLEN];
+	size_t cb = sizeof(path);
+
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_PROC;
+	mib[2] = KERN_PROC_PATHNAME;
+	mib[3] = -1;
+	if (!sysctl(mib, 4, path, &cb, NULL, 0)) {
+		trace_printf(
+			"trace: resolved executable path from sysctl: %s\n",
+			path);
+		strbuf_addstr(buf, path);
+		return 0;
+	}
+	return -1;
+}
+#endif /* HAVE_BSD_KERN_PROC_SYSCTL */
+
+#ifdef HAVE_NS_GET_EXECUTABLE_PATH
+/*
+ * Resolves the executable path by querying Darwin application stack.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int git_get_exec_path_darwin(struct strbuf *buf)
+{
+	char path[PATH_MAX];
+	uint32_t size = sizeof(path);
+	if (!_NSGetExecutablePath(path, &size)) {
+		trace_printf(
+			"trace: resolved executable path from Darwin stack: %s\n",
+			path);
+		strbuf_addstr(buf, path);
+		return 0;
+	}
+	return -1;
+}
+#endif /* HAVE_NS_GET_EXECUTABLE_PATH */
+
+#ifdef HAVE_WPGMPTR
+/*
+ * Resolves the executable path by using the global variable _wpgmptr.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int git_get_exec_path_wpgmptr(struct strbuf *buf)
+{
+	int len = wcslen(_wpgmptr) * 3 + 1;
+	strbuf_grow(buf, len);
+	len = xwcstoutf(buf->buf, _wpgmptr, len);
+	if (len < 0)
+		return -1;
+	buf->len += len;
+	return 0;
+}
+#endif /* HAVE_WPGMPTR */
+
+/*
+ * Resolves the absolute path of the current executable.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int git_get_exec_path(struct strbuf *buf, const char *argv0)
+{
+	/*
+	 * Identifying the executable path is operating system specific.
+	 * Selectively employ all available methods in order of preference,
+	 * preferring highly-available authoritative methods over
+	 * selectively-available or non-authoritative methods.
+	 *
+	 * All cases fall back on resolving against argv[0] if there isn't a
+	 * better functional method. However, note that argv[0] can be
+	 * used-supplied on many operating systems, and is not authoritative
+	 * in those cases.
+	 *
+	 * Each of these functions returns 0 on success, so evaluation will stop
+	 * after the first successful method.
+	 */
+	if (
+#ifdef HAVE_BSD_KERN_PROC_SYSCTL
+		git_get_exec_path_bsd_sysctl(buf) &&
+#endif /* HAVE_BSD_KERN_PROC_SYSCTL */
+
+#ifdef HAVE_NS_GET_EXECUTABLE_PATH
+		git_get_exec_path_darwin(buf) &&
+#endif /* HAVE_NS_GET_EXECUTABLE_PATH */
+
+#ifdef PROCFS_EXECUTABLE_PATH
+		git_get_exec_path_procfs(buf) &&
+#endif /* PROCFS_EXECUTABLE_PATH */
+
+#ifdef HAVE_WPGMPTR
+		git_get_exec_path_wpgmptr(buf) &&
+#endif /* HAVE_WPGMPTR */
+
+		git_get_exec_path_from_argv0(buf, argv0)) {
+		return -1;
+	}
+
+	if (strbuf_normalize_path(buf)) {
+		trace_printf("trace: could not normalize path: %s\n", buf->buf);
+		return -1;
+	}
+
+	return 0;
+}
 
+void git_resolve_executable_dir(const char *argv0)
+{
+	struct strbuf buf = STRBUF_INIT;
+	char *resolved;
+	const char *slash;
+
+	if (git_get_exec_path(&buf, argv0)) {
+		trace_printf(
+			"trace: could not determine executable path from: %s\n",
+			argv0);
+		strbuf_release(&buf);
+		return;
+	}
+
+	resolved = strbuf_detach(&buf, NULL);
+	slash = find_last_dir_sep(resolved);
 	if (slash)
-		argv0_path = xstrndup(argv0, slash - argv0);
+		resolved[slash - resolved] = '\0';
+
+	executable_dirname = resolved;
+	trace_printf("trace: resolved executable dir: %s\n",
+		     executable_dirname);
 }
 
 #else
 
+/*
+ * When not using a runtime prefix, Git uses a hard-coded path.
+ */
 static const char *system_prefix(void)
 {
-	return PREFIX;
+	return FALLBACK_RUNTIME_PREFIX;
 }
 
-void git_extract_argv0_path(const char *argv0)
+/*
+ * This is called during initialization, but No work needs to be done here when
+ * runtime prefix is not being used.
+ */
+void git_resolve_executable_dir(const char *argv0)
 {
 }
 
@@ -65,32 +267,28 @@ char *system_path(const char *path)
 	return strbuf_detach(&d, NULL);
 }
 
-void git_set_argv_exec_path(const char *exec_path)
+static const char *exec_path_value;
+
+void git_set_exec_path(const char *exec_path)
 {
-	argv_exec_path = exec_path;
+	exec_path_value = exec_path;
 	/*
 	 * Propagate this setting to external programs.
 	 */
 	setenv(EXEC_PATH_ENVIRONMENT, exec_path, 1);
 }
 
-
-/* Returns the highest-priority, location to look for git programs. */
+/* Returns the highest-priority location to look for git programs. */
 const char *git_exec_path(void)
 {
-	static char *cached_exec_path;
-
-	if (argv_exec_path)
-		return argv_exec_path;
-
-	if (!cached_exec_path) {
+	if (!exec_path_value) {
 		const char *env = getenv(EXEC_PATH_ENVIRONMENT);
 		if (env && *env)
-			cached_exec_path = xstrdup(env);
+			exec_path_value = xstrdup(env);
 		else
-			cached_exec_path = system_path(GIT_EXEC_PATH);
+			exec_path_value = system_path(GIT_EXEC_PATH);
 	}
-	return cached_exec_path;
+	return exec_path_value;
 }
 
 static void add_path(struct strbuf *out, const char *path)
@@ -103,10 +301,12 @@ static void add_path(struct strbuf *out, const char *path)
 
 void setup_path(void)
 {
+	const char *exec_path = git_exec_path();
 	const char *old_path = getenv("PATH");
 	struct strbuf new_path = STRBUF_INIT;
 
-	add_path(&new_path, git_exec_path());
+	git_set_exec_path(exec_path);
+	add_path(&new_path, exec_path);
 
 	if (old_path)
 		strbuf_addstr(&new_path, old_path);
@@ -125,7 +325,8 @@ const char **prepare_git_cmd(struct argv_array *out, const char **argv)
 	return out->argv;
 }
 
-int execv_git_cmd(const char **argv) {
+int execv_git_cmd(const char **argv)
+{
 	struct argv_array nargv = ARGV_ARRAY_INIT;
 
 	prepare_git_cmd(&nargv, argv);
@@ -140,8 +341,7 @@ int execv_git_cmd(const char **argv) {
 	return -1;
 }
 
-
-int execl_git_cmd(const char *cmd,...)
+int execl_git_cmd(const char *cmd, ...)
 {
 	int argc;
 	const char *argv[MAX_ARGS + 1];