+#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 */
+
+/*
+ * 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 */
+
+ 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);