1 files changed, 68 insertions, 9 deletions

diff --git a/exec_cmd.c b/exec_cmd.c
index cdd35f9195..f234066def 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -9,17 +9,78 @@ static const char *argv0_path;
 
 const char *system_path(const char *path)
 {
-	if (!is_absolute_path(path) && argv0_path) {
-		struct strbuf d = STRBUF_INIT;
-		strbuf_addf(&d, "%s/%s", argv0_path, path);
-		path = strbuf_detach(&d, NULL);
+#ifdef RUNTIME_PREFIX
+	static const char *prefix;
+#else
+	static const char *prefix = PREFIX;
+#endif
+	struct strbuf d = STRBUF_INIT;
+
+	if (is_absolute_path(path))
+		return path;
+
+#ifdef RUNTIME_PREFIX
+	assert(argv0_path);
+	assert(is_absolute_path(argv0_path));
+
+	if (!prefix) {
+		const char *strip[] = {
+			GIT_EXEC_PATH,
+			BINDIR,
+			0
+		};
+		const char **s;
+
+		for (s = strip; *s; s++) {
+			const char *sargv = argv0_path + strlen(argv0_path);
+			const char *ss = *s + strlen(*s);
+			while (argv0_path < sargv && *s < ss
+				&& (*sargv == *ss ||
+				    (is_dir_sep(*sargv) && is_dir_sep(*ss)))) {
+				sargv--;
+				ss--;
+			}
+			if (*s == ss) {
+				struct strbuf d = STRBUF_INIT;
+				/* We also skip the trailing directory separator. */
+				assert(sargv - argv0_path - 1 >= 0);
+				strbuf_add(&d, argv0_path, sargv - argv0_path - 1);
+				prefix = strbuf_detach(&d, NULL);
+				break;
+			}
+		}
 	}
+
+	if (!prefix) {
+		prefix = PREFIX;
+		fprintf(stderr, "RUNTIME_PREFIX requested, "
+				"but prefix computation failed.  "
+				"Using static fallback '%s'.\n", prefix);
+	}
+#endif
+
+	strbuf_addf(&d, "%s/%s", prefix, path);
+	path = strbuf_detach(&d, NULL);
 	return path;
 }
 
-void git_set_argv0_path(const char *path)
+const char *git_extract_argv0_path(const char *argv0)
 {
-	argv0_path = path;
+	const char *slash;
+
+	if (!argv0 || !*argv0)
+		return NULL;
+	slash = argv0 + strlen(argv0);
+
+	while (argv0 <= slash && !is_dir_sep(*slash))
+		slash--;
+
+	if (slash >= argv0) {
+		argv0_path = xstrndup(argv0, slash - argv0);
+		return slash + 1;
+	}
+
+	return argv0;
 }
 
 void git_set_argv_exec_path(const char *exec_path)
@@ -61,9 +122,7 @@ void setup_path(void)
 	const char *old_path = getenv("PATH");
 	struct strbuf new_path = STRBUF_INIT;
 
-	add_path(&new_path, argv_exec_path);
-	add_path(&new_path, getenv(EXEC_PATH_ENVIRONMENT));
-	add_path(&new_path, system_path(GIT_EXEC_PATH));
+	add_path(&new_path, git_exec_path());
 	add_path(&new_path, argv0_path);
 
 	if (old_path)