Move code interpreting path relative to exec-dir to new function system_path()

Expanding system paths relative to git_exec_path can be used for
creating an installation that can be moved to a different directory
without re-compiling.  We use this approach for template_dir and the
system wide gitconfig.  The Windows installer (msysgit) is an example
for such a setup.

This commit moves common code to a new function system_path().  System
paths that are to be interpreted relative to git_exec_path are passed to
system_path() and the return value is used instead of the original path.
system_path() prefixes a relative path with git_exec_path and leaves
absolute paths unmodified.  For example, we now write

    template_dir = system_path(DEFAULT_GIT_TEMPLATE_DIR);

[j6t: moved from path.c to exec_cmd.c]

Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-init-db.c

@@ -115,18 +115,8 @@ static void copy_templates(const char *template_dir)
 
 	if (!template_dir)
 		template_dir = getenv(TEMPLATE_DIR_ENVIRONMENT);
-	if (!template_dir) {
-		/*
-		 * if the hard-coded template is relative, it is
-		 * interpreted relative to the exec_dir
-		 */
-		template_dir = DEFAULT_GIT_TEMPLATE_DIR;
-		if (!is_absolute_path(template_dir)) {
-			struct strbuf d = STRBUF_INIT;
-			strbuf_addf(&d, "%s/%s", git_exec_path(), template_dir);
-			template_dir = strbuf_detach(&d, NULL);
-		}
-	}
+	if (!template_dir)
+		template_dir = system_path(DEFAULT_GIT_TEMPLATE_DIR);
 	strcpy(template_path, template_dir);
 	template_len = strlen(template_path);
 	if (template_path[template_len-1] != '/') {

config.c

@@ -581,15 +581,8 @@ int git_config_from_file(config_fn_t fn, const char *filename, void *data)
 const char *git_etc_gitconfig(void)
 {
 	static const char *system_wide;
-	if (!system_wide) {
-		system_wide = ETC_GITCONFIG;
-		if (!is_absolute_path(system_wide)) {
-			/* interpret path relative to exec-dir */
-			struct strbuf d = STRBUF_INIT;
-			strbuf_addf(&d, "%s/%s", git_exec_path(), system_wide);
-			system_wide = strbuf_detach(&d, NULL);
-		}
-	}
+	if (!system_wide)
+		system_wide = system_path(ETC_GITCONFIG);
 	return system_wide;
 }
 

exec_cmd.c

@@ -40,6 +40,16 @@ static const char *builtin_exec_path(void)
 #endif
 }
 
+const char *system_path(const char *path)
+{
+	if (!is_absolute_path(path)) {
+		struct strbuf d = STRBUF_INIT;
+		strbuf_addf(&d, "%s/%s", git_exec_path(), path);
+		path = strbuf_detach(&d, NULL);
+	}
+	return path;
+}
+
 void git_set_argv_exec_path(const char *exec_path)
 {
 	argv_exec_path = exec_path;

exec_cmd.h

@@ -6,6 +6,6 @@ extern const char* git_exec_path(void);
 extern void setup_path(const char *);
 extern int execv_git_cmd(const char **argv); /* NULL terminated */
 extern int execl_git_cmd(const char *cmd, ...);
-
+extern const char *system_path(const char *path);
 
 #endif /* GIT_EXEC_CMD_H */