git-daemon --base-path

Tommi Virtanen expressed a wish on #git to be able to use short and elegant
git URLs by making git-daemon 'root' in a given directory. This patch
implements this, causing git-daemon to interpret all paths relative to
the given base path if any is given.
Signed-off-by: NPetr Baudis <pasky@suse.cz>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Documentation/git-daemon.txt

@@ -9,7 +9,8 @@ SYNOPSIS
 --------
 [verse]
 'git-daemon' [--verbose] [--syslog] [--inetd | --port=n] [--export-all]
-           [--timeout=n] [--init-timeout=n] [--strict-paths] [directory...]
+             [--timeout=n] [--init-timeout=n] [--strict-paths]
+             [--base-path=path] [directory...]
 
 DESCRIPTION
 -----------
@@ -36,6 +37,14 @@ OPTIONS
 	git-daemon will refuse to start when this option is enabled and no
 	whitelist is specified.
 
+--base-path::
+	Remap all the path requests as relative to the given path.
+	This is sort of "GIT root" - if you run git-daemon with
+	'--base-path=/srv/git' on example.com, then if you later try to pull
+	'git://example.com/hello.git', `git-daemon` will interpret the path
+	as '/srv/git/hello.git'. Home directories (the '~login' notation)
+	access is disabled.
+
 --export-all::
 	Allow pulling from all directories that look like GIT repositories
 	(have the 'objects' and 'refs' subdirectories), even if they

daemon.c

@@ -15,7 +15,8 @@ static int verbose;
 
 static const char daemon_usage[] =
 "git-daemon [--verbose] [--syslog] [--inetd | --port=n] [--export-all]\n"
-"           [--timeout=n] [--init-timeout=n] [--strict-paths] [directory...]";
+"           [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
+"           [--base-path=path] [directory...]";
 
 /* List of acceptable pathname prefixes */
 static char **ok_paths = NULL;
@@ -24,6 +25,9 @@ static int strict_paths = 0;
 /* If this is set, git-daemon-export-ok is not required */
 static int export_all_trees = 0;
 
+/* Take all paths relative to this one if non-NULL */
+static char *base_path = NULL;
+
 /* Timeout, and initial timeout */
 static unsigned int timeout = 0;
 static unsigned int init_timeout = 0;
@@ -138,6 +142,17 @@ static char *path_ok(char *dir)
 		return NULL;
 	}
 
+	if (base_path) {
+		static char rpath[PATH_MAX];
+		if (*dir != '/') {
+			/* Forbid possible base-path evasion using ~paths. */
+			logerror("'%s': Non-absolute path denied (base-path active)");
+			return NULL;
+		}
+		snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
+		dir = rpath;
+	}
+
 	path = enter_repo(dir, strict_paths);
 
 	if (!path) {
@@ -639,6 +654,10 @@ int main(int argc, char **argv)
 			strict_paths = 1;
 			continue;
 		}
+		if (!strncmp(arg, "--base-path=", 12)) {
+			base_path = arg+12;
+			continue;
+		}
 		if (!strcmp(arg, "--")) {
 			ok_paths = &argv[i+1];
 			break;