[PATCH] Allow git-shell to be used as a ssh forced-command

[Mike Hommey <mh@glandium.org>]

When using a forced-command, OpenSSH sets the SSH_ORIGINAL_COMMAND
variable to what would otherwise be passed to $SHELL -c. When this
variable is set, we use it instead of the contents of argv.

Signed-off-by: Mike Hommey <mh@glandium.org>
---

I was unsure whether I needed to give more information about
forced-commands in the commit message itself, anyways, just in case
you don't know what it is:
http://oreilly.com/catalog/sshtdg/chapter/ch08.html#22858

I'm not sure if it's worth adding a check for SSH2_ORIGINAL_COMMAND.
Are people using the commercial SSH2 ?

 shell.c |   29 +++++++++++++++++------------
 1 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/shell.c b/shell.c
index e339369..14ff266 100644
--- a/shell.c
+++ b/shell.c
@@ -62,20 +62,25 @@ int main(int argc, char **argv)
 		die("opening /dev/null failed (%s)", strerror(errno));
 	close (devnull_fd);
 
-	/*
-	 * Special hack to pretend to be a CVS server
-	 */
-	if (argc == 2 && !strcmp(argv[1], "cvs server"))
-		argv--;
+	/* Use original command if we were run from a ssh forced-command */
+	prog = getenv("SSH_ORIGINAL_COMMAND");
+	if (!prog) {
+		/*
+		 * Special hack to pretend to be a CVS server
+		 */
+		if (argc == 2 && !strcmp(argv[1], "cvs server"))
+			argv--;
 
-	/*
-	 * We do not accept anything but "-c" followed by "cmd arg",
-	 * where "cmd" is a very limited subset of git commands.
-	 */
-	else if (argc != 3 || strcmp(argv[1], "-c"))
-		die("What do you think I am? A shell?");
+		/*
+		 * We do not accept anything but "-c" followed by "cmd arg",
+		 * where "cmd" is a very limited subset of git commands.
+		 */
+		else if (argc != 3 || strcmp(argv[1], "-c"))
+			die("What do you think I am? A shell?");
+
+		prog = argv[2];
+	}
 
-	prog = argv[2];
 	if (!strncmp(prog, "git", 3) && isspace(prog[3]))
 		/* Accept "git foo" as if the caller said "git-foo". */
 		prog[3] = '-';
-- 
1.6.3.rc0.1.g8bd72.dirty