[PATCH/resend] CVS Server: Support reading base and roots from environment

[Phil Miller <mille121@illinois.edu>]

The Gitosis single-account Git/ssh hosting system runs git commands
through git-shell after confirming that the connecting user is
authorized to access the requested repository. This works well for
upload-pack and receive-pack, which take a repository argument through
git-shell. This doesn't work so well for `cvs server', which is passed
through literally, with no arguments. Allowing arguments risks
sneaking in `--export-all', so that restriction should be maintained.

Despite that, passing a list of repository roots is necessary for
per-user access control by the hosting software, and passing a base
path improves usability without weakening security. Thus,
git-cvsserver needs to come up with these values at runtime by some
other means. Since git-shell preserves the environment for other
purposes, the environment can carry these arguments as well.

Thus, modify git-cvsserver to read $GIT_CVSSERVER_{BASE_PATH,ROOTS} in
the absence of equivalent command line arguments.

Signed-off-by: Phil Miller <mille121@illinois.edu>
---
 git-cvsserver.perl |   21 ++++++++++++++++++++-
 1 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/git-cvsserver.perl b/git-cvsserver.perl
index 6dc45f5..9e58d2a 100755
--- a/git-cvsserver.perl
+++ b/git-cvsserver.perl
@@ -104,6 +104,7 @@ $log->info("--------------- STARTING -----------------");
 my $usage =
     "Usage: git cvsserver [options] [pserver|server] [<directory> ...]\n".
     "    --base-path <path>  : Prepend to requested CVSROOT\n".
+    "                          Can be read from GIT_CVSSERVER_BASE_PATH\n".
     "    --strict-paths      : Don't allow recursing into subdirectories\n".
     "    --export-all        : Don't check for gitcvs.enabled in config\n".
     "    --version, -V       : Print version information and exit\n".
@@ -111,7 +112,8 @@ my $usage =
     "\n".
     "<directory> ... is a list of allowed directories. If no directories\n".
     "are given, all are allowed. This is an additional restriction, gitcvs\n".
-    "access still needs to be enabled by the gitcvs.enabled config option.\n";
+    "access still needs to be enabled by the gitcvs.enabled config option.\n".
+    "Alternately, these directories may be specified in
GIT_CVSSERVER_ROOTS.\n";

 my @opts = ( 'help|h|H', 'version|V',
 	     'base-path=s', 'strict-paths', 'export-all' );
@@ -148,6 +150,23 @@ if ($state->{'export-all'} &&
!@{$state->{allowed_roots}}) {
     die "--export-all can only be used together with an explicit whitelist\n";
 }

+# Environment handling for running under git-shell
+if ($ENV{GIT_CVSSERVER_BASE_PATH}) {
+    if ($state->{'base-path'}) {
+	die "Cannot specify base path both ways.\n";
+    }
+    my $base_path = $ENV{GIT_CVSSERVER_BASE_PATH};
+    $state->{'base-path'} = $base_path;
+    $log->debug("Picked up base path '$base_path' from environment.\n");
+}
+if ($ENV{GIT_CVSSERVER_ROOTS}) {
+    if (@{$state->{allowed_roots}}) {
+	die "Cannot specify roots both ways: @ARGV\n";
+    }
+    my @allowed_root = split(',', $ENV{GIT_CVSSERVER_ROOTS});
+    $state->{allowed_roots} = [ @allowed_root ];
+}
+
 # if we are called with a pserver argument,
 # deal with the authentication cat before entering the
 # main loop
-- 
1.5.6.3