git-fetch: resolve remote symrefs for HTTP transport

git-fetch validates that a remote ref resolves to a SHA1 prior to calling
git-http-fetch.  This adds support for resolving a few levels of symrefs
to get to the SHA1.

Signed-off-by: Nick Hengeveld <nickh@reactrix.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/git-fetch.sh b/git-fetch.sh
index 83143f8..280f62e 100755 (executable)
--- a/git-fetch.sh
+++ b/git-fetch.sh
@@ -270,14 +270,22 @@ fetch_main () {
          if [ -n "$GIT_SSL_NO_VERIFY" ]; then
              curl_extra_args="-k"
          fi
-         remote_name_quoted=$(perl -e '
+         max_depth=5
+         depth=0
+         head="ref: $remote_name"
+         while (expr "z$head" : "zref:" && expr $depth \< $max_depth) >/dev/null
+         do
+           remote_name_quoted=$(perl -e '
              my $u = $ARGV[0];
+              $u =~ s/^ref:\s*//;
              $u =~ s{([^-a-zA-Z0-9/.])}{sprintf"%%%02x",ord($1)}eg;
              print "$u";
-         ' "$remote_name")
-         head=$(curl -nsfL $curl_extra_args "$remote/$remote_name_quoted") &&
+         ' "$head")
+           head=$(curl -nsfL $curl_extra_args "$remote/$remote_name_quoted")
+           depth=$( expr \( $depth + 1 \) )
+         done
          expr "z$head" : "z$_x40\$" >/dev/null ||
-                 die "Failed to fetch $remote_name from $remote"
+             die "Failed to fetch $remote_name from $remote"
          echo >&2 Fetching "$remote_name from $remote" using http
          git-http-fetch -v -a "$head" "$remote/" || exit
          ;;