request-pull: more strictly match local/remote branches

The current 'request-pull' will try to find matching commit on the given
remote, and rewrite the "please pull" line to match that remote ref.

That may be very helpful if your local tree doesn't match the layout of
the remote branches, but for the common case it's been a recurring
disaster, when "request-pull" is done against a delayed remote update, and
it rewrites the target branch randomly to some other branch name that
happens to have the same expected SHA1 (or more commonly, leaves it
blank).

To avoid that recurring problem, this changes "git request-pull" so that
it matches the ref name to be pulled against the *local* repository, and
then warns if the remote repository does not have that exact same branch
or tag name and content.

This means that git request-pull will never rewrite the ref-name you gave
it.  If the local branch name is "xyzzy", that is the only branch name
that request-pull will ask the other side to fetch.

If the remote has that branch under a different name, that's your problem
and git request-pull will not try to fix it up (but git request-pull will
warn about the fact that no exact matching branch is found, and you can
edit the end result to then have the remote name you want if it doesn't
match your local one).

The new "find local ref" code will also complain loudly if you give an
ambiguous refname (eg you have both a tag and a branch with that same
name, and you don't specify "heads/name" or "tags/name").

Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: torvalds

git-request-pull.sh

@@ -35,20 +35,7 @@ do
 	shift
 done
 
-base=$1 url=$2 head=${3-HEAD} status=0 branch_name=
-
-headref=$(git symbolic-ref -q "$head")
-if git show-ref -q --verify "$headref"
-then
-	branch_name=${headref#refs/heads/}
-	if test "z$branch_name" = "z$headref" ||
-		! git config "branch.$branch_name.description" >/dev/null
-	then
-		branch_name=
-	fi
-fi
-
-tag_name=$(git describe --exact "$head^0" 2>/dev/null)
+base=$1 url=$2 status=0
 
 test -n "$base" && test -n "$url" || usage
 
@@ -58,55 +45,68 @@ then
     die "fatal: Not a valid revision: $base"
 fi
 
+#
+# $3 must be a symbolic ref, a unique ref, or
+# a SHA object expression
+#
+head=$(git symbolic-ref -q "${3-HEAD}")
+head=${head:-$(git show-ref "${3-HEAD}" | cut -d' ' -f2)}
+head=${head:-$(git rev-parse --quiet --verify "$3")}
+
+# None of the above? Bad.
+test -z "$head" && die "fatal: Not a valid revision: $3"
+
+# This also verifies that the resulting head is unique:
+# "git show-ref" could have shown multiple matching refs..
 headrev=$(git rev-parse --verify --quiet "$head"^0)
-if test -z "$headrev"
+test -z "$headrev" && die "fatal: Ambiguous revision: $3"
+
+# Was it a branch with a description?
+branch_name=${head#refs/heads/}
+if test "z$branch_name" = "z$headref" ||
+	! git config "branch.$branch_name.description" >/dev/null
 then
-    die "fatal: Not a valid revision: $head"
+	branch_name=
 fi
 
+prettyhead=${head#refs/}
+prettyhead=${prettyhead#heads/}
+
 merge_base=$(git merge-base $baserev $headrev) ||
 die "fatal: No commits in common between $base and $head"
 
-# $head is the token given from the command line, and $tag_name, if
-# exists, is the tag we are going to show the commit information for.
-# If that tag exists at the remote and it points at the commit, use it.
-# Otherwise, if a branch with the same name as $head exists at the remote
-# and their values match, use that instead.
+# $head is the refname from the command line.
+# If a ref with the same name as $head exists at the remote
+# and their values match, use that.
 #
 # Otherwise find a random ref that matches $headrev.
 find_matching_ref='
-	sub abbr {
-		my $ref = shift;
-		if ($ref =~ s|^refs/heads/|| || $ref =~ s|^refs/tags/|tags/|) {
-			return $ref;
-		} else {
-			return $ref;
-		}
-	}
-
-	my ($tagged, $branch, $found);
+	my ($exact,$found);
 	while (<STDIN>) {
-		my ($sha1, $ref, $deref) = /^(\S+)\s+(\S+?)(\^\{\})?$/;
+		my ($sha1, $ref, $deref) = /^(\S+)\s+([^^]+)(\S*)$/;
 		next unless ($sha1 eq $ARGV[1]);
-		$found = abbr($ref);
-		if ($deref && $ref eq "tags/$ARGV[2]") {
-			$tagged = $found;
-			last;
+		if ($ref eq $ARGV[0]) {
+			$exact = $ref;
 		}
-		if ($ref =~ m|/\Q$ARGV[0]\E$|) {
-			$exact = $found;
+		if ($sha1 eq $ARGV[0]) {
+			$found = $sha1;
 		}
 	}
-	if ($tagged) {
-		print "$tagged\n";
-	} elsif ($exact) {
+	if ($exact) {
 		print "$exact\n";
 	} elsif ($found) {
 		print "$found\n";
 	}
 '
 
-ref=$(git ls-remote "$url" | @@PERL@@ -e "$find_matching_ref" "$head" "$headrev" "$tag_name")
+ref=$(git ls-remote "$url" | @@PERL@@ -e "$find_matching_ref" "$head" "$headrev")
+
+if test -z "$ref"
+then
+	echo "warn: No match for $prettyhead found at $url" >&2
+	echo "warn: Are you sure you pushed '$prettyhead' there?" >&2
+	status=1
+fi
 
 url=$(git ls-remote --get-url "$url")
 
@@ -116,7 +116,7 @@ git show -s --format='The following changes since commit %H:
 
 are available in the git repository at:
 ' $merge_base &&
-echo "  $url${ref+ $ref}" &&
+echo "  $url $prettyhead" &&
 git show -s --format='
 for you to fetch changes up to %H:
 
@@ -129,34 +129,10 @@ then
 	echo "(from the branch description for $branch_name local branch)"
 	echo
 	git config "branch.$branch_name.description"
-fi &&
-
-if test -n "$tag_name"
-then
-	if test -z "$ref" || test "$ref" != "tags/$tag_name"
-	then
-		echo >&2 "warn: You locally have $tag_name but it does not (yet)"
-		echo >&2 "warn: appear to be at $url"
-		echo >&2 "warn: Do you want to push it there, perhaps?"
-	fi
-	git cat-file tag "$tag_name" |
-	sed -n -e '1,/^$/d' -e '/^-----BEGIN PGP /q' -e p
-	echo
-fi &&
-
-if test -n "$branch_name" || test -n "$tag_name"
-then
 	echo "----------------------------------------------------------------"
 fi &&
 
 git shortlog ^$baserev $headrev &&
 git diff -M --stat --summary $patch $merge_base..$headrev || status=1
 
-if test -z "$ref"
-then
-	echo "warn: No branch of $url is at:" >&2
-	git show -s --format='warn:   %h: %s' $headrev >&2
-	echo "warn: Are you sure you pushed '$head' there?" >&2
-	status=1
-fi
 exit $status