[PATCH 3/3] update a few Porcelain-ish for ref lock safety.

From

Junio C Hamano <junkio@cox.net>

Date

Sep 26, 2006, 18:05 UTC

Message-ID

<7vu02uqzaj.fsf@assigned-by-dhcp.cox.net>

In-Reply-To

<7vmz8o1em0.fsf_-_@assigned-by-dhcp.cox.net>

 - git-tag makes sure that the named tag does not exist, allows
   you to edit tag message and then creates the tag.  If a tag
   with the same name was created by somebody else in the
   meantime, it used to happily overwrote it.  Now it notices
   the situation.

 - git-branch -d and git-commit (for the initial commit) had the
   same issue but with smaller race window, which is plugged
   with this.

Signed-off-by: Junio C Hamano <junkio@cox.net>
---

 * Obviously I would need to update this on top of Linus's
   packed-refs, but this 3-patch series applies on top of the
   current "master". 

 git-branch.sh |    9 ++++++---
 git-commit.sh |    2 +-
 git-tag.sh    |    9 ++++++---
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/git-branch.sh b/git-branch.sh
index e0501ec..2b58d20 100755
--- a/git-branch.sh
+++ b/git-branch.sh
@@ -42,8 +42,7 @@ If you are sure you want to delete it, r
 	    esac
 	    ;;
 	esac
-	rm -f "$GIT_DIR/logs/refs/heads/$branch_name"
-	rm -f "$GIT_DIR/refs/heads/$branch_name"
+	git update-ref -d "refs/heads/$branch_name" "$branch"
 	echo "Deleted branch $branch_name."
     done
     exit 0
@@ -112,6 +111,7 @@ rev=$(git-rev-parse --verify "$head") ||
 git-check-ref-format "heads/$branchname" ||
 	die "we do not like '$branchname' as a branch name."
 
+prev=0000000000000000000000000000000000000000
 if [ -e "$GIT_DIR/refs/heads/$branchname" ]
 then
 	if test '' = "$force"
@@ -121,10 +121,13 @@ then
 	then
 		die "cannot force-update the current branch."
 	fi
+	prev=`git rev-parse --verify "refs/heads/$branchname"`
 fi
 if test "$create_log" = 'yes'
 then
 	mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$branchname")
 	touch "$GIT_DIR/logs/refs/heads/$branchname"
 fi
-git update-ref -m "branch: Created from $head" "refs/heads/$branchname" $rev
+git update-ref -m "branch: Created from $head" \
+	"refs/heads/$branchname" $rev $prev
+
diff --git a/git-commit.sh b/git-commit.sh
index 5a4c659..87b13ef 100755
--- a/git-commit.sh
+++ b/git-commit.sh
@@ -554,8 +554,8 @@ else
 		exit 1
 	fi
 	PARENTS=""
-	current=
 	rloga='commit (initial)'
+	current=0000000000000000000000000000000000000000
 fi
 
 if test -z "$no_edit"
diff --git a/git-tag.sh b/git-tag.sh
index a0afa25..2bde3c0 100755
--- a/git-tag.sh
+++ b/git-tag.sh
@@ -63,8 +63,11 @@ done
 
 name="$1"
 [ "$name" ] || usage
-if [ -e "$GIT_DIR/refs/tags/$name" -a -z "$force" ]; then
-    die "tag '$name' already exists"
+prev=0000000000000000000000000000000000000000
+if test -e "$GIT_DIR/refs/tags/$name"
+then
+    test -n "$force" || die "tag '$name' already exists"
+    prev=`git rev-parse "refs/tags/$name"`
 fi
 shift
 git-check-ref-format "tags/$name" ||
@@ -109,4 +112,4 @@ fi
 
 leading=`expr "refs/tags/$name" : '\(.*\)/'` &&
 mkdir -p "$GIT_DIR/$leading" &&
-echo $object > "$GIT_DIR/refs/tags/$name"
+GIT_DIR="$GIT_DIR" git update-ref "refs/tags/$name" "$object" "$prev"

-- 
1.4.2.1.g7a39b