git-bisect.sh: don't accidentally override existing branch "bisect"

If a branch named "bisect" or "new-bisect" already was created in the
repo by other means than git bisect, doing a git bisect used to override
the branch without a warning.  Now if the branch "bisect" or
"new-bisect" already exists, and it was not created by git bisect itself,
git bisect start fails with an appropriate error message.  Additionally,
if checking out a new bisect state fails due to a merge problem, git
bisect cleans up the temporary branch "new-bisect".

The accidental override has been noticed by Andres Salomon, reported
through
 http://bugs.debian.org/478647

Signed-off-by: Gerrit Pape <pape@smarden.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-bisect.txt b/Documentation/git-bisect.txt
index 96585ae8d9455654b63e83d61e7c34a7aeb94291..0855b98b281c95830850b01a3db59a1ceb8f6eb2 100644 (file)
--- a/Documentation/git-bisect.txt
+++ b/Documentation/git-bisect.txt
@@ -78,7 +78,7 @@ Oh, and then after you want to reset to the original head, do a
 $ git bisect reset
 ------------------------------------------------
 
-to get back to the master branch, instead of being in one of the
+to get back to the original branch, instead of being in one of the
 bisection branches ("git bisect start" will do that for you too,
 actually: it will reset the bisection state, and before it does that
 it checks that you're not using some old bisection branch).

diff --git a/git-bisect.sh b/git-bisect.sh
index 8e57e9a75dd9916d2c5a59f224859d1a22854c7f..54bfd71dad0c2f587de68742945ca52909df0c95 100755 (executable)
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -65,14 +65,19 @@ bisect_start() {
        head=$(GIT_DIR="$GIT_DIR" git symbolic-ref -q HEAD) ||
        head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) ||
        die "Bad HEAD - I need a HEAD"
+       #
+       # Check that we either already have BISECT_START, or that the
+       # branches bisect, new-bisect don't exist, to not override them.
+       #
+       test -s "$GIT_DIR/BISECT_START" ||
+               if git show-ref --verify -q refs/heads/bisect ||
+                   git show-ref --verify -q refs/heads/new-bisect; then
+                       die 'The branches "bisect" and "new-bisect" must not exist.'
+               fi
        start_head=''
        case "$head" in
        refs/heads/bisect)
-               if [ -s "$GIT_DIR/BISECT_START" ]; then
-                   branch=`cat "$GIT_DIR/BISECT_START"`
-               else
-                   branch=master
-               fi
+               branch=`cat "$GIT_DIR/BISECT_START"`
                git checkout $branch || exit
                ;;
        refs/heads/*|$_x40)
@@ -324,8 +329,8 @@ bisect_next() {
        exit_if_skipped_commits "$bisect_rev"
 
        echo "Bisecting: $bisect_nr revisions left to test after this"
-       git branch -f new-bisect "$bisect_rev"
-       git checkout -q new-bisect || exit
+       git branch -D new-bisect 2> /dev/null
+       git checkout -q -b new-bisect "$bisect_rev" || exit
        git branch -M new-bisect bisect
        git show-branch "$bisect_rev"
 }

diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
index 5e3e5445c730140ad6c2fa9cc5bda4a7029e7fbf..05f1e15c34cab66743d48b365479a000d641b23b 100755 (executable)
--- a/t/t6030-bisect-porcelain.sh
+++ b/t/t6030-bisect-porcelain.sh
@@ -284,6 +284,24 @@ test_expect_success 'bisect starting with a detached HEAD' '
 
 '
 
+test_expect_success 'bisect refuses to start if branch bisect exists' '
+       git bisect reset &&
+       git branch bisect &&
+       test_must_fail git bisect start &&
+       git branch -d bisect &&
+       git checkout -b bisect &&
+       test_must_fail git bisect start &&
+       git checkout master &&
+       git branch -d bisect
+'
+
+test_expect_success 'bisect refuses to start if branch new-bisect exists' '
+       git bisect reset &&
+       git branch new-bisect &&
+       test_must_fail git bisect start &&
+       git branch -d new-bisect
+'
+
 #
 #
 test_done