refs: don't dereference on rename

When renaming refs, don't dereference either the origin or the destination
before renaming.

The origin does not need to be dereferenced because it is presently
forbidden to rename symbolic refs.

Not dereferencing the destination fixes a bug where renaming on top of
a broken symref would use the pointed-to ref name for the moved
reflog.

Add a test for the reflog bug.

Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 2f98eebe94e1a7ca42b2999eeb3868e2b7096a39..15ba456d68062ed15cb96454008b8c57f1f192e9 100644 (file)
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2333,7 +2333,8 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        if (log && S_ISLNK(loginfo.st_mode))
                return error("reflog for %s is a symlink", oldrefname);
 
-       if (!resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING, orig_sha1, &flag))
+       if (!resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
+                               orig_sha1, &flag))
                return error("refname %s not found", oldrefname);
 
        if (flag & REF_ISSYMREF)
@@ -2351,8 +2352,16 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
                goto rollback;
        }
 
-       if (!read_ref_full(newrefname, RESOLVE_REF_READING, sha1, NULL) &&
-           delete_ref(newrefname, sha1, REF_NODEREF)) {
+       /*
+        * Since we are doing a shallow lookup, sha1 is not the
+        * correct value to pass to delete_ref as old_sha1. But that
+        * doesn't matter, because an old_sha1 check wouldn't add to
+        * the safety anyway; we want to delete the reference whatever
+        * its current value.
+        */
+       if (!read_ref_full(newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
+                          sha1, NULL) &&
+           delete_ref(newrefname, NULL, REF_NODEREF)) {
                if (errno==EISDIR) {
                        struct strbuf path = STRBUF_INIT;
                        int result;
@@ -2376,7 +2385,8 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 
        logmoved = log;
 
-       lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, 0, NULL, &err);
+       lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, REF_NODEREF,
+                                  NULL, &err);
        if (!lock) {
                error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
                strbuf_release(&err);
@@ -2394,7 +2404,8 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
        return 0;
 
  rollback:
-       lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, 0, NULL, &err);
+       lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, REF_NODEREF,
+                                  NULL, &err);
        if (!lock) {
                error("unable to lock %s for rollback: %s", oldrefname, err.buf);
                strbuf_release(&err);

diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index f3e3b6cf2eabf0d57f64d794dba9a6195e8da246..42811604bb8346950e273add0f35020ab73c9599 100755 (executable)
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -79,6 +79,15 @@ test_expect_success 'git branch -m dumps usage' '
        test_i18ngrep "branch name required" err
 '
 
+test_expect_success 'git branch -m m broken_symref should work' '
+       test_when_finished "git branch -D broken_symref" &&
+       git branch -l m &&
+       git symbolic-ref refs/heads/broken_symref refs/heads/i_am_broken &&
+       git branch -m m broken_symref &&
+       git reflog exists refs/heads/broken_symref &&
+       test_must_fail git reflog exists refs/heads/i_am_broken
+'
+
 test_expect_success 'git branch -m m m/m should work' '
        git branch -l m &&
        git branch -m m m/m &&