branch -d: avoid repeated symref resolution

If a repository gets in a broken state with too much symref nesting,
it cannot be repaired with "git branch -d":

 $ git symbolic-ref refs/heads/nonsense refs/heads/nonsense
 $ git branch -d nonsense
 error: branch 'nonsense' not found.

Worse, "git update-ref --no-deref -d" doesn't work for such repairs
either:

 $ git update-ref -d refs/heads/nonsense
 error: unable to resolve reference refs/heads/nonsense: Too many levels of symbolic links

Fix both by teaching resolve_ref_unsafe a new RESOLVE_REF_NO_RECURSE
flag and passing it when appropriate.

Callers can still read the value of a symref (for example to print a
message about it) with that flag set --- resolve_ref_unsafe will
resolve one level of symrefs and stop there.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Reviewed-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/branch.c b/builtin/branch.c
index 6491bacd69da9585967c22a694fb520aff05d5b4..2ad2d0b44a3b79dd7707f497e96f9e39c7fc91c7 100644 (file)
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -236,7 +236,8 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
                free(name);
 
                name = mkpathdup(fmt, bname.buf);
-               target = resolve_ref_unsafe(name, 0, sha1, &flags);
+               target = resolve_ref_unsafe(name, RESOLVE_REF_NO_RECURSE,
+                                           sha1, &flags);
                if (!target ||
                    (!(flags & REF_ISSYMREF) && is_null_sha1(sha1))) {
                        error(remote_branch

diff --git a/cache.h b/cache.h
index 720063968b62b670f97e4fec9b897466d4e78d87..b735f3f1e38a6c671aaecac278d12b4ce4e2b4f4 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -973,6 +973,11 @@ extern int read_ref(const char *refname, unsigned char *sha1);
  *   "writing" to the ref, the return value is the name of the ref
  *   that will actually be created or changed.
  *
+ * If the RESOLVE_REF_NO_RECURSE flag is passed, only resolves one
+ * level of symbolic reference.  The value stored in sha1 for a symbolic
+ * reference will always be null_sha1 in this case, and the return
+ * value is the reference that the symref refers to directly.
+ *
  * If flags is non-NULL, set the value that it points to the
  * combination of REF_ISPACKED (if the reference was found among the
  * packed references), REF_ISSYMREF (if the initial reference was a
@@ -985,6 +990,7 @@ extern int read_ref(const char *refname, unsigned char *sha1);
  * errno is set to something meaningful on error.
  */
 #define RESOLVE_REF_READING 0x01
+#define RESOLVE_REF_NO_RECURSE 0x02
 extern const char *resolve_ref_unsafe(const char *ref, int resolve_flags, unsigned char *sha1, int *flags);
 extern char *resolve_refdup(const char *ref, int resolve_flags, unsigned char *sha1, int *flags);
 

diff --git a/refs.c b/refs.c
index f8d59ab7f004a336b92dd2355ef4a518cef3231a..4fe263ef9a5806307d4faa0641c7e7361bca4e0f 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1467,6 +1467,10 @@ const char *resolve_ref_unsafe(const char *refname, int resolve_flags, unsigned
                                refname = refname_buffer;
                                if (flags)
                                        *flags |= REF_ISSYMREF;
+                               if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
+                                       hashclr(sha1);
+                                       return refname;
+                               }
                                continue;
                        }
                }
@@ -1523,13 +1527,17 @@ const char *resolve_ref_unsafe(const char *refname, int resolve_flags, unsigned
                buf = buffer + 4;
                while (isspace(*buf))
                        buf++;
+               refname = strcpy(refname_buffer, buf);
+               if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
+                       hashclr(sha1);
+                       return refname;
+               }
                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
                        if (flags)
                                *flags |= REF_ISBROKEN;
                        errno = EINVAL;
                        return NULL;
                }
-               refname = strcpy(refname_buffer, buf);
        }
 }
 
@@ -2170,6 +2178,8 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
        if (mustexist)
                resolve_flags |= RESOLVE_REF_READING;
+       if (flags & REF_NODEREF && flags & REF_DELETING)
+               resolve_flags |= RESOLVE_REF_NO_RECURSE;
 
        refname = resolve_ref_unsafe(refname, resolve_flags,
                                     lock->old_sha1, &type);
@@ -3664,13 +3674,16 @@ int ref_transaction_commit(struct ref_transaction *transaction,
        /* Acquire all locks while verifying old values */
        for (i = 0; i < n; i++) {
                struct ref_update *update = updates[i];
+               int flags = update->flags;
 
+               if (is_null_sha1(update->new_sha1))
+                       flags |= REF_DELETING;
                update->lock = lock_ref_sha1_basic(update->refname,
                                                   (update->have_old ?
                                                    update->old_sha1 :
                                                    NULL),
                                                   NULL,
-                                                  update->flags,
+                                                  flags,
                                                   &update->type);
                if (!update->lock) {
                        ret = (errno == ENOTDIR)

diff --git a/refs.h b/refs.h
index eea104478fce285943dc7c4b7f43b9db18e71cee..79802d79c04ccf5c81f9ffb12c662396a6681d6f 100644 (file)
--- a/refs.h
+++ b/refs.h
@@ -177,10 +177,12 @@ extern int peel_ref(const char *refname, unsigned char *sha1);
  * ref_transaction_create(), etc.
  * REF_NODEREF: act on the ref directly, instead of dereferencing
  *              symbolic references.
+ * REF_DELETING: tolerate broken refs
  *
  * Flags >= 0x100 are reserved for internal use.
  */
 #define REF_NODEREF    0x01
+#define REF_DELETING   0x02
 /*
  * This function sets errno to something meaningful on failure.
  */

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 0218e96366ddd8659d5a78b42ffcfd415013114c..7c8c41a1a0f063a068ce793a95cadf22b131e80b 100755 (executable)
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -110,6 +110,40 @@ test_expect_success "delete symref without dereference when the referred ref is
 cp -f .git/HEAD.orig .git/HEAD
 git update-ref -d $m
 
+test_expect_success 'update-ref -d is not confused by self-reference' '
+       git symbolic-ref refs/heads/self refs/heads/self &&
+       test_when_finished "rm -f .git/refs/heads/self" &&
+       test_path_is_file .git/refs/heads/self &&
+       test_must_fail git update-ref -d refs/heads/self &&
+       test_path_is_file .git/refs/heads/self
+'
+
+test_expect_success 'update-ref --no-deref -d can delete self-reference' '
+       git symbolic-ref refs/heads/self refs/heads/self &&
+       test_when_finished "rm -f .git/refs/heads/self" &&
+       test_path_is_file .git/refs/heads/self &&
+       git update-ref --no-deref -d refs/heads/self &&
+       test_path_is_missing .git/refs/heads/self
+'
+
+test_expect_success 'update-ref --no-deref -d can delete reference to bad ref' '
+       >.git/refs/heads/bad &&
+       test_when_finished "rm -f .git/refs/heads/bad" &&
+       git symbolic-ref refs/heads/ref-to-bad refs/heads/bad &&
+       test_when_finished "rm -f .git/refs/heads/ref-to-bad" &&
+       test_path_is_file .git/refs/heads/ref-to-bad &&
+       git update-ref --no-deref -d refs/heads/ref-to-bad &&
+       test_path_is_missing .git/refs/heads/ref-to-bad
+'
+
+test_expect_success 'update-ref --no-deref -d can delete reference to broken name' '
+       git symbolic-ref refs/heads/badname refs/heads/broken...ref &&
+       test_when_finished "rm -f .git/refs/heads/badname" &&
+       test_path_is_file .git/refs/heads/badname &&
+       git update-ref --no-deref -d refs/heads/badname &&
+       test_path_is_missing .git/refs/heads/badname
+'
+
 test_expect_success '(not) create HEAD with old sha1' "
        test_must_fail git update-ref HEAD $A $B
 "

diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index ac31b711f29139470308d9062fea33259cf004ab..432921b6b81684313c6b0041a288749c30fdee8e 100755 (executable)
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -285,6 +285,15 @@ test_expect_success 'deleting a dangling symref' '
        test_i18ncmp expect actual
 '
 
+test_expect_success 'deleting a self-referential symref' '
+       git symbolic-ref refs/heads/self-reference refs/heads/self-reference &&
+       test_path_is_file .git/refs/heads/self-reference &&
+       echo "Deleted branch self-reference (was refs/heads/self-reference)." >expect &&
+       git branch -d self-reference >actual &&
+       test_path_is_missing .git/refs/heads/self-reference &&
+       test_i18ncmp expect actual
+'
+
 test_expect_success 'renaming a symref is not allowed' '
        git symbolic-ref refs/heads/master2 refs/heads/master &&
        test_must_fail git branch -m master2 master3 &&