reflog_expire(): ignore --updateref for symbolic references

If we are expiring reflog entries for a symbolic reference, then how
should --updateref be handled if the newest reflog entry is expired?

Option 1: Update the referred-to reference. (This is what the current
code does.) This doesn't make sense, because the referred-to reference
has its own reflog, which hasn't been rewritten.

Option 2: Update the symbolic reference itself (as in, REF_NODEREF).
This would convert the symbolic reference into a non-symbolic
reference (e.g., detaching HEAD), which is surely not what a user
would expect.

Option 3: Error out. This is plausible, but it would make the
following usage impossible:

git reflog expire ... --updateref --all

Option 4: Ignore --updateref for symbolic references.

We choose to implement option 4.

Note: another problem in this code will be fixed in a moment.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-reflog.txt b/Documentation/git-reflog.txt
index 730106c90a18f275523c2c03ac3a16d7347636b0..5e7908e4f705d858dca8483069fd3b89c8f7e31c 100644 (file)
--- a/Documentation/git-reflog.txt
+++ b/Documentation/git-reflog.txt
@@ -88,7 +88,8 @@ Options for `expire`
 
 --updateref::
        Update the reference to the value of the top reflog entry (i.e.
-       <ref>@\{0\}) if the previous top entry was pruned.
+       <ref>@\{0\}) if the previous top entry was pruned.  (This
+       option is ignored for symbolic references.)
 
 --rewrite::
        If a reflog entry's predecessor is pruned, adjust its "old"

diff --git a/refs.c b/refs.c
index 5d8d57d3490a045e23e511088af8f789d7b537da..4684ffe2a6ff7c749aa0c51389c7ee9bb5024c7a 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -4029,6 +4029,7 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
        struct ref_lock *lock;
        char *log_file;
        int status = 0;
+       int type;
 
        memset(&cb, 0, sizeof(cb));
        cb.flags = flags;
@@ -4040,7 +4041,7 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
         * reference itself, plus we might need to update the
         * reference if --updateref was specified:
         */
-       lock = lock_ref_sha1_basic(refname, sha1, NULL, 0, NULL);
+       lock = lock_ref_sha1_basic(refname, sha1, NULL, 0, &type);
        if (!lock)
                return error("cannot lock ref '%s'", refname);
        if (!reflog_exists(refname)) {
@@ -4077,10 +4078,18 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
        (*cleanup_fn)(cb.policy_cb);
 
        if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
+               /*
+                * It doesn't make sense to adjust a reference pointed
+                * to by a symbolic ref based on expiring entries in
+                * the symbolic reference's reflog.
+                */
+               int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
+                       !(type & REF_ISSYMREF);
+
                if (close_lock_file(&reflog_lock)) {
                        status |= error("couldn't write %s: %s", log_file,
                                        strerror(errno));
-               } else if ((flags & EXPIRE_REFLOGS_UPDATE_REF) &&
+               } else if (update &&
                        (write_in_full(lock->lock_fd,
                                sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
                         write_str_in_full(lock->lock_fd, "\n") != 1 ||
@@ -4091,7 +4100,7 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
                } else if (commit_lock_file(&reflog_lock)) {
                        status |= error("unable to commit reflog '%s' (%s)",
                                        log_file, strerror(errno));
-               } else if ((flags & EXPIRE_REFLOGS_UPDATE_REF) && commit_ref(lock)) {
+               } else if (update && commit_ref(lock)) {
                        status |= error("couldn't set %s", lock->ref_name);
                }
        }