[PATCH v3 00/16] ref-transaction-rename

[PATCH v3 00/16] ref-transaction-rename

[Ronnie Sahlberg]

List,

Thsi series builds on the previous series : ref-transaction-reflog
as applied to next. This series has been sent to the list before
but is now rebased to current git next.

This series can also be found at :
https://github.com/rsahlberg/git/tree/ref-transactions-rename

This series converts ref rename to use a transaction. This addesses several
issues in the old implementation, such as colliding renames might overwrite
someone elses reflog, and it makes the rename atomic.

As part of the series we also move changes that cover multiple refs to happen
as an atomic transaction/rename to the pacekd refs file. This makes it possible
to have both the rename case (one deleted ref + one created ref) as well
as any operation that updates multiple refs to become one atomic rename()
applied to the packed refs file. Thus all such changes are now also atomic
to all external observers.

Version 2:
- Changed to not use potentially iterators to copy the reflog entries one
  by one. Instead adding two new functions. One to read an existing reflog
  as one big blob, and a second function to, in a transaction, write a new
  complete reflog from said blob.
  The idea is that each future reflog backend will provide optimized
  versions for these "read whole reflog" "write whole reflog" functions.

Version 3:
- Rename and redo the API for updating a whole reflog in one single operation
  to transaction_rename_reflog()

Ronnie Sahlberg (16):
  refs.c: allow passing raw git_committer_info as email to
    _update_reflog
  refs.c: return error instead of dying when locking fails during
    transaction
  refs.c: use packed refs when deleting refs during a transaction
  refs.c: use a stringlist for repack_without_refs
  refs.c: add transaction support for renaming a reflog
  refs.c: update rename_ref to use a transaction
  refs.c: rollback the lockfile before we die() in repack_without_refs
  refs.c: move reflog updates into its own function
  refs.c: write updates to packed refs when a transaction has more than
    one ref
  remote.c: use a transaction for deleting refs
  refs.c: make repack_without_refs static
  refs.c: make the *_packed_refs functions static
  refs.c: replace the onerr argument in update_ref with a strbuf err
  refs.c: make add_packed_ref return an error instead of calling die
  refs.c: make lock_packed_refs take an err argument
  refs.c: add an err argument to pack_refs

 builtin/checkout.c    |   7 +-
 builtin/clone.c       |  36 ++-
 builtin/merge.c       |  20 +-
 builtin/notes.c       |  24 +-
 builtin/pack-refs.c   |   8 +-
 builtin/reflog.c      |  19 +-
 builtin/remote.c      |  69 +++---
 builtin/reset.c       |  12 +-
 builtin/update-ref.c  |   7 +-
 notes-cache.c         |   2 +-
 notes-utils.c         |   5 +-
 refs.c                | 616 ++++++++++++++++++++++++++++++--------------------
 refs.h                |  79 +++----
 t/t3200-branch.sh     |   7 -
 t/t5516-fetch-push.sh |   2 +-
 transport-helper.c    |   7 +-
 transport.c           |   9 +-
 17 files changed, 552 insertions(+), 377 deletions(-)

-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 01/16] refs.c: allow passing raw git_committer_info as email to _update_reflog

[Ronnie Sahlberg]

In many places in the code we do not have access to the individual fields
in the committer data. Instead we might only have access to prebaked data
such as what is returned by git_committer_info() containing a string
that consists of email, timestamp, zone etc.

This makes it inconvenient to use transaction_update_reflog since it means
you would have to first parse git_committer_info before you can call
update_reflog.

Add a new flag REFLOG_COMMITTER_INFO_IS_VALID to _update_reflog to tell it
that we pass in a fully prebaked committer info string that can be used as is.

At the same time, also go over and change all references from email
to id where the code actually refers to a committer id and not just an email
address. I.e. where the string is : NAME <EMAIL>

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 builtin/reflog.c | 19 +++++++++++++------
 refs.c           | 21 ++++++++++++---------
 refs.h           | 25 +++++++++++++++++++++++--
 3 files changed, 48 insertions(+), 17 deletions(-)

diff --git a/builtin/reflog.c b/builtin/reflog.c
index 6bb7454..be88a53 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -292,7 +292,7 @@ static int unreachable(struct expire_reflog_cb *cb, struct commit *commit, unsig
 }
 
 static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
-		const char *email, unsigned long timestamp, int tz,
+		const char *id, unsigned long timestamp, int tz,
 		const char *message, void *cb_data)
 {
 	struct expire_reflog_cb *cb = cb_data;
@@ -320,9 +320,14 @@ static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 		goto prune;
 
 	if (cb->t) {
+		struct reflog_committer_info ci;
+
+		memset(&ci, 0, sizeof(ci));
+		ci.id = id;
+		ci.timestamp = timestamp;
+		ci.tz = tz;
 		if (transaction_update_reflog(cb->t, cb->refname, nsha1, osha1,
-					      email, timestamp, tz, message, 0,
-					      &err))
+					      &ci, message, 0, &err))
 			return -1;
 		hashcpy(cb->last_kept_sha1, nsha1);
 	}
@@ -356,6 +361,7 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
 	struct expire_reflog_cb cb;
 	struct commit *tip_commit;
 	struct commit_list *tips;
+	struct reflog_committer_info ci;
 	int status = 0;
 
 	memset(&cb, 0, sizeof(cb));
@@ -368,9 +374,10 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
 		status |= error("%s", err.buf);
 		goto cleanup;
 	}
+
+	memset(&ci, 0, sizeof(ci));
 	if (transaction_update_reflog(cb.t, cb.refname, null_sha1, null_sha1,
-				      NULL, 0, 0, NULL, REFLOG_TRUNCATE,
-				      &err)) {
+				      &ci, NULL, REFLOG_TRUNCATE, &err)) {
 		status |= error("%s", err.buf);
 		goto cleanup;
 	}
@@ -672,7 +679,7 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 }
 
 static int count_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
-		const char *email, unsigned long timestamp, int tz,
+		const char *id, unsigned long timestamp, int tz,
 		const char *message, void *cb_data)
 {
 	struct cmd_reflog_expire_cb *cb = cb_data;
diff --git a/refs.c b/refs.c
index f1ca9e4..1791166 100644
--- a/refs.c
+++ b/refs.c
@@ -3226,7 +3226,7 @@ struct read_ref_at_cb {
 };
 
 static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
-		const char *email, unsigned long timestamp, int tz,
+		const char *id, unsigned long timestamp, int tz,
 		const char *message, void *cb_data)
 {
 	struct read_ref_at_cb *cb = cb_data;
@@ -3273,7 +3273,7 @@ static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
 }
 
 static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
-				  const char *email, unsigned long timestamp,
+				  const char *id, unsigned long timestamp,
 				  int tz, const char *message, void *cb_data)
 {
 	struct read_ref_at_cb *cb = cb_data;
@@ -3625,8 +3625,7 @@ int transaction_update_reflog(struct transaction *transaction,
 			      const char *refname,
 			      const unsigned char *new_sha1,
 			      const unsigned char *old_sha1,
-			      const char *email,
-			      unsigned long timestamp, int tz,
+			      struct reflog_committer_info *ci,
 			      const char *msg, int flags,
 			      struct strbuf *err)
 {
@@ -3654,13 +3653,17 @@ int transaction_update_reflog(struct transaction *transaction,
 	hashcpy(update->new_sha1, new_sha1);
 	hashcpy(update->old_sha1, old_sha1);
 	update->reflog_fd = -1;
-	if (email) {
+	if (flags & REFLOG_COMMITTER_INFO_IS_VALID) {
+		if (!ci->committer_info)
+			die("BUG: committer_info is NULL in reflog update");
+		update->committer = xstrdup(ci->committer_info);
+	} else if (ci->id) {
 		struct strbuf buf = STRBUF_INIT;
-		char sign = (tz < 0) ? '-' : '+';
-		int zone = (tz < 0) ? (-tz) : tz;
+		char sign = (ci->tz < 0) ? '-' : '+';
+		int zone = (ci->tz < 0) ? (-ci->tz) : ci->tz;
 
-		strbuf_addf(&buf, "%s %lu %c%04d", email, timestamp, sign,
-			    zone);
+		strbuf_addf(&buf, "%s %lu %c%04d", ci->id,
+			    ci->timestamp, sign, zone);
 		update->committer = xstrdup(buf.buf);
 		strbuf_release(&buf);
 	}
diff --git a/refs.h b/refs.h
index 2e97f4f..9153e1d 100644
--- a/refs.h
+++ b/refs.h
@@ -318,6 +318,28 @@ int transaction_delete_ref(struct transaction *transaction,
  * Flags >= 0x100 are reserved for internal use.
  */
 #define REFLOG_TRUNCATE 0x01
+#define REFLOG_COMMITTER_INFO_IS_VALID 0x02
+
+/*
+ * Committer data provided to reflog updates.
+ * If flags contain REFLOG_COMMITTER_DATA_IS_VALID then the structure
+ * contains a prebaked committer string just like git_committer_info()
+ * would return.
+ *
+ * If flags does not contain REFLOG_COMMITTER_DATA_IS_VALID
+ * then the committer info string will be generated using the passed
+ * email, timestamp and tz fields.
+ * This is useful for example from reflog iterators where you are passed
+ * these fields individually and not as a prebaked git_committer_info()
+ * string.
+ */
+struct reflog_committer_info {
+	const char *committer_info;
+
+	const char *id;
+	unsigned long timestamp;
+	int tz;
+};
 /*
  * Append a reflog entry for refname. If the REFLOG_TRUNCATE flag is set
  * this update will first truncate the reflog before writing the entry.
@@ -327,8 +349,7 @@ int transaction_update_reflog(struct transaction *transaction,
 			      const char *refname,
 			      const unsigned char *new_sha1,
 			      const unsigned char *old_sha1,
-			      const char *email,
-			      unsigned long timestamp, int tz,
+			      struct reflog_committer_info *ci,
 			      const char *msg, int flags,
 			      struct strbuf *err);
 
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 02/16] refs.c: return error instead of dying when locking fails during transaction

[Ronnie Sahlberg]

Change lock_ref_sha1_basic to return an error instead of dying when
we fail to lock a file during a transaction.
This function is only called from transaction_commit() and it knows how
to handle these failures.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 refs.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/refs.c b/refs.c
index 1791166..d4ab65c 100644
--- a/refs.c
+++ b/refs.c
@@ -2340,6 +2340,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
 	lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 	if (lock->lock_fd < 0) {
+		last_errno = errno;
 		if (errno == ENOENT && --attempts_remaining > 0)
 			/*
 			 * Maybe somebody just deleted one of the
@@ -2347,8 +2348,13 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 			 * again:
 			 */
 			goto retry;
-		else
-			unable_to_lock_die(ref_file, errno);
+		else {
+			struct strbuf err = STRBUF_INIT;
+			unable_to_lock_message(ref_file, errno, &err);
+			error("%s", err.buf);
+			strbuf_reset(&err);
+			goto error_return;
+		}
 	}
 	return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 03/16] refs.c: use packed refs when deleting refs during a transaction

[Ronnie Sahlberg]

Make the deletion of refs during a transaction more atomic.
Start by first copying all loose refs we will be deleting to the packed
refs file and then commit the packed refs file. Then re-lock the packed refs
file to stop anyone else from modifying these refs and keep it locked until
we are finished.
Since all refs we are about to delete are now safely held in the packed refs
file we can proceed to immediately unlink any corresponding loose refs
and still be fully rollback-able.

The exception is for refs that can not be resolved. Those refs are never
added to the packed refs and will just be un-rollback-ably deleted during
commit.

By deleting all the loose refs at the start of the transaction we make make
it possible to both delete one ref and then re-create a different ref in
the same transaction even if the two refs would normally conflict.

Example: rename m->m/m

In that example we want to delete the file 'm' so that we make room so
that we can create a directory with the same name in order to lock and
write to the ref m/m and its lock-file m/m.lock.

If there is a failure during the commit phase we can rollback without losing
any refs since we have so far only deleted loose refs that that are
guaranteed to also have a corresponding entry in the packed refs file.
Once we have finished all updates for refs and their reflogs we can repack
the packed refs file and remove the to-be-deleted refs from the packed refs,
at which point all the deleted refs will disappear in one atomic rename
operation.

This also means that for an outside observer, deletion of multiple refs
in a single transaction will look atomic instead of one ref being deleted
at a time.

In order to do all this we need to change the semantics for the
repack_without_refs function so that we can lock the packed refs file,
do other stuff, and later be able to call repack_without_refs with the
lock already taken.
This means we need some additional changes in remote.c to reflect the
changes to the repack_without_refs semantics.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 builtin/remote.c |  20 ++++++-
 refs.c           | 155 ++++++++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 138 insertions(+), 37 deletions(-)

diff --git a/builtin/remote.c b/builtin/remote.c
index 7f28f92..c25420f 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -1,4 +1,5 @@
 #include "builtin.h"
+#include "lockfile.h"
 #include "parse-options.h"
 #include "transport.h"
 #include "remote.h"
@@ -753,6 +754,15 @@ static int remove_branches(struct string_list *branches)
 	const char **branch_names;
 	int i, result = 0;
 
+	if (lock_packed_refs(0)) {
+		struct strbuf err = STRBUF_INIT;
+
+		unable_to_lock_message(git_path("packed-refs"), errno, &err);
+		error("%s", err.buf);
+		strbuf_release(&err);
+		return -1;
+	}
+
 	branch_names = xmalloc(branches->nr * sizeof(*branch_names));
 	for (i = 0; i < branches->nr; i++)
 		branch_names[i] = branches->items[i].string;
@@ -1337,9 +1347,15 @@ static int prune_remote(const char *remote, int dry_run)
 			delete_refs[i] = states.stale.items[i].util;
 		if (!dry_run) {
 			struct strbuf err = STRBUF_INIT;
-			if (repack_without_refs(delete_refs, states.stale.nr,
-						&err))
+
+			if (lock_packed_refs(0)) {
+				unable_to_lock_message(git_path("packed-refs"),
+						       errno, &err);
 				result |= error("%s", err.buf);
+			} else
+				if (repack_without_refs(delete_refs,
+							states.stale.nr, &err))
+					result |= error("%s", err.buf);
 			strbuf_release(&err);
 		}
 		free(delete_refs);
diff --git a/refs.c b/refs.c
index d4ab65c..809bd3f 100644
--- a/refs.c
+++ b/refs.c
@@ -2660,6 +2660,9 @@ static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
 	return 0;
 }
 
+/*
+ * Must be called with packed refs already locked (and sorted)
+ */
 int repack_without_refs(const char **refnames, int n, struct strbuf *err)
 {
 	struct ref_dir *packed;
@@ -2674,14 +2677,12 @@ int repack_without_refs(const char **refnames, int n, struct strbuf *err)
 		if (get_packed_ref(refnames[i]))
 			break;
 
-	/* Avoid locking if we have nothing to do */
-	if (i == n)
+	/* Avoid processing if we have nothing to do */
+	if (i == n) {
+		rollback_packed_refs();
 		return 0; /* no refname exists in packed refs */
-
-	if (lock_packed_refs(0)) {
-		unable_to_lock_message(git_path("packed-refs"), errno, err);
-		return -1;
 	}
+
 	packed = get_packed_refs(&ref_cache);
 
 	/* Remove refnames from the cache */
@@ -3798,10 +3799,12 @@ static int ref_update_reject_duplicates(struct ref_update **updates, int n,
 int transaction_commit(struct transaction *transaction,
 		       struct strbuf *err)
 {
-	int ret = 0, delnum = 0, i;
+	int ret = 0, delnum = 0, i, need_repack = 0;
 	const char **delnames;
 	int n = transaction->nr;
+	struct packed_ref_cache *packed_ref_cache;
 	struct ref_update **updates = transaction->updates;
+	struct ref_dir *packed;
 
 	assert(err);
 
@@ -3823,23 +3826,109 @@ int transaction_commit(struct transaction *transaction,
 		goto cleanup;
 	}
 
-	/* Acquire all ref locks while verifying old values */
+	/* Lock packed refs during commit */
+	if (lock_packed_refs(0)) {
+		if (err)
+			unable_to_lock_message(git_path("packed-refs"),
+					       errno, err);
+		ret = -1;
+		goto cleanup;
+	}
+
+	/* any loose refs are to be deleted are first copied to packed refs */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
-		int flags = update->flags;
+		unsigned char sha1[20];
 
 		if (update->update_type != UPDATE_SHA1)
 			continue;
+		if (!is_null_sha1(update->new_sha1))
+			continue;
+		if (get_packed_ref(update->refname))
+			continue;
+		if (!resolve_ref_unsafe(update->refname, RESOLVE_REF_READING,
+					sha1, NULL))
+			continue;
 
-		if (is_null_sha1(update->new_sha1))
-			flags |= REF_DELETING;
+		add_packed_ref(update->refname, sha1);
+		need_repack = 1;
+	}
+	if (need_repack) {
+		packed = get_packed_refs(&ref_cache);;
+		sort_ref_dir(packed);
+		if (commit_packed_refs()){
+			strbuf_addf(err, "unable to overwrite old ref-pack "
+				    "file");
+			ret = -1;
+			goto cleanup;
+		}
+		/* lock the packed refs again so no one can change it */
+		if (lock_packed_refs(0)) {
+			if (err)
+				unable_to_lock_message(git_path("packed-refs"),
+						       errno, err);
+			ret = -1;
+			goto cleanup;
+		}
+	}
+
+	/*
+	 * At this stage any refs that are to be deleted have been moved to the
+	 * packed refs file anf the packed refs file is deleted. We can now
+	 * safely delete these loose refs.
+	 */
+
+	/* Unlink any loose refs scheduled for deletion */
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+
+		if (update->update_type != UPDATE_SHA1)
+			continue;
+		if (!is_null_sha1(update->new_sha1))
+			continue;
+		update->flags |= REF_DELETING;
+		update->lock = lock_ref_sha1_basic(update->refname,
+						   (update->have_old ?
+						    update->old_sha1 :
+						    NULL),
+						   NULL,
+						   update->flags,
+						   &update->type);
+		if (!update->lock) {
+			int df_conflict = (errno == ENOTDIR);
+
+			strbuf_addf(err, "Cannot lock the ref '%s'.",
+				    update->refname);
+			ret = df_conflict ?
+			  TRANSACTION_NAME_CONFLICT : 
+			  TRANSACTION_GENERIC_ERROR;
+			goto cleanup;
+		}
+		if (delete_ref_loose(update->lock, update->type, err)) {
+			ret = -1;
+			goto cleanup;
+		}
+		try_remove_empty_parents((char *)update->refname);
+		if (!(update->flags & REF_ISPRUNING))
+			  delnames[delnum++] = xstrdup(update->lock->ref_name);
+		unlock_ref(update->lock);
+		update->lock = NULL;
+	}
+
+	/* Acquire all ref locks for updates while verifying old values */
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
 
+		if (update->update_type != UPDATE_SHA1)
+			continue;
+		if (is_null_sha1(update->new_sha1))
+			continue;
 		update->lock = lock_ref_sha1_basic(update->refname,
 						   (update->have_old ?
 						    update->old_sha1 :
 						    NULL),
 						   NULL,
-						   flags,
+						   update->flags,
 						   &update->type);
 		if (!update->lock) {
 			ret = (errno == ENOTDIR)
@@ -3851,6 +3940,10 @@ int transaction_commit(struct transaction *transaction,
 		}
 	}
 
+	/* delete reflog for all deleted refs */
+	for (i = 0; i < delnum; i++)
+		unlink_or_warn(git_path("logs/%s", delnames[i]));
+
 	/* Lock all reflog files */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
@@ -3862,6 +3955,16 @@ int transaction_commit(struct transaction *transaction,
 			update->reflog_lock = update->orig_update->reflog_lock;
 			continue;
 		}
+		if (log_all_ref_updates && !reflog_exists(update->refname) &&
+		    create_reflog(update->refname)) {
+			ret = -1;
+			if (err)
+				strbuf_addf(err, "Failed to setup reflog for "
+					    "%s", update->refname);
+			goto cleanup;
+		}
+		if (!reflog_exists(update->refname))
+			continue;
 		update->reflog_fd = hold_lock_file_for_append(
 					update->reflog_lock,
 					git_path("logs/%s", update->refname),
@@ -3877,7 +3980,7 @@ int transaction_commit(struct transaction *transaction,
 		}
 	}
 
-	/* Perform ref updates first so live commits remain referenced */
+	/* Perform ref updates */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
 
@@ -3896,23 +3999,6 @@ int transaction_commit(struct transaction *transaction,
 		}
 	}
 
-	/* Perform deletes now that updates are safely completed */
-	for (i = 0; i < n; i++) {
-		struct ref_update *update = updates[i];
-
-		if (update->update_type != UPDATE_SHA1)
-			continue;
-		if (update->lock) {
-			if (delete_ref_loose(update->lock, update->type, err)) {
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto cleanup;
-			}
-
-			if (!(update->flags & REF_ISPRUNING))
-				delnames[delnum++] = update->lock->ref_name;
-		}
-	}
-
 	/*
 	 * Update all reflog files
 	 * We have already committed all ref updates and deletes.
@@ -3963,15 +4049,14 @@ int transaction_commit(struct transaction *transaction,
 		}
 	}
 
-	if (repack_without_refs(delnames, delnum, err)) {
+	if (repack_without_refs(delnames, delnum, err))
 		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-	for (i = 0; i < delnum; i++)
-		unlink_or_warn(git_path("logs/%s", delnames[i]));
 	clear_loose_ref_cache(&ref_cache);
 
 cleanup:
+	packed_ref_cache = get_packed_ref_cache(&ref_cache);
+	if (packed_ref_cache->lock)
+		rollback_packed_refs();
 	transaction->state = TRANSACTION_CLOSED;
 
 	for (i = 0; i < n; i++)
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 04/16] refs.c: use a stringlist for repack_without_refs

[Ronnie Sahlberg]

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/remote.c | 23 ++++++++---------------
 refs.c           | 42 +++++++++++++++++++++---------------------
 refs.h           |  2 +-
 3 files changed, 30 insertions(+), 37 deletions(-)

diff --git a/builtin/remote.c b/builtin/remote.c
index c25420f..6806251 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -751,7 +751,6 @@ static int mv(int argc, const char **argv)
 static int remove_branches(struct string_list *branches)
 {
 	struct strbuf err = STRBUF_INIT;
-	const char **branch_names;
 	int i, result = 0;
 
 	if (lock_packed_refs(0)) {
@@ -763,13 +762,9 @@ static int remove_branches(struct string_list *branches)
 		return -1;
 	}
 
-	branch_names = xmalloc(branches->nr * sizeof(*branch_names));
-	for (i = 0; i < branches->nr; i++)
-		branch_names[i] = branches->items[i].string;
-	if (repack_without_refs(branch_names, branches->nr, &err))
+	if (repack_without_refs(branches, &err))
 		result |= error("%s", err.buf);
 	strbuf_release(&err);
-	free(branch_names);
 
 	for (i = 0; i < branches->nr; i++) {
 		struct string_list_item *item = branches->items + i;
@@ -1327,7 +1322,6 @@ static int prune_remote(const char *remote, int dry_run)
 	int result = 0, i;
 	struct ref_states states;
 	struct string_list delete_refs_list = STRING_LIST_INIT_NODUP;
-	const char **delete_refs;
 	const char *dangling_msg = dry_run
 		? _(" %s will become dangling!")
 		: _(" %s has become dangling!");
@@ -1335,6 +1329,11 @@ static int prune_remote(const char *remote, int dry_run)
 	memset(&states, 0, sizeof(states));
 	get_remote_ref_states(remote, &states, GET_REF_STATES);
 
+	for (i = 0; i < states.stale.nr; i++) {
+		string_list_insert(&delete_refs_list,
+				   states.stale.items[i].util);
+	}
+
 	if (states.stale.nr) {
 		printf_ln(_("Pruning %s"), remote);
 		printf_ln(_("URL: %s"),
@@ -1342,9 +1341,6 @@ static int prune_remote(const char *remote, int dry_run)
 		       ? states.remote->url[0]
 		       : _("(no URL)"));
 
-		delete_refs = xmalloc(states.stale.nr * sizeof(*delete_refs));
-		for (i = 0; i < states.stale.nr; i++)
-			delete_refs[i] = states.stale.items[i].util;
 		if (!dry_run) {
 			struct strbuf err = STRBUF_INIT;
 
@@ -1353,19 +1349,16 @@ static int prune_remote(const char *remote, int dry_run)
 						       errno, &err);
 				result |= error("%s", err.buf);
 			} else
-				if (repack_without_refs(delete_refs,
-							states.stale.nr, &err))
+				if (repack_without_refs(&delete_refs_list,
+							&err))
 					result |= error("%s", err.buf);
 			strbuf_release(&err);
 		}
-		free(delete_refs);
 	}
 
 	for (i = 0; i < states.stale.nr; i++) {
 		const char *refname = states.stale.items[i].util;
 
-		string_list_insert(&delete_refs_list, refname);
-
 		if (!dry_run)
 			result |= delete_ref(refname, NULL, 0);
 
diff --git a/refs.c b/refs.c
index 809bd3f..e9e321e 100644
--- a/refs.c
+++ b/refs.c
@@ -2663,31 +2663,32 @@ static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
 /*
  * Must be called with packed refs already locked (and sorted)
  */
-int repack_without_refs(const char **refnames, int n, struct strbuf *err)
+int repack_without_refs(struct string_list *without, struct strbuf *err)
 {
 	struct ref_dir *packed;
 	struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
 	struct string_list_item *ref_to_delete;
-	int i, ret, removed = 0;
+	int count, ret, removed = 0;
 
 	assert(err);
 
 	/* Look for a packed ref */
-	for (i = 0; i < n; i++)
-		if (get_packed_ref(refnames[i]))
-			break;
+	count = 0;
+	for_each_string_list_item(ref_to_delete, without)
+		if (get_packed_ref(ref_to_delete->string))
+			count++;
 
-	/* Avoid processing if we have nothing to do */
-	if (i == n) {
+	/* No refname exists in packed refs */
+	if (!count) {
 		rollback_packed_refs();
-		return 0; /* no refname exists in packed refs */
+		return 0;
 	}
 
 	packed = get_packed_refs(&ref_cache);
 
 	/* Remove refnames from the cache */
-	for (i = 0; i < n; i++)
-		if (remove_entry(packed, refnames[i]) != -1)
+	for_each_string_list_item(ref_to_delete, without)
+		if (remove_entry(packed, ref_to_delete->string) != -1)
 			removed = 1;
 	if (!removed) {
 		/*
@@ -3799,12 +3800,13 @@ static int ref_update_reject_duplicates(struct ref_update **updates, int n,
 int transaction_commit(struct transaction *transaction,
 		       struct strbuf *err)
 {
-	int ret = 0, delnum = 0, i, need_repack = 0;
-	const char **delnames;
+	int ret = 0, i, need_repack = 0;
 	int n = transaction->nr;
 	struct packed_ref_cache *packed_ref_cache;
 	struct ref_update **updates = transaction->updates;
 	struct ref_dir *packed;
+	struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
+	struct string_list_item *ref_to_delete;
 
 	assert(err);
 
@@ -3816,9 +3818,6 @@ int transaction_commit(struct transaction *transaction,
 		return 0;
 	}
 
-	/* Allocate work space */
-	delnames = xmalloc(sizeof(*delnames) * n);
-
 	/* Copy, sort, and reject duplicate refs */
 	qsort(updates, n, sizeof(*updates), ref_update_compare);
 	if (ref_update_reject_duplicates(updates, n, err)) {
@@ -3910,7 +3909,8 @@ int transaction_commit(struct transaction *transaction,
 		}
 		try_remove_empty_parents((char *)update->refname);
 		if (!(update->flags & REF_ISPRUNING))
-			  delnames[delnum++] = xstrdup(update->lock->ref_name);
+			string_list_insert(&refs_to_delete,
+					   update->lock->ref_name);
 		unlock_ref(update->lock);
 		update->lock = NULL;
 	}
@@ -3927,7 +3927,7 @@ int transaction_commit(struct transaction *transaction,
 						   (update->have_old ?
 						    update->old_sha1 :
 						    NULL),
-						   NULL,
+						   &refs_to_delete,
 						   update->flags,
 						   &update->type);
 		if (!update->lock) {
@@ -3941,8 +3941,8 @@ int transaction_commit(struct transaction *transaction,
 	}
 
 	/* delete reflog for all deleted refs */
-	for (i = 0; i < delnum; i++)
-		unlink_or_warn(git_path("logs/%s", delnames[i]));
+	for_each_string_list_item(ref_to_delete, &refs_to_delete)
+		unlink_or_warn(git_path("logs/%s", ref_to_delete->string));
 
 	/* Lock all reflog files */
 	for (i = 0; i < n; i++) {
@@ -4049,7 +4049,7 @@ int transaction_commit(struct transaction *transaction,
 		}
 	}
 
-	if (repack_without_refs(delnames, delnum, err))
+	if (repack_without_refs(&refs_to_delete, err))
 		ret = TRANSACTION_GENERIC_ERROR;
 	clear_loose_ref_cache(&ref_cache);
 
@@ -4062,7 +4062,7 @@ cleanup:
 	for (i = 0; i < n; i++)
 		if (updates[i]->lock)
 			unlock_ref(updates[i]->lock);
-	free(delnames);
+	string_list_clear(&refs_to_delete, 0);
 	return ret;
 }
 
diff --git a/refs.h b/refs.h
index 9153e1d..d174380 100644
--- a/refs.h
+++ b/refs.h
@@ -163,7 +163,7 @@ extern void rollback_packed_refs(void);
  */
 int pack_refs(unsigned int flags);
 
-extern int repack_without_refs(const char **refnames, int n,
+extern int repack_without_refs(struct string_list *without,
 			       struct strbuf *err);
 
 extern int ref_exists(const char *);
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 05/16] refs.c: add transaction support for renaming a reflog

[Ronnie Sahlberg]

Add a new transaction function transaction_rename_reflog.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 refs.h |  8 ++++++++
 2 files changed, 79 insertions(+), 1 deletion(-)

diff --git a/refs.c b/refs.c
index e9e321e..8ca6add 100644
--- a/refs.c
+++ b/refs.c
@@ -35,6 +35,11 @@ static unsigned char refname_disposition[256] = {
  * just use the lock taken by the first update.
  */
 #define UPDATE_REFLOG_NOLOCK 0x0200
+/*
+ * This update is used to replace a new or existing reflog with new content
+ * held in update->new_reflog.
+ */
+#define REFLOG_REPLACE 0x0400
 
 /*
  * Try to read one refname component from the front of refname.
@@ -2821,6 +2826,37 @@ static int rename_ref_available(const char *oldname, const char *newname)
 static int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1,
 			  const char *logmsg);
 
+/*
+ * This is an optimized function to read the whole reflog as a blob
+ * into a strbuf. It is used during ref_rename so that we can use an
+ * efficient method to read the whole log and later write it back to a
+ * different file.
+ */
+static int copy_reflog_into_strbuf(const char *refname, struct strbuf *buf)
+{
+	struct stat st;
+	int fd;
+
+	if (lstat(git_path("logs/%s", refname), &st) == -1)
+		return 1;
+	if ((fd = open(git_path("logs/%s", refname), O_RDONLY)) == -1) {
+		error("failed to open reflog %s, %s",
+		      refname, strerror(errno));
+		return 1;
+	}
+	strbuf_init(buf, st.st_size);
+	strbuf_setlen(buf, st.st_size);
+	if (read_in_full(fd, buf->buf, st.st_size) != st.st_size) {
+		close(fd);
+		error("failed to read reflog %s, %s",
+		      refname, strerror(errno));
+		return 1;
+	}
+	close(fd);
+
+	return 0;
+}
+
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
 	unsigned char sha1[20], orig_sha1[20];
@@ -3561,6 +3597,7 @@ struct ref_update {
 	struct lock_file *reflog_lock;
 	char *committer;
 	struct ref_update *orig_update; /* For UPDATE_REFLOG_NOLOCK */
+	struct strbuf new_reflog;
 
 	const char refname[FLEX_ARRAY];
 };
@@ -3607,6 +3644,7 @@ void transaction_free(struct transaction *transaction)
 		return;
 
 	for (i = 0; i < transaction->nr; i++) {
+		strbuf_release(&transaction->updates[i]->new_reflog);
 		free(transaction->updates[i]->msg);
 		free(transaction->updates[i]->committer);
 		free(transaction->updates[i]);
@@ -3622,6 +3660,7 @@ static struct ref_update *add_update(struct transaction *transaction,
 	size_t len = strlen(refname);
 	struct ref_update *update = xcalloc(1, sizeof(*update) + len + 1);
 
+	strbuf_init(&update->new_reflog, 0);
 	strcpy((char *)update->refname, refname);
 	update->update_type = update_type;
 	ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
@@ -3681,6 +3720,27 @@ int transaction_update_reflog(struct transaction *transaction,
 	return 0;
 }
 
+int transaction_rename_reflog(struct transaction *transaction,
+			      const char *oldrefname,
+			      const char *newrefname,
+			      struct strbuf *err)
+{
+	struct ref_update *update;
+
+	if (transaction->state != TRANSACTION_OPEN)
+		die("BUG: transaction_replace_reflog called for transaction "
+		    "that is not open");
+
+	update = add_update(transaction, newrefname, UPDATE_LOG);
+	update->flags = REFLOG_REPLACE;
+	update->reflog_lock = xcalloc(1, sizeof(struct lock_file));
+	if (copy_reflog_into_strbuf(oldrefname, &update->new_reflog))
+		die("BUG: failed to read old reflog in "
+		    "transaction_rename_reflog");
+
+	return 0;
+}
+
 int transaction_update_ref(struct transaction *transaction,
 			   const char *refname,
 			   const unsigned char *new_sha1,
@@ -4012,7 +4072,7 @@ int transaction_commit(struct transaction *transaction,
 			continue;
 		if (update->reflog_fd == -1)
 			continue;
-		if (update->flags & REFLOG_TRUNCATE)
+		if (update->flags & (REFLOG_TRUNCATE|REFLOG_REPLACE))
 			if (lseek(update->reflog_fd, 0, SEEK_SET) < 0 ||
 				ftruncate(update->reflog_fd, 0)) {
 				error("Could not truncate reflog: %s. %s",
@@ -4030,6 +4090,16 @@ int transaction_commit(struct transaction *transaction,
 			rollback_lock_file(update->reflog_lock);
 			update->reflog_fd = -1;
 		}
+		if (update->flags & REFLOG_REPLACE)
+			if (write_in_full(update->reflog_fd,
+					  update->new_reflog.buf,
+					  update->new_reflog.len) !=
+			    update->new_reflog.len) {
+				error("Could write to reflog: %s. %s",
+				      update->refname, strerror(errno));
+				rollback_lock_file(update->reflog_lock);
+				update->reflog_fd = -1;
+			}
 	}
 
 	/* Commit all reflog files */
diff --git a/refs.h b/refs.h
index d174380..0ba078e 100644
--- a/refs.h
+++ b/refs.h
@@ -354,6 +354,14 @@ int transaction_update_reflog(struct transaction *transaction,
 			      struct strbuf *err);
 
 /*
+ * Rename a reflog.
+ */
+int transaction_rename_reflog(struct transaction *transaction,
+			      const char *oldrefname,
+			      const char *newrefname,
+			      struct strbuf *err);
+
+/*
  * Commit all of the changes that have been queued in transaction, as
  * atomically as possible.
  *
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 06/16] refs.c: update rename_ref to use a transaction

[Ronnie Sahlberg]

Change refs.c to use a single transaction to perform the rename.
Change the function to return 1 on failure instead of either -1 or 1.

These changes make the rename_ref operation atomic.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c            | 168 ++++++++++++++----------------------------------------
 t/t3200-branch.sh |   7 ---
 2 files changed, 43 insertions(+), 132 deletions(-)

diff --git a/refs.c b/refs.c
index 8ca6add..9a3c7fe 100644
--- a/refs.c
+++ b/refs.c
@@ -2757,60 +2757,6 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 	return 0;
 }
 
-/*
- * People using contrib's git-new-workdir have .git/logs/refs ->
- * /some/other/path/.git/logs/refs, and that may live on another device.
- *
- * IOW, to avoid cross device rename errors, the temporary renamed log must
- * live into logs/refs.
- */
-#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
-
-static int rename_tmp_log(const char *newrefname)
-{
-	int attempts_remaining = 4;
-
- retry:
-	switch (safe_create_leading_directories(git_path("logs/%s", newrefname))) {
-	case SCLD_OK:
-		break; /* success */
-	case SCLD_VANISHED:
-		if (--attempts_remaining > 0)
-			goto retry;
-		/* fall through */
-	default:
-		error("unable to create directory for %s", newrefname);
-		return -1;
-	}
-
-	if (rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
-		if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
-			/*
-			 * rename(a, b) when b is an existing
-			 * directory ought to result in ISDIR, but
-			 * Solaris 5.8 gives ENOTDIR.  Sheesh.
-			 */
-			if (remove_empty_directories(git_path("logs/%s", newrefname))) {
-				error("Directory not empty: logs/%s", newrefname);
-				return -1;
-			}
-			goto retry;
-		} else if (errno == ENOENT && --attempts_remaining > 0) {
-			/*
-			 * Maybe another process just deleted one of
-			 * the directories in the path to newrefname.
-			 * Try again from the beginning.
-			 */
-			goto retry;
-		} else {
-			error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
-				newrefname, strerror(errno));
-			return -1;
-		}
-	}
-	return 0;
-}
-
 static int rename_ref_available(const char *oldname, const char *newname)
 {
 	struct string_list skip = STRING_LIST_INIT_NODUP;
@@ -2859,91 +2805,63 @@ static int copy_reflog_into_strbuf(const char *refname, struct strbuf *buf)
 
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
-	unsigned char sha1[20], orig_sha1[20];
-	int flag = 0, logmoved = 0;
-	struct ref_lock *lock;
-	struct stat loginfo;
-	int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
+	unsigned char sha1[20];
+	int flag = 0;
+	int log;
+	struct transaction *transaction = NULL;
+	struct strbuf err = STRBUF_INIT;
 	const char *symref = NULL;
+	struct reflog_committer_info ci;
 
-	if (log && S_ISLNK(loginfo.st_mode))
-		return error("reflog for %s is a symlink", oldrefname);
+	memset(&ci, 0, sizeof(ci));
+	ci.committer_info = git_committer_info(0);
 
 	symref = resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING,
-				    orig_sha1, &flag);
-	if (flag & REF_ISSYMREF)
-		return error("refname %s is a symbolic ref, renaming it is not supported",
-			oldrefname);
-	if (!symref)
-		return error("refname %s not found", oldrefname);
-
-	if (!rename_ref_available(oldrefname, newrefname))
+				    sha1, &flag);
+	if (flag & REF_ISSYMREF) {
+		error("refname %s is a symbolic ref, renaming it is not "
+		      "supported", oldrefname);
 		return 1;
-
-	if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
-		return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
-			oldrefname, strerror(errno));
-
-	if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
-		error("unable to delete old %s", oldrefname);
-		goto rollback;
 	}
-
-	if (!read_ref_full(newrefname, RESOLVE_REF_READING, sha1, NULL) &&
-	    delete_ref(newrefname, sha1, REF_NODEREF)) {
-		if (errno==EISDIR) {
-			if (remove_empty_directories(git_path("%s", newrefname))) {
-				error("Directory not empty: %s", newrefname);
-				goto rollback;
-			}
-		} else {
-			error("unable to delete existing %s", newrefname);
-			goto rollback;
-		}
+	if (!symref) {
+		error("refname %s not found", oldrefname);
+		return 1;
 	}
 
-	if (log && rename_tmp_log(newrefname))
-		goto rollback;
+	if (!rename_ref_available(oldrefname, newrefname))
+		return 1;
 
-	logmoved = log;
+	log = reflog_exists(oldrefname);
 
-	lock = lock_ref_sha1_basic(newrefname, NULL, NULL, 0, NULL);
-	if (!lock) {
-		error("unable to lock %s for update", newrefname);
-		goto rollback;
-	}
-	lock->force_write = 1;
-	hashcpy(lock->old_sha1, orig_sha1);
-	if (write_ref_sha1(lock, orig_sha1, logmsg)) {
-		error("unable to write current sha1 into %s", newrefname);
-		goto rollback;
+	transaction = transaction_begin(&err);
+	if (!transaction)
+		goto fail;
+
+	if (strcmp(oldrefname, newrefname)) {
+		if (transaction_delete_ref(transaction, oldrefname, sha1,
+					   REF_NODEREF, 1, NULL, &err))
+			goto fail;
+		if (log && transaction_rename_reflog(transaction, oldrefname,
+						     newrefname, &err))
+			goto fail;
+		if (log && transaction_update_reflog(transaction, newrefname,
+				     sha1, sha1, &ci, logmsg,
+				     REFLOG_COMMITTER_INFO_IS_VALID, &err))
+			goto fail;
 	}
 
+	if (transaction_update_ref(transaction, newrefname, sha1,
+				   NULL, 0, 0, NULL, &err))
+		goto fail;
+	if (transaction_commit(transaction, &err))
+		goto fail;
+	transaction_free(transaction);
 	return 0;
 
- rollback:
-	lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, 0, NULL);
-	if (!lock) {
-		error("unable to lock %s for rollback", oldrefname);
-		goto rollbacklog;
-	}
-
-	lock->force_write = 1;
-	flag = log_all_ref_updates;
-	log_all_ref_updates = 0;
-	if (write_ref_sha1(lock, orig_sha1, NULL))
-		error("unable to write current sha1 into %s", oldrefname);
-	log_all_ref_updates = flag;
-
- rollbacklog:
-	if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
-		error("unable to restore logfile %s from %s: %s",
-			oldrefname, newrefname, strerror(errno));
-	if (!logmoved && log &&
-	    rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
-		error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
-			oldrefname, strerror(errno));
-
+ fail:
+	error("rename_ref failed: %s", err.buf);
+	strbuf_release(&err);
+	transaction_free(transaction);
 	return 1;
 }
 
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index 432921b..c6c53e4 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -302,13 +302,6 @@ test_expect_success 'renaming a symref is not allowed' '
 	test_path_is_missing .git/refs/heads/master3
 '
 
-test_expect_success SYMLINKS 'git branch -m u v should fail when the reflog for u is a symlink' '
-	git branch -l u &&
-	mv .git/logs/refs/heads/u real-u &&
-	ln -s real-u .git/logs/refs/heads/u &&
-	test_must_fail git branch -m u v
-'
-
 test_expect_success 'test tracking setup via --track' '
 	git config remote.local.url . &&
 	git config remote.local.fetch refs/heads/*:refs/remotes/local/* &&
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 07/16] refs.c: rollback the lockfile before we die() in repack_without_refs

[Ronnie Sahlberg]

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 refs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/refs.c b/refs.c
index 9a3c7fe..5a8f3da 100644
--- a/refs.c
+++ b/refs.c
@@ -2707,8 +2707,10 @@ int repack_without_refs(struct string_list *without, struct strbuf *err)
 	/* Remove any other accumulated cruft */
 	do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
 	for_each_string_list_item(ref_to_delete, &refs_to_delete) {
-		if (remove_entry(packed, ref_to_delete->string) == -1)
+		if (remove_entry(packed, ref_to_delete->string) == -1) {
+			rollback_packed_refs();
 			die("internal error");
+		}
 	}
 
 	/* Write what remains */
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 08/16] refs.c: move reflog updates into its own function

[Ronnie Sahlberg]

write_ref_sha1 tries to update the reflog while updating the ref.
Move these reflog changes out into its own function so that we can do the
same thing if we write a sha1 ref differently, for example by writing a ref
to the packed refs file instead.

No functional changes intended. We only move some code out into a separate
function.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 60 +++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 35 insertions(+), 25 deletions(-)

diff --git a/refs.c b/refs.c
index 5a8f3da..7f4b4cb 100644
--- a/refs.c
+++ b/refs.c
@@ -3028,6 +3028,40 @@ int is_branch(const char *refname)
 	return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 }
 
+static int write_sha1_update_reflog(struct ref_lock *lock,
+	const unsigned char *sha1, const char *logmsg)
+{
+	if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
+	    (strcmp(lock->ref_name, lock->orig_ref_name) &&
+	     log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
+		unlock_ref(lock);
+		return -1;
+	}
+	if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
+		/*
+		 * Special hack: If a branch is updated directly and HEAD
+		 * points to it (may happen on the remote side of a push
+		 * for example) then logically the HEAD reflog should be
+		 * updated too.
+		 * A generic solution implies reverse symref information,
+		 * but finding all symrefs pointing to the given branch
+		 * would be rather costly for this rare event (the direct
+		 * update of a branch) to be worth it.  So let's cheat and
+		 * check with HEAD only which should cover 99% of all usage
+		 * scenarios (even 100% of the default ones).
+		 */
+		unsigned char head_sha1[20];
+		int head_flag;
+		const char *head_ref;
+		head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
+					      head_sha1, &head_flag);
+		if (head_ref && (head_flag & REF_ISSYMREF) &&
+		    !strcmp(head_ref, lock->ref_name))
+			log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
+	}
+	return 0;
+}
+
 /*
  * Write sha1 into the ref specified by the lock. Make sure that errno
  * is sane on error.
@@ -3071,34 +3105,10 @@ static int write_ref_sha1(struct ref_lock *lock,
 		return -1;
 	}
 	clear_loose_ref_cache(&ref_cache);
-	if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
-	    (strcmp(lock->ref_name, lock->orig_ref_name) &&
-	     log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
+	if (write_sha1_update_reflog(lock, sha1, logmsg)) {
 		unlock_ref(lock);
 		return -1;
 	}
-	if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
-		/*
-		 * Special hack: If a branch is updated directly and HEAD
-		 * points to it (may happen on the remote side of a push
-		 * for example) then logically the HEAD reflog should be
-		 * updated too.
-		 * A generic solution implies reverse symref information,
-		 * but finding all symrefs pointing to the given branch
-		 * would be rather costly for this rare event (the direct
-		 * update of a branch) to be worth it.  So let's cheat and
-		 * check with HEAD only which should cover 99% of all usage
-		 * scenarios (even 100% of the default ones).
-		 */
-		unsigned char head_sha1[20];
-		int head_flag;
-		const char *head_ref;
-		head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
-					      head_sha1, &head_flag);
-		if (head_ref && (head_flag & REF_ISSYMREF) &&
-		    !strcmp(head_ref, lock->ref_name))
-			log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
-	}
 	if (commit_ref(lock)) {
 		error("Couldn't set %s", lock->ref_name);
 		unlock_ref(lock);
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 09/16] refs.c: write updates to packed refs when a transaction has more than one ref

[Ronnie Sahlberg]

When we are updating more than one single ref, i.e. not a commit, then
write the updated refs directly to the packed refs file instead of writing
them as loose refs.

Change clone to use a transaction instead of using the packed refs API.
This changes the behavior of clone slightly. Previously clone would always
clone all refs into a packed refs file. With this change clone will only
clone into packed refs iff there are two or more refs being cloned.
If the repository we are cloning from only contains exactly one single ref
then clone will now store this as a loose ref. The benefit here is that
we no longer need to export a bunch of API functions to clone to access
packed refs directly. Clone can now just use a normal transaction and all
the packed refs goodness will happen automatically.

Update the t5516 test to cope with the fact that clone now only uses
packed refs if there are more than one ref being cloned.

We still use loose refs for single ref transactions, such as are used
by 'git commit' and friends. The reason for this is that if you have very
many refs then having to re-write the whole packed refs file for every
common operation like commit would have a performance impact.
That said, with these changes it should now be fairly straightforward to
add support to optionally start using packed refs for ALL updates
which could solve existing issues with name clashes in case insensitive
filesystems.

This change also means that multi-ref updates will now appear as a single
atomic change to any external observers instead of a sequence of discreete
changes.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/clone.c       | 16 ++++++---
 refs.c                | 89 ++++++++++++++++++++++++++++++++++-----------------
 t/t5516-fetch-push.sh |  2 +-
 3 files changed, 72 insertions(+), 35 deletions(-)

diff --git a/builtin/clone.c b/builtin/clone.c
index 316c75d..bb2c058 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -498,17 +498,25 @@ static struct ref *wanted_peer_refs(const struct ref *refs,
 static void write_remote_refs(const struct ref *local_refs)
 {
 	const struct ref *r;
+	struct transaction *transaction;
+	struct strbuf err = STRBUF_INIT;
 
-	lock_packed_refs(LOCK_DIE_ON_ERROR);
+	transaction = transaction_begin(&err);
+	if (!transaction)
+		die("%s", err.buf);
 
 	for (r = local_refs; r; r = r->next) {
 		if (!r->peer_ref)
 			continue;
-		add_packed_ref(r->peer_ref->name, r->old_sha1);
+		if (transaction_update_ref(transaction, r->peer_ref->name,
+					   r->old_sha1, NULL, 0, 0, NULL,
+					   &err))
+			die("%s", err.buf);
 	}
 
-	if (commit_packed_refs())
-		die_errno("unable to overwrite old ref-pack file");
+	if (transaction_commit(transaction, &err))
+		die("%s", err.buf);
+	transaction_free(transaction);
 }
 
 static void write_followtags(const struct ref *refs, const char *msg)
diff --git a/refs.c b/refs.c
index 7f4b4cb..c1db86f 100644
--- a/refs.c
+++ b/refs.c
@@ -2673,36 +2673,15 @@ int repack_without_refs(struct string_list *without, struct strbuf *err)
 	struct ref_dir *packed;
 	struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
 	struct string_list_item *ref_to_delete;
-	int count, ret, removed = 0;
+	int ret;
 
 	assert(err);
 
-	/* Look for a packed ref */
-	count = 0;
-	for_each_string_list_item(ref_to_delete, without)
-		if (get_packed_ref(ref_to_delete->string))
-			count++;
-
-	/* No refname exists in packed refs */
-	if (!count) {
-		rollback_packed_refs();
-		return 0;
-	}
-
 	packed = get_packed_refs(&ref_cache);
 
 	/* Remove refnames from the cache */
 	for_each_string_list_item(ref_to_delete, without)
-		if (remove_entry(packed, ref_to_delete->string) != -1)
-			removed = 1;
-	if (!removed) {
-		/*
-		 * All packed entries disappeared while we were
-		 * acquiring the lock.
-		 */
-		rollback_packed_refs();
-		return 0;
-	}
+		remove_entry(packed, ref_to_delete->string);
 
 	/* Remove any other accumulated cruft */
 	do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
@@ -3791,6 +3770,7 @@ int transaction_commit(struct transaction *transaction,
 		       struct strbuf *err)
 {
 	int ret = 0, i, need_repack = 0;
+	int num_updates = 0;
 	int n = transaction->nr;
 	struct packed_ref_cache *packed_ref_cache;
 	struct ref_update **updates = transaction->updates;
@@ -3824,14 +3804,30 @@ int transaction_commit(struct transaction *transaction,
 		goto cleanup;
 	}
 
-	/* any loose refs are to be deleted are first copied to packed refs */
+	/* count how many refs we are updating (not deleting) */
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+
+		if (update->update_type != UPDATE_SHA1)
+			continue;
+		if (is_null_sha1(update->new_sha1))
+			continue;
+
+		num_updates++;
+	}
+
+	/*
+	 * Always copy loose refs that are to be deleted to the packed refs.
+	 * If we are updating multiple refs then copy all refs to the packed
+	 * refs file.
+	 */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
 		unsigned char sha1[20];
 
 		if (update->update_type != UPDATE_SHA1)
 			continue;
-		if (!is_null_sha1(update->new_sha1))
+		if (num_updates < 2 && !is_null_sha1(update->new_sha1))
 			continue;
 		if (get_packed_ref(update->refname))
 			continue;
@@ -3843,7 +3839,7 @@ int transaction_commit(struct transaction *transaction,
 		need_repack = 1;
 	}
 	if (need_repack) {
-		packed = get_packed_refs(&ref_cache);;
+		packed = get_packed_refs(&ref_cache);
 		sort_ref_dir(packed);
 		if (commit_packed_refs()){
 			strbuf_addf(err, "unable to overwrite old ref-pack "
@@ -3860,13 +3856,15 @@ int transaction_commit(struct transaction *transaction,
 			goto cleanup;
 		}
 	}
+	need_repack = 0;
 
 	/*
 	 * At this stage any refs that are to be deleted have been moved to the
-	 * packed refs file anf the packed refs file is deleted. We can now
+	 * packed refs file and the packed refs file is committed. We can now
 	 * safely delete these loose refs.
+	 * If we are updating multiple refs then those will also be in the
+	 * packed refs file so we can delete those too.
 	 */
-
 	/* Unlink any loose refs scheduled for deletion */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
@@ -3905,7 +3903,10 @@ int transaction_commit(struct transaction *transaction,
 		update->lock = NULL;
 	}
 
-	/* Acquire all ref locks for updates while verifying old values */
+	/*
+	 * Acquire all ref locks for updates while verifying old values.
+	 * If we are multi-updating then update them in packed refs.
+	 */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
 
@@ -3928,6 +3929,30 @@ int transaction_commit(struct transaction *transaction,
 				    update->refname);
 			goto cleanup;
 		}
+		if (num_updates < 2)
+			continue;
+
+		if (delete_ref_loose(update->lock, update->type, err)) {
+			ret = -1;
+			goto cleanup;
+		}
+		if (write_sha1_update_reflog(update->lock, update->new_sha1,
+					     update->msg)) {
+			if (err)
+				strbuf_addf(err, "Failed to update log '%s'.",
+					    update->refname);
+			ret = -1;
+			goto cleanup;
+		}
+		unlock_ref(update->lock);
+		update->lock = NULL;
+
+		packed = get_packed_refs(&ref_cache);
+		remove_entry(packed, update->refname);
+		add_packed_ref(update->refname, update->new_sha1);
+		need_repack = 1;
+
+		try_remove_empty_parents((char *)update->refname);
 	}
 
 	/* delete reflog for all deleted refs */
@@ -3976,7 +4001,7 @@ int transaction_commit(struct transaction *transaction,
 
 		if (update->update_type != UPDATE_SHA1)
 			continue;
-		if (!is_null_sha1(update->new_sha1)) {
+		if (update->lock && !is_null_sha1(update->new_sha1)) {
 			if (write_ref_sha1(update->lock, update->new_sha1,
 					   update->msg)) {
 				update->lock = NULL; /* freed by write_ref_sha1 */
@@ -4049,6 +4074,10 @@ int transaction_commit(struct transaction *transaction,
 		}
 	}
 
+	if (need_repack) {
+		packed = get_packed_refs(&ref_cache);
+		sort_ref_dir(packed);
+	}
 	if (repack_without_refs(&refs_to_delete, err))
 		ret = TRANSACTION_GENERIC_ERROR;
 	clear_loose_ref_cache(&ref_cache);
diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
index 7c8a769..03375a9 100755
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@ -592,7 +592,7 @@ test_expect_success 'push updates up-to-date local refs' '
 
 test_expect_success 'push preserves up-to-date packed refs' '
 
-	mk_test testrepo heads/master &&
+	mk_test testrepo heads/master heads/foo heads/bar &&
 	mk_child testrepo child &&
 	(
 		cd child &&
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 10/16] remote.c: use a transaction for deleting refs

[Ronnie Sahlberg]

Transactions now use packed refs when deleting multiple refs so there is no
need to do it manually from remote.c any more.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/remote.c | 80 ++++++++++++++++++++++++++++----------------------------
 1 file changed, 40 insertions(+), 40 deletions(-)

diff --git a/builtin/remote.c b/builtin/remote.c
index 6806251..42702d7 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -750,30 +750,27 @@ static int mv(int argc, const char **argv)
 
 static int remove_branches(struct string_list *branches)
 {
-	struct strbuf err = STRBUF_INIT;
 	int i, result = 0;
+	struct transaction *transaction;
+	struct strbuf err = STRBUF_INIT;
 
-	if (lock_packed_refs(0)) {
-		struct strbuf err = STRBUF_INIT;
-
-		unable_to_lock_message(git_path("packed-refs"), errno, &err);
-		error("%s", err.buf);
-		strbuf_release(&err);
-		return -1;
-	}
+	transaction = transaction_begin(&err);
+	if (!transaction)
+		die("%s", err.buf);
 
-	if (repack_without_refs(branches, &err))
+	for (i = 0; i < branches->nr; i++)
+		if (transaction_delete_ref(transaction,
+					   branches->items[i].string, NULL,
+					   0, 0, "remote-branches", &err)) {
+			result |= error("%s", err.buf);
+			goto cleanup;
+		}
+	if (transaction_commit(transaction, &err))
 		result |= error("%s", err.buf);
-	strbuf_release(&err);
-
-	for (i = 0; i < branches->nr; i++) {
-		struct string_list_item *item = branches->items + i;
-		const char *refname = item->string;
-
-		if (delete_ref(refname, NULL, 0))
-			result |= error(_("Could not remove branch %s"), refname);
-	}
 
+ cleanup:
+	strbuf_release(&err);
+	transaction_free(transaction);
 	return result;
 }
 
@@ -1325,42 +1322,38 @@ static int prune_remote(const char *remote, int dry_run)
 	const char *dangling_msg = dry_run
 		? _(" %s will become dangling!")
 		: _(" %s has become dangling!");
+	struct transaction *transaction = NULL;
+	struct strbuf err = STRBUF_INIT;
 
 	memset(&states, 0, sizeof(states));
 	get_remote_ref_states(remote, &states, GET_REF_STATES);
 
-	for (i = 0; i < states.stale.nr; i++) {
-		string_list_insert(&delete_refs_list,
-				   states.stale.items[i].util);
-	}
-
 	if (states.stale.nr) {
 		printf_ln(_("Pruning %s"), remote);
 		printf_ln(_("URL: %s"),
 		       states.remote->url_nr
 		       ? states.remote->url[0]
 		       : _("(no URL)"));
-
-		if (!dry_run) {
-			struct strbuf err = STRBUF_INIT;
-
-			if (lock_packed_refs(0)) {
-				unable_to_lock_message(git_path("packed-refs"),
-						       errno, &err);
-				result |= error("%s", err.buf);
-			} else
-				if (repack_without_refs(&delete_refs_list,
-							&err))
-					result |= error("%s", err.buf);
-			strbuf_release(&err);
-		}
 	}
 
+	if (!dry_run) {
+		transaction = transaction_begin(&err);
+		if (!transaction)
+			die("%s", err.buf);
+	}
 	for (i = 0; i < states.stale.nr; i++) {
 		const char *refname = states.stale.items[i].util;
 
-		if (!dry_run)
-			result |= delete_ref(refname, NULL, 0);
+		string_list_insert(&delete_refs_list, refname);
+
+		if (!dry_run) {
+			if (transaction_delete_ref(transaction,
+					   refname, NULL,
+					   0, 0, "remote-branches", &err)) {
+				result |= error("%s", err.buf);
+				goto cleanup;
+			}
+		}
 
 		if (dry_run)
 			printf_ln(_(" * [would prune] %s"),
@@ -1370,6 +1363,13 @@ static int prune_remote(const char *remote, int dry_run)
 			       abbrev_ref(refname, "refs/remotes/"));
 	}
 
+	if (!dry_run)
+		if (transaction_commit(transaction, &err))
+			result |= error("%s", err.buf);
+
+ cleanup:
+	strbuf_release(&err);
+	transaction_free(transaction);
 	warn_dangling_symrefs(stdout, dangling_msg, &delete_refs_list);
 	string_list_clear(&delete_refs_list, 0);
 
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 11/16] refs.c: make repack_without_refs static

[Ronnie Sahlberg]

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 2 +-
 refs.h | 3 ---
 2 files changed, 1 insertion(+), 4 deletions(-)

diff --git a/refs.c b/refs.c
index c1db86f..2c6b0f6 100644
--- a/refs.c
+++ b/refs.c
@@ -2668,7 +2668,7 @@ static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
 /*
  * Must be called with packed refs already locked (and sorted)
  */
-int repack_without_refs(struct string_list *without, struct strbuf *err)
+static int repack_without_refs(struct string_list *without, struct strbuf *err)
 {
 	struct ref_dir *packed;
 	struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
diff --git a/refs.h b/refs.h
index 0ba078e..ce290b1 100644
--- a/refs.h
+++ b/refs.h
@@ -163,9 +163,6 @@ extern void rollback_packed_refs(void);
  */
 int pack_refs(unsigned int flags);
 
-extern int repack_without_refs(struct string_list *without,
-			       struct strbuf *err);
-
 extern int ref_exists(const char *);
 
 extern int is_branch(const char *refname);
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 12/16] refs.c: make the *_packed_refs functions static

[Ronnie Sahlberg]

We no longer need to expose the lock/add/commit/rollback functions
for packed refs anymore so make them static and remove them from the
public api.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c |  8 ++++----
 refs.h | 30 ------------------------------
 2 files changed, 4 insertions(+), 34 deletions(-)

diff --git a/refs.c b/refs.c
index 2c6b0f6..eee9a14 100644
--- a/refs.c
+++ b/refs.c
@@ -1229,7 +1229,7 @@ static struct ref_dir *get_packed_refs(struct ref_cache *refs)
 	return get_packed_ref_dir(get_packed_ref_cache(refs));
 }
 
-void add_packed_ref(const char *refname, const unsigned char *sha1)
+static void add_packed_ref(const char *refname, const unsigned char *sha1)
 {
 	struct packed_ref_cache *packed_ref_cache =
 		get_packed_ref_cache(&ref_cache);
@@ -2398,7 +2398,7 @@ static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
 }
 
 /* This should return a meaningful errno on failure */
-int lock_packed_refs(int flags)
+static int lock_packed_refs(int flags)
 {
 	struct packed_ref_cache *packed_ref_cache;
 
@@ -2421,7 +2421,7 @@ int lock_packed_refs(int flags)
  * Commit the packed refs changes.
  * On error we must make sure that errno contains a meaningful value.
  */
-int commit_packed_refs(void)
+static int commit_packed_refs(void)
 {
 	struct packed_ref_cache *packed_ref_cache =
 		get_packed_ref_cache(&ref_cache);
@@ -2450,7 +2450,7 @@ int commit_packed_refs(void)
 	return error;
 }
 
-void rollback_packed_refs(void)
+static void rollback_packed_refs(void)
 {
 	struct packed_ref_cache *packed_ref_cache =
 		get_packed_ref_cache(&ref_cache);
diff --git a/refs.h b/refs.h
index ce290b1..70a2819 100644
--- a/refs.h
+++ b/refs.h
@@ -120,36 +120,6 @@ extern void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refn
 extern void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames);
 
 /*
- * Lock the packed-refs file for writing.  Flags is passed to
- * hold_lock_file_for_update().  Return 0 on success.
- * Errno is set to something meaningful on error.
- */
-extern int lock_packed_refs(int flags);
-
-/*
- * Add a reference to the in-memory packed reference cache.  This may
- * only be called while the packed-refs file is locked (see
- * lock_packed_refs()).  To actually write the packed-refs file, call
- * commit_packed_refs().
- */
-extern void add_packed_ref(const char *refname, const unsigned char *sha1);
-
-/*
- * Write the current version of the packed refs cache from memory to
- * disk.  The packed-refs file must already be locked for writing (see
- * lock_packed_refs()).  Return zero on success.
- * Sets errno to something meaningful on error.
- */
-extern int commit_packed_refs(void);
-
-/*
- * Rollback the lockfile for the packed-refs file, and discard the
- * in-memory packed reference cache.  (The packed-refs file will be
- * read anew if it is needed again after this function is called.)
- */
-extern void rollback_packed_refs(void);
-
-/*
  * Flags for controlling behaviour of pack_refs()
  * PACK_REFS_PRUNE: Prune loose refs after packing
  * PACK_REFS_ALL:   Pack _all_ refs, not just tags and already packed refs
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 13/16] refs.c: replace the onerr argument in update_ref with a strbuf err

[Ronnie Sahlberg]

Get rid of the action_on_err enum and replace the action argument to
update_ref with a strbuf *err for error reporting.

Update all callers to the new api including two callers in transport*.c
which used the literal 0 instead of an enum.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/checkout.c   |  7 +++++--
 builtin/clone.c      | 20 ++++++++++++--------
 builtin/merge.c      | 20 +++++++++++++-------
 builtin/notes.c      | 24 ++++++++++++++----------
 builtin/reset.c      | 12 ++++++++----
 builtin/update-ref.c |  7 +++++--
 notes-cache.c        |  2 +-
 notes-utils.c        |  5 +++--
 refs.c               | 14 +++-----------
 refs.h               | 10 ++--------
 transport-helper.c   |  7 ++++++-
 transport.c          |  9 ++++++---
 12 files changed, 78 insertions(+), 59 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 8550b6d..60a68f7 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -584,6 +584,8 @@ static void update_refs_for_switch(const struct checkout_opts *opts,
 {
 	struct strbuf msg = STRBUF_INIT;
 	const char *old_desc, *reflog_msg;
+	struct strbuf err = STRBUF_INIT;
+
 	if (opts->new_branch) {
 		if (opts->new_orphan_branch) {
 			if (opts->new_branch_log && !log_all_ref_updates) {
@@ -621,8 +623,9 @@ static void update_refs_for_switch(const struct checkout_opts *opts,
 	if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 		/* Nothing to do. */
 	} else if (opts->force_detach || !new->path) {	/* No longer on any branch. */
-		update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
-			   REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
+		if (update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
+			       REF_NODEREF, &err))
+			die("%s", err.buf);
 		if (!opts->quiet) {
 			if (old->path && advice_detached_head)
 				detach_advice(new->name);
diff --git a/builtin/clone.c b/builtin/clone.c
index bb2c058..5577b5b 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -522,6 +522,7 @@ static void write_remote_refs(const struct ref *local_refs)
 static void write_followtags(const struct ref *refs, const char *msg)
 {
 	const struct ref *ref;
+	struct strbuf err = STRBUF_INIT;
 	for (ref = refs; ref; ref = ref->next) {
 		if (!starts_with(ref->name, "refs/tags/"))
 			continue;
@@ -529,8 +530,9 @@ static void write_followtags(const struct ref *refs, const char *msg)
 			continue;
 		if (!has_sha1_file(ref->old_sha1))
 			continue;
-		update_ref(msg, ref->name, ref->old_sha1,
-			   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+		if (update_ref(msg, ref->name, ref->old_sha1,
+			       NULL, 0, &err))
+			die("%s", err.buf);
 	}
 }
 
@@ -593,28 +595,30 @@ static void update_remote_refs(const struct ref *refs,
 static void update_head(const struct ref *our, const struct ref *remote,
 			const char *msg)
 {
+	struct strbuf err = STRBUF_INIT;
 	const char *head;
 	if (our && skip_prefix(our->name, "refs/heads/", &head)) {
 		/* Local default branch link */
 		create_symref("HEAD", our->name, NULL);
 		if (!option_bare) {
-			update_ref(msg, "HEAD", our->old_sha1, NULL, 0,
-				   UPDATE_REFS_DIE_ON_ERR);
+			update_ref(msg, "HEAD", our->old_sha1, NULL, 0, &err);
 			install_branch_config(0, head, option_origin, our->name);
 		}
 	} else if (our) {
 		struct commit *c = lookup_commit_reference(our->old_sha1);
 		/* --branch specifies a non-branch (i.e. tags), detach HEAD */
-		update_ref(msg, "HEAD", c->object.sha1,
-			   NULL, REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
+		if (update_ref(msg, "HEAD", c->object.sha1,
+			       NULL, REF_NODEREF, &err))
+			die("%s", err.buf);
 	} else if (remote) {
 		/*
 		 * We know remote HEAD points to a non-branch, or
 		 * HEAD points to a branch but we don't know which one.
 		 * Detach HEAD in all these cases.
 		 */
-		update_ref(msg, "HEAD", remote->old_sha1,
-			   NULL, REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
+	  if (update_ref(msg, "HEAD", remote->old_sha1,
+			 NULL, REF_NODEREF, &err))
+		die("%s", err.buf);
 	}
 }
 
diff --git a/builtin/merge.c b/builtin/merge.c
index bebbe5b..a787b6a 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -396,9 +396,11 @@ static void finish(struct commit *head_commit,
 			printf(_("No merge message -- not updating HEAD\n"));
 		else {
 			const char *argv_gc_auto[] = { "gc", "--auto", NULL };
-			update_ref(reflog_message.buf, "HEAD",
-				new_head, head, 0,
-				UPDATE_REFS_DIE_ON_ERR);
+			struct strbuf err = STRBUF_INIT;
+			if (update_ref(reflog_message.buf, "HEAD",
+				       new_head, head, 0,
+				       &err))
+				die("%s", err.buf);
 			/*
 			 * We ignore errors in 'gc --auto', since the
 			 * user should see them.
@@ -1086,6 +1088,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	unsigned char head_sha1[20];
 	struct commit *head_commit;
 	struct strbuf buf = STRBUF_INIT;
+	struct strbuf err = STRBUF_INIT;
 	const char *head_arg;
 	int flag, i, ret = 0, head_subsumed;
 	int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
@@ -1214,8 +1217,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		if (!remote_head)
 			die(_("%s - not something we can merge"), argv[0]);
 		read_empty(remote_head->object.sha1, 0);
-		update_ref("initial pull", "HEAD", remote_head->object.sha1,
-			   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+		if (update_ref("initial pull", "HEAD", remote_head->object.sha1,
+			       NULL, 0, &err))
+			die("%s", err.buf);
 		goto done;
 	} else {
 		struct strbuf merge_names = STRBUF_INIT;
@@ -1328,8 +1332,10 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		free(list);
 	}
 
-	update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
-		   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+	if (update_ref("updating ORIG_HEAD", "ORIG_HEAD",
+		       head_commit->object.sha1,
+		       NULL, 0, &err))
+		die("%s", err.buf);
 
 	if (remoteheads && !common)
 		; /* No common ancestors found. We need a real merge. */
diff --git a/builtin/notes.c b/builtin/notes.c
index 68b6cd8..b9fec39 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -674,6 +674,7 @@ static int merge_abort(struct notes_merge_options *o)
 static int merge_commit(struct notes_merge_options *o)
 {
 	struct strbuf msg = STRBUF_INIT;
+	struct strbuf err = STRBUF_INIT;
 	unsigned char sha1[20], parent_sha1[20];
 	struct notes_tree *t;
 	struct commit *partial;
@@ -714,10 +715,10 @@ static int merge_commit(struct notes_merge_options *o)
 	format_commit_message(partial, "%s", &msg, &pretty_ctx);
 	strbuf_trim(&msg);
 	strbuf_insert(&msg, 0, "notes: ", 7);
-	update_ref(msg.buf, o->local_ref, sha1,
-		   is_null_sha1(parent_sha1) ? NULL : parent_sha1,
-		   0, UPDATE_REFS_DIE_ON_ERR);
-
+	if (update_ref(msg.buf, o->local_ref, sha1,
+		       is_null_sha1(parent_sha1) ? NULL : parent_sha1,
+		       0, &err))
+		die("%s", err.buf);
 	free_notes(t);
 	strbuf_release(&msg);
 	ret = merge_abort(o);
@@ -728,6 +729,7 @@ static int merge_commit(struct notes_merge_options *o)
 static int merge(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf remote_ref = STRBUF_INIT, msg = STRBUF_INIT;
+	struct strbuf err = STRBUF_INIT;
 	unsigned char result_sha1[20];
 	struct notes_tree *t;
 	struct notes_merge_options o;
@@ -808,14 +810,16 @@ static int merge(int argc, const char **argv, const char *prefix)
 
 	result = notes_merge(&o, t, result_sha1);
 
-	if (result >= 0) /* Merge resulted (trivially) in result_sha1 */
+	if (result >= 0) {/* Merge resulted (trivially) in result_sha1 */
 		/* Update default notes ref with new commit */
-		update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
-			   0, UPDATE_REFS_DIE_ON_ERR);
-	else { /* Merge has unresolved conflicts */
+		if (update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
+			       0, &err))
+			die("%s", err.buf);
+	} else { /* Merge has unresolved conflicts */
 		/* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
-		update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
-			   0, UPDATE_REFS_DIE_ON_ERR);
+		if (update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
+			       0, &err))
+			die("%s", err.buf);
 		/* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
 		if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
 			die("Failed to store link to current notes ref (%s)",
diff --git a/builtin/reset.c b/builtin/reset.c
index 4c08ddc..8ebf4ca 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -245,6 +245,7 @@ static int reset_refs(const char *rev, const unsigned char *sha1)
 {
 	int update_ref_status;
 	struct strbuf msg = STRBUF_INIT;
+	struct strbuf err = STRBUF_INIT;
 	unsigned char *orig = NULL, sha1_orig[20],
 		*old_orig = NULL, sha1_old_orig[20];
 
@@ -253,13 +254,16 @@ static int reset_refs(const char *rev, const unsigned char *sha1)
 	if (!get_sha1("HEAD", sha1_orig)) {
 		orig = sha1_orig;
 		set_reflog_message(&msg, "updating ORIG_HEAD", NULL);
-		update_ref(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
-			   UPDATE_REFS_MSG_ON_ERR);
+		if (update_ref(msg.buf, "ORIG_HEAD", orig, old_orig, 0, &err))
+			error("%s", err.buf);
+		strbuf_release(&err);
 	} else if (old_orig)
 		delete_ref("ORIG_HEAD", old_orig, 0);
 	set_reflog_message(&msg, "updating HEAD", rev);
-	update_ref_status = update_ref(msg.buf, "HEAD", sha1, orig, 0,
-				       UPDATE_REFS_MSG_ON_ERR);
+	update_ref_status = update_ref(msg.buf, "HEAD", sha1, orig, 0, &err);
+	if (update_ref_status)
+		error("%s", err.buf);
+	strbuf_release(&err);
 	strbuf_release(&msg);
 	return update_ref_status;
 }
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index af08dd9..f650647 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -358,6 +358,7 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 	const char *refname, *oldval;
 	unsigned char sha1[20], oldsha1[20];
 	int delete = 0, no_deref = 0, read_stdin = 0, end_null = 0, flags = 0;
+	struct strbuf err = STRBUF_INIT;
 	struct option options[] = {
 		OPT_STRING( 'm', NULL, &msg, N_("reason"), N_("reason of the update")),
 		OPT_BOOL('d', NULL, &delete, N_("delete the reference")),
@@ -421,6 +422,8 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 	if (delete)
 		return delete_ref(refname, oldval ? oldsha1 : NULL, flags);
 	else
-		return update_ref(msg, refname, sha1, oldval ? oldsha1 : NULL,
-				  flags, UPDATE_REFS_DIE_ON_ERR);
+		if (update_ref(msg, refname, sha1, oldval ? oldsha1 : NULL,
+			       flags, &err))
+			die("%s", err.buf);
+	return 0;
 }
diff --git a/notes-cache.c b/notes-cache.c
index c4e9bb7..386e6d6 100644
--- a/notes-cache.c
+++ b/notes-cache.c
@@ -60,7 +60,7 @@ int notes_cache_write(struct notes_cache *c)
 			commit_sha1, NULL, NULL) < 0)
 		return -1;
 	if (update_ref("update notes cache", c->tree.ref, commit_sha1, NULL,
-		       0, UPDATE_REFS_QUIET_ON_ERR) < 0)
+		       0, NULL) < 0)
 		return -1;
 
 	return 0;
diff --git a/notes-utils.c b/notes-utils.c
index b64dc1b..bcfe61e 100644
--- a/notes-utils.c
+++ b/notes-utils.c
@@ -34,6 +34,7 @@ void commit_notes(struct notes_tree *t, const char *msg)
 {
 	struct strbuf buf = STRBUF_INIT;
 	unsigned char commit_sha1[20];
+	struct strbuf err = STRBUF_INIT;
 
 	if (!t)
 		t = &default_notes_tree;
@@ -49,8 +50,8 @@ void commit_notes(struct notes_tree *t, const char *msg)
 
 	create_notes_commit(t, NULL, buf.buf, buf.len, commit_sha1);
 	strbuf_insert(&buf, 0, "notes: ", 7); /* commit message starts at index 7 */
-	update_ref(buf.buf, t->ref, commit_sha1, NULL, 0,
-		   UPDATE_REFS_DIE_ON_ERR);
+	if (update_ref(buf.buf, t->ref, commit_sha1, NULL, 0, &err))
+		die("%s", err.buf);
 
 	strbuf_release(&buf);
 }
diff --git a/refs.c b/refs.c
index eee9a14..b59e2b8 100644
--- a/refs.c
+++ b/refs.c
@@ -3707,7 +3707,7 @@ int transaction_delete_ref(struct transaction *transaction,
 
 int update_ref(const char *action, const char *refname,
 	       const unsigned char *sha1, const unsigned char *oldval,
-	       int flags, enum action_on_err onerr)
+	       int flags, struct strbuf *e)
 {
 	struct transaction *t;
 	struct strbuf err = STRBUF_INIT;
@@ -3720,16 +3720,8 @@ int update_ref(const char *action, const char *refname,
 		const char *str = "update_ref failed for ref '%s': %s";
 
 		transaction_free(t);
-		switch (onerr) {
-		case UPDATE_REFS_MSG_ON_ERR:
-			error(str, refname, err.buf);
-			break;
-		case UPDATE_REFS_DIE_ON_ERR:
-			die(str, refname, err.buf);
-			break;
-		case UPDATE_REFS_QUIET_ON_ERR:
-			break;
-		}
+		if (e)
+			strbuf_addf(e, str, refname, err.buf);
 		strbuf_release(&err);
 		return 1;
 	}
diff --git a/refs.h b/refs.h
index 70a2819..b5ba685 100644
--- a/refs.h
+++ b/refs.h
@@ -212,12 +212,6 @@ extern int rename_ref(const char *oldref, const char *newref, const char *logmsg
  */
 extern int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1);
 
-enum action_on_err {
-	UPDATE_REFS_MSG_ON_ERR,
-	UPDATE_REFS_DIE_ON_ERR,
-	UPDATE_REFS_QUIET_ON_ERR
-};
-
 /*
  * Begin a reference transaction.  The reference transaction must
  * be freed by calling transaction_free().
@@ -348,8 +342,8 @@ void transaction_free(struct transaction *transaction);
 
 /** Lock a ref and then write its file */
 int update_ref(const char *action, const char *refname,
-		const unsigned char *sha1, const unsigned char *oldval,
-		int flags, enum action_on_err onerr);
+	       const unsigned char *sha1, const unsigned char *oldval,
+	       int flags, struct strbuf *err);
 
 extern int parse_hide_refs_config(const char *var, const char *value, const char *);
 extern int ref_is_hidden(const char *);
diff --git a/transport-helper.c b/transport-helper.c
index 6cd9dd1..ed72ecc 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -729,6 +729,7 @@ static int push_update_refs_status(struct helper_data *data,
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct ref *ref = remote_refs;
+	struct strbuf err = STRBUF_INIT;
 	int ret = 0;
 
 	for (;;) {
@@ -752,7 +753,11 @@ static int push_update_refs_status(struct helper_data *data,
 		private = apply_refspecs(data->refspecs, data->refspec_nr, ref->name);
 		if (!private)
 			continue;
-		update_ref("update by helper", private, ref->new_sha1, NULL, 0, 0);
+		if (update_ref("update by helper", private, ref->new_sha1,
+			       NULL, 0, &err))
+			error("%s", err.buf);
+		strbuf_release(&err);
+
 		free(private);
 	}
 	strbuf_release(&buf);
diff --git a/transport.c b/transport.c
index 70d38e4..f70d62f 100644
--- a/transport.c
+++ b/transport.c
@@ -597,6 +597,7 @@ int transport_refs_pushed(struct ref *ref)
 void transport_update_tracking_ref(struct remote *remote, struct ref *ref, int verbose)
 {
 	struct refspec rs;
+	struct strbuf err = STRBUF_INIT;
 
 	if (ref->status != REF_STATUS_OK && ref->status != REF_STATUS_UPTODATE)
 		return;
@@ -609,9 +610,11 @@ void transport_update_tracking_ref(struct remote *remote, struct ref *ref, int v
 			fprintf(stderr, "updating local tracking ref '%s'\n", rs.dst);
 		if (ref->deletion) {
 			delete_ref(rs.dst, NULL, 0);
-		} else
-			update_ref("update by push", rs.dst,
-					ref->new_sha1, NULL, 0, 0);
+		} else if (update_ref("update by push", rs.dst,
+				      ref->new_sha1, NULL, 0, &err))
+			error("%s", err.buf);
+
+		strbuf_release(&err);
 		free(rs.dst);
 	}
 }
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 14/16] refs.c: make add_packed_ref return an error instead of calling die

[Ronnie Sahlberg]

Change add_packed_ref to return an error instead of calling die().
Update all callers to check the return value of add_packed_ref.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/refs.c b/refs.c
index b59e2b8..0829c55 100644
--- a/refs.c
+++ b/refs.c
@@ -1229,15 +1229,16 @@ static struct ref_dir *get_packed_refs(struct ref_cache *refs)
 	return get_packed_ref_dir(get_packed_ref_cache(refs));
 }
 
-static void add_packed_ref(const char *refname, const unsigned char *sha1)
+static int add_packed_ref(const char *refname, const unsigned char *sha1)
 {
 	struct packed_ref_cache *packed_ref_cache =
 		get_packed_ref_cache(&ref_cache);
 
 	if (!packed_ref_cache->lock)
-		die("internal error: packed refs not locked");
+		return -1;
 	add_ref(get_packed_ref_dir(packed_ref_cache),
 		create_ref_entry(refname, sha1, REF_ISPACKED, 1));
+	return 0;
 }
 
 /*
@@ -3827,7 +3828,13 @@ int transaction_commit(struct transaction *transaction,
 					sha1, NULL))
 			continue;
 
-		add_packed_ref(update->refname, sha1);
+		if (add_packed_ref(update->refname, sha1)) {
+			if (err)
+				strbuf_addf(err, "Failed to add %s to packed "
+					    "refs", update->refname);
+			ret = -1;
+			goto cleanup;
+		}
 		need_repack = 1;
 	}
 	if (need_repack) {
@@ -3941,7 +3948,13 @@ int transaction_commit(struct transaction *transaction,
 
 		packed = get_packed_refs(&ref_cache);
 		remove_entry(packed, update->refname);
-		add_packed_ref(update->refname, update->new_sha1);
+		if (add_packed_ref(update->refname, update->new_sha1)) {
+			if (err)
+				strbuf_addf(err, "Failed to add %s to packed "
+					    "refs", update->refname);
+			ret = -1;
+			goto cleanup;
+		}
 		need_repack = 1;
 
 		try_remove_empty_parents((char *)update->refname);
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 15/16] refs.c: make lock_packed_refs take an err argument

[Ronnie Sahlberg]

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/refs.c b/refs.c
index 0829c55..1314a9a 100644
--- a/refs.c
+++ b/refs.c
@@ -2398,13 +2398,17 @@ static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
 	return 0;
 }
 
-/* This should return a meaningful errno on failure */
-static int lock_packed_refs(int flags)
+static int lock_packed_refs(struct strbuf *err)
 {
 	struct packed_ref_cache *packed_ref_cache;
 
-	if (hold_lock_file_for_update(&packlock, git_path("packed-refs"), flags) < 0)
+	if (hold_lock_file_for_update(&packlock, git_path("packed-refs"),
+				      0) < 0) {
+		if (err)
+			unable_to_lock_message(git_path("packed-refs"),
+					       errno, err);
 		return -1;
+	}
 	/*
 	 * Get the current packed-refs while holding the lock.  If the
 	 * packed-refs file has been modified since we last read it,
@@ -2592,11 +2596,14 @@ static void prune_refs(struct ref_to_prune *r)
 int pack_refs(unsigned int flags)
 {
 	struct pack_refs_cb_data cbdata;
+	struct strbuf err = STRBUF_INIT;
 
 	memset(&cbdata, 0, sizeof(cbdata));
 	cbdata.flags = flags;
 
-	lock_packed_refs(LOCK_DIE_ON_ERROR);
+	if (lock_packed_refs(&err))
+		die("%s", err.buf);
+
 	cbdata.packed_refs = get_packed_refs(&ref_cache);
 
 	do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
@@ -3789,10 +3796,7 @@ int transaction_commit(struct transaction *transaction,
 	}
 
 	/* Lock packed refs during commit */
-	if (lock_packed_refs(0)) {
-		if (err)
-			unable_to_lock_message(git_path("packed-refs"),
-					       errno, err);
+	if (lock_packed_refs(err)) {
 		ret = -1;
 		goto cleanup;
 	}
@@ -3847,10 +3851,7 @@ int transaction_commit(struct transaction *transaction,
 			goto cleanup;
 		}
 		/* lock the packed refs again so no one can change it */
-		if (lock_packed_refs(0)) {
-			if (err)
-				unable_to_lock_message(git_path("packed-refs"),
-						       errno, err);
+		if (lock_packed_refs(err)) {
 			ret = -1;
 			goto cleanup;
 		}
-- 
2.1.0.rc2.206.gedb03e5

[PATCH v3 16/16] refs.c: add an err argument to pack_refs

[Ronnie Sahlberg]

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/pack-refs.c | 8 +++++++-
 refs.c              | 7 +++----
 refs.h              | 3 ++-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/builtin/pack-refs.c b/builtin/pack-refs.c
index b20b1ec..299768e 100644
--- a/builtin/pack-refs.c
+++ b/builtin/pack-refs.c
@@ -10,6 +10,7 @@ static char const * const pack_refs_usage[] = {
 int cmd_pack_refs(int argc, const char **argv, const char *prefix)
 {
 	unsigned int flags = PACK_REFS_PRUNE;
+	struct strbuf err = STRBUF_INIT;
 	struct option opts[] = {
 		OPT_BIT(0, "all",   &flags, N_("pack everything"), PACK_REFS_ALL),
 		OPT_BIT(0, "prune", &flags, N_("prune loose refs (default)"), PACK_REFS_PRUNE),
@@ -17,5 +18,10 @@ int cmd_pack_refs(int argc, const char **argv, const char *prefix)
 	};
 	if (parse_options(argc, argv, prefix, opts, pack_refs_usage, 0))
 		usage_with_options(pack_refs_usage, opts);
-	return pack_refs(flags);
+	if (pack_refs(flags, &err)) {
+		error("%s", err.buf);
+		strbuf_release(&err);
+		return -1;
+	}
+	return 0;
 }
diff --git a/refs.c b/refs.c
index 1314a9a..cafb4aa 100644
--- a/refs.c
+++ b/refs.c
@@ -2593,16 +2593,15 @@ static void prune_refs(struct ref_to_prune *r)
 	}
 }
 
-int pack_refs(unsigned int flags)
+int pack_refs(unsigned int flags, struct strbuf *err)
 {
 	struct pack_refs_cb_data cbdata;
-	struct strbuf err = STRBUF_INIT;
 
 	memset(&cbdata, 0, sizeof(cbdata));
 	cbdata.flags = flags;
 
-	if (lock_packed_refs(&err))
-		die("%s", err.buf);
+	if (lock_packed_refs(err))
+		return -1;
 
 	cbdata.packed_refs = get_packed_refs(&ref_cache);
 
diff --git a/refs.h b/refs.h
index b5ba685..489aa9d 100644
--- a/refs.h
+++ b/refs.h
@@ -130,8 +130,9 @@ extern void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct st
 /*
  * Write a packed-refs file for the current repository.
  * flags: Combination of the above PACK_REFS_* flags.
+ * Returns 0 on success and fills in err on failure.
  */
-int pack_refs(unsigned int flags);
+int pack_refs(unsigned int flags, struct strbuf *err);
 
 extern int ref_exists(const char *);
 
-- 
2.1.0.rc2.206.gedb03e5