free(lock);
}
+/*
+ * Lock refname, without following symrefs, and set *lock_p to point
+ * at a newly-allocated lock object. Fill in lock->old_oid, referent,
+ * and type similarly to read_raw_ref().
+ *
+ * The caller must verify that refname is a "safe" reference name (in
+ * the sense of refname_is_safe()) before calling this function.
+ *
+ * If the reference doesn't already exist, verify that refname doesn't
+ * have a D/F conflict with any existing references. extras and skip
+ * are passed to verify_refname_available_dir() for this check.
+ *
+ * If mustexist is not set and the reference is not found or is
+ * broken, lock the reference anyway but clear sha1.
+ *
+ * Return 0 on success. On failure, write an error message to err and
+ * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
+ *
+ * Implementation note: This function is basically
+ *
+ * lock reference
+ * read_raw_ref()
+ *
+ * but it includes a lot more code to
+ * - Deal with possible races with other processes
+ * - Avoid calling verify_refname_available_dir() when it can be
+ * avoided, namely if we were successfully able to read the ref
+ * - Generate informative error messages in the case of failure
+ */
+static int lock_raw_ref(const char *refname, int mustexist,
+ const struct string_list *extras,
+ const struct string_list *skip,
+ struct ref_lock **lock_p,
+ struct strbuf *referent,
+ unsigned int *type,
+ struct strbuf *err)
+{
+ struct ref_lock *lock;
+ struct strbuf ref_file = STRBUF_INIT;
+ int attempts_remaining = 3;
+ int ret = TRANSACTION_GENERIC_ERROR;
+
+ assert(err);
+ *type = 0;
+
+ /* First lock the file so it can't change out from under us. */
+
+ *lock_p = lock = xcalloc(1, sizeof(*lock));
+
+ lock->ref_name = xstrdup(refname);
+ lock->orig_ref_name = xstrdup(refname);
+ strbuf_git_path(&ref_file, "%s", refname);
+
+retry:
+ switch (safe_create_leading_directories(ref_file.buf)) {
+ case SCLD_OK:
+ break; /* success */
+ case SCLD_EXISTS:
+ /*
+ * Suppose refname is "refs/foo/bar". We just failed
+ * to create the containing directory, "refs/foo",
+ * because there was a non-directory in the way. This
+ * indicates a D/F conflict, probably because of
+ * another reference such as "refs/foo". There is no
+ * reason to expect this error to be transitory.
+ */
+ if (verify_refname_available(refname, extras, skip, err)) {
+ if (mustexist) {
+ /*
+ * To the user the relevant error is
+ * that the "mustexist" reference is
+ * missing:
+ */
+ strbuf_reset(err);
+ strbuf_addf(err, "unable to resolve reference '%s'",
+ refname);
+ } else {
+ /*
+ * The error message set by
+ * verify_refname_available_dir() is OK.
+ */
+ ret = TRANSACTION_NAME_CONFLICT;
+ }
+ } else {
+ /*
+ * The file that is in the way isn't a loose
+ * reference. Report it as a low-level
+ * failure.
+ */
+ strbuf_addf(err, "unable to create lock file %s.lock; "
+ "non-directory in the way",
+ ref_file.buf);
+ }
+ goto error_return;
+ case SCLD_VANISHED:
+ /* Maybe another process was tidying up. Try again. */
+ if (--attempts_remaining > 0)
+ goto retry;
+ /* fall through */
+ default:
+ strbuf_addf(err, "unable to create directory for %s",
+ ref_file.buf);
+ goto error_return;
+ }
+
+ if (!lock->lk)
+ lock->lk = xcalloc(1, sizeof(struct lock_file));
+
+ if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
+ if (errno == ENOENT && --attempts_remaining > 0) {
+ /*
+ * Maybe somebody just deleted one of the
+ * directories leading to ref_file. Try
+ * again:
+ */
+ goto retry;
+ } else {
+ unable_to_lock_message(ref_file.buf, errno, err);
+ goto error_return;
+ }
+ }
+
+ /*
+ * Now we hold the lock and can read the reference without
+ * fear that its value will change.
+ */
+
+ if (read_raw_ref(refname, lock->old_oid.hash, referent, type)) {
+ if (errno == ENOENT) {
+ if (mustexist) {
+ /* Garden variety missing reference. */
+ strbuf_addf(err, "unable to resolve reference '%s'",
+ refname);
+ goto error_return;
+ } else {
+ /*
+ * Reference is missing, but that's OK. We
+ * know that there is not a conflict with
+ * another loose reference because
+ * (supposing that we are trying to lock
+ * reference "refs/foo/bar"):
+ *
+ * - We were successfully able to create
+ * the lockfile refs/foo/bar.lock, so we
+ * know there cannot be a loose reference
+ * named "refs/foo".
+ *
+ * - We got ENOENT and not EISDIR, so we
+ * know that there cannot be a loose
+ * reference named "refs/foo/bar/baz".
+ */
+ }
+ } else if (errno == EISDIR) {
+ /*
+ * There is a directory in the way. It might have
+ * contained references that have been deleted. If
+ * we don't require that the reference already
+ * exists, try to remove the directory so that it
+ * doesn't cause trouble when we want to rename the
+ * lockfile into place later.
+ */
+ if (mustexist) {
+ /* Garden variety missing reference. */
+ strbuf_addf(err, "unable to resolve reference '%s'",
+ refname);
+ goto error_return;
+ } else if (remove_dir_recursively(&ref_file,
+ REMOVE_DIR_EMPTY_ONLY)) {
+ if (verify_refname_available_dir(
+ refname, extras, skip,
+ get_loose_refs(&ref_cache),
+ err)) {
+ /*
+ * The error message set by
+ * verify_refname_available() is OK.
+ */
+ ret = TRANSACTION_NAME_CONFLICT;
+ goto error_return;
+ } else {
+ /*
+ * We can't delete the directory,
+ * but we also don't know of any
+ * references that it should
+ * contain.
+ */
+ strbuf_addf(err, "there is a non-empty directory '%s' "
+ "blocking reference '%s'",
+ ref_file.buf, refname);
+ goto error_return;
+ }
+ }
+ } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
+ strbuf_addf(err, "unable to resolve reference '%s': "
+ "reference broken", refname);
+ goto error_return;
+ } else {
+ strbuf_addf(err, "unable to resolve reference '%s': %s",
+ refname, strerror(errno));
+ goto error_return;
+ }
+
+ /*
+ * If the ref did not exist and we are creating it,
+ * make sure there is no existing packed ref whose
+ * name begins with our refname, nor a packed ref
+ * whose name is a proper prefix of our refname.
+ */
+ if (verify_refname_available_dir(
+ refname, extras, skip,
+ get_packed_refs(&ref_cache),
+ err)) {
+ goto error_return;
+ }
+ }
+
+ ret = 0;
+ goto out;
+
+error_return:
+ unlock_ref(lock);
+ *lock_p = NULL;
+
+out:
+ strbuf_release(&ref_file);
+ return ret;
+}
+
/*
* Peel the entry (if possible) and return its new peel_status. If
* repeel is true, re-peel the entry even if there is an old peeled
}
/*
- * Acquire all locks, verify old values if provided, check
- * that new values are valid, and write new values to the
- * lockfiles, ready to be activated. Only keep one lockfile
- * open at a time to avoid running out of file descriptors.
+ * If update is a direct update of head_ref (the reference pointed to
+ * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
+ */
+static int split_head_update(struct ref_update *update,
+ struct ref_transaction *transaction,
+ const char *head_ref,
+ struct string_list *affected_refnames,
+ struct strbuf *err)
+{
+ struct string_list_item *item;
+ struct ref_update *new_update;
+
+ if ((update->flags & REF_LOG_ONLY) ||
+ (update->flags & REF_ISPRUNING) ||
+ (update->flags & REF_UPDATE_VIA_HEAD))
+ return 0;
+
+ if (strcmp(update->refname, head_ref))
+ return 0;
+
+ /*
+ * First make sure that HEAD is not already in the
+ * transaction. This insertion is O(N) in the transaction
+ * size, but it happens at most once per transaction.
+ */
+ item = string_list_insert(affected_refnames, "HEAD");
+ if (item->util) {
+ /* An entry already existed */
+ strbuf_addf(err,
+ "multiple updates for 'HEAD' (including one "
+ "via its referent '%s') are not allowed",
+ update->refname);
+ return TRANSACTION_NAME_CONFLICT;
+ }
+
+ new_update = ref_transaction_add_update(
+ transaction, "HEAD",
+ update->flags | REF_LOG_ONLY | REF_NODEREF,
+ update->new_sha1, update->old_sha1,
+ update->msg);
+
+ item->util = new_update;
+
+ return 0;
+}
+
+/*
+ * update is for a symref that points at referent and doesn't have
+ * REF_NODEREF set. Split it into two updates:
+ * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
+ * - A new, separate update for the referent reference
+ * Note that the new update will itself be subject to splitting when
+ * the iteration gets to it.
+ */
+static int split_symref_update(struct ref_update *update,
+ const char *referent,
+ struct ref_transaction *transaction,
+ struct string_list *affected_refnames,
+ struct strbuf *err)
+{
+ struct string_list_item *item;
+ struct ref_update *new_update;
+ unsigned int new_flags;
+
+ /*
+ * First make sure that referent is not already in the
+ * transaction. This insertion is O(N) in the transaction
+ * size, but it happens at most once per symref in a
+ * transaction.
+ */
+ item = string_list_insert(affected_refnames, referent);
+ if (item->util) {
+ /* An entry already existed */
+ strbuf_addf(err,
+ "multiple updates for '%s' (including one "
+ "via symref '%s') are not allowed",
+ referent, update->refname);
+ return TRANSACTION_NAME_CONFLICT;
+ }
+
+ new_flags = update->flags;
+ if (!strcmp(update->refname, "HEAD")) {
+ /*
+ * Record that the new update came via HEAD, so that
+ * when we process it, split_head_update() doesn't try
+ * to add another reflog update for HEAD. Note that
+ * this bit will be propagated if the new_update
+ * itself needs to be split.
+ */
+ new_flags |= REF_UPDATE_VIA_HEAD;
+ }
+
+ new_update = ref_transaction_add_update(
+ transaction, referent, new_flags,
+ update->new_sha1, update->old_sha1,
+ update->msg);
+
+ /* Change the symbolic ref update to log only: */
+ update->flags |= REF_LOG_ONLY | REF_NODEREF;
+
+ item->util = new_update;
+
+ return 0;
+}
+
+/*
+ * Prepare for carrying out update:
+ * - Lock the reference referred to by update.
+ * - Read the reference under lock.
+ * - Check that its old SHA-1 value (if specified) is correct, and in
+ * any case record it in update->lock->old_oid for later use when
+ * writing the reflog.
+ * - If it is a symref update without REF_NODEREF, split it up into a
+ * REF_LOG_ONLY update of the symref and add a separate update for
+ * the referent to transaction.
+ * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
+ * update of HEAD.
*/
static int lock_ref_for_update(struct ref_update *update,
struct ref_transaction *transaction,
+ const char *head_ref,
struct string_list *affected_refnames,
struct strbuf *err)
{
+ struct strbuf referent = STRBUF_INIT;
+ int mustexist = (update->flags & REF_HAVE_OLD) &&
+ !is_null_sha1(update->old_sha1);
int ret;
+ struct ref_lock *lock;
- if ((update->flags & REF_HAVE_NEW) &&
- is_null_sha1(update->new_sha1))
+ if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
update->flags |= REF_DELETING;
- update->lock = lock_ref_sha1_basic(
- update->refname,
- ((update->flags & REF_HAVE_OLD) ?
- update->old_sha1 : NULL),
- affected_refnames, NULL,
- update->flags,
- &update->type,
- err);
- if (!update->lock) {
+
+ if (head_ref) {
+ ret = split_head_update(update, transaction, head_ref,
+ affected_refnames, err);
+ if (ret)
+ return ret;
+ }
+
+ ret = lock_raw_ref(update->refname, mustexist,
+ affected_refnames, NULL,
+ &update->lock, &referent,
+ &update->type, err);
+
+ if (ret) {
char *reason;
- ret = (errno == ENOTDIR)
- ? TRANSACTION_NAME_CONFLICT
- : TRANSACTION_GENERIC_ERROR;
reason = strbuf_detach(err, NULL);
strbuf_addf(err, "cannot lock ref '%s': %s",
update->refname, reason);
free(reason);
return ret;
}
+
+ lock = update->lock;
+
+ if (read_ref_full(update->refname,
+ mustexist ? RESOLVE_REF_READING : 0,
+ lock->old_oid.hash, NULL)) {
+ if (update->flags & REF_HAVE_OLD) {
+ strbuf_addf(err, "cannot lock ref '%s': can't resolve old value",
+ update->refname);
+ return TRANSACTION_GENERIC_ERROR;
+ } else {
+ hashclr(lock->old_oid.hash);
+ }
+ }
+ if ((update->flags & REF_HAVE_OLD) &&
+ hashcmp(lock->old_oid.hash, update->old_sha1)) {
+ strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s",
+ update->refname,
+ sha1_to_hex(lock->old_oid.hash),
+ sha1_to_hex(update->old_sha1));
+ return TRANSACTION_GENERIC_ERROR;
+ }
+
+ if (update->type & REF_ISSYMREF) {
+ if (!(update->flags & REF_NODEREF)) {
+ ret = split_symref_update(update, referent.buf, transaction,
+ affected_refnames, err);
+ if (ret)
+ return ret;
+ }
+ }
+
if ((update->flags & REF_HAVE_NEW) &&
!(update->flags & REF_DELETING) &&
!(update->flags & REF_LOG_ONLY)) {
- int overwriting_symref = ((update->type & REF_ISSYMREF) &&
- (update->flags & REF_NODEREF));
-
- if (!overwriting_symref &&
- !hashcmp(update->lock->old_oid.hash, update->new_sha1)) {
+ if (!(update->type & REF_ISSYMREF) &&
+ !hashcmp(lock->old_oid.hash, update->new_sha1)) {
/*
* The reference already has the desired
* value, so we don't need to write it.
*/
- } else if (write_ref_to_lockfile(update->lock,
- update->new_sha1,
+ } else if (write_ref_to_lockfile(lock, update->new_sha1,
err)) {
char *write_err = strbuf_detach(err, NULL);
* the lockfile is still open. Close it to
* free up the file descriptor:
*/
- if (close_ref(update->lock)) {
+ if (close_ref(lock)) {
strbuf_addf(err, "couldn't close '%s.lock'",
update->refname);
return TRANSACTION_GENERIC_ERROR;
struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
struct string_list_item *ref_to_delete;
struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+ char *head_ref = NULL;
+ int head_type;
+ struct object_id head_oid;
assert(err);
return 0;
}
- /* Fail if a refname appears more than once in the transaction: */
- for (i = 0; i < transaction->nr; i++)
- string_list_append(&affected_refnames,
- transaction->updates[i]->refname);
+ /*
+ * Fail if a refname appears more than once in the
+ * transaction. (If we end up splitting up any updates using
+ * split_symref_update() or split_head_update(), those
+ * functions will check that the new updates don't have the
+ * same refname as any existing ones.)
+ */
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+ struct string_list_item *item =
+ string_list_append(&affected_refnames, update->refname);
+
+ /*
+ * We store a pointer to update in item->util, but at
+ * the moment we never use the value of this field
+ * except to check whether it is non-NULL.
+ */
+ item->util = update;
+ }
string_list_sort(&affected_refnames);
if (ref_update_reject_duplicates(&affected_refnames, err)) {
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
}
+ /*
+ * 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 would require reverse symref lookups,
+ * but finding all symrefs pointing to a 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).
+ *
+ * So if HEAD is a symbolic reference, then record the name of
+ * the reference that it points to. If we see an update of
+ * head_ref within the transaction, then split_head_update()
+ * arranges for the reflog of HEAD to be updated, too.
+ */
+ head_ref = resolve_refdup("HEAD", RESOLVE_REF_NO_RECURSE,
+ head_oid.hash, &head_type);
+
+ if (head_ref && !(head_type & REF_ISSYMREF)) {
+ free(head_ref);
+ head_ref = NULL;
+ }
+
/*
* Acquire all locks, verify old values if provided, check
* that new values are valid, and write new values to the
for (i = 0; i < transaction->nr; i++) {
struct ref_update *update = transaction->updates[i];
- ret = lock_ref_for_update(update, transaction,
+ ret = lock_ref_for_update(update, transaction, head_ref,
&affected_refnames, err);
if (ret)
goto cleanup;
/* Perform updates first so live commits remain referenced */
for (i = 0; i < transaction->nr; i++) {
struct ref_update *update = transaction->updates[i];
+ struct ref_lock *lock = update->lock;
if (update->flags & REF_NEEDS_COMMIT ||
update->flags & REF_LOG_ONLY) {
- if (commit_ref_update(update->lock,
- update->new_sha1, update->msg,
- update->flags, err)) {
- /* freed by commit_ref_update(): */
+ if (log_ref_write(lock->ref_name, lock->old_oid.hash,
+ update->new_sha1,
+ update->msg, update->flags, err)) {
+ char *old_msg = strbuf_detach(err, NULL);
+
+ strbuf_addf(err, "cannot update the ref '%s': %s",
+ lock->ref_name, old_msg);
+ free(old_msg);
+ unlock_ref(lock);
update->lock = NULL;
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
- } else {
- /* freed by commit_ref_update(): */
+ }
+ }
+ if (update->flags & REF_NEEDS_COMMIT) {
+ clear_loose_ref_cache(&ref_cache);
+ if (commit_ref(lock)) {
+ strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
+ unlock_ref(lock);
update->lock = NULL;
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
}
}
}
-
/* Perform deletes now that updates are safely completed */
for (i = 0; i < transaction->nr; i++) {
struct ref_update *update = transaction->updates[i];
if (transaction->updates[i]->lock)
unlock_ref(transaction->updates[i]->lock);
string_list_clear(&refs_to_delete, 0);
+ free(head_ref);
string_list_clear(&affected_refnames, 0);
+
return ret;
}