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authorLibravatar Junio C Hamano <gitster@pobox.com>2015-05-12 21:26:09 -0700
committerLibravatar Junio C Hamano <gitster@pobox.com>2015-05-12 21:26:09 -0700
commit4ec6591dd7bb055a74f259ad4c360ecd8ded5f35 (patch)
tree9389945d76d6d94a59afcda2f77500eea05038c4
parentGit 2.3.7 (diff)
parentref_transaction_commit(): fix atomicity and avoid fd exhaustion (diff)
downloadtgif-4ec6591dd7bb055a74f259ad4c360ecd8ded5f35.tar.xz
Merge branch 'mh/write-refs-sooner-2.2' into mh/write-refs-sooner-2.3
* mh/write-refs-sooner-2.2: ref_transaction_commit(): fix atomicity and avoid fd exhaustion ref_transaction_commit(): remove the local flags variable ref_transaction_commit(): inline call to write_ref_sha1() rename_ref(): inline calls to write_ref_sha1() from this function commit_ref_update(): new function, extracted from write_ref_sha1() write_ref_to_lockfile(): new function, extracted from write_ref_sha1() t7004: rename ULIMIT test prerequisite to ULIMIT_STACK_SIZE update-ref: test handling large transactions properly
-rw-r--r--refs.c99
-rwxr-xr-xt/t1400-update-ref.sh28
-rwxr-xr-xt/t7004-tag.sh4
3 files changed, 103 insertions, 28 deletions
diff --git a/refs.c b/refs.c
index 3a26ad4e65..c689af6ccf 100644
--- a/refs.c
+++ b/refs.c
@@ -30,6 +30,13 @@ static unsigned char refname_disposition[256] = {
* pruned.
*/
#define REF_ISPRUNING 0x0100
+
+/*
+ * Used as a flag in ref_update::flags when the lockfile needs to be
+ * committed.
+ */
+#define REF_NEEDS_COMMIT 0x0200
+
/*
* Try to read one refname component from the front of refname.
* Return the length of the component found, or -1 if the component is
@@ -2747,8 +2754,9 @@ static int rename_ref_available(const char *oldname, const char *newname)
return ret;
}
-static int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1,
- const char *logmsg);
+static int write_ref_to_lockfile(struct ref_lock *lock, const unsigned char *sha1);
+static int commit_ref_update(struct ref_lock *lock,
+ const unsigned char *sha1, const char *logmsg);
int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
{
@@ -2807,7 +2815,9 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
}
lock->force_write = 1;
hashcpy(lock->old_sha1, orig_sha1);
- if (write_ref_sha1(lock, orig_sha1, logmsg)) {
+
+ if (write_ref_to_lockfile(lock, orig_sha1) ||
+ commit_ref_update(lock, orig_sha1, logmsg)) {
error("unable to write current sha1 into %s", newrefname);
goto rollback;
}
@@ -2824,7 +2834,8 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
lock->force_write = 1;
flag = log_all_ref_updates;
log_all_ref_updates = 0;
- if (write_ref_sha1(lock, orig_sha1, NULL))
+ if (write_ref_to_lockfile(lock, orig_sha1) ||
+ commit_ref_update(lock, orig_sha1, NULL))
error("unable to write current sha1 into %s", oldrefname);
log_all_ref_updates = flag;
@@ -2996,23 +3007,15 @@ int is_branch(const char *refname)
}
/*
- * Write sha1 into the ref specified by the lock. Make sure that errno
- * is sane on error.
+ * Write sha1 into the open lockfile, then close the lockfile. On
+ * errors, rollback the lockfile and set errno to reflect the problem.
*/
-static int write_ref_sha1(struct ref_lock *lock,
- const unsigned char *sha1, const char *logmsg)
+static int write_ref_to_lockfile(struct ref_lock *lock,
+ const unsigned char *sha1)
{
static char term = '\n';
struct object *o;
- if (!lock) {
- errno = EINVAL;
- return -1;
- }
- if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
- unlock_ref(lock);
- return 0;
- }
o = parse_object(sha1);
if (!o) {
error("Trying to write ref %s with nonexistent object %s",
@@ -3037,6 +3040,17 @@ static int write_ref_sha1(struct ref_lock *lock,
errno = save_errno;
return -1;
}
+ return 0;
+}
+
+/*
+ * Commit a change to a loose reference that has already been written
+ * to the loose reference lockfile. Also update the reflogs if
+ * necessary, using the specified lockmsg (which can be NULL).
+ */
+static int commit_ref_update(struct ref_lock *lock,
+ const unsigned char *sha1, const char *logmsg)
+{
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) &&
@@ -3738,19 +3752,23 @@ int ref_transaction_commit(struct ref_transaction *transaction,
goto cleanup;
}
- /* Acquire all locks while verifying old values */
+ /*
+ * 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.
+ */
for (i = 0; i < n; i++) {
struct ref_update *update = updates[i];
- int flags = update->flags;
if (is_null_sha1(update->new_sha1))
- flags |= REF_DELETING;
+ update->flags |= REF_DELETING;
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)
@@ -3760,22 +3778,51 @@ int ref_transaction_commit(struct ref_transaction *transaction,
update->refname);
goto cleanup;
}
+ if (!(update->flags & REF_DELETING) &&
+ (update->lock->force_write ||
+ hashcmp(update->lock->old_sha1, update->new_sha1))) {
+ if (write_ref_to_lockfile(update->lock, update->new_sha1)) {
+ /*
+ * The lock was freed upon failure of
+ * write_ref_to_lockfile():
+ */
+ update->lock = NULL;
+ strbuf_addf(err, "Cannot update the ref '%s'.",
+ update->refname);
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+ update->flags |= REF_NEEDS_COMMIT;
+ } else {
+ /*
+ * We didn't have to write anything to the lockfile.
+ * Close it to free up the file descriptor:
+ */
+ if (close_ref(update->lock)) {
+ strbuf_addf(err, "Couldn't close %s.lock",
+ update->refname);
+ goto cleanup;
+ }
+ }
}
/* Perform updates first so live commits remain referenced */
for (i = 0; i < n; i++) {
struct ref_update *update = updates[i];
- if (!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 */
+ if (update->flags & REF_NEEDS_COMMIT) {
+ if (commit_ref_update(update->lock,
+ update->new_sha1, update->msg)) {
+ /* The lock was freed by commit_ref_update(): */
+ update->lock = NULL;
strbuf_addf(err, "Cannot update the ref '%s'.",
update->refname);
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
+ } else {
+ /* freed by the above call: */
+ update->lock = NULL;
}
- update->lock = NULL; /* freed by write_ref_sha1 */
}
}
@@ -3783,7 +3830,7 @@ int ref_transaction_commit(struct ref_transaction *transaction,
for (i = 0; i < n; i++) {
struct ref_update *update = updates[i];
- if (update->lock) {
+ if (update->flags & REF_DELETING) {
if (delete_ref_loose(update->lock, update->type, err)) {
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 6805b9e6bb..636d3a167c 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -1065,4 +1065,32 @@ test_expect_success 'stdin -z delete refs works with packed and loose refs' '
test_must_fail git rev-parse --verify -q $c
'
+run_with_limited_open_files () {
+ (ulimit -n 32 && "$@")
+}
+
+test_lazy_prereq ULIMIT_FILE_DESCRIPTORS 'run_with_limited_open_files true'
+
+test_expect_success ULIMIT_FILE_DESCRIPTORS 'large transaction creating branches does not burst open file limit' '
+(
+ for i in $(test_seq 33)
+ do
+ echo "create refs/heads/$i HEAD"
+ done >large_input &&
+ run_with_limited_open_files git update-ref --stdin <large_input &&
+ git rev-parse --verify -q refs/heads/33
+)
+'
+
+test_expect_success ULIMIT_FILE_DESCRIPTORS 'large transaction deleting branches does not burst open file limit' '
+(
+ for i in $(test_seq 33)
+ do
+ echo "delete refs/heads/$i HEAD"
+ done >large_input &&
+ run_with_limited_open_files git update-ref --stdin <large_input &&
+ test_must_fail git rev-parse --verify -q refs/heads/33
+)
+'
+
test_done
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index 35c805a44e..5446060ffb 100755
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -1463,10 +1463,10 @@ run_with_limited_stack () {
(ulimit -s 128 && "$@")
}
-test_lazy_prereq ULIMIT 'run_with_limited_stack true'
+test_lazy_prereq ULIMIT_STACK_SIZE 'run_with_limited_stack true'
# we require ulimit, this excludes Windows
-test_expect_success ULIMIT '--contains works in a deep repo' '
+test_expect_success ULIMIT_STACK_SIZE '--contains works in a deep repo' '
>expect &&
i=1 &&
while test $i -lt 8000