[PATCH 8/8] reftable/stack: fix stale lock when dying
- From
Patrick Steinhardt <ps@pks.im>
- Date
- Nov 21, 2023, 07:04 UTC
- Message-ID
- <065c8803ac18633313af264f70c83717c4f6e10c.1700549493.git.ps@pks.im>
- In-Reply-To
- <cover.1700549493.git.ps@pks.im>
When starting a transaction via `reftable_stack_init_addition()`, we create a lockfile for the reftable stack itself which we'll write the new list of tables to. But if we terminate abnormally e.g. via a call to `die()`, then we do not remove the lockfile. Subsequent executions of Git which try to modify references will thus fail with an out-of-date error.
Fix this bug by registering the lock as a `struct tempfile`, which ensures automatic cleanup for us.
Signed-off-by: Patrick Steinhardt <ps@pks.im> --- reftable/stack.c | 47 +++++++++++++++-------------------------------- 1 file changed, 15 insertions(+), 32 deletions(-)
diff --git a/reftable/stack.c b/reftable/stack.c index 2dd2373360..2f1494aef2 100644 --- a/reftable/stack.c +++ b/reftable/stack.c @@ -17,6 +17,8 @@ license that can be found in the LICENSE file or at #include "reftable-merged.h" #include "writer.h" +#include "tempfile.h" + static int stack_try_add(struct reftable_stack *st, int (*write_table)(struct reftable_writer *wr, void *arg), @@ -440,8 +442,7 @@ static void format_name(struct strbuf *dest, uint64_t min, uint64_t max) } struct reftable_addition { - int lock_file_fd; - struct strbuf lock_file_name; + struct tempfile *lock_file; struct reftable_stack *stack; char **new_tables; @@ -449,24 +450,19 @@ struct reftable_addition { uint64_t next_update_index; }; -#define REFTABLE_ADDITION_INIT \ - { \ - .lock_file_name = STRBUF_INIT \ - } +#define REFTABLE_ADDITION_INIT {0} static int reftable_stack_init_addition(struct reftable_addition *add, struct reftable_stack *st) { + struct strbuf lock_file_name = STRBUF_INIT; int err = 0; add->stack = st; - strbuf_reset(&add->lock_file_name); - strbuf_addstr(&add->lock_file_name, st->list_file); - strbuf_addstr(&add->lock_file_name, ".lock"); + strbuf_addf(&lock_file_name, "%s.lock", st->list_file); - add->lock_file_fd = open(add->lock_file_name.buf, - O_EXCL | O_CREAT | O_WRONLY, 0666); - if (add->lock_file_fd < 0) { + add->lock_file = create_tempfile(lock_file_name.buf); + if (!add->lock_file) { if (errno == EEXIST) { err = REFTABLE_LOCK_ERROR; } else { @@ -475,7 +471,7 @@ static int reftable_stack_init_addition(struct reftable_addition *add, goto done; } if (st->config.default_permissions) { - if (chmod(add->lock_file_name.buf, st->config.default_permissions) < 0) { + if (chmod(lock_file_name.buf, st->config.default_permissions) < 0) { err = REFTABLE_IO_ERROR; goto done; } @@ -495,6 +491,7 @@ static int reftable_stack_init_addition(struct reftable_addition *add, if (err) { reftable_addition_close(add); } + strbuf_release(&lock_file_name); return err; } @@ -512,15 +509,7 @@ static void reftable_addition_close(struct reftable_addition *add) add->new_tables = NULL; add->new_tables_len = 0; - if (add->lock_file_fd > 0) { - close(add->lock_file_fd); - add->lock_file_fd = 0; - } - if (add->lock_file_name.len > 0) { - unlink(add->lock_file_name.buf); - strbuf_release(&add->lock_file_name); - } - + delete_tempfile(&add->lock_file); strbuf_release(&nm); } @@ -536,8 +525,10 @@ void reftable_addition_destroy(struct reftable_addition *add) int reftable_addition_commit(struct reftable_addition *add) { struct strbuf table_list = STRBUF_INIT; + int lock_file_fd = get_tempfile_fd(add->lock_file); int i = 0; int err = 0; + if (add->new_tables_len == 0) goto done; @@ -550,28 +541,20 @@ int reftable_addition_commit(struct reftable_addition *add) strbuf_addstr(&table_list, "\n"); } - err = write_in_full(add->lock_file_fd, table_list.buf, table_list.len); + err = write_in_full(lock_file_fd, table_list.buf, table_list.len); strbuf_release(&table_list); if (err < 0) { err = REFTABLE_IO_ERROR; goto done; } - err = close(add->lock_file_fd); - add->lock_file_fd = 0; - if (err < 0) { - err = REFTABLE_IO_ERROR; - goto done; - } - - err = rename(add->lock_file_name.buf, add->stack->list_file); + err = rename_tempfile(&add->lock_file, add->stack->list_file); if (err < 0) { err = REFTABLE_IO_ERROR; goto done; } /* success, no more state to clean up. */ - strbuf_release(&add->lock_file_name); for (i = 0; i < add->new_tables_len; i++) { reftable_free(add->new_tables[i]); }
-- 2.42.0