From cac4b8e22ee39e52341d718450f8e4055c4dc16f Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 30 Apr 2020 13:48:57 -0600 Subject: shallow: use struct 'shallow_lock' for additional safety In previous patches, the functions 'commit_shallow_file' and 'rollback_shallow_file' were introduced to reset the shallowness validity checks on a repository after potentially modifying '.git/shallow'. These functions can be made safer by wrapping the 'struct lockfile *' in a new type, 'shallow_lock', so that they cannot be called with a raw lock (and potentially misused by other code that happens to possess a lockfile, but has nothing to do with shallowness). This patch introduces that type as a thin wrapper around 'struct lockfile', and updates the two aforementioned functions and their callers to use it. Suggested-by: Junio C Hamano Helped-by: Jonathan Nieder Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano --- builtin/receive-pack.c | 2 +- fetch-pack.c | 2 +- shallow.c | 22 +++++++++++----------- shallow.h | 21 ++++++++++++++++++--- 4 files changed, 31 insertions(+), 16 deletions(-) diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c index 8e3f9bc35f..73cebc2f55 100644 --- a/builtin/receive-pack.c +++ b/builtin/receive-pack.c @@ -856,7 +856,7 @@ static void refuse_unconfigured_deny_delete_current(void) static int command_singleton_iterator(void *cb_data, struct object_id *oid); static int update_shallow_ref(struct command *cmd, struct shallow_info *si) { - struct lock_file shallow_lock = LOCK_INIT; + struct shallow_lock shallow_lock = SHALLOW_LOCK_INIT; struct oid_array extra = OID_ARRAY_INIT; struct check_connected_options opt = CHECK_CONNECTED_INIT; uint32_t mask = 1 << (cmd->index % 32); diff --git a/fetch-pack.c b/fetch-pack.c index 401d028e41..27d2d08cc0 100644 --- a/fetch-pack.c +++ b/fetch-pack.c @@ -35,7 +35,7 @@ static int fetch_fsck_objects = -1; static int transfer_fsck_objects = -1; static int agent_supported; static int server_supports_filtering; -static struct lock_file shallow_lock; +static struct shallow_lock shallow_lock; static const char *alternate_shallow_file; static struct strbuf fsck_msg_types = STRBUF_INIT; diff --git a/shallow.c b/shallow.c index 76e00893fe..7e0a41ea68 100644 --- a/shallow.c +++ b/shallow.c @@ -92,16 +92,16 @@ static void reset_repository_shallow(struct repository *r) stat_validity_clear(r->parsed_objects->shallow_stat); } -int commit_shallow_file(struct repository *r, struct lock_file *lk) +int commit_shallow_file(struct repository *r, struct shallow_lock *lk) { - int res = commit_lock_file(lk); + int res = commit_lock_file(&lk->lock); reset_repository_shallow(r); return res; } -void rollback_shallow_file(struct repository *r, struct lock_file *lk) +void rollback_shallow_file(struct repository *r, struct shallow_lock *lk) { - rollback_lock_file(lk); + rollback_lock_file(&lk->lock); reset_repository_shallow(r); } @@ -366,22 +366,22 @@ const char *setup_temporary_shallow(const struct oid_array *extra) return ""; } -void setup_alternate_shallow(struct lock_file *shallow_lock, +void setup_alternate_shallow(struct shallow_lock *shallow_lock, const char **alternate_shallow_file, const struct oid_array *extra) { struct strbuf sb = STRBUF_INIT; int fd; - fd = hold_lock_file_for_update(shallow_lock, + fd = hold_lock_file_for_update(&shallow_lock->lock, git_path_shallow(the_repository), LOCK_DIE_ON_ERROR); check_shallow_file_for_update(the_repository); if (write_shallow_commits(&sb, 0, extra)) { if (write_in_full(fd, sb.buf, sb.len) < 0) die_errno("failed to write to %s", - get_lock_file_path(shallow_lock)); - *alternate_shallow_file = get_lock_file_path(shallow_lock); + get_lock_file_path(&shallow_lock->lock)); + *alternate_shallow_file = get_lock_file_path(&shallow_lock->lock); } else /* * is_repository_shallow() sees empty string as "no @@ -414,7 +414,7 @@ void advertise_shallow_grafts(int fd) */ void prune_shallow(unsigned options) { - struct lock_file shallow_lock = LOCK_INIT; + struct shallow_lock shallow_lock = SHALLOW_LOCK_INIT; struct strbuf sb = STRBUF_INIT; unsigned flags = SEEN_ONLY; int fd; @@ -428,14 +428,14 @@ void prune_shallow(unsigned options) strbuf_release(&sb); return; } - fd = hold_lock_file_for_update(&shallow_lock, + fd = hold_lock_file_for_update(&shallow_lock.lock, git_path_shallow(the_repository), LOCK_DIE_ON_ERROR); check_shallow_file_for_update(the_repository); if (write_shallow_commits_1(&sb, 0, NULL, flags)) { if (write_in_full(fd, sb.buf, sb.len) < 0) die_errno("failed to write to %s", - get_lock_file_path(&shallow_lock)); + get_lock_file_path(&shallow_lock.lock)); commit_shallow_file(the_repository, &shallow_lock); } else { unlink(git_path_shallow(the_repository)); diff --git a/shallow.h b/shallow.h index b3bf200bf9..5b4a96dcd6 100644 --- a/shallow.h +++ b/shallow.h @@ -10,10 +10,25 @@ void set_alternate_shallow_file(struct repository *r, const char *path, int over int register_shallow(struct repository *r, const struct object_id *oid); int unregister_shallow(const struct object_id *oid); int is_repository_shallow(struct repository *r); + +/* + * Lock for updating the $GIT_DIR/shallow file. + * + * Use `commit_shallow_file()` to commit an update, or + * `rollback_shallow_file()` to roll it back. In either case, any + * in-memory cached information about which commits are shallow will be + * appropriately invalidated so that future operations reflect the new + * state. + */ +struct shallow_lock { + struct lock_file lock; +}; +#define SHALLOW_LOCK_INIT { LOCK_INIT } + /* commit $GIT_DIR/shallow and reset stat-validity checks */ -int commit_shallow_file(struct repository *r, struct lock_file *lk); +int commit_shallow_file(struct repository *r, struct shallow_lock *lk); /* rollback $GIT_DIR/shallow and reset stat-validity checks */ -void rollback_shallow_file(struct repository *r, struct lock_file *lk); +void rollback_shallow_file(struct repository *r, struct shallow_lock *lk); struct commit_list *get_shallow_commits(struct object_array *heads, int depth, int shallow_flag, int not_shallow_flag); @@ -22,7 +37,7 @@ struct commit_list *get_shallow_commits_by_rev_list( int write_shallow_commits(struct strbuf *out, int use_pack_protocol, const struct oid_array *extra); -void setup_alternate_shallow(struct lock_file *shallow_lock, +void setup_alternate_shallow(struct shallow_lock *shallow_lock, const char **alternate_shallow_file, const struct oid_array *extra); -- cgit v1.2.3