From fa3bff2466ece4a10ba9beb9be3b45bada1c12eb Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Mon, 27 Apr 2020 10:27:58 -0600 Subject: [PATCH] lockfile.c: introduce 'hold_lock_file_for_update_mode' We use 'hold_lock_file_for_update' (and the '_timeout') variant to acquire a lock when updating references, the commit-graph file, and so on. In particular, the commit-graph machinery uses this to acquire a temporary file that is used to write a non-split commit-graph. In a subsequent commit, an issue in the commit-graph machinery produces graph files that have a different permission based on whether or not they are part of a multi-layer graph will be addressed. To do so, the commit-graph machinery will need a version of 'hold_lock_file_for_update' that takes the permission bits from the caller. Introduce such a function in this patch for both the 'hold_lock_file_for_update' and 'hold_lock_file_for_update_timeout' functions, and leave the existing functions alone by inlining their definitions in terms of the new mode variants. Note that, like in the previous commit, 'hold_lock_file_for_update_mode' is not guarenteed to set the given mode, since it may be modified by both the umask and 'core.sharedRepository'. Note also that even though the commit-graph machinery only calls 'hold_lock_file_for_update', that this is defined in terms of 'hold_lock_file_for_update_timeout', and so both need an additional mode parameter here. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano --- lockfile.c | 18 ++++++++++-------- lockfile.h | 32 ++++++++++++++++++++++++++++---- 2 files changed, 38 insertions(+), 12 deletions(-) diff --git a/lockfile.c b/lockfile.c index 8e8ab4f29f3..cc9a4b84283 100644 --- a/lockfile.c +++ b/lockfile.c @@ -70,7 +70,8 @@ static void resolve_symlink(struct strbuf *path) } /* Make sure errno contains a meaningful value on error */ -static int lock_file(struct lock_file *lk, const char *path, int flags) +static int lock_file(struct lock_file *lk, const char *path, int flags, + int mode) { struct strbuf filename = STRBUF_INIT; @@ -79,7 +80,7 @@ static int lock_file(struct lock_file *lk, const char *path, int flags) resolve_symlink(&filename); strbuf_addstr(&filename, LOCK_SUFFIX); - lk->tempfile = create_tempfile(filename.buf); + lk->tempfile = create_tempfile_mode(filename.buf, mode); strbuf_release(&filename); return lk->tempfile ? lk->tempfile->fd : -1; } @@ -99,7 +100,7 @@ static int lock_file(struct lock_file *lk, const char *path, int flags) * exactly once. If timeout_ms is -1, try indefinitely. */ static int lock_file_timeout(struct lock_file *lk, const char *path, - int flags, long timeout_ms) + int flags, long timeout_ms, int mode) { int n = 1; int multiplier = 1; @@ -107,7 +108,7 @@ static int lock_file_timeout(struct lock_file *lk, const char *path, static int random_initialized = 0; if (timeout_ms == 0) - return lock_file(lk, path, flags); + return lock_file(lk, path, flags, mode); if (!random_initialized) { srand((unsigned int)getpid()); @@ -121,7 +122,7 @@ static int lock_file_timeout(struct lock_file *lk, const char *path, long backoff_ms, wait_ms; int fd; - fd = lock_file(lk, path, flags); + fd = lock_file(lk, path, flags, mode); if (fd >= 0) return fd; /* success */ @@ -169,10 +170,11 @@ NORETURN void unable_to_lock_die(const char *path, int err) } /* This should return a meaningful errno on failure */ -int hold_lock_file_for_update_timeout(struct lock_file *lk, const char *path, - int flags, long timeout_ms) +int hold_lock_file_for_update_timeout_mode(struct lock_file *lk, + const char *path, int flags, + long timeout_ms, int mode) { - int fd = lock_file_timeout(lk, path, flags, timeout_ms); + int fd = lock_file_timeout(lk, path, flags, timeout_ms, mode); if (fd < 0) { if (flags & LOCK_DIE_ON_ERROR) unable_to_lock_die(path, errno); diff --git a/lockfile.h b/lockfile.h index 9843053ce89..db93e6ba73e 100644 --- a/lockfile.h +++ b/lockfile.h @@ -90,6 +90,15 @@ * functions. In particular, the state diagram and the cleanup * machinery are all implemented in the tempfile module. * + * Permission bits + * --------------- + * + * If you call either `hold_lock_file_for_update_mode` or + * `hold_lock_file_for_update_timeout_mode`, you can specify a suggested + * mode for the underlying temporary file. Note that the file isn't + * guaranteed to have this exact mode, since it may be limited by either + * the umask, 'core.sharedRepository', or both. See `adjust_shared_perm` + * for more. * * Error handling * -------------- @@ -156,12 +165,20 @@ struct lock_file { * file descriptor for writing to it, or -1 on error. If the file is * currently locked, retry with quadratic backoff for at least * timeout_ms milliseconds. If timeout_ms is 0, try exactly once; if - * timeout_ms is -1, retry indefinitely. The flags argument and error - * handling are described above. + * timeout_ms is -1, retry indefinitely. The flags argument, error + * handling, and mode are described above. */ -int hold_lock_file_for_update_timeout( +int hold_lock_file_for_update_timeout_mode( struct lock_file *lk, const char *path, - int flags, long timeout_ms); + int flags, long timeout_ms, int mode); + +static inline int hold_lock_file_for_update_timeout( + struct lock_file *lk, const char *path, + int flags, long timeout_ms) +{ + return hold_lock_file_for_update_timeout_mode(lk, path, flags, + timeout_ms, 0666); +} /* * Attempt to create a lockfile for the file at `path` and return a @@ -175,6 +192,13 @@ static inline int hold_lock_file_for_update( return hold_lock_file_for_update_timeout(lk, path, flags, 0); } +static inline int hold_lock_file_for_update_mode( + struct lock_file *lk, const char *path, + int flags, int mode) +{ + return hold_lock_file_for_update_timeout_mode(lk, path, flags, 0, mode); +} + /* * Return a nonzero value iff `lk` is currently locked. */