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[PATCH 2/3] lockfile.c: introduce 'hold_lock_file_for_update_mode'

From
Taylor Blau <me@ttaylorr.com>
Date
Apr 20, 2020, 22:51 UTC
Message-ID
<dad37d42334954d40f308a4fc3189a925f90df66.1587422630.git.me@ttaylorr.com>
In-Reply-To
<cover.1587422630.git.me@ttaylorr.com>

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 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 <me@ttaylorr.com>
---
 lockfile.c | 18 ++++++++++--------
 lockfile.h | 19 +++++++++++++++++--
 2 files changed, 27 insertions(+), 10 deletions(-)
diff --git a/lockfile.c b/lockfile.c
index 8e8ab4f29f..cc9a4b8428 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 9843053ce8..12f25279b5 100644
--- a/lockfile.h
+++ b/lockfile.h
@@ -159,9 +159,17 @@ struct lock_file {
  * timeout_ms is -1, retry indefinitely. The flags argument and error
  * handling 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 +183,13 @@ 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.
  */
-- 
2.26.1.108.gadb95c98e4
Previous: Junio C HamanoNext: Taylor Blau
Message 4 of 36 in “commit-graph: write non-split graphs as read-only”
  1. 0/3 commit-graph: write non-split graphs as read-onlyTaylor Blau, Apr 20, 2020
  2. 1/3 tempfile.c: introduce 'create_tempfile_mode'Taylor Blau, Apr 20, 2020
  3. Junio C HamanoApr 20, 2020
  4. 2/3 lockfile.c: introduce 'hold_lock_file_for_update_mode'Taylor Blau, Apr 20, 2020
  5. 3/3 commit-graph.c: write non-split graphs as read-onlyTaylor Blau, Apr 20, 2020
  6. Junio C HamanoApr 20, 2020
  7. Taylor BlauApr 20, 2020
  8. Junio C HamanoApr 21, 2020
  9. Jeff KingApr 21, 2020
  10. Junio C HamanoApr 21, 2020
  11. 0/4 commit-graph: write non-split graphs as read-onlyTaylor Blau, Apr 27, 2020
  12. 1/4 tempfile.c: introduce 'create_tempfile_mode'Taylor Blau, Apr 27, 2020
  13. 2/4 lockfile.c: introduce 'hold_lock_file_for_update_mode'Taylor Blau, Apr 27, 2020
  14. 3/4 commit-graph.c: write non-split graphs as read-onlyTaylor Blau, Apr 27, 2020
  15. Junio C HamanoApr 27, 2020
  16. Taylor BlauApr 27, 2020
  17. Junio C HamanoApr 28, 2020
  18. Jeff KingApr 28, 2020
  19. Junio C HamanoApr 28, 2020
  20. Jeff KingApr 28, 2020
  21. Junio C HamanoApr 28, 2020
  22. Jeff KingApr 28, 2020
  23. Taylor BlauApr 28, 2020
  24. Jeff KingApr 28, 2020
  25. Junio C HamanoApr 28, 2020
  26. Derrick StoleeApr 29, 2020
  27. 4/4 commit-graph.c: ensure graph layers respect core.sharedRepositoryTaylor Blau, Apr 27, 2020
  28. Taylor BlauApr 27, 2020
  29. Jeff KingApr 27, 2020
  30. 0/5 commit-graph: write non-split graphs as read-onlyTaylor Blau, Apr 29, 2020
  31. 1/5 tempfile.c: introduce 'create_tempfile_mode'Taylor Blau, Apr 29, 2020
  32. 2/5 lockfile.c: introduce 'hold_lock_file_for_update_mode'Taylor Blau, Apr 29, 2020
  33. 3/5 commit-graph.c: write non-split graphs as read-onlyTaylor Blau, Apr 29, 2020
  34. 4/5 commit-graph.c: ensure graph layers respect core.sharedRepositoryTaylor Blau, Apr 29, 2020
  35. 5/5 commit-graph.c: make 'commit-graph-chain's read-onlyTaylor Blau, Apr 29, 2020
  36. Jeff KingMay 1, 2020

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