merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 28 insertions, 4 deletions

diff --git a/third_party/git/lockfile.h b/third_party/git/lockfile.h
index 9843053ce8..db93e6ba73 100644
--- a/third_party/git/lockfile.h
+++ b/third_party/git/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 mode);
+
+static inline int hold_lock_file_for_update_timeout(
 		struct lock_file *lk, const char *path,
-		int flags, long timeout_ms);
+		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.
  */