[PATCH 09/22] api-lockfile: expand the documentation

[Michael Haggerty <mhagger@alum.mit.edu>]

Document a couple more functions and the flags argument as used by
hold_lock_file_for_update() and hold_lock_file_for_append().

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 Documentation/technical/api-lockfile.txt | 36 +++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/Documentation/technical/api-lockfile.txt b/Documentation/technical/api-lockfile.txt
index dd89404..95ed03b 100644
--- a/Documentation/technical/api-lockfile.txt
+++ b/Documentation/technical/api-lockfile.txt
@@ -28,9 +28,39 @@ hold_lock_file_for_update::
 	the final destination (e.g. `$GIT_DIR/index`) and a flag
 	`die_on_error`.  Attempt to create a lockfile for the
 	destination and return the file descriptor for writing
-	to the file.  If `die_on_error` flag is true, it dies if
-	a lock is already taken for the file; otherwise it
-	returns a negative integer to the caller on failure.
+	to the file.  The flags parameter is a combination of
++
+--
+LOCK_NODEREF::
+
+	Usually symbolic links in path are resolved in path and the
+	lockfile is created by adding ".lock" to the resolved path;
+	however, if `LOCK_NODEREF` is set, then the lockfile is
+	created by adding ".lock" to the path argument itself.
+
+LOCK_DIE_ON_ERROR::
+
+	If a lock is already taken for the file, `die()` with an error
+	message.  If this option is not specified, return a negative
+	integer to the caller on failure.
+--
+
+hold_lock_file_for_append::
+
+	Like `hold_lock_file_for_update()`, except that additionally
+	the existing contents of the file (if any) are copied to the
+	lockfile and its write pointer is positioned at the end of the
+	file before returning.
+
+unable_to_lock_error::
+
+	Emit an error describing that there was an error locking the
+	specified path.  The err parameter should be the errno of the
+	problem that caused the failure.
+
+unable_to_lock_index_die::
+
+	Like `unable_to_lock_error()`, but also `die()`.
 
 commit_lock_file::
 
-- 
1.9.0