lockfile: allow reopening a closed but still locked file

In some code paths (e.g. giving "add -i" to prepare the contents to
be committed interactively inside "commit -p") where a caller takes
a lock, writes the new content, give chance for others to use it
while still holding the lock, and then releases the lock when all is
done.  As an extension, allow the caller to re-update an already
closed file while still holding the lock (i.e. not yet committed) by
re-opening the file, to be followed by updating the contents and
then by the usual close_lock_file() or commit_lock_file().

This is necessary if we want to add code to rebuild the cache-tree
and write the resulting index out after "add -i" returns the control
to "commit -p", for example.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/cache.h b/cache.h
index c6b7770f60746b4b7259d495da8b8ccc5df9bdfc..b780794d6c7870146abd1ce2e28b71355c64a198 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -567,6 +567,7 @@ extern NORETURN void unable_to_lock_index_die(const char *path, int err);
 extern int hold_lock_file_for_update(struct lock_file *, const char *path, int);
 extern int hold_lock_file_for_append(struct lock_file *, const char *path, int);
 extern int commit_lock_file(struct lock_file *);
+extern int reopen_lock_file(struct lock_file *);
 extern void update_index_if_able(struct index_state *, struct lock_file *);
 
 extern int hold_locked_index(struct lock_file *, int);

diff --git a/lockfile.c b/lockfile.c
index b7066143494bcfa3e629dd718daf8959af6c4b86..9c12ec5ca6da8af4384676cc7893d6eec57c9fcf 100644 (file)
--- a/lockfile.c
+++ b/lockfile.c
@@ -228,6 +228,16 @@ int close_lock_file(struct lock_file *lk)
        return close(fd);
 }
 
+int reopen_lock_file(struct lock_file *lk)
+{
+       if (0 <= lk->fd)
+               die(_("BUG: reopen a lockfile that is still open"));
+       if (!lk->filename[0])
+               die(_("BUG: reopen a lockfile that has been committed"));
+       lk->fd = open(lk->filename, O_WRONLY);
+       return lk->fd;
+}
+
 int commit_lock_file(struct lock_file *lk)
 {
        char result_file[PATH_MAX];