From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Barkalow Subject: [PATCH 2/8] Add a lockfile function to append to a file Date: Thu, 17 Apr 2008 20:02:31 -0400 (EDT) Message-ID: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: git@vger.kernel.org, Johannes Schindelin To: Junio C Hamano X-From: git-owner@vger.kernel.org Fri Apr 18 02:03:31 2008 connect(): Connection refused Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1Jme4f-0003DR-Qt for gcvg-git-2@gmane.org; Fri, 18 Apr 2008 02:03:30 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755494AbYDRACi (ORCPT ); Thu, 17 Apr 2008 20:02:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755493AbYDRACi (ORCPT ); Thu, 17 Apr 2008 20:02:38 -0400 Received: from iabervon.org ([66.92.72.58]:49927 "EHLO iabervon.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755462AbYDRACh (ORCPT ); Thu, 17 Apr 2008 20:02:37 -0400 Received: (qmail 7367 invoked by uid 1000); 18 Apr 2008 00:02:31 -0000 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 18 Apr 2008 00:02:31 -0000 User-Agent: Alpine 1.00 (LNX 882 2007-12-20) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: This takes care of copying the original contents into the replacement file after the lock is held, so that concurrent additions can't miss each other's changes. Signed-off-by: Daniel Barkalow --- How about this? Also doesn't leak a fd and catches trying to append to a file you can't read. Should I worry about mmap failing after the open? cache.h | 1 + lockfile.c | 23 +++++++++++++++++++++++ 2 files changed, 24 insertions(+), 0 deletions(-) diff --git a/cache.h b/cache.h index 50b28fa..8d066bf 100644 --- a/cache.h +++ b/cache.h @@ -391,6 +391,7 @@ struct lock_file { char filename[PATH_MAX]; }; 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 hold_locked_index(struct lock_file *, int); diff --git a/lockfile.c b/lockfile.c index 663f18f..f1b5416 100644 --- a/lockfile.c +++ b/lockfile.c @@ -160,6 +160,29 @@ int hold_lock_file_for_update(struct lock_file *lk, const char *path, int die_on return fd; } +int hold_lock_file_for_append(struct lock_file *lk, const char *path, int die_on_error) +{ + int fd = lock_file(lk, path); + struct stat st; + if (fd < 0) { + if (die_on_error) + die("unable to create '%s.lock': %s", + path, strerror(errno)); + } else if (!stat(path, &st)) { + int orig_fd = open(path, O_RDONLY); + size_t mmap_size = xsize_t(st.st_size); + void *mmap; + if (orig_fd < 0) + die("unable to read %s to append to it", path); + mmap = xmmap(NULL, mmap_size, PROT_READ, MAP_PRIVATE, + orig_fd, 0); + write_or_die(fd, mmap, mmap_size); + munmap(mmap, mmap_size); + close(orig_fd); + } + return fd; +} + int close_lock_file(struct lock_file *lk) { int fd = lk->fd; -- 1.5.4.3.610.gea6cd