Yoann brought the following issue to my attention, which affects libev ev_stat watchers when a file gets deleted which is still open.
----- Forwarded message from Yoann Vandoorselaere <[EMAIL PROTECTED]> ----- Subject: libev issue due to inotify bug From: Yoann Vandoorselaere <[EMAIL PROTECTED]> Date: Mon, 13 Oct 2008 17:25:51 +0200 To: [EMAIL PROTECTED] X-Mailer: Evolution 2.22.3.1 Hello Marc, We are currently porting Prelude-LML (a log analyzer) to use libev ev_stat notification in place of GAMIN/basic polling, and wanted to let you know about an inotify bug that impact vanilla Linux kernel < 2.6.25. Before 2.6.25, inotify did not notify the user in case a file st_nlink reached 0 (IN_ATTRIB event). This is problematic for application that wish to be notified of file deletion although they still have an open file descriptor on the deleted file (they never get any notification about the deletion). More information about the kernel issue is available here: http://www.ussg.indiana.edu/hypermail/linux/kernel/0711.3/1208.html It would be great to add some test case to libev.m4 so that it check whether the current inotify version is buggy or not (some Linux distribution use kernel < 2.6.25 but included a patch for this issue). You can test the problem using the following code: static void libev_check_cb(struct ev_loop *loop, ev_stat *st, int revents) { int *inotify_work = st->data; *inotify_work = TRUE; } static void libev_check_timer_cb(struct ev_loop *loop, ev_stat *st, int revents) { ev_unloop(EV_A_ EVUNLOOP_ALL); } static void inotify_ok(void) { int fd; char fname[1024]; struct ev_stat event; struct ev_timer evt; int inotify_ok = FALSE; snprintf(fname, sizeof(fname), "%s/test-inotify.XXXXXX", P_tmpdir); fd = mkstemp(fname); if ( fd < 0 ) { fprintf(stderr, "error creating unique temporary filename: %s.\n", strerror(errno)); return; } ev_timer_init(&evt, libev_check_timer_cb, 1, 1); evt.data = &inotify_ok; ev_timer_start(ev_default_loop(0), &evt); ev_stat_init(&event, libev_check_cb, fname, 1); event.data = &inotify_ok; ev_stat_start(ev_default_loop(0), &event); unlink(fname); ev_loop(ev_default_loop(0), 0); if ( ! inotify_ok ) { fprintf(stderr, "WARNING: buggy delete detection.\n"); } close(fd); } Hope this help, Regards, -- Yoann Vandoorselaere <[EMAIL PROTECTED]> ----- End forwarded message ----- -- The choice of a Deliantra, the free code+content MORPG -----==- _GNU_ http://www.deliantra.net ----==-- _ generation ---==---(_)__ __ ____ __ Marc Lehmann --==---/ / _ \/ // /\ \/ / [EMAIL PROTECTED] -=====/_/_//_/\_,_/ /_/\_\ _______________________________________________ libev mailing list libev@lists.schmorp.de http://lists.schmorp.de/cgi-bin/mailman/listinfo/libev
