From: Austin Clements Date: Sun, 9 Jun 2013 04:45:38 +0000 (-0400) Subject: emacs: Fix "no such file or directory" error X-Git-Tag: 0.16_rc1~59 X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=88cce8c6a4d898066c0ea4516352ab8749171654;p=notmuch.git emacs: Fix "no such file or directory" error Occasionally, when the user killed the search buffer when the CLI process was still running, Emacs would run the notmuch-start-notmuch-sentinel sentinel twice. The first call would process and delete the error output file and the second would fail with an "Opening input file: no such file or directory, ..." error when attempting to access the error file. Emacs isn't supposed to run the sentinel twice. The reason it does is rather subtle (and probably a bug in Emacs): 1) When the user kills the search buffer, Emacs invokes kill_buffer_processes, which sends a SIGHUP to notmuch, but doesn't do anything else. Meanwhile, suppose the notmuch search process has printed some more output, but Emacs hasn't consumed it yet (this is critical and is why this error only happens sometimes). 2) Emacs gets a SIGCHLD from the dying notmuch process, which invokes handle_child_signal, which sets the new process status, but can't do anything else because it's a signal handler. 3) Emacs returns to its idle loop, which calls status_notify, which sees that the notmuch process has a new status. This is where things get interesting. 3.1) Emacs guarantees that it will run process filters on any unconsumed output before running the process sentinel, so status_notify calls read_process_output, which consumes the final output and calls notmuch-search-process-filter. 3.1.1) notmuch-search-process-filter checks if the search buffer is still alive and, since it's not, it calls delete-process. 3.1.1.1) delete-process correctly sees that the process is already dead and doesn't try to send another signal, *but* it still modifies the status to "killed". To deal with the new status, it calls status_notify. Dun dun dun. We've seen this function before. 3.1.1.1.1) The *recursive* status_notify invocation sees that the process has a new status and doesn't have any more output to consume, so it invokes our sentinel and returns. 3.2) The outer status_notify call (which we're still in) is now done flushing pending process output, so it *also* invokes our sentinel. This patch addresses this problem at step 3.1.1, where the filter calls delete-process, since this is a strange and redundant thing to do anyway. --- diff --git a/emacs/notmuch.el b/emacs/notmuch.el index 7994d742..a9949a14 100644 --- a/emacs/notmuch.el +++ b/emacs/notmuch.el @@ -821,8 +821,7 @@ non-authors is found, assume that all of the authors match." (parse-buf (process-get proc 'parse-buf)) (inhibit-read-only t) done) - (if (not (buffer-live-p results-buf)) - (delete-process proc) + (when (buffer-live-p results-buf) (with-current-buffer parse-buf ;; Insert new data (save-excursion