GNU bug report logs - #8303
Emacs daemon initialization should not ignore I/O errors

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Paul Eggert <eggert <at> cs.ucla.edu>
Subject: bug#8303: closed (fix merged to trunk)
Date: Wed, 23 Mar 2011 22:07:11 +0000

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Your bug report

#8303: Emacs daemon initialization should not ignore I/O errors

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 8303 <at> debbugs.gnu.org.

-- 
8303: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8303
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

[Message part 2 (message/rfc822, inline)]

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: 8310-done <at> debbugs.gnu.org, 8318-done <at> debbugs.gnu.org, 
	8306-done <at> debbugs.gnu.org, 8303-done <at> debbugs.gnu.org, 
	8277-done <at> debbugs.gnu.org, 8298-done <at> debbugs.gnu.org, 
	8290-done <at> debbugs.gnu.org, 8278-done <at> debbugs.gnu.org
Subject: fix merged to trunk
Date: Wed, 23 Mar 2011 15:06:46 -0700

I committed a fix to the trunk for this,
as part of a recent merge (bzr 103721).

[Message part 3 (message/rfc822, inline)]

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: bug-gnu-emacs <at> gnu.org
Subject: Emacs daemon initialization should not ignore I/O errors
Date: Sun, 20 Mar 2011 16:34:22 -0700

Severity: minor

daemon-initialized currently ignores I/O errors when setting
up the daemon, but it should report them, on the off chance that
system resources are low so that (for example) one cannot open
/dev/null or dup a file descriptor.  I plan to install the following
patch in the trunk, to address this.

2011-03-20  Paul Eggert  <eggert <at> cs.ucla.edu>

	* emacs.c (Fdaemon_initialized): Do not ignore I/O errors.

--- src/emacs.c	2011-03-17 16:32:03 +0000
+++ src/emacs.c	2011-03-20 21:03:44 +0000
@@ -2312,6 +2312,7 @@
   (void)
 {
   int nfd;
+  int err = 0;
 
   if (!IS_DAEMON)
     error ("This function can only be called if emacs is run as a daemon");
@@ -2324,10 +2325,11 @@
 
   /* Get rid of stdin, stdout and stderr.  */
   nfd = open ("/dev/null", O_RDWR);
-  dup2 (nfd, 0);
-  dup2 (nfd, 1);
-  dup2 (nfd, 2);
-  close (nfd);
+  err |= nfd < 0;
+  err |= dup2 (nfd, 0) < 0;
+  err |= dup2 (nfd, 1) < 0;
+  err |= dup2 (nfd, 2) < 0;
+  err |= close (nfd) != 0;
 
   /* Closing the pipe will notify the parent that it can exit.
      FIXME: In case some other process inherited the pipe, closing it here
@@ -2336,10 +2338,13 @@
      Instead, we should probably close the pipe in start-process and
      call-process to make sure the pipe is never inherited by
      subprocesses.  */
-  write (daemon_pipe[1], "\n", 1);
-  close (daemon_pipe[1]);
+  err |= write (daemon_pipe[1], "\n", 1) < 0;
+  err |= close (daemon_pipe[1]) != 0;
   /* Set it to an invalid value so we know we've already run this function.  */
   daemon_pipe[1] = -1;
+
+  if (err)
+    error ("I/O error during daemon initialization");
   return Qt;
 }
 

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