ph10 2005/03/29 16:19:25 BST
Modified files:
exim-doc/doc-txt ChangeLog
exim-src/src log.c
Log:
Test for failure of the fork() when a root process creates a log file.
Revision Changes Path
1.105 +9 -0 exim/exim-doc/doc-txt/ChangeLog
1.3 +12 -5 exim/exim-src/src/log.c
Index: ChangeLog
===================================================================
RCS file: /home/cvs/exim/exim-doc/doc-txt/ChangeLog,v
retrieving revision 1.104
retrieving revision 1.105
diff -u -r1.104 -r1.105
--- ChangeLog 29 Mar 2005 14:53:09 -0000 1.104
+++ ChangeLog 29 Mar 2005 15:19:25 -0000 1.105
@@ -1,4 +1,4 @@
-$Cambridge: exim/exim-doc/doc-txt/ChangeLog,v 1.104 2005/03/29 14:53:09 ph10 Exp $
+$Cambridge: exim/exim-doc/doc-txt/ChangeLog,v 1.105 2005/03/29 15:19:25 ph10 Exp $
Change log file for Exim from version 4.21
-------------------------------------------
@@ -98,6 +98,15 @@
PH/18 Installed Lars Mainka's patch for the support of CRL collections in
files or directories, for OpenSSL.
+
+PH/19 When an Exim process that is running as root has to create an Exim log
+ file, it does so in a subprocess that runs as exim:exim so as to get the
+ ownership right at creation (otherwise, other Exim processes might see
+ the file with the wrong ownership). There was no test for failure of this
+ fork() call, which would lead to the process getting stuck as it waited
+ for a non-existent subprocess. Forks do occasionally fail when resources
+ run out. I reviewed all the other calls to fork(); they all seem to check
+ for failure.
A note about Exim versions 4.44 and 4.50
Index: log.c
===================================================================
RCS file: /home/cvs/exim/exim-src/src/log.c,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- log.c 4 Jan 2005 10:00:42 -0000 1.2
+++ log.c 29 Mar 2005 15:19:25 -0000 1.3
@@ -1,4 +1,4 @@
-/* $Cambridge: exim/exim-src/src/log.c,v 1.2 2005/01/04 10:00:42 ph10 Exp $ */
+/* $Cambridge: exim/exim-src/src/log.c,v 1.3 2005/03/29 15:19:25 ph10 Exp $ */
/*************************************************
* Exim - an Internet mail transport agent *
@@ -321,8 +321,9 @@
/* Open was not successful: try creating the file. If this is a root process,
we must do the creating in a subprocess set to exim:exim in order to ensure
that the file is created with the right ownership. Otherwise, there can be a
-race if an exim process is trying to write to the log at the same time. The use
-of SIGUSR1 by the exiwhat utility can provoke a lot of simultaneous writing. */
+race if another Exim process is trying to write to the log at the same time.
+The use of SIGUSR1 by the exiwhat utility can provoke a lot of simultaneous
+writing. */
euid = geteuid();
@@ -350,10 +351,16 @@
_exit((create_log(buffer) < 0)? 1 : 0);
}
- /* Wait for the subprocess. If it succeeded retry the open. */
+ /* If we created a subprocess, wait for it. If it succeeded retry the open. */
- while (waitpid(pid, &status, 0) != pid);
- if (status == 0) *fd = Uopen(buffer, O_APPEND|O_WRONLY, LOG_MODE);
+ if (pid > 0)
+ {
+ while (waitpid(pid, &status, 0) != pid);
+ if (status == 0) *fd = Uopen(buffer, O_APPEND|O_WRONLY, LOG_MODE);
+ }
+
+ /* If we failed to create a subprocess, we are in a bad way. We fall through
+ with *fd still < 0, and errno set, letting the code below handle the error. */
}
/* If we now have an open file, set the close-on-exec flag and return. */
