Re: [PATCH] fix syslog corruption when using customized name

[Chris Caputo]

On Mon, 31 Oct 2016, Ondrej Zajicek wrote:
> On Sun, Oct 30, 2016 at 10:40:30PM +0000, Chris Caputo wrote:
> > Fix bug with syslog using string passed to openlog() which is later
> > stomped on, resulting in corrupted log messages. This happens when name
> > is specified in a syslog log line, ala:
> 
> Thanks, you are right. I will merge the patch.
> 
> Note that there is a minor bug in the patch as the current_syslog_name
> is not updated when new_syslog_name == NULL.

Ack - thank you for catching that.  Is this better?

Thanks,
Chris

diff --git a/sysdep/unix/log.c b/sysdep/unix/log.c
index 1fd6442..89eae01 100644
--- a/sysdep/unix/log.c
+++ b/sysdep/unix/log.c
@@ -289,17 +289,27 @@ log_switch(int debug, list *l, char *new_syslog_name)
 
 #ifdef HAVE_SYSLOG
   char *old_syslog_name = current_syslog_name;
-  current_syslog_name = new_syslog_name;
 
   if (old_syslog_name && new_syslog_name &&
       !strcmp(old_syslog_name, new_syslog_name))
     return;
 
   if (old_syslog_name)
-    closelog();
+    {
+      closelog();
+      free(old_syslog_name);
+    }
 
   if (new_syslog_name)
-    openlog(new_syslog_name, LOG_CONS | LOG_NDELAY, LOG_DAEMON);
+    {
+      current_syslog_name = xmalloc(strlen(new_syslog_name) + 1);
+      strcpy(current_syslog_name, new_syslog_name);
+      openlog(current_syslog_name, LOG_CONS | LOG_NDELAY, LOG_DAEMON);
+    }
+  else
+    {
+      current_syslog_name = NULL;
+    }
 #endif
 }