[PATCH] fix syslog corruption when using customized name

[Chris Caputo]

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:

  log syslog name "bird-foo" all;

Per Linux SYSLOG(3):

  The argument ident in the call of openlog() is probably stored as-is.
  Thus, if the string it points to is changed, syslog() may start
  prepending the changed string, and if the string it points to ceases
  to exist, the results are undefined.  Most portable is to use a 
  string constant.

Signed-off-by: : Chris Caputo <ccaputo at alt.net>
---
 sysdep/unix/log.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/sysdep/unix/log.c b/sysdep/unix/log.c
index 1fd6442..7086f7d 100644
--- a/sysdep/unix/log.c
+++ b/sysdep/unix/log.c
@@ -289,17 +289,23 @@ 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);
+    }
 #endif
 }