Log: Fix broken syslog name

BIRD passed string from configuration to openlog(), which kept it
internally. After reconfiguration the old string was freed, therefore
openlog had invalid copy.

Thanks to Chris Caputo for the original patch.

2 files changed, 20 insertions, 7 deletions

diff --git a/lib/string.h b/lib/string.h
index 9af49b9e..bf0b7cb0 100644
--- a/lib/string.h
+++ b/lib/string.h
@@ -30,6 +30,15 @@ static inline char *xbasename(const char *str)
   return s ? s+1 : (char *) str;
 }
 
+static inline char *
+xstrdup(const char *c)
+{
+  size_t l = strlen(c) + 1;
+  char *z = xmalloc(l);
+  memcpy(z, c, l);
+  return z;
+}
+
 #define ROUTER_ID_64_LENGTH 23
 
 #endif
diff --git a/sysdep/unix/log.c b/sysdep/unix/log.c
index 1fd64426..b89e6b7a 100644
--- a/sysdep/unix/log.c
+++ b/sysdep/unix/log.c
@@ -288,18 +288,22 @@ log_switch(int debug, list *l, char *new_syslog_name)
   current_log_list = l;
 
 #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))
+  if (current_syslog_name && new_syslog_name &&
+      !strcmp(current_syslog_name, new_syslog_name))
     return;
 
-  if (old_syslog_name)
+  if (current_syslog_name)
+  {
     closelog();
+    xfree(current_syslog_name);
+    current_syslog_name = NULL;
+  }
 
   if (new_syslog_name)
-    openlog(new_syslog_name, LOG_CONS | LOG_NDELAY, LOG_DAEMON);
+  {
+    current_syslog_name = xstrdup(new_syslog_name);
+    openlog(current_syslog_name, LOG_CONS | LOG_NDELAY, LOG_DAEMON);
+  }
 #endif
 }