stderr plugin: Add `File' config option to log to a certain file.

Also make the actual log-action thread-safe.

diff --git a/src/stderr.c b/src/stderr.c
index 30e50d98fb3013f9440ad489af2317dc1cebb1c8..fed0a75ebc154bcb96598e077b7588e58fa83c9d 100644 (file)
--- a/src/stderr.c
+++ b/src/stderr.c
@@ -17,21 +17,29 @@
  *
  * Authors:
  *   Sebastian Harl <sh at tokkee.org>
+ *   Florian Forster <octo at verplant.org>
  **/
 
 #include "collectd.h"
 #include "common.h"
 #include "plugin.h"
 
+#include <pthread.h>
+
 #if COLLECT_DEBUG
 static int log_level = LOG_DEBUG;
 #else
 static int log_level = LOG_INFO;
 #endif /* COLLECT_DEBUG */
 
+static pthread_mutex_t file_lock = PTHREAD_MUTEX_INITIALIZER;
+
+static char *log_file = NULL;
+
 static const char *config_keys[] =
 {
-       "LogLevel"
+       "LogLevel",
+       "File"
 };
 static int config_keys_num = STATIC_ARRAY_SIZE (config_keys);
 
@@ -56,6 +64,19 @@ static int stderr_config (const char *key, const char *value)
                else
                        return 1;
        }
+       else if (0 == strcasecmp (key, "File")) {
+               sfree (log_file);
+
+               if (access (value, W_OK) == 0)
+                       log_file = strdup (value);
+               else {
+                       char errbuf[1024];
+                       /* We can't use `ERROR' yet.. */
+                       fprintf (stderr, "stderr plugin: Access to %s denied: %s\n",
+                                       value, sstrerror (errno, errbuf, sizeof (errbuf)));
+                       return 1;
+               }
+       }
        else {
                return -1;
        }
@@ -64,10 +85,40 @@ static int stderr_config (const char *key, const char *value)
 
 static void stderr_log (int severity, const char *msg)
 {
+       FILE *fh;
+       int do_close = 0;
+
        if (severity > log_level)
                return;
 
-       fprintf (stderr, "%s\n", msg);
+       pthread_mutex_lock (&file_lock);
+
+       if ((log_file == NULL) || (strcasecmp (log_file, "stderr") == 0))
+               fh = stderr;
+       else if (strcasecmp (log_file, "stdout") == 0)
+               fh = stdout;
+       else
+       {
+               fh = fopen (log_file, "a");
+               do_close = 1;
+       }
+
+       if (fh == NULL)
+       {
+                       char errbuf[1024];
+                       fprintf (stderr, "stderr plugin: fopen (%s) failed: %s\n",
+                                       (log_file == NULL) ? "<null>" : log_file,
+                                       sstrerror (errno, errbuf, sizeof (errbuf)));
+       }
+       else
+       {
+               fprintf (fh, "%s\n", msg);
+               if (do_close != 0)
+                       fclose (fh);
+       }
+
+       pthread_mutex_unlock (&file_lock);
+
        return;
 } /* void stderr_log (int, const char *) */