2 files changed, 22 insertions, 1 deletions
diff --git a/src/common/log.c b/src/common/log.c
index 8fbb343a9..f8f80b909 100644
--- a/src/common/log.c
+++ b/src/common/log.c
@@ -29,6 +29,7 @@ typedef struct logfile_t {
   int max_loglevel; /**< Highest severity level to send to this stream. */
   int is_temporary; /**< Boolean: close after initializing logging subsystem.*/
   int is_syslog; /**< Boolean: send messages to syslog. */
+  log_callback callback; /**< If not num, send messages to this function. */
 } logfile_t;
 
 /** Helper: map a log severity to descriptive string. */
@@ -156,7 +157,7 @@ logv(int severity, const char *funcname, const char *format, va_list ap)
       lf = lf->next;
       continue;
     }
-    if (! (lf->file || lf->is_syslog)) {
+    if (! (lf->file || lf->is_syslog || lf->callback)) {
       lf = lf->next;
       continue;
     }
@@ -172,6 +173,10 @@ logv(int severity, const char *funcname, const char *format, va_list ap)
 #endif
       lf = lf->next;
       continue;
+    } else if (lf->callback) {
+      lf->callback(severity, end_of_prefix);
+      lf = lf->next;
+      continue;
     }
     if(fputs(buf, lf->file) == EOF ||
        fflush(lf->file) == EOF) { /* error */
@@ -300,6 +305,19 @@ void add_temp_log(void)
   logfiles->is_temporary = 1;
 }
 
+int add_callback_log(int loglevelMin, int loglevelMax, log_callback cb)
+{
+  logfile_t *lf;
+  lf = tor_malloc_zero(sizeof(logfile_t));
+  lf->loglevel = loglevelMin;
+  lf->max_loglevel = loglevelMax;
+  lf->filename = tor_strdup("callback>");
+  lf->callback = cb;
+  lf->next = logfiles;
+  logfiles = lf;
+  return 0;
+}
+
 /** Close any log handlers added by add_temp_log or marked by mark_logs_temp */
 void close_temp_logs(void)
 {
diff --git a/src/common/log.h b/src/common/log.h
index 55dabafaa..10e6c87dc 100644
--- a/src/common/log.h
+++ b/src/common/log.h
@@ -53,12 +53,15 @@
 #define LOG_ERR     3
 #endif
 
+typedef void (*log_callback)(int severity, const char *msg);
+
 int parse_log_level(const char *level);
 void add_stream_log(int severityMin, int severityMax, const char *name, FILE *stream);
 int add_file_log(int severityMin, int severityMax, const char *filename);
 #ifdef HAVE_SYSLOG_H
 int add_syslog_log(int loglevelMin, int loglevelMax);
 #endif
+int add_callback_log(int loglevelMin, int loglevelMax, log_callback cb);
 int get_min_log_level(void);
 void close_logs(void);
 void reset_logs(void);