minimum sync time

docs/Changelog.md

@@ -35,6 +35,7 @@ sending a mail to <afl-users+subscribe@googlegroups.com>.
     - fixed a few crashes
     - switched to an even faster RNG
     - added hghwng's patch for faster trace map analysis
+    - added minimum SYNC_TIME to include/config.h (30 minutes default)
   - afl-cc
     - allow instrumenting LLVMFuzzerTestOneInput
     - fixed endless loop for allow/blocklist lines starting with a

include/afl-fuzz.h

@@ -570,6 +570,7 @@ typedef struct afl_state {
       blocks_eff_total,                 /* Blocks subject to effector maps  */
       blocks_eff_select,                /* Blocks selected as fuzzable      */
       start_time,                       /* Unix start time (ms)             */
+      last_sync_time,			/* Time of last sync                */
       last_path_time,                   /* Time for most recent path (ms)   */
       last_crash_time,                  /* Time for most recent crash (ms)  */
       last_hang_time;                   /* Time for most recent hang (ms)   */

include/config.h

@@ -280,6 +280,11 @@
 
 #define SYNC_INTERVAL 8
 
+/* Sync time (minimum time between syncing in ms, time is halfed for -M main
+   nodes): */
+
+#define SYNC_TIME 18000000LLU  /* 18000000 = 30 minutes */
+
 /* Output directory reuse grace period (minutes): */
 
 #define OUTPUT_GRACE 25

src/afl-fuzz-run.c

@@ -707,6 +707,8 @@ void sync_fuzzers(afl_state_t *afl) {
 
   if (afl->foreign_sync_cnt) read_foreign_testcases(afl, 0);
 
+  afl->last_sync_time = get_cur_time();
+
 }
 
 /* Trim all new test cases to save cycles when doing deterministic checks. The

src/afl-fuzz.c

@@ -1986,18 +1986,27 @@ int main(int argc, char **argv_orig, char **envp) {
 
         if (unlikely(afl->is_main_node)) {
 
+          if (unlikely(get_cur_time() >
+                       (SYNC_TIME >> 1) + afl->last_sync_time)) {
+
             if (!(sync_interval_cnt++ % (SYNC_INTERVAL / 3))) {
 
               sync_fuzzers(afl);
 
             }
 
+          }
+
         } else {
 
+          if (unlikely(get_cur_time() > SYNC_TIME + afl->last_sync_time)) {
+
             if (!(sync_interval_cnt++ % SYNC_INTERVAL)) { sync_fuzzers(afl); }
 
           }
 
+        }
+
       } else {
 
         sync_fuzzers(afl);