Merge pull request #1667 from amitelka/feature/opt_statsfile_update_interval

Added env variable to allow custom interval update of fuzzer_stats file

docs/env_variables.md

@@ -584,6 +584,12 @@ checks or alter some of the more exotic semantics of the tool:
   - Set `AFL_PIZZA_MODE` to 1 to enable the April 1st stats menu, set to 0
     to disable although it is 1st of April.
 
+  - If you need a specific interval to update fuzzer_stats file, you can
+    set `AFL_FUZZER_STATS_UPDATE_INTERVAL` to the interval in seconds you'd
+    the file to be updated.
+    Note that will not be exact and with slow targets it can take seconds
+    until there is a slice for the time test.
+
 ## 5) Settings for afl-qemu-trace
 
 The QEMU wrapper used to instrument binary-only code supports several settings:

include/afl-fuzz.h

@@ -693,6 +693,7 @@ typedef struct afl_state {
 
   /* statistics file */
   double last_bitmap_cvg, last_stability, last_eps;
+  u64    stats_file_update_freq_msecs;  /* Stats update frequency (msecs)   */
 
   /* plot file saves from last run */
   u32 plot_prev_qp, plot_prev_pf, plot_prev_pnf, plot_prev_ce, plot_prev_md;

include/envs.h

@@ -91,6 +91,7 @@ static char *afl_environment_variables[] = {
     "AFL_FRIDA_TRACEABLE",
     "AFL_FRIDA_VERBOSE",
     "AFL_FUZZER_ARGS",  // oss-fuzz
+    "AFL_FUZZER_STATS_UPDATE_INTERVAL",
     "AFL_GDB",
     "AFL_GCC_ALLOWLIST",
     "AFL_GCC_DENYLIST",

src/afl-fuzz-state.c

@@ -24,6 +24,7 @@
  */
 
 #include <signal.h>
+#include <limits.h>
 #include "afl-fuzz.h"
 #include "envs.h"
 
@@ -100,6 +101,7 @@ void afl_state_init(afl_state_t *afl, uint32_t map_size) {
   afl->hang_tmout = EXEC_TIMEOUT;
   afl->exit_on_time = 0;
   afl->stats_update_freq = 1;
+  afl->stats_file_update_freq_msecs = STATS_UPDATE_SEC * 1000;
   afl->stats_avg_exec = 0;
   afl->skip_deterministic = 1;
   afl->sync_time = SYNC_TIME;
@@ -565,6 +567,26 @@ void read_afl_environment(afl_state_t *afl, char **envp) {
 
             }
 
+          } else if (!strncmp(env, "AFL_FUZZER_STATS_UPDATE_INTERVAL",
+
+                              afl_environment_variable_len)) {
+
+            u64 stats_update_freq_sec =
+                strtoull(get_afl_env(afl_environment_variables[i]), NULL, 0);
+            if (stats_update_freq_sec >= UINT_MAX ||
+                0 == stats_update_freq_sec) {
+
+              WARNF(
+                  "Incorrect value given to AFL_FUZZER_STATS_UPDATE_INTERVAL, "
+                  "using default of %d seconds\n",
+                  STATS_UPDATE_SEC);
+
+            } else {
+
+              afl->stats_file_update_freq_msecs = stats_update_freq_sec * 1000;
+
+            }
+
           }
 
         } else {

src/afl-fuzz-stats.c

@@ -611,9 +611,10 @@ void show_stats_normal(afl_state_t *afl) {
 
   /* Roughly every minute, update fuzzer stats and save auto tokens. */
 
-  if (unlikely(!afl->non_instrumented_mode &&
-               (afl->force_ui_update ||
-                cur_ms - afl->stats_last_stats_ms > STATS_UPDATE_SEC * 1000))) {
+  if (unlikely(
+          !afl->non_instrumented_mode &&
+          (afl->force_ui_update || cur_ms - afl->stats_last_stats_ms >
+                                       afl->stats_file_update_freq_msecs))) {
 
     afl->stats_last_stats_ms = cur_ms;
     write_stats_file(afl, t_bytes, t_byte_ratio, stab_ratio,

src/afl-fuzz.c

@@ -210,7 +210,8 @@ static void usage(u8 *argv0, int more_help) {
       "  -b cpu_id     - bind the fuzzing process to the specified CPU core "
       "(0-...)\n"
       "  -e ext        - file extension for the fuzz test input file (if "
-      "needed)\n\n",
+      "needed)\n"
+      "\n",
       argv0, EXEC_TIMEOUT, MEM_LIMIT, MAX_FILE, FOREIGN_SYNCS_MAX);
 
   if (more_help > 1) {
@@ -312,6 +313,8 @@ static void usage(u8 *argv0, int more_help) {
       "                      afl-clang-lto/afl-gcc-fast target\n"
       "AFL_PERSISTENT: enforce persistent mode (if __AFL_LOOP is in a shared lib\n"
       "AFL_DEFER_FORKSRV: enforced deferred forkserver (__AFL_INIT is in a .so)\n"
+      "AFL_FUZZER_STATS_UPDATE_INTERVAL: interval to update fuzzer_stats file in seconds, "
+      "(default: 60, minimum: 1)\n"
       "\n"
     );