Option for specifying forkserver initialization timeout via environment variable (#522)

* Addition of AFL_FORKSRV_INIT_TMOUT env var

This commit introduces a new environment variable which allows to
specify the timespan AFL should wait for initial contact with the
forkserver.

This is useful for fuzz-targets requiring a rather long setup time
before the actual fuzzing can be started (e.g., unicorn).

* add .swp files to .gitignore

* Inherit init_tmout in afl_fsrv_init_dup

Without this patch, the forkserver would spawn with a timeout of 0 in
cmplog mode, leading to an immediate crash.

Additionally, this commit removes a spurious whitespace.

* Initialize afl->fsrv.init_tmout in afl_fsrv_init

Not all afl-components will need the new AFL_FORKSRV_INIT_TMOUT
environment variable. Hence, it's initialized to the safe "default"
value from before in afl_fsrv_init now.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/afl-forkserver.c b/src/afl-forkserver.c
index 9d9e81cd..51734579 100644
--- a/src/afl-forkserver.c
+++ b/src/afl-forkserver.c
@@ -79,6 +79,7 @@ void afl_fsrv_init(afl_forkserver_t *fsrv) {
   fsrv->use_stdin = 1;
   fsrv->no_unlink = 0;
   fsrv->exec_tmout = EXEC_TIMEOUT;
+  fsrv->init_tmout = EXEC_TIMEOUT * FORK_WAIT_MULT;
   fsrv->mem_limit = MEM_LIMIT;
   fsrv->out_file = NULL;
 
@@ -101,6 +102,7 @@ void afl_fsrv_init_dup(afl_forkserver_t *fsrv_to, afl_forkserver_t *from) {
   fsrv_to->out_fd = from->out_fd;
   fsrv_to->dev_null_fd = from->dev_null_fd;
   fsrv_to->exec_tmout = from->exec_tmout;
+  fsrv_to->init_tmout = from->init_tmout;
   fsrv_to->mem_limit = from->mem_limit;
   fsrv_to->map_size = from->map_size;
   fsrv_to->support_shmem_fuzz = from->support_shmem_fuzz;
@@ -519,13 +521,13 @@ void afl_fsrv_start(afl_forkserver_t *fsrv, char **argv,
 
     u32 time_ms =
         read_s32_timed(fsrv->fsrv_st_fd, &status,
-                       fsrv->exec_tmout * FORK_WAIT_MULT, stop_soon_p);
+                       fsrv->init_tmout, stop_soon_p);
 
     if (!time_ms) {
 
       kill(fsrv->fsrv_pid, SIGKILL);
 
-    } else if (time_ms > fsrv->exec_tmout * FORK_WAIT_MULT) {
+    } else if (time_ms > fsrv->init_tmout) {
 
       fsrv->last_run_timed_out = 1;
       kill(fsrv->fsrv_pid, SIGKILL);