User defined kill signal value (#678)

* Adding AFL_KILL_SIGNAL environment variable

Controlling the kill signal used to end forked processes.

* Checking validity of AFL_KILL_SIGNAL env variable

This commit also sets a valid value in the environment to avoid
duplicating code in at_exit(). Changing data type of
fsrv->kill_signal to u8 to match last_kill_signal.

* Adding afl_kill_signal to AFL (environment) state

This commit simply introduces a struct member for future use. The
env variable is not used from the afl struct but from fsrv, where
its validity is checked, resulting in a FATAL in case of errors.

1 files changed, 2 insertions, 0 deletions

diff --git a/include/forkserver.h b/include/forkserver.h
index 8e029266..3019e289 100644
--- a/include/forkserver.h
+++ b/include/forkserver.h
@@ -99,6 +99,8 @@ typedef struct afl_forkserver {
 
   void (*add_extra_func)(void *afl_ptr, u8 *mem, u32 len);
 
+  u8 kill_signal;
+
 } afl_forkserver_t;
 
 typedef enum fsrv_run_result {