rework exitcodes

* add 128 to exitcode if child receives a fatal signal
(this is similar to what bash and other shells do)
* unify exitcodes across firejail: treat join'ed processes
the same as processes in the primary process tree

src/firejail/join.c

@@ -536,7 +536,6 @@ void join(pid_t pid, int argc, char **argv, int index) {
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
 
 #ifdef HAVE_APPARMOR
- // add apparmor confinement after the execve
  set_apparmor();
 #endif
 
@@ -601,9 +600,9 @@ void join(pid_t pid, int argc, char **argv, int index) {
  if (WIFEXITED(status)) {
  status = WEXITSTATUS(status);
  } else if (WIFSIGNALED(status)) {
- status = WTERMSIG(status);
+ status = 128 + WTERMSIG(status);
  } else {
- status = 0;
+ status = -1;
  }
 
  exit(status);

src/firejail/main.c

@@ -3216,10 +3216,10 @@ printf("link #%s#\n", prf->link);
  if (WIFEXITED(status)){
  myexit(WEXITSTATUS(status));
  } else if (WIFSIGNALED(status)) {
- myexit(WTERMSIG(status));
+ myexit(128 + WTERMSIG(status));
  } else {
- myexit(0);
+ myexit(1);
  }
 
- return 0;
+ return 1;
 }

src/firejail/sandbox.c

@@ -1243,7 +1243,6 @@ int sandbox(void* sandbox_arg) {
 
  if (app_pid == 0) {
 #ifdef HAVE_APPARMOR
- // add apparmor confinement after the execve
  set_apparmor();
 #endif
 
@@ -1262,9 +1261,13 @@ int sandbox(void* sandbox_arg) {
 
  if (WIFEXITED(status)) {
  // if we had a proper exit, return that exit status
- return WEXITSTATUS(status);
+ status = WEXITSTATUS(status);
+ } else if (WIFSIGNALED(status)) {
+ // distinguish fatal signals by adding 128
+ status = 128 + WTERMSIG(status);
  } else {
- // something else went wrong!
- return -1;
+ status = -1;
  }
+
+ return status;
 }