zcip: make it work on NOMMU (+ improve NOMMU support machinery)

fsck: fix bad English in a comment

2 files changed, 16 insertions, 6 deletions

diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index 89ae9a73c..ec8b9b1d7 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -40,11 +40,14 @@ pid_t spawn(char **argv)
 		 * (but don't run atexit() stuff, which would screw up parent.)
 		 */
 		failed = errno;
-		_exit(0);
+		_exit(111);
 	}
 	/* parent */
-	/* Unfortunately, this is not reliable: vfork()
-	 * can be equivalent to fork() according to standards */
+	/* Unfortunately, this is not reliable: according to standards
+	 * vfork() can be equivalent to fork() and we won't see value
+	 * of 'failed'.
+	 * Interested party can wait on pid and learn exit code.
+	 * If 111 - then it (most probably) failed to exec */
 	if (failed) {
 		errno = failed;
 		return -1;
diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index 14bd62a15..7f870ac8b 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -192,9 +192,16 @@ int wait4pid(int pid)
 {
 	int status;
 
-	if (pid == -1 || waitpid(pid, &status, 0) == -1) return -1;
-	if (WIFEXITED(status)) return WEXITSTATUS(status);
-	if (WIFSIGNALED(status)) return WTERMSIG(status);
+	if (pid <= 0) {
+		errno = ECHILD;
+		return -1;
+	}
+	if (waitpid(pid, &status, 0) == -1)
+		return -1;
+	if (WIFEXITED(status))
+		return WEXITSTATUS(status);
+	if (WIFSIGNALED(status))
+		return WTERMSIG(status) + 10000;
 	return 0;
 }