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;
 }