*: code shrink and better "died from signal" reporting from wait4pid

function                                             old     new   delta
parse                                                964     967      +3
udhcp_run_script                                     670     665      -5
singlemount                                          911     906      -5
mount_it_now                                         360     355      -5
inotifyd_main                                        521     516      -5
xspawn                                                21       -     -21
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/4 up/down: 3/-41)             Total: -38 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

debianutils/run_parts.c

@@ -159,14 +159,14 @@ int run_parts_main(int argc UNUSED_PARAM, char **argv)
 			continue;
 		}
 		cmd[0] = name;
-		ret = wait4pid(spawn(cmd));
+		ret = spawn_and_wait(cmd);
 		if (ret == 0)
 			continue;
 		n = 1;
 		if (ret < 0)
 			bb_perror_msg("can't execute '%s'", name);
 		else /* ret > 0 */
-			bb_error_msg("%s exited with code %d", name, ret);
+			bb_error_msg("%s exited with code %d", name, ret & 0xff);
 	}
 
 	return n;

findutils/xargs.c

@@ -64,16 +64,9 @@ static int xargs_exec(char **args)
 		bb_error_msg("%s: exited with status 255; aborting", args[0]);
 		return 124;
 	}
-/* Huh? I think we won't see this, ever. We don't wait with WUNTRACED!
-	if (WIFSTOPPED(status)) {
-		bb_error_msg("%s: stopped by signal %d",
-			args[0], WSTOPSIG(status));
-		return 125;
-	}
-*/
-	if (status >= 1000) {
+	if (status >= 0x180) {
 		bb_error_msg("%s: terminated by signal %d",
-			args[0], status - 1000);
+			args[0], status - 0x180);
 		return 125;
 	}
 	if (status)

include/libbb.h

@@ -812,21 +812,22 @@ int bb_execvp(const char *file, char *const argv[]) FAST_FUNC;
 #define BB_EXECLP(prog,cmd,...) execlp(prog,cmd, __VA_ARGS__)
 #endif
 
-/* NOMMU friendy fork+exec */
+/* NOMMU friendy fork+exec: */
 pid_t spawn(char **argv) FAST_FUNC;
 pid_t xspawn(char **argv) FAST_FUNC;
 
 pid_t safe_waitpid(pid_t pid, int *wstat, int options) FAST_FUNC;
-/* Unlike waitpid, waits ONLY for one process.
+pid_t wait_any_nohang(int *wstat) FAST_FUNC;
+/* wait4pid: unlike waitpid, waits ONLY for one process.
+ * Returns sig + 0x180 if child is killed by signal.
  * It's safe to pass negative 'pids' from failed [v]fork -
  * wait4pid will return -1 (and will not clobber [v]fork's errno).
  * IOW: rc = wait4pid(spawn(argv));
  *      if (rc < 0) bb_perror_msg("%s", argv[0]);
- *      if (rc > 0) bb_error_msg("exit code: %d", rc);
+ *      if (rc > 0) bb_error_msg("exit code: %d", rc & 0xff);
  */
 int wait4pid(pid_t pid) FAST_FUNC;
-pid_t wait_any_nohang(int *wstat) FAST_FUNC;
-/* wait4pid(spawn(argv)) + NOFORK/NOEXEC (if configured) */
+/* Same as wait4pid(spawn(argv)), but with NOFORK/NOEXEC if configured: */
 int spawn_and_wait(char **argv) FAST_FUNC;
 struct nofork_save_area {
 	jmp_buf die_jmp;

libbb/vfork_daemon_rexec.c

@@ -97,7 +97,7 @@ int FAST_FUNC wait4pid(pid_t pid)
 	if (WIFEXITED(status))
 		return WEXITSTATUS(status);
 	if (WIFSIGNALED(status))
-		return WTERMSIG(status) + 1000;
+		return WTERMSIG(status) + 0x180;
 	return 0;
 }
 

mailutils/mime.c

@@ -357,7 +357,7 @@ static int parse(const char *boundary, char **argv)
 			if (opts & OPT_X) {
 				signal(SIGPIPE, SIG_DFL);
 				// exit if helper exited >0
-				rc = wait4pid(pid);
+				rc = (wait4pid(pid) & 0xff);
 				if (rc)
 					return rc+20;
 			}

miscutils/devfsd.c

@@ -751,7 +751,7 @@ static void action_modload(const struct devfsd_notify_struct *info,
 	argv[4] = concat_path_file("/dev", info->devname); /* device */
 	argv[5] = NULL;
 
-	wait4pid(xspawn(argv));
+	spawn_and_wait(argv);
 	free(argv[4]);
 }  /*  End Function action_modload  */
 
@@ -783,7 +783,7 @@ static void action_execute(const struct devfsd_notify_struct *info,
 		argv[count] = largv[count];
 	}
 	argv[count] = NULL;
-	wait4pid(spawn(argv));
+	spawn_and_wait(argv);
 }   /*  End Function action_execute  */
 
 

miscutils/inotifyd.c

@@ -155,7 +155,7 @@ int inotifyd_main(int argc, char **argv)
 				args[1] = events;
 				args[2] = watches[ie->wd];
 				args[3] = ie->len ? ie->name : NULL;
-				wait4pid(xspawn((char **)args));
+				spawn_and_wait((char **)args);
 				// we are done if all files got final x event
 				if (ie->mask & 0x8000) {
 					if (--argc <= 0)

networking/ifplugd.c

@@ -132,10 +132,10 @@ static int run_script(const char *action)
 	argv[3] = (char*) G.extra_arg;
 	argv[4] = NULL;
 
-	/* r < 0 - can't exec, 0 <= r < 1000 - exited, >1000 - killed by sig (r-1000) */
-	r = wait4pid(spawn(argv));
+	/* r < 0 - can't exec, 0 <= r < 0x180 - exited, >=0x180 - killed by sig (r-0x180) */
+	r = spawn_and_wait(argv);
 
-	bb_error_msg("exit code: %d", r);
+	bb_error_msg("exit code: %d", r & 0xff);
 	return (option_mask32 & FLAG_IGNORE_RETVAL) ? 0 : r;
 
 #else /* insanity */

networking/ntpd.c

@@ -772,7 +772,7 @@ static void run_script(const char *action, double offset)
 
 	/* Don't want to wait: it may run hwclock --systohc, and that
 	 * may take some time (seconds): */
-	/*wait4pid(spawn(argv));*/
+	/*spawn_and_wait(argv);*/
 	spawn(argv);
 
 	unsetenv("stratum");

networking/udhcp/script.c

@@ -271,7 +271,7 @@ void FAST_FUNC udhcp_run_script(struct dhcp_packet *packet, const char *name)
 	argv[0] = (char*) client_config.script;
 	argv[1] = (char*) name;
 	argv[2] = NULL;
-	wait4pid(spawn(argv));
+	spawn_and_wait(argv);
 
 	for (curr = envp; *curr; curr++) {
 		log2(" %s", *curr);

networking/zcip.c

@@ -160,13 +160,13 @@ static int run(char *argv[3], const char *param, struct in_addr *ip)
 	}
 	bb_info_msg(fmt, argv[2], argv[0], addr);
 
-	status = wait4pid(spawn(argv + 1));
+	status = spawn_and_wait(argv + 1);
 	if (status < 0) {
 		bb_perror_msg("%s %s %s" + 3, argv[2], argv[0]);
 		return -errno;
 	}
 	if (status != 0)
-		bb_error_msg("script %s %s failed, exitcode=%d", argv[1], argv[2], status);
+		bb_error_msg("script %s %s failed, exitcode=%d", argv[1], argv[2], status & 0xff);
 	return status;
 }
 

util-linux/mount.c

@@ -456,7 +456,7 @@ static int mount_it_now(struct mntent *mp, long vfsflags, char *filteropts)
 				args[rc++] = filteropts;
 			}
 			args[rc] = NULL;
-			rc = wait4pid(spawn(args));
+			rc = spawn_and_wait(args);
 			free(args[0]);
 			if (!rc)
 				break;
@@ -1633,7 +1633,7 @@ static int singlemount(struct mntent *mp, int ignore_busy)
 		}
 		args[n++] = mp->mnt_dir;
 		args[n] = NULL;
-		rc = wait4pid(xspawn(args));
+		rc = spawn_and_wait(args);
 		goto report_error;
 	}