implement `wait` builtin

1 files changed, 35 insertions, 0 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 6f34ce1c3..498b14e72 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -524,6 +524,7 @@ static int builtin_shift(char **argv);
 static int builtin_source(char **argv);
 static int builtin_umask(char **argv);
 static int builtin_unset(char **argv);
+static int builtin_wait(char **argv);
 #if ENABLE_HUSH_LOOPS
 static int builtin_break(char **argv);
 static int builtin_continue(char **argv);
@@ -582,6 +583,7 @@ static const struct built_in_command bltins[] = {
 //      BLTIN("ulimit", builtin_not_written, "Control resource limits"),
         BLTIN("umask" , builtin_umask, "Set file creation mask"),
         BLTIN("unset" , builtin_unset, "Unset environment variable"),
+        BLTIN("wait"  , builtin_wait, "Wait for process"),
 #if ENABLE_HUSH_HELP
         BLTIN("help"  , builtin_help, "List shell built-in commands"),
 #endif
@@ -4895,6 +4897,39 @@ static int builtin_unset(char **argv)
         return EXIT_SUCCESS;
 }
 
+/* http://www.opengroup.org/onlinepubs/9699919799/utilities/wait.html */
+static int builtin_wait(char **argv)
+{
+        int ret = EXIT_SUCCESS;
+        int status;
+
+        if (argv[1] == NULL)
+                /* don't care about exit status */
+                wait(&status);
+
+        while (argv[1]) {
+                char *endp;
+                pid_t pid = bb_strtou(argv[1], &endp, 10);
+                if (*endp) {
+                        bb_perror_msg("wait %s", argv[1]);
+                        return EXIT_FAILURE;
+                } else if (waitpid(pid, &status, 0) == pid) {
+                        if (WIFSIGNALED(status))
+                                ret = 128 + WTERMSIG(status);
+                        else if (WIFEXITED(status))
+                                ret = WEXITSTATUS(status);
+                        else
+                                ret = EXIT_FAILURE;
+                } else {
+                        bb_perror_msg("wait %s", argv[1]);
+                        ret = 127;
+                }
+                ++argv;
+        }
+
+        return ret;
+}
+
 #if ENABLE_HUSH_LOOPS
 static int builtin_break(char **argv)
 {