hush: fix "(sleep 1; exit 3) & sleep 2; echo $?; wait $!; echo $?"

"wait $!" may be just a bit too late: backgrounded $! is gone.
Do not bomb out in this case.

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

1 files changed, 14 insertions, 4 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 1f8a3e607..7c2f157b8 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -9529,13 +9529,22 @@ static int FAST_FUNC builtin_wait(char **argv)
                 if (errno || pid <= 0) {
                         /* mimic bash message */
                         bb_error_msg("wait: '%s': not a pid or valid job spec", *argv);
-                        return EXIT_FAILURE;
+                        ret = EXIT_FAILURE;
+                        continue; /* bash checks all argv[] */
                 }
                 /* Do we have such child? */
                 ret = waitpid(pid, &status, WNOHANG);
                 if (ret < 0) {
                         /* No */
                         if (errno == ECHILD) {
+                                if (G.last_bg_pid > 0 && pid == G.last_bg_pid) {
+                                        /* "wait $!" but last bg task has already exited. Try:
+                                         * (sleep 1; exit 3) & sleep 2; echo $?; wait $!; echo $?
+                                         * In bash it prints exitcode 0, then 3.
+                                         */
+                                        ret = 0; /* FIXME */
+                                        continue;
+                                }
                                 /* Example: "wait 1". mimic bash message */
                                 bb_error_msg("wait: pid %d is not a child of this shell", (int)pid);
                         } else {
@@ -9543,7 +9552,9 @@ static int FAST_FUNC builtin_wait(char **argv)
                                 bb_perror_msg("wait %s", *argv);
                         }
                         ret = 127;
-                } else if (ret == 0) {
+                        continue; /* bash checks all argv[] */
+                }
+                if (ret == 0) {
                         /* Yes, and it still runs */
                         ret = wait_for_child_or_signal(pid);
                 } else {
@@ -9553,8 +9564,7 @@ static int FAST_FUNC builtin_wait(char **argv)
                         if (WIFSIGNALED(status))
                                 ret = 128 + WTERMSIG(status);
                 }
-                argv++;
-        } while (*argv);
+        } while (*++argv);
 
         return ret;
 }