ash: allow wait to handle more than 64 processeswaitfor

WaitForMultipleObjects() can only handle 64 processes (actually,
MAXIMUM_WAIT_OBJECTS) in a single call.  Using the 'wait' shell
built-in after a command like:

   for i in $(seq 1 70); do echo $i; sleep 10 & done

resulted in an uninterruptible 'wait'.

Handle processes in batches of MAXIMUM_WAIT_OBJECTS.

The problem was noted by Morgan Bartlett, who also supplied a
fix which I claim to have 'improved'.

Adds 32-48 bytes.

Signed-off-by: Ron Yorston <rmy@pobox.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/shell/ash.c b/shell/ash.c
index a114fdbb0..72cdf5f59 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -4928,7 +4928,18 @@ waitpid_child(int *status, DWORD blocking)
 
         if (pid_nr) {
                 do {
-                        idx = WaitForMultipleObjects(pid_nr, proclist, FALSE, blocking);
+                        for (i = 0; i < pid_nr; i += MAXIMUM_WAIT_OBJECTS) {
+                                DWORD nr;
+                                TRACE(("poll many: i %d, pidnr: %d, maxwait: %d, blocking: %d\n", i, pid_nr, MAXIMUM_WAIT_OBJECTS, blocking));
+                                nr = i + MAXIMUM_WAIT_OBJECTS > pid_nr ?
+                                                (DWORD)(pid_nr - i) : MAXIMUM_WAIT_OBJECTS;
+                                idx = WaitForMultipleObjects(nr, proclist + i, FALSE, blocking);
+                                TRACE(("poll result: %d\n", idx));
+                                if (idx != WAIT_TIMEOUT) {
+                                        idx += i;
+                                        break;
+                                }
+                        }
                         if (idx < pid_nr) {
                                 GetExitCodeProcess(proclist[idx], &win_status);
                                 *status = exit_code_to_wait_status(win_status);