From 3c74891fcd68d37c1629943f703ac70428e3ce9f Mon Sep 17 00:00:00 2001
From: Peter Stephenson
Date: Fri, 13 Apr 2018 12:09:34 +0100
Subject: 42630: Improve process group handling in pipelines.
If process group leader exits, allow a newly forked process to become
process leader. If a foreground job, reattach the shell to the
terminal until that happens.
Unblock signals when reading output for command subsitution so that
we can do this reattaching immediately.
---
Src/exec.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
(limited to 'Src/exec.c')
diff --git a/Src/exec.c b/Src/exec.c
index 216057aa7..f6c768f37 100644
--- a/Src/exec.c
+++ b/Src/exec.c
@@ -4576,10 +4576,20 @@ readoutput(int in, int qt, int *readerror)
char *buf, *ptr;
int bsiz, c, cnt = 0;
FILE *fin;
+ int q = queue_signal_level();
fin = fdopen(in, "r");
ret = newlinklist();
ptr = buf = (char *) hcalloc(bsiz = 64);
+ /*
+ * We need to be sensitive to SIGCHLD else we can be
+ * stuck forever with important processes unreaped.
+ * The case that triggered this was where the exiting
+ * process is group leader of the foreground process and we need
+ * to reclaim the terminal else ^C doesn't work.
+ */
+ dont_queue_signals();
+ child_unblock();
while ((c = fgetc(fin)) != EOF || errno == EINTR) {
if (c == EOF) {
errno = 0;
@@ -4592,13 +4602,18 @@ readoutput(int in, int qt, int *readerror)
cnt++;
}
if (++cnt >= bsiz) {
- char *pp = (char *) hcalloc(bsiz *= 2);
+ char *pp;
+ queue_signals();
+ pp = (char *) hcalloc(bsiz *= 2);
+ dont_queue_signals();
memcpy(pp, buf, cnt - 1);
ptr = (buf = pp) + cnt - 1;
}
*ptr++ = c;
}
+ child_block();
+ restore_queue_signals(q);
if (readerror)
*readerror = ferror(fin) ? errno : 0;
fclose(fin);
--
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