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authorPeter Stephenson <p.stephenson@samsung.com>2018-04-13 12:09:34 +0100
committerPeter Stephenson <p.stephenson@samsung.com>2018-04-17 17:14:20 +0100
commit3c74891fcd68d37c1629943f703ac70428e3ce9f (patch)
treeb6da0e207af9a39e94e6e809690c5ea16b14b08c /Src
parent181f5cfabe2a60d668f4e5fc03359df1b13ce490 (diff)
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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.
Diffstat (limited to 'Src')
-rw-r--r--Src/exec.c17
-rw-r--r--Src/signals.c13
2 files changed, 29 insertions, 1 deletions
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);
diff --git a/Src/signals.c b/Src/signals.c
index 94f379e72..2a6aa3f24 100644
--- a/Src/signals.c
+++ b/Src/signals.c
@@ -537,6 +537,19 @@ wait_for_processes(void)
 #else
 		update_process(pn, status);
 #endif
+		if (pn->pid == jn->gleader) {
+		    jn->gleader = 0;
+		    if (!(jn->stat & STAT_NOSTTY)) {
+			/*
+			 * This PID was in control of the terminal;
+			 * reclaim terminal now it has exited.
+			 * It's still possible some future forked
+			 * process of this job will become group
+			 * leader, however.
+			 */
+			attachtty(mypgrp);
+		    }
+		}
 	    }
 	    update_job(jn);
 	} else if (findproc(pid, &jn, &pn, 1)) {