Module Name: src
Committed By: kre
Date: Sat Dec 21 18:54:15 UTC 2019
Modified Files:
src/bin/sh: eval.c
Log Message:
Use fork() rather than vfork() when forking to run a background
process with redirects. If we use vfork() and a redirect hangs
(eg: opening a fifo) which the parent was intended to unhang,
then the parent never gets to continue to unhang the child.
eg: mkfifo f; cat <f &; echo foo>f
The parent should not be waiting for a background process, even
just for its exec() to complete. if there are no redirects there
is (should be) nothing left that might be done that will cause any
noticeable delay, so vfork() should be safe in all other cases.
To generate a diff of this commit:
cvs rdiff -u -r1.176 -r1.177 src/bin/sh/eval.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/bin/sh/eval.c
diff -u src/bin/sh/eval.c:1.176 src/bin/sh/eval.c:1.177
--- src/bin/sh/eval.c:1.176 Mon Dec 9 00:14:24 2019
+++ src/bin/sh/eval.c Sat Dec 21 18:54:15 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: eval.c,v 1.176 2019/12/09 00:14:24 kre Exp $ */
+/* $NetBSD: eval.c,v 1.177 2019/12/21 18:54:15 kre Exp $ */
/*-
* Copyright (c) 1993
@@ -37,7 +37,7 @@
#if 0
static char sccsid[] = "@(#)eval.c 8.9 (Berkeley) 6/8/95";
#else
-__RCSID("$NetBSD: eval.c,v 1.176 2019/12/09 00:14:24 kre Exp $");
+__RCSID("$NetBSD: eval.c,v 1.177 2019/12/21 18:54:15 kre Exp $");
#endif
#endif /* not lint */
@@ -552,8 +552,8 @@ evalsubshell(union node *n, int flags)
forkshell(jp = makejob(n, 1), n, backgnd?FORK_BG:FORK_FG) == 0) {
if (backgnd)
flags &=~ EV_TESTED;
- redirect(n->nredir.redirect, REDIR_KEEP);
INTON;
+ redirect(n->nredir.redirect, REDIR_KEEP);
evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
} else if (backgnd)
exitstatus = 0;
@@ -1086,7 +1086,8 @@ evalcommand(union node *cmd, int flgs, s
* child's address space is actually shared with the parent as
* we rely on this.
*/
- if (usefork == 0 && cmdentry.cmdtype == CMDNORMAL) {
+ if (usefork == 0 && cmdentry.cmdtype == CMDNORMAL &&
+ (!cmd->ncmd.backgnd || cmd->ncmd.redirect == NULL)) {
pid_t pid;
int serrno;
