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From dab3c63da581f0d3d58e3ea1a620474eb5dad0ee Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Mon, 30 Aug 2021 20:31:42 +0100
Subject: [PATCH] ash: regressions in process substitution
Stacy Harper reports that this script:
test() { . /tmp/bb_test; }
echo "export TEST=foo" >/tmp/bb_test
test 2>/dev/null
echo "$TEST"
correctly prints 'foo' in BusyBox 1.33 but hangs in 1.34.
Bisection suggested the problem was caused by commit a1b0d3856 (ash: add
process substitution in bash-compatibility mode). Removing the call to
unwindredir() in cmdloop() introduced in that commit makes the script
work again.
Additionally, these examples of process substitution:
while true; do cat <(echo hi); done
f() { while true; do cat <(echo hi); done }
f
result in running out of file descriptors. This is a regression from
v5 of the process substitution patch caused by changes to evalcommand()
not being transferred to v6.
function old new delta
static.pushredir - 99 +99
evalcommand 1729 1750 +21
exitreset 69 86 +17
cmdloop 372 365 -7
unwindredir 28 - -28
pushredir 112 - -112
------------------------------------------------------------------------------
(add/remove: 1/2 grow/shrink: 2/1 up/down: 137/-147) Total: -10 bytes
Signed-off-by: Ron Yorston <rmy@pobox.com>
---
shell/ash.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/shell/ash.c b/shell/ash.c
index b5947147a..53c140930 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -10278,6 +10278,9 @@ evalcommand(union node *cmd, int flags)
/* First expand the arguments. */
TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
+#if BASH_PROCESS_SUBST
+ redir_stop = redirlist;
+#endif
file_stop = g_parsefile;
back_exitstatus = 0;
@@ -10356,7 +10359,11 @@ evalcommand(union node *cmd, int flags)
lastarg = nargv[-1];
expredir(cmd->ncmd.redirect);
+#if !BASH_PROCESS_SUBST
redir_stop = pushredir(cmd->ncmd.redirect);
+#else
+ pushredir(cmd->ncmd.redirect);
+#endif
preverrout_fd = 2;
if (BASH_XTRACEFD && xflag) {
/* NB: bash closes fd == $BASH_XTRACEFD when it is changed.
@@ -13476,9 +13483,6 @@ cmdloop(int top)
#if JOBS
if (doing_jobctl)
showjobs(SHOW_CHANGED|SHOW_STDERR);
-#endif
-#if BASH_PROCESS_SUBST
- unwindredir(NULL);
#endif
inter = 0;
if (iflag && top) {
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