main/busybox: backport fix for ash process substitutions

This patch is from the busybox ML and not yet merged upstream [1].
However, given the simplicity of this patch I think it is fine to apply
it anyhow for now. Especially considering that the fixed error
potentially breaks a few shell scripts.

Fixes #12960

[1]: http://lists.busybox.net/pipermail/busybox/2021-August/089128.html

2 files changed, 86 insertions, 3 deletions

diff --git a/main/busybox/0001-ash-regressions-in-process-substitution.patch b/main/busybox/0001-ash-regressions-in-process-substitution.patch
new file mode 100644
index 00000000000..98fdba7917d
--- /dev/null
+++ b/main/busybox/0001-ash-regressions-in-process-substitution.patch
@@ -0,0 +1,80 @@
+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 == $BASH_XTRACEFD when it is changed.
+@@ -13476,9 +13483,6 @@ cmdloop(int top)
+ #if JOBS
+ 		if (doing_jobctl)
+ 			showjobs(SHOW_CHANGED|SHOW_STDERR);
+-#endif
+-#if BASH_PROCESS_SUBST
+-		unwindredir(NULL);
+ #endif
+ 		inter = 0;
+ 		if (iflag && top) {
diff --git a/main/busybox/APKBUILD b/main/busybox/APKBUILD
index 243efce27bd..01902f30ac1 100644
--- a/main/busybox/APKBUILD
+++ b/main/busybox/APKBUILD
@@ -4,7 +4,7 @@
 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=busybox
 pkgver=1.34.0
-pkgrel=1
+pkgrel=2
 pkgdesc="Size optimized toolbox of many common UNIX utilities"
 url="https://busybox.net/"
 arch="all"
@@ -21,10 +21,12 @@ options="suid !check"
 replaces="busybox-initscripts" # move of default.script
 triggers="busybox.trigger=/bin:/usr/bin:/sbin:/usr/sbin:/lib/modules/*"
 source="https://busybox.net/downloads/busybox-$pkgver.tar.bz2
+	0001-rev-correct-output-for-long-input-lines.patch
+	0001-ash-regressions-in-process-substitution.patch
+
 	0001-nologin-Install-applet-to-sbin-instead-of-usr-sbin.patch
 	0001-adduser-default-to-sbin-nologin-as-shell-for-system-.patch
 	0001-properly-fix-wget-https-support.patch
-	0001-rev-correct-output-for-long-input-lines.patch
 	0002-fsck-resolve-LABEL-.-UUID-.-spec-to-device.patch
 	0003-ash-exec-busybox.static.patch
 	0004-app-location-for-cpio-vi-and-lspci.patch
@@ -229,10 +231,11 @@ ifupdown() {
 
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