From 191bcb948f7191c36eefe634336f5fc5c0c4c2be Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Sat, 14 Aug 2021 12:20:38 -0400
Subject: [PATCH] config.sub: work around command assignment bug in some shells

When combining variable assignments with a shell command, some older
shells (notably heirloom-sh and presumably also Solaris 10 /bin/sh)
have a bug which causes the assignment to alter the current execution
environment whenever the command is a shell built-in.  For example:

  % dash -c 'x=good; x=bad echo >/dev/null; echo $x'
  good

  % jsh -c 'x=good; x=bad echo >/dev/null; echo $x'
  bad

The config.sub script contains a few commands of the form:

  IFS=- read ...

which triggers this bug, causing the IFS assignment to persist for the
remainder of the script.  This can cause misbehaviour in certain cases,
for example:

  % jsh config.sub i386-linux-gnu
  config.sub: test: unknown operator gnu

  % jsh config.sub i386-gnu/linux
  sed: can't read s|gnu/linux|gnu|: No such file or directory
  Invalid configuration `i386-gnu/linux': OS `' not recognized

* config.sub: Save and restore IFS explicitly to avoid shell bugs.
* doc/config.sub.1: Regenerate.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---
 config.sub       | 8 +++++++-
 doc/config.sub.1 | 2 +-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/config.sub b/config.sub
index 07dd7f6..d74fb6d 100755
--- a/config.sub
+++ b/config.sub
@@ -4,7 +4,7 @@
 
 # shellcheck disable=SC2006,SC2268 # see below for rationale
 
-timestamp='2021-08-04'
+timestamp='2021-08-14'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -121,9 +121,11 @@ esac
 
 # Split fields of configuration type
 # shellcheck disable=SC2162
+saved_IFS=$IFS
 IFS="-" read field1 field2 field3 field4 <<EOF
 $1
 EOF
+IFS=$saved_IFS
 
 # Separate into logical components for further validation
 case $1 in
@@ -935,9 +937,11 @@ case $basic_machine in
 
 	*-*)
 		# shellcheck disable=SC2162
+		saved_IFS=$IFS
 		IFS="-" read cpu vendor <<EOF
 $basic_machine
 EOF
+		IFS=$saved_IFS
 		;;
 	# We use `pc' rather than `unknown'
 	# because (1) that's what they normally are, and
@@ -1317,9 +1321,11 @@ case $basic_os in
 		;;
 	*-*)
 		# shellcheck disable=SC2162
+		saved_IFS=$IFS
 		IFS="-" read kernel os <<EOF
 $basic_os
 EOF
+		IFS=$saved_IFS
 		;;
 	# Default OS when just kernel was specified
 	nto*)
diff --git a/doc/config.sub.1 b/doc/config.sub.1
index 7c5c8ae..d9aa396 100644
--- a/doc/config.sub.1
+++ b/doc/config.sub.1
@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.47.16.
-.TH CONFIG.SUB "1" "August 2021" "GNU config.sub (2021-08-04)" "User Commands"
+.TH CONFIG.SUB "1" "August 2021" "GNU config.sub (2021-08-14)" "User Commands"
 .SH NAME
 config.sub \- validate and canonicalize a configuration triplet
 .SH SYNOPSIS