[git commit branch/1_24_stable] ash: fix error during recursive processing of here document

[Mike Frysinger]

commit: https://git.busybox.net/busybox/commit/?id=4194c2875310c13ee3ca2bb0e1aea6a2ae67c55a
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/1_24_stable

Save the value of the checkkwd flag to prevent it being clobbered
during recursion.

Based on commit ec2c84d from git://git.kernel.org/pub/scm/utils/dash/dash.git
by Herbert Xu.

function                                             old     new   delta
readtoken                                            190     203     +13
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/0 up/down: 13/0)               Total: 13 bytes

Signed-off-by: Ron Yorston <rmy at pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
Signed-off-by: Mike Frysinger <vapier at gentoo.org>
(cherry picked from commit 713f07d906d9171953be0c12e2369869855b6ca6)
---
 shell/ash.c                               | 5 +++--
 shell/ash_test/ash-heredoc/heredoc3.right | 1 +
 shell/ash_test/ash-heredoc/heredoc3.tests | 9 +++++++++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/shell/ash.c b/shell/ash.c
index 8a1628e..256e933 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -11893,6 +11893,7 @@ static int
 readtoken(void)
 {
 	int t;
+	int kwd = checkkwd;
 #if DEBUG
 	smallint alreadyseen = tokpushback;
 #endif
@@ -11906,7 +11907,7 @@ readtoken(void)
 	/*
 	 * eat newlines
 	 */
-	if (checkkwd & CHKNL) {
+	if (kwd & CHKNL) {
 		while (t == TNL) {
 			parseheredoc();
 			t = xxreadtoken();
@@ -11920,7 +11921,7 @@ readtoken(void)
 	/*
 	 * check for keywords
 	 */
-	if (checkkwd & CHKKWD) {
+	if (kwd & CHKKWD) {
 		const char *const *pp;
 
 		pp = findkwd(wordtext);
diff --git a/shell/ash_test/ash-heredoc/heredoc3.right b/shell/ash_test/ash-heredoc/heredoc3.right
new file mode 100644
index 0000000..ce01362
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc3.right
@@ -0,0 +1 @@
+hello
diff --git a/shell/ash_test/ash-heredoc/heredoc3.tests b/shell/ash_test/ash-heredoc/heredoc3.tests
new file mode 100755
index 0000000..96c227c
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc3.tests
@@ -0,0 +1,9 @@
+echo hello >greeting
+cat <<EOF &&
+$(cat greeting)
+EOF
+{
+	echo $?
+	cat greeting
+} >/dev/null
+rm greeting