[git commit] ash: fix corruption of ${#var} if $var contains UTF-8 characters

[Mike Frysinger]

commit: https://git.busybox.net/busybox/commit/?id=3e3bfb896e0dd8a54caad9c6264e2452566b4012
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

As reported in bug 8506:

   $ X=abcdÉfghÍjklmnÓpqrstÚvwcyz
   $ echo ${#X}
   abcd26

The result should be 26.

This regression was introduced by:

   <d68d1fb> 2015-05-18 [Ron Yorston]  ash: code shrink around varvalue

The length in characters was being used to discard the contents of
the variable instead of the length in bytes.

URL: https://bugs.busybox.net/8506
Reported-by: Martijn Dekker <martijn at inlv.org>
Signed-off-by: Ron Yorston <rmy at pobox.com>
Signed-off-by: Mike Frysinger <vapier at gentoo.org>
---
 shell/ash.c                                   | 2 ++
 shell/ash_test/ash-vars/var-utf8-length.right | 1 +
 shell/ash_test/ash-vars/var-utf8-length.tests | 2 ++
 3 files changed, 5 insertions(+)

diff --git a/shell/ash.c b/shell/ash.c
index b5a2d96..5613e1f 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -6692,6 +6692,8 @@ varvalue(char *name, int varflags, int flags, struct strlist *var_str_list)
 		if (subtype == VSLENGTH && len > 0) {
 			reinit_unicode_for_ash();
 			if (unicode_status == UNICODE_ON) {
+				STADJUST(-len, expdest);
+				discard = 0;
 				len = unicode_strlen(p);
 			}
 		}
diff --git a/shell/ash_test/ash-vars/var-utf8-length.right b/shell/ash_test/ash-vars/var-utf8-length.right
new file mode 100644
index 0000000..6f4247a
--- /dev/null
+++ b/shell/ash_test/ash-vars/var-utf8-length.right
@@ -0,0 +1 @@
+26
diff --git a/shell/ash_test/ash-vars/var-utf8-length.tests b/shell/ash_test/ash-vars/var-utf8-length.tests
new file mode 100755
index 0000000..d04b2cb
--- /dev/null
+++ b/shell/ash_test/ash-vars/var-utf8-length.tests
@@ -0,0 +1,2 @@
+X=abcdÉfghÍjklmnÓpqrstÚvwcyz
+echo ${#X}