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

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@inlv.org>
Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

3 files changed, 5 insertions, 0 deletions

diff --git a/shell/ash.c b/shell/ash.c
index b5a2d961d..5613e1f33 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 000000000..6f4247a62
--- /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 000000000..d04b2cbb6
--- /dev/null
+++ b/shell/ash_test/ash-vars/var-utf8-length.tests
@@ -0,0 +1,2 @@
+X=abcdÉfghÍjklmnÓpqrstÚvwcyz
+echo ${#X}