PATCH v2: 48168: Fix handling of NUL bytes in zexpandtabs multibyte version

[Mikael Magnusson <mikachu@gmail.com>]

---

 Src/utils.c        | 5 ++++-
 Test/B03print.ztst | 9 +++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/Src/utils.c b/Src/utils.c
index 8fcea5362a..f8cbe65ba5 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -5936,8 +5936,11 @@ zexpandtabs(const char *s, int len, int width, int startpos, FILE *fout,
 		memset(&mbs, 0, sizeof(mbs));
 		s++;
 		len--;
-	    } else if (ret == MB_INCOMPLETE) {
+	    } else if (ret == MB_INCOMPLETE ||
 		/* incomplete at end --- assume likewise, best we've got */
+	               ret == 0) {
+		/* NUL character returns 0, which would loop infinitely, so advance
+		 * one byte in this case too */
 		s++;
 		len--;
 	    } else {
diff --git a/Test/B03print.ztst b/Test/B03print.ztst
index 5634239346..d8618de7d4 100644
--- a/Test/B03print.ztst
+++ b/Test/B03print.ztst
@@ -304,15 +304,16 @@
  foo=$'one\ttwo\tthree\tfour\n'
  foo+=$'\tone\ttwo\tthree\tfour\n'
  foo+=$'\t\tone\t\ttwo\t\tthree\t\tfour'
- print -x4 $foo
- print -X4 $foo
+ foo+='\0' # regression test for multibyte tab expand
+ print -x4 $foo | sed 's/\x00/nul/' # avoid raw nul byte in expected output below
+ print -X4 $foo | sed 's/\x00/nul/'
 0:Tab expansion by print
 >one	two	three	four
 >    one	two	three	four
->        one		two		three		four
+>        one		two		three		fournul
 >one two three   four
 >    one two three   four
->        one     two     three       four
+>        one     two     three       fournul
 
  unset foo
  print -v foo once more
-- 
2.15.1