>From e4f2a5f97771c4a74e0bdef1c1e4a0d2735cef15 Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Sun, 22 Jul 2018 09:50:20 -0700
Subject: [PATCH 1/2] df: avoid multibyte character corruption on macOS

Problem reported by Chih-Hsuan Yen (Bug#32236).
* NEWS: Mention the bug fix.
* src/df.c: Include wchar.h and wctype.h.
(hide_problematic_chars): Respect multibyte encodings
when replacing problematic characters or bytes with '?'.
---
 NEWS     |  4 ++++
 src/df.c | 35 +++++++++++++++++++++++++----------
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/NEWS b/NEWS
index af1a990..aa3b4f9 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,10 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** Bug fixes
+
+  df no longer corrupts displayed multibyte characters on macOS.
+
 
 * Noteworthy changes in release 8.30 (2018-07-01) [stable]
 
diff --git a/src/df.c b/src/df.c
index 1178865..52be414b 100644
--- a/src/df.c
+++ b/src/df.c
@@ -23,6 +23,8 @@
 #include <sys/types.h>
 #include <getopt.h>
 #include <assert.h>
+#include <wchar.h>
+#include <wctype.h>
 
 #include "system.h"
 #include "canonicalize.h"
@@ -271,21 +273,34 @@ static struct option const long_options[] =
   {NULL, 0, NULL, 0}
 };
 
-/* Replace problematic chars with '?'.
-   Since only control characters are currently considered,
-   this should work in all encodings.  */
+/* Replace problematic chars with '?'.  */
 
-static char*
+static void
 hide_problematic_chars (char *cell)
 {
-  char *p = cell;
-  while (*p)
+  char *srcend = cell + strlen (cell);
+  char *dst = cell;
+  mbstate_t mbstate = { 0, };
+  size_t n;
+
+  for (char *src = cell; src != srcend; src += n)
     {
-      if (iscntrl (to_uchar (*p)))
-        *p = '?';
-      p++;
+      wchar_t wc;
+      size_t srcbytes = srcend - src;
+      n = mbrtowc (&wc, src, srcbytes, &mbstate);
+      if (n <= srcbytes && !iswcntrl (wc))
+        {
+          memcpy (dst, src, n);
+          dst += n;
+        }
+      else
+        {
+          *dst++ = '?';
+          memset (&mbstate, 0, sizeof mbstate);
+        }
     }
-  return cell;
+
+  *dst = '\0';
 }
 
 /* Dynamically allocate a row of pointers in TABLE, which
-- 
2.7.4