[PATCH] reset mbstate on error

[Richard Russon]

This is Karel Zak's patch to fix handling of (illegal) multi-byte chars.

 * mutt_wstr_trunc() does not reset mbrtowc() after error

 * mutt_wstr_trunc() compare signed and unsigned numbers to check for
   maxlen and maxwid limits and does not care about unprintable chars

Addresses: https://github.com/karelzak/mutt-kz/issues/58
Signed-off-by: Karel Zak <k...@redhat.com>

---

diff -urN mutt/curs_lib.c mutt.fix/curs_lib.c
--- mutt/curs_lib.c     2016-03-17 23:22:15.547234169 +0000
+++ mutt.fix/curs_lib.c 2016-03-17 23:16:42.994127967 +0000
@@ -964,8 +964,10 @@
   memset (&mbstate, 0, sizeof (mbstate));
   for (w = 0; n && (cl = mbrtowc (&wc, src, n, &mbstate)); src += cl, n -= cl)
   {
-    if (cl == (size_t)(-1) || cl == (size_t)(-2))
+    if (cl == (size_t)(-1) || cl == (size_t)(-2)) {
       cw = cl = 1;
+      memset(&mbstate, 0, sizeof (mbstate));
+    }
     else
     {
       cw = wcwidth (wc);
@@ -973,6 +975,8 @@
        * until rendered by print_enriched_string (#3364) */
       if (cw < 0 && cl == 1 && src[0] && src[0] < M_TREE_MAX)
        cw = 1;
+      else if (cw < 0)
+       cw = 0;                 /* unprintable wchar */
     }
     if (cl + l > maxlen || cw + w > maxwid)
       break;