Fix mbrtowc() error handling in mutt_which_case().

The function did not reset the increment value on a -2 return value.

Increase the maximum conversion size to the string length, and check
for -2.  Since we're looking at the whole string, we can then just
terminate the loop on either value, assuming a case-sensitive search.

mbrtowc() will return -2 if passed n==0, so add an explicit check for
the end of string and a positive n count.

1 files changed, 4 insertions, 5 deletions

diff --git a/pattern.c b/pattern.c
index 1288a00f..28a33d81 100644
--- a/pattern.c
+++ b/pattern.c
@@ -313,15 +313,14 @@ int mutt_which_case (const char *s)
 {
   wchar_t w;
   mbstate_t mb;
-  size_t l;
+  size_t l, n;
 
   memset (&mb, 0, sizeof (mb));
+  n = mutt_strlen (s);
 
-  for (; (l = mbrtowc (&w, s, MB_CUR_MAX, &mb)) != 0; s += l)
+  for (; n && *s && (l = mbrtowc (&w, s, n, &mb)) != 0; s += l, n -= l)
   {
-    if (l == (size_t) -2)
-      continue; /* shift sequences */
-    if (l == (size_t) -1)
+    if (l == (size_t)(-1) || l == (size_t)(-2))
       return 0; /* error; assume case-sensitive */
     if (iswalpha ((wint_t) w) && iswupper ((wint_t) w))
       return 0; /* case-sensitive */