wcwidth() fix in file(1)

[Stefan Sperling]

Make the file_mbswidth() function cope if wcwidth() returns -1.

Maybe this should just call wcswidth() but I'll leave that for another day.

Index: file.c
===================================================================
RCS file: /cvs/src/usr.bin/file/file.c,v
retrieving revision 1.22
diff -u -p -r1.22 file.c
--- file.c      27 Oct 2009 23:59:37 -0000      1.22
+++ file.c      3 Apr 2011 22:01:55 -0000
@@ -424,6 +424,7 @@ file_mbswidth(const char *s)
        wchar_t nextchar;
        (void)memset(&state, 0, sizeof(mbstate_t));
        old_n = n = strlen(s);
+       int w;
 
        while (n > 0) {
                bytesconsumed = mbrtowc(&nextchar, s, n, &state);
@@ -438,8 +439,11 @@ file_mbswidth(const char *s)
                         * is always right
                         */
                        width++;
-               } else
-                       width += wcwidth(nextchar);
+               } else {
+                       w = wcwidth(nextchar);
+                       if (w > 0)
+                               width += w;
+               }
 
                s += bytesconsumed, n -= bytesconsumed;
        }