doc: use ASCII in .texi files where UTF-8 isn't needed

[gnulib.git] / lib / strncasecmp.c

diff --git a/lib/strncasecmp.c b/lib/strncasecmp.c
index 55c0f2e..29cd1e7 100644 (file)
--- a/lib/strncasecmp.c
+++ b/lib/strncasecmp.c
@@ -1,16 +1,33 @@
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
+/* strncasecmp.c -- case insensitive string comparator
+   Copyright (C) 1998-1999, 2005-2007, 2009-2014 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <string.h>
 
-#include <sys/types.h>
 #include <ctype.h>
+#include <limits.h>
 
 #define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
 
-/* Compare no more than N characters of S1 and S2,
-   ignoring case, returning less than, equal to or
-   greater than zero if S1 is lexicographically less
-   than, equal to or greater than S2.  */
+/* Compare no more than N bytes of strings S1 and S2, ignoring case,
+   returning less than, equal to or greater than zero if S1 is
+   lexicographically less than, equal to or greater than S2.
+   Note: This function cannot work correctly in multibyte locales.  */
 
 int
 strncasecmp (const char *s1, const char *s2, size_t n)
@@ -24,11 +41,22 @@ strncasecmp (const char *s1, const char *s2, size_t n)
 
   do
     {
-      c1 = TOLOWER (*p1++);
-      c2 = TOLOWER (*p2++);
-      if (c1 == '\0' || c1 != c2)
-        return c1 - c2;
-    } while (--n > 0);
+      c1 = TOLOWER (*p1);
+      c2 = TOLOWER (*p2);
+
+      if (--n == 0 || c1 == '\0')
+        break;
+
+      ++p1;
+      ++p2;
+    }
+  while (c1 == c2);
 
-  return c1 - c2;
+  if (UCHAR_MAX <= INT_MAX)
+    return c1 - c2;
+  else
+    /* On machines where 'char' and 'int' are types of the same size, the
+       difference of two 'unsigned char' values - including the sign bit -
+       doesn't fit in an 'int'.  */
+    return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
 }