1 files changed, 98 insertions, 0 deletions
diff --git a/lib/mbscasecmp.c b/lib/mbscasecmp.c
new file mode 100644
index 0000000..9a1ea4b
--- /dev/null
+++ b/lib/mbscasecmp.c
@@ -0,0 +1,98 @@
+/* Case-insensitive string comparison function.
+   Copyright (C) 1998-1999, 2005-2020 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2005,
+   based on earlier glibc code.
+
+   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 3 of the License, 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 <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <string.h>
+
+#include <ctype.h>
+#include <limits.h>
+
+#include "mbuiter.h"
+
+#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
+
+/* Compare the character 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 may, in multibyte locales, return 0 for strings of
+   different lengths!  */
+int
+mbscasecmp (const char *s1, const char *s2)
+{
+  if (s1 == s2)
+    return 0;
+
+  /* Be careful not to look at the entire extent of s1 or s2 until needed.
+     This is useful because when two strings differ, the difference is
+     most often already in the very few first characters.  */
+  if (MB_CUR_MAX > 1)
+    {
+      mbui_iterator_t iter1;
+      mbui_iterator_t iter2;
+
+      mbui_init (iter1, s1);
+      mbui_init (iter2, s2);
+
+      while (mbui_avail (iter1) && mbui_avail (iter2))
+        {
+          int cmp = mb_casecmp (mbui_cur (iter1), mbui_cur (iter2));
+
+          if (cmp != 0)
+            return cmp;
+
+          mbui_advance (iter1);
+          mbui_advance (iter2);
+        }
+      if (mbui_avail (iter1))
+        /* s2 terminated before s1.  */
+        return 1;
+      if (mbui_avail (iter2))
+        /* s1 terminated before s2.  */
+        return -1;
+      return 0;
+    }
+  else
+    {
+      const unsigned char *p1 = (const unsigned char *) s1;
+      const unsigned char *p2 = (const unsigned char *) s2;
+      unsigned char c1, c2;
+
+      do
+        {
+          c1 = TOLOWER (*p1);
+          c2 = TOLOWER (*p2);
+
+          if (c1 == '\0')
+            break;
+
+          ++p1;
+          ++p2;
+        }
+      while (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);
+    }
+}