1 files changed, 76 insertions, 0 deletions
diff --git a/lib/c-strcasestr.c b/lib/c-strcasestr.c
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+++ b/lib/c-strcasestr.c
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+/* c-strcasestr.c -- case insensitive substring search in C locale
+   Copyright (C) 2005-2023 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2005.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file 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 Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "c-strcasestr.h"
+
+#include <string.h>
+
+#include "c-ctype.h"
+#include "c-strcase.h"
+
+/* Two-Way algorithm.  */
+#define RETURN_TYPE char *
+#define AVAILABLE(h, h_l, j, n_l)                       \
+  (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l))     \
+   && ((h_l) = (j) + (n_l)))
+#define CANON_ELEMENT c_tolower
+#define CMP_FUNC(p1, p2, l)                             \
+  c_strncasecmp ((const char *) (p1), (const char *) (p2), l)
+#include "str-two-way.h"
+
+/* Find the first occurrence of NEEDLE in HAYSTACK, using case-insensitive
+   comparison from the C locale, regardless of the current locale.  */
+char *
+c_strcasestr (const char *haystack_start, const char *needle_start)
+{
+  const char *haystack = haystack_start;
+  const char *needle = needle_start;
+  size_t needle_len; /* Length of NEEDLE.  */
+  size_t haystack_len; /* Known minimum length of HAYSTACK.  */
+  bool ok = true; /* True if NEEDLE is prefix of HAYSTACK.  */
+
+  /* Determine length of NEEDLE, and in the process, make sure
+     HAYSTACK is at least as long (no point processing all of a long
+     NEEDLE if HAYSTACK is too short).  */
+  while (*haystack && *needle)
+    ok &= (c_tolower ((unsigned char) *haystack++)
+           == c_tolower ((unsigned char) *needle++));
+  if (*needle)
+    return NULL;
+  if (ok)
+    return (char *) haystack_start;
+  needle_len = needle - needle_start;
+  haystack = haystack_start + 1;
+  haystack_len = needle_len - 1;
+
+  /* Perform the search.  Abstract memory is considered to be an array
+     of 'unsigned char' values, not an array of 'char' values.  See
+     ISO C 99 section 6.2.6.1.  */
+  if (needle_len < LONG_NEEDLE_THRESHOLD)
+    return two_way_short_needle ((const unsigned char *) haystack,
+                                 haystack_len,
+                                 (const unsigned char *) needle_start,
+                                 needle_len);
+  return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
+                              (const unsigned char *) needle_start,
+                              needle_len);
+}
+
+#undef LONG_NEEDLE_THRESHOLD