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[thirdparty/glibc.git] / string / strcasestr.c

diff --git a/string/strcasestr.c b/string/strcasestr.c
index 7c8cbcc4cb4473b8f094a4055460953592a6cb98..ea729449da46a559b46d043c9b254702c4d62589 100644 (file)
--- a/string/strcasestr.c
+++ b/string/strcasestr.c
@@ -1,5 +1,5 @@
 /* Return the offset of one string within another.
-   Copyright (C) 1994-2013 Free Software Foundation, Inc.
+   Copyright (C) 1994-2019 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -14,7 +14,7 @@
 
    You should have received a copy of the GNU Lesser General Public
    License along with the GNU C Library; if not, see
-   <http://www.gnu.org/licenses/>.  */
+   <https://www.gnu.org/licenses/>.  */
 
 /*
  * My personal strstr() implementation that beats most other algorithms.
@@ -25,10 +25,6 @@
  *
  * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de        */
 
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
-
 /* Specification.  */
 #include <string.h>
 
@@ -41,8 +37,9 @@
 /* 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)))
+  (((j) + (n_l) <= (h_l)) \
+   || ((h_l) += __strnlen ((void*)((h) + (h_l)), (n_l) + 512), \
+       (j) + (n_l) <= (h_l)))
 #define CHECK_EOL (1)
 #define RET0_IF_0(a) if (!a) goto ret0
 #define CANON_ELEMENT(c) TOLOWER (c)
@@ -62,31 +59,22 @@
    case-insensitive comparison.  This function gives unspecified
    results in multibyte locales.  */
 char *
-STRCASESTR (const char *haystack_start, const char *needle_start)
+STRCASESTR (const char *haystack, const char *needle)
 {
-  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 &= (TOLOWER ((unsigned char) *haystack)
-            == TOLOWER ((unsigned char) *needle));
-      haystack++;
-      needle++;
-    }
-  if (*needle)
+
+  /* Handle empty NEEDLE special case.  */
+  if (needle[0] == '\0')
+    return (char *) haystack;
+
+  /* Ensure HAYSTACK length is at least as long as NEEDLE length.
+     Since a match may occur early on in a huge HAYSTACK, use strnlen
+     and read ahead a few cachelines for improved performance.  */
+  needle_len = strlen (needle);
+  haystack_len = __strnlen (haystack, needle_len + 256);
+  if (haystack_len < needle_len)
     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
@@ -94,10 +82,10 @@ STRCASESTR (const char *haystack_start, const char *needle_start)
   if (needle_len < LONG_NEEDLE_THRESHOLD)
     return two_way_short_needle ((const unsigned char *) haystack,
                                 haystack_len,
-                                (const unsigned char *) needle_start,
+                                (const unsigned char *) needle,
                                 needle_len);
   return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
-                             (const unsigned char *) needle_start,
+                             (const unsigned char *) needle,
                              needle_len);
 }