summaryrefslogtreecommitdiffstats
path: root/gl/lib/memmem.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:16:24 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:16:24 +0000
commit9221dca64f0c8b5de72727491e41cf63e902eaab (patch)
treed8cbbf520eb4b5c656a54b2e36947008dcb751ad /gl/lib/memmem.c
parentInitial commit. (diff)
downloadman-db-9221dca64f0c8b5de72727491e41cf63e902eaab.tar.xz
man-db-9221dca64f0c8b5de72727491e41cf63e902eaab.zip
Adding upstream version 2.8.5.upstream/2.8.5upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'gl/lib/memmem.c')
-rw-r--r--gl/lib/memmem.c71
1 files changed, 71 insertions, 0 deletions
diff --git a/gl/lib/memmem.c b/gl/lib/memmem.c
new file mode 100644
index 0000000..12ae24f
--- /dev/null
+++ b/gl/lib/memmem.c
@@ -0,0 +1,71 @@
+/* Copyright (C) 1991-1994, 1996-1998, 2000, 2004, 2007-2019 Free Software
+ Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ 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, 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/>. */
+
+/* This particular implementation was written by Eric Blake, 2008. */
+
+#ifndef _LIBC
+# include <config.h>
+#endif
+
+/* Specification of memmem. */
+#include <string.h>
+
+#define RETURN_TYPE void *
+#define AVAILABLE(h, h_l, j, n_l) ((j) <= (h_l) - (n_l))
+#include "str-two-way.h"
+
+/* Return the first occurrence of NEEDLE in HAYSTACK. Return HAYSTACK
+ if NEEDLE_LEN is 0, otherwise NULL if NEEDLE is not found in
+ HAYSTACK. */
+void *
+memmem (const void *haystack_start, size_t haystack_len,
+ const void *needle_start, size_t needle_len)
+{
+ /* 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. */
+ const unsigned char *haystack = (const unsigned char *) haystack_start;
+ const unsigned char *needle = (const unsigned char *) needle_start;
+
+ if (needle_len == 0)
+ /* The first occurrence of the empty string is deemed to occur at
+ the beginning of the string. */
+ return (void *) haystack;
+
+ /* Sanity check, otherwise the loop might search through the whole
+ memory. */
+ if (__builtin_expect (haystack_len < needle_len, 0))
+ return NULL;
+
+ /* Use optimizations in memchr when possible, to reduce the search
+ size of haystack using a linear algorithm with a smaller
+ coefficient. However, avoid memchr for long needles, since we
+ can often achieve sublinear performance. */
+ if (needle_len < LONG_NEEDLE_THRESHOLD)
+ {
+ haystack = memchr (haystack, *needle, haystack_len);
+ if (!haystack || __builtin_expect (needle_len == 1, 0))
+ return (void *) haystack;
+ haystack_len -= haystack - (const unsigned char *) haystack_start;
+ if (haystack_len < needle_len)
+ return NULL;
+ return two_way_short_needle (haystack, haystack_len, needle, needle_len);
+ }
+ else
+ return two_way_long_needle (haystack, haystack_len, needle, needle_len);
+}
+
+#undef LONG_NEEDLE_THRESHOLD