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* string/Makefile (distribute): Add str-two-way.h.
2008-03-29 Eric Blake <ebb9@byu.net> Rewrite string searches to O(n) rather than O(n^2). * string/str-two-way.h: New file. For linear fixed-allocation string searching. * string/memmem.c: New implementation. * string/strstr.c: New implementation. * string/strcasestr.c: New implementation. * sysdeps/posix/getaddrinfo.c (getaddrinfo): Call _res_hconf_init
This commit is contained in:
Ulrich Drepper
@ -1,5 +1,5 @@
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/* Return the offset of one string within another.
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Copyright (C) 1994, 1996-2000, 2004 Free Software Foundation, Inc.
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Copyright (C) 1994, 1996-2000, 2004, 2008 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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@ -30,113 +30,71 @@
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# include <config.h>
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#endif
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/* Specification. */
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#include <string.h>
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#include <ctype.h>
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#include <stdbool.h>
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#include <strings.h>
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#if defined _LIBC || defined HAVE_STRING_H
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# include <string.h>
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#endif
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#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
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#ifdef _LIBC
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# include <locale/localeinfo.h>
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# define TOLOWER(c) __tolower_l ((unsigned char) c, loc)
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#else
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# define TOLOWER(c) _tolower (c)
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#endif
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typedef unsigned chartype;
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/* Two-Way algorithm. */
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#define RETURN_TYPE char *
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#define AVAILABLE(h, h_l, j, n_l) \
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(!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \
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&& ((h_l) = (j) + (n_l)))
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#define CANON_ELEMENT(c) TOLOWER (c)
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#define CMP_FUNC(p1, p2, l) \
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strncasecmp ((const char *) (p1), (const char *) (p2), l)
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#include "str-two-way.h"
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#undef strcasestr
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#undef __strcasestr
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/* Find the first occurrence of NEEDLE in HAYSTACK, using
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case-insensitive comparison. This function gives unspecified
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results in multibyte locales. */
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char *
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__strcasestr (phaystack, pneedle)
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const char *phaystack;
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const char *pneedle;
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__strcasestr (const char *haystack_start, const char *needle_start)
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{
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register const unsigned char *haystack, *needle;
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register chartype b, c;
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#ifdef _LIBC
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__locale_t loc = _NL_CURRENT_LOCALE;
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#endif
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const char *haystack = haystack_start;
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const char *needle = needle_start;
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size_t needle_len; /* Length of NEEDLE. */
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size_t haystack_len; /* Known minimum length of HAYSTACK. */
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bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
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haystack = (const unsigned char *) phaystack;
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needle = (const unsigned char *) pneedle;
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b = TOLOWER (*needle);
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if (b != '\0')
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/* Determine length of NEEDLE, and in the process, make sure
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HAYSTACK is at least as long (no point processing all of a long
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NEEDLE if HAYSTACK is too short). */
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while (*haystack && *needle)
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{
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haystack--; /* possible ANSI violation */
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do
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{
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c = *++haystack;
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if (c == '\0')
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goto ret0;
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}
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while (TOLOWER (c) != (int) b);
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c = TOLOWER (*++needle);
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if (c == '\0')
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goto foundneedle;
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++needle;
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goto jin;
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for (;;)
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{
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register chartype a;
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register const unsigned char *rhaystack, *rneedle;
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do
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{
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a = *++haystack;
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if (a == '\0')
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goto ret0;
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if (TOLOWER (a) == (int) b)
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break;
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a = *++haystack;
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if (a == '\0')
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goto ret0;
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shloop:
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;
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}
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while (TOLOWER (a) != (int) b);
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jin: a = *++haystack;
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if (a == '\0')
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goto ret0;
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if (TOLOWER (a) != (int) c)
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goto shloop;
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rhaystack = haystack-- + 1;
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rneedle = needle;
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a = TOLOWER (*rneedle);
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if (TOLOWER (*rhaystack) == (int) a)
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do
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{
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if (a == '\0')
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goto foundneedle;
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++rhaystack;
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a = TOLOWER (*++needle);
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if (TOLOWER (*rhaystack) != (int) a)
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break;
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if (a == '\0')
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goto foundneedle;
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++rhaystack;
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a = TOLOWER (*++needle);
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}
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while (TOLOWER (*rhaystack) == (int) a);
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needle = rneedle; /* took the register-poor approach */
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if (a == '\0')
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break;
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}
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ok &= (TOLOWER ((unsigned char) *haystack)
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== TOLOWER ((unsigned char) *needle));
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haystack++;
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needle++;
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}
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foundneedle:
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return (char*) haystack;
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ret0:
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return 0;
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if (*needle)
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return NULL;
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if (ok)
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return (char *) haystack_start;
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needle_len = needle - needle_start;
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haystack = haystack_start + 1;
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haystack_len = needle_len - 1;
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/* Perform the search. Abstract memory is considered to be an array
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of 'unsigned char' values, not an array of 'char' values. See
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ISO C 99 section 6.2.6.1. */
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if (needle_len < LONG_NEEDLE_THRESHOLD)
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return two_way_short_needle ((const unsigned char *) haystack,
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haystack_len,
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(const unsigned char *) needle_start,
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needle_len);
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return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
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(const unsigned char *) needle_start,
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needle_len);
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}
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#undef LONG_NEEDLE_THRESHOLD
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weak_alias (__strcasestr, strcasestr)
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