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4349 Serge 1 
/*
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FUNCTION
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	<>---find string segment
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INDEX
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	strstr
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ANSI_SYNOPSIS
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	#include
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	char *strstr(const char *<[s1]>, const char *<[s2]>);
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TRAD_SYNOPSIS
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	#include
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	char *strstr(<[s1]>, <[s2]>)
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	char *<[s1]>;
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	char *<[s2]>;
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DESCRIPTION
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	Locates the first occurrence in the string pointed to by <[s1]> of
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	the sequence of characters in the string pointed to by <[s2]>
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	(excluding the terminating null character).
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RETURNS
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	Returns a pointer to the located string segment, or a null
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	pointer if the string <[s2]> is not found. If <[s2]> points to
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	a string with zero length, <[s1]> is returned.
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PORTABILITY
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<> is ANSI C.
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<> requires no supporting OS subroutines.
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QUICKREF
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	strstr ansi pure
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*/
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#include
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#if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__)
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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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# include "str-two-way.h"
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#endif
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char *
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_DEFUN (strstr, (searchee, lookfor),
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	_CONST char *searchee _AND
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	_CONST char *lookfor)
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{
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#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
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  /* Less code size, but quadratic performance in the worst case.  */
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  if (*searchee == 0)
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    {
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      if (*lookfor)
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	return (char *) NULL;
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      return (char *) searchee;
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    }
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  while (*searchee)
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    {
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      size_t i;
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      i = 0;
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      while (1)
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	{
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	  if (lookfor[i] == 0)
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	    {
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	      return (char *) searchee;
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	    }
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	  if (lookfor[i] != searchee[i])
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	    {
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	      break;
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	    }
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	  i++;
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	}
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      searchee++;
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    }
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  return (char *) NULL;
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#else /* compilation for speed */
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  /* Larger code size, but guaranteed linear performance.  */
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  const char *haystack = searchee;
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  const char *needle = lookfor;
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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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  int ok = 1; /* True if NEEDLE is prefix of HAYSTACK.  */
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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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    ok &= *haystack++ == *needle++;
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  if (*needle)
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    return NULL;
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  if (ok)
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    return (char *) searchee;
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  /* Reduce the size of haystack using strchr, since it has a smaller
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     linear coefficient than the Two-Way algorithm.  */
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  needle_len = needle - lookfor;
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  haystack = strchr (searchee + 1, *lookfor);
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  if (!haystack || needle_len == 1)
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    return (char *) haystack;
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  haystack_len = (haystack > searchee + needle_len ? 1
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		  : needle_len + searchee - haystack);
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  /* Perform the search.  */
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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 *) lookfor, needle_len);
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  return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
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			      (const unsigned char *) lookfor, needle_len);
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#endif /* compilation for speed */
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}