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/* Simple implementation of strstr for systems without it.

   This function is in the public domain.  */

/*

@deftypefn Supplemental char* strstr (const char *@var{string}, const char *@var{sub})

This function searches for the substring @var{sub} in the string

@var{string}, not including the terminating null characters.  A pointer

to the first occurrence of @var{sub} is returned, or @code{NULL} if the

substring is absent.  If @var{sub} points to a string with zero

length, the function returns @var{string}.

@end deftypefn

*/

/* FIXME:  The above description is ANSI compiliant.  This routine has not

   been validated to comply with it.  -fnf */

#include <stddef.h>

extern char *strchr (const char *, int);

extern int strncmp (const void *, const void *, size_t);

extern size_t strlen (const char *);

char *

strstr (const char *s1, const char *s2)

{

  const char *p = s1;

  const size_t len = strlen (s2);

  for (; (p = strchr (p, *s2)) != 0; p++)

    {

      if (strncmp (p, s2, len) == 0)

        return (char *)p;

    }

  return (0);

}