libiberty/strstr.c

   1 /* Simple implementation of strstr for systems without it.
   2    This function is in the public domain.  */
   3
   4 /*
   5
   6 @deftypefn Supplemental char* strstr (const char *@var{string}, const char *@var{sub})
   7
   8 This function searches for the substring @var{sub} in the string
   9 @var{string}, not including the terminating null characters.  A pointer
  10 to the first occurrence of @var{sub} is returned, or @code{NULL} if the
  11 substring is absent.  If @var{sub} points to a string with zero
  12 length, the function returns @var{string}.
  13
  14 @end deftypefn
  15
  16
  17 */
  18
  19 #include <stddef.h>
  20
  21 extern int memcmp (const void *, const void *, size_t);
  22 extern size_t strlen (const char *);
  23
  24 char *
  25 strstr (const char *s1, const char *s2)
  26 {
  27   const size_t len = strlen (s2);
  28   while (*s1)
  29     {
  30       if (!memcmp (s1, s2, len))
  31         return (char *)s1;
  32       ++s1;
  33     }
  34   return (0);
  35 }