libiberty/strstr.c

   1 /* Simple implementation of strstr for systems without it.
   2    This function is in the public domain.  */
   3
   4 /*
   5
   6 NAME
   7
   8         strstr -- locate first occurance of a substring
   9
  10 SYNOPSIS
  11
  12         #include <string.h>
  13
  14         char *strstr (char *s1, char *s2)
  15
  16 DESCRIPTION
  17
  18         Locates the first occurance in the string pointed to by S1 of
  19         the string pointed to by S2.  Returns a pointer to the substring
  20         found, or a NULL pointer if not found.  If S2 points to a string
  21         with zero length, the function returns S1.
  22
  23 BUGS
  24
  25 */
  26
  27
  28 /* FIXME:  The above description is ANSI compiliant.  This routine has not
  29    been validated to comply with it.  -fnf */
  30
  31 char *
  32 strstr (s1, s2)
  33   char *s1, *s2;
  34 {
  35   register char *p = s1;
  36   extern char *strchr ();
  37   extern int strncmp ();
  38 #if __GNUC__==2
  39   extern __SIZE_TYPE__ strlen ();
  40 #endif
  41   register int len = strlen (s2);
  42
  43   for (; (p = strchr (p, *s2)) != 0; p++)
  44     {
  45       if (strncmp (p, s2, len) == 0)
  46         {
  47           return (p);
  48         }
  49     }
  50   return (0);
  51 }