在linux2.6内核中为什么找不到地址转换函数inet_pton的实现？在很多FreeBSD的内核中却能够找到？

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在linux2.6内核中为什么找不到inet_pton的实现？在很多FreeBSD的内核中却能够找到？
真的很疑惑，不知道这个inet_pton到底是在linux2.6内核的什么地方呢？不可能找不到的呀？FreeBSD的很多内核里却能找到。实现如下：



#if defined(LIBC_SCCS) && !defined(lint)

   19 static const char rcsid[] = "$Id: inet_pton.c,v 1.3.18.2 2005/07/28 07:38:07 marka Exp $";

   20 #endif /* LIBC_SCCS and not lint */

   21 #include <sys/cdefs.h>

   22 __FBSDID("$FreeBSD: head/sys/libkern/inet_pton.c 213103 2010-09-24 15:01:45Z attilio $");

   23 

   24 #include <sys/param.h>

   25 #include <sys/socket.h>

   26 #include <sys/systm.h>

   27 

   28 #include <netinet/in.h>

   29 

   30 #if __FreeBSD_version < 700000

   31 #define strchr index

   32 #endif

   33 

   34 /*%

   35  * WARNING: Don't even consider trying to compile this on a system where

   36  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.

   37  */

   38 

   39 static int      inet_pton4(const char *src, u_char *dst);

   40 static int      inet_pton6(const char *src, u_char *dst);

   41 

   42 /* int

   43  * inet_pton(af, src, dst)

   44  *      convert from presentation format (which usually means ASCII printable)

   45  *      to network format (which is usually some kind of binary format).

   46  * return:

   47  *      1 if the address was valid for the specified address family

   48  *      0 if the address wasn't valid (`dst' is untouched in this case)

   49  *      -1 if some other error occurred (`dst' is untouched in this case, too)

   50  * author:

   51  *      Paul Vixie, 1996.

   52  */

   53 int

   54 inet_pton(int af, const char *src, void *dst)

   55 {

   56         switch (af) {

   57         case AF_INET:

   58                 return (inet_pton4(src, dst));

   59         case AF_INET6:

   60                 return (inet_pton6(src, dst));

   61         default:

   62                 return (-1);

   63         }

   64         /* NOTREACHED */

   65 }

   66 

   67 /* int

   68  * inet_pton4(src, dst)

   69  *      like inet_aton() but without all the hexadecimal and shorthand.

   70  * return:

   71  *      1 if `src' is a valid dotted quad, else 0.

   72  * notice:

   73  *      does not touch `dst' unless it's returning 1.

   74  * author:

   75  *      Paul Vixie, 1996.

   76  */

   77 static int

   78 inet_pton4(const char *src, u_char *dst)

   79 {

   80         static const char digits[] = "0123456789";

   81         int saw_digit, octets, ch;

   82 #define NS_INADDRSZ     4

   83         u_char tmp[NS_INADDRSZ], *tp;

   84 

   85         saw_digit = 0;

   86         octets = 0;

   87         *(tp = tmp) = 0;

   88         while ((ch = *src++) != '\0') {

   89                 const char *pch;

   90 

   91                 if ((pch = strchr(digits, ch)) != NULL) {

   92                         u_int new = *tp * 10 + (pch - digits);

   93 

   94                         if (saw_digit && *tp == 0)

   95                                 return (0);

   96                         if (new > 255)

   97                                 return (0);

   98                         *tp = new;

   99                         if (!saw_digit) {

  100                                 if (++octets > 4)

  101                                         return (0);

  102                                 saw_digit = 1;

  103                         }

  104                 } else if (ch == '.' && saw_digit) {

  105                         if (octets == 4)

  106                                 return (0);

  107                         *++tp = 0;

  108                         saw_digit = 0;

  109                 } else

  110                         return (0);

  111         }

  112         if (octets < 4)

  113                 return (0);

  114         memcpy(dst, tmp, NS_INADDRSZ);

  115         return (1);

  116 }