sysdeps/unix/sysv/linux/recvmsg.c

   1 /* Copyright (C) 1998 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <sys/socket.h>
  20 #include <errno.h>
  21 #include <string.h>
  22
  23 #include <asm/posix_types.h>
  24
  25 /* The kernel expects this structure in SCM_CREDS messages.
  26  * Note: sizeof(struct __kernel_ucred) <= sizeof(struct cmsgcred) must hold.
  27  */
  28 struct __kernel_ucred
  29 {
  30   __kernel_pid_t pid;
  31   __kernel_uid_t uid;
  32   __kernel_gid_t gid;
  33 };
  34
  35 extern int __syscall_recvmsg (int, struct msghdr *, int);
  36
  37 int
  38 __libc_recvmsg (int fd, struct msghdr *message, int flags)
  39 {
  40   struct cmsghdr *cm;
  41   int ret;
  42
  43   ret = __syscall_recvmsg (fd, message, flags);
  44
  45   if (ret == -1)
  46     return ret;
  47
  48   /* Postprocess the message control block for SCM_CREDS.  */
  49   cm = CMSG_FIRSTHDR (message);
  50   while (cm)
  51     {
  52       if (cm->cmsg_type == SCM_CREDS)
  53         {
  54           struct cmsgcred *c = (struct cmsgcred *) CMSG_DATA (cm);
  55           struct __kernel_ucred u;
  56           int i;
  57           memcpy (&u, CMSG_DATA (cm), sizeof (struct __kernel_ucred));
  58
  59           c->cmcred_pid = u.pid;
  60           c->cmcred_uid = u.uid;
  61           c->cmcred_gid = u.gid;
  62
  63           c->cmcred_euid = -1;
  64           c->cmcred_ngroups = 0;
  65           for (i = 0; i < CMGROUP_MAX; i++)
  66             c->cmcred_groups[i] = -1;
  67         }
  68       cm = CMSG_NXTHDR (message, cm);
  69     }
  70
  71   return ret;
  72 }
  73
  74 weak_alias (__libc_recvmsg, recvmsg)