socket/tst-cmsghdr-skeleton.c

   1 /* Test ancillary data header creation.
   2    Copyright (C) 2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* We use the preprocessor to generate the function/macro tests instead of
  20    using indirection because having all the macro expansions alongside
  21    each other lets the compiler warn us about suspicious pointer
  22    arithmetic across subsequent CMSG_{FIRST,NXT}HDR expansions.  */
  23
  24 #include <stdint.h>
  25
  26 #define RUN_TEST_CONCAT(suffix) run_test_##suffix
  27 #define RUN_TEST_FUNCNAME(suffix) RUN_TEST_CONCAT (suffix)
  28
  29 static void
  30 RUN_TEST_FUNCNAME (CMSG_NXTHDR_IMPL) (void)
  31 {
  32   struct msghdr m = {0};
  33   struct cmsghdr *cmsg;
  34   char cmsgbuf[3 * CMSG_SPACE (sizeof (PAYLOAD))] = {0};
  35
  36   m.msg_control = cmsgbuf;
  37   m.msg_controllen = sizeof (cmsgbuf);
  38
  39   /* First header should point to the start of the buffer.  */
  40   cmsg = CMSG_FIRSTHDR (&m);
  41   TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
  42
  43   /* If the first header length consumes the entire buffer, there is no
  44      space remaining for additional headers.  */
  45   cmsg->cmsg_len = sizeof (cmsgbuf);
  46   cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
  47   TEST_VERIFY_EXIT (cmsg == NULL);
  48
  49   /* The first header length is so big, using it would cause an overflow.  */
  50   cmsg = CMSG_FIRSTHDR (&m);
  51   TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
  52   cmsg->cmsg_len = SIZE_MAX;
  53   cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
  54   TEST_VERIFY_EXIT (cmsg == NULL);
  55
  56   /* The first header leaves just enough space to hold another header.  */
  57   cmsg = CMSG_FIRSTHDR (&m);
  58   TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
  59   cmsg->cmsg_len = sizeof (cmsgbuf) - sizeof (struct cmsghdr);
  60   cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
  61   TEST_VERIFY_EXIT (cmsg != NULL);
  62
  63   /* The first header leaves space but not enough for another header.  */
  64   cmsg = CMSG_FIRSTHDR (&m);
  65   TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
  66   cmsg->cmsg_len ++;
  67   cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
  68   TEST_VERIFY_EXIT (cmsg == NULL);
  69
  70   /* The second header leaves just enough space to hold another header.  */
  71   cmsg = CMSG_FIRSTHDR (&m);
  72   TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
  73   cmsg->cmsg_len = CMSG_LEN (sizeof (PAYLOAD));
  74   cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
  75   TEST_VERIFY_EXIT (cmsg != NULL);
  76   cmsg->cmsg_len = sizeof (cmsgbuf)
  77                    - CMSG_SPACE (sizeof (PAYLOAD)) /* First header.  */
  78                    - sizeof (struct cmsghdr);
  79   cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
  80   TEST_VERIFY_EXIT (cmsg != NULL);
  81
  82   /* The second header leaves space but not enough for another header.  */
  83   cmsg = CMSG_FIRSTHDR (&m);
  84   TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
  85   cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
  86   TEST_VERIFY_EXIT (cmsg != NULL);
  87   cmsg->cmsg_len ++;
  88   cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
  89   TEST_VERIFY_EXIT (cmsg == NULL);
  90
  91   return;
  92 }