1  /* Common definition for tst-cancel4_* tests.
       2  
       3     Copyright (C) 2016-2023 Free Software Foundation, Inc.
       4     This file is part of the GNU C Library.
       5  
       6     The GNU C Library is free software; you can redistribute it and/or
       7     modify it under the terms of the GNU Lesser General Public
       8     License as published by the Free Software Foundation; either
       9     version 2.1 of the License, or (at your option) any later version.
      10  
      11     The GNU C Library is distributed in the hope that it will be useful,
      12     but WITHOUT ANY WARRANTY; without even the implied warranty of
      13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14     Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public
      17     License along with the GNU C Library; if not, see
      18     <https://www.gnu.org/licenses/>.  */
      19  
      20  #include <pthread.h>
      21  
      22  #include <support/check.h>
      23  #include <support/xthread.h>
      24  #include <support/xunistd.h>
      25  
      26  /* Pipe descriptors.  */
      27  static int fds[2];
      28  
      29  /* Temporary file descriptor, to be closed after each round.  */
      30  static int tempfd = -1;
      31  static int tempfd2 = -1;
      32  /* Name of temporary file to be removed after each round.  */
      33  static char *tempfname;
      34  /* Temporary message queue.  */
      35  static int tempmsg = -1;
      36  
      37  /* Often used barrier for two threads.  */
      38  static pthread_barrier_t b2;
      39  
      40  /* The WRITE_BUFFER_SIZE value needs to be chosen such that if we set
      41     the socket send buffer size to '1', a write of this size on that
      42     socket will block.
      43  
      44     The Linux kernel imposes a minimum send socket buffer size which
      45     has changed over the years.  As of Linux 3.10 the value is:
      46  
      47       2 * (2048 + SKB_DATA_ALIGN(sizeof(struct sk_buff)))
      48  
      49     which is attempting to make sure that with standard MTUs,
      50     TCP can always queue up at least 2 full sized packets.
      51  
      52     Furthermore, there is logic in the socket send paths that
      53     will allow one more packet (of any size) to be queued up as
      54     long as some socket buffer space remains.   Blocking only
      55     occurs when we try to queue up a new packet and the send
      56     buffer space has already been fully consumed.
      57  
      58     Therefore we must set this value to the largest possible value of
      59     the formula above (and since it depends upon the size of "struct
      60     sk_buff", it is dependent upon machine word size etc.) plus some
      61     slack space.  */
      62  
      63  #define WRITE_BUFFER_SIZE 16384
      64  
      65  /* Set the send buffer of socket S to 1 byte so any send operation
      66     done with WRITE_BUFFER_SIZE bytes will force syscall blocking.  */
      67  static void
      68  set_socket_buffer (int s)
      69  {
      70    int val = 1;
      71    socklen_t len = sizeof (val);
      72  
      73    TEST_VERIFY_EXIT (setsockopt (s, SOL_SOCKET, SO_SNDBUF, &val,
      74  		    sizeof (val)) == 0);
      75    TEST_VERIFY_EXIT (getsockopt (s, SOL_SOCKET, SO_SNDBUF, &val, &len) == 0);
      76    TEST_VERIFY_EXIT (val < WRITE_BUFFER_SIZE);
      77    printf("got size %d\n", val);
      78  }
      79  
      80  /* Cleanup handling test.  */
      81  static int cl_called;
      82  
      83  static void
      84  cl (void *arg)
      85  {
      86    ++cl_called;
      87  }
      88  
      89  /* Named pipe used to check for blocking open.  It should be closed
      90     after the cancellation handling.  */
      91  static char fifoname[] = "/tmp/tst-cancel4-fifo-XXXXXX";
      92  static int fifofd;
      93  
      94  static void
      95  __attribute__ ((used))
      96  cl_fifo (void *arg)
      97  {
      98    ++cl_called;
      99  
     100    unlink (fifoname);
     101    close (fifofd);
     102    fifofd = -1;
     103  }
     104  
     105  struct cancel_tests
     106  {
     107    const char *name;
     108    void *(*tf) (void *);
     109    int nb;
     110    int only_early;
     111  };
     112  #define ADD_TEST(name, nbar, early) { #name, tf_##name, nbar, early }