1  /* Test that dprintf returns the expected length.
       2     Copyright (C) 2023 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  #include <stdio.h>
      20  #include <string.h>
      21  #include <support/check.h>
      22  #include <sys/socket.h>
      23  #include <unistd.h>
      24  
      25  static int
      26  do_test (void)
      27  {
      28    /* Use a datagram socket to check that everything arrives in one packet.
      29       The dprintf function should perform a single write call.  */
      30    int fds[2];
      31    TEST_VERIFY_EXIT (socketpair (AF_LOCAL, SOCK_DGRAM, 0, fds) == 0);
      32  
      33    TEST_COMPARE (dprintf (fds[0], "(%d)%s[%d]", 123, "---", 4567), 14);
      34  
      35    char buf[32];
      36    ssize_t ret = read (fds[1], buf, sizeof (buf));
      37    TEST_VERIFY_EXIT (ret > 0);
      38    TEST_COMPARE_BLOB (buf, ret, "(123)---[4567]", strlen ("(123)---[4567]"));
      39  
      40    close (fds[1]);
      41    close (fds[0]);
      42    return 0;
      43  }
      44  
      45  #include <support/test-driver.c>