misc/tst-fd_to_filename.c

   1 /* Test for /proc/self/fd (or /dev/fd) pathname construction.
   2    Copyright (C) 2020-2024 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 <fcntl.h>
  20 #include <fd_to_filename.h>
  21 #include <stdio.h>
  22 #include <support/check.h>
  23 #include <support/xunistd.h>
  24
  25 /* Run a check on one value.  */
  26 static void
  27 check (int value)
  28 {
  29   if (value < 0)
  30     /* Negative descriptor values violate the precondition.  */
  31     return;
  32
  33   struct fd_to_filename storage;
  34   char *actual = __fd_to_filename (value, &storage);
  35   char expected[100];
  36   snprintf (expected, sizeof (expected), FD_TO_FILENAME_PREFIX "%d", value);
  37   TEST_COMPARE_STRING (actual, expected);
  38 }
  39
  40 /* Check various ranges constructed around powers.  */
  41 static void
  42 check_ranges (int base)
  43 {
  44   unsigned int power = 1;
  45   do
  46     {
  47       for (int factor = 1; factor < base; ++factor)
  48         for (int shift = -1000; shift <= 1000; ++shift)
  49           check (factor * power + shift);
  50     }
  51   while (!__builtin_mul_overflow (power, base, &power));
  52 }
  53
  54 /* Check that it is actually possible to use a the constructed
  55    name.  */
  56 static void
  57 check_open (void)
  58 {
  59   int pipes[2];
  60   xpipe (pipes);
  61
  62   struct fd_to_filename storage;
  63   int read_alias = xopen (__fd_to_filename (pipes[0], &storage), O_RDONLY, 0);
  64   int write_alias = xopen (__fd_to_filename (pipes[1], &storage), O_WRONLY, 0);
  65
  66   /* Ensure that all the descriptor numbers are different.  */
  67   TEST_VERIFY (pipes[0] < pipes[1]);
  68   TEST_VERIFY (pipes[1] < read_alias);
  69   TEST_VERIFY (read_alias < write_alias);
  70
  71   xwrite (write_alias, "1", 1);
  72   char buf[16];
  73   TEST_COMPARE_BLOB ("1", 1, buf, read (pipes[0], buf, sizeof (buf)));
  74
  75   xwrite (pipes[1], "2", 1);
  76   TEST_COMPARE_BLOB ("2", 1, buf, read (read_alias, buf, sizeof (buf)));
  77
  78   xwrite (write_alias, "3", 1);
  79   TEST_COMPARE_BLOB ("3", 1, buf, read (read_alias, buf, sizeof (buf)));
  80
  81   xwrite (pipes[1], "4", 1);
  82   TEST_COMPARE_BLOB ("4", 1, buf, read (pipes[0], buf, sizeof (buf)));
  83
  84   xclose (write_alias);
  85   xclose (read_alias);
  86   xclose (pipes[1]);
  87   xclose (pipes[0]);
  88 }
  89
  90 static int
  91 do_test (void)
  92 {
  93   check_ranges (2);
  94   check_ranges (10);
  95
  96   check_open ();
  97
  98   return 0;
  99 }
 100
 101 #include <support/test-driver.c>