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/* Tests for support_open_dev_null_range.
Copyright (C) 2021-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <dirent.h>
#include <fcntl.h>
#include <limits.h>
#include <support/check.h>
#include <support/support.h>
#include <support/xunistd.h>
#include <sys/resource.h>
#include <stdlib.h>
#ifndef PATH_MAX
# define PATH_MAX 1024
#endif
#include <stdio.h>
static void
check_path (int fd)
{
char *proc_fd_path = xasprintf ("/proc/self/fd/%d", fd);
char file_path[PATH_MAX];
ssize_t file_path_length
= readlink (proc_fd_path, file_path, sizeof (file_path));
if (file_path_length < 0)
FAIL_EXIT1 ("readlink (%s, %p, %zu)", proc_fd_path, file_path,
sizeof (file_path));
free (proc_fd_path);
file_path[file_path_length] = '\0';
TEST_COMPARE_STRING (file_path, "/dev/null");
}
static int
number_of_opened_files (void)
{
DIR *fds = opendir ("/proc/self/fd");
if (fds == NULL)
FAIL_EXIT1 ("opendir (\"/proc/self/fd\"): %m");
int r = 0;
while (true)
{
errno = 0;
struct dirent64 *e = readdir64 (fds);
if (e == NULL)
{
if (errno != 0)
FAIL_EXIT1 ("readdir: %m");
break;
}
if (e->d_name[0] == '.')
continue;
char *endptr;
long int fd = strtol (e->d_name, &endptr, 10);
if (*endptr != '\0' || fd < 0 || fd > INT_MAX)
FAIL_EXIT1 ("readdir: invalid file descriptor name: /proc/self/fd/%s",
e->d_name);
/* Skip the descriptor which is used to enumerate the
descriptors. */
if (fd == dirfd (fds))
continue;
r = r + 1;
}
closedir (fds);
return r;
}
static int
do_test (void)
{
const int nfds1 = 8;
int lowfd = support_open_dev_null_range (nfds1, O_RDONLY, 0600);
for (int i = 0; i < nfds1; i++)
{
TEST_VERIFY (fcntl (lowfd + i, F_GETFL) > -1);
check_path (lowfd + i);
}
/* create some gaps. */
xclose (lowfd + 1);
xclose (lowfd + 5);
xclose (lowfd + 6);
const int nfds2 = 16;
int lowfd2 = support_open_dev_null_range (nfds2, O_RDONLY, 0600);
for (int i = 0; i < nfds2; i++)
{
TEST_VERIFY (fcntl (lowfd2 + i, F_GETFL) > -1);
check_path (lowfd2 + i);
}
/* Decrease the maximum number of files. */
{
struct rlimit rl;
if (getrlimit (RLIMIT_NOFILE, &rl) == -1)
FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
rl.rlim_cur = number_of_opened_files ();
if (setrlimit (RLIMIT_NOFILE, &rl) == 1)
FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m");
}
const int nfds3 = 16;
int lowfd3 = support_open_dev_null_range (nfds3, O_RDONLY, 0600);
for (int i = 0; i < nfds3; i++)
{
TEST_VERIFY (fcntl (lowfd3 + i, F_GETFL) > -1);
check_path (lowfd3 + i);
}
/* create a lot of gaps to trigger the range extension. */
xclose (lowfd3 + 1);
xclose (lowfd3 + 3);
xclose (lowfd3 + 5);
xclose (lowfd3 + 7);
xclose (lowfd3 + 9);
xclose (lowfd3 + 11);
xclose (lowfd3 + 13);
const int nfds4 = 16;
int lowfd4 = support_open_dev_null_range (nfds4, O_RDONLY, 0600);
for (int i = 0; i < nfds4; i++)
{
TEST_VERIFY (fcntl (lowfd4 + i, F_GETFL) > -1);
check_path (lowfd4 + i);
}
return 0;
}
#include <support/test-driver.c>
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