379 lines
9.9 KiB
C
379 lines
9.9 KiB
C
/***
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/resource.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "dirent-util.h"
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#include "fd-util.h"
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#include "fs-util.h"
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#include "macro.h"
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#include "missing.h"
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#include "parse-util.h"
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#include "path-util.h"
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#include "socket-util.h"
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#include "stdio-util.h"
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#include "util.h"
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int close_nointr(int fd) {
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assert(fd >= 0);
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if (close(fd) >= 0)
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return 0;
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/*
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* Just ignore EINTR; a retry loop is the wrong thing to do on
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* Linux.
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*
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* http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html
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* https://bugzilla.gnome.org/show_bug.cgi?id=682819
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* http://utcc.utoronto.ca/~cks/space/blog/unix/CloseEINTR
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* https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain
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*/
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if (errno == EINTR)
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return 0;
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return -errno;
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}
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int safe_close(int fd) {
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/*
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* Like close_nointr() but cannot fail. Guarantees errno is
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* unchanged. Is a NOP with negative fds passed, and returns
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* -1, so that it can be used in this syntax:
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*
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* fd = safe_close(fd);
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*/
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if (fd >= 0) {
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PROTECT_ERRNO;
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/* The kernel might return pretty much any error code
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* via close(), but the fd will be closed anyway. The
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* only condition we want to check for here is whether
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* the fd was invalid at all... */
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assert_se(close_nointr(fd) != -EBADF);
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}
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return -1;
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}
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void safe_close_pair(int p[]) {
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assert(p);
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if (p[0] == p[1]) {
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/* Special case pairs which use the same fd in both
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* directions... */
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p[0] = p[1] = safe_close(p[0]);
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return;
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}
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p[0] = safe_close(p[0]);
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p[1] = safe_close(p[1]);
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}
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void close_many(const int fds[], unsigned n_fd) {
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unsigned i;
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assert(fds || n_fd <= 0);
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for (i = 0; i < n_fd; i++)
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safe_close(fds[i]);
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}
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int fclose_nointr(FILE *f) {
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assert(f);
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/* Same as close_nointr(), but for fclose() */
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if (fclose(f) == 0)
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return 0;
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if (errno == EINTR)
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return 0;
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return -errno;
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}
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FILE* safe_fclose(FILE *f) {
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/* Same as safe_close(), but for fclose() */
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if (f) {
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PROTECT_ERRNO;
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assert_se(fclose_nointr(f) != EBADF);
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}
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return NULL;
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}
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DIR* safe_closedir(DIR *d) {
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if (d) {
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PROTECT_ERRNO;
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assert_se(closedir(d) >= 0 || errno != EBADF);
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}
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return NULL;
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}
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int fd_nonblock(int fd, bool nonblock) {
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int flags, nflags;
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assert(fd >= 0);
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flags = fcntl(fd, F_GETFL, 0);
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if (flags < 0)
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return -errno;
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if (nonblock)
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nflags = flags | O_NONBLOCK;
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else
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nflags = flags & ~O_NONBLOCK;
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if (nflags == flags)
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return 0;
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if (fcntl(fd, F_SETFL, nflags) < 0)
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return -errno;
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return 0;
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}
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int fd_cloexec(int fd, bool cloexec) {
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int flags, nflags;
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assert(fd >= 0);
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flags = fcntl(fd, F_GETFD, 0);
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if (flags < 0)
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return -errno;
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if (cloexec)
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nflags = flags | FD_CLOEXEC;
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else
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nflags = flags & ~FD_CLOEXEC;
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if (nflags == flags)
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return 0;
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if (fcntl(fd, F_SETFD, nflags) < 0)
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return -errno;
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return 0;
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}
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void stdio_unset_cloexec(void) {
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fd_cloexec(STDIN_FILENO, false);
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fd_cloexec(STDOUT_FILENO, false);
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fd_cloexec(STDERR_FILENO, false);
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}
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_pure_ static bool fd_in_set(int fd, const int fdset[], unsigned n_fdset) {
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unsigned i;
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assert(n_fdset == 0 || fdset);
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for (i = 0; i < n_fdset; i++)
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if (fdset[i] == fd)
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return true;
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return false;
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}
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int close_all_fds(const int except[], unsigned n_except) {
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_cleanup_closedir_ DIR *d = NULL;
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struct dirent *de;
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int r = 0;
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assert(n_except == 0 || except);
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d = opendir("/proc/self/fd");
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if (!d) {
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int fd;
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struct rlimit rl;
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/* When /proc isn't available (for example in chroots)
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* the fallback is brute forcing through the fd
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* table */
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assert_se(getrlimit(RLIMIT_NOFILE, &rl) >= 0);
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for (fd = 3; fd < (int) rl.rlim_max; fd ++) {
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if (fd_in_set(fd, except, n_except))
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continue;
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if (close_nointr(fd) < 0)
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if (errno != EBADF && r == 0)
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r = -errno;
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}
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return r;
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}
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FOREACH_DIRENT(de, d, return -errno) {
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int fd = -1;
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if (safe_atoi(de->d_name, &fd) < 0)
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/* Let's better ignore this, just in case */
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continue;
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if (fd < 3)
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continue;
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if (fd == dirfd(d))
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continue;
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if (fd_in_set(fd, except, n_except))
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continue;
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if (close_nointr(fd) < 0) {
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/* Valgrind has its own FD and doesn't want to have it closed */
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if (errno != EBADF && r == 0)
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r = -errno;
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}
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}
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return r;
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}
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int same_fd(int a, int b) {
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struct stat sta, stb;
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pid_t pid;
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int r, fa, fb;
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assert(a >= 0);
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assert(b >= 0);
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/* Compares two file descriptors. Note that semantics are
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* quite different depending on whether we have kcmp() or we
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* don't. If we have kcmp() this will only return true for
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* dup()ed file descriptors, but not otherwise. If we don't
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* have kcmp() this will also return true for two fds of the same
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* file, created by separate open() calls. Since we use this
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* call mostly for filtering out duplicates in the fd store
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* this difference hopefully doesn't matter too much. */
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if (a == b)
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return true;
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/* Try to use kcmp() if we have it. */
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pid = getpid();
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r = kcmp(pid, pid, KCMP_FILE, a, b);
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if (r == 0)
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return true;
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if (r > 0)
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return false;
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if (errno != ENOSYS)
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return -errno;
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/* We don't have kcmp(), use fstat() instead. */
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if (fstat(a, &sta) < 0)
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return -errno;
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if (fstat(b, &stb) < 0)
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return -errno;
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if ((sta.st_mode & S_IFMT) != (stb.st_mode & S_IFMT))
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return false;
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/* We consider all device fds different, since two device fds
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* might refer to quite different device contexts even though
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* they share the same inode and backing dev_t. */
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if (S_ISCHR(sta.st_mode) || S_ISBLK(sta.st_mode))
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return false;
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if (sta.st_dev != stb.st_dev || sta.st_ino != stb.st_ino)
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return false;
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/* The fds refer to the same inode on disk, let's also check
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* if they have the same fd flags. This is useful to
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* distinguish the read and write side of a pipe created with
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* pipe(). */
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fa = fcntl(a, F_GETFL);
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if (fa < 0)
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return -errno;
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fb = fcntl(b, F_GETFL);
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if (fb < 0)
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return -errno;
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return fa == fb;
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}
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void cmsg_close_all(struct msghdr *mh) {
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struct cmsghdr *cmsg;
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assert(mh);
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CMSG_FOREACH(cmsg, mh)
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if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
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close_many((int*) CMSG_DATA(cmsg), (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int));
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}
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bool fdname_is_valid(const char *s) {
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const char *p;
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/* Validates a name for $LISTEN_FDNAMES. We basically allow
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* everything ASCII that's not a control character. Also, as
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* special exception the ":" character is not allowed, as we
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* use that as field separator in $LISTEN_FDNAMES.
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*
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* Note that the empty string is explicitly allowed
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* here. However, we limit the length of the names to 255
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* characters. */
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if (!s)
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return false;
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for (p = s; *p; p++) {
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if (*p < ' ')
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return false;
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if (*p >= 127)
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return false;
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if (*p == ':')
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return false;
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}
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return p - s < 256;
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}
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int fd_get_path(int fd, char **ret) {
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char procfs_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
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int r;
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xsprintf(procfs_path, "/proc/self/fd/%i", fd);
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r = readlink_malloc(procfs_path, ret);
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if (r == -ENOENT) /* If the file doesn't exist the fd is invalid */
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return -EBADF;
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return r;
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}
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