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9530eb64e0
Sponsored-by: https://despairlabs.com/sponsor/ Signed-off-by: Rob Norris <robn@despairlabs.com> Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
143 lines
3.0 KiB
C
143 lines
3.0 KiB
C
// SPDX-License-Identifier: CDDL-1.0
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/*
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* This file is part of the ZFS Event Daemon (ZED).
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*
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* Developed at Lawrence Livermore National Laboratory (LLNL-CODE-403049).
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* Copyright (C) 2013-2014 Lawrence Livermore National Security, LLC.
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* Refer to the OpenZFS git commit log for authoritative copyright attribution.
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License Version 1.0 (CDDL-1.0).
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* You can obtain a copy of the license from the top-level file
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* "OPENSOLARIS.LICENSE" or at <http://opensource.org/licenses/CDDL-1.0>.
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* You may not use this file except in compliance with the license.
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*/
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "zed_file.h"
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#include "zed_log.h"
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/*
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* Set an exclusive advisory lock on the open file descriptor [fd].
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* Return 0 on success, 1 if a conflicting lock is held by another process,
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* or -1 on error (with errno set).
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*/
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int
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zed_file_lock(int fd)
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{
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struct flock lock;
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if (fd < 0) {
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errno = EBADF;
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return (-1);
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}
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lock.l_type = F_WRLCK;
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lock.l_whence = SEEK_SET;
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lock.l_start = 0;
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lock.l_len = 0;
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if (fcntl(fd, F_SETLK, &lock) < 0) {
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if ((errno == EACCES) || (errno == EAGAIN))
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return (1);
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return (-1);
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}
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return (0);
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}
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/*
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* Release an advisory lock held on the open file descriptor [fd].
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* Return 0 on success, or -1 on error (with errno set).
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*/
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int
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zed_file_unlock(int fd)
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{
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struct flock lock;
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if (fd < 0) {
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errno = EBADF;
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return (-1);
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}
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lock.l_type = F_UNLCK;
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lock.l_whence = SEEK_SET;
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lock.l_start = 0;
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lock.l_len = 0;
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if (fcntl(fd, F_SETLK, &lock) < 0)
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return (-1);
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return (0);
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}
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/*
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* Test whether an exclusive advisory lock could be obtained for the open
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* file descriptor [fd].
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* Return 0 if the file is not locked, >0 for the PID of another process
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* holding a conflicting lock, or -1 on error (with errno set).
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*/
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pid_t
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zed_file_is_locked(int fd)
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{
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struct flock lock;
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if (fd < 0) {
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errno = EBADF;
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return (-1);
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}
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lock.l_type = F_WRLCK;
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lock.l_whence = SEEK_SET;
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lock.l_start = 0;
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lock.l_len = 0;
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if (fcntl(fd, F_GETLK, &lock) < 0)
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return (-1);
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if (lock.l_type == F_UNLCK)
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return (0);
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return (lock.l_pid);
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}
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#if __APPLE__
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#define PROC_SELF_FD "/dev/fd"
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#else /* Linux-compatible layout */
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#define PROC_SELF_FD "/proc/self/fd"
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#endif
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/*
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* Close all open file descriptors greater than or equal to [lowfd].
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* Any errors encountered while closing file descriptors are ignored.
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*/
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void
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zed_file_close_from(int lowfd)
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{
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int errno_bak = errno;
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int maxfd = 0;
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int fd;
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DIR *fddir;
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struct dirent *fdent;
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if ((fddir = opendir(PROC_SELF_FD)) != NULL) {
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while ((fdent = readdir(fddir)) != NULL) {
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fd = atoi(fdent->d_name);
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if (fd > maxfd && fd != dirfd(fddir))
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maxfd = fd;
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}
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(void) closedir(fddir);
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} else {
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maxfd = sysconf(_SC_OPEN_MAX);
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}
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for (fd = lowfd; fd < maxfd; fd++)
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(void) close(fd);
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errno = errno_bak;
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}
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