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