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/*
* This file is part of the ZFS Event Daemon (ZED)
* for ZFS on Linux (ZoL) <http://zfsonlinux.org/>.
* Developed at Lawrence Livermore National Laboratory (LLNL-CODE-403049).
* Copyright (C) 2013-2014 Lawrence Livermore National Security, LLC.
* Refer to the ZoL 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 <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "zed_log.h"
/*
* Read up to [n] bytes from [fd] into [buf].
* Return the number of bytes read, 0 on EOF, or -1 on error.
*/
ssize_t
zed_file_read_n(int fd, void *buf, size_t n)
{
unsigned char *p;
size_t n_left;
ssize_t n_read;
p = buf;
n_left = n;
while (n_left > 0) {
if ((n_read = read(fd, p, n_left)) < 0) {
if (errno == EINTR)
continue;
else
return (-1);
} else if (n_read == 0) {
break;
}
n_left -= n_read;
p += n_read;
}
return (n - n_left);
}
/*
* Write [n] bytes from [buf] out to [fd].
* Return the number of bytes written, or -1 on error.
*/
ssize_t
zed_file_write_n(int fd, void *buf, size_t n)
{
const unsigned char *p;
size_t n_left;
ssize_t n_written;
p = buf;
n_left = n;
while (n_left > 0) {
if ((n_written = write(fd, p, n_left)) < 0) {
if (errno == EINTR)
continue;
else
return (-1);
}
n_left -= n_written;
p += n_written;
}
return (n);
}
/*
* 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);
}
/*
* 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)
{
const int maxfd_def = 256;
int errno_bak;
struct rlimit rl;
int maxfd;
int fd;
errno_bak = errno;
if (getrlimit(RLIMIT_NOFILE, &rl) < 0) {
maxfd = maxfd_def;
} else if (rl.rlim_max == RLIM_INFINITY) {
maxfd = maxfd_def;
} else {
maxfd = rl.rlim_max;
}
for (fd = lowfd; fd < maxfd; fd++)
(void) close(fd);
errno = errno_bak;
}
/*
* Set the CLOEXEC flag on file descriptor [fd] so it will be automatically
* closed upon successful execution of one of the exec functions.
* Return 0 on success, or -1 on error.
*
* FIXME: No longer needed?
*/
int
zed_file_close_on_exec(int fd)
{
int flags;
if (fd < 0) {
errno = EBADF;
return (-1);
}
flags = fcntl(fd, F_GETFD);
if (flags == -1)
return (-1);
flags |= FD_CLOEXEC;
if (fcntl(fd, F_SETFD, flags) == -1)
return (-1);
return (0);
}
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