lvm2/lib/device/dev-io.c

/*
 * Copyright (C) 2001 Sistina Software
 *
 * This file is released under the LGPL.
 */

#include "device.h"
#include "lvm-types.h"
#include "log.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/mount.h>


int dev_get_size(struct device *dev, uint64_t *size)
{
	int fd;
	long s;
	const char *name = dev_name(dev);

	log_very_verbose("Getting size of %s", name);
	if ((fd = open(name, O_RDONLY)) < 0) {
		log_sys_error("open", name);
		return 0;
	}

	/* FIXME: add 64 bit ioctl */
	if (ioctl(fd, BLKGETSIZE, &s) < 0) {
		log_sys_error("ioctl BLKGETSIZE", name);
		close(fd);
		return 0;
	}

	close(fd);
	*size = (uint64_t) s;
	return 1;
}

int dev_open(struct device *dev, int flags)
{
	const char *name = dev_name(dev);

	/* FIXME Check flags (eg is write now reqd?) */
	if (dev->fd >= 0) {
		log_error("Device '%s' has already been opened", name);
		return 0;
	}

	if ((dev->fd = open(name, flags)) < 0) {
		log_sys_error("open", name);
		return 0;
	}

	return 1;
}

int dev_close(struct device *dev)
{
	if (dev->fd < 0) {
		log_error("Attempt to close device '%s' "
			  "which is not open.", dev_name(dev));
		return 0;
	}

	if (close(dev->fd))
		log_sys_error("close", dev_name(dev));

	dev->fd = -1;

	return 1;
}

/*
 *  FIXME: factor common code out.
 */
int _read(int fd, void *buf, size_t count)
{
	size_t n = 0;
	int tot = 0;

	while (tot < count) {
		do
			n = read(fd, buf, count - tot);
		while ((n < 0) && ((errno == EINTR) || (errno == EAGAIN)));

		if (n <= 0)
			return tot ? tot : n;

		tot += n;
		buf += n;
	}

	return tot;
}

int64_t dev_read(struct device *dev, uint64_t offset,
		 int64_t len, void *buffer)
{
	const char *name = dev_name(dev);
	int fd = dev->fd;

	if (fd < 0) {
		log_err("Attempt to read an unopened device (%s).", name);
		return 0;
	}

	if (lseek(fd, offset, SEEK_SET) < 0) {
		log_sys_error("lseek", name);
		return 0;
	}

	return _read(fd, buffer, len);
}

int _write(int fd, const void *buf, size_t count)
{
	size_t n = 0;
	int tot = 0;

	while (tot < count) {
		do
			n = write(fd, buf, count - tot);
		while ((n < 0) && ((errno == EINTR) || (errno == EAGAIN)));

		if (n <= 0)
			return tot ? tot : n;

		tot += n;
		buf += n;
	}

	return tot;
}

int64_t dev_write(struct device *dev, uint64_t offset,
		  int64_t len, void *buffer)
{
	const char *name = dev_name(dev);
	int fd = dev->fd;

	if (fd < 0) {
		log_error("Attempt to write to unopened device %s", name);
		return 0;
	}

	if (lseek(fd, offset, SEEK_SET) < 0) {
		log_sys_error("lseek", name);
		return 0;
	}

	return _write(fd, buffer, len);
}

int dev_zero(struct device *dev, uint64_t offset, int64_t len)
{
	int64_t r, s;
	char buffer[4096];
	const char *name = dev_name(dev);
	int fd = dev->fd;

	if (fd < 0) {
		log_error("Attempt to zero part of an unopened device %s", 
			  name);
		return 0;
	}

	if (lseek(fd, offset, SEEK_SET) < 0) {
		log_sys_error("lseek", name);
		return 0;
	}

	memset(buffer, 0, sizeof(buffer));
	while (1) {
		s = len > sizeof(buffer) ? sizeof(buffer) : len;
		r = _write(fd, buffer, s);

		if (r <= 0)
			break;

		len -= r;
		if (!len) {
			r = 1;
			break;
		}
	}

	return (len == 0);
}