util-linux/lib/blkdev.c

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

#ifdef HAVE_LINUX_FD_H
#include <linux/fd.h>
#endif

#ifdef HAVE_SYS_DISKLABEL_H
#include <sys/disklabel.h>
#endif

#ifdef HAVE_SYS_DISK_H
#ifdef HAVE_SYS_QUEUE_H
#include <sys/queue.h> /* for LIST_HEAD */
#endif
#include <sys/disk.h>
#endif

#include "blkdev.h"
#include "linux_version.h"

static long
blkdev_valid_offset (int fd, off_t offset) {
	char ch;

	if (lseek (fd, offset, 0) < 0)
		return 0;
	if (read (fd, &ch, 1) < 1)
		return 0;
	return 1;
}

off_t
blkdev_find_size (int fd) {
	uintmax_t high, low = 0;

	for (high = 1024; blkdev_valid_offset (fd, high); ) {
		if (high == UINTMAX_MAX)
			return -1;

		low = high;

		if (high >= UINTMAX_MAX/2)
			high = UINTMAX_MAX;
		else
			high *= 2;
	}

	while (low < high - 1)
	{
		uintmax_t mid = (low + high) / 2;

		if (blkdev_valid_offset (fd, mid))
			low = mid;
		else
			high = mid;
	}
	blkdev_valid_offset (fd, 0);
	return (low + 1);
}

/* get size in bytes */
int
blkdev_get_size(int fd, unsigned long long *bytes)
{
#ifdef DKIOCGETBLOCKCOUNT
	/* Apple Darwin */
	if (ioctl(fd, DKIOCGETBLOCKCOUNT, bytes) >= 0) {
		*bytes <<= 9;
		return 0;
	}
#endif

#ifdef BLKGETSIZE64
	{
#ifdef __linux__
		int ver = get_linux_version();

		/* kernels 2.4.15-2.4.17, had a broken BLKGETSIZE64 */
		if (ver >= KERNEL_VERSION (2,6,0) ||
		   (ver >= KERNEL_VERSION (2,4,18) && ver < KERNEL_VERSION (2,5,0)))
#endif
			if (ioctl(fd, BLKGETSIZE64, bytes) >= 0)
				return 0;
	}
#endif /* BLKGETSIZE64 */

#ifdef BLKGETSIZE
	{
		unsigned long size;

		if (ioctl(fd, BLKGETSIZE, &size) >= 0) {
			*bytes = ((unsigned long long)size << 9);
			return 0;
		}
	}

#endif /* BLKGETSIZE */

#ifdef DIOCGMEDIASIZE
	/* FreeBSD */
	if (ioctl(fd, DIOCGMEDIASIZE, bytes) >= 0)
		return 0
#endif

#ifdef FDGETPRM
	{
		struct floppy_struct this_floppy;

		if (ioctl(fd, FDGETPRM, &this_floppy) >= 0) {
			*bytes = this_floppy.size << 9;
			return 0;
		}
	}
#endif /* FDGETPRM */

#ifdef HAVE_SYS_DISKLABEL_H
	{
		/*
		 * This code works for FreeBSD 4.11 i386, except for the full device
		 * (such as /dev/ad0). It doesn't work properly for newer FreeBSD
		 * though. FreeBSD >= 5.0 should be covered by the DIOCGMEDIASIZE
		 * above however.
		 *
		 * Note that FreeBSD >= 4.0 has disk devices as unbuffered (raw,
		 * character) devices, so we need to check for S_ISCHR, too.
		 */
		int part = -1;
		struct disklabel lab;
		struct partition *pp;
		char ch;
		struct stat st;

		if ((fstat(fd, &st) >= 0) &&
		    (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode)))
			part = st.st_rdev & 7;

		if (part >= 0 && (ioctl(fd, DIOCGDINFO, (char *)&lab) >= 0)) {
			pp = &lab.d_partitions[part];
			if (pp->p_size) {
				 *bytes = pp->p_size << 9;
				 return 0;
			}
		}
	}
#endif /* HAVE_SYS_DISKLABEL_H */

	{
		struct stat st;

		if (fstat(fd, &st) == 0 && S_ISREG(st.st_mode)) {
			*bytes = st.st_size;
			return 0;
		}
		if (!S_ISBLK(st.st_mode))
			return -1;
	}

	*bytes = blkdev_find_size(fd);
	return 0;
}

/* get 512-byte sector count */
int
blkdev_get_sectors(int fd, unsigned long long *sectors)
{
	unsigned long long bytes;

	if (blkdev_get_size(fd, &bytes) == 0) {
		*sectors = (bytes >> 9);
		return 0;
	}

	return -1;
}

/* get logical sector size (default is 512)
 *
 * This is the smallest unit the storage device can
 * address. It is typically 512 bytes.
 */
int
blkdev_get_sector_size(int fd, int *sector_size)
{
#ifdef BLKSSZGET
#ifdef __linux__
	if (get_linux_version() < KERNEL_VERSION(2,3,3)) {
		*sector_size = DEFAULT_SECTOR_SIZE;
		return 0;
	}
#endif
	if (ioctl(fd, BLKSSZGET, sector_size) >= 0)
		return 0;

	return -1;
#else
	*sector_size = DEFAULT_SECTOR_SIZE;
	return 0;
#endif
}


#ifdef TEST_PROGRAM
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <err.h>
int
main(int argc, char **argv)
{
	unsigned long long bytes;
	unsigned long long sectors;
	int sector_size;
	int fd;

	if (argc != 2) {
		fprintf(stderr, "usage: %s device\n", argv[0]);
		exit(EXIT_FAILURE);
	}

	if ((fd = open(argv[1], O_RDONLY)) < 0)
		err(EXIT_FAILURE, "open %s failed", argv[1]);

	if (blkdev_get_size(fd, &bytes) < 0)
		err(EXIT_FAILURE, "blkdev_get_size() failed");
	if (blkdev_get_sectors(fd, &sectors) < 0)
		err(EXIT_FAILURE, "blkdev_get_sectors() failed");
	if (blkdev_get_sector_size(fd, &sector_size) < 0)
		err(EXIT_FAILURE, "blkdev_get_sector_size() failed");

	printf("bytes %llu\n", bytes);
	printf("sectors %llu\n", sectors);
	printf("sectorsize %d\n", sector_size);

	return EXIT_SUCCESS;
}
#endif /* TEST_PROGRAM */