source: MondoRescue/branches/stable/mindi-busybox/e2fsprogs/blkid/blkid_getsize.c@ 821

/*
 * getsize.c --- get the size of a partition.
 *
 * Copyright (C) 1995, 1995 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the
 * GNU Lesser General Public License.
 * %End-Header%
 */

/* include this before sys/queues.h! */
#include "blkidP.h"

#include <stdio.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#include <fcntl.h>
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef HAVE_LINUX_FD_H
#include <linux/fd.h>
#endif
#ifdef HAVE_SYS_DISKLABEL_H
#include <sys/disklabel.h>
#include <sys/stat.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
#ifdef __linux__
#include <sys/utsname.h>
#endif

#if defined(__linux__) && defined(_IO) && !defined(BLKGETSIZE)
#define BLKGETSIZE _IO(0x12,96) /* return device size */
#endif

#if defined(__linux__) && defined(_IOR) && !defined(BLKGETSIZE64)
#define BLKGETSIZE64 _IOR(0x12,114,size_t)  /* return device size in bytes (u64 *arg) */
#endif

#ifdef APPLE_DARWIN
#define BLKGETSIZE DKIOCGETBLOCKCOUNT32
#endif /* APPLE_DARWIN */

static int valid_offset(int fd, blkid_loff_t offset)
{
    char ch;

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

/*
 * Returns the number of blocks in a partition
 */
blkid_loff_t blkid_get_dev_size(int fd)
{
    int valid_blkgetsize64 = 1;
#ifdef __linux__
    struct      utsname ut;
#endif
    unsigned long long size64;
    unsigned long size;
    blkid_loff_t high, low;
#ifdef FDGETPRM
    struct floppy_struct this_floppy;
#endif
#ifdef HAVE_SYS_DISKLABEL_H
    int part = -1;
    struct disklabel lab;
    struct partition *pp;
    char ch;
    struct stat st;
#endif /* HAVE_SYS_DISKLABEL_H */

#ifdef DKIOCGETBLOCKCOUNT   /* For Apple Darwin */
    if (ioctl(fd, DKIOCGETBLOCKCOUNT, &size64) >= 0) {
        if ((sizeof(blkid_loff_t) < sizeof(unsigned long long))
            && (size64 << 9 > 0xFFFFFFFF))
            return 0; /* EFBIG */
        return (blkid_loff_t) size64 << 9;
    }
#endif

#ifdef BLKGETSIZE64
#ifdef __linux__
    if ((uname(&ut) == 0) &&
        ((ut.release[0] == '2') && (ut.release[1] == '.') &&
         (ut.release[2] < '6') && (ut.release[3] == '.')))
        valid_blkgetsize64 = 0;
#endif
    if (valid_blkgetsize64 &&
        ioctl(fd, BLKGETSIZE64, &size64) >= 0) {
        if ((sizeof(blkid_loff_t) < sizeof(unsigned long long))
            && ((size64) > 0xFFFFFFFF))
            return 0; /* EFBIG */
        return size64;
    }
#endif

#ifdef BLKGETSIZE
    if (ioctl(fd, BLKGETSIZE, &size) >= 0)
        return (blkid_loff_t)size << 9;
#endif

#ifdef FDGETPRM
    if (ioctl(fd, FDGETPRM, &this_floppy) >= 0)
        return (blkid_loff_t)this_floppy.size << 9;
#endif
#ifdef HAVE_SYS_DISKLABEL_H
#if 0
    /*
     * This should work in theory but I haven't tested it.  Anyone
     * on a BSD system want to test this for me?  In the meantime,
     * binary search mechanism should work just fine.
     */
    if ((fstat(fd, &st) >= 0) && S_ISBLK(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)
            return pp->p_size << 9;
    }
#endif
#endif /* HAVE_SYS_DISKLABEL_H */

    /*
     * OK, we couldn't figure it out by using a specialized ioctl,
     * which is generally the best way.  So do binary search to
     * find the size of the partition.
     */
    low = 0;
    for (high = 1024; valid_offset(fd, high); high *= 2)
        low = high;
    while (low < high - 1)
    {
        const blkid_loff_t mid = (low + high) / 2;

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

#ifdef TEST_PROGRAM
int main(int argc, char **argv)
{
    blkid_loff_t bytes;
    int fd;

    if (argc < 2) {
        fprintf(stderr, "Usage: %s device\n"
            "Determine the size of a device\n", argv[0]);
        return 1;
    }

    if ((fd = open(argv[1], O_RDONLY)) < 0)
        perror(argv[0]);

    bytes = blkid_get_dev_size(fd);
    printf("Device %s has %lld 1k blocks.\n", argv[1], bytes >> 10);

    return 0;
}
#endif