source: MondoRescue/branches/3.0/mindi-busybox/util-linux/blockdev.c

/*
 * blockdev implementation for busybox
 *
 * Copyright (C) 2010 Sergey Naumov <sknaumov@gmail.com>
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */

//applet:IF_BLOCKDEV(APPLET(blockdev, _BB_DIR_SBIN, _BB_SUID_DROP))

//kbuild:lib-$(CONFIG_BLOCKDEV) += blockdev.o

//config:config BLOCKDEV
//config:   bool "blockdev"
//config:   default y
//config:   help
//config:     Performs some ioctls with block devices.

//usage:#define blockdev_trivial_usage
//usage:    "OPTION BLOCKDEV"
//usage:#define blockdev_full_usage "\n\n"
//usage:       "Options:"
//usage:     "\n    --setro     Set ro"
//usage:     "\n    --setrw     Set rw"
//usage:     "\n    --getro     Get ro"
//usage:     "\n    --getss     Get sector size"
//usage:     "\n    --getbsz    Get block size"
//usage:     "\n    --setbsz BYTES  Set block size"
//usage:     "\n    --getsize   Get device size in 512-byte sectors"
//usage:     "\n    --getsize64 Get device size in bytes"
//usage:     "\n    --flushbufs Flush buffers"
//usage:     "\n    --rereadpt  Reread partition table"


#include "libbb.h"
#include <linux/fs.h>

/*  Patch bco to compile this busybox on rhel3  */
#ifndef BLKGETSIZE64
#define BLKGETSIZE64 _IOR(0x12,114,size_t)
#endif

enum {
    ARG_NONE   = 0,
    ARG_INT    = 1,
    ARG_ULONG  = 2,
    /* Yes, BLKGETSIZE64 takes pointer to uint64_t, not ullong! */
    ARG_U64    = 3,
    ARG_MASK   = 3,

    FL_USRARG   = 4, /* argument is provided by user */
    FL_NORESULT = 8,
};

struct bdc {
    uint32_t   ioc;                       /* ioctl code */
    const char name[sizeof("flushbufs")]; /* "--setfoo" wothout "--" */
    uint8_t    flags;
    int8_t     argval;                    /* default argument value */
};

static const struct bdc bdcommands[] = {
    {
        .ioc = BLKROSET,
        .name = "setro",
        .flags = ARG_INT + FL_NORESULT,
        .argval = 1,
    },{
        .ioc = BLKROSET,
        .name = "setrw",
        .flags = ARG_INT + FL_NORESULT,
        .argval = 0,
    },{
        .ioc = BLKROGET,
        .name = "getro",
        .flags = ARG_INT,
        .argval = -1,
    },{
        .ioc = BLKSSZGET,
        .name = "getss",
        .flags = ARG_INT,
        .argval = -1,
    },{
        .ioc = BLKBSZGET,
        .name = "getbsz",
        .flags = ARG_INT,
        .argval = -1,
    },{
        .ioc = BLKBSZSET,
        .name = "setbsz",
        .flags = ARG_INT + FL_NORESULT + FL_USRARG,
        .argval = 0,
    },{
        .ioc = BLKGETSIZE,
        .name = "getsize",
        .flags = ARG_ULONG,
        .argval = -1,
    },{
        .ioc = BLKGETSIZE64,
        .name = "getsize64",
        .flags = ARG_U64,
        .argval = -1,
    },{
        .ioc = BLKFLSBUF,
        .name = "flushbufs",
        .flags = ARG_NONE + FL_NORESULT,
        .argval = 0,
    },{
        .ioc = BLKRRPART,
        .name = "rereadpt",
        .flags = ARG_NONE + FL_NORESULT,
        .argval = 0,
    }
};

static const struct bdc *find_cmd(const char *s)
{
    const struct bdc *bdcmd = bdcommands;
    if (s[0] == '-' && s[1] == '-') {
        s += 2;
        do {
            if (strcmp(s, bdcmd->name) == 0)
                return bdcmd;
            bdcmd++;
        } while (bdcmd != bdcommands + ARRAY_SIZE(bdcommands));
    }
    bb_show_usage();
}

int blockdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int blockdev_main(int argc, char **argv)
{
    const struct bdc *bdcmd;
    int fd;
    uint64_t u64;
    union {
        int i;
        unsigned long lu;
        uint64_t u64;
    } ioctl_val_on_stack;

    if ((unsigned)(argc - 3) > 1) /* must have 2 or 3 args */
        bb_show_usage();

    bdcmd = find_cmd(*++argv);

    u64 = (int)bdcmd->argval;
    if (bdcmd->flags & FL_USRARG)
        u64 = xatoi_positive(*++argv);

    if (!*++argv || argv[1])
        bb_show_usage();
    fd = xopen(*argv, O_RDONLY);

    ioctl_val_on_stack.u64 = u64;
#if BB_BIG_ENDIAN
    /* Store data properly wrt data size.
     * (1) It's no-op for little-endian.
     * (2) it's no-op for 0 and -1. Only --setro uses arg != 0 and != -1,
     * and it is ARG_INT. --setbsz USER_VAL is also ARG_INT.
     * Thus, we don't need to handle ARG_ULONG.
     */
    switch (bdcmd->flags & ARG_MASK) {
    case ARG_INT:
        ioctl_val_on_stack.i = (int)u64;
        break;
# if 0 /* unused */
    case ARG_ULONG:
        ioctl_val_on_stack.lu = (unsigned long)u64;
        break;
# endif
    }
#endif

    if (ioctl(fd, bdcmd->ioc, &ioctl_val_on_stack.u64) == -1)
        bb_simple_perror_msg_and_die(*argv);

    /* Fetch it into register(s) */
    u64 = ioctl_val_on_stack.u64;

    /* Zero- or one-extend the value if needed, then print */
    switch (bdcmd->flags & (ARG_MASK+FL_NORESULT)) {
    case ARG_INT:
        /* Smaller code when we use long long
         * (gcc tail-merges printf call)
         */
        printf("%lld\n", (long long)(int)u64);
        break;
    case ARG_ULONG:
        u64 = (unsigned long)u64;
        /* FALLTHROUGH */
    case ARG_U64:
        printf("%llu\n", (unsigned long long)u64);
        break;
    }

    if (ENABLE_FEATURE_CLEAN_UP)
        close(fd);
    return EXIT_SUCCESS;
}