do_mounts_rd.c

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/*
 * Many of the syscalls used in this file expect some of the arguments
 * to be __user pointers not __kernel pointers.  To limit the sparse
 * noise, turn off sparse checking for this file.
 */
#ifdef __CHECKER__
#undef __CHECKER__
#warning "Sparse checking disabled for this file"
#endif

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/minix_fs.h>
#include <linux/ext2_fs.h>
#include <linux/romfs_fs.h>
#include <linux/cramfs_fs.h>
#include <linux/initrd.h>
#include <linux/string.h>
#include <linux/slab.h>

#include "do_mounts.h"
#include "../fs/squashfs/squashfs_fs.h"

#include <linux/decompress/generic.h>


int __initdata rd_prompt = 1;/* 1 = prompt for RAM disk, 0 = don't prompt */

static int __init prompt_ramdisk(char *str)
{
    rd_prompt = simple_strtol(str,NULL,0) & 1;
    return 1;
}
__setup("prompt_ramdisk=", prompt_ramdisk);

int __initdata rd_image_start;      /* starting block # of image */

static int __init ramdisk_start_setup(char *str)
{
    rd_image_start = simple_strtol(str,NULL,0);
    return 1;
}
__setup("ramdisk_start=", ramdisk_start_setup);

static int __init crd_load(int in_fd, int out_fd, decompress_fn deco);

/*
 * This routine tries to find a RAM disk image to load, and returns the
 * number of blocks to read for a non-compressed image, 0 if the image
 * is a compressed image, and -1 if an image with the right magic
 * numbers could not be found.
 *
 * We currently check for the following magic numbers:
 *  minix
 *  ext2
 *  romfs
 *  cramfs
 *  squashfs
 *  gzip
 */
static int __init
identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
{
    const int size = 512;
    struct minix_super_block *minixsb;
    struct romfs_super_block *romfsb;
    struct cramfs_super *cramfsb;
    struct squashfs_super_block *squashfsb;
    int nblocks = -1;
    unsigned char *buf;
    const char *compress_name;
    unsigned long n;

    buf = kmalloc(size, GFP_KERNEL);
    if (!buf)
        return -ENOMEM;

    minixsb = (struct minix_super_block *) buf;
    romfsb = (struct romfs_super_block *) buf;
    cramfsb = (struct cramfs_super *) buf;
    squashfsb = (struct squashfs_super_block *) buf;
    memset(buf, 0xe5, size);

    /*
     * Read block 0 to test for compressed kernel
     */
    sys_lseek(fd, start_block * BLOCK_SIZE, 0);
    sys_read(fd, buf, size);

    *decompressor = decompress_method(buf, size, &compress_name);
    if (compress_name) {
        printk(KERN_NOTICE "RAMDISK: %s image found at block %d\n",
               compress_name, start_block);
        if (!*decompressor)
            printk(KERN_EMERG
                   "RAMDISK: %s decompressor not configured!\n",
                   compress_name);
        nblocks = 0;
        goto done;
    }

    /* romfs is at block zero too */
    if (romfsb->word0 == ROMSB_WORD0 &&
        romfsb->word1 == ROMSB_WORD1) {
        printk(KERN_NOTICE
               "RAMDISK: romfs filesystem found at block %d\n",
               start_block);
        nblocks = (ntohl(romfsb->size)+BLOCK_SIZE-1)>>BLOCK_SIZE_BITS;
        goto done;
    }

    if (cramfsb->magic == CRAMFS_MAGIC) {
        printk(KERN_NOTICE
               "RAMDISK: cramfs filesystem found at block %d\n",
               start_block);
        nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
        goto done;
    }

    /* squashfs is at block zero too */
    if (le32_to_cpu(squashfsb->s_magic) == SQUASHFS_MAGIC) {
        printk(KERN_NOTICE
               "RAMDISK: squashfs filesystem found at block %d\n",
               start_block);
        nblocks = (le64_to_cpu(squashfsb->bytes_used) + BLOCK_SIZE - 1)
             >> BLOCK_SIZE_BITS;
        goto done;
    }

    /*
     * Read 512 bytes further to check if cramfs is padded
     */
    sys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0);
    sys_read(fd, buf, size);

    if (cramfsb->magic == CRAMFS_MAGIC) {
        printk(KERN_NOTICE
               "RAMDISK: cramfs filesystem found at block %d\n",
               start_block);
        nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
        goto done;
    }

    /*
     * Read block 1 to test for minix and ext2 superblock
     */
    sys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0);
    sys_read(fd, buf, size);

    /* Try minix */
    if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
        minixsb->s_magic == MINIX_SUPER_MAGIC2) {
        printk(KERN_NOTICE
               "RAMDISK: Minix filesystem found at block %d\n",
               start_block);
        nblocks = minixsb->s_nzones << minixsb->s_log_zone_size;
        goto done;
    }

    /* Try ext2 */
    n = ext2_image_size(buf);
    if (n) {
        printk(KERN_NOTICE
               "RAMDISK: ext2 filesystem found at block %d\n",
               start_block);
        nblocks = n;
        goto done;
    }

    printk(KERN_NOTICE
           "RAMDISK: Couldn't find valid RAM disk image starting at %d.\n",
           start_block);

done:
    sys_lseek(fd, start_block * BLOCK_SIZE, 0);
    kfree(buf);
    return nblocks;
}

int __init rd_load_image(char *from)
{
    int res = 0;
    int in_fd, out_fd;
    unsigned long rd_blocks, devblocks;
    int nblocks, i, disk;
    char *buf = NULL;
    unsigned short rotate = 0;
    decompress_fn decompressor = NULL;
#if !defined(CONFIG_S390)
    char rotator[4] = { '|' , '/' , '-' , '\\' };
#endif

    out_fd = sys_open("/dev/ram", O_RDWR, 0);
    if (out_fd < 0)
        goto out;

    in_fd = sys_open(from, O_RDONLY, 0);
    if (in_fd < 0)
        goto noclose_input;

    nblocks = identify_ramdisk_image(in_fd, rd_image_start, &decompressor);
    if (nblocks < 0)
        goto done;

    if (nblocks == 0) {
        if (crd_load(in_fd, out_fd, decompressor) == 0)
            goto successful_load;
        goto done;
    }

    /*
     * NOTE NOTE: nblocks is not actually blocks but
     * the number of kibibytes of data to load into a ramdisk.
     * So any ramdisk block size that is a multiple of 1KiB should
     * work when the appropriate ramdisk_blocksize is specified
     * on the command line.
     *
     * The default ramdisk_blocksize is 1KiB and it is generally
     * silly to use anything else, so make sure to use 1KiB
     * blocksize while generating ext2fs ramdisk-images.
     */
    if (sys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0)
        rd_blocks = 0;
    else
        rd_blocks >>= 1;

    if (nblocks > rd_blocks) {
        printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n",
               nblocks, rd_blocks);
        goto done;
    }

    /*
     * OK, time to copy in the data
     */
    if (sys_ioctl(in_fd, BLKGETSIZE, (unsigned long)&devblocks) < 0)
        devblocks = 0;
    else
        devblocks >>= 1;

    if (strcmp(from, "/initrd.image") == 0)
        devblocks = nblocks;

    if (devblocks == 0) {
        printk(KERN_ERR "RAMDISK: could not determine device size\n");
        goto done;
    }

    buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
    if (!buf) {
        printk(KERN_ERR "RAMDISK: could not allocate buffer\n");
        goto done;
    }

    printk(KERN_NOTICE "RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
        nblocks, ((nblocks-1)/devblocks)+1, nblocks>devblocks ? "s" : "");
    for (i = 0, disk = 1; i < nblocks; i++) {
        if (i && (i % devblocks == 0)) {
            printk("done disk #%d.\n", disk++);
            rotate = 0;
            if (sys_close(in_fd)) {
                printk("Error closing the disk.\n");
                goto noclose_input;
            }
            change_floppy("disk #%d", disk);
            in_fd = sys_open(from, O_RDONLY, 0);
            if (in_fd < 0)  {
                printk("Error opening disk.\n");
                goto noclose_input;
            }
            printk("Loading disk #%d... ", disk);
        }
        sys_read(in_fd, buf, BLOCK_SIZE);
        sys_write(out_fd, buf, BLOCK_SIZE);
#if !defined(CONFIG_S390)
        if (!(i % 16)) {
            printk("%c\b", rotator[rotate & 0x3]);
            rotate++;
        }
#endif
    }
    printk("done.\n");

successful_load:
    res = 1;
done:
    sys_close(in_fd);
noclose_input:
    sys_close(out_fd);
out:
    kfree(buf);
    sys_unlink("/dev/ram");
    return res;
}

int __init rd_load_disk(int n)
{
    if (rd_prompt)
        change_floppy("root floppy disk to be loaded into RAM disk");
    create_dev("/dev/root", ROOT_DEV);
    create_dev("/dev/ram", MKDEV(RAMDISK_MAJOR, n));
    return rd_load_image("/dev/root");
}

static int exit_code;
static int decompress_error;
static int crd_infd, crd_outfd;

static int __init compr_fill(void *buf, unsigned int len)
{
    int r = sys_read(crd_infd, buf, len);
    if (r < 0)
        printk(KERN_ERR "RAMDISK: error while reading compressed data");
    else if (r == 0)
        printk(KERN_ERR "RAMDISK: EOF while reading compressed data");
    return r;
}

static int __init compr_flush(void *window, unsigned int outcnt)
{
    int written = sys_write(crd_outfd, window, outcnt);
    if (written != outcnt) {
        if (decompress_error == 0)
            printk(KERN_ERR
                   "RAMDISK: incomplete write (%d != %d)\n",
                   written, outcnt);
        decompress_error = 1;
        return -1;
    }
    return outcnt;
}

static void __init error(char *x)
{
    printk(KERN_ERR "%s\n", x);
    exit_code = 1;
    decompress_error = 1;
}

static int __init crd_load(int in_fd, int out_fd, decompress_fn deco)
{
    int result;
    crd_infd = in_fd;
    crd_outfd = out_fd;
    result = deco(NULL, 0, compr_fill, compr_flush, NULL, NULL, error);
    if (decompress_error)
        result = 1;
    return result;
}