// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/minix_fs.h>
#include <linux/ext2_fs.h>
#include <linux/romfs_fs.h>
#include <uapi/linux/cramfs_fs.h>
#include <linux/initrd.h>
#include <linux/string.h>
#include <linux/string_choices.h>
#include <linux/slab.h>

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

#include <linux/decompress/generic.h>

static struct file *in_file, *out_file;
static loff_t in_pos, out_pos;

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

static int __init ramdisk_start_setup(char *str)
{
        pr_warn("ramdisk_start= option is deprecated and will be removed soon\n");
        return kstrtoint(str, 0, &rd_image_start) == 0;
}
__setup("ramdisk_start=", ramdisk_start_setup);

static int __init crd_load(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
 *      bzip2
 *      lzma
 *      xz
 *      lzo
 *      lz4
 */
static int __init
identify_ramdisk_image(struct file *file, loff_t pos,
                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;
        int start_block = rd_image_start;

        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
         */
        pos = start_block * BLOCK_SIZE;
        kernel_read(file, buf, size, &pos);

        *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
         */
        pos = start_block * BLOCK_SIZE + 0x200;
        kernel_read(file, buf, size, &pos);

        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
         */
        pos = (start_block + 1) * BLOCK_SIZE;
        kernel_read(file, buf, size, &pos);

        /* 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:
        kfree(buf);
        return nblocks;
}

static unsigned long nr_blocks(struct file *file)
{
        struct inode *inode = file->f_mapping->host;

        if (!S_ISBLK(inode->i_mode))
                return 0;
        return i_size_read(inode) >> 10;
}

int __init rd_load_image(void)
{
        int res = 0;
        unsigned long rd_blocks, devblocks, nr_disks;
        int nblocks, i;
        char *buf = NULL;
        unsigned short rotate = 0;
        decompress_fn decompressor = NULL;
        char rotator[4] = { '|' , '/' , '-' , '\\' };

        out_file = filp_open("/dev/ram", O_RDWR, 0);
        if (IS_ERR(out_file))
                goto out;

        in_file = filp_open("/initrd.image", O_RDONLY, 0);
        if (IS_ERR(in_file))
                goto noclose_input;

        in_pos = rd_image_start * BLOCK_SIZE;
        nblocks = identify_ramdisk_image(in_file, in_pos, &decompressor);
        if (nblocks < 0)
                goto done;

        if (nblocks == 0) {
                if (crd_load(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.
         */
        rd_blocks = nr_blocks(out_file);
        if (nblocks > rd_blocks) {
                printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n",
                       nblocks, rd_blocks);
                goto done;
        }

        /*
         * OK, time to copy in the data
         */
        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;
        }

        nr_disks = (nblocks - 1) / devblocks + 1;
        pr_notice("RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
                  nblocks, nr_disks, str_plural(nr_disks));
        for (i = 0; i < nblocks; i++) {
                if (i && (i % devblocks == 0)) {
                        pr_cont("done disk #1.\n");
                        rotate = 0;
                        fput(in_file);
                        break;
                }
                kernel_read(in_file, buf, BLOCK_SIZE, &in_pos);
                kernel_write(out_file, buf, BLOCK_SIZE, &out_pos);
                if (!IS_ENABLED(CONFIG_S390) && !(i % 16)) {
                        pr_cont("%c\b", rotator[rotate & 0x3]);
                        rotate++;
                }
        }
        pr_cont("done.\n");

successful_load:
        res = 1;
done:
        fput(in_file);
noclose_input:
        fput(out_file);
out:
        kfree(buf);
        init_unlink("/dev/ram");
        return res;
}

static int exit_code;
static int decompress_error;

static long __init compr_fill(void *buf, unsigned long len)
{
        long r = kernel_read(in_file, buf, len, &in_pos);
        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 long __init compr_flush(void *window, unsigned long outcnt)
{
        long written = kernel_write(out_file, window, outcnt, &out_pos);
        if (written != outcnt) {
                if (decompress_error == 0)
                        printk(KERN_ERR
                               "RAMDISK: incomplete write (%ld != %ld)\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(decompress_fn deco)
{
        int result;

        if (!deco) {
                pr_emerg("Invalid ramdisk decompression routine.  "
                         "Select appropriate config option.\n");
                panic("Could not decompress initial ramdisk image.");
        }

        result = deco(NULL, 0, compr_fill, compr_flush, NULL, NULL, error);
        if (decompress_error)
                result = 1;
        return result;
}