linux/init/do_mounts_rd.c at master · OneCodeMonkey/linux · GitHub

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// 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/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;

static int __init prompt_ramdisk(char *str)

{

pr_warn("ignoring the deprecated prompt_ramdisk= option\n");

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(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(char *from)

{

int res = 0;

unsigned long rd_blocks, devblocks;

int nblocks, i;

char *buf = NULL;

unsigned short rotate = 0;

decompress_fn decompressor = NULL;

#if !defined(CONFIG_S390)

char rotator[4] = { '|' , '/' , '-' , '\\' };

#endif

out_file = filp_open("/dev/ram", O_RDWR, 0);

if (IS_ERR(out_file))

goto out;

in_file = filp_open(from, 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

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

devblocks = nblocks;

else

devblocks = nr_blocks(in_file);

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; 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 !defined(CONFIG_S390)

if (!(i % 16)) {

pr_cont("%c\b", rotator[rotate & 0x3]);

rotate++;

}

#endif

}

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;

}

int __init rd_load_disk(int n)

{

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 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;

}

linux/init/do_mounts_rd.c at master · OneCodeMonkey/linux · GitHub

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