Root/init/do_mounts_rd.c

1/*
2 * Many of the syscalls used in this file expect some of the arguments
3 * to be __user pointers not __kernel pointers. To limit the sparse
4 * noise, turn off sparse checking for this file.
5 */
6#ifdef __CHECKER__
7#undef __CHECKER__
8#warning "Sparse checking disabled for this file"
9#endif
10
11#include <linux/kernel.h>
12#include <linux/fs.h>
13#include <linux/minix_fs.h>
14#include <linux/ext2_fs.h>
15#include <linux/romfs_fs.h>
16#include <linux/cramfs_fs.h>
17#include <linux/initrd.h>
18#include <linux/string.h>
19#include <linux/slab.h>
20
21#include "do_mounts.h"
22#include "../fs/squashfs/squashfs_fs.h"
23
24#include <linux/decompress/generic.h>
25
26
27int __initdata rd_prompt = 1;/* 1 = prompt for RAM disk, 0 = don't prompt */
28
29static int __init prompt_ramdisk(char *str)
30{
31    rd_prompt = simple_strtol(str,NULL,0) & 1;
32    return 1;
33}
34__setup("prompt_ramdisk=", prompt_ramdisk);
35
36int __initdata rd_image_start; /* starting block # of image */
37
38static int __init ramdisk_start_setup(char *str)
39{
40    rd_image_start = simple_strtol(str,NULL,0);
41    return 1;
42}
43__setup("ramdisk_start=", ramdisk_start_setup);
44
45static int __init crd_load(int in_fd, int out_fd, decompress_fn deco);
46
47/*
48 * This routine tries to find a RAM disk image to load, and returns the
49 * number of blocks to read for a non-compressed image, 0 if the image
50 * is a compressed image, and -1 if an image with the right magic
51 * numbers could not be found.
52 *
53 * We currently check for the following magic numbers:
54 * minix
55 * ext2
56 * romfs
57 * cramfs
58 * squashfs
59 * gzip
60 */
61static int __init
62identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
63{
64    const int size = 512;
65    struct minix_super_block *minixsb;
66    struct romfs_super_block *romfsb;
67    struct cramfs_super *cramfsb;
68    struct squashfs_super_block *squashfsb;
69    int nblocks = -1;
70    unsigned char *buf;
71    const char *compress_name;
72    unsigned long n;
73
74    buf = kmalloc(size, GFP_KERNEL);
75    if (!buf)
76        return -ENOMEM;
77
78    minixsb = (struct minix_super_block *) buf;
79    romfsb = (struct romfs_super_block *) buf;
80    cramfsb = (struct cramfs_super *) buf;
81    squashfsb = (struct squashfs_super_block *) buf;
82    memset(buf, 0xe5, size);
83
84    /*
85     * Read block 0 to test for compressed kernel
86     */
87    sys_lseek(fd, start_block * BLOCK_SIZE, 0);
88    sys_read(fd, buf, size);
89
90    *decompressor = decompress_method(buf, size, &compress_name);
91    if (compress_name) {
92        printk(KERN_NOTICE "RAMDISK: %s image found at block %d\n",
93               compress_name, start_block);
94        if (!*decompressor)
95            printk(KERN_EMERG
96                   "RAMDISK: %s decompressor not configured!\n",
97                   compress_name);
98        nblocks = 0;
99        goto done;
100    }
101
102    /* romfs is at block zero too */
103    if (romfsb->word0 == ROMSB_WORD0 &&
104        romfsb->word1 == ROMSB_WORD1) {
105        printk(KERN_NOTICE
106               "RAMDISK: romfs filesystem found at block %d\n",
107               start_block);
108        nblocks = (ntohl(romfsb->size)+BLOCK_SIZE-1)>>BLOCK_SIZE_BITS;
109        goto done;
110    }
111
112    if (cramfsb->magic == CRAMFS_MAGIC) {
113        printk(KERN_NOTICE
114               "RAMDISK: cramfs filesystem found at block %d\n",
115               start_block);
116        nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
117        goto done;
118    }
119
120    /* squashfs is at block zero too */
121    if (le32_to_cpu(squashfsb->s_magic) == SQUASHFS_MAGIC) {
122        printk(KERN_NOTICE
123               "RAMDISK: squashfs filesystem found at block %d\n",
124               start_block);
125        nblocks = (le64_to_cpu(squashfsb->bytes_used) + BLOCK_SIZE - 1)
126             >> BLOCK_SIZE_BITS;
127        goto done;
128    }
129
130    /*
131     * Read 512 bytes further to check if cramfs is padded
132     */
133    sys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0);
134    sys_read(fd, buf, size);
135
136    if (cramfsb->magic == CRAMFS_MAGIC) {
137        printk(KERN_NOTICE
138               "RAMDISK: cramfs filesystem found at block %d\n",
139               start_block);
140        nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
141        goto done;
142    }
143
144    /*
145     * Read block 1 to test for minix and ext2 superblock
146     */
147    sys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0);
148    sys_read(fd, buf, size);
149
150    /* Try minix */
151    if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
152        minixsb->s_magic == MINIX_SUPER_MAGIC2) {
153        printk(KERN_NOTICE
154               "RAMDISK: Minix filesystem found at block %d\n",
155               start_block);
156        nblocks = minixsb->s_nzones << minixsb->s_log_zone_size;
157        goto done;
158    }
159
160    /* Try ext2 */
161    n = ext2_image_size(buf);
162    if (n) {
163        printk(KERN_NOTICE
164               "RAMDISK: ext2 filesystem found at block %d\n",
165               start_block);
166        nblocks = n;
167        goto done;
168    }
169
170    printk(KERN_NOTICE
171           "RAMDISK: Couldn't find valid RAM disk image starting at %d.\n",
172           start_block);
173
174done:
175    sys_lseek(fd, start_block * BLOCK_SIZE, 0);
176    kfree(buf);
177    return nblocks;
178}
179
180int __init rd_load_image(char *from)
181{
182    int res = 0;
183    int in_fd, out_fd;
184    unsigned long rd_blocks, devblocks;
185    int nblocks, i, disk;
186    char *buf = NULL;
187    unsigned short rotate = 0;
188    decompress_fn decompressor = NULL;
189#if !defined(CONFIG_S390)
190    char rotator[4] = { '|' , '/' , '-' , '\\' };
191#endif
192
193    out_fd = sys_open("/dev/ram", O_RDWR, 0);
194    if (out_fd < 0)
195        goto out;
196
197    in_fd = sys_open(from, O_RDONLY, 0);
198    if (in_fd < 0)
199        goto noclose_input;
200
201    nblocks = identify_ramdisk_image(in_fd, rd_image_start, &decompressor);
202    if (nblocks < 0)
203        goto done;
204
205    if (nblocks == 0) {
206        if (crd_load(in_fd, out_fd, decompressor) == 0)
207            goto successful_load;
208        goto done;
209    }
210
211    /*
212     * NOTE NOTE: nblocks is not actually blocks but
213     * the number of kibibytes of data to load into a ramdisk.
214     * So any ramdisk block size that is a multiple of 1KiB should
215     * work when the appropriate ramdisk_blocksize is specified
216     * on the command line.
217     *
218     * The default ramdisk_blocksize is 1KiB and it is generally
219     * silly to use anything else, so make sure to use 1KiB
220     * blocksize while generating ext2fs ramdisk-images.
221     */
222    if (sys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0)
223        rd_blocks = 0;
224    else
225        rd_blocks >>= 1;
226
227    if (nblocks > rd_blocks) {
228        printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n",
229               nblocks, rd_blocks);
230        goto done;
231    }
232
233    /*
234     * OK, time to copy in the data
235     */
236    if (sys_ioctl(in_fd, BLKGETSIZE, (unsigned long)&devblocks) < 0)
237        devblocks = 0;
238    else
239        devblocks >>= 1;
240
241    if (strcmp(from, "/initrd.image") == 0)
242        devblocks = nblocks;
243
244    if (devblocks == 0) {
245        printk(KERN_ERR "RAMDISK: could not determine device size\n");
246        goto done;
247    }
248
249    buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
250    if (!buf) {
251        printk(KERN_ERR "RAMDISK: could not allocate buffer\n");
252        goto done;
253    }
254
255    printk(KERN_NOTICE "RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
256        nblocks, ((nblocks-1)/devblocks)+1, nblocks>devblocks ? "s" : "");
257    for (i = 0, disk = 1; i < nblocks; i++) {
258        if (i && (i % devblocks == 0)) {
259            printk("done disk #%d.\n", disk++);
260            rotate = 0;
261            if (sys_close(in_fd)) {
262                printk("Error closing the disk.\n");
263                goto noclose_input;
264            }
265            change_floppy("disk #%d", disk);
266            in_fd = sys_open(from, O_RDONLY, 0);
267            if (in_fd < 0) {
268                printk("Error opening disk.\n");
269                goto noclose_input;
270            }
271            printk("Loading disk #%d... ", disk);
272        }
273        sys_read(in_fd, buf, BLOCK_SIZE);
274        sys_write(out_fd, buf, BLOCK_SIZE);
275#if !defined(CONFIG_S390)
276        if (!(i % 16)) {
277            printk("%c\b", rotator[rotate & 0x3]);
278            rotate++;
279        }
280#endif
281    }
282    printk("done.\n");
283
284successful_load:
285    res = 1;
286done:
287    sys_close(in_fd);
288noclose_input:
289    sys_close(out_fd);
290out:
291    kfree(buf);
292    sys_unlink("/dev/ram");
293    return res;
294}
295
296int __init rd_load_disk(int n)
297{
298    if (rd_prompt)
299        change_floppy("root floppy disk to be loaded into RAM disk");
300    create_dev("/dev/root", ROOT_DEV);
301    create_dev("/dev/ram", MKDEV(RAMDISK_MAJOR, n));
302    return rd_load_image("/dev/root");
303}
304
305static int exit_code;
306static int decompress_error;
307static int crd_infd, crd_outfd;
308
309static int __init compr_fill(void *buf, unsigned int len)
310{
311    int r = sys_read(crd_infd, buf, len);
312    if (r < 0)
313        printk(KERN_ERR "RAMDISK: error while reading compressed data");
314    else if (r == 0)
315        printk(KERN_ERR "RAMDISK: EOF while reading compressed data");
316    return r;
317}
318
319static int __init compr_flush(void *window, unsigned int outcnt)
320{
321    int written = sys_write(crd_outfd, window, outcnt);
322    if (written != outcnt) {
323        if (decompress_error == 0)
324            printk(KERN_ERR
325                   "RAMDISK: incomplete write (%d != %d)\n",
326                   written, outcnt);
327        decompress_error = 1;
328        return -1;
329    }
330    return outcnt;
331}
332
333static void __init error(char *x)
334{
335    printk(KERN_ERR "%s\n", x);
336    exit_code = 1;
337    decompress_error = 1;
338}
339
340static int __init crd_load(int in_fd, int out_fd, decompress_fn deco)
341{
342    int result;
343    crd_infd = in_fd;
344    crd_outfd = out_fd;
345    result = deco(NULL, 0, compr_fill, compr_flush, NULL, NULL, error);
346    if (decompress_error)
347        result = 1;
348    return result;
349}
350

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