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/*
* Copyright (C) 1999 by Andries Brouwer
* Copyright (C) 1999, 2000, 2003 by Theodore Ts'o
* Copyright (C) 2001 by Andreas Dilger
* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2008 Karel Zak <kzak@redhat.com>
*
* This file may be redistributed under the terms of the
* GNU Lesser General Public License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdint.h>
#include "superblocks.h"
#include "crc32.h"
struct cramfs_super
{
uint8_t magic[4];
uint32_t size;
uint32_t flags;
uint32_t future;
uint8_t signature[16];
struct cramfs_info
{
uint32_t crc;
uint32_t edition;
uint32_t blocks;
uint32_t files;
} __attribute__((packed)) info;
uint8_t name[16];
} __attribute__((packed));
#define CRAMFS_FLAG_FSID_VERSION_2 0x00000001 /* fsid version #2 */
static int cramfs_is_little_endian(const struct blkid_idmag *mag)
{
assert(mag->len == 4);
return memcmp(mag->magic, "\x45\x3d\xcd\x28", 4) == 0;
}
static uint32_t cfs32_to_cpu(int le, uint32_t value)
{
if (le)
return le32_to_cpu(value);
else
return be32_to_cpu(value);
}
static int cramfs_verify_csum(blkid_probe pr, const struct blkid_idmag *mag,
struct cramfs_super *cs, int le)
{
uint32_t crc, expected, csummed_size;
unsigned char *csummed;
expected = cfs32_to_cpu(le, cs->info.crc);
csummed_size = cfs32_to_cpu(le, cs->size);
if (csummed_size > (1 << 16)
|| csummed_size < sizeof(struct cramfs_super))
return 0;
csummed = blkid_probe_get_sb_buffer(pr, mag, csummed_size);
if (!csummed)
return 0;
memset(csummed + offsetof(struct cramfs_super, info.crc), 0, sizeof(uint32_t));
crc = ~ul_crc32(~0LL, csummed, csummed_size);
return blkid_probe_verify_csum(pr, crc, expected);
}
static int probe_cramfs(blkid_probe pr, const struct blkid_idmag *mag)
{
struct cramfs_super *cs;
cs = blkid_probe_get_sb(pr, mag, struct cramfs_super);
if (!cs)
return errno ? -errno : 1;
int le = cramfs_is_little_endian(mag);
int v2 = cfs32_to_cpu(le, cs->flags) & CRAMFS_FLAG_FSID_VERSION_2;
if (v2 && !cramfs_verify_csum(pr, mag, cs, le))
return 1;
blkid_probe_set_label(pr, cs->name, sizeof(cs->name));
blkid_probe_set_fssize(pr, cfs32_to_cpu(le, cs->size));
blkid_probe_sprintf_version(pr, "%d", v2 ? 2 : 1);
blkid_probe_set_fsendianness(pr,
le ? BLKID_ENDIANNESS_LITTLE : BLKID_ENDIANNESS_BIG);
return 0;
}
const struct blkid_idinfo cramfs_idinfo =
{
.name = "cramfs",
.usage = BLKID_USAGE_FILESYSTEM,
.probefunc = probe_cramfs,
.magics =
{
{ .magic = "\x45\x3d\xcd\x28", .len = 4 },
{ .magic = "\x28\xcd\x3d\x45", .len = 4 },
{ NULL }
}
};
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