cramfsck.c

制作cramfs文件系统的工具

/*
 * cramfsck - check a cramfs file system
 *
 * Copyright (C) 2000-2002 Transmeta Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * 1999/12/03: Linus Torvalds (cramfs tester and unarchive program)
 * 2000/06/03: Daniel Quinlan (CRC and length checking program)
 * 2000/06/04: Daniel Quinlan (merged programs, added options, support
 *                            for special files, preserve permissions and
 *                            ownership, cramfs superblock v2, bogus mode
 *                            test, pathname length test, etc.)
 * 2000/06/06: Daniel Quinlan (support for holes, pretty-printing,
 *                            symlink size test)
 * 2000/07/11: Daniel Quinlan (file length tests, start at offset 0 or 512,
 *                            fsck-compatible exit codes)
 * 2000/07/15: Daniel Quinlan (initial support for block devices)
 * 2002/01/10: Daniel Quinlan (additional checks, test more return codes,
 *                            use read if mmap fails, standardize messages)
 */

/* compile-time options */
#define INCLUDE_FS_TESTS	/* include cramfs checking and extraction */

#define _GNU_SOURCE
#include <sys/types.h>
#include <stdio.h>
#include <stdarg.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <dirent.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/sysmacros.h>
#include <utime.h>
#include <sys/ioctl.h>
#define _LINUX_STRING_H_
#include <linux/fs.h>
#include <linux/cramfs_fs.h>
#include <zlib.h>

/* Exit codes used by fsck-type programs */
#define FSCK_OK          0	/* No errors */
#define FSCK_NONDESTRUCT 1	/* File system errors corrected */
#define FSCK_REBOOT      2	/* System should be rebooted */
#define FSCK_UNCORRECTED 4	/* File system errors left uncorrected */
#define FSCK_ERROR       8	/* Operational error */
#define FSCK_USAGE       16	/* Usage or syntax error */
#define FSCK_LIBRARY     128	/* Shared library error */

#define PAD_SIZE 512
#define PAGE_CACHE_SIZE (4096)

static const char *progname = "cramfsck";

static int fd;			/* ROM image file descriptor */
static char *filename;		/* ROM image filename */
struct cramfs_super super;	/* just find the cramfs superblock once */
static int opt_verbose = 0;	/* 1 = verbose (-v), 2+ = very verbose (-vv) */
#ifdef INCLUDE_FS_TESTS
static int opt_extract = 0;		/* extract cramfs (-x) */
static char *extract_dir = "root";	/* extraction directory (-x) */
static uid_t euid;			/* effective UID */

/* (cramfs_super + start) <= start_dir < end_dir <= start_data <= end_data */
static unsigned long start_dir = ~0UL;	/* start of first non-root inode */
static unsigned long end_dir = 0;	/* end of the directory structure */
static unsigned long start_data = ~0UL;	/* start of the data (256 MB = max) */
static unsigned long end_data = 0;	/* end of the data */

/* Guarantee access to at least 8kB at a time */
#define ROMBUFFER_BITS	13
#define ROMBUFFERSIZE	(1 << ROMBUFFER_BITS)
#define ROMBUFFERMASK	(ROMBUFFERSIZE-1)
static char read_buffer[ROMBUFFERSIZE * 2];
static unsigned long read_buffer_block = ~0UL;

/* Uncompressing data structures... */
static char outbuffer[PAGE_CACHE_SIZE*2];
static z_stream stream;

/* Prototypes */
static void expand_fs(char *, struct cramfs_inode *);
#endif /* INCLUDE_FS_TESTS */

/* Input status of 0 to print help and exit without an error. */
static void usage(int status)
{
	FILE *stream = status ? stderr : stdout;

	fprintf(stream, "usage: %s [-hv] [-x dir] file\n"
		" -h         print this help\n"
		" -x dir     extract into dir\n"
		" -v         be more verbose\n"
		" file       file to test\n", progname);

	exit(status);
}

static void die(int status, int syserr, const char *fmt, ...)
{
	va_list arg_ptr;
	int save = errno;

	fflush(0);
	va_start(arg_ptr, fmt);
	fprintf(stderr, "%s: ", progname);
	vfprintf(stderr, fmt, arg_ptr);
	if (syserr) {
		fprintf(stderr, ": %s", strerror(save));
	}
	fprintf(stderr, "\n");
	va_end(arg_ptr);
	exit(status);
}

static void test_super(int *start, size_t *length) {
	struct stat st;

	/* find the physical size of the file or block device */
	if (stat(filename, &st) < 0) {
		die(FSCK_ERROR, 1, "stat failed: %s", filename);
	}
	fd = open(filename, O_RDONLY);
	if (fd < 0) {
		die(FSCK_ERROR, 1, "open failed: %s", filename);
	}
	if (S_ISBLK(st.st_mode)) {
		if (ioctl(fd, BLKGETSIZE, length) < 0) {
			die(FSCK_ERROR, 1, "ioctl failed: unable to determine device size: %s", filename);
		}
		*length = *length * 512;
	}
	else if (S_ISREG(st.st_mode)) {
		*length = st.st_size;
	}
	else {
		die(FSCK_ERROR, 0, "not a block device or file: %s", filename);
	}

	if (*length < sizeof(struct cramfs_super)) {
		die(FSCK_UNCORRECTED, 0, "file length too short");
	}

	/* find superblock */
	if (read(fd, &super, sizeof(super)) != sizeof(super)) {
		die(FSCK_ERROR, 1, "read failed: %s", filename);
	}
	if (super.magic == CRAMFS_MAGIC) {
		*start = 0;
	}
	else if (*length >= (PAD_SIZE + sizeof(super))) {
		lseek(fd, PAD_SIZE, SEEK_SET);
		if (read(fd, &super, sizeof(super)) != sizeof(super)) {
			die(FSCK_ERROR, 1, "read failed: %s", filename);
		}
		if (super.magic == CRAMFS_MAGIC) {
			*start = PAD_SIZE;
		}
	}

	/* superblock tests */
	if (super.magic != CRAMFS_MAGIC) {
		die(FSCK_UNCORRECTED, 0, "superblock magic not found");
	}
	if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
		die(FSCK_ERROR, 0, "unsupported filesystem features");
	}
	if (super.size < PAGE_CACHE_SIZE) {
		die(FSCK_UNCORRECTED, 0, "superblock size (%d) too small", super.size);
	}
	if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
		if (super.fsid.files == 0) {
			die(FSCK_UNCORRECTED, 0, "zero file count");
		}
		if (*length < super.size) {
			die(FSCK_UNCORRECTED, 0, "file length too short");
		}
		else if (*length > super.size) {
			fprintf(stderr, "warning: file extends past end of filesystem\n");
		}
	}
	else {
		fprintf(stderr, "warning: old cramfs format\n");
	}
}

static void test_crc(int start)
{
	void *buf;
	u32 crc;

	if (!(super.flags & CRAMFS_FLAG_FSID_VERSION_2)) {
#ifdef INCLUDE_FS_TESTS
		return;
#else /* not INCLUDE_FS_TESTS */
		die(FSCK_USAGE, 0, "unable to test CRC: old cramfs format");
#endif /* not INCLUDE_FS_TESTS */
	}

	crc = crc32(0L, Z_NULL, 0);

	buf = mmap(NULL, super.size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
	if (buf == MAP_FAILED) {
		buf = mmap(NULL, super.size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
		if (buf != MAP_FAILED) {
			lseek(fd, 0, SEEK_SET);
			read(fd, buf, super.size);
		}
	}
	if (buf != MAP_FAILED) {
		((struct cramfs_super *) (buf+start))->fsid.crc = crc32(0L, Z_NULL, 0);
		crc = crc32(crc, buf+start, super.size-start);
		munmap(buf, super.size);
	}
	else {
		int retval;
		size_t length = 0;

		buf = malloc(4096);
		if (!buf) {
			die(FSCK_ERROR, 1, "malloc failed");
		}
		lseek(fd, start, SEEK_SET);
		for (;;) {
			retval = read(fd, buf, 4096);
			if (retval < 0) {
				die(FSCK_ERROR, 1, "read failed: %s", filename);
			}
			else if (retval == 0) {
				break;
			}
			if (length == 0) {
				((struct cramfs_super *) buf)->fsid.crc = crc32(0L, Z_NULL, 0);
			}
			length += retval;
			if (length > (super.size-start)) {
				crc = crc32(crc, buf, retval - (length - (super.size-start)));
				break;
			}
			crc = crc32(crc, buf, retval);
		}
		free(buf);
	}

	if (crc != super.fsid.crc) {
		die(FSCK_UNCORRECTED, 0, "crc error");
	}
}

#ifdef INCLUDE_FS_TESTS
static void print_node(char type, struct cramfs_inode *i, char *name)
{
	char info[10];

	if (S_ISCHR(i->mode) || (S_ISBLK(i->mode))) {
		/* major/minor numbers can be as high as 2^12 or 4096 */
		snprintf(info, 10, "%4d,%4d", major(i->size), minor(i->size));
	}
	else {
		/* size be as high as 2^24 or 16777216 */
		snprintf(info, 10, "%9d", i->size);
	}

	printf("%c %04o %s %5d:%-3d %s\n",
	       type, i->mode & ~S_IFMT, info, i->uid, i->gid, name);
}

/*
 * Create a fake "blocked" access
 */
static void *romfs_read(unsigned long offset)
{
	unsigned int block = offset >> ROMBUFFER_BITS;
	if (block != read_buffer_block) {
		read_buffer_block = block;
		lseek(fd, block << ROMBUFFER_BITS, SEEK_SET);
		read(fd, read_buffer, ROMBUFFERSIZE * 2);
	}
	return read_buffer + (offset & ROMBUFFERMASK);
}

static struct cramfs_inode *cramfs_iget(struct cramfs_inode * i)
{
	struct cramfs_inode *inode = malloc(sizeof(struct cramfs_inode));

	if (!inode) {
		die(FSCK_ERROR, 1, "malloc failed");
	}
	*inode = *i;
	return inode;
}

static struct cramfs_inode *iget(unsigned int ino)
{
	return cramfs_iget(romfs_read(ino));
}

static void iput(struct cramfs_inode *inode)
{
	free(inode);
}

/*
 * Return the offset of the root directory
 */
static struct cramfs_inode *read_super(void)
{
	unsigned long offset = super.root.offset << 2;

	if (!S_ISDIR(super.root.mode))
		die(FSCK_UNCORRECTED, 0, "root inode is not directory");
	if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
	    ((offset != sizeof(struct cramfs_super)) &&
	     (offset != PAD_SIZE + sizeof(struct cramfs_super))))
	{
		die(FSCK_UNCORRECTED, 0, "bad root offset (%lu)", offset);
	}
	return cramfs_iget(&super.root);
}

static int uncompress_block(void *src, int len)
{
	int err;

	stream.next_in = src;
	stream.avail_in = len;

	stream.next_out = (unsigned char *) outbuffer;
	stream.avail_out = PAGE_CACHE_SIZE*2;

	inflateReset(&stream);

	if (len > PAGE_CACHE_SIZE*2) {
		die(FSCK_UNCORRECTED, 0, "data block too large");
	}
	err = inflate(&stream, Z_FINISH);
	if (err != Z_STREAM_END) {