readfs.c

操作系统源代码

/* readfs - read a MINIX file system	Author: Paul Polderman */

/* Command: readfs - read and extract a MINIX filesystem.
 *
 * Syntax:  readfs [-li] block-special [directory]
 *
 * Flags: -l:	Extract files and dirs and produce a mkfs-listing on stdout
 * 	  -i:	Information only: give the listing, but do not extract files.
 *	  -d:	Don't extract regular files, just the skeleton please.
 *
 * Examples: readfs /dev/fd1		# extract all files from /dev/fd1.
 * 	     readfs -i /dev/hd2		# see what's on /dev/hd2.
 * 	     readfs -l /dev/at0 rootfs	# extract and list the filesystem
 * 					# of /dev/at0 and put the tree
 * 					# in the directory `rootfs'.
 *
 *   Readfs reads a MINIX filesystem and extracts recursively all directories
 * and files, and (optionally) produces a mkfs-listing of them on stdout.
 * The root directory contents are placed in the current directory, unless
 * a directory is given as argument, in which case the contents are put there.
 * Readfs tries to restore the attributes (mode/uid/gid/time) of the files
 * extracted to those of the original files.
 * Special files are created as ordinary files, but the mkfs-listing
 * enables mkfs to restore them to original.
 */

#include <sys/types.h>
#include <sys/dir.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <limits.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <utime.h>

#include <minix/config.h>
#include <minix/const.h>
#include <minix/type.h>
#include "../../fs/const.h"
#include "../../fs/type.h"
#include "../../fs/buf.h"
#include "../../fs/super.h"

#undef printf			/* Definition used only in the kernel */
#include <stdio.h>

/* Compile with -I/user0/ast/minix
 * (i.e. the directory containing the MINIX system sources)
 *
 *	Author: Paul Polderman ([e-mail]) April 1987
 */

char verbose = 0;		/* give a mkfs-listing of the filesystem */
 /* And extracts its contents. */
char noaction = 0;		/* just give a mkfs-listing, do not extract
			 * files. */
char nofiles = 0;		/* only extract the skeleton FS structure */

struct super_block sb;
char pathname[1024];
int inodes_per_block;

_PROTOTYPE(int main, (int argc, char **argv));
_PROTOTYPE(void get_flags, (char *flags));
_PROTOTYPE(void readfs, (char *special_file, char *directory));
_PROTOTYPE(int get_inode, (int fd, Ino_t inum, d1_inode * ip));
_PROTOTYPE(void dump_dir, (int special, d1_inode * ip, char *directory));
_PROTOTYPE(int dump_file, (int special, d1_inode * ip, char *filename));
_PROTOTYPE(int get_fileblock, (int special, d1_inode * ip, block_t b, struct buf * bp));
_PROTOTYPE(int get_block, (int fd, block_t block, struct buf * bp, int type));
_PROTOTYPE(int get_rawblock, (int special, block_t blockno, char *bufp));
_PROTOTYPE(void restore, (char *name, d1_inode * ip));
_PROTOTYPE(void show_info, (char *name, d1_inode * ip, char *path));
_PROTOTYPE(void do_indent, (int i));
_PROTOTYPE(int Mkdir, (char *directory));

int main(argc, argv)
int argc;
char **argv;
{
  switch (argc) {
      case 2:
	pathname[0] = '\0';
	readfs(argv[1], pathname);
	break;
      case 3:
	if (argv[1][0] == '-') {
		get_flags(&argv[1][1]);
		pathname[0] = '\0';
		readfs(argv[2], pathname);
	} else {
		strcpy(pathname, argv[2]);
		readfs(argv[1], pathname);
	}
	break;
      case 4:
	if (argv[1][0] == '-') {
		get_flags(&argv[1][1]);
		strcpy(pathname, argv[3]);
		readfs(argv[2], pathname);
		break;
	}			/* else fall through .. */
      default:
	fprintf(stderr, "Usage: %s [-li] <special> [dirname]\n", argv[0]);
	exit(1);
  }
  return(0);
}

void get_flags(flags)
register char *flags;
{
  while (*flags) {
	switch (*flags) {
	    case 'L':
	    case 'l':	verbose = 1;	break;
	    case 'I':
	    case 'i':
		noaction = 1;
		verbose = 1;
		break;
	    case 'D':
	    case 'd':	nofiles = 1;	break;
	    default:
		fprintf(stderr, "Bad flag: %c\n", *flags);
		break;
	}
	flags++;
  }
}

#define	zone_shift	(sb.s_log_zone_size)	/* zone to block ratio */

void readfs(special_file, directory)
char *special_file, *directory;
/* Readfs: opens the given special file (with MINIX filesystem),
 * and extracts its contents into the given directory.
 */
{
  d1_inode root_inode;
  int special, magic;
  off_t super_b;

  umask(0);

  /* Open the special file */
  if ((special = open(special_file, O_RDONLY)) < 0) {
	fprintf(stderr, "cannot open %s\n", special_file);
	return;
  }

  /* Read the superblock */
  super_b = (off_t) SUPER_BLOCK *(off_t) BLOCK_SIZE;
  if (lseek(special, super_b, SEEK_SET) != super_b) {
	fprintf(stderr, "cannot seek to superblock\n");
	return;
  }
  if (read(special, (char *) &sb, sizeof(struct super_block))
      != sizeof(struct super_block)) {
	fprintf(stderr, "cannot read superblock\n");
	return;
  }

  /* The number of inodes in a block differs in V1 and V2. */
  magic = sb.s_magic;
  if (magic == SUPER_MAGIC || magic == SUPER_REV) {
	inodes_per_block = V1_INODES_PER_BLOCK;
  } else {
	inodes_per_block = V2_INODES_PER_BLOCK;
  }

  /* Is it really a MINIX filesystem ? */
  if (magic != SUPER_MAGIC && magic != SUPER_V2) {
	fprintf(stderr, "%s is not a valid MINIX filesystem\n", special_file);
	return;
  }

  /* Fetch the inode of the root directory */
  if (get_inode(special, (ino_t) ROOT_INODE, &root_inode) < 0) {
	fprintf(stderr, "cannot get inode of root directory\n");
	return;
  }

  /* Print number of blocks and inodes */
  if (verbose) printf("boot\n%ld %d\n",
	       (block_t) sb.s_nzones << zone_shift, sb.s_ninodes);

  /* Extract (recursively) the root directory */
  dump_dir(special, &root_inode, directory);
}

/* Different type of blocks:	(used in routine get_block for caching) */

#define	B_INODE		0	/* Cache #0 is the inode cache */
#define	B_INDIRECT	1	/* Cache #1 is the (dbl) indirect block cache */
#define	B_DATA		2	/* No cache for data blocks (only read once) */

int get_inode(fd, inum, ip)
int fd;
ino_t inum;
d1_inode *ip;

/* Get inode `inum' from the MINIX filesystem. (Uses the inode-cache) */
{
  struct buf bp;
  block_t block;
  block_t ino_block;
  unsigned short ino_offset;

  /* Calculate start of i-list */
  block = SUPER_BLOCK + 1 + sb.s_imap_blocks + sb.s_zmap_blocks;

  /* Calculate block with inode inum */
  ino_block = ((inum - 1) / inodes_per_block);
  ino_offset = ((inum - 1) % inodes_per_block);
  block += ino_block;

  /* Fetch the block */
  if (get_block(fd, block, &bp, B_INODE) == 0) {
	memcpy((void *) ip, (void *) &bp.b_v1_ino[ino_offset], sizeof(d1_inode));
	return(0);
  }

  /* Oeps, foutje .. */
  fprintf(stderr, "cannot find inode %d\n", inum);
  return(-1);
}

static int indent = 0;		/* current indent (used for mkfs-listing) */

void dump_dir(special, ip, directory)
int special;
d1_inode *ip;
char *directory;
/* Make the given directory (if non-NULL),
 * and recursively extract its contents.
 */
{
  register struct direct *dp;
  register int n_entries;
  register char *name;
  block_t b = 0;
  d1_inode dip;
  struct buf bp;

  if (verbose) {
	show_info(directory, ip, "");
	indent++;
  }
  if (!noaction && *directory) {
	/* Try to make the directory if not already there */
	if (Mkdir(directory) != 0 || chdir(directory) < 0) {
		fprintf(stderr, "Mkdir %s failed\n", directory);
		return;
	}
  }
  for (name = directory; *name; name++)	/* Find end of pathname */
	;
  *name++ = '/';		/* Add trailing slash */

  n_entries = (int) (ip->d1_size / (off_t) sizeof(struct direct));
  while (n_entries > 0) {

	/* Read next block of the directory */
	if (get_fileblock(special, ip, b, &bp) < 0) return;
	dp = &bp.b_dir[0];
	if (b++ == (block_t) 0) {
		dp += 2;	/* Skip "." and ".." */
		n_entries -= 2;
	}

	/* Extract the files/directories listed in the block */
	while (n_entries-- > 0 && dp < &bp.b_dir[NR_DIR_ENTRIES]) {
		if (dp->d_ino != (ino_t) 0) {
			if (get_inode(special, dp->d_ino, &dip) < 0) {
				/* Bad luck */
				dp++;
				continue;
			}

			/* Add new pathname-component to `pathname'. */
			strncpy(name, dp->d_name, (size_t) NAME_MAX);
			name[NAME_MAX] = '\0';

			/* Call the right routine */
			if ((dip.d1_mode & I_TYPE) == I_DIRECTORY)
				dump_dir(special, &dip, name);
			else
				dump_file(special, &dip, name);
		}
		dp++;		/* Next entry, please. */
	}
  }
  *--name = '\0';		/* Restore `pathname' to what it was. */
  if (!noaction && *directory) {
	chdir("..");		/* Go back up. */
	restore(directory, ip);	/* Restore mode/owner/accesstime */
  }