Logo Search packages:      
Sourcecode: ldiskfsprogs version File versions  Download package

openfs.c

/*
 * openfs.c --- open an ext2 filesystem
 * 
 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
 * 
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>
#include <time.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#include "ext2_fs.h"


#include "ext2fs.h"
#include "e2image.h"

blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
{
      int   bg;
      int   has_super = 0;
      int   ret_blk;

      if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
          (i < fs->super->s_first_meta_bg))
            return (group_block + i + 1);

      bg = (fs->blocksize / sizeof (struct ext2_group_desc)) * i;
      if (ext2fs_bg_has_super(fs, bg))
            has_super = 1;
      ret_blk = (fs->super->s_first_data_block + has_super + 
               (bg * fs->super->s_blocks_per_group));
      /*
       * If group_block is not the normal value, we're trying to use
       * the backup group descriptors and superblock --- so use the
       * alternate location of the second block group in the
       * metablock group.  Ideally we should be testing each bg
       * descriptor block individually for correctness, but we don't
       * have the infrastructure in place to do that.
       */
      if (group_block != fs->super->s_first_data_block &&
          ((ret_blk + fs->super->s_blocks_per_group) <
           fs->super->s_blocks_count))
            ret_blk += fs->super->s_blocks_per_group;
      return ret_blk;
}

errcode_t ext2fs_open(const char *name, int flags, int superblock,
                  unsigned int block_size, io_manager manager, 
                  ext2_filsys *ret_fs)
{
      return ext2fs_open2(name, 0, flags, superblock, block_size, 
                      manager, ret_fs);
}

/*
 *  Note: if superblock is non-zero, block-size must also be non-zero.
 *    Superblock and block_size can be zero to use the default size.
 *
 * Valid flags for ext2fs_open()
 * 
 *    EXT2_FLAG_RW      - Open the filesystem for read/write.
 *    EXT2_FLAG_FORCE - Open the filesystem even if some of the
 *                      features aren't supported.
 *    EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
 */
errcode_t ext2fs_open2(const char *name, const char *io_options,
                   int flags, int superblock,
                   unsigned int block_size, io_manager manager, 
                   ext2_filsys *ret_fs)
{
      ext2_filsys fs;
      errcode_t   retval;
      unsigned long     i;
      __u32       features;
      int         j, groups_per_block, blocks_per_group, io_flags;
      blk_t       group_block, blk;
      char        *dest, *cp;
      struct ext2_group_desc *gdp;
      
      EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);

      retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
      if (retval)
            return retval;
      
      memset(fs, 0, sizeof(struct struct_ext2_filsys));
      fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
      fs->flags = flags;
      /* don't overwrite sb backups unless flag is explicitly cleared */
      fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
      fs->umask = 022;
      retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
      if (retval)
            goto cleanup;
      strcpy(fs->device_name, name);
      cp = strchr(fs->device_name, '?');
      if (!io_options && cp) {
            *cp++ = 0;
            io_options = cp;
      }
            
      io_flags = 0;
      if (flags & EXT2_FLAG_RW)
            io_flags |= IO_FLAG_RW;
      if (flags & EXT2_FLAG_EXCLUSIVE)
            io_flags |= IO_FLAG_EXCLUSIVE;
      retval = manager->open(fs->device_name, io_flags, &fs->io);
      if (retval)
            goto cleanup;
      if (io_options && 
          (retval = io_channel_set_options(fs->io, io_options)))
            goto cleanup;
      fs->image_io = fs->io;
      fs->io->app_data = fs;
      retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
      if (retval)
            goto cleanup;
      if (flags & EXT2_FLAG_IMAGE_FILE) {
            retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
                              &fs->image_header);
            if (retval)
                  goto cleanup;
            retval = io_channel_read_blk(fs->io, 0,
                                   -(int)sizeof(struct ext2_image_hdr),
                                   fs->image_header);
            if (retval)
                  goto cleanup;
            if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
                  return EXT2_ET_MAGIC_E2IMAGE;
            superblock = 1;
            block_size = fs->image_header->fs_blocksize;
      }

      /*
       * If the user specifies a specific block # for the
       * superblock, then he/she must also specify the block size!
       * Otherwise, read the master superblock located at offset
       * SUPERBLOCK_OFFSET from the start of the partition.
       *
       * Note: we only save a backup copy of the superblock if we
       * are reading the superblock from the primary superblock location.
       */
      if (superblock) {
            if (!block_size) {
                  retval = EXT2_ET_INVALID_ARGUMENT;
                  goto cleanup;
            }
            io_channel_set_blksize(fs->io, block_size);
            group_block = superblock;
            fs->orig_super = 0;
      } else {
            io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
            superblock = 1;
            group_block = 0;
            retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
            if (retval)
                  goto cleanup;
      }
      retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
                             fs->super);
      if (retval)
            goto cleanup;
      if (fs->orig_super)
            memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);

#ifdef EXT2FS_ENABLE_SWAPFS
      if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
          (fs->flags & EXT2_FLAG_SWAP_BYTES)) {
            fs->flags |= EXT2_FLAG_SWAP_BYTES;

            ext2fs_swap_super(fs->super);
      }
#endif
      
      if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
            retval = EXT2_ET_BAD_MAGIC;
            goto cleanup;
      }
      if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
            retval = EXT2_ET_REV_TOO_HIGH;
            goto cleanup;
      }

      /*
       * Check for feature set incompatibility
       */
      if (!(flags & EXT2_FLAG_FORCE)) {
            features = fs->super->s_feature_incompat;
#ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
            if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
                  features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
#endif
            if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
                  retval = EXT2_ET_UNSUPP_FEATURE;
                  goto cleanup;
            }

            features = fs->super->s_feature_ro_compat;
#ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
            if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
                  features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
#endif
            if ((flags & EXT2_FLAG_RW) &&
                (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
                  retval = EXT2_ET_RO_UNSUPP_FEATURE;
                  goto cleanup;
            }

            if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
                (fs->super->s_feature_incompat &
                 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
                  retval = EXT2_ET_UNSUPP_FEATURE;
                  goto cleanup;
            }
      }
      
      fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
      if (fs->blocksize == 0) {
            retval = EXT2_ET_CORRUPT_SUPERBLOCK;
            goto cleanup;
      }
      if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
            retval = EXT2_ET_CORRUPT_SUPERBLOCK;
            goto cleanup;
      }
      fs->fragsize = EXT2_FRAG_SIZE(fs->super);
      fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
                               EXT2_INODE_SIZE(fs->super) +
                               EXT2_BLOCK_SIZE(fs->super) - 1) /
                              EXT2_BLOCK_SIZE(fs->super));
      if (block_size) {
            if (block_size != fs->blocksize) {
                  retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
                  goto cleanup;
            }
      }
      /*
       * Set the blocksize to the filesystem's blocksize.
       */
      io_channel_set_blksize(fs->io, fs->blocksize);

      /*
       * If this is an external journal device, don't try to read
       * the group descriptors, because they're not there.
       */
      if (fs->super->s_feature_incompat &
          EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
            fs->group_desc_count = 0;
            *ret_fs = fs;
            return 0;
      }
      
      /*
       * Read group descriptors
       */
      blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
      if (blocks_per_group == 0 ||
          blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
          fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
            retval = EXT2_ET_CORRUPT_SUPERBLOCK;
            goto cleanup;
      }
      fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
                                     fs->super->s_first_data_block,
                                     blocks_per_group);
      fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
                                EXT2_DESC_PER_BLOCK(fs->super));
      retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
                        &fs->group_desc);
      if (retval)
            goto cleanup;
      if (!group_block)
            group_block = fs->super->s_first_data_block;
      dest = (char *) fs->group_desc;
      groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc);
      for (i=0 ; i < fs->desc_blocks; i++) {
            blk = ext2fs_descriptor_block_loc(fs, group_block, i);
            retval = io_channel_read_blk(fs->io, blk, 1, dest);
            if (retval)
                  goto cleanup;
#ifdef EXT2FS_ENABLE_SWAPFS
            if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
                  gdp = (struct ext2_group_desc *) dest;
                  for (j=0; j < groups_per_block; j++)
                        ext2fs_swap_group_desc(gdp++);
            }
#endif
            dest += fs->blocksize;
      }

      fs->stride = fs->super->s_raid_stride;

      fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
      *ret_fs = fs;
      return 0;
cleanup:
      if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
            *ret_fs = fs;
      else
            ext2fs_free(fs);
      return retval;
}

/*
 * Set/get the filesystem data I/O channel.
 * 
 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 */
errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
{
      if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
            return EXT2_ET_NOT_IMAGE_FILE;
      if (old_io) {
            *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
      }
      return 0;
}

errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
{
      if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
            return EXT2_ET_NOT_IMAGE_FILE;
      fs->io = new_io ? new_io : fs->image_io;
      return 0;
}

errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
{
      if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
            return EXT2_ET_NOT_IMAGE_FILE;
      fs->io = fs->image_io = new_io;
      fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW | 
            EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
      fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
      return 0;
}

Generated by  Doxygen 1.6.0   Back to index