rw_bitmaps.c revision 1f2da2c01108544b7ee7020bc6e3da1e58f29a3e
1/* 2 * rw_bitmaps.c --- routines to read and write the inode and block bitmaps. 3 * 4 * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o. 5 * 6 * %Begin-Header% 7 * This file may be redistributed under the terms of the GNU Public 8 * License. 9 * %End-Header% 10 */ 11 12#include <stdio.h> 13#include <string.h> 14#if HAVE_UNISTD_H 15#include <unistd.h> 16#endif 17#include <fcntl.h> 18#include <time.h> 19#ifdef HAVE_SYS_STAT_H 20#include <sys/stat.h> 21#endif 22#ifdef HAVE_SYS_TYPES_H 23#include <sys/types.h> 24#endif 25 26#include "ext2_fs.h" 27#include "ext2fs.h" 28#include "e2image.h" 29 30#if defined(__powerpc__) && defined(EXT2FS_ENABLE_SWAPFS) 31/* 32 * On the PowerPC, the big-endian variant of the ext2 filesystem 33 * has its bitmaps stored as 32-bit words with bit 0 as the LSB 34 * of each word. Thus a bitmap with only bit 0 set would be, as 35 * a string of bytes, 00 00 00 01 00 ... 36 * To cope with this, we byte-reverse each word of a bitmap if 37 * we have a big-endian filesystem, that is, if we are *not* 38 * byte-swapping other word-sized numbers. 39 */ 40#define EXT2_BIG_ENDIAN_BITMAPS 41#endif 42 43#ifdef EXT2_BIG_ENDIAN_BITMAPS 44static void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes) 45{ 46 __u32 *p = (__u32 *) bitmap; 47 int n; 48 49 for (n = nbytes / sizeof(__u32); n > 0; --n, ++p) 50 *p = ext2fs_swab32(*p); 51} 52#endif 53 54static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block) 55{ 56 dgrp_t i; 57 unsigned int j; 58 int block_nbytes, inode_nbytes; 59 unsigned int nbits; 60 errcode_t retval; 61 char *block_bitmap, *inode_bitmap; 62 char *block_buf, *inode_buf; 63 blk_t blk; 64 65 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 66 67 if (!(fs->flags & EXT2_FLAG_RW)) 68 return EXT2_ET_RO_FILSYS; 69 inode_nbytes = block_nbytes = 0; 70 block_bitmap = inode_bitmap = 0; 71 if (do_block) { 72 block_bitmap = fs->block_map->bitmap; 73 block_nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8; 74 retval = ext2fs_get_mem(fs->blocksize, &block_buf); 75 if (retval) 76 return retval; 77 memset(block_buf, 0xff, fs->blocksize); 78 } 79 if (do_inode) { 80 inode_bitmap = fs->inode_map->bitmap; 81 inode_nbytes = (size_t) 82 ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8); 83 retval = ext2fs_get_mem(fs->blocksize, &inode_buf); 84 if (retval) 85 return retval; 86 memset(inode_buf, 0xff, fs->blocksize); 87 } 88 89 for (i = 0; i < fs->group_desc_count; i++) { 90 if (!block_bitmap || !do_block) 91 goto skip_block_bitmap; 92 93 memcpy(block_buf, block_bitmap, block_nbytes); 94 if (i == fs->group_desc_count - 1) { 95 /* Force bitmap padding for the last group */ 96 nbits = ((fs->super->s_blocks_count 97 - fs->super->s_first_data_block) 98 % EXT2_BLOCKS_PER_GROUP(fs->super)); 99 if (nbits) 100 for (j = nbits; j < fs->blocksize * 8; j++) 101 ext2fs_set_bit(j, block_buf); 102 } 103 blk = fs->group_desc[i].bg_block_bitmap; 104 if (blk) { 105#ifdef EXT2_BIG_ENDIAN_BITMAPS 106 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) || 107 (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))) 108 ext2fs_swap_bitmap(fs, block_buf, 109 block_nbytes); 110#endif 111 retval = io_channel_write_blk(fs->io, blk, 1, 112 block_buf); 113 if (retval) 114 return EXT2_ET_BLOCK_BITMAP_WRITE; 115 } 116 block_bitmap += block_nbytes; 117 skip_block_bitmap: 118 119 if (!inode_bitmap || !do_inode) 120 continue; 121 122 memcpy(inode_buf, inode_bitmap, inode_nbytes); 123 blk = fs->group_desc[i].bg_inode_bitmap; 124 if (blk) { 125#ifdef EXT2_BIG_ENDIAN_BITMAPS 126 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) || 127 (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))) 128 ext2fs_swap_bitmap(fs, inode_buf, 129 inode_nbytes); 130#endif 131 retval = io_channel_write_blk(fs->io, blk, 1, 132 inode_buf); 133 if (retval) 134 return EXT2_ET_INODE_BITMAP_WRITE; 135 } 136 inode_bitmap += inode_nbytes; 137 138 } 139 if (do_block) { 140 fs->flags &= ~EXT2_FLAG_BB_DIRTY; 141 ext2fs_free_mem(&block_buf); 142 } 143 if (do_inode) { 144 fs->flags &= ~EXT2_FLAG_IB_DIRTY; 145 ext2fs_free_mem(&inode_buf); 146 } 147 return 0; 148} 149 150static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block) 151{ 152 dgrp_t i; 153 char *block_bitmap = 0, *inode_bitmap = 0; 154 char *buf; 155 errcode_t retval; 156 int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8; 157 int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8; 158 blk_t blk; 159 160 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 161 162 fs->write_bitmaps = ext2fs_write_bitmaps; 163 164 retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf); 165 if (retval) 166 return retval; 167 if (do_block) { 168 if (fs->block_map) 169 ext2fs_free_block_bitmap(fs->block_map); 170 sprintf(buf, "block bitmap for %s", fs->device_name); 171 retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map); 172 if (retval) 173 goto cleanup; 174 block_bitmap = fs->block_map->bitmap; 175 } 176 if (do_inode) { 177 if (fs->inode_map) 178 ext2fs_free_inode_bitmap(fs->inode_map); 179 sprintf(buf, "inode bitmap for %s", fs->device_name); 180 retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map); 181 if (retval) 182 goto cleanup; 183 inode_bitmap = fs->inode_map->bitmap; 184 } 185 ext2fs_free_mem(&buf); 186 187 if (fs->flags & EXT2_FLAG_IMAGE_FILE) { 188 if (inode_bitmap) { 189 blk = (fs->image_header->offset_inodemap / 190 fs->blocksize); 191 retval = io_channel_read_blk(fs->image_io, blk, 192 -(inode_nbytes * fs->group_desc_count), 193 inode_bitmap); 194 if (retval) 195 goto cleanup; 196 } 197 if (block_bitmap) { 198 blk = (fs->image_header->offset_blockmap / 199 fs->blocksize); 200 retval = io_channel_read_blk(fs->image_io, blk, 201 -(block_nbytes * fs->group_desc_count), 202 block_bitmap); 203 if (retval) 204 goto cleanup; 205 } 206 return 0; 207 } 208 209 for (i = 0; i < fs->group_desc_count; i++) { 210 if (block_bitmap) { 211 blk = fs->group_desc[i].bg_block_bitmap; 212 if (blk) { 213 retval = io_channel_read_blk(fs->io, blk, 214 -block_nbytes, block_bitmap); 215 if (retval) { 216 retval = EXT2_ET_BLOCK_BITMAP_READ; 217 goto cleanup; 218 } 219#ifdef EXT2_BIG_ENDIAN_BITMAPS 220 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) || 221 (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))) 222 ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes); 223#endif 224 } else 225 memset(block_bitmap, 0, block_nbytes); 226 block_bitmap += block_nbytes; 227 } 228 if (inode_bitmap) { 229 blk = fs->group_desc[i].bg_inode_bitmap; 230 if (blk) { 231 retval = io_channel_read_blk(fs->io, blk, 232 -inode_nbytes, inode_bitmap); 233 if (retval) { 234 retval = EXT2_ET_INODE_BITMAP_READ; 235 goto cleanup; 236 } 237#ifdef EXT2_BIG_ENDIAN_BITMAPS 238 if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) || 239 (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))) 240 ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes); 241#endif 242 } else 243 memset(inode_bitmap, 0, inode_nbytes); 244 inode_bitmap += inode_nbytes; 245 } 246 } 247 return 0; 248 249cleanup: 250 if (do_block) { 251 ext2fs_free_mem(&fs->block_map); 252 fs->block_map = 0; 253 } 254 if (do_inode) { 255 ext2fs_free_mem(&fs->inode_map); 256 fs->inode_map = 0; 257 } 258 if (buf) 259 ext2fs_free_mem(&buf); 260 return retval; 261} 262 263errcode_t ext2fs_read_inode_bitmap(ext2_filsys fs) 264{ 265 return read_bitmaps(fs, 1, 0); 266} 267 268errcode_t ext2fs_read_block_bitmap(ext2_filsys fs) 269{ 270 return read_bitmaps(fs, 0, 1); 271} 272 273errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs) 274{ 275 return write_bitmaps(fs, 1, 0); 276} 277 278errcode_t ext2fs_write_block_bitmap (ext2_filsys fs) 279{ 280 return write_bitmaps(fs, 0, 1); 281} 282 283errcode_t ext2fs_read_bitmaps(ext2_filsys fs) 284{ 285 if (fs->inode_map && fs->block_map) 286 return 0; 287 288 return read_bitmaps(fs, !fs->inode_map, !fs->block_map); 289} 290 291errcode_t ext2fs_write_bitmaps(ext2_filsys fs) 292{ 293 int do_inode = fs->inode_map && ext2fs_test_ib_dirty(fs); 294 int do_block = fs->block_map && ext2fs_test_bb_dirty(fs); 295 296 if (!do_inode && !do_block) 297 return 0; 298 299 return write_bitmaps(fs, do_inode, do_block); 300} 301