Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 | /* * linux/fs/hfs/mdb.c * * Copyright (C) 1995-1997 Paul H. Hargrove * This file may be distributed under the terms of the GNU Public License. * * This file contains functions for reading/writing the MDB. * * "XXX" in a comment is a note to myself to consider changing something. * * In function preconditions the term "valid" applied to a pointer to * a structure means that the pointer is non-NULL and the structure it * points to has all fields initialized to consistent values. * * The code in this file initializes some structures which contain * pointers by calling memset(&foo, 0, sizeof(foo)). * This produces the desired behavior only due to the non-ANSI * assumption that the machine representation of NULL is all zeros. */ #include "hfs.h" /*================ File-local data types ================*/ /* * The HFS Master Directory Block (MDB). * * Also known as the Volume Information Block (VIB), this structure is * the HFS equivalent of a superblock. * * Reference: _Inside Macintosh: Files_ pages 2-59 through 2-62 * * modified for HFS Extended */ struct raw_mdb { hfs_word_t drSigWord; /* Signature word indicating fs type */ hfs_lword_t drCrDate; /* fs creation date/time */ hfs_lword_t drLsMod; /* fs modification date/time */ hfs_word_t drAtrb; /* fs attributes */ hfs_word_t drNmFls; /* number of files in root directory */ hfs_word_t drVBMSt; /* location (in 512-byte blocks) of the volume bitmap */ hfs_word_t drAllocPtr; /* location (in allocation blocks) to begin next allocation search */ hfs_word_t drNmAlBlks; /* number of allocation blocks */ hfs_lword_t drAlBlkSiz; /* bytes in an allocation block */ hfs_lword_t drClpSiz; /* clumpsize, the number of bytes to allocate when extending a file */ hfs_word_t drAlBlSt; /* location (in 512-byte blocks) of the first allocation block */ hfs_lword_t drNxtCNID; /* CNID to assign to the next file or directory created */ hfs_word_t drFreeBks; /* number of free allocation blocks */ hfs_byte_t drVN[28]; /* the volume label */ hfs_lword_t drVolBkUp; /* fs backup date/time */ hfs_word_t drVSeqNum; /* backup sequence number */ hfs_lword_t drWrCnt; /* fs write count */ hfs_lword_t drXTClpSiz; /* clumpsize for the extents B-tree */ hfs_lword_t drCTClpSiz; /* clumpsize for the catalog B-tree */ hfs_word_t drNmRtDirs; /* number of directories in the root directory */ hfs_lword_t drFilCnt; /* number of files in the fs */ hfs_lword_t drDirCnt; /* number of directories in the fs */ hfs_byte_t drFndrInfo[32]; /* data used by the Finder */ hfs_word_t drEmbedSigWord; /* embedded volume signature */ hfs_lword_t drEmbedExtent; /* starting block number (xdrStABN) and number of allocation blocks (xdrNumABlks) occupied by embedded volume */ hfs_lword_t drXTFlSize; /* bytes in the extents B-tree */ hfs_byte_t drXTExtRec[12]; /* extents B-tree's first 3 extents */ hfs_lword_t drCTFlSize; /* bytes in the catalog B-tree */ hfs_byte_t drCTExtRec[12]; /* catalog B-tree's first 3 extents */ }; /*================ Global functions ================*/ /* * hfs_mdb_get() * * Build the in-core MDB for a filesystem, including * the B-trees and the volume bitmap. */ struct hfs_mdb *hfs_mdb_get(hfs_sysmdb sys_mdb, int readonly, hfs_s32 part_start) { struct hfs_mdb *mdb; hfs_buffer buf; struct raw_mdb *raw; unsigned int bs, block; int lcv, limit; hfs_buffer *bmbuf; if (!HFS_NEW(mdb)) { hfs_warn("hfs_fs: out of memory\n"); return NULL; } memset(mdb, 0, sizeof(*mdb)); mdb->magic = HFS_MDB_MAGIC; mdb->sys_mdb = sys_mdb; INIT_LIST_HEAD(&mdb->entry_dirty); hfs_init_waitqueue(&mdb->rename_wait); hfs_init_waitqueue(&mdb->bitmap_wait); /* See if this is an HFS filesystem */ buf = hfs_buffer_get(sys_mdb, part_start + HFS_MDB_BLK, 1); if (!hfs_buffer_ok(buf)) { hfs_warn("hfs_fs: Unable to read superblock\n"); HFS_DELETE(mdb); goto bail2; } raw = (struct raw_mdb *)hfs_buffer_data(buf); if (hfs_get_ns(raw->drSigWord) != htons(HFS_SUPER_MAGIC)) { hfs_buffer_put(buf); HFS_DELETE(mdb); goto bail2; } mdb->buf = buf; bs = hfs_get_hl(raw->drAlBlkSiz); if (!bs || (bs & (HFS_SECTOR_SIZE-1))) { hfs_warn("hfs_fs: bad allocation block size %d != 512\n", bs); hfs_buffer_put(buf); HFS_DELETE(mdb); goto bail2; } mdb->alloc_blksz = bs >> HFS_SECTOR_SIZE_BITS; /* These parameters are read from the MDB, and never written */ mdb->create_date = hfs_get_hl(raw->drCrDate); mdb->fs_ablocks = hfs_get_hs(raw->drNmAlBlks); mdb->fs_start = hfs_get_hs(raw->drAlBlSt) + part_start; mdb->backup_date = hfs_get_hl(raw->drVolBkUp); mdb->clumpablks = (hfs_get_hl(raw->drClpSiz) / mdb->alloc_blksz) >> HFS_SECTOR_SIZE_BITS; memcpy(mdb->vname, raw->drVN, sizeof(raw->drVN)); /* These parameters are read from and written to the MDB */ mdb->modify_date = hfs_get_nl(raw->drLsMod); mdb->attrib = hfs_get_ns(raw->drAtrb); mdb->free_ablocks = hfs_get_hs(raw->drFreeBks); mdb->next_id = hfs_get_hl(raw->drNxtCNID); mdb->write_count = hfs_get_hl(raw->drWrCnt); mdb->root_files = hfs_get_hs(raw->drNmFls); mdb->root_dirs = hfs_get_hs(raw->drNmRtDirs); mdb->file_count = hfs_get_hl(raw->drFilCnt); mdb->dir_count = hfs_get_hl(raw->drDirCnt); /* TRY to get the alternate (backup) MDB. */ lcv = mdb->fs_start + mdb->fs_ablocks * mdb->alloc_blksz; limit = lcv + mdb->alloc_blksz; for (; lcv < limit; ++lcv) { buf = hfs_buffer_get(sys_mdb, lcv, 1); if (hfs_buffer_ok(buf)) { struct raw_mdb *tmp = (struct raw_mdb *)hfs_buffer_data(buf); if (hfs_get_ns(tmp->drSigWord) == htons(HFS_SUPER_MAGIC)) { mdb->alt_buf = buf; break; } } hfs_buffer_put(buf); } if (mdb->alt_buf == NULL) { hfs_warn("hfs_fs: unable to locate alternate MDB\n"); hfs_warn("hfs_fs: continuing without an alternate MDB\n"); } /* read in the bitmap */ block = hfs_get_hs(raw->drVBMSt) + part_start; bmbuf = mdb->bitmap; lcv = (mdb->fs_ablocks + 4095) / 4096; for ( ; lcv; --lcv, ++bmbuf, ++block) { if (!hfs_buffer_ok(*bmbuf = hfs_buffer_get(sys_mdb, block, 1))) { hfs_warn("hfs_fs: unable to read volume bitmap\n"); goto bail1; } } if (!(mdb->ext_tree = hfs_btree_init(mdb, htonl(HFS_EXT_CNID), raw->drXTExtRec, hfs_get_hl(raw->drXTFlSize), hfs_get_hl(raw->drXTClpSiz))) || !(mdb->cat_tree = hfs_btree_init(mdb, htonl(HFS_CAT_CNID), raw->drCTExtRec, hfs_get_hl(raw->drCTFlSize), hfs_get_hl(raw->drCTClpSiz)))) { hfs_warn("hfs_fs: unable to initialize data structures\n"); goto bail1; } if (!(mdb->attrib & htons(HFS_SB_ATTRIB_CLEAN))) { hfs_warn("hfs_fs: WARNING: mounting unclean filesystem.\n"); } else if (!readonly) { /* Mark the volume uncleanly unmounted in case we crash */ hfs_put_ns(mdb->attrib & htons(~HFS_SB_ATTRIB_CLEAN), raw->drAtrb); hfs_buffer_dirty(mdb->buf); hfs_buffer_sync(mdb->buf); } return mdb; bail1: hfs_mdb_put(mdb, readonly); bail2: return NULL; } /* * hfs_mdb_commit() * * Description: * This updates the MDB on disk (look also at hfs_write_super()). * It does not check, if the superblock has been modified, or * if the filesystem has been mounted read-only. It is mainly * called by hfs_write_super() and hfs_btree_extend(). * Input Variable(s): * struct hfs_mdb *mdb: Pointer to the hfs MDB * int backup; * Output Variable(s): * NONE * Returns: * void * Preconditions: * 'mdb' points to a "valid" (struct hfs_mdb). * Postconditions: * The HFS MDB and on disk will be updated, by copying the possibly * modified fields from the in memory MDB (in native byte order) to * the disk block buffer. * If 'backup' is non-zero then the alternate MDB is also written * and the function doesn't return until it is actually on disk. */ void hfs_mdb_commit(struct hfs_mdb *mdb, int backup) { struct raw_mdb *raw = (struct raw_mdb *)hfs_buffer_data(mdb->buf); /* Commit catalog entries to buffers */ hfs_cat_commit(mdb); /* Commit B-tree data to buffers */ hfs_btree_commit(mdb->cat_tree, raw->drCTExtRec, raw->drCTFlSize); hfs_btree_commit(mdb->ext_tree, raw->drXTExtRec, raw->drXTFlSize); /* Update write_count and modify_date */ ++mdb->write_count; mdb->modify_date = hfs_time(); /* These parameters may have been modified, so write them back */ hfs_put_nl(mdb->modify_date, raw->drLsMod); hfs_put_hs(mdb->free_ablocks, raw->drFreeBks); hfs_put_hl(mdb->next_id, raw->drNxtCNID); hfs_put_hl(mdb->write_count, raw->drWrCnt); hfs_put_hs(mdb->root_files, raw->drNmFls); hfs_put_hs(mdb->root_dirs, raw->drNmRtDirs); hfs_put_hl(mdb->file_count, raw->drFilCnt); hfs_put_hl(mdb->dir_count, raw->drDirCnt); /* write MDB to disk */ hfs_buffer_dirty(mdb->buf); /* write the backup MDB, not returning until it is written. * we only do this when either the catalog or extents overflow * files grow. */ if (backup && hfs_buffer_ok(mdb->alt_buf)) { struct raw_mdb *tmp = (struct raw_mdb *) hfs_buffer_data(mdb->alt_buf); if ((hfs_get_hl(tmp->drCTFlSize) < hfs_get_hl(raw->drCTFlSize)) || (hfs_get_hl(tmp->drXTFlSize) < hfs_get_hl(raw->drXTFlSize))) { memcpy(hfs_buffer_data(mdb->alt_buf), hfs_buffer_data(mdb->buf), HFS_SECTOR_SIZE); hfs_buffer_dirty(mdb->alt_buf); hfs_buffer_sync(mdb->alt_buf); } } } /* * hfs_mdb_put() * * Release the resources associated with the in-core MDB. */ void hfs_mdb_put(struct hfs_mdb *mdb, int readonly) { int lcv; /* invalidate cached catalog entries */ hfs_cat_invalidate(mdb); /* free the B-trees */ hfs_btree_free(mdb->ext_tree); hfs_btree_free(mdb->cat_tree); /* free the volume bitmap */ for (lcv = 0; lcv < HFS_BM_MAXBLOCKS; ++lcv) { hfs_buffer_put(mdb->bitmap[lcv]); } /* update volume attributes */ if (!readonly) { struct raw_mdb *raw = (struct raw_mdb *)hfs_buffer_data(mdb->buf); hfs_put_ns(mdb->attrib, raw->drAtrb); hfs_buffer_dirty(mdb->buf); } /* free the buffers holding the primary and alternate MDBs */ hfs_buffer_put(mdb->buf); hfs_buffer_put(mdb->alt_buf); /* free the MDB */ HFS_DELETE(mdb); } |