1 // SuperBlock.cpp 2 // 3 // Copyright (c) 2003, Ingo Weinhold (bonefish@cs.tu-berlin.de) 4 // 5 // This program is free software; you can redistribute it and/or modify 6 // it under the terms of the GNU General Public License as published by 7 // the Free Software Foundation; either version 2 of the License, or 8 // (at your option) any later version. 9 // 10 // This program is distributed in the hope that it will be useful, 11 // but WITHOUT ANY WARRANTY; without even the implied warranty of 12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 // GNU General Public License for more details. 14 // 15 // You should have received a copy of the GNU General Public License 16 // along with this program; if not, write to the Free Software 17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 // 19 // You can alternatively use *this file* under the terms of the the MIT 20 // license included in this package. 21 22 #include <new> 23 #include <string.h> 24 #include <unistd.h> 25 26 #include "Debug.h" 27 #include "SuperBlock.h" 28 29 using std::nothrow; 30 31 /*! 32 \class DirEntry 33 \brief Represents the on-disk structure for super block of the FS. 34 35 There exist two versions of the structure and this class can deal with both 36 of them. This class can also handle a very old layout that puts the super 37 block in a different location. The Init() methods tries to find and read 38 the super block from disk. 39 */ 40 41 // read_super_block 42 template<typename super_block_t> 43 static 44 status_t 45 read_super_block(int device, off_t offset, const char *magic, 46 super_block_t **_superBlock) 47 { 48 super_block_t *superBlock = NULL; 49 status_t error = B_OK; 50 // allocate memory for the super block 51 if (error == B_OK) { 52 superBlock = new(nothrow) super_block_t; 53 if (!superBlock) 54 error = B_NO_MEMORY; 55 } 56 // read the super block 57 if (error == B_OK) { 58 size_t size = sizeof(super_block_t); 59 if (read_pos(device, offset, superBlock, size) != (int32)size) 60 error = B_IO_ERROR; 61 } 62 // check magic 63 if (error == B_OK) { 64 size_t len = strlen(magic); 65 if (strncmp(superBlock->s_magic, magic, len)) 66 error = B_ERROR; 67 } 68 // set result / cleanup on failure 69 if (error == B_OK) 70 *_superBlock = superBlock; 71 else if (superBlock) 72 delete superBlock; 73 return error; 74 } 75 76 // constructor 77 SuperBlock::SuperBlock() 78 : fFormatVersion(REISERFS_3_6), 79 fCurrentData(NULL) 80 { 81 } 82 83 // destructor 84 SuperBlock::~SuperBlock() 85 { 86 if (GetFormatVersion() == REISERFS_3_6) { 87 if (fCurrentData) 88 delete fCurrentData; 89 } else { 90 if (fOldData) 91 delete fOldData; 92 } 93 } 94 95 // Init 96 status_t 97 SuperBlock::Init(int device, off_t offset) 98 { 99 status_t error = B_OK; 100 // try old version and old layout 101 if (read_super_block(device, REISERFS_OLD_DISK_OFFSET_IN_BYTES + offset, 102 REISERFS_SUPER_MAGIC_STRING, &fOldData) == B_OK) { 103 PRINT(("SuperBlock: ReiserFS 3.5 (old layout)\n")); 104 fFormatVersion = REISERFS_3_5; 105 // try old version and new layout 106 } else if (read_super_block(device, REISERFS_DISK_OFFSET_IN_BYTES + offset, 107 REISERFS_SUPER_MAGIC_STRING, &fOldData) == B_OK) { 108 PRINT(("SuperBlock: ReiserFS 3.5\n")); 109 fFormatVersion = REISERFS_3_5; 110 // try new version and new layout 111 } else if (read_super_block(device, REISERFS_DISK_OFFSET_IN_BYTES + offset, 112 REISER2FS_SUPER_MAGIC_STRING, &fOldData) == B_OK) { 113 PRINT(("SuperBlock: ReiserFS 3.6\n")); 114 fFormatVersion = REISERFS_3_6; 115 // failure 116 } else 117 error = B_ERROR; 118 // TODO: checks... 119 return error; 120 } 121 122