wipefs.cpp

   1 /*
   2  * Copyright (c) 2008 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 //
  24 //      wipefs.cpp
  25 //
  26
  27 #include <fcntl.h>
  28 #include <sys/uio.h>
  29 #include <sys/ioctl.h>
  30 #include <sys/disk.h>
  31 #include <sys/stat.h>
  32
  33 #include "ExtentManager.h"
  34 #include "wipefs.h"
  35
  36 #define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))
  37
  38 struct __wipefs_ctx {
  39         int fd;
  40         class ExtentManager extMan;
  41 };
  42
  43 void
  44 AddExtentsForFutureFS(class ExtentManager *extMan)
  45 {
  46         // we don't know what blocks future FS will use to recognize itself.  But we'd better be safe than sorry and write
  47         // the first and last 2MB of the volume
  48         off_t size = 2 * 1024 * 1024;
  49         extMan->AddByteRangeExtent(0, size);
  50         extMan->AddByteRangeExtent(extMan->totalBytes - size, size);
  51 }
  52
  53 void
  54 AddExtentsForHFS(class ExtentManager *extMan)
  55 {
  56         // first 1KB is boot block, last 512B is reserved
  57         // the Volume Header (512B) is after 1KB and before the last 512B
  58         extMan->AddByteRangeExtent(0, 1024 + 512);
  59         extMan->AddByteRangeExtent(extMan->totalBytes - 1024, 1024);
  60 }
  61
  62 void
  63 AddExtentsForMSDOS(class ExtentManager *extMan)
  64 {
  65         // MSDOS needs the first block (in theory, up to 32KB)
  66         extMan->AddByteRangeExtent(0, 32 * 1024);
  67 }
  68
  69 void
  70 AddExtentsForNTFS(class ExtentManager *extMan)
  71 {
  72         // NTFS supports block size from 256B to 32768B.  The first, middle and last block are needed
  73         extMan->AddByteRangeExtent(0, 32 * 1024);
  74         extMan->AddByteRangeExtent(extMan->totalBytes - 32 * 1024, 32 * 1024);
  75         // to be safe, add the rage from (mid_point - 32KB) to (mid_point + 32KB)
  76         extMan->AddByteRangeExtent(extMan->totalBytes / 2 - 32 * 1024, 64 * 1024);
  77 }
  78
  79 void
  80 AddExtentsForUDF(class ExtentManager *extMan)
  81 {
  82         off_t lastBlockAddr = extMan->totalBlocks - 1;
  83
  84         // Volume Recognization Sequence (VRS) starts at 32KB, usually less than 7 Volume Structure Descriptors (2KB each)
  85         extMan->AddByteRangeExtent(32 * 1024, 14 * 1024);
  86
  87         // AVDP is on 256, 512, last block, last block - 256
  88         extMan->AddBlockRangeExtent(256, 1);
  89         extMan->AddBlockRangeExtent(512, 1);
  90         extMan->AddBlockRangeExtent(lastBlockAddr, 1);
  91         extMan->AddBlockRangeExtent(lastBlockAddr - 256, 1);
  92
  93         // to be safe, assume the device has 2KB block size and do it again
  94         if (extMan->blockSize != 2048) {
  95                 off_t blockSize = 2048;
  96                 // AVDP is on 256, 512, last block, last block - 256
  97                 extMan->AddByteRangeExtent(256 * blockSize, blockSize);
  98                 extMan->AddByteRangeExtent(512 * blockSize, blockSize);
  99                 extMan->AddByteRangeExtent(extMan->totalBytes - blockSize, blockSize);
 100                 extMan->AddByteRangeExtent(extMan->totalBytes - 256 * blockSize, blockSize);
 101         }
 102 }
 103
 104 void
 105 AddExtentsForUFS(class ExtentManager *extMan)
 106 {
 107         // UFS super block is 8KB at offset 8KB
 108         extMan->AddByteRangeExtent(8192, 8192);
 109 }
 110
 111 void
 112 AddExtentsForZFS(class ExtentManager *extMan)
 113 {
 114         // ZFS needs the first 512KB and last 512KB for all the 4 disk labels
 115         extMan->AddByteRangeExtent(0, 512 * 1024);
 116         extMan->AddByteRangeExtent(extMan->totalBytes - 512 * 1024, 512 * 1024);
 117 }
 118
 119 void
 120 AddExtentsForPartitions(class ExtentManager *extMan)
 121 {
 122         // MBR (Master Boot Record) needs the first sector
 123         // APM (Apple Partition Map) needs the second sector
 124         // GPT (GUID Partition Table) needs the first 34 and last 33 sectors
 125         extMan->AddByteRangeExtent(0, 512 * 34);
 126         extMan->AddByteRangeExtent(extMan->totalBytes - 512 * 33, 512 * 33);
 127 }
 128
 129 extern "C" int
 130 wipefs_alloc(int fd, size_t block_size, wipefs_ctx *handle)
 131 {
 132         int err = 0;
 133         uint64_t numBlocks = 0;
 134         uint32_t nativeBlockSize = 0;
 135         off_t totalSizeInBytes = 0;
 136         class ExtentManager *extMan = NULL;
 137         struct stat sbuf = { 0 };
 138
 139         *handle = NULL;
 140         (void)fstat(fd, &sbuf);
 141         switch (sbuf.st_mode & S_IFMT) {
 142         case S_IFCHR:
 143         case S_IFBLK:
 144                 if (ioctl(fd, DKIOCGETBLOCKSIZE, (char *)&nativeBlockSize) < 0) {
 145                         err = errno;
 146                         goto labelExit;
 147                 }
 148                 if (ioctl(fd, DKIOCGETBLOCKCOUNT, (char *)&numBlocks) < 0) {
 149                         err = errno;
 150                         goto labelExit;
 151                 }
 152                 totalSizeInBytes = numBlocks * nativeBlockSize;
 153                 break;
 154         case S_IFREG:
 155                 nativeBlockSize = sbuf.st_blksize;
 156                 numBlocks = sbuf.st_size / sbuf.st_blksize;
 157                 totalSizeInBytes = sbuf.st_size;
 158                 break;
 159         default:
 160                 errno = EINVAL;
 161                 goto labelExit;
 162         }
 163         if (block_size == 0) {
 164                 block_size = nativeBlockSize;
 165         }
 166         if (block_size == 0 || totalSizeInBytes == 0) {
 167                 err = EINVAL;
 168                 goto labelExit;
 169         }
 170
 171         try {
 172                 *handle = new __wipefs_ctx;
 173                 if (*handle == NULL) {
 174                         bad_alloc e;
 175                         throw e;
 176                 }
 177
 178                 (*handle)->fd = fd;
 179                 extMan = &(*handle)->extMan;
 180
 181                 extMan->Init(block_size, nativeBlockSize, totalSizeInBytes);
 182                 AddExtentsForFutureFS(extMan);
 183                 AddExtentsForHFS(extMan);
 184                 AddExtentsForMSDOS(extMan);
 185                 AddExtentsForNTFS(extMan);
 186                 AddExtentsForUDF(extMan);
 187                 AddExtentsForUFS(extMan);
 188                 AddExtentsForZFS(extMan);
 189                 AddExtentsForPartitions(extMan);
 190         }
 191         catch (bad_alloc &e) {
 192                 err = ENOMEM;
 193         }
 194         catch (...) { // currently only ENOMEM is possible
 195                 err = ENOMEM;
 196         }
 197
 198   labelExit:
 199         if (err != 0) {
 200                 wipefs_free(handle);
 201         }
 202         return err;
 203 } // wipefs_alloc
 204
 205 extern "C" int
 206 wipefs_except_blocks(wipefs_ctx handle, off_t block_offset, off_t nblocks)
 207 {
 208         int err = 0;
 209         try {
 210                 handle->extMan.RemoveBlockRangeExtent(block_offset, nblocks);
 211         }
 212         catch (bad_alloc &e) {
 213                 err = ENOMEM;
 214         }
 215         catch (...) { // currently only ENOMEM is possible
 216                 err = ENOMEM;
 217         }
 218         return err;
 219 }
 220
 221 extern "C" int
 222 wipefs_wipe(wipefs_ctx handle)
 223 {
 224         int err = 0;
 225         uint8_t *bufZero = NULL;
 226         ListExtIt curExt;
 227         size_t bufSize;
 228         dk_discard_t discard;
 229
 230         memset(&discard, 0, sizeof(dk_discard_t));
 231         discard.length = handle->extMan.totalBytes;
 232
 233         //
 234         // Don't bother to check the return value since this is mostly
 235         // informational for the lower-level drivers.
 236         //
 237         ioctl(handle->fd, DKIOCDISCARD, (caddr_t)&discard);
 238
 239
 240         bufSize = 256 * 1024; // issue large I/O to get better performance
 241         bufZero = new uint8_t[bufSize];
 242         bzero(bufZero, bufSize);
 243
 244         off_t byteOffset, totalBytes;
 245         size_t numBytes, numBytesToWrite, blockSize;
 246
 247         blockSize = handle->extMan.blockSize;
 248         totalBytes = handle->extMan.totalBytes;
 249         // write zero to all extents
 250         for (curExt = handle->extMan.extentList.begin(); curExt != handle->extMan.extentList.end(); curExt++) {
 251                 byteOffset = curExt->blockAddr * blockSize;
 252                 numBytes = curExt->numBlocks * blockSize;
 253                 // make both offset and numBytes on native block boundary
 254                 if (byteOffset % handle->extMan.nativeBlockSize != 0 ||
 255                         numBytes % handle->extMan.nativeBlockSize != 0) {
 256                         size_t nativeBlockSize = handle->extMan.nativeBlockSize;
 257                         off_t newOffset, newEndOffset;
 258                         newOffset = byteOffset / nativeBlockSize * nativeBlockSize;
 259                         newEndOffset = roundup(byteOffset + numBytes, nativeBlockSize);
 260                         byteOffset = newOffset;
 261                         numBytes = newEndOffset - newOffset;
 262                 }
 263                 if (byteOffset + (off_t)numBytes > totalBytes) {
 264                         numBytes = totalBytes - byteOffset;
 265                 }
 266                 while (numBytes > 0) {
 267                         numBytesToWrite = min(numBytes, bufSize);
 268                         if (pwrite(handle->fd, bufZero, numBytesToWrite, byteOffset) != (ssize_t)numBytesToWrite) {
 269                                 err = errno;
 270                                 goto labelExit;
 271                         }
 272                         numBytes -= numBytesToWrite;
 273                         byteOffset += numBytesToWrite;
 274                 }
 275         }
 276
 277   labelExit:
 278         if (bufZero != NULL)
 279                 delete[] bufZero;
 280         return err;
 281 } // wipefs_wipe
 282
 283 extern "C" void
 284 wipefs_free(wipefs_ctx *handle)
 285 {
 286         if (*handle != NULL) {
 287                 delete *handle;
 288                 *handle = NULL;
 289         }
 290 }