The Tor Browser: netwerk/cache/nsDiskCacheBlockFile.cpp@6474c204b198 (annotated)

netwerk/cache/nsDiskCacheBlockFile.cpp@6474c204b198 (annotated)

netwerk/cache/nsDiskCacheBlockFile.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "nsCache.h"
 #include "nsDiskCache.h"
 #include "nsDiskCacheBlockFile.h"
 #include "mozilla/FileUtils.h"
 #include "mozilla/MemoryReporting.h"
 #include <algorithm>
 using namespace mozilla;
 /******************************************************************************
  * nsDiskCacheBlockFile -
  *****************************************************************************/
 /******************************************************************************
  *  Open
  *****************************************************************************/
 nsresult
 nsDiskCacheBlockFile::Open(nsIFile * blockFile,
                            uint32_t  blockSize,
                            uint32_t  bitMapSize,
                            nsDiskCache::CorruptCacheInfo *  corruptInfo)
 {
     NS_ENSURE_ARG_POINTER(corruptInfo);
     *corruptInfo = nsDiskCache::kUnexpectedError;
     if (bitMapSize % 32) {
         *corruptInfo = nsDiskCache::kInvalidArgPointer;
         return NS_ERROR_INVALID_ARG;
     }
     mBlockSize = blockSize;
     mBitMapWords = bitMapSize / 32;
     uint32_t bitMapBytes = mBitMapWords * 4;
     // open the file - restricted to user, the data could be confidential
     nsresult rv = blockFile->OpenNSPRFileDesc(PR_RDWR | PR_CREATE_FILE, 00600, &mFD);
     if (NS_FAILED(rv)) {
         *corruptInfo = nsDiskCache::kCouldNotCreateBlockFile;
         CACHE_LOG_DEBUG(("CACHE: nsDiskCacheBlockFile::Open "
                          "[this=%p] unable to open or create file: %d",
                          this, rv));
         return rv;  // unable to open or create file
     }
     // allocate bit map buffer
     mBitMap = new uint32_t[mBitMapWords];
     // check if we just creating the file
     mFileSize = PR_Available(mFD);
     if (mFileSize < 0) {
         // XXX an error occurred. We could call PR_GetError(), but how would that help?
         *corruptInfo = nsDiskCache::kBlockFileSizeError;
         rv = NS_ERROR_UNEXPECTED;
         goto error_exit;
     }
     if (mFileSize == 0) {
         // initialize bit map and write it
         memset(mBitMap, 0, bitMapBytes);
         if (!Write(0, mBitMap, bitMapBytes)) {
             *corruptInfo = nsDiskCache::kBlockFileBitMapWriteError;
             goto error_exit;
         }
     } else if ((uint32_t)mFileSize < bitMapBytes) {
         *corruptInfo = nsDiskCache::kBlockFileSizeLessThanBitMap;
         rv = NS_ERROR_UNEXPECTED;  // XXX NS_ERROR_CACHE_INVALID;
         goto error_exit;
     } else {
         // read the bit map
         const int32_t bytesRead = PR_Read(mFD, mBitMap, bitMapBytes);
         if ((bytesRead < 0) || ((uint32_t)bytesRead < bitMapBytes)) {
             *corruptInfo = nsDiskCache::kBlockFileBitMapReadError;
             rv = NS_ERROR_UNEXPECTED;
             goto error_exit;
         }
 #if defined(IS_LITTLE_ENDIAN)
         // Swap from network format
         for (unsigned int i = 0; i < mBitMapWords; ++i)
             mBitMap[i] = ntohl(mBitMap[i]);
 #endif
         // validate block file size
         // Because not whole blocks are written, the size may be a
         // little bit smaller than used blocks times blocksize,
         // because the last block will generally not be 'whole'.
         const uint32_t  estimatedSize = CalcBlockFileSize();
         if ((uint32_t)mFileSize + blockSize < estimatedSize) {
             *corruptInfo = nsDiskCache::kBlockFileEstimatedSizeError;
             rv = NS_ERROR_UNEXPECTED;
             goto error_exit;
         }
     }
     CACHE_LOG_DEBUG(("CACHE: nsDiskCacheBlockFile::Open [this=%p] succeeded",
                       this));
     return NS_OK;
 error_exit:
     CACHE_LOG_DEBUG(("CACHE: nsDiskCacheBlockFile::Open [this=%p] failed with "
                      "error %d", this, rv));
     Close(false);
     return rv;
 }
 /******************************************************************************
  *  Close
  *****************************************************************************/
 nsresult
 nsDiskCacheBlockFile::Close(bool flush)
 {
     nsresult rv = NS_OK;
     if (mFD) {
         if (flush)
             rv  = FlushBitMap();
         PRStatus err = PR_Close(mFD);
         if (NS_SUCCEEDED(rv) && (err != PR_SUCCESS))
             rv = NS_ERROR_UNEXPECTED;
         mFD = nullptr;
     }
      if (mBitMap) {
          delete [] mBitMap;
          mBitMap = nullptr;
      }
     return rv;
 }
 /******************************************************************************
  *  AllocateBlocks
  *
  *  Allocates 1-4 blocks, using a first fit strategy,
  *  so that no group of blocks spans a quad block boundary.
  *
  *  Returns block number of first block allocated or -1 on failure.
  *
  *****************************************************************************/
 int32_t
 nsDiskCacheBlockFile::AllocateBlocks(int32_t numBlocks)
 {
     const int maxPos = 32 - numBlocks;
     const uint32_t mask = (0x01 << numBlocks) - 1;
     for (unsigned int i = 0; i < mBitMapWords; ++i) {
         uint32_t mapWord = ~mBitMap[i]; // flip bits so free bits are 1
         if (mapWord) {                  // At least one free bit
             // Binary search for first free bit in word
             int bit = 0;
             if ((mapWord & 0x0FFFF) == 0) { bit |= 16; mapWord >>= 16; }
             if ((mapWord & 0x000FF) == 0) { bit |= 8;  mapWord >>= 8;  }
             if ((mapWord & 0x0000F) == 0) { bit |= 4;  mapWord >>= 4;  }
             if ((mapWord & 0x00003) == 0) { bit |= 2;  mapWord >>= 2;  }
             if ((mapWord & 0x00001) == 0) { bit |= 1;  mapWord >>= 1;  }
             // Find first fit for mask
             for (; bit <= maxPos; ++bit) {
                 // all bits selected by mask are 1, so free
                 if ((mask & mapWord) == mask) {
                     mBitMap[i] |= mask << bit;
                     mBitMapDirty = true;
                     return (int32_t)i * 32 + bit;
                 }
             }
         }
     }
     return -1;
 }
 /******************************************************************************
  *  DeallocateBlocks
  *****************************************************************************/
 nsresult
 nsDiskCacheBlockFile::DeallocateBlocks( int32_t  startBlock, int32_t  numBlocks)
 {
     if (!mFD)  return NS_ERROR_NOT_AVAILABLE;
     if ((startBlock < 0) || ((uint32_t)startBlock > mBitMapWords * 32 - 1) ||
         (numBlocks < 1)  || (numBlocks > 4))
        return NS_ERROR_ILLEGAL_VALUE;
     const int32_t startWord = startBlock >> 5;      // Divide by 32
     const uint32_t startBit = startBlock & 31;      // Modulo by 32
     // make sure requested deallocation doesn't span a word boundary
     if (startBit + numBlocks > 32)  return NS_ERROR_UNEXPECTED;
     uint32_t mask = ((0x01 << numBlocks) - 1) << startBit;
     // make sure requested deallocation is currently allocated
     if ((mBitMap[startWord] & mask) != mask)    return NS_ERROR_ABORT;
     mBitMap[startWord] ^= mask;    // flips the bits off;
     mBitMapDirty = true;
     // XXX rv = FlushBitMap();  // coherency vs. performance
     return NS_OK;
 }
 /******************************************************************************
  *  WriteBlocks
  *****************************************************************************/
 nsresult
 nsDiskCacheBlockFile::WriteBlocks( void *   buffer,
                                    uint32_t size,
                                    int32_t  numBlocks,
                                    int32_t * startBlock)
 {
     // presume buffer != nullptr and startBlock != nullptr
     NS_ENSURE_TRUE(mFD, NS_ERROR_NOT_AVAILABLE);
     // allocate some blocks in the cache block file
     *startBlock = AllocateBlocks(numBlocks);
     if (*startBlock < 0)
         return NS_ERROR_NOT_AVAILABLE;
     // seek to block position
     int32_t blockPos = mBitMapWords * 4 + *startBlock * mBlockSize;
     // write the blocks
     return Write(blockPos, buffer, size) ? NS_OK : NS_ERROR_FAILURE;
 }
 /******************************************************************************
  *  ReadBlocks
  *****************************************************************************/
 nsresult
 nsDiskCacheBlockFile::ReadBlocks( void *    buffer,
                                   int32_t   startBlock,
                                   int32_t   numBlocks,
                                   int32_t * bytesRead)
 {
     // presume buffer != nullptr and bytesRead != bytesRead
     if (!mFD)  return NS_ERROR_NOT_AVAILABLE;
     nsresult rv = VerifyAllocation(startBlock, numBlocks);
     if (NS_FAILED(rv))  return rv;
     // seek to block position
     int32_t blockPos = mBitMapWords * 4 + startBlock * mBlockSize;
     int32_t filePos = PR_Seek(mFD, blockPos, PR_SEEK_SET);
     if (filePos != blockPos)  return NS_ERROR_UNEXPECTED;
     // read the blocks
     int32_t bytesToRead = *bytesRead;
     if ((bytesToRead <= 0) || ((uint32_t)bytesToRead > mBlockSize * numBlocks)) {
         bytesToRead = mBlockSize * numBlocks;
     }
     *bytesRead = PR_Read(mFD, buffer, bytesToRead);
     CACHE_LOG_DEBUG(("CACHE: nsDiskCacheBlockFile::Read [this=%p] "
                      "returned %d / %d bytes", this, *bytesRead, bytesToRead));
     return NS_OK;
 }
 /******************************************************************************
  *  FlushBitMap
  *****************************************************************************/
 nsresult
 nsDiskCacheBlockFile::FlushBitMap()
 {
     if (!mBitMapDirty)  return NS_OK;
 #if defined(IS_LITTLE_ENDIAN)
     uint32_t *bitmap = new uint32_t[mBitMapWords];
     // Copy and swap to network format
     uint32_t *p = bitmap;
     for (unsigned int i = 0; i < mBitMapWords; ++i, ++p)
       *p = htonl(mBitMap[i]);
 #else
     uint32_t *bitmap = mBitMap;
 #endif
     // write bitmap
     bool written = Write(0, bitmap, mBitMapWords * 4);
 #if defined(IS_LITTLE_ENDIAN)
     delete [] bitmap;
 #endif
     if (!written)
         return NS_ERROR_UNEXPECTED;
     PRStatus err = PR_Sync(mFD);
     if (err != PR_SUCCESS)  return NS_ERROR_UNEXPECTED;
     mBitMapDirty = false;
     return NS_OK;
 }
 /******************************************************************************
  *  VerifyAllocation
  *
  *  Return values:
  *      NS_OK if all bits are marked allocated
  *      NS_ERROR_ILLEGAL_VALUE if parameters don't obey constraints
  *      NS_ERROR_FAILURE if some or all the bits are marked unallocated
  *
  *****************************************************************************/
 nsresult
 nsDiskCacheBlockFile::VerifyAllocation( int32_t  startBlock, int32_t  numBlocks)
 {
     if ((startBlock < 0) || ((uint32_t)startBlock > mBitMapWords * 32 - 1) ||
         (numBlocks < 1)  || (numBlocks > 4))
        return NS_ERROR_ILLEGAL_VALUE;
     const int32_t startWord = startBlock >> 5;      // Divide by 32
     const uint32_t startBit = startBlock & 31;      // Modulo by 32
     // make sure requested deallocation doesn't span a word boundary
     if (startBit + numBlocks > 32)  return NS_ERROR_ILLEGAL_VALUE;
     uint32_t mask = ((0x01 << numBlocks) - 1) << startBit;
     // check if all specified blocks are currently allocated
     if ((mBitMap[startWord] & mask) != mask)    return NS_ERROR_FAILURE;
     return NS_OK;
 }
 /******************************************************************************
  *  CalcBlockFileSize
  *
  *  Return size of the block file according to the bits set in mBitmap
  *
  *****************************************************************************/
 uint32_t
 nsDiskCacheBlockFile::CalcBlockFileSize()
 {
     // search for last byte in mBitMap with allocated bits
     uint32_t  estimatedSize = mBitMapWords * 4;
     int32_t   i = mBitMapWords;
     while (--i >= 0) {
         if (mBitMap[i]) break;
     }
     if (i >= 0) {
         // binary search to find last allocated bit in byte
         uint32_t mapWord = mBitMap[i];
         uint32_t lastBit = 31;
         if ((mapWord & 0xFFFF0000) == 0) { lastBit ^= 16; mapWord <<= 16; }
         if ((mapWord & 0xFF000000) == 0) { lastBit ^= 8; mapWord <<= 8; }
         if ((mapWord & 0xF0000000) == 0) { lastBit ^= 4; mapWord <<= 4; }
         if ((mapWord & 0xC0000000) == 0) { lastBit ^= 2; mapWord <<= 2; }
         if ((mapWord & 0x80000000) == 0) { lastBit ^= 1; mapWord <<= 1; }
         estimatedSize +=  (i * 32 + lastBit + 1) * mBlockSize;
     }
     return estimatedSize;
 }
 /******************************************************************************
  *  Write
  *
  *  Wrapper around PR_Write that grows file in larger chunks to combat fragmentation
  *
  *****************************************************************************/
 bool
 nsDiskCacheBlockFile::Write(int32_t offset, const void *buf, int32_t amount)
 {
     /* Grow the file to 4mb right away, then double it until the file grows to 20mb.
 mb is a magic threshold because OSX stops autodefragging files bigger than that.
        Beyond 20mb grow in 4mb chunks.
      */
     const int32_t upTo = offset + amount;
     // Use a conservative definition of 20MB
     const int32_t minPreallocate = 4*1024*1024;
     const int32_t maxPreallocate = 20*1000*1000;
     if (mFileSize < upTo) {
         // maximal file size
         const int32_t maxFileSize = mBitMapWords * 4 * (mBlockSize * 8 + 1);
         if (upTo > maxPreallocate) {
             // grow the file as a multiple of minPreallocate
             mFileSize = ((upTo + minPreallocate - 1) / minPreallocate) * minPreallocate;
         } else {
             // Grow quickly between 1MB to 20MB
             if (mFileSize)
                 while(mFileSize < upTo)
                     mFileSize *= 2;
             mFileSize = clamped(mFileSize, minPreallocate, maxPreallocate);
         }
         mFileSize = std::min(mFileSize, maxFileSize);
 #if !defined(XP_MACOSX)
         mozilla::fallocate(mFD, mFileSize);
 #endif
     }
     if (PR_Seek(mFD, offset, PR_SEEK_SET) != offset)
         return false;
     return PR_Write(mFD, buf, amount) == amount;
 }
 size_t
 nsDiskCacheBlockFile::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf)
 {
     return aMallocSizeOf(mBitMap) + aMallocSizeOf(mFD);
 }

The Tor Browser / annotate

netwerk/cache/nsDiskCacheBlockFile.cpp@6474c204b198 (annotated)

netwerk/cache/nsDiskCacheBlockFile.cpp