The Tor Browser: xpcom/io/nsUnicharInputStream.cpp@97036ab72558 (annotated)

xpcom/io/nsUnicharInputStream.cpp@97036ab72558 (annotated)

xpcom/io/nsUnicharInputStream.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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 "nsUnicharInputStream.h"
 #include "nsIInputStream.h"
 #include "nsIServiceManager.h"
 #include "nsString.h"
 #include "nsTArray.h"
 #include "nsAutoPtr.h"
 #include "nsCRT.h"
 #include "nsStreamUtils.h"
 #include "nsUTF8Utils.h"
 #include "mozilla/Attributes.h"
 #include <fcntl.h>
 #if defined(XP_WIN)
 #include <io.h>
 #else
 #include <unistd.h>
 #endif
 #define STRING_BUFFER_SIZE 8192
 class StringUnicharInputStream MOZ_FINAL : public nsIUnicharInputStream {
 public:
   StringUnicharInputStream(const nsAString& aString) :
     mString(aString), mPos(0), mLen(aString.Length()) { }
   NS_DECL_ISUPPORTS
   NS_DECL_NSIUNICHARINPUTSTREAM
   nsString mString;
   uint32_t mPos;
   uint32_t mLen;
 private:
   ~StringUnicharInputStream() { }
 };
 NS_IMETHODIMP
 StringUnicharInputStream::Read(char16_t* aBuf,
                                uint32_t aCount,
                                uint32_t *aReadCount)
 {
   if (mPos >= mLen) {
     *aReadCount = 0;
     return NS_OK;
   }
   nsAString::const_iterator iter;
   mString.BeginReading(iter);
   const char16_t* us = iter.get();
   uint32_t amount = mLen - mPos;
   if (amount > aCount) {
     amount = aCount;
   }
   memcpy(aBuf, us + mPos, sizeof(char16_t) * amount);
   mPos += amount;
   *aReadCount = amount;
   return NS_OK;
 }
 NS_IMETHODIMP
 StringUnicharInputStream::ReadSegments(nsWriteUnicharSegmentFun aWriter,
                                        void* aClosure,
                                        uint32_t aCount, uint32_t *aReadCount)
 {
   uint32_t bytesWritten;
   uint32_t totalBytesWritten = 0;
   nsresult rv;
   aCount = XPCOM_MIN(mString.Length() - mPos, aCount);
   nsAString::const_iterator iter;
   mString.BeginReading(iter);
   while (aCount) {
     rv = aWriter(this, aClosure, iter.get() + mPos,
                  totalBytesWritten, aCount, &bytesWritten);
     if (NS_FAILED(rv)) {
       // don't propagate errors to the caller
       break;
     }
     aCount -= bytesWritten;
     totalBytesWritten += bytesWritten;
     mPos += bytesWritten;
   }
   *aReadCount = totalBytesWritten;
   return NS_OK;
 }
 NS_IMETHODIMP
 StringUnicharInputStream::ReadString(uint32_t aCount, nsAString& aString,
                                      uint32_t* aReadCount)
 {
   if (mPos >= mLen) {
     *aReadCount = 0;
     return NS_OK;
   }
   uint32_t amount = mLen - mPos;
   if (amount > aCount) {
     amount = aCount;
   }
   aString = Substring(mString, mPos, amount);
   mPos += amount;
   *aReadCount = amount;
   return NS_OK;
 }
 nsresult StringUnicharInputStream::Close()
 {
   mPos = mLen;
   return NS_OK;
 }
 NS_IMPL_ISUPPORTS(StringUnicharInputStream, nsIUnicharInputStream)
 //----------------------------------------------------------------------
 class UTF8InputStream MOZ_FINAL : public nsIUnicharInputStream {
 public:
   UTF8InputStream();
   nsresult Init(nsIInputStream* aStream);
   NS_DECL_ISUPPORTS
   NS_DECL_NSIUNICHARINPUTSTREAM
 private:
   ~UTF8InputStream();
 protected:
   int32_t Fill(nsresult * aErrorCode);
   static void CountValidUTF8Bytes(const char *aBuf, uint32_t aMaxBytes, uint32_t& aValidUTF8bytes, uint32_t& aValidUTF16CodeUnits);
   nsCOMPtr<nsIInputStream> mInput;
   FallibleTArray<char> mByteData;
   FallibleTArray<char16_t> mUnicharData;
   uint32_t mByteDataOffset;
   uint32_t mUnicharDataOffset;
   uint32_t mUnicharDataLength;
 };
 UTF8InputStream::UTF8InputStream() :
   mByteDataOffset(0),
   mUnicharDataOffset(0),
   mUnicharDataLength(0)
 {
 }
 nsresult
 UTF8InputStream::Init(nsIInputStream* aStream)
 {
   if (!mByteData.SetCapacity(STRING_BUFFER_SIZE) ||
       !mUnicharData.SetCapacity(STRING_BUFFER_SIZE)) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
   mInput = aStream;
   return NS_OK;
 }
 NS_IMPL_ISUPPORTS(UTF8InputStream,nsIUnicharInputStream)
 UTF8InputStream::~UTF8InputStream()
 {
   Close();
 }
 nsresult UTF8InputStream::Close()
 {
   mInput = nullptr;
   mByteData.Clear();
   mUnicharData.Clear();
   return NS_OK;
 }
 nsresult UTF8InputStream::Read(char16_t* aBuf,
                                uint32_t aCount,
                                uint32_t *aReadCount)
 {
   NS_ASSERTION(mUnicharDataLength >= mUnicharDataOffset, "unsigned madness");
   uint32_t readCount = mUnicharDataLength - mUnicharDataOffset;
   nsresult errorCode;
   if (0 == readCount) {
     // Fill the unichar buffer
     int32_t bytesRead = Fill(&errorCode);
     if (bytesRead <= 0) {
       *aReadCount = 0;
       return errorCode;
     }
     readCount = bytesRead;
   }
   if (readCount > aCount) {
     readCount = aCount;
   }
   memcpy(aBuf, mUnicharData.Elements() + mUnicharDataOffset,
          readCount * sizeof(char16_t));
   mUnicharDataOffset += readCount;
   *aReadCount = readCount;
   return NS_OK;
 }
 NS_IMETHODIMP
 UTF8InputStream::ReadSegments(nsWriteUnicharSegmentFun aWriter,
                               void* aClosure,
                               uint32_t aCount, uint32_t *aReadCount)
 {
   NS_ASSERTION(mUnicharDataLength >= mUnicharDataOffset, "unsigned madness");
   uint32_t bytesToWrite = mUnicharDataLength - mUnicharDataOffset;
   nsresult rv = NS_OK;
   if (0 == bytesToWrite) {
     // Fill the unichar buffer
     int32_t bytesRead = Fill(&rv);
     if (bytesRead <= 0) {
       *aReadCount = 0;
       return rv;
     }
     bytesToWrite = bytesRead;
   }
   if (bytesToWrite > aCount)
     bytesToWrite = aCount;
   uint32_t bytesWritten;
   uint32_t totalBytesWritten = 0;
   while (bytesToWrite) {
     rv = aWriter(this, aClosure,
                  mUnicharData.Elements() + mUnicharDataOffset,
                  totalBytesWritten, bytesToWrite, &bytesWritten);
     if (NS_FAILED(rv)) {
       // don't propagate errors to the caller
       break;
     }
     bytesToWrite -= bytesWritten;
     totalBytesWritten += bytesWritten;
     mUnicharDataOffset += bytesWritten;
   }
   *aReadCount = totalBytesWritten;
   return NS_OK;
 }
 NS_IMETHODIMP
 UTF8InputStream::ReadString(uint32_t aCount, nsAString& aString,
                             uint32_t* aReadCount)
 {
   NS_ASSERTION(mUnicharDataLength >= mUnicharDataOffset, "unsigned madness");
   uint32_t readCount = mUnicharDataLength - mUnicharDataOffset;
   nsresult errorCode;
   if (0 == readCount) {
     // Fill the unichar buffer
     int32_t bytesRead = Fill(&errorCode);
     if (bytesRead <= 0) {
       *aReadCount = 0;
       return errorCode;
     }
     readCount = bytesRead;
   }
   if (readCount > aCount) {
     readCount = aCount;
   }
   const char16_t* buf = mUnicharData.Elements() + mUnicharDataOffset;
   aString.Assign(buf, readCount);
   mUnicharDataOffset += readCount;
   *aReadCount = readCount;
   return NS_OK;
 }
 int32_t UTF8InputStream::Fill(nsresult * aErrorCode)
 {
   if (nullptr == mInput) {
     // We already closed the stream!
     *aErrorCode = NS_BASE_STREAM_CLOSED;
     return -1;
   }
   NS_ASSERTION(mByteData.Length() >= mByteDataOffset, "unsigned madness");
   uint32_t remainder = mByteData.Length() - mByteDataOffset;
   mByteDataOffset = remainder;
   uint32_t nb;
   *aErrorCode = NS_FillArray(mByteData, mInput, remainder, &nb);
   if (nb == 0) {
     // Because we assume a many to one conversion, the lingering data
     // in the byte buffer must be a partial conversion
     // fragment. Because we know that we have received no more new
     // data to add to it, we can't convert it. Therefore, we discard
     // it.
     return nb;
   }
   NS_ASSERTION(remainder + nb == mByteData.Length(), "bad nb");
   // Now convert as much of the byte buffer to unicode as possible
   uint32_t srcLen, dstLen;
   CountValidUTF8Bytes(mByteData.Elements(),remainder + nb, srcLen, dstLen);
   // the number of UCS2 characters should always be <= the number of
   // UTF8 chars
   NS_ASSERTION( (remainder+nb >= srcLen), "cannot be longer than out buffer");
   NS_ASSERTION(dstLen <= mUnicharData.Capacity(),
                "Ouch. I would overflow my buffer if I wasn't so careful.");
   if (dstLen > mUnicharData.Capacity()) return 0;
   ConvertUTF8toUTF16 converter(mUnicharData.Elements());
   nsASingleFragmentCString::const_char_iterator start = mByteData.Elements();
   nsASingleFragmentCString::const_char_iterator end = mByteData.Elements() + srcLen;
   copy_string(start, end, converter);
   if (converter.Length() != dstLen) {
     *aErrorCode = NS_BASE_STREAM_BAD_CONVERSION;
     return -1;
   }
   mUnicharDataOffset = 0;
   mUnicharDataLength = dstLen;
   mByteDataOffset = srcLen;
   return dstLen;
 }
 void
 UTF8InputStream::CountValidUTF8Bytes(const char* aBuffer, uint32_t aMaxBytes, uint32_t& aValidUTF8bytes, uint32_t& aValidUTF16CodeUnits)
 {
   const char *c = aBuffer;
   const char *end = aBuffer + aMaxBytes;
   const char *lastchar = c;     // pre-initialize in case of 0-length buffer
   uint32_t utf16length = 0;
   while (c < end && *c) {
     lastchar = c;
     utf16length++;
     if (UTF8traits::isASCII(*c))
       c++;
     else if (UTF8traits::is2byte(*c))
       c += 2;
     else if (UTF8traits::is3byte(*c))
       c += 3;
     else if (UTF8traits::is4byte(*c)) {
       c += 4;
       utf16length++; // add 1 more because this will be converted to a
                      // surrogate pair.
     }
     else if (UTF8traits::is5byte(*c))
       c += 5;
     else if (UTF8traits::is6byte(*c))
       c += 6;
     else {
       NS_WARNING("Unrecognized UTF8 string in UTF8InputStream::CountValidUTF8Bytes()");
       break; // Otherwise we go into an infinite loop.  But what happens now?
     }
   }
   if (c > end) {
     c = lastchar;
     utf16length--;
   }
   aValidUTF8bytes = c - aBuffer;
   aValidUTF16CodeUnits = utf16length;
 }
 NS_IMPL_QUERY_INTERFACE(nsSimpleUnicharStreamFactory,
                         nsIFactory,
                         nsISimpleUnicharStreamFactory)
 NS_IMETHODIMP_(MozExternalRefCountType) nsSimpleUnicharStreamFactory::AddRef() { return 2; }
 NS_IMETHODIMP_(MozExternalRefCountType) nsSimpleUnicharStreamFactory::Release() { return 1; }
 NS_IMETHODIMP
 nsSimpleUnicharStreamFactory::CreateInstance(nsISupports* aOuter, REFNSIID aIID,
                                             void **aResult)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 NS_IMETHODIMP
 nsSimpleUnicharStreamFactory::LockFactory(bool aLock)
 {
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSimpleUnicharStreamFactory::CreateInstanceFromString(const nsAString& aString,
                                                       nsIUnicharInputStream* *aResult)
 {
   StringUnicharInputStream* it = new StringUnicharInputStream(aString);
   if (!it) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
   NS_ADDREF(*aResult = it);
   return NS_OK;
 }
 NS_IMETHODIMP
 nsSimpleUnicharStreamFactory::CreateInstanceFromUTF8Stream(nsIInputStream* aStreamToWrap,
                                                            nsIUnicharInputStream* *aResult)
 {
   *aResult = nullptr;
   // Create converter input stream
   nsRefPtr<UTF8InputStream> it = new UTF8InputStream();
   if (!it)
     return NS_ERROR_OUT_OF_MEMORY;
   nsresult rv = it->Init(aStreamToWrap);
   if (NS_FAILED(rv))
     return rv;
   NS_ADDREF(*aResult = it);
   return NS_OK;
 }
 nsSimpleUnicharStreamFactory*
 nsSimpleUnicharStreamFactory::GetInstance()
 {
   static const nsSimpleUnicharStreamFactory kInstance;
   return const_cast<nsSimpleUnicharStreamFactory*>(&kInstance);
 }

The Tor Browser / annotate

xpcom/io/nsUnicharInputStream.cpp@97036ab72558 (annotated)

xpcom/io/nsUnicharInputStream.cpp