modules/libjar/zipwriter/nsZipWriter.cpp
author Jonathan Kingston <jkt@mozilla.com>
Wed, 27 Feb 2019 23:41:04 +0000
changeset 522438 b5f7ff4ca9b58d002c2bebe0a11b529680068b0c
parent 521716 d5643033fdd801efda790a2836a3e196e7ba442e
child 522439 c48f47f793c0f0d9b4acf2caf9324b8bd7a5a683
permissions -rw-r--r--
Bug 1525319 - Removing context from OnStartRequest r=valentin Differential Revision: https://phabricator.services.mozilla.com/D20769

/* 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 "nsZipWriter.h"

#include <algorithm>

#include "StreamFunctions.h"
#include "nsZipDataStream.h"
#include "nsISeekableStream.h"
#include "nsIAsyncStreamCopier.h"
#include "nsIStreamListener.h"
#include "nsIInputStreamPump.h"
#include "nsILoadInfo.h"
#include "nsComponentManagerUtils.h"
#include "nsMemory.h"
#include "nsError.h"
#include "nsStreamUtils.h"
#include "nsThreadUtils.h"
#include "nsNetUtil.h"
#include "nsIChannel.h"
#include "nsIFile.h"
#include "prio.h"

#define ZIP_EOCDR_HEADER_SIZE 22
#define ZIP_EOCDR_HEADER_SIGNATURE 0x06054b50

using namespace mozilla;

/**
 * nsZipWriter is used to create and add to zip files.
 * It is based on the spec available at
 * http://www.pkware.com/documents/casestudies/APPNOTE.TXT.
 *
 * The basic structure of a zip file created is slightly simpler than that
 * illustrated in the spec because certain features of the zip format are
 * unsupported:
 *
 * [local file header 1]
 * [file data 1]
 * .
 * .
 * .
 * [local file header n]
 * [file data n]
 * [central directory]
 * [end of central directory record]
 */
NS_IMPL_ISUPPORTS(nsZipWriter, nsIZipWriter, nsIRequestObserver)

nsZipWriter::nsZipWriter() : mCDSOffset(0), mCDSDirty(false), mInQueue(false) {}

nsZipWriter::~nsZipWriter() {
  if (mStream && !mInQueue) Close();
}

NS_IMETHODIMP nsZipWriter::GetComment(nsACString &aComment) {
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;

  aComment = mComment;
  return NS_OK;
}

NS_IMETHODIMP nsZipWriter::SetComment(const nsACString &aComment) {
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;

  mComment = aComment;
  mCDSDirty = true;
  return NS_OK;
}

NS_IMETHODIMP nsZipWriter::GetInQueue(bool *aInQueue) {
  *aInQueue = mInQueue;
  return NS_OK;
}

NS_IMETHODIMP nsZipWriter::GetFile(nsIFile **aFile) {
  if (!mFile) return NS_ERROR_NOT_INITIALIZED;

  nsCOMPtr<nsIFile> file;
  nsresult rv = mFile->Clone(getter_AddRefs(file));
  NS_ENSURE_SUCCESS(rv, rv);

  NS_ADDREF(*aFile = file);
  return NS_OK;
}

/*
 * Reads file entries out of an existing zip file.
 */
nsresult nsZipWriter::ReadFile(nsIFile *aFile) {
  int64_t size;
  nsresult rv = aFile->GetFileSize(&size);
  NS_ENSURE_SUCCESS(rv, rv);

  // If the file is too short, it cannot be a valid archive, thus we fail
  // without even attempting to open it
  NS_ENSURE_TRUE(size > ZIP_EOCDR_HEADER_SIZE, NS_ERROR_FILE_CORRUPTED);

  nsCOMPtr<nsIInputStream> inputStream;
  rv = NS_NewLocalFileInputStream(getter_AddRefs(inputStream), aFile);
  NS_ENSURE_SUCCESS(rv, rv);

  uint8_t buf[1024];
  int64_t seek = size - 1024;
  uint32_t length = 1024;

  nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(inputStream);

  while (true) {
    if (seek < 0) {
      length += (int32_t)seek;
      seek = 0;
    }

    rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, seek);
    if (NS_FAILED(rv)) {
      inputStream->Close();
      return rv;
    }
    rv = ZW_ReadData(inputStream, (char *)buf, length);
    if (NS_FAILED(rv)) {
      inputStream->Close();
      return rv;
    }

    /*
     * We have to backtrack from the end of the file until we find the
     * CDS signature
     */
    // We know it's at least this far from the end
    for (uint32_t pos = length - ZIP_EOCDR_HEADER_SIZE; (int32_t)pos >= 0;
         pos--) {
      uint32_t sig = PEEK32(buf + pos);
      if (sig == ZIP_EOCDR_HEADER_SIGNATURE) {
        // Skip down to entry count
        pos += 10;
        uint32_t entries = READ16(buf, &pos);
        // Skip past CDS size
        pos += 4;
        mCDSOffset = READ32(buf, &pos);
        uint32_t commentlen = READ16(buf, &pos);

        if (commentlen == 0)
          mComment.Truncate();
        else if (pos + commentlen <= length)
          mComment.Assign((const char *)buf + pos, commentlen);
        else {
          if ((seek + pos + commentlen) > size) {
            inputStream->Close();
            return NS_ERROR_FILE_CORRUPTED;
          }
          auto field = MakeUnique<char[]>(commentlen);
          NS_ENSURE_TRUE(field, NS_ERROR_OUT_OF_MEMORY);
          rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, seek + pos);
          if (NS_FAILED(rv)) {
            inputStream->Close();
            return rv;
          }
          rv = ZW_ReadData(inputStream, field.get(), length);
          if (NS_FAILED(rv)) {
            inputStream->Close();
            return rv;
          }
          mComment.Assign(field.get(), commentlen);
        }

        rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, mCDSOffset);
        if (NS_FAILED(rv)) {
          inputStream->Close();
          return rv;
        }

        for (uint32_t entry = 0; entry < entries; entry++) {
          nsZipHeader *header = new nsZipHeader();
          if (!header) {
            inputStream->Close();
            mEntryHash.Clear();
            mHeaders.Clear();
            return NS_ERROR_OUT_OF_MEMORY;
          }
          rv = header->ReadCDSHeader(inputStream);
          if (NS_FAILED(rv)) {
            inputStream->Close();
            mEntryHash.Clear();
            mHeaders.Clear();
            return rv;
          }
          mEntryHash.Put(header->mName, mHeaders.Count());
          if (!mHeaders.AppendObject(header)) return NS_ERROR_OUT_OF_MEMORY;
        }

        return inputStream->Close();
      }
    }

    if (seek == 0) {
      // We've reached the start with no signature found. Corrupt.
      inputStream->Close();
      return NS_ERROR_FILE_CORRUPTED;
    }

    // Overlap by the size of the end of cdr
    seek -= (1024 - ZIP_EOCDR_HEADER_SIZE);
  }
  // Will never reach here in reality
  MOZ_ASSERT_UNREACHABLE("Loop should never complete");
  return NS_ERROR_UNEXPECTED;
}

NS_IMETHODIMP nsZipWriter::Open(nsIFile *aFile, int32_t aIoFlags) {
  if (mStream) return NS_ERROR_ALREADY_INITIALIZED;

  NS_ENSURE_ARG_POINTER(aFile);

  // Need to be able to write to the file
  if (aIoFlags & PR_RDONLY) return NS_ERROR_FAILURE;

  nsresult rv = aFile->Clone(getter_AddRefs(mFile));
  NS_ENSURE_SUCCESS(rv, rv);

  bool exists;
  rv = mFile->Exists(&exists);
  NS_ENSURE_SUCCESS(rv, rv);
  if (!exists && !(aIoFlags & PR_CREATE_FILE)) return NS_ERROR_FILE_NOT_FOUND;

  if (exists && !(aIoFlags & (PR_TRUNCATE | PR_WRONLY))) {
    rv = ReadFile(mFile);
    NS_ENSURE_SUCCESS(rv, rv);
    mCDSDirty = false;
  } else {
    mCDSOffset = 0;
    mCDSDirty = true;
    mComment.Truncate();
  }

  // Silently drop PR_APPEND
  aIoFlags &= 0xef;

  nsCOMPtr<nsIOutputStream> stream;
  rv = NS_NewLocalFileOutputStream(getter_AddRefs(stream), mFile, aIoFlags);
  if (NS_FAILED(rv)) {
    mHeaders.Clear();
    mEntryHash.Clear();
    return rv;
  }

  rv = NS_NewBufferedOutputStream(getter_AddRefs(mStream), stream.forget(),
                                  64 * 1024);
  if (NS_FAILED(rv)) {
    mHeaders.Clear();
    mEntryHash.Clear();
    return rv;
  }

  if (mCDSOffset > 0) {
    rv = SeekCDS();
    NS_ENSURE_SUCCESS(rv, rv);
  }

  return NS_OK;
}

NS_IMETHODIMP nsZipWriter::GetEntry(const nsACString &aZipEntry,
                                    nsIZipEntry **_retval) {
  int32_t pos;
  if (mEntryHash.Get(aZipEntry, &pos))
    NS_ADDREF(*_retval = mHeaders[pos]);
  else
    *_retval = nullptr;

  return NS_OK;
}

NS_IMETHODIMP nsZipWriter::HasEntry(const nsACString &aZipEntry,
                                    bool *_retval) {
  *_retval = mEntryHash.Get(aZipEntry, nullptr);

  return NS_OK;
}

NS_IMETHODIMP nsZipWriter::AddEntryDirectory(const nsACString &aZipEntry,
                                             PRTime aModTime, bool aQueue) {
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;

  if (aQueue) {
    nsZipQueueItem item;
    item.mOperation = OPERATION_ADD;
    item.mZipEntry = aZipEntry;
    item.mModTime = aModTime;
    item.mPermissions = PERMISSIONS_DIR;
    if (!mQueue.AppendElement(item)) return NS_ERROR_OUT_OF_MEMORY;
    return NS_OK;
  }

  if (mInQueue) return NS_ERROR_IN_PROGRESS;
  return InternalAddEntryDirectory(aZipEntry, aModTime, PERMISSIONS_DIR);
}

NS_IMETHODIMP nsZipWriter::AddEntryFile(const nsACString &aZipEntry,
                                        int32_t aCompression, nsIFile *aFile,
                                        bool aQueue) {
  NS_ENSURE_ARG_POINTER(aFile);
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;

  nsresult rv;
  if (aQueue) {
    nsZipQueueItem item;
    item.mOperation = OPERATION_ADD;
    item.mZipEntry = aZipEntry;
    item.mCompression = aCompression;
    rv = aFile->Clone(getter_AddRefs(item.mFile));
    NS_ENSURE_SUCCESS(rv, rv);
    if (!mQueue.AppendElement(item)) return NS_ERROR_OUT_OF_MEMORY;
    return NS_OK;
  }

  if (mInQueue) return NS_ERROR_IN_PROGRESS;

  bool exists;
  rv = aFile->Exists(&exists);
  NS_ENSURE_SUCCESS(rv, rv);
  if (!exists) return NS_ERROR_FILE_NOT_FOUND;

  bool isdir;
  rv = aFile->IsDirectory(&isdir);
  NS_ENSURE_SUCCESS(rv, rv);

  PRTime modtime;
  rv = aFile->GetLastModifiedTime(&modtime);
  NS_ENSURE_SUCCESS(rv, rv);
  modtime *= PR_USEC_PER_MSEC;

  uint32_t permissions;
  rv = aFile->GetPermissions(&permissions);
  NS_ENSURE_SUCCESS(rv, rv);

  if (isdir) return InternalAddEntryDirectory(aZipEntry, modtime, permissions);

  if (mEntryHash.Get(aZipEntry, nullptr)) return NS_ERROR_FILE_ALREADY_EXISTS;

  nsCOMPtr<nsIInputStream> inputStream;
  rv = NS_NewLocalFileInputStream(getter_AddRefs(inputStream), aFile);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = AddEntryStream(aZipEntry, modtime, aCompression, inputStream, false,
                      permissions);
  NS_ENSURE_SUCCESS(rv, rv);

  return inputStream->Close();
}

NS_IMETHODIMP nsZipWriter::AddEntryChannel(const nsACString &aZipEntry,
                                           PRTime aModTime,
                                           int32_t aCompression,
                                           nsIChannel *aChannel, bool aQueue) {
  NS_ENSURE_ARG_POINTER(aChannel);
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;

  if (aQueue) {
    nsZipQueueItem item;
    item.mOperation = OPERATION_ADD;
    item.mZipEntry = aZipEntry;
    item.mModTime = aModTime;
    item.mCompression = aCompression;
    item.mPermissions = PERMISSIONS_FILE;
    item.mChannel = aChannel;
    if (!mQueue.AppendElement(item)) return NS_ERROR_OUT_OF_MEMORY;
    return NS_OK;
  }

  if (mInQueue) return NS_ERROR_IN_PROGRESS;
  if (mEntryHash.Get(aZipEntry, nullptr)) return NS_ERROR_FILE_ALREADY_EXISTS;

  nsCOMPtr<nsIInputStream> inputStream;
  nsresult rv =
      NS_MaybeOpenChannelUsingOpen(aChannel, getter_AddRefs(inputStream));

  NS_ENSURE_SUCCESS(rv, rv);

  rv = AddEntryStream(aZipEntry, aModTime, aCompression, inputStream, false,
                      PERMISSIONS_FILE);
  NS_ENSURE_SUCCESS(rv, rv);

  return inputStream->Close();
}

NS_IMETHODIMP nsZipWriter::AddEntryStream(const nsACString &aZipEntry,
                                          PRTime aModTime, int32_t aCompression,
                                          nsIInputStream *aStream,
                                          bool aQueue) {
  return AddEntryStream(aZipEntry, aModTime, aCompression, aStream, aQueue,
                        PERMISSIONS_FILE);
}

nsresult nsZipWriter::AddEntryStream(const nsACString &aZipEntry,
                                     PRTime aModTime, int32_t aCompression,
                                     nsIInputStream *aStream, bool aQueue,
                                     uint32_t aPermissions) {
  NS_ENSURE_ARG_POINTER(aStream);
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;

  if (aQueue) {
    nsZipQueueItem item;
    item.mOperation = OPERATION_ADD;
    item.mZipEntry = aZipEntry;
    item.mModTime = aModTime;
    item.mCompression = aCompression;
    item.mPermissions = aPermissions;
    item.mStream = aStream;
    if (!mQueue.AppendElement(item)) return NS_ERROR_OUT_OF_MEMORY;
    return NS_OK;
  }

  if (mInQueue) return NS_ERROR_IN_PROGRESS;
  if (mEntryHash.Get(aZipEntry, nullptr)) return NS_ERROR_FILE_ALREADY_EXISTS;

  RefPtr<nsZipHeader> header = new nsZipHeader();
  NS_ENSURE_TRUE(header, NS_ERROR_OUT_OF_MEMORY);
  header->Init(aZipEntry, aModTime, ZIP_ATTRS(aPermissions, ZIP_ATTRS_FILE),
               mCDSOffset);
  nsresult rv = header->WriteFileHeader(mStream);
  if (NS_FAILED(rv)) {
    SeekCDS();
    return rv;
  }

  RefPtr<nsZipDataStream> stream = new nsZipDataStream();
  if (!stream) {
    SeekCDS();
    return NS_ERROR_OUT_OF_MEMORY;
  }
  rv = stream->Init(this, mStream, header, aCompression);
  if (NS_FAILED(rv)) {
    SeekCDS();
    return rv;
  }

  rv = stream->ReadStream(aStream);
  if (NS_FAILED(rv)) SeekCDS();
  return rv;
}

NS_IMETHODIMP nsZipWriter::RemoveEntry(const nsACString &aZipEntry,
                                       bool aQueue) {
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;

  if (aQueue) {
    nsZipQueueItem item;
    item.mOperation = OPERATION_REMOVE;
    item.mZipEntry = aZipEntry;
    if (!mQueue.AppendElement(item)) return NS_ERROR_OUT_OF_MEMORY;
    return NS_OK;
  }

  if (mInQueue) return NS_ERROR_IN_PROGRESS;

  int32_t pos;
  if (mEntryHash.Get(aZipEntry, &pos)) {
    // Flush any remaining data before we seek.
    nsresult rv = mStream->Flush();
    NS_ENSURE_SUCCESS(rv, rv);
    if (pos < mHeaders.Count() - 1) {
      // This is not the last entry, pull back the data.
      nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(mStream);
      rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET,
                          mHeaders[pos]->mOffset);
      NS_ENSURE_SUCCESS(rv, rv);

      nsCOMPtr<nsIInputStream> inputStream;
      rv = NS_NewLocalFileInputStream(getter_AddRefs(inputStream), mFile);
      NS_ENSURE_SUCCESS(rv, rv);
      seekable = do_QueryInterface(inputStream);
      rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET,
                          mHeaders[pos + 1]->mOffset);
      if (NS_FAILED(rv)) {
        inputStream->Close();
        return rv;
      }

      uint32_t count = mCDSOffset - mHeaders[pos + 1]->mOffset;
      uint32_t read = 0;
      char buf[4096];
      while (count > 0) {
        read = std::min(count, (uint32_t)sizeof(buf));

        rv = inputStream->Read(buf, read, &read);
        if (NS_FAILED(rv)) {
          inputStream->Close();
          Cleanup();
          return rv;
        }

        rv = ZW_WriteData(mStream, buf, read);
        if (NS_FAILED(rv)) {
          inputStream->Close();
          Cleanup();
          return rv;
        }

        count -= read;
      }
      inputStream->Close();

      // Rewrite header offsets and update hash
      uint32_t shift = (mHeaders[pos + 1]->mOffset - mHeaders[pos]->mOffset);
      mCDSOffset -= shift;
      int32_t pos2 = pos + 1;
      while (pos2 < mHeaders.Count()) {
        mEntryHash.Put(mHeaders[pos2]->mName, pos2 - 1);
        mHeaders[pos2]->mOffset -= shift;
        pos2++;
      }
    } else {
      // Remove the last entry is just a case of moving the CDS
      mCDSOffset = mHeaders[pos]->mOffset;
      rv = SeekCDS();
      NS_ENSURE_SUCCESS(rv, rv);
    }

    mEntryHash.Remove(mHeaders[pos]->mName);
    mHeaders.RemoveObjectAt(pos);
    mCDSDirty = true;

    return NS_OK;
  }

  return NS_ERROR_FILE_NOT_FOUND;
}

NS_IMETHODIMP nsZipWriter::ProcessQueue(nsIRequestObserver *aObserver,
                                        nsISupports *aContext) {
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;
  if (mInQueue) return NS_ERROR_IN_PROGRESS;

  mProcessObserver = aObserver;
  mProcessContext = aContext;
  mInQueue = true;

  if (mProcessObserver)
    mProcessObserver->OnStartRequest(nullptr);

  BeginProcessingNextItem();

  return NS_OK;
}

NS_IMETHODIMP nsZipWriter::Close() {
  if (!mStream) return NS_ERROR_NOT_INITIALIZED;
  if (mInQueue) return NS_ERROR_IN_PROGRESS;

  if (mCDSDirty) {
    uint32_t size = 0;
    for (int32_t i = 0; i < mHeaders.Count(); i++) {
      nsresult rv = mHeaders[i]->WriteCDSHeader(mStream);
      if (NS_FAILED(rv)) {
        Cleanup();
        return rv;
      }
      size += mHeaders[i]->GetCDSHeaderLength();
    }

    uint8_t buf[ZIP_EOCDR_HEADER_SIZE];
    uint32_t pos = 0;
    WRITE32(buf, &pos, ZIP_EOCDR_HEADER_SIGNATURE);
    WRITE16(buf, &pos, 0);
    WRITE16(buf, &pos, 0);
    WRITE16(buf, &pos, mHeaders.Count());
    WRITE16(buf, &pos, mHeaders.Count());
    WRITE32(buf, &pos, size);
    WRITE32(buf, &pos, mCDSOffset);
    WRITE16(buf, &pos, mComment.Length());

    nsresult rv = ZW_WriteData(mStream, (const char *)buf, pos);
    if (NS_FAILED(rv)) {
      Cleanup();
      return rv;
    }

    rv = ZW_WriteData(mStream, mComment.get(), mComment.Length());
    if (NS_FAILED(rv)) {
      Cleanup();
      return rv;
    }

    nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(mStream);
    rv = seekable->SetEOF();
    if (NS_FAILED(rv)) {
      Cleanup();
      return rv;
    }

    // Go back and rewrite the file headers
    for (int32_t i = 0; i < mHeaders.Count(); i++) {
      nsZipHeader *header = mHeaders[i];
      if (!header->mWriteOnClose) continue;

      rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, header->mOffset);
      if (NS_FAILED(rv)) {
        Cleanup();
        return rv;
      }
      rv = header->WriteFileHeader(mStream);
      if (NS_FAILED(rv)) {
        Cleanup();
        return rv;
      }
    }
  }

  nsresult rv = mStream->Close();
  mStream = nullptr;
  mHeaders.Clear();
  mEntryHash.Clear();
  mQueue.Clear();

  return rv;
}

// Our nsIRequestObserver monitors removal operations performed on the queue
NS_IMETHODIMP nsZipWriter::OnStartRequest(nsIRequest *aRequest) {
  return NS_OK;
}

NS_IMETHODIMP nsZipWriter::OnStopRequest(nsIRequest *aRequest,
                                         nsISupports *aContext,
                                         nsresult aStatusCode) {
  if (NS_FAILED(aStatusCode)) {
    FinishQueue(aStatusCode);
    Cleanup();
  }

  nsresult rv = mStream->Flush();
  if (NS_FAILED(rv)) {
    FinishQueue(rv);
    Cleanup();
    return rv;
  }
  rv = SeekCDS();
  if (NS_FAILED(rv)) {
    FinishQueue(rv);
    return rv;
  }

  BeginProcessingNextItem();

  return NS_OK;
}

/*
 * Make all stored(uncompressed) files align to given alignment size.
 */
NS_IMETHODIMP nsZipWriter::AlignStoredFiles(uint16_t aAlignSize) {
  nsresult rv;

  // Check for range and power of 2.
  if (aAlignSize < 2 || aAlignSize > 32768 ||
      (aAlignSize & (aAlignSize - 1)) != 0) {
    return NS_ERROR_INVALID_ARG;
  }

  for (int i = 0; i < mHeaders.Count(); i++) {
    nsZipHeader *header = mHeaders[i];

    // Check whether this entry is file and compression method is stored.
    bool isdir;
    rv = header->GetIsDirectory(&isdir);
    if (NS_FAILED(rv)) {
      return rv;
    }
    if (isdir || header->mMethod != 0) {
      continue;
    }
    // Pad extra field to align data starting position to specified size.
    uint32_t old_len = header->mLocalFieldLength;
    rv = header->PadExtraField(header->mOffset, aAlignSize);
    if (NS_FAILED(rv)) {
      continue;
    }
    // No padding means data already aligned.
    uint32_t shift = header->mLocalFieldLength - old_len;
    if (shift == 0) {
      continue;
    }

    // Flush any remaining data before we start.
    rv = mStream->Flush();
    if (NS_FAILED(rv)) {
      return rv;
    }

    // Open zip file for reading.
    nsCOMPtr<nsIInputStream> inputStream;
    rv = NS_NewLocalFileInputStream(getter_AddRefs(inputStream), mFile);
    if (NS_FAILED(rv)) {
      return rv;
    }

    nsCOMPtr<nsISeekableStream> in_seekable = do_QueryInterface(inputStream);
    nsCOMPtr<nsISeekableStream> out_seekable = do_QueryInterface(mStream);

    uint32_t data_offset =
        header->mOffset + header->GetFileHeaderLength() - shift;
    uint32_t count = mCDSOffset - data_offset;
    uint32_t read;
    char buf[4096];

    // Shift data to aligned postion.
    while (count > 0) {
      read = std::min(count, (uint32_t)sizeof(buf));

      rv = in_seekable->Seek(nsISeekableStream::NS_SEEK_SET,
                             data_offset + count - read);
      if (NS_FAILED(rv)) {
        break;
      }

      rv = inputStream->Read(buf, read, &read);
      if (NS_FAILED(rv)) {
        break;
      }

      rv = out_seekable->Seek(nsISeekableStream::NS_SEEK_SET,
                              data_offset + count - read + shift);
      if (NS_FAILED(rv)) {
        break;
      }

      rv = ZW_WriteData(mStream, buf, read);
      if (NS_FAILED(rv)) {
        break;
      }

      count -= read;
    }
    inputStream->Close();
    if (NS_FAILED(rv)) {
      Cleanup();
      return rv;
    }

    // Update current header
    rv = out_seekable->Seek(nsISeekableStream::NS_SEEK_SET, header->mOffset);
    if (NS_FAILED(rv)) {
      Cleanup();
      return rv;
    }
    rv = header->WriteFileHeader(mStream);
    if (NS_FAILED(rv)) {
      Cleanup();
      return rv;
    }

    // Update offset of all other headers
    int pos = i + 1;
    while (pos < mHeaders.Count()) {
      mHeaders[pos]->mOffset += shift;
      pos++;
    }
    mCDSOffset += shift;
    rv = SeekCDS();
    if (NS_FAILED(rv)) {
      return rv;
    }
    mCDSDirty = true;
  }

  return NS_OK;
}

nsresult nsZipWriter::InternalAddEntryDirectory(const nsACString &aZipEntry,
                                                PRTime aModTime,
                                                uint32_t aPermissions) {
  RefPtr<nsZipHeader> header = new nsZipHeader();
  NS_ENSURE_TRUE(header, NS_ERROR_OUT_OF_MEMORY);

  uint32_t zipAttributes = ZIP_ATTRS(aPermissions, ZIP_ATTRS_DIRECTORY);

  if (aZipEntry.Last() != '/') {
    nsCString dirPath;
    dirPath.Assign(aZipEntry + NS_LITERAL_CSTRING("/"));
    header->Init(dirPath, aModTime, zipAttributes, mCDSOffset);
  } else
    header->Init(aZipEntry, aModTime, zipAttributes, mCDSOffset);

  if (mEntryHash.Get(header->mName, nullptr))
    return NS_ERROR_FILE_ALREADY_EXISTS;

  nsresult rv = header->WriteFileHeader(mStream);
  if (NS_FAILED(rv)) {
    Cleanup();
    return rv;
  }

  mCDSDirty = true;
  mCDSOffset += header->GetFileHeaderLength();
  mEntryHash.Put(header->mName, mHeaders.Count());

  if (!mHeaders.AppendObject(header)) {
    Cleanup();
    return NS_ERROR_OUT_OF_MEMORY;
  }

  return NS_OK;
}

/*
 * Recovering from an error while adding a new entry is simply a case of
 * seeking back to the CDS. If we fail trying to do that though then cleanup
 * and bail out.
 */
nsresult nsZipWriter::SeekCDS() {
  nsresult rv;
  nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(mStream, &rv);
  if (NS_FAILED(rv)) {
    Cleanup();
    return rv;
  }
  rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, mCDSOffset);
  if (NS_FAILED(rv)) Cleanup();
  return rv;
}

/*
 * In a bad error condition this essentially closes down the component as best
 * it can.
 */
void nsZipWriter::Cleanup() {
  mHeaders.Clear();
  mEntryHash.Clear();
  if (mStream) mStream->Close();
  mStream = nullptr;
  mFile = nullptr;
}

/*
 * Called when writing a file to the zip is complete.
 */
nsresult nsZipWriter::EntryCompleteCallback(nsZipHeader *aHeader,
                                            nsresult aStatus) {
  if (NS_SUCCEEDED(aStatus)) {
    mEntryHash.Put(aHeader->mName, mHeaders.Count());
    if (!mHeaders.AppendObject(aHeader)) {
      mEntryHash.Remove(aHeader->mName);
      SeekCDS();
      return NS_ERROR_OUT_OF_MEMORY;
    }
    mCDSDirty = true;
    mCDSOffset += aHeader->mCSize + aHeader->GetFileHeaderLength();

    if (mInQueue) BeginProcessingNextItem();

    return NS_OK;
  }

  nsresult rv = SeekCDS();
  if (mInQueue) FinishQueue(aStatus);
  return rv;
}

inline nsresult nsZipWriter::BeginProcessingAddition(nsZipQueueItem *aItem,
                                                     bool *complete) {
  if (aItem->mFile) {
    bool exists;
    nsresult rv = aItem->mFile->Exists(&exists);
    NS_ENSURE_SUCCESS(rv, rv);

    if (!exists) return NS_ERROR_FILE_NOT_FOUND;

    bool isdir;
    rv = aItem->mFile->IsDirectory(&isdir);
    NS_ENSURE_SUCCESS(rv, rv);

    rv = aItem->mFile->GetLastModifiedTime(&aItem->mModTime);
    NS_ENSURE_SUCCESS(rv, rv);
    aItem->mModTime *= PR_USEC_PER_MSEC;

    rv = aItem->mFile->GetPermissions(&aItem->mPermissions);
    NS_ENSURE_SUCCESS(rv, rv);

    if (!isdir) {
      // Set up for fall through to stream reader
      rv = NS_NewLocalFileInputStream(getter_AddRefs(aItem->mStream),
                                      aItem->mFile);
      NS_ENSURE_SUCCESS(rv, rv);
    }
    // If a dir then this will fall through to the plain dir addition
  }

  uint32_t zipAttributes = ZIP_ATTRS(aItem->mPermissions, ZIP_ATTRS_FILE);

  if (aItem->mStream || aItem->mChannel) {
    RefPtr<nsZipHeader> header = new nsZipHeader();
    NS_ENSURE_TRUE(header, NS_ERROR_OUT_OF_MEMORY);

    header->Init(aItem->mZipEntry, aItem->mModTime, zipAttributes, mCDSOffset);
    nsresult rv = header->WriteFileHeader(mStream);
    NS_ENSURE_SUCCESS(rv, rv);

    RefPtr<nsZipDataStream> stream = new nsZipDataStream();
    NS_ENSURE_TRUE(stream, NS_ERROR_OUT_OF_MEMORY);
    rv = stream->Init(this, mStream, header, aItem->mCompression);
    NS_ENSURE_SUCCESS(rv, rv);

    if (aItem->mStream) {
      nsCOMPtr<nsIInputStreamPump> pump;
      nsCOMPtr<nsIInputStream> tmpStream = aItem->mStream;
      rv = NS_NewInputStreamPump(getter_AddRefs(pump), tmpStream.forget(), 0, 0,
                                 true);
      NS_ENSURE_SUCCESS(rv, rv);

      rv = pump->AsyncRead(stream, nullptr);
      NS_ENSURE_SUCCESS(rv, rv);
    } else {
      rv = NS_MaybeOpenChannelUsingAsyncOpen(aItem->mChannel, stream);
      NS_ENSURE_SUCCESS(rv, rv);
    }

    return NS_OK;
  }

  // Must be plain directory addition
  *complete = true;
  return InternalAddEntryDirectory(aItem->mZipEntry, aItem->mModTime,
                                   aItem->mPermissions);
}

inline nsresult nsZipWriter::BeginProcessingRemoval(int32_t aPos) {
  // Open the zip file for reading
  nsCOMPtr<nsIInputStream> inputStream;
  nsresult rv = NS_NewLocalFileInputStream(getter_AddRefs(inputStream), mFile);
  NS_ENSURE_SUCCESS(rv, rv);
  nsCOMPtr<nsIInputStreamPump> pump;
  nsCOMPtr<nsIInputStream> tmpStream = inputStream;
  rv = NS_NewInputStreamPump(getter_AddRefs(pump), tmpStream.forget(), 0, 0,
                             true);
  if (NS_FAILED(rv)) {
    inputStream->Close();
    return rv;
  }
  nsCOMPtr<nsIStreamListener> listener;
  rv = NS_NewSimpleStreamListener(getter_AddRefs(listener), mStream, this);
  if (NS_FAILED(rv)) {
    inputStream->Close();
    return rv;
  }

  nsCOMPtr<nsISeekableStream> seekable = do_QueryInterface(mStream);
  rv = seekable->Seek(nsISeekableStream::NS_SEEK_SET, mHeaders[aPos]->mOffset);
  if (NS_FAILED(rv)) {
    inputStream->Close();
    return rv;
  }

  uint32_t shift = (mHeaders[aPos + 1]->mOffset - mHeaders[aPos]->mOffset);
  mCDSOffset -= shift;
  int32_t pos2 = aPos + 1;
  while (pos2 < mHeaders.Count()) {
    mEntryHash.Put(mHeaders[pos2]->mName, pos2 - 1);
    mHeaders[pos2]->mOffset -= shift;
    pos2++;
  }

  mEntryHash.Remove(mHeaders[aPos]->mName);
  mHeaders.RemoveObjectAt(aPos);
  mCDSDirty = true;

  rv = pump->AsyncRead(listener, nullptr);
  if (NS_FAILED(rv)) {
    inputStream->Close();
    Cleanup();
    return rv;
  }
  return NS_OK;
}

/*
 * Starts processing on the next item in the queue.
 */
void nsZipWriter::BeginProcessingNextItem() {
  while (!mQueue.IsEmpty()) {
    nsZipQueueItem next = mQueue[0];
    mQueue.RemoveElementAt(0);

    if (next.mOperation == OPERATION_REMOVE) {
      int32_t pos = -1;
      if (mEntryHash.Get(next.mZipEntry, &pos)) {
        if (pos < mHeaders.Count() - 1) {
          nsresult rv = BeginProcessingRemoval(pos);
          if (NS_FAILED(rv)) FinishQueue(rv);
          return;
        }

        mCDSOffset = mHeaders[pos]->mOffset;
        nsresult rv = SeekCDS();
        if (NS_FAILED(rv)) {
          FinishQueue(rv);
          return;
        }
        mEntryHash.Remove(mHeaders[pos]->mName);
        mHeaders.RemoveObjectAt(pos);
      } else {
        FinishQueue(NS_ERROR_FILE_NOT_FOUND);
        return;
      }
    } else if (next.mOperation == OPERATION_ADD) {
      if (mEntryHash.Get(next.mZipEntry, nullptr)) {
        FinishQueue(NS_ERROR_FILE_ALREADY_EXISTS);
        return;
      }

      bool complete = false;
      nsresult rv = BeginProcessingAddition(&next, &complete);
      if (NS_FAILED(rv)) {
        SeekCDS();
        FinishQueue(rv);
        return;
      }
      if (!complete) return;
    }
  }

  FinishQueue(NS_OK);
}

/*
 * Ends processing with the given status.
 */
void nsZipWriter::FinishQueue(nsresult aStatus) {
  nsCOMPtr<nsIRequestObserver> observer = mProcessObserver;
  nsCOMPtr<nsISupports> context = mProcessContext;
  // Clean up everything first in case the observer decides to queue more
  // things
  mProcessObserver = nullptr;
  mProcessContext = nullptr;
  mInQueue = false;

  if (observer) observer->OnStopRequest(nullptr, context, aStatus);
}