gecko-dev/netwerk/base/nsTemporaryFileInputStream.cpp

106 строки
3.3 KiB
C++

/* -*- 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 "nsTemporaryFileInputStream.h"
#include "nsStreamUtils.h"
#include <algorithm>
NS_IMPL_ISUPPORTS(nsTemporaryFileInputStream, nsIInputStream)
nsTemporaryFileInputStream::nsTemporaryFileInputStream(FileDescOwner* aFileDescOwner, uint64_t aStartPos, uint64_t aEndPos)
: mFileDescOwner(aFileDescOwner),
mStartPos(aStartPos),
mEndPos(aEndPos),
mClosed(false)
{
NS_ASSERTION(aStartPos <= aEndPos, "StartPos should less equal than EndPos!");
}
NS_IMETHODIMP
nsTemporaryFileInputStream::Close()
{
mClosed = true;
return NS_OK;
}
NS_IMETHODIMP
nsTemporaryFileInputStream::Available(uint64_t * bytesAvailable)
{
if (mClosed)
return NS_BASE_STREAM_CLOSED;
NS_ASSERTION(mStartPos <= mEndPos, "StartPos should less equal than EndPos!");
*bytesAvailable = mEndPos - mStartPos;
return NS_OK;
}
NS_IMETHODIMP
nsTemporaryFileInputStream::Read(char* buffer, uint32_t count, uint32_t* bytesRead)
{
return ReadSegments(NS_CopySegmentToBuffer, buffer, count, bytesRead);
}
NS_IMETHODIMP
nsTemporaryFileInputStream::ReadSegments(nsWriteSegmentFun writer,
void * closure,
uint32_t count,
uint32_t * result)
{
NS_ASSERTION(result, "null ptr");
NS_ASSERTION(mStartPos <= mEndPos, "bad stream state");
*result = 0;
if (mClosed) {
return NS_BASE_STREAM_CLOSED;
}
mozilla::MutexAutoLock lock(mFileDescOwner->FileMutex());
PR_Seek64(mFileDescOwner->mFD, mStartPos, PR_SEEK_SET);
// Limit requested count to the amount remaining in our section of the file.
count = std::min(count, uint32_t(mEndPos - mStartPos));
char buf[4096];
while (*result < count) {
uint32_t bufCount = std::min(count - *result, (uint32_t) sizeof(buf));
int32_t bytesRead = PR_Read(mFileDescOwner->mFD, buf, bufCount);
if (bytesRead < 0) {
return NS_ErrorAccordingToNSPR();
}
int32_t bytesWritten = 0;
while (bytesWritten < bytesRead) {
uint32_t writerCount = 0;
nsresult rv = writer(this, closure, buf + bytesWritten, *result,
bytesRead - bytesWritten, &writerCount);
if (NS_FAILED(rv) || writerCount == 0) {
// nsIInputStream::ReadSegments' contract specifies that errors
// from writer are not propagated to ReadSegments' caller.
//
// If writer fails, leaving bytes still in buf, that's okay: we
// only update mStartPos to reflect successful writes, so the call
// to PR_Seek64 at the top will restart us at the right spot.
return NS_OK;
}
NS_ASSERTION(writerCount <= (uint32_t) (bytesRead - bytesWritten),
"writer should not write more than we asked it to write");
bytesWritten += writerCount;
*result += writerCount;
mStartPos += writerCount;
}
}
return NS_OK;
}
NS_IMETHODIMP
nsTemporaryFileInputStream::IsNonBlocking(bool * nonBlocking)
{
*nonBlocking = false;
return NS_OK;
}