gecko-dev/netwerk/base/ArrayBufferInputStream.cpp

134 строки
3.7 KiB
C++

/* -*- Mode: C++; tab-width: 4; 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 <algorithm>
#include "ArrayBufferInputStream.h"
#include "nsStreamUtils.h"
#include "jsapi.h"
#include "jsfriendapi.h"
NS_IMPL_ISUPPORTS(ArrayBufferInputStream, nsIArrayBufferInputStream, nsIInputStream);
ArrayBufferInputStream::ArrayBufferInputStream()
: mBufferLength(0)
, mOffset(0)
, mPos(0)
, mClosed(false)
{
}
NS_IMETHODIMP
ArrayBufferInputStream::SetData(JS::Handle<JS::Value> aBuffer,
uint32_t aByteOffset,
uint32_t aLength,
JSContext* aCx)
{
if (!aBuffer.isObject()) {
return NS_ERROR_FAILURE;
}
JS::RootedObject arrayBuffer(aCx, &aBuffer.toObject());
if (!JS_IsArrayBufferObject(arrayBuffer)) {
return NS_ERROR_FAILURE;
}
mArrayBuffer.emplace(aCx, arrayBuffer);
uint32_t buflen = JS_GetArrayBufferByteLength(arrayBuffer);
mOffset = std::min(buflen, aByteOffset);
mBufferLength = std::min(buflen - mOffset, aLength);
return NS_OK;
}
NS_IMETHODIMP
ArrayBufferInputStream::Close()
{
mClosed = true;
return NS_OK;
}
NS_IMETHODIMP
ArrayBufferInputStream::Available(uint64_t* aCount)
{
if (mClosed) {
return NS_BASE_STREAM_CLOSED;
}
if (mArrayBuffer) {
uint32_t buflen = JS_GetArrayBufferByteLength(mArrayBuffer->get());
*aCount = buflen ? buflen - mPos : 0;
} else {
*aCount = 0;
}
return NS_OK;
}
NS_IMETHODIMP
ArrayBufferInputStream::Read(char* aBuf, uint32_t aCount, uint32_t *aReadCount)
{
return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, aReadCount);
}
NS_IMETHODIMP
ArrayBufferInputStream::ReadSegments(nsWriteSegmentFun writer, void *closure,
uint32_t aCount, uint32_t *result)
{
NS_ASSERTION(result, "null ptr");
NS_ASSERTION(mBufferLength >= mPos, "bad stream state");
if (mClosed) {
return NS_BASE_STREAM_CLOSED;
}
MOZ_ASSERT(mArrayBuffer || (mPos == mBufferLength), "stream inited incorrectly");
*result = 0;
while (mPos < mBufferLength) {
uint32_t remaining = mBufferLength - mPos;
MOZ_ASSERT(mArrayBuffer);
uint32_t byteLength = JS_GetArrayBufferByteLength(mArrayBuffer->get());
if (byteLength == 0) {
mClosed = true;
return NS_BASE_STREAM_CLOSED;
}
char buffer[8192];
uint32_t count = std::min(std::min(aCount, remaining), uint32_t(mozilla::ArrayLength(buffer)));
if (count == 0) {
break;
}
// It is just barely possible that writer() will detach the ArrayBuffer's
// data, setting its length to zero. Or move the data to a different memory
// area. (This would only happen in a subclass that passed something other
// than NS_CopySegmentToBuffer as 'writer'). So copy the data out into a
// holding area before passing it to writer().
{
JS::AutoCheckCannotGC nogc;
char* src = (char*) JS_GetArrayBufferData(mArrayBuffer->get(), nogc) + mOffset + mPos;
memcpy(buffer, src, count);
}
uint32_t written;
nsresult rv = writer(this, closure, buffer, 0, count, &written);
if (NS_FAILED(rv)) {
// InputStreams do not propagate errors to caller.
return NS_OK;
}
NS_ASSERTION(written <= count,
"writer should not write more than we asked it to write");
mPos += written;
*result += written;
aCount -= written;
}
return NS_OK;
}
NS_IMETHODIMP
ArrayBufferInputStream::IsNonBlocking(bool *aNonBlocking)
{
*aNonBlocking = true;
return NS_OK;
}