gecko-dev/xpcom/io/nsByteBufferInputStream.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.0 (the "NPL"); you may not use this file except in
 * compliance with the NPL.  You may obtain a copy of the NPL at
 * http://www.mozilla.org/NPL/
 *
 * Software distributed under the NPL is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
 * for the specific language governing rights and limitations under the
 * NPL.
 *
 * The Initial Developer of this code under the NPL is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
 * Reserved.
 */

#include "nsIByteBufferInputStream.h"
#include "nsCRT.h"
#include "prcmon.h"

class nsByteBufferInputStream;

////////////////////////////////////////////////////////////////////////////////

class nsByteBufferOutputStream : public nsIByteBufferOutputStream
{
public:
    NS_DECL_ISUPPORTS

    // nsIBaseStream methods:
    NS_IMETHOD Close(void);

    // nsIOutputStream methods:
    NS_IMETHOD Write(const char* aBuf, PRUint32 aCount, PRUint32 *aWriteCount); 

    // nsIByteBufferOutputStream methods:
    NS_IMETHOD Write(nsIInputStream* fromStream, PRUint32 *aWriteCount);

    // nsByteBufferOutputStream methods:
    nsByteBufferOutputStream(nsByteBufferInputStream* in);
    virtual ~nsByteBufferOutputStream();

protected:
    nsByteBufferInputStream*  mInputStream;
};

////////////////////////////////////////////////////////////////////////////////

class nsByteBufferInputStream : public nsIByteBufferInputStream
{
public:
    NS_DECL_ISUPPORTS

    // nsIBaseStream methods:
    NS_IMETHOD Close(void);

    // nsIInputStream methods:
    NS_IMETHOD GetLength(PRUint32 *aLength);
    NS_IMETHOD Read(char* aBuf, PRUint32 aCount, PRUint32 *aReadCount); 

    // nsIByteBufferInputStream methods:
    NS_IMETHOD Fill(nsIInputStream* stream, PRUint32 *aWriteCount);
    NS_IMETHOD Fill(const char* aBuf, PRUint32 aCount, PRUint32 *aWriteCount);

    // nsByteBufferInputStream methods:
    nsByteBufferInputStream(PRBool blocking, PRUint32 size);
    virtual ~nsByteBufferInputStream();

    friend class nsByteBufferOutputStream;

    nsresult Init(void);
    void SetEOF(void);

    PRBool AtEOF() { return mEOF && (mReadCursor == mWriteCursor) && !mFull; }

    PRUint32 ReadableAmount() {
        if (mReadCursor < mWriteCursor) 
            return mWriteCursor - mReadCursor;
        else if (mReadCursor == mWriteCursor && !mFull)
            return 0;
        else
            return (mLength - mReadCursor) + mWriteCursor;
    }

    PRUint32 WritableAmount() {
        if (mWriteCursor < mReadCursor)
            return mWriteCursor - mReadCursor;
        else if (mReadCursor == mWriteCursor && mFull)
            return 0;
        else
            return (mLength - mWriteCursor) + mReadCursor;
    }

    void ReadChunk(char* toBuf, PRUint32 max,
                   PRUint32 end, PRUint32 *totalRef)
    {
        NS_ASSERTION(mReadCursor <= end, "bad range");
        PRUint32 diff = end - mReadCursor;
        PRInt32 amt = PR_MIN(max, diff);
        if (amt > 0) {
            nsCRT::memcpy(toBuf, &mBuffer[mReadCursor], amt);
#ifdef NS_DEBUG
            nsCRT::memset(&mBuffer[mReadCursor], 0xDD, amt);
#endif
            mReadCursor += amt;
            *totalRef += amt;
        }
    }

    nsresult WriteChunk(nsIInputStream* in,
                        PRUint32 end, PRUint32 *totalRef)
    {
        NS_ASSERTION(mWriteCursor <= end, "bad range");
        PRUint32 amt = end - mWriteCursor;
        if (amt > 0) {
            PRUint32 readAmt;
            nsresult rv = in->Read(&mBuffer[mWriteCursor], amt, &readAmt);
            if (NS_FAILED(rv)) return rv;
            mWriteCursor += readAmt;
            *totalRef += readAmt;
        }
        return NS_OK;
    }

protected:
    char*               mBuffer;
    PRUint32            mLength;
    PRUint32            mReadCursor;
    PRUint32            mWriteCursor;
    PRBool              mFull;
    PRBool              mClosed;
    PRBool              mEOF;
    PRBool              mBlocking;
};

////////////////////////////////////////////////////////////////////////////////

class nsDummyBufferStream : public nsIInputStream
{
public:
    NS_DECL_ISUPPORTS

    // nsIBaseStream methods:
    NS_IMETHOD Close(void) {
        NS_NOTREACHED("nsDummyBufferStream::Close");
        return NS_ERROR_FAILURE;
    }

    // nsIInputStream methods:
    NS_IMETHOD GetLength(PRUint32 *aLength) { 
        *aLength = mLength;
        return NS_OK;
    }
    NS_IMETHOD Read(char* aBuf, PRUint32 aCount, PRUint32 *aReadCount) {
        PRUint32 amt = PR_MIN(aCount, mLength);
        if (amt > 0) {
            nsCRT::memcpy(aBuf, mBuffer, amt);
            mBuffer += amt;
            mLength -= amt;
        }
        *aReadCount = amt;
        return NS_OK;
    } 

    // nsDummyBufferStream methods:
    nsDummyBufferStream(const char* buffer, PRUint32 length)
        : mBuffer(buffer), mLength(length) {}
    ~nsDummyBufferStream() {}

protected:
    const char* mBuffer;
    PRUint32    mLength;
};

NS_IMETHODIMP
nsDummyBufferStream::QueryInterface(REFNSIID aIID, void** aInstancePtr)
{
    NS_NOTREACHED("nsDummyBufferStream::QueryInterface");
    return NS_ERROR_FAILURE;
}

NS_IMETHODIMP_(nsrefcnt)
nsDummyBufferStream::AddRef(void)
{
    NS_NOTREACHED("nsDummyBufferStream::AddRef");
    return 1;
}

NS_IMETHODIMP_(nsrefcnt)
nsDummyBufferStream::Release(void)
{
    NS_NOTREACHED("nsDummyBufferStream::Release");
    return 1;
}

////////////////////////////////////////////////////////////////////////////////
// nsByteBufferInputStream methods:
////////////////////////////////////////////////////////////////////////////////

nsByteBufferInputStream::nsByteBufferInputStream(PRBool blocking, PRUint32 size)
    : mBuffer(nsnull), mLength(size), mReadCursor(0), mWriteCursor(0), 
      mFull(PR_FALSE), mClosed(PR_FALSE), mEOF(PR_FALSE), mBlocking(blocking)
{
    NS_INIT_REFCNT();
}

nsresult
nsByteBufferInputStream::Init(void)
{
    mBuffer = new char[mLength];
    if (mBuffer == nsnull)
        return NS_ERROR_OUT_OF_MEMORY;
    return NS_OK;
}

nsByteBufferInputStream::~nsByteBufferInputStream()
{
    (void)Close();
    if (mBuffer) delete mBuffer;
}

NS_IMPL_ADDREF(nsByteBufferInputStream);
NS_IMPL_RELEASE(nsByteBufferInputStream);

NS_IMETHODIMP
nsByteBufferInputStream::QueryInterface(REFNSIID aIID, void** aInstancePtr)
{
    if (aInstancePtr == nsnull)
        return NS_ERROR_NULL_POINTER;
    if (aIID.Equals(nsIByteBufferInputStream::GetIID()) ||
        aIID.Equals(nsIInputStream::GetIID()) ||
        aIID.Equals(nsIBaseStream::GetIID()) ||
        aIID.Equals(nsISupports::GetIID())) {
        *aInstancePtr = this;
        NS_ADDREF_THIS();
        return NS_OK;
    }
    return NS_NOINTERFACE;
}

NS_IMETHODIMP
nsByteBufferInputStream::Close(void)
{
    if (mBlocking) 
        PR_CEnterMonitor(this);
    mClosed = PR_TRUE;
    if (mBlocking) {
        PR_CNotify(this);   // wake up the writer
        PR_CExitMonitor(this);
    }
    return NS_OK;
}

NS_IMETHODIMP
nsByteBufferInputStream::GetLength(PRUint32 *aLength)
{
    if (mClosed)
        return NS_BASE_STREAM_CLOSED;

    if (mBlocking) 
        PR_CEnterMonitor(this);
    *aLength = ReadableAmount();
    if (mBlocking) 
        PR_CExitMonitor(this);
    return NS_OK;
}

NS_IMETHODIMP
nsByteBufferInputStream::Read(char* aBuf, PRUint32 aCount, PRUint32 *aReadCount)
{
    nsresult rv = NS_OK;
    if (mClosed)
        return NS_BASE_STREAM_CLOSED;

    if (AtEOF())
        return NS_BASE_STREAM_EOF;

    if (mBlocking) 
        PR_CEnterMonitor(this);
    *aReadCount = 0;

    /*while (aCount > 0)*/ {   // XXX should this block trying to fill the buffer, or return ASAP?
        if (ReadableAmount() == 0) {
            if (mBlocking) {
                PRStatus status = PR_CWait(this, PR_INTERVAL_NO_TIMEOUT);
                if (status != PR_SUCCESS) {
                    rv = NS_ERROR_FAILURE;
                    goto done;
                }
            }
            if (mEOF) {
                rv = NS_BASE_STREAM_EOF;
                goto done;
            }
            else if (!mBlocking) {
                rv = NS_BASE_STREAM_WOULD_BLOCK;
                goto done;
            }
        }

        // wrap-around buffer:
        PRUint32 amt = 0;
        if (mReadCursor >= mWriteCursor || mFull) {
            ReadChunk(aBuf, aCount, mLength, &amt);
            *aReadCount += amt;
            aBuf += amt;
            aCount -= amt;
            if (mReadCursor == mLength) {
                mReadCursor = 0;
                amt = 0;
                ReadChunk(aBuf, aCount, mWriteCursor, &amt);
                *aReadCount += amt;
                aBuf += amt;
                aCount -= amt;
            }
        }
        else {
            ReadChunk(aBuf, aCount, mWriteCursor, &amt);
            *aReadCount += amt;
            aBuf += amt;
            aCount -= amt;
        }
        if (*aReadCount)
            mFull = PR_FALSE;

        if (mBlocking) 
            PR_CNotify(this);   // tell the writer there's space
    }
  done:
    if (mBlocking) 
        PR_CExitMonitor(this);
    return rv;
}

NS_IMETHODIMP
nsByteBufferInputStream::Fill(const char* aBuf, PRUint32 aCount, PRUint32 *aWriteCount)
{
    nsDummyBufferStream in(aBuf, aCount);
    return Fill(&in, aWriteCount);
}

NS_IMETHODIMP
nsByteBufferInputStream::Fill(nsIInputStream* stream, PRUint32 *aWriteCount)
{
    nsresult rv = NS_OK;

    if (mClosed || mEOF)
        return NS_BASE_STREAM_CLOSED;

    *aWriteCount = 0;
    PRUint32 aCount;
    rv = stream->GetLength(&aCount);
    if (NS_FAILED(rv)) return rv;

    if (mBlocking) 
        PR_CEnterMonitor(this);

    while (aCount > 0) {
        if (WritableAmount() == 0) {
            if (mBlocking) {
                PRStatus status = PR_CWait(this, PR_INTERVAL_NO_TIMEOUT);
                if (status != PR_SUCCESS) {
                    rv = NS_ERROR_FAILURE;
                    goto done;
                }
            }
            if (mClosed) {
                rv = NS_BASE_STREAM_CLOSED;
                goto done;
            }
            else if (!mBlocking) {
                rv = NS_BASE_STREAM_WOULD_BLOCK;
                goto done;
            }
        }

        // wrap-around buffer:
        PRUint32 amt = 0;
        if (mReadCursor <= mWriteCursor && !mFull) {
            rv = WriteChunk(stream, mLength, &amt);
            if (NS_FAILED(rv)) goto done;
            *aWriteCount += amt;
            aCount -= amt;
            if (mWriteCursor == mLength) {
                mWriteCursor = 0;
                amt = 0;
                rv = WriteChunk(stream, mReadCursor, &amt);
                if (NS_FAILED(rv)) goto done;
                *aWriteCount += amt;
                aCount -= amt;
            }
        }
        else {
            rv = WriteChunk(stream, mReadCursor, &amt);
            if (NS_FAILED(rv)) goto done;
            *aWriteCount += amt;
            aCount -= amt;
        }
        if (mWriteCursor == mReadCursor)
            mFull = PR_TRUE;

        if (mBlocking) 
            PR_CNotify(this);   // tell the reader there's more
    }
  done:
    if (mBlocking) 
        PR_CExitMonitor(this);
    return rv;
}

void
nsByteBufferInputStream::SetEOF()
{
    if (mBlocking) 
        PR_CEnterMonitor(this);
    mEOF = PR_TRUE;
    if (mBlocking) {
        PR_CNotify(this);   // wake up the reader
        PR_CExitMonitor(this);
    }
}

////////////////////////////////////////////////////////////////////////////////
// nsByteBufferOutputStream methods:
////////////////////////////////////////////////////////////////////////////////

nsByteBufferOutputStream::nsByteBufferOutputStream(nsByteBufferInputStream* in)
    : mInputStream(in)
{
    NS_INIT_REFCNT();
    NS_ADDREF(mInputStream);
}

nsByteBufferOutputStream::~nsByteBufferOutputStream()
{
    (void)Close();
    NS_IF_RELEASE(mInputStream);
}

NS_IMPL_ADDREF(nsByteBufferOutputStream);
NS_IMPL_RELEASE(nsByteBufferOutputStream);

NS_IMETHODIMP
nsByteBufferOutputStream::QueryInterface(REFNSIID aIID, void** aInstancePtr)
{
    if (aInstancePtr == nsnull)
        return NS_ERROR_NULL_POINTER;
    if (aIID.Equals(nsIByteBufferOutputStream::GetIID()) ||
        aIID.Equals(nsIOutputStream::GetIID()) ||
        aIID.Equals(nsIBaseStream::GetIID()) ||
        aIID.Equals(nsISupports::GetIID())) {
        *aInstancePtr = this;
        NS_ADDREF_THIS();
        return NS_OK;
    }
    return NS_NOINTERFACE;
}

NS_IMETHODIMP
nsByteBufferOutputStream::Close(void)
{
    mInputStream->SetEOF();
    return NS_OK;
}

NS_IMETHODIMP
nsByteBufferOutputStream::Write(const char* aBuf, PRUint32 aCount, PRUint32 *aWriteCount)
{
    return mInputStream->Fill(aBuf, aCount, aWriteCount);
}

NS_IMETHODIMP
nsByteBufferOutputStream::Write(nsIInputStream* fromStream, PRUint32 *aWriteCount)
{
    return mInputStream->Fill(fromStream, aWriteCount);
}

////////////////////////////////////////////////////////////////////////////////

NS_BASE nsresult
NS_NewByteBufferInputStream(nsIByteBufferInputStream* *result,
                            PRBool blocking, PRUint32 size)
{
    nsresult rv;
    nsByteBufferInputStream* inStr = nsnull;

    inStr = new nsByteBufferInputStream(blocking, size);
    if (inStr == nsnull)
        return NS_ERROR_OUT_OF_MEMORY;
    rv = inStr->Init();
    if (NS_FAILED(rv)) {
        delete inStr;
        return rv;
    }
    NS_ADDREF(inStr);
    *result = inStr;
    return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////

NS_BASE nsresult
NS_NewPipe(nsIInputStream* *inStrResult,
           nsIOutputStream* *outStrResult,
           PRBool blocking, PRUint32 size)
{
    nsresult rv;
    nsIByteBufferInputStream* in;
    nsByteBufferInputStream* inStr;
    nsByteBufferOutputStream* outStr;

    rv = NS_NewByteBufferInputStream(&in, blocking, size);
    if (NS_FAILED(rv)) return rv;
    // this cast is safe, because we know how NS_NewByteBufferInputStream works:
    inStr = NS_STATIC_CAST(nsByteBufferInputStream*, in);
    
    outStr = new nsByteBufferOutputStream(inStr);
    if (outStr == nsnull) {
        NS_RELEASE(inStr);
        return NS_ERROR_OUT_OF_MEMORY;
    }
    NS_ADDREF(outStr);

    *inStrResult = inStr;
    *outStrResult = outStr;
    return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////