gecko-dev/mailnews/base/util/nsMsgLineBuffer.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * 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) 1999 Netscape Communications Corporation.  All Rights
 * Reserved.
 */

#include "msgCore.h"
#include "nsMsgLineBuffer.h"

#include "nsIInputStream.h" // used by nsMsgLineStreamBuffer

nsByteArray::nsByteArray()
{
	m_buffer = NULL;
	m_bufferSize = 0;
	m_bufferPos = 0;
}

nsByteArray::~nsByteArray()
{
	PR_FREEIF(m_buffer);
}

nsresult nsByteArray::GrowBuffer(PRUint32 desired_size, PRUint32 quantum)
{
	if (m_bufferSize < desired_size)
	{
		char *new_buf;
		PRUint32 increment = desired_size - m_bufferSize;
		if (increment < quantum) /* always grow by a minimum of N bytes */
			increment = quantum;


		new_buf = (m_buffer
				 ? (char *) PR_REALLOC (m_buffer, (m_bufferSize + increment))
				 : (char *) PR_MALLOC (m_bufferSize + increment));
		if (! new_buf)
			return NS_ERROR_OUT_OF_MEMORY;
		m_buffer = new_buf;
		m_bufferSize += increment;
	}
  return 0;
}

nsresult nsByteArray::AppendString(const char *string)
{
	PRUint32 strLength = (string) ? PL_strlen(string) : 0;
	return AppendBuffer(string, strLength);

}

nsresult nsByteArray::AppendBuffer(const char *buffer, PRUint32 length)
{
	nsresult ret = NS_OK;
	if (m_bufferPos + length > m_bufferSize)
		ret = GrowBuffer(m_bufferPos + length, 1024);
	if (ret == NS_OK)
	{
		memcpy(m_buffer + m_bufferPos, buffer, length);
		m_bufferPos += length;
	}
	return ret;
}

nsMsgLineBuffer::nsMsgLineBuffer(nsMsgLineBufferHandler *handler, PRBool convertNewlinesP)
{
	m_handler = handler;
	m_convertNewlinesP = convertNewlinesP;
}

nsMsgLineBuffer::~nsMsgLineBuffer()
{
}

PRInt32	nsMsgLineBuffer::BufferInput(const char *net_buffer, PRInt32 net_buffer_size)
{
    int status = 0;
    if (m_bufferPos > 0 && m_buffer && m_buffer[m_bufferPos - 1] == CR &&
        net_buffer_size > 0 && net_buffer[0] != LF) {
        /* The last buffer ended with a CR.  The new buffer does not start
           with a LF.  This old buffer should be shipped out and discarded. */
        PR_ASSERT(m_bufferSize > m_bufferPos);
        if (m_bufferSize <= m_bufferPos) return -1;
        status = ConvertAndSendBuffer();
        if (status < 0) 
			return status;
        m_bufferPos = 0;
    }
    while (net_buffer_size > 0)
	{
        const char *net_buffer_end = net_buffer + net_buffer_size;
        const char *newline = 0;
        const char *s;
        
        
        for (s = net_buffer; s < net_buffer_end; s++)
		{
            /* Move forward in the buffer until the first newline.
               Stop when we see CRLF, CR, or LF, or the end of the buffer.
               *But*, if we see a lone CR at the *very end* of the buffer,
               treat this as if we had reached the end of the buffer without
               seeing a line terminator.  This is to catch the case of the
               buffers splitting a CRLF pair, as in "FOO\r\nBAR\r" "\nBAZ\r\n".
		   */
            if (*s == CR || *s == LF)
			{
                newline = s;
                if (newline[0] == CR)
				{
                    if (s == net_buffer_end - 1)
					{
                        /* CR at end - wait for the next character. */
                        newline = 0;
                        break;
					}
                    else if (newline[1] == LF)
                        /* CRLF seen; swallow both. */
                        newline++;
				}
                newline++;
				break;
			}
		}
        
        /* Ensure room in the net_buffer and append some or all of the current
           chunk of data to it. */
        {
            const char *end = (newline ? newline : net_buffer_end);
            PRUint32 desired_size = (end - net_buffer) + m_bufferPos + 1;
            
            if (desired_size >= m_bufferSize)
            {
                status = GrowBuffer (desired_size, 1024);
                if (status < 0) 
					return status;
            }
            memcpy (m_buffer + m_bufferPos, net_buffer, (end - net_buffer));
            m_bufferPos += (end - net_buffer);
        }
        
        /* Now m_buffer contains either a complete line, or as complete
           a line as we have read so far.
           
           If we have a line, process it, and then remove it from `m_buffer'.
           Then go around the loop again, until we drain the incoming data.
           */
        if (!newline)
            return 0;
        
        status = ConvertAndSendBuffer();
        if (status < 0) return status;
        
        net_buffer_size -= (newline - net_buffer);
        net_buffer = newline;
        m_bufferPos = 0;
	}
#ifdef DEBUG_bienvenu
	printf("returning from buffer input m_bufferPos = %ld\n", m_bufferPos);
#endif	
    return 0;
}

PRInt32 nsMsgLineBuffer::HandleLine(char *line, PRUint32 line_length)
{
	NS_ASSERTION(FALSE, "must override this method if you don't provide a handler");
	return 0;
}

PRInt32 nsMsgLineBuffer::ConvertAndSendBuffer()
{
    /* Convert the line terminator to the native form.
     */

	char *buf = m_buffer;
	PRInt32 length = m_bufferPos;

    char* newline;
    
    PR_ASSERT(buf && length > 0);
    if (!buf || length <= 0) 
		return -1;
    newline = buf + length;
    
    PR_ASSERT(newline[-1] == CR || newline[-1] == LF);
    if (newline[-1] != CR && newline[-1] != LF)
		return -1;
    
    if (!m_convertNewlinesP)
	{
	}
#if (MSG_LINEBREAK_LEN == 1)
    else if ((newline - buf) >= 2 &&
             newline[-2] == CR &&
             newline[-1] == LF)
	{
        /* CRLF -> CR or LF */
        buf [length - 2] = MSG_LINEBREAK[0];
        length--;
	}
    else if (newline > buf + 1 &&
             newline[-1] != MSG_LINEBREAK[0])
	{
        /* CR -> LF or LF -> CR */
        buf [length - 1] = MSG_LINEBREAK[0];
	}
#else
    else if (((newline - buf) >= 2 && newline[-2] != CR) ||
             ((newline - buf) >= 1 && newline[-1] != LF))
	{
        /* LF -> CRLF or CR -> CRLF */
        length++;
        buf[length - 2] = MSG_LINEBREAK[0];
        buf[length - 1] = MSG_LINEBREAK[1];
	}
#endif
    
    return (m_handler) ? m_handler->HandleLine(buf, length) : HandleLine(buf, length);
}

// If there's still some data (non CRLF terminated) flush it out
PRInt32 nsMsgLineBuffer::FlushLastLine()
{
	char *buf = m_buffer + m_bufferPos;
	PRInt32 length = m_bufferPos - 1;
	if (length > 0)
		return (m_handler) ? m_handler->HandleLine(buf, length) : HandleLine(buf, length);
	else
		return 0;
}

///////////////////////////////////////////////////////////////////////////////////////////////////
// This is a utility class used to efficiently extract lines from an input stream by buffering
// read but unprocessed stream data in a buffer. 
///////////////////////////////////////////////////////////////////////////////////////////////////

nsMsgLineStreamBuffer::nsMsgLineStreamBuffer(PRUint32 aBufferSize, const char * aEndOfLineToken, 
											 PRBool aAllocateNewLines, PRBool aEatCRLFs) 
											: m_eatCRLFs(aEatCRLFs), m_allocateNewLines(aAllocateNewLines),
											  m_endOfLineToken(aEndOfLineToken)
{
	NS_PRECONDITION(aBufferSize > 0, "invalid buffer size!!!");
	m_dataBuffer = nsnull;
	m_startPos = nsnull;

	// used to buffer incoming data by ReadNextLineFromInput
	if (aBufferSize > 0)
	{
		m_dataBuffer = (char *) PR_CALLOC(sizeof(char) * aBufferSize);
		m_startPos = m_dataBuffer;
	}

	m_dataBufferSize = aBufferSize;
}

nsMsgLineStreamBuffer::~nsMsgLineStreamBuffer()
{
	PR_FREEIF(m_dataBuffer); // release our buffer...
}

// the design for this method has an inherit bug: if the length of the line is greater than the size of m_dataBufferSize, 
// then we'll never find the next line because we can't hold the whole line in memory. 
// aInputStream - the input stream we want to read a line from
// aPauseForMoreData is returned as PR_TRUE if the stream does not yet contain a line and we must wait for more
// data to come into the stream.

// Note to people wishing to modify this function: Be *VERY CAREFUL* this is a critical function used by all of
// our mail protocols including imap, nntp, and pop. If you screw it up, you could break a lot of stuff.....

char * nsMsgLineStreamBuffer::ReadNextLine(nsIInputStream * aInputStream, PRUint32 &aNumBytesInLine, PRBool &aPauseForMoreData)
{
	// try to extract a line from m_inputBuffer. If we don't have an entire line, 
	// then read more bytes out from the stream. If the stream is empty then wait
	// on the monitor for more data to come in.

	NS_PRECONDITION(m_startPos && m_dataBufferSize > 0, "invalid input arguments for read next line from input");
	
	// initialize out values
	aPauseForMoreData = PR_FALSE;
	aNumBytesInLine = 0;
	char * endOfLine = nsnull;

	PRUint32 numBytesInBuffer = PL_strlen(m_startPos);
	
	if (numBytesInBuffer > 0) // any data in our internal buffer?
		endOfLine = PL_strstr(m_startPos, m_endOfLineToken); // see if we already have a line ending...

	// it's possible that we got here before the first time we receive data from the server
	// so aInputStream will be nsnull...
	if (!endOfLine && aInputStream) // get some more data from the server
	{
		PRUint32 numBytesInStream = 0;
		PRUint32 numBytesCopied = 0;
		aInputStream->GetLength(&numBytesInStream);
		// if the number of bytes we want to read from the stream, is greater than the number
		// of bytes left in our buffer, then we need to shift the start pos and its contents
		// down to the beginning of m_dataBuffer...
		PRUint32 numFreeBytesInBuffer = (m_dataBuffer + m_dataBufferSize) - (m_startPos + numBytesInBuffer);
		if (numBytesInStream > numFreeBytesInBuffer)
		{
			nsCRT::memcpy(m_dataBuffer, m_startPos, numBytesInBuffer);
			m_dataBuffer[numBytesInBuffer] = '\0'; // make sure the end of the buffer is terminated
			m_startPos = m_dataBuffer; // update the new start position
			// update the number of free bytes in the buffer
			numFreeBytesInBuffer = m_dataBufferSize - numBytesInBuffer;
		}

		PRUint32 numBytesToCopy = PR_MIN(numFreeBytesInBuffer - 1 /* leave one for a null terminator */, numBytesInStream);
		// read the data into the end of our data buffer
		if (numBytesToCopy > 0)
		{
			aInputStream->Read(m_startPos + numBytesInBuffer, numBytesToCopy, &numBytesCopied);
			m_startPos[numBytesInBuffer + numBytesCopied] = '\0';
		}

		// okay, now that we've tried to read in more data from the stream, look for another end of line 
		// character 
		endOfLine = PL_strstr(m_startPos, m_endOfLineToken);

	}

	// okay, now check again for endOfLine.
	if (endOfLine)
	{
		if (!m_eatCRLFs)
			endOfLine += PL_strlen(m_endOfLineToken); // count for CRLF

		// PR_CALLOC zeros out the allocated line
		char* newLine = (char*) PR_CALLOC(endOfLine-m_startPos+1);
		if (!newLine)
			return nsnull;

		nsCRT::memcpy(newLine, m_startPos, endOfLine-m_startPos); // copy the string into the new line buffer
		aNumBytesInLine = endOfLine - m_startPos;

		if (m_eatCRLFs)
			endOfLine += PL_strlen(m_endOfLineToken); // advance past CRLF if we haven't already done so...

		// now we need to update the data buffer to go past the line we just read out. 
		if (PL_strlen(endOfLine) <= 0) // if no more data in the buffer, then just zero out the buffer...
			m_startPos[0] = '\0';
		else  // advance 
			m_startPos = endOfLine; // move us up to the end of the line
		return newLine;
	}

	aPauseForMoreData = PR_TRUE;
	return nsnull; // if we somehow got here. we don't have another line in the buffer yet...need to wait for more data...
}