FreeRDP/libfreerdp-utils/stream.c
2012-05-11 16:52:02 +02:00

113 lines
3.6 KiB
C

/*
* FreeRDP: A Remote Desktop Protocol Client
* Stream Utils
*
* Copyright 2011 Vic Lee
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <freerdp/utils/memory.h>
#include <freerdp/utils/stream.h>
/**
* Allocates and initializes a STREAM structure.
* STREAM are used to ease data access in read and write operations.
* They consist of a buffer containing the data we want to access, and an offset associated to it, and keeping
* track of the 'current' position in the stream. A list of functions can then be used to read/write different
* type of data to/from it.
* @see stream.h for the list of data access functions.
*
* @param size [in] - size of the buffer that will ba allocated to the stream.
* If 0, there will be no buffer attached to the stream. The caller
* then needs to call stream_attach() to link an existing buffer to this stream.
* Caution: calling stream_attach() on a stream with an existing buffer will result
* in this buffer being lost, and possible memory leak.
*
* @return A pointer to an allocated and initialized STREAM structure.
* This pointer need to be deallocated using the stream_free() function.
*/
STREAM* stream_new(int size)
{
STREAM* stream;
stream = xnew(STREAM);
if (stream != NULL)
{
if (size != 0)
{
size = size > 0 ? size : 0x400;
stream->data = (uint8*) xzalloc(size);
stream->p = stream->data;
stream->size = size;
}
}
return stream;
}
/**
* This function is used to deallocate a stream that was allocated using stream_new().
* Caution: the buffer linked to the stream will be deallocated in the process. If this buffer was attached
* using the stream_attach() function, the stream_detach() function needs to be called before calling stream_free()
* otherwise it will be freed in the process.
*
* @param stream [in] - Pointer to the STREAM structure that needs to be deallocated.
* This pointer is invalid on return.
*/
void stream_free(STREAM* stream)
{
if (stream != NULL)
{
if (stream->data != NULL)
xfree(stream->data);
xfree(stream);
}
}
/**
* This function is used to extend the size of an existing stream.
* It will infact extend the attached buffer, fill the newly allocated region with 0, and reset the current
* stream position.
* If the stream did not have a buffer attached, a new one will be allocated and attached.
*
* @param stream [in/out] pointer to the STREAM structure that needs to be extended.
* @param request_size [in] Number of bytes to add to the existing stream.
* If the value is < the existing size, then the existing size is doubled.
*/
void stream_extend(STREAM* stream, int request_size)
{
int pos;
int original_size;
int increased_size;
pos = stream_get_pos(stream);
original_size = stream->size;
increased_size = (request_size > original_size ? request_size : original_size);
stream->size += increased_size;
if (original_size == 0)
stream->data = (uint8*) xmalloc(stream->size);
else
stream->data = (uint8*) xrealloc(stream->data, stream->size);
memset(stream->data + original_size, 0, increased_size);
stream_set_pos(stream, pos);
}