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/*
* Copyright (C) 2007 The Android Open Source Project
*
* 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.
*/
/**
* Byte buffer utilities.
*/
#ifndef __BUFFER_H
#define __BUFFER_H
#ifdef __cplusplus
extern "C" {
#endif
#include <stdlib.h>
/**
* Byte buffer of known size. Keeps track of how much data has been read
* into or written out of the buffer.
*/
typedef struct {
/** Buffered data. */
char* data;
union {
/** For reading. # of bytes we expect. */
size_t expected;
/** For writing. # of bytes to write. */
size_t remaining;
};
/** Actual # of bytes in the buffer. */
size_t size;
/** Amount of memory allocated for this buffer. */
size_t capacity;
} Buffer;
/**
* Returns true if all data has been read into the buffer.
*/
#define bufferReadComplete(buffer) (buffer->expected == buffer->size)
/**
* Returns true if the buffer has been completely written.
*/
#define bufferWriteComplete(buffer) (buffer->remaining == 0)
/**
* Creates a new buffer with the given initial capacity.
*/
Buffer* bufferCreate(size_t initialCapacity);
/**
* Wraps an existing byte array.
*/
Buffer* bufferWrap(char* data, size_t capacity, size_t size);
/**
* Frees and its data.
*/
void bufferFree(Buffer* buffer);
/**
* Prepares buffer to read 'expected' number of bytes. Expands capacity if
* necessary. Returns 0 if successful or -1 if an error occurs allocating
* memory.
*/
int bufferPrepareForRead(Buffer* buffer, size_t expected);
/**
* Reads some data into a buffer. Returns -1 in case of an error and sets
* errno (see read()). Returns 0 for EOF. Updates buffer->size and returns
* the new size after a succesful read.
*
* Precondition: buffer->size < buffer->expected
*/
ssize_t bufferRead(Buffer* buffer, int fd);
/**
* Prepares a buffer to be written out.
*/
void bufferPrepareForWrite(Buffer* buffer);
/**
* Writes data from buffer to the given fd. Returns -1 and sets errno in case
* of an error. Updates buffer->remaining and returns the number of remaining
* bytes to be written after a successful write.
*
* Precondition: buffer->remaining > 0
*/
ssize_t bufferWrite(Buffer* buffer, int fd);
#ifdef __cplusplus
}
#endif
#endif /* __BUFFER_H */
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