112 lines
2.7 KiB
C
112 lines
2.7 KiB
C
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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* Byte buffer utilities.
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*/
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#ifndef __BUFFER_H
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#define __BUFFER_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <stdlib.h>
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/**
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* Byte buffer of known size. Keeps track of how much data has been read
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* into or written out of the buffer.
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*/
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typedef struct {
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/** Buffered data. */
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char* data;
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union {
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/** For reading. # of bytes we expect. */
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size_t expected;
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/** For writing. # of bytes to write. */
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size_t remaining;
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};
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/** Actual # of bytes in the buffer. */
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size_t size;
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/** Amount of memory allocated for this buffer. */
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size_t capacity;
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} Buffer;
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/**
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* Returns true if all data has been read into the buffer.
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*/
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#define bufferReadComplete(buffer) (buffer->expected == buffer->size)
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/**
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* Returns true if the buffer has been completely written.
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*/
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#define bufferWriteComplete(buffer) (buffer->remaining == 0)
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/**
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* Creates a new buffer with the given initial capacity.
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*/
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Buffer* bufferCreate(size_t initialCapacity);
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/**
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* Wraps an existing byte array.
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*/
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Buffer* bufferWrap(char* data, size_t capacity, size_t size);
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/**
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* Frees and its data.
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*/
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void bufferFree(Buffer* buffer);
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/**
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* Prepares buffer to read 'expected' number of bytes. Expands capacity if
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* necessary. Returns 0 if successful or -1 if an error occurs allocating
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* memory.
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*/
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int bufferPrepareForRead(Buffer* buffer, size_t expected);
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/**
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* Reads some data into a buffer. Returns -1 in case of an error and sets
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* errno (see read()). Returns 0 for EOF. Updates buffer->size and returns
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* the new size after a succesful read.
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*
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* Precondition: buffer->size < buffer->expected
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*/
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ssize_t bufferRead(Buffer* buffer, int fd);
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/**
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* Prepares a buffer to be written out.
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*/
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void bufferPrepareForWrite(Buffer* buffer);
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/**
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* Writes data from buffer to the given fd. Returns -1 and sets errno in case
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* of an error. Updates buffer->remaining and returns the number of remaining
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* bytes to be written after a successful write.
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*
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* Precondition: buffer->remaining > 0
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*/
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ssize_t bufferWrite(Buffer* buffer, int fd);
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#ifdef __cplusplus
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}
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#endif
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#endif /* __BUFFER_H */
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