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Diffstat (limited to 'libcutils/buffer.h')
-rw-r--r-- | libcutils/buffer.h | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/libcutils/buffer.h b/libcutils/buffer.h new file mode 100644 index 000000000..d8bc108ee --- /dev/null +++ b/libcutils/buffer.h @@ -0,0 +1,112 @@ +/* + * 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 */ |