The Android Open Source Project | dd7bc33 | 2009-03-03 19:32:55 -0800 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2007 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | /** |
| 18 | * Byte buffer utilities. |
| 19 | */ |
| 20 | |
| 21 | #ifndef __BUFFER_H |
| 22 | #define __BUFFER_H |
| 23 | |
| 24 | #ifdef __cplusplus |
| 25 | extern "C" { |
| 26 | #endif |
| 27 | |
| 28 | #include <stdlib.h> |
| 29 | |
| 30 | /** |
| 31 | * Byte buffer of known size. Keeps track of how much data has been read |
| 32 | * into or written out of the buffer. |
| 33 | */ |
| 34 | typedef struct { |
| 35 | /** Buffered data. */ |
| 36 | char* data; |
| 37 | |
| 38 | union { |
| 39 | /** For reading. # of bytes we expect. */ |
| 40 | size_t expected; |
| 41 | |
| 42 | /** For writing. # of bytes to write. */ |
| 43 | size_t remaining; |
| 44 | }; |
| 45 | |
| 46 | /** Actual # of bytes in the buffer. */ |
| 47 | size_t size; |
| 48 | |
| 49 | /** Amount of memory allocated for this buffer. */ |
| 50 | size_t capacity; |
| 51 | } Buffer; |
| 52 | |
| 53 | /** |
| 54 | * Returns true if all data has been read into the buffer. |
| 55 | */ |
| 56 | #define bufferReadComplete(buffer) (buffer->expected == buffer->size) |
| 57 | |
| 58 | /** |
| 59 | * Returns true if the buffer has been completely written. |
| 60 | */ |
| 61 | #define bufferWriteComplete(buffer) (buffer->remaining == 0) |
| 62 | |
| 63 | /** |
| 64 | * Creates a new buffer with the given initial capacity. |
| 65 | */ |
| 66 | Buffer* bufferCreate(size_t initialCapacity); |
| 67 | |
| 68 | /** |
| 69 | * Wraps an existing byte array. |
| 70 | */ |
| 71 | Buffer* bufferWrap(char* data, size_t capacity, size_t size); |
| 72 | |
| 73 | /** |
| 74 | * Frees and its data. |
| 75 | */ |
| 76 | void bufferFree(Buffer* buffer); |
| 77 | |
| 78 | /** |
| 79 | * Prepares buffer to read 'expected' number of bytes. Expands capacity if |
| 80 | * necessary. Returns 0 if successful or -1 if an error occurs allocating |
| 81 | * memory. |
| 82 | */ |
| 83 | int bufferPrepareForRead(Buffer* buffer, size_t expected); |
| 84 | |
| 85 | /** |
| 86 | * Reads some data into a buffer. Returns -1 in case of an error and sets |
| 87 | * errno (see read()). Returns 0 for EOF. Updates buffer->size and returns |
| 88 | * the new size after a succesful read. |
| 89 | * |
| 90 | * Precondition: buffer->size < buffer->expected |
| 91 | */ |
| 92 | ssize_t bufferRead(Buffer* buffer, int fd); |
| 93 | |
| 94 | /** |
| 95 | * Prepares a buffer to be written out. |
| 96 | */ |
| 97 | void bufferPrepareForWrite(Buffer* buffer); |
| 98 | |
| 99 | /** |
| 100 | * Writes data from buffer to the given fd. Returns -1 and sets errno in case |
| 101 | * of an error. Updates buffer->remaining and returns the number of remaining |
| 102 | * bytes to be written after a successful write. |
| 103 | * |
| 104 | * Precondition: buffer->remaining > 0 |
| 105 | */ |
| 106 | ssize_t bufferWrite(Buffer* buffer, int fd); |
| 107 | |
| 108 | #ifdef __cplusplus |
| 109 | } |
| 110 | #endif |
| 111 | |
| 112 | #endif /* __BUFFER_H */ |