1 /****************************************************************************** 2 * 3 * Copyright (C) 2014 Google, Inc. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at: 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 ******************************************************************************/ 18 19 #ifndef _BUFFER_H_ 20 #define _BUFFER_H_ 21 22 #include <stdbool.h> 23 #include <stddef.h> 24 25 typedef struct buffer_t buffer_t; 26 27 // Returns a new buffer of |size| bytes. Returns NULL if a buffer could not be 28 // allocated. |size| must be non-zero. The caller must release this buffer with 29 // |buffer_free|. 30 buffer_t *buffer_new(size_t size); 31 32 // Creates a new reference to the buffer |buf|. A reference is indistinguishable 33 // from the original: writes to the original will be reflected in the reference 34 // and vice versa. In other words, this function creates an alias to |buf|. The 35 // caller must release the returned buffer with |buffer_free|. Note that releasing 36 // the returned buffer does not release |buf|. |buf| must not be NULL. 37 buffer_t *buffer_new_ref(const buffer_t *buf); 38 39 // Creates a new reference to the last |slice_size| bytes of |buf|. See 40 // |buffer_new_ref| for a description of references. |slice_size| must be 41 // greater than 0 and may be at most |buffer_length| 42 // (0 < slice_size <= buffer_length). |buf| must not be NULL. 43 buffer_t *buffer_new_slice(const buffer_t *buf, size_t slice_size); 44 45 // Frees a buffer object. |buf| may be NULL. 46 void buffer_free(buffer_t *buf); 47 48 // Returns a pointer to a writeable memory region for |buf|. All references 49 // and slices that share overlapping bytes will also be written to when 50 // writing to the returned pointer. The caller may safely write up to 51 // |buffer_length| consecutive bytes starting at the address returned by 52 // this function. |buf| must not be NULL. 53 void *buffer_ptr(const buffer_t *buf); 54 55 // Returns the length of the writeable memory region referred to by |buf|. 56 // |buf| must not be NULL. 57 size_t buffer_length(const buffer_t *buf); 58 59 #endif /*_BUFFER_H_*/ 60
