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 #pragma once
20 
21 #include <stdbool.h>
22 #include <stddef.h>
23 
24 typedef struct buffer_t buffer_t;
25 
26 // Returns a new buffer of |size| bytes. Returns NULL if a buffer could not be
27 // allocated. |size| must be non-zero. The caller must release this buffer with
28 // |buffer_free|.
29 buffer_t *buffer_new(size_t size);
30 
31 // Creates a new reference to the buffer |buf|. A reference is indistinguishable
32 // from the original: writes to the original will be reflected in the reference
33 // and vice versa. In other words, this function creates an alias to |buf|. The
34 // caller must release the returned buffer with |buffer_free|. Note that releasing
35 // the returned buffer does not release |buf|. |buf| must not be NULL.
36 buffer_t *buffer_new_ref(const buffer_t *buf);
37 
38 // Creates a new reference to the last |slice_size| bytes of |buf|. See
39 // |buffer_new_ref| for a description of references. |slice_size| must be
40 // greater than 0 and may be at most |buffer_length|
41 // (0 < slice_size <= buffer_length). |buf| must not be NULL.
42 buffer_t *buffer_new_slice(const buffer_t *buf, size_t slice_size);
43 
44 // Frees a buffer object. |buf| may be NULL.
45 void buffer_free(buffer_t *buf);
46 
47 // Returns a pointer to a writeable memory region for |buf|. All references
48 // and slices that share overlapping bytes will also be written to when
49 // writing to the returned pointer. The caller may safely write up to
50 // |buffer_length| consecutive bytes starting at the address returned by
51 // this function. |buf| must not be NULL.
52 void *buffer_ptr(const buffer_t *buf);
53 
54 // Returns the length of the writeable memory region referred to by |buf|.
55 // |buf| must not be NULL.
56 size_t buffer_length(const buffer_t *buf);
57