Developer Documentation
snappy-c.h
1 /*
2  * Copyright 2011 Martin Gieseking <martin.gieseking@uos.de>.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are
6  * met:
7  *
8  * * Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  * * Redistributions in binary form must reproduce the above
11  * copyright notice, this list of conditions and the following disclaimer
12  * in the documentation and/or other materials provided with the
13  * distribution.
14  * * Neither the name of Google Inc. nor the names of its
15  * contributors may be used to endorse or promote products derived from
16  * this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  *
30  * Plain C interface (a wrapper around the C++ implementation).
31  */
32 
33 #ifndef THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_C_H_
34 #define THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_C_H_
35 
36 #ifdef __cplusplus
37 extern "C" {
38 #endif
39 
40 #include <stddef.h>
41 
42 /*
43  * Return values; see the documentation for each function to know
44  * what each can return.
45  */
46 typedef enum {
47  SNAPPY_OK = 0,
48  SNAPPY_INVALID_INPUT = 1,
49  SNAPPY_BUFFER_TOO_SMALL = 2
50 } snappy_status;
51 
52 /*
53  * Takes the data stored in "input[0..input_length-1]" and stores
54  * it in the array pointed to by "compressed".
55  *
56  * <compressed_length> signals the space available in "compressed".
57  * If it is not at least equal to "snappy_max_compressed_length(input_length)",
58  * SNAPPY_BUFFER_TOO_SMALL is returned. After successful compression,
59  * <compressed_length> contains the true length of the compressed output,
60  * and SNAPPY_OK is returned.
61  *
62  * Example:
63  * size_t output_length = snappy_max_compressed_length(input_length);
64  * char* output = (char*)malloc(output_length);
65  * if (snappy_compress(input, input_length, output, &output_length)
66  * == SNAPPY_OK) {
67  * ... Process(output, output_length) ...
68  * }
69  * free(output);
70  */
71 snappy_status snappy_compress(const char* input,
72  size_t input_length,
73  char* compressed,
74  size_t* compressed_length);
75 
76 /*
77  * Given data in "compressed[0..compressed_length-1]" generated by
78  * calling the snappy_compress routine, this routine stores
79  * the uncompressed data to
80  * uncompressed[0..uncompressed_length-1].
81  * Returns failure (a value not equal to SNAPPY_OK) if the message
82  * is corrupted and could not be decrypted.
83  *
84  * <uncompressed_length> signals the space available in "uncompressed".
85  * If it is not at least equal to the value returned by
86  * snappy_uncompressed_length for this stream, SNAPPY_BUFFER_TOO_SMALL
87  * is returned. After successful decompression, <uncompressed_length>
88  * contains the true length of the decompressed output.
89  *
90  * Example:
91  * size_t output_length;
92  * if (snappy_uncompressed_length(input, input_length, &output_length)
93  * != SNAPPY_OK) {
94  * ... fail ...
95  * }
96  * char* output = (char*)malloc(output_length);
97  * if (snappy_uncompress(input, input_length, output, &output_length)
98  * == SNAPPY_OK) {
99  * ... Process(output, output_length) ...
100  * }
101  * free(output);
102  */
103 snappy_status snappy_uncompress(const char* compressed,
104  size_t compressed_length,
105  char* uncompressed,
106  size_t* uncompressed_length);
107 
108 /*
109  * Returns the maximal size of the compressed representation of
110  * input data that is "source_length" bytes in length.
111  */
112 size_t snappy_max_compressed_length(size_t source_length);
113 
114 /*
115  * REQUIRES: "compressed[]" was produced by snappy_compress()
116  * Returns SNAPPY_OK and stores the length of the uncompressed data in
117  * *result normally. Returns SNAPPY_INVALID_INPUT on parsing error.
118  * This operation takes O(1) time.
119  */
120 snappy_status snappy_uncompressed_length(const char* compressed,
121  size_t compressed_length,
122  size_t* result);
123 
124 /*
125  * Check if the contents of "compressed[]" can be uncompressed successfully.
126  * Does not return the uncompressed data; if so, returns SNAPPY_OK,
127  * or if not, returns SNAPPY_INVALID_INPUT.
128  * Takes time proportional to compressed_length, but is usually at least a
129  * factor of four faster than actual decompression.
130  */
131 snappy_status snappy_validate_compressed_buffer(const char* compressed,
132  size_t compressed_length);
133 
134 #ifdef __cplusplus
135 } // extern "C"
136 #endif
137 
138 #endif /* THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_C_H_ */