GRASS GIS 8 Programmer's Manual 8.3.2(2024)-exported
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cmprzstd.c
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1/*
2 ****************************************************************************
3 * -- GRASS Development Team --
4 *
5 * MODULE: GRASS gis library
6 * FILENAME: cmprzstd.c
7 * AUTHOR(S): Eric G. Miller <egm2@jps.net>
8 * Markus Metz
9 * PURPOSE: To provide an interface to ZSTD for compressing and
10 * decompressing data using ZSTD. It's primary use is in
11 * the storage and reading of GRASS floating point rasters.
12 *
13 * ALGORITHM: http://www.zstd.net
14 * DATE CREATED: Dec 18 2017
15 * COPYRIGHT: (C) 2017 by the GRASS Development Team
16 *
17 * This program is free software under the GNU General Public
18 * License (version 2 or greater). Read the file COPYING that
19 * comes with GRASS for details.
20 *
21 *****************************************************************************/
22
23/********************************************************************
24 * int *
25 * G_zstd_compress (src, srz_sz, dst, dst_sz) *
26 * int src_sz, dst_sz; *
27 * unsigned char *src, *dst; *
28 * ---------------------------------------------------------------- *
29 * This function is a wrapper around the Zstd compression function. *
30 * It uses an all or nothing call. *
31 * If you need a continuous compression scheme, you'll have to code *
32 * your own. *
33 * In order to do a single pass compression, the input src must be *
34 * copied to a buffer larger than the data. This may cause *
35 * performance degradation. *
36 * *
37 * The function either returns the number of bytes of compressed *
38 * data in dst, or an error code. *
39 * *
40 * Errors include: *
41 * -1 -- Compression failed. *
42 * -2 -- dst is too small. *
43 * *
44 * ================================================================ *
45 * int *
46 * G_zstd_expand (src, src_sz, dst, dst_sz) *
47 * int src_sz, dst_sz; *
48 * unsigned char *src, *dst; *
49 * ---------------------------------------------------------------- *
50 * This function is a wrapper around the zstd decompression *
51 * function. It uses a single pass call. If you need a continuous *
52 * expansion scheme, you'll have to code your own. *
53 * *
54 * The function returns the number of bytes expanded into 'dst' or *
55 * and error code. *
56 * *
57 * Errors include: *
58 * -1 -- Expansion failed. *
59 * *
60 ********************************************************************
61 */
62
63#include <grass/config.h>
64
65#ifdef HAVE_ZSTD_H
66#include <zstd.h>
67#endif
68
69#include <grass/gis.h>
70#include <grass/glocale.h>
71
72int G_zstd_compress_bound(int src_sz)
73{
74 /* ZSTD has a fast version if destLen is large enough
75 * to hold a worst case result
76 */
77#ifndef HAVE_ZSTD_H
79 _("GRASS needs to be compiled with ZSTD for ZSTD compression"));
80 return -1;
81#else
82 return ZSTD_compressBound(src_sz);
83#endif
84}
85
86int G_zstd_compress(unsigned char *src, int src_sz, unsigned char *dst,
87 int dst_sz)
88{
89 int err, nbytes, buf_sz;
90 unsigned char *buf;
91
92#ifndef HAVE_ZSTD_H
94 _("GRASS needs to be compiled with ZSTD for ZSTD compression"));
95 return -1;
96#else
97
98 /* Catch errors early */
99 if (src == NULL || dst == NULL) {
100 if (src == NULL)
101 G_warning(_("No source buffer"));
102
103 if (dst == NULL)
104 G_warning(_("No destination buffer"));
105 return -1;
106 }
107
108 /* Don't do anything if either of these are true */
109 if (src_sz <= 0 || dst_sz <= 0) {
110 if (src_sz <= 0)
111 G_warning(_("Invalid source buffer size %d"), src_sz);
112 if (dst_sz <= 0)
113 G_warning(_("Invalid destination buffer size %d"), dst_sz);
114 return 0;
115 }
116
117 /* Output buffer has to be larger for single pass compression */
118 buf = dst;
119 buf_sz = G_zstd_compress_bound(src_sz);
120 if (buf_sz > dst_sz) {
121 G_warning(
122 "G_zstd_compress(): programmer error, destination is too small");
123 if (NULL ==
124 (buf = (unsigned char *)G_calloc(buf_sz, sizeof(unsigned char))))
125 return -1;
126 }
127 else
128 buf_sz = dst_sz;
129
130 /* Do single pass compression */
131 err = ZSTD_compress((char *)buf, buf_sz, (char *)src, src_sz, 3);
132
133 if (err <= 0 || ZSTD_isError(err)) {
134 G_warning(_("ZSTD compression error %d: %s"), err,
135 ZSTD_getErrorName(err));
136 if (buf != dst)
137 G_free(buf);
138 return -1;
139 }
140 if (err >= src_sz) {
141 /* compression not possible */
142 if (buf != dst)
143 G_free(buf);
144 return -2;
145 }
146
147 /* bytes of compressed data is return value */
148 nbytes = err;
149
150 if (buf != dst) {
151 /* Copy the data from buf to dst */
152 for (err = 0; err < nbytes; err++)
153 dst[err] = buf[err];
154
155 G_free(buf);
156 }
157
158 return nbytes;
159#endif
160}
161
162int G_zstd_expand(unsigned char *src, int src_sz, unsigned char *dst,
163 int dst_sz)
164{
165 int err, nbytes;
166
167#ifndef HAVE_ZSTD_H
169 _("GRASS needs to be compiled with ZSTD for ZSTD compression"));
170 return -1;
171#else
172
173 /* Catch error condition */
174 if (src == NULL || dst == NULL) {
175 if (src == NULL)
176 G_warning(_("No source buffer"));
177
178 if (dst == NULL)
179 G_warning(_("No destination buffer"));
180 return -2;
181 }
182
183 /* Don't do anything if either of these are true */
184 if (src_sz <= 0 || dst_sz <= 0) {
185 if (src_sz <= 0)
186 G_warning(_("Invalid source buffer size %d"), src_sz);
187 if (dst_sz <= 0)
188 G_warning(_("Invalid destination buffer size %d"), dst_sz);
189 return 0;
190 }
191
192 /* Do single pass decompress */
193 err = ZSTD_decompress((char *)dst, dst_sz, (char *)src, src_sz);
194
195 if (err <= 0 || ZSTD_isError(err)) {
196 G_warning(_("ZSTD compression error %d: %s"), err,
197 ZSTD_getErrorName(err));
198 return -1;
199 }
200
201 /* Number of bytes inflated to output stream is return value */
202 nbytes = err;
203
204 if (nbytes != dst_sz) {
205 /* TODO: it is not an error if destination is larger than needed */
206 G_warning(_("Got uncompressed size %d, expected %d"), (int)nbytes,
207 dst_sz);
208 return -1;
209 }
210
211 return nbytes;
212#endif
213}
214
215/* vim: set softtabstop=4 shiftwidth=4 expandtab: */
void G_free(void *buf)
Free allocated memory.
Definition alloc.c:150
#define NULL
Definition ccmath.h:32
int G_zstd_compress_bound(int src_sz)
Definition cmprzstd.c:72
int G_zstd_compress(unsigned char *src, int src_sz, unsigned char *dst, int dst_sz)
Definition cmprzstd.c:86
int G_zstd_expand(unsigned char *src, int src_sz, unsigned char *dst, int dst_sz)
Definition cmprzstd.c:162
void G_fatal_error(const char *msg,...)
Print a fatal error message to stderr.
Definition gis/error.c:159
void G_warning(const char *msg,...)
Print a warning message to stderr.
Definition gis/error.c:203
SYMBOL * err(FILE *fp, SYMBOL *s, char *msg)