1 /*
2 zip_source_crc.c -- pass-through source that calculates CRC32 and size
3 Copyright (c) 2009-2017 Dieter Baron and Thomas Klausner
4
5 This file is part of libzip, a library to manipulate ZIP archives.
6 The authors can be contacted at <libzip@nih.at>
7
8 Redistribution and use in source and binary forms, with or without
9 modification, are permitted provided that the following conditions
10 are met:
11 1. Redistributions of source code must retain the above copyright
12 notice, this list of conditions and the following disclaimer.
13 2. Redistributions in binary form must reproduce the above copyright
14 notice, this list of conditions and the following disclaimer in
15 the documentation and/or other materials provided with the
16 distribution.
17 3. The names of the authors may not be used to endorse or promote
18 products derived from this software without specific prior
19 written permission.
20
21 THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
22 OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
25 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
27 GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
29 IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
30 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
31 IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34
35 #include <stdlib.h>
36 #include <string.h>
37 #include <limits.h>
38
39 #include "zipint.h"
40
41 struct crc_context {
42 int validate; /* whether to check CRC on EOF and return error on mismatch */
43 int crc_complete; /* whether CRC was computed for complete file */
44 zip_error_t error;
45 zip_uint64_t size;
46 zip_uint64_t position; /* current reading position */
47 zip_uint64_t crc_position; /* how far we've computed the CRC */
48 zip_uint32_t crc;
49 };
50
51 static zip_int64_t crc_read(zip_source_t *, void *, void *, zip_uint64_t, zip_source_cmd_t);
52
53
54 zip_source_t *
zip_source_crc(zip_t * za,zip_source_t * src,int validate)55 zip_source_crc(zip_t *za, zip_source_t *src, int validate)
56 {
57 struct crc_context *ctx;
58
59 if (src == NULL) {
60 zip_error_set(&za->error, ZIP_ER_INVAL, 0);
61 return NULL;
62 }
63
64 if ((ctx=(struct crc_context *)malloc(sizeof(*ctx))) == NULL) {
65 zip_error_set(&za->error, ZIP_ER_MEMORY, 0);
66 return NULL;
67 }
68
69 zip_error_init(&ctx->error);
70 ctx->validate = validate;
71 ctx->crc_complete = 0;
72 ctx->crc_position = 0;
73 ctx->crc = (zip_uint32_t)crc32(0, NULL, 0);
74 ctx->size = 0;
75
76 return zip_source_layered(za, src, crc_read, ctx);
77 }
78
79
80 static zip_int64_t
crc_read(zip_source_t * src,void * _ctx,void * data,zip_uint64_t len,zip_source_cmd_t cmd)81 crc_read(zip_source_t *src, void *_ctx, void *data, zip_uint64_t len, zip_source_cmd_t cmd)
82 {
83 struct crc_context *ctx;
84 zip_int64_t n;
85
86 ctx = (struct crc_context *)_ctx;
87
88 switch (cmd) {
89 case ZIP_SOURCE_OPEN:
90 ctx->position = 0;
91 return 0;
92
93 case ZIP_SOURCE_READ:
94 if ((n = zip_source_read(src, data, len)) < 0) {
95 _zip_error_set_from_source(&ctx->error, src);
96 return -1;
97 }
98
99 if (n == 0) {
100 if (ctx->crc_position == ctx->position) {
101 ctx->crc_complete = 1;
102 ctx->size = ctx->position;
103
104 if (ctx->validate) {
105 struct zip_stat st;
106
107 if (zip_source_stat(src, &st) < 0) {
108 _zip_error_set_from_source(&ctx->error, src);
109 return -1;
110 }
111
112 if ((st.valid & ZIP_STAT_CRC) && st.crc != ctx->crc) {
113 zip_error_set(&ctx->error, ZIP_ER_CRC, 0);
114 return -1;
115 }
116 if ((st.valid & ZIP_STAT_SIZE) && st.size != ctx->size) {
117 zip_error_set(&ctx->error, ZIP_ER_INCONS, 0);
118 return -1;
119 }
120 }
121 }
122 }
123 else if (!ctx->crc_complete && ctx->position <= ctx->crc_position) {
124 zip_uint64_t i, nn;
125
126 for (i = ctx->crc_position - ctx->position; i < (zip_uint64_t)n; i += nn) {
127 nn = ZIP_MIN(UINT_MAX, (zip_uint64_t)n-i);
128
129 ctx->crc = (zip_uint32_t)crc32(ctx->crc, (const Bytef *)data+i, (uInt)nn);
130 ctx->crc_position += nn;
131 }
132 }
133 ctx->position += (zip_uint64_t)n;
134 return n;
135
136 case ZIP_SOURCE_CLOSE:
137 return 0;
138
139 case ZIP_SOURCE_STAT:
140 {
141 zip_stat_t *st;
142
143 st = (zip_stat_t *)data;
144
145 if (ctx->crc_complete) {
146 /* TODO: Set comp_size, comp_method, encryption_method?
147 After all, this only works for uncompressed data. */
148 st->size = ctx->size;
149 st->crc = ctx->crc;
150 st->comp_size = ctx->size;
151 st->comp_method = ZIP_CM_STORE;
152 st->encryption_method = ZIP_EM_NONE;
153 st->valid |= ZIP_STAT_SIZE|ZIP_STAT_CRC|ZIP_STAT_COMP_SIZE|ZIP_STAT_COMP_METHOD|ZIP_STAT_ENCRYPTION_METHOD;;
154 }
155 return 0;
156 }
157
158 case ZIP_SOURCE_ERROR:
159 return zip_error_to_data(&ctx->error, data, len);
160
161 case ZIP_SOURCE_FREE:
162 free(ctx);
163 return 0;
164
165 case ZIP_SOURCE_SUPPORTS:
166 {
167 zip_int64_t mask = zip_source_supports(src);
168
169 if (mask < 0) {
170 _zip_error_set_from_source(&ctx->error, src);
171 return -1;
172 }
173
174 return mask & ~zip_source_make_command_bitmap(ZIP_SOURCE_BEGIN_WRITE, ZIP_SOURCE_COMMIT_WRITE, ZIP_SOURCE_ROLLBACK_WRITE, ZIP_SOURCE_SEEK_WRITE, ZIP_SOURCE_TELL_WRITE, ZIP_SOURCE_REMOVE, -1);
175 }
176
177 case ZIP_SOURCE_SEEK:
178 {
179 zip_int64_t new_position;
180 zip_source_args_seek_t *args = ZIP_SOURCE_GET_ARGS(zip_source_args_seek_t, data, len, &ctx->error);
181
182 if (args == NULL) {
183 return -1;
184 }
185 if (zip_source_seek(src, args->offset, args->whence) < 0 || (new_position = zip_source_tell(src)) < 0) {
186 _zip_error_set_from_source(&ctx->error, src);
187 return -1;
188 }
189
190 ctx->position = (zip_uint64_t)new_position;
191
192 return 0;
193 }
194
195 case ZIP_SOURCE_TELL:
196 return (zip_int64_t)ctx->position;
197
198 default:
199 zip_error_set(&ctx->error, ZIP_ER_OPNOTSUPP, 0);
200 return -1;
201 }
202 }
203
