/src/libzip/lib/zip_source_crc.c

Source
/*
  zip_source_crc.c -- pass-through source that calculates CRC32 and size
  Copyright (C) 2009-2025 Dieter Baron and Thomas Klausner

  This file is part of libzip, a library to manipulate ZIP archives.
  The authors can be contacted at <info@libzip.org>

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions
  are met:
  1. Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in
     the documentation and/or other materials provided with the
     distribution.
  3. The names of the authors may not be used to endorse or promote
     products derived from this software without specific prior
     written permission.

  THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
  IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
  IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/


#include <limits.h>
#include <stdlib.h>
#include <zlib.h>

#include "zipint.h"

struct crc_context {
    int validate;     /* whether to check CRC on EOF and return error on mismatch */
    int crc_complete; /* whether CRC was computed for complete file */
    zip_error_t error;
    zip_uint64_t size;
    zip_uint64_t position;     /* current reading position */
    zip_uint64_t crc_position; /* how far we've computed the CRC */
    zip_uint32_t crc;
};

static zip_int64_t crc_read(zip_source_t *, void *, void *, zip_uint64_t, zip_source_cmd_t);
static zip_int64_t validate_crc(struct crc_context *ctx, zip_source_t *src);

zip_source_t *zip_source_crc_create(zip_source_t *src, int validate, zip_error_t *error) {
    struct crc_context *ctx;
    zip_source_t *new_src;

    if (src == NULL) {
        zip_error_set(error, ZIP_ER_INVAL, 0);
        return NULL;
    }

    if ((ctx = (struct crc_context *)malloc(sizeof(*ctx))) == NULL) {
        zip_error_set(error, ZIP_ER_MEMORY, 0);
        return NULL;
    }

    zip_error_init(&ctx->error);
    ctx->validate = validate;
    ctx->crc_complete = 0;
    ctx->crc_position = 0;
    ctx->crc = (zip_uint32_t)crc32(0, NULL, 0);
    ctx->size = 0;

    new_src = zip_source_layered_create(src, crc_read, ctx, error);
    if (new_src == NULL) {
        free(ctx);
        return NULL;
    }
    return new_src;
}


static zip_int64_t crc_read(zip_source_t *src, void *_ctx, void *data, zip_uint64_t len, zip_source_cmd_t cmd) {
    struct crc_context *ctx;
    zip_int64_t n;

    ctx = (struct crc_context *)_ctx;

    switch (cmd) {
    case ZIP_SOURCE_OPEN:
        ctx->position = 0;
        return 0;

    case ZIP_SOURCE_READ:
        if ((n = zip_source_read(src, data, len)) < 0) {
            zip_error_set_from_source(&ctx->error, src);
            return -1;
        }

        if (n == 0) {
            return validate_crc(ctx, src);
        }
        else {
            /*
             We can only compute the CRC data in the correct order. So we update the CRC for data read this time that starts at ctx->crc_position.

             If we already computed the CRC for the whole file, or if there is a gap between ctx->crc_position and the start of new data, or if we already computed the CRC for all new data read, we don't update the CRC.

             ctx->position is the position of the first byte in data.

             ctx->crc_position is the position of the first byte in data that has not been included  in the CRC yet.

             Therefore, we want to compute the CRC for data[ctx->crc_position - ctx->position .. n-1].

            */
            if (!ctx->crc_complete && ctx->position <= ctx->crc_position && ctx->crc_position < ctx->position + (zip_uint64_t)n) {
                zip_uint64_t i, nn;

                for (i = ctx->crc_position - ctx->position; i < (zip_uint64_t)n; i += nn) {
                    nn = ZIP_MIN(UINT_MAX, (zip_uint64_t)n - i);

                    ctx->crc = (zip_uint32_t)crc32(ctx->crc, (const Bytef *)data + i, (uInt)nn);
                    ctx->crc_position += nn;
                }
            }
        }
        ctx->position += (zip_uint64_t)n;
        return n;

    case ZIP_SOURCE_CLOSE: {
        zip_int64_t ret = zip_source_at_eof(src);
        if (ret < 0) {
            zip_error_set_from_source(&ctx->error, src);
            return -1;
        }
        else if (ret == 1) {
            return validate_crc(ctx, src);
        }
        else {
            return 0;
        }
    }

    case ZIP_SOURCE_STAT: {
        zip_stat_t *st;

        st = (zip_stat_t *)data;

        if (ctx->crc_complete) {
            if ((st->valid & ZIP_STAT_SIZE) && st->size != ctx->size) {
                zip_error_set(&ctx->error, ZIP_ER_DATA_LENGTH, 0);
                return -1;
            }
            /* TODO: Set comp_size, comp_method, encryption_method?
                    After all, this only works for uncompressed data. */
            st->size = ctx->size;
            st->crc = ctx->crc;
            st->comp_size = ctx->size;
            st->comp_method = ZIP_CM_STORE;
            st->encryption_method = ZIP_EM_NONE;
            st->valid |= ZIP_STAT_SIZE | ZIP_STAT_CRC | ZIP_STAT_COMP_SIZE | ZIP_STAT_COMP_METHOD | ZIP_STAT_ENCRYPTION_METHOD;
        }
        return 0;
    }

    case ZIP_SOURCE_ERROR:
        return zip_error_to_data(&ctx->error, data, len);

    case ZIP_SOURCE_FREE:
        free(ctx);
        return 0;

    case ZIP_SOURCE_SUPPORTS: {
        zip_int64_t mask = zip_source_supports(src);

        if (mask < 0) {
            zip_error_set_from_source(&ctx->error, src);
            return -1;
        }

        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, ZIP_SOURCE_GET_FILE_ATTRIBUTES, -1);
        mask |= zip_source_make_command_bitmap(ZIP_SOURCE_FREE, -1);
        return mask;
    }

    case ZIP_SOURCE_SEEK: {
        zip_int64_t new_position;
        zip_source_args_seek_t *args = ZIP_SOURCE_GET_ARGS(zip_source_args_seek_t, data, len, &ctx->error);

        if (args == NULL) {
            return -1;
        }
        if (zip_source_seek(src, args->offset, args->whence) < 0 || (new_position = zip_source_tell(src)) < 0) {
            zip_error_set_from_source(&ctx->error, src);
            return -1;
        }

        ctx->position = (zip_uint64_t)new_position;

        return 0;
    }

    case ZIP_SOURCE_TELL:
        return (zip_int64_t)ctx->position;

    default:
        return zip_source_pass_to_lower_layer(src, data, len, cmd);
    }
}

zip_int64_t validate_crc(struct crc_context *ctx, zip_source_t *src) {
    struct zip_stat st;

    ctx->size = ctx->position;

    if (ctx->validate) {
        if (zip_source_stat(src, &st) < 0) {
            zip_error_set_from_source(&ctx->error, src);
            return -1;
        }
    }

    if (ctx->crc_position == ctx->position) {
        ctx->crc_complete = 1;

        if (ctx->validate) {
            if ((st.valid & ZIP_STAT_CRC) && st.crc != ctx->crc) {
                zip_error_set(&ctx->error, ZIP_ER_CRC, 0);
                return -1;
            }
        }
    }

    if (ctx->validate) {
        if ((st.valid & ZIP_STAT_SIZE) && st.size != ctx->size) {
            /* We don't have the index here, but the caller should know which file they are reading from. */
            zip_error_set(&ctx->error, ZIP_ER_INCONS, MAKE_DETAIL_WITH_INDEX(ZIP_ER_DETAIL_INVALID_FILE_LENGTH, MAX_DETAIL_INDEX));
            return -1;
        }
    }

    return 0;
}

Coverage Report

Created: 2026-08-25 06:40

Line	Count	Source
1		/*
2		zip_source_crc.c -- pass-through source that calculates CRC32 and size
3		Copyright (C) 2009-2025 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 <info@libzip.org>
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 <limits.h>
36		#include <stdlib.h>
37		#include <zlib.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		static zip_int64_t validate_crc(struct crc_context ctx, zip_source_t src);
53
54	10.9k	zip_source_t zip_source_crc_create(zip_source_t src, int validate, zip_error_t *error) {
55	10.9k	struct crc_context *ctx;
56	10.9k	zip_source_t *new_src;
57
58	10.9k	if (src == NULL) {
59	0	zip_error_set(error, ZIP_ER_INVAL, 0);
60	0	return NULL;
61	0	}
62
63	10.9k	if ((ctx = (struct crc_context )malloc(sizeof(ctx))) == NULL) {
64	0	zip_error_set(error, ZIP_ER_MEMORY, 0);
65	0	return NULL;
66	0	}
67
68	10.9k	zip_error_init(&ctx->error);
69	10.9k	ctx->validate = validate;
70	10.9k	ctx->crc_complete = 0;
71	10.9k	ctx->crc_position = 0;
72	10.9k	ctx->crc = (zip_uint32_t)crc32(0, NULL, 0);
73	10.9k	ctx->size = 0;
74
75	10.9k	new_src = zip_source_layered_create(src, crc_read, ctx, error);
76	10.9k	if (new_src == NULL) {
77	0	free(ctx);
78	0	return NULL;
79	0	}
80	10.9k	return new_src;
81	10.9k	}
82
83
84	65.7k	static zip_int64_t crc_read(zip_source_t src, void _ctx, void *data, zip_uint64_t len, zip_source_cmd_t cmd) {
85	65.7k	struct crc_context *ctx;
86	65.7k	zip_int64_t n;
87
88	65.7k	ctx = (struct crc_context *)_ctx;
89
90	65.7k	switch (cmd) {
91	9.82k	case ZIP_SOURCE_OPEN:
92	9.82k	ctx->position = 0;
93	9.82k	return 0;
94
95	12.7k	case ZIP_SOURCE_READ:
96	12.7k	if ((n = zip_source_read(src, data, len)) < 0) {
97	3.18k	zip_error_set_from_source(&ctx->error, src);
98	3.18k	return -1;
99	3.18k	}
100
101	9.60k	if (n == 0) {
102	2.03k	return validate_crc(ctx, src);
103	2.03k	}
104	7.57k	else {
105		/*
106		We can only compute the CRC data in the correct order. So we update the CRC for data read this time that starts at ctx->crc_position.
107
108		If we already computed the CRC for the whole file, or if there is a gap between ctx->crc_position and the start of new data, or if we already computed the CRC for all new data read, we don't update the CRC.
109
110		ctx->position is the position of the first byte in data.
111
112		ctx->crc_position is the position of the first byte in data that has not been included in the CRC yet.
113
114		Therefore, we want to compute the CRC for data[ctx->crc_position - ctx->position .. n-1].
115
116		*/
117	7.57k	if (!ctx->crc_complete && ctx->position <= ctx->crc_position && ctx->crc_position < ctx->position + (zip_uint64_t)n) {
118	7.57k	zip_uint64_t i, nn;
119
120	15.1k	for (i = ctx->crc_position - ctx->position; i < (zip_uint64_t)n; i += nn) {
121	7.57k	nn = ZIP_MIN(UINT_MAX, (zip_uint64_t)n - i);
122
123	7.57k	ctx->crc = (zip_uint32_t)crc32(ctx->crc, (const Bytef *)data + i, (uInt)nn);
124	7.57k	ctx->crc_position += nn;
125	7.57k	}
126	7.57k	}
127	7.57k	}
128	7.57k	ctx->position += (zip_uint64_t)n;
129	7.57k	return n;
130
131	9.82k	case ZIP_SOURCE_CLOSE: {
132	9.82k	zip_int64_t ret = zip_source_at_eof(src);
133	9.82k	if (ret < 0) {
134	2.79k	zip_error_set_from_source(&ctx->error, src);
135	2.79k	return -1;
136	2.79k	}
137	7.02k	else if (ret == 1) {
138	5.50k	return validate_crc(ctx, src);
139	5.50k	}
140	1.51k	else {
141	1.51k	return 0;
142	1.51k	}
143	9.82k	}
144
145	0	case ZIP_SOURCE_STAT: {
146	0	zip_stat_t *st;
147
148	0	st = (zip_stat_t *)data;
149
150	0	if (ctx->crc_complete) {
151	0	if ((st->valid & ZIP_STAT_SIZE) && st->size != ctx->size) {
152	0	zip_error_set(&ctx->error, ZIP_ER_DATA_LENGTH, 0);
153	0	return -1;
154	0	}
155		/* TODO: Set comp_size, comp_method, encryption_method?
156		After all, this only works for uncompressed data. */
157	0	st->size = ctx->size;
158	0	st->crc = ctx->crc;
159	0	st->comp_size = ctx->size;
160	0	st->comp_method = ZIP_CM_STORE;
161	0	st->encryption_method = ZIP_EM_NONE;
162	0	st->valid \|= ZIP_STAT_SIZE \| ZIP_STAT_CRC \| ZIP_STAT_COMP_SIZE \| ZIP_STAT_COMP_METHOD \| ZIP_STAT_ENCRYPTION_METHOD;
163	0	}
164	0	return 0;
165	0	}
166
167	11.3k	case ZIP_SOURCE_ERROR:
168	11.3k	return zip_error_to_data(&ctx->error, data, len);
169
170	10.9k	case ZIP_SOURCE_FREE:
171	10.9k	free(ctx);
172	10.9k	return 0;
173
174	10.9k	case ZIP_SOURCE_SUPPORTS: {
175	10.9k	zip_int64_t mask = zip_source_supports(src);
176
177	10.9k	if (mask < 0) {
178	0	zip_error_set_from_source(&ctx->error, src);
179	0	return -1;
180	0	}
181
182	10.9k	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, ZIP_SOURCE_GET_FILE_ATTRIBUTES, -1);
183	10.9k	mask \|= zip_source_make_command_bitmap(ZIP_SOURCE_FREE, -1);
184	10.9k	return mask;
185	10.9k	}
186
187	0	case ZIP_SOURCE_SEEK: {
188	0	zip_int64_t new_position;
189	0	zip_source_args_seek_t *args = ZIP_SOURCE_GET_ARGS(zip_source_args_seek_t, data, len, &ctx->error);
190
191	0	if (args == NULL) {
192	0	return -1;
193	0	}
194	0	if (zip_source_seek(src, args->offset, args->whence) < 0 \|\| (new_position = zip_source_tell(src)) < 0) {
195	0	zip_error_set_from_source(&ctx->error, src);
196	0	return -1;
197	0	}
198
199	0	ctx->position = (zip_uint64_t)new_position;
200
201	0	return 0;
202	0	}
203
204	0	case ZIP_SOURCE_TELL:
205	0	return (zip_int64_t)ctx->position;
206
207	0	default:
208	0	return zip_source_pass_to_lower_layer(src, data, len, cmd);
209	65.7k	}
210	65.7k	}
211
212	7.54k	zip_int64_t validate_crc(struct crc_context ctx, zip_source_t src) {
213	7.54k	struct zip_stat st;
214
215	7.54k	ctx->size = ctx->position;
216
217	7.54k	if (ctx->validate) {
218	7.54k	if (zip_source_stat(src, &st) < 0) {
219	0	zip_error_set_from_source(&ctx->error, src);
220	0	return -1;
221	0	}
222	7.54k	}
223
224	7.54k	if (ctx->crc_position == ctx->position) {
225	7.54k	ctx->crc_complete = 1;
226
227	7.54k	if (ctx->validate) {
228	7.54k	if ((st.valid & ZIP_STAT_CRC) && st.crc != ctx->crc) {
229	5.25k	zip_error_set(&ctx->error, ZIP_ER_CRC, 0);
230	5.25k	return -1;
231	5.25k	}
232	7.54k	}
233	7.54k	}
234
235	2.28k	if (ctx->validate) {
236	2.28k	if ((st.valid & ZIP_STAT_SIZE) && st.size != ctx->size) {
237		/* We don't have the index here, but the caller should know which file they are reading from. */
238	148	zip_error_set(&ctx->error, ZIP_ER_INCONS, MAKE_DETAIL_WITH_INDEX(ZIP_ER_DETAIL_INVALID_FILE_LENGTH, MAX_DETAIL_INDEX));
239	148	return -1;
240	148	}
241	2.28k	}
242
243	2.13k	return 0;
244	2.28k	}