1 /*
2 zip_source_seek.c -- seek to offset
3 Copyright (C) 2014 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 "zipint.h"
36
37
38 ZIP_EXTERN int
zip_source_seek(zip_source_t * src,zip_int64_t offset,int whence)39 zip_source_seek(zip_source_t *src, zip_int64_t offset, int whence)
40 {
41 zip_source_args_seek_t args;
42
43 if (src->source_closed) {
44 return -1;
45 }
46 if (!ZIP_SOURCE_IS_OPEN_READING(src) || (whence != SEEK_SET && whence != SEEK_CUR && whence != SEEK_END)) {
47 zip_error_set(&src->error, ZIP_ER_INVAL, 0);
48 return -1;
49 }
50
51 args.offset = offset;
52 args.whence = whence;
53
54 return (_zip_source_call(src, &args, sizeof(args), ZIP_SOURCE_SEEK) < 0 ? -1 : 0);
55 }
56
57
58 zip_int64_t
zip_source_seek_compute_offset(zip_uint64_t offset,zip_uint64_t length,void * data,zip_uint64_t data_length,zip_error_t * error)59 zip_source_seek_compute_offset(zip_uint64_t offset, zip_uint64_t length, void *data, zip_uint64_t data_length, zip_error_t *error)
60 {
61 zip_int64_t new_offset;
62 zip_source_args_seek_t *args = ZIP_SOURCE_GET_ARGS(zip_source_args_seek_t, data, data_length, error);
63
64 if (args == NULL) {
65 return -1;
66 }
67
68 switch (args->whence) {
69 case SEEK_CUR:
70 new_offset = (zip_int64_t)offset + args->offset;
71 break;
72
73 case SEEK_END:
74 new_offset = (zip_int64_t)length + args->offset;
75 break;
76
77 case SEEK_SET:
78 new_offset = args->offset;
79 break;
80
81 default:
82 zip_error_set(error, ZIP_ER_INVAL, 0);
83 return -1;
84 }
85
86 if (new_offset < 0 || (zip_uint64_t)new_offset > length) {
87 zip_error_set(error, ZIP_ER_INVAL, 0);
88 return -1;
89 }
90
91 return new_offset;
92 }
93
