4
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1 /* |
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2 zip_filerange_crc.c -- compute CRC32 for a range of a file |
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3 Copyright (C) 2008-2015 Dieter Baron and Thomas Klausner |
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4 |
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5 This file is part of libzip, a library to manipulate ZIP archives. |
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6 The authors can be contacted at <libzip@nih.at> |
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7 |
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8 Redistribution and use in source and binary forms, with or without |
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9 modification, are permitted provided that the following conditions |
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10 are met: |
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11 1. Redistributions of source code must retain the above copyright |
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12 notice, this list of conditions and the following disclaimer. |
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13 2. Redistributions in binary form must reproduce the above copyright |
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14 notice, this list of conditions and the following disclaimer in |
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15 the documentation and/or other materials provided with the |
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16 distribution. |
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17 3. The names of the authors may not be used to endorse or promote |
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18 products derived from this software without specific prior |
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19 written permission. |
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20 |
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21 THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS |
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22 OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
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23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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24 ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY |
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25 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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26 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE |
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27 GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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28 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER |
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29 IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
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30 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN |
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31 IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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32 */ |
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33 |
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34 |
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35 #include <stdio.h> |
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36 |
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37 #include "zipint.h" |
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38 |
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39 |
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40 |
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41 int |
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42 _zip_filerange_crc(zip_source_t *src, zip_uint64_t start, zip_uint64_t len, uLong *crcp, zip_error_t *error) |
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43 { |
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44 Bytef buf[BUFSIZE]; |
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45 zip_int64_t n; |
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46 |
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47 *crcp = crc32(0L, Z_NULL, 0); |
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48 |
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49 if (start > ZIP_INT64_MAX) { |
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50 zip_error_set(error, ZIP_ER_SEEK, EFBIG); |
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51 return -1; |
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52 } |
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53 |
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54 if (zip_source_seek(src, (zip_int64_t)start, SEEK_SET) != 0) { |
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55 _zip_error_set_from_source(error, src); |
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56 return -1; |
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57 } |
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58 |
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59 while (len > 0) { |
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60 n = (zip_int64_t)(len > BUFSIZE ? BUFSIZE : len); |
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61 if ((n = zip_source_read(src, buf, (zip_uint64_t)n)) < 0) { |
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62 _zip_error_set_from_source(error, src); |
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63 return -1; |
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64 } |
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65 if (n == 0) { |
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66 zip_error_set(error, ZIP_ER_EOF, 0); |
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67 return -1; |
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68 } |
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69 |
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70 *crcp = crc32(*crcp, buf, (uInt)n); |
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71 |
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72 len -= (zip_uint64_t)n; |
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73 } |
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74 |
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75 return 0; |
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76 } |