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333
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1 /* vi: set sw=4 ts=4:
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2 *
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3 * cksum.c - produce crc32 checksum value for each input
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4 *
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5 * Copyright 2008 Rob Landley <rob@landley.net>
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6 *
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7 * See http://www.opengroup.org/onlinepubs/009695399/utilities/cksum.html
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8
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336
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9 USE_CKSUM(NEWTOY(cksum, "F", TOYFLAG_BIN))
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333
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10
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11 config CKSUM
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12 bool "cksum"
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13 default y
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14 help
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336
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15 usage: cksum [-F] [file...]
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16
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333
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17 For each file, output crc32 checksum value, length and name of file.
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18 If no files listed, copy from stdin. Filename "-" is a synonym for stdin.
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336
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19
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20 -F Start with 0xffffffff instead of 0.
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333
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21 */
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22
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23 #include "toys.h"
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24
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25 DEFINE_GLOBALS(
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26 unsigned crc_table[256];
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27 )
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28
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29 #define TT this.cksum
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30
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31 static unsigned cksum(unsigned crc, unsigned char c)
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32 {
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33 return (crc<<8)^TT.crc_table[(crc>>24)^c];
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34 }
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35
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36 static void do_cksum(int fd, char *name)
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37 {
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336
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38 unsigned crc = toys.optflags ? 0xffffffff : 0;
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333
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39 uint64_t llen = 0, llen2;
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40
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41 // CRC the data
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42
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43 for (;;) {
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44 int len, i;
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45
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46 len = read(fd, toybuf, sizeof(toybuf));
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47 if (len<0) {
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48 perror_msg("%s",name);
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49 toys.exitval = EXIT_FAILURE;
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50 }
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51 if (len<1) break;
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52
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53 llen += len;
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54 for (i=0; i<len; i++) crc=cksum(crc, toybuf[i]);
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55 }
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56
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57 // CRC the length
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58
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59 llen2 = llen;
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60 while (llen) {
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61 crc = cksum(crc, llen);
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62 llen >>= 8;
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63 }
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64
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65 printf("%u %"PRIu64, ~crc, llen2);
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66 if (strcmp("-", name)) printf(" %s", name);
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67 xputc('\n');
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68 }
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69
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70 void cksum_main(void)
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71 {
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72 crc_init(TT.crc_table);
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73 loopfiles(toys.optargs, do_cksum);
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74 }
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