1/* cksum.c - produce crc32 checksum value for each input
2 *
3 * Copyright 2008 Rob Landley <rob@landley.net>
4 *
5 * See http://opengroup.org/onlinepubs/9699919799/utilities/cksum.html
6
7USE_CKSUM(NEWTOY(cksum, "HIPLN", TOYFLAG_BIN))
8
9config CKSUM
10  bool "cksum"
11  default y
12  help
13    usage: cksum [-IPLN] [file...]
14
15    For each file, output crc32 checksum value, length and name of file.
16    If no files listed, copy from stdin.  Filename "-" is a synonym for stdin.
17
18    -H	Hexadecimal checksum (defaults to decimal)
19    -L	Little endian (defaults to big endian)
20    -P	Pre-inversion
21    -I	Skip post-inversion
22    -N	Do not include length in CRC calculation
23*/
24
25#define FOR_cksum
26#include "toys.h"
27
28GLOBALS(
29  unsigned crc_table[256];
30)
31
32static unsigned cksum_be(unsigned crc, unsigned char c)
33{
34  return (crc<<8)^TT.crc_table[(crc>>24)^c];
35}
36
37static unsigned cksum_le(unsigned crc, unsigned char c)
38{
39  return TT.crc_table[(crc^c)&0xff] ^ (crc>>8);
40}
41
42static void do_cksum(int fd, char *name)
43{
44  unsigned crc = (toys.optflags & FLAG_P) ? 0xffffffff : 0;
45  uint64_t llen = 0, llen2;
46  unsigned (*cksum)(unsigned crc, unsigned char c);
47
48  cksum = (toys.optflags & FLAG_L) ? cksum_le : cksum_be;
49  // CRC the data
50
51  for (;;) {
52    int len, i;
53
54    len = read(fd, toybuf, sizeof(toybuf));
55    if (len<0) perror_msg_raw(name);
56    if (len<1) break;
57
58    llen += len;
59    for (i=0; i<len; i++) crc=cksum(crc, toybuf[i]);
60  }
61
62  // CRC the length
63
64  llen2 = llen;
65  if (!(toys.optflags & FLAG_N)) {
66    while (llen) {
67      crc = cksum(crc, llen);
68      llen >>= 8;
69    }
70  }
71
72  printf((toys.optflags & FLAG_H) ? "%x" : "%u",
73    (toys.optflags & FLAG_I) ? crc : ~crc);
74  printf(" %"PRIu64, llen2);
75  if (strcmp("-", name)) printf(" %s", name);
76  xputc('\n');
77}
78
79void cksum_main(void)
80{
81  crc_init(TT.crc_table, toys.optflags & FLAG_L);
82  loopfiles(toys.optargs, do_cksum);
83}
84