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/* cksum.c - produce crc32 checksum value for each input
*
* Copyright 2008 Rob Landley <rob@landley.net>
*
* See http://opengroup.org/onlinepubs/9699919799/utilities/cksum.html
USE_CKSUM(NEWTOY(cksum, "HIPLN", TOYFLAG_BIN))
config CKSUM
bool "cksum"
default y
help
usage: cksum [-IPLN] [file...]
For each file, output crc32 checksum value, length and name of file.
If no files listed, copy from stdin. Filename "-" is a synonym for stdin.
-H Hexadecimal checksum (defaults to decimal)
-L Little endian (defaults to big endian)
-P Pre-inversion
-I Skip post-inversion
-N Do not include length in CRC calculation
*/
#define FOR_cksum
#include "toys.h"
GLOBALS(
unsigned crc_table[256];
)
static unsigned cksum_be(unsigned crc, unsigned char c)
{
return (crc<<8)^TT.crc_table[(crc>>24)^c];
}
static unsigned cksum_le(unsigned crc, unsigned char c)
{
return TT.crc_table[(crc^c)&0xff] ^ (crc>>8);
}
static void do_cksum(int fd, char *name)
{
unsigned crc = (toys.optflags & FLAG_P) ? 0xffffffff : 0;
uint64_t llen = 0, llen2;
unsigned (*cksum)(unsigned crc, unsigned char c);
cksum = (toys.optflags & FLAG_L) ? cksum_le : cksum_be;
// CRC the data
for (;;) {
int len, i;
len = read(fd, toybuf, sizeof(toybuf));
if (len<0) perror_msg("%s", name);
if (len<1) break;
llen += len;
for (i=0; i<len; i++) crc=cksum(crc, toybuf[i]);
}
// CRC the length
llen2 = llen;
if (!(toys.optflags & FLAG_N)) {
while (llen) {
crc = cksum(crc, llen);
llen >>= 8;
}
}
printf((toys.optflags & FLAG_H) ? "%x" : "%u",
(toys.optflags & FLAG_I) ? crc : ~crc);
printf(" %"PRIu64, llen2);
if (strcmp("-", name)) printf(" %s", name);
xputc('\n');
}
void cksum_main(void)
{
crc_init(TT.crc_table, toys.optflags & FLAG_L);
loopfiles(toys.optargs, do_cksum);
}
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