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/* vi: set sw=4 ts=4:
*
* cksum.c - produce crc32 checksum value for each input
*
* Copyright 2008 Rob Landley <rob@landley.net>
*
* See http://www.opengroup.org/onlinepubs/009695399/utilities/cksum.html
USE_CKSUM(NEWTOY(cksum, "F", TOYFLAG_BIN))
config CKSUM
bool "cksum"
default y
help
usage: cksum [-F] [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.
-F Start with 0xffffffff instead of 0.
*/
#include "toys.h"
DEFINE_GLOBALS(
unsigned crc_table[256];
)
#define TT this.cksum
static unsigned cksum(unsigned crc, unsigned char c)
{
return (crc<<8)^TT.crc_table[(crc>>24)^c];
}
static void do_cksum(int fd, char *name)
{
unsigned crc = toys.optflags ? 0xffffffff : 0;
uint64_t llen = 0, llen2;
// CRC the data
for (;;) {
int len, i;
len = read(fd, toybuf, sizeof(toybuf));
if (len<0) {
perror_msg("%s",name);
toys.exitval = EXIT_FAILURE;
}
if (len<1) break;
llen += len;
for (i=0; i<len; i++) crc=cksum(crc, toybuf[i]);
}
// CRC the length
llen2 = llen;
while (llen) {
crc = cksum(crc, llen);
llen >>= 8;
}
printf("%u %"PRIu64, ~crc, llen2);
if (strcmp("-", name)) printf(" %s", name);
xputc('\n');
}
void cksum_main(void)
{
crc_init(TT.crc_table);
loopfiles(toys.optargs, do_cksum);
}
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