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cksum: ARGBEGIN, no buffering

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This commit is contained in:
Connor Lane Smith 2012-05-14 21:30:02 +01:00
parent 146cca114e
commit f3188246d8
1 changed files with 30 additions and 20 deletions
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50
cksum.c
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@ -1,10 +1,13 @@
/* See LICENSE file for copyright and license details. */
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "util.h"
static void cksum(FILE *, const char *);
#define USAGE() usage("[files...]")
static void cksum(int, const char *);
static const unsigned long crctab[] = { 0x00000000,
0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
@ -63,35 +66,42 @@ static const unsigned long crctab[] = { 0x00000000,
int
main(int argc, char *argv[])
{
FILE *fp;
int i, fd;
if(getopt(argc, argv, "") != -1)
exit(EXIT_FAILURE);
if(optind == argc)
cksum(stdin, NULL);
else for(; optind < argc; optind++) {
if(!(fp = fopen(argv[optind], "r")))
eprintf("fopen %s:", argv[optind]);
cksum(fp, argv[optind]);
fclose(fp);
ARGBEGIN {
default:
USAGE();
} ARGEND;
if(argc == 0)
cksum(STDIN_FILENO, NULL);
else for(i = 0; i < argc; i++) {
if((fd = open(argv[i], O_RDONLY)) == -1)
eprintf("open %s:", argv[i]);
cksum(fd, argv[i]);
close(fd);
}
return EXIT_SUCCESS;
}
void
cksum(FILE *fp, const char *s)
cksum(int fd, const char *s)
{
int c;
unsigned long i, n, ck = 0;
unsigned char buf[BUFSIZ];
unsigned int ck = 0;
size_t len;
int i, n;
for(n = 0; (c = getc(fp)) != EOF; n++)
ck = (ck << 8) ^ crctab[(ck >> 24) ^ c];
for(i = n; i > 0; i >>= 8)
ck = (ck << 8) ^ crctab[(ck >> 24) ^ (i & 0377)];
if(ferror(fp))
for(len = 0; (n = read(fd, buf, sizeof buf)) > 0; len += n)
for(i = 0; i < n; i++)
ck = (ck << 8) ^ crctab[(ck >> 24) ^ buf[i]];
if(n < 0)
eprintf("%s: read error:", s ? s : "<stdin>");
printf("%lu %lu", ~ck, n);
for(i = len; i > 0; i >>= 8)
ck = (ck << 8) ^ crctab[(ck >> 24) ^ (i & 0xFF)];
printf("%u %lu", ~ck, len);
if(s != NULL)
printf(" %s", s);
putchar('\n');