sbase

suckless unix tools
git clone git://git.2f30.org/sbase.git
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commit f3188246d860c858df22d3d734e7871b8919ead0
parent 146cca114e365d89780e7bcd88b8cb83eb561dcf
Author: Connor Lane Smith <cls@lubutu.com>
Date:   Mon May 14 21:30:02 +0100

cksum: ARGBEGIN, no buffering
Diffstat:
cksum.c | 50++++++++++++++++++++++++++++++--------------------
1 file changed, 30 insertions(+), 20 deletions(-)
diff --git a/cksum.c b/cksum.c @@ -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; + + ARGBEGIN { + default: + USAGE(); + } ARGEND; - 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); + 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');