122 lines
2.1 KiB
C
122 lines
2.1 KiB
C
/* sum - checksum a file Author: Martin C. Atkins */
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/*
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* This program was written by:
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* Martin C. Atkins,
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* University of York,
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* Heslington,
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* York. Y01 5DD
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* England
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* and is released into the public domain, on the condition
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* that this comment is always included without alteration.
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*/
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#include <sys/types.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <minix/minlib.h>
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#include <stdio.h>
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#define BUFFER_SIZE (512)
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int rc = 0;
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char *defargv[] = {"-", 0};
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int main(int argc, char **argv);
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void error(char *s, char *f);
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void sum(int fd, char *fname);
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void putd(int number, int fw, int zeros);
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int main(argc, argv)
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int argc;
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char *argv[];
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{
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register int fd;
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if (*++argv == 0) argv = defargv;
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for (; *argv; argv++) {
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if (argv[0][0] == '-' && argv[0][1] == '\0')
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fd = 0;
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else
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fd = open(*argv, O_RDONLY);
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if (fd == -1) {
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error("can't open ", *argv);
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rc = 1;
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continue;
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}
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sum(fd, (argc > 2) ? *argv : (char *) 0);
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if (fd != 0) close(fd);
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}
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return(rc);
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}
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void error(s, f)
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char *s, *f;
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{
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std_err("sum: ");
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std_err(s);
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if (f) std_err(f);
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std_err("\n");
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}
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void sum(fd, fname)
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int fd;
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char *fname;
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{
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char buf[BUFFER_SIZE];
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register int i, n;
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long size = 0;
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unsigned crc = 0;
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unsigned tmp, blks;
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while ((n = read(fd, buf, BUFFER_SIZE)) > 0) {
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for (i = 0; i < n; i++) {
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crc = (crc >> 1) + ((crc & 1) ? 0x8000 : 0);
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tmp = buf[i] & 0377;
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crc += tmp;
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crc &= 0xffff;
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size++;
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}
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}
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if (n < 0) {
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if (fname)
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error("read error on ", fname);
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else
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error("read error", (char *) 0);
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rc = 1;
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return;
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}
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putd(crc, 5, 1);
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blks = (size + (long) BUFFER_SIZE - 1L) / (long) BUFFER_SIZE;
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putd(blks, 6, 0);
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if (fname) printf(" %s", fname);
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printf("\n");
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}
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void putd(number, fw, zeros)
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int number, fw, zeros;
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{
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/* Put a decimal number, in a field width, to stdout. */
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char buf[10];
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int n;
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unsigned num;
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num = (unsigned) number;
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for (n = 0; n < fw; n++) {
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if (num || n == 0) {
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buf[fw - n - 1] = '0' + num % 10;
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num /= 10;
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} else
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buf[fw - n - 1] = zeros ? '0' : ' ';
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}
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buf[fw] = 0;
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printf("%s", buf);
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}
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