minix/commands/sum/sum.c

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2005-04-21 16:53:53 +02:00
/* sum - checksum a file Author: Martin C. Atkins */
/*
* This program was written by:
* Martin C. Atkins,
* University of York,
* Heslington,
* York. Y01 5DD
* England
* and is released into the public domain, on the condition
* that this comment is always included without alteration.
*/
#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <minix/minlib.h>
#include <stdio.h>
#define BUFFER_SIZE (512)
int rc = 0;
char *defargv[] = {"-", 0};
int main(int argc, char **argv);
void error(char *s, char *f);
void sum(int fd, char *fname);
void putd(int number, int fw, int zeros);
2005-04-21 16:53:53 +02:00
int main(argc, argv)
int argc;
char *argv[];
{
register int fd;
if (*++argv == 0) argv = defargv;
for (; *argv; argv++) {
if (argv[0][0] == '-' && argv[0][1] == '\0')
fd = 0;
else
fd = open(*argv, O_RDONLY);
if (fd == -1) {
error("can't open ", *argv);
rc = 1;
continue;
}
sum(fd, (argc > 2) ? *argv : (char *) 0);
if (fd != 0) close(fd);
}
return(rc);
}
void error(s, f)
char *s, *f;
{
std_err("sum: ");
std_err(s);
if (f) std_err(f);
std_err("\n");
}
void sum(fd, fname)
int fd;
char *fname;
{
char buf[BUFFER_SIZE];
register int i, n;
long size = 0;
unsigned crc = 0;
unsigned tmp, blks;
while ((n = read(fd, buf, BUFFER_SIZE)) > 0) {
for (i = 0; i < n; i++) {
crc = (crc >> 1) + ((crc & 1) ? 0x8000 : 0);
tmp = buf[i] & 0377;
crc += tmp;
crc &= 0xffff;
size++;
}
}
if (n < 0) {
if (fname)
error("read error on ", fname);
else
error("read error", (char *) 0);
rc = 1;
return;
}
putd(crc, 5, 1);
blks = (size + (long) BUFFER_SIZE - 1L) / (long) BUFFER_SIZE;
putd(blks, 6, 0);
if (fname) printf(" %s", fname);
printf("\n");
}
void putd(number, fw, zeros)
int number, fw, zeros;
{
/* Put a decimal number, in a field width, to stdout. */
char buf[10];
int n;
unsigned num;
num = (unsigned) number;
for (n = 0; n < fw; n++) {
if (num || n == 0) {
buf[fw - n - 1] = '0' + num % 10;
num /= 10;
} else
buf[fw - n - 1] = zeros ? '0' : ' ';
}
buf[fw] = 0;
printf("%s", buf);
}