commands/sum/sum.c

   1 /* sum - checksum a file                Author: Martin C. Atkins */
   2
   3 /*
   4  *      This program was written by:
   5  *              Martin C. Atkins,
   6  *              University of York,
   7  *              Heslington,
   8  *              York. Y01 5DD
   9  *              England
  10  *      and is released into the public domain, on the condition
  11  *      that this comment is always included without alteration.
  12  */
  13
  14 #include <sys/types.h>
  15 #include <fcntl.h>
  16 #include <stdlib.h>
  17 #include <unistd.h>
  18 #include <minix/minlib.h>
  19 #include <stdio.h>
  20
  21 #define BUFFER_SIZE (512)
  22
  23 int rc = 0;
  24
  25 char *defargv[] = {"-", 0};
  26
  27 _PROTOTYPE(int main, (int argc, char **argv));
  28 _PROTOTYPE(void error, (char *s, char *f));
  29 _PROTOTYPE(void sum, (int fd, char *fname));
  30 _PROTOTYPE(void putd, (int number, int fw, int zeros));
  31
  32 int main(argc, argv)
  33 int argc;
  34 char *argv[];
  35 {
  36   register int fd;
  37
  38   if (*++argv == 0) argv = defargv;
  39   for (; *argv; argv++) {
  40         if (argv[0][0] == '-' && argv[0][1] == '\0')
  41                 fd = 0;
  42         else
  43                 fd = open(*argv, O_RDONLY);
  44
  45         if (fd == -1) {
  46                 error("can't open ", *argv);
  47                 rc = 1;
  48                 continue;
  49         }
  50         sum(fd, (argc > 2) ? *argv : (char *) 0);
  51         if (fd != 0) close(fd);
  52   }
  53   return(rc);
  54 }
  55
  56 void error(s, f)
  57 char *s, *f;
  58 {
  59
  60   std_err("sum: ");
  61   std_err(s);
  62
  63   if (f) std_err(f);
  64   std_err("\n");
  65 }
  66
  67 void sum(fd, fname)
  68 int fd;
  69 char *fname;
  70 {
  71   char buf[BUFFER_SIZE];
  72   register int i, n;
  73   long size = 0;
  74   unsigned crc = 0;
  75   unsigned tmp, blks;
  76
  77   while ((n = read(fd, buf, BUFFER_SIZE)) > 0) {
  78         for (i = 0; i < n; i++) {
  79                 crc = (crc >> 1) + ((crc & 1) ? 0x8000 : 0);
  80                 tmp = buf[i] & 0377;
  81                 crc += tmp;
  82                 crc &= 0xffff;
  83                 size++;
  84         }
  85   }
  86
  87   if (n < 0) {
  88         if (fname)
  89                 error("read error on ", fname);
  90         else
  91                 error("read error", (char *) 0);
  92         rc = 1;
  93         return;
  94   }
  95   putd(crc, 5, 1);
  96   blks = (size + (long) BUFFER_SIZE - 1L) / (long) BUFFER_SIZE;
  97   putd(blks, 6, 0);
  98   if (fname) printf(" %s", fname);
  99   printf("\n");
 100 }
 101
 102 void putd(number, fw, zeros)
 103 int number, fw, zeros;
 104 {
 105 /* Put a decimal number, in a field width, to stdout. */
 106
 107   char buf[10];
 108   int n;
 109   unsigned num;
 110
 111   num = (unsigned) number;
 112   for (n = 0; n < fw; n++) {
 113         if (num || n == 0) {
 114                 buf[fw - n - 1] = '0' + num % 10;
 115                 num /= 10;
 116         } else
 117                 buf[fw - n - 1] = zeros ? '0' : ' ';
 118   }
 119   buf[fw] = 0;
 120   printf("%s", buf);
 121 }