Listing 7: Copy to Swap area Program (file: cpsw.c)

/* Copyright (c) 1989, 1990 William Jolitz. All rights reserved.
 * Written by William Jolitz 7/89
 * Redistribution and use in source and binary forms are freely permitted
 * provided that the above copyright notice and attribution and date of work
 * and this paragraph are duplicated in all such forms.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 * This program copies a MSDOS file to BSD's idea of a swap partition,
 * known to be the second one in the disklabel. Typical use is to place
 * a TAR formatted file, obtained from a cross-host, onto swap. Then
 * BSD is booted with the boot program and the BSD tar utility is
 * used to extract the files being transferred within the TAR image,
 * hopefully before we need to page on the swap space. Again, this
 * program is rude in requiring one to adjust the manifest constant
 * denoting the cylinder on which the BSD root filesystem appears,
 * but this is another throw-away program to get the real work started.
 * Currently works with TURBO C 1.5 .
 */

#include <bios.h>

#include <alloc.h>
#include <fcntl.h>
#include <sys\stat.h>
#include "diskl.h"

/* Location of root partition. Adjust to suit given drive partition layout. */
#define   OFF_CYL   290   /* Cylinder offset of start of BSD root partition */

char *trkbuf;

#define BSIZE   512
struct label_blk {
   char bufr[LABELOFFSET];
   struct disklabel dl;
} lbl;

main(argc, argv) char *argv[]; {
   int fi, rem, cyl, head, tfrcnt;
   int bsize, ncyl, ntrack, nsect, off_cyl, maxcyl;

   if (argc != 2) {
      printf("usage: cpsw <file>\n");
      exit(1);
   }

   fi = open(argv[1], O_BINARY);
   if (fi < 0) {
      printf("Cannot open \"%s\" file to BSD swap\n",
         argv[1]);
      exit(1);
   }

   /* check for presence of disklabel */
   biosdisk(2, 0x80, 0, OFF_CYL, LABELSECTOR, 1, &lbl);
   if (lbl.dl.dk_magic != 0xabc) {
      printf("BSD root disk partition does not have a label!\n");
      exit(1);
   }

       /* Extract disk geometry and swap partition location from disk label. */
   bsize = lbl.dl.dk_secsize;
   nsect = lbl.dl.dk_nsectors;
   ntrack = lbl.dl.dk_ntracks;
   off_cyl = lbl.dl.dk_partition[1].cyloff;
   maxcyl = lbl.dl.dk_partition[1].cyloff +
      lbl.dl.dk_partition[1].nblocks / lbl.dl.dk_secpercyl;

   /* Allocate track buffer */
   trkbuf = malloc (nsect*bsize);

   printf("WARNING! About to overwrite disk (will loose previous\n");
   printf("contents). Are you certain of your use of this program?");
   if (getche() != 'y') exit(1);
   printf("\n");

   tfrcnt = head = 0;
   cyl = off_cyl;

   /* Transfer file to absolute disk section, a track at a time,
         because we're impatient. */
   while ((rem = read(fi, trkbuf, nsect*bsize)) == nsect*bsize) {
      biosdisk(3, 0x80, head, cyl, 1, nsect, trkbuf);
      if (++head == ntrack) {
         head = 0;
         if (++cyl > maxcyl) {
            printf("Overran swap partition!\n");
            exit(1);
         }
      }
      tfrcnt += nsect;
      printf("Amount transferred %5dK bytes\r",
         tfrcnt*BSIZE/1024);
   }

   /* Transfer any remainder leftover */
   if (rem > BSIZE-1) {
      biosdisk(3, 0x80, head, cyl, 1, rem/bsize, trkbuf);
      tfrcnt += rem/bsize;
      printf("Amount transferred %5dK bytes\n",
         tfrcnt*bsize/1024);
   }
   exit(0);
}