/* hdinfo.c 
 *
 * 6/2/93, gt8134b@prism.gatech.edu, Robert Sanders
 *
 * print the partition information for a given disk file (device or image).
 * Print the byte offset from the beginning of the file to the
 * start of the partition, which is useful for mounting the loop
 * device (i.e. mounting a file), which is why I wrote this.
 *
 * It's made slightly more complicated by the header prepended to
 * dosemu hdimage files.  The length of the header is kept in byte
 * 19 of the header as an unsigned long.  The header is guaranteed
 * to always be at least 128 bytes long, but never more than 512.
 *
 * BUGS: on my disk, the second logical partition of the extended partition
 *   is said to start 1 sector earlier than it actually does (and therefore
 *   512 bytes earlier).
 */

#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <stdio.h>
#include <linux/genhd.h>

#define SECTOR_SIZE	512
#define EXT_MAGIC	5	/* sys_ind for an extended partition */

int fd = -1;
char *decfmt = "%sSector=%-6d   Offset=%-10d   Type=0x%02x%s\n";
char *hexfmt = "%sSector=0x%-6x   Offset=0x%-8x   Type=0x%02x%s\n";
char *fmtstring;


void
usage(void)
{
  fprintf(stderr, "usage: hdinfo [-h] <image file or disk device>\n");
}


void
print_part(struct partition *part, size_t offset, int sect_off, int ext)
{
  char *indent = ext ? "       ["  :  "";
  char *exdent = ext ?        "]"  :  "";
  int i;

  if (part->sys_ind)
    printf(fmtstring, indent,
	   part->start_sect + sect_off, 
	   (part->start_sect + sect_off) * SECTOR_SIZE + offset,
	   part->sys_ind, exdent);

  if (part->sys_ind == EXT_MAGIC && !ext)
    {
      char ext[512];

      lseek(fd, part->start_sect * SECTOR_SIZE + offset, SEEK_SET);
      if (read(fd, ext, 512) < 512)
	{
	  perror("hdinfo: Could not read sector");
	  exit(1);
	}

      for (i=0; i<4; i++)
	{
	  print_part((struct partition *) (ext + 0x1be + i*16), offset, 
		     part->start_sect, 1);
	}
    }
}


int
main(int argc, char **argv)
{
  int i, hdimage_off=0;
  char *filename;
  char mbr[1024], ext[512];
  struct partition *part;

  fmtstring = decfmt;

  if (argc == 3)
    {
      if ( !strcmp(argv[1], "-h"))
	fmtstring = hexfmt;
      else
	{
	  usage();
	  exit(1);
	}
      filename = argv[2];
    }
  else if (argc == 2)
    filename = argv[1];
  else
    {
      usage();
      exit(1);
    }

  if ( (fd = open(filename, O_RDONLY)) < 0)
    {
      perror("hdinfo: Cannot open file");
      exit(1);
    }

  if (read(fd, mbr, 1024) < 1024)
    {
      perror("hdinfo: Could not read MBR\n");
      exit(1);
    }

  if (! strncmp(mbr, "DOSEMU", 6))
      hdimage_off = *(u_long *)(mbr + 19);
  else hdimage_off = 0;

  printf("Partition info for %s %s\n=================================================\n", 
	 filename, hdimage_off ? "(a DOSEMU 0.49 hdimage file)" : "");

  for (i=0; i<4; i++)
      print_part( (struct partition *) (mbr + 0x1be + hdimage_off + i*16), 
		 hdimage_off, 0, 0 );
}