xenix redux (or, how to bring back a dead xenix pc)

[Brad Parker]

Cameron Kaiser wrote:
>> I then put the resulting disk image on another linux box and wrote a
>> tiny C program to search for valid sysv super blocks.
>
>Mind posting the source?

no problem.  it was just a quick hack.

--- cut here ---

#include <stdio.h>
#include <fcntl.h>

#define __packed2__  __attribute__ ((packed, aligned(2)))

typedef unsigned short u16;
typedef unsigned int u32;
typedef short s16;
typedef int s32;

typedef u16 sysv_ino_t;
typedef u32 sysv_zone_t;

/* Xenix super-block data on disk */
#define XENIX_NICINOD	100	/* number of inode cache entries */
#define XENIX_NICFREE	100	/* number of free block list chunk entries */
struct xenix_super_block {
	u16		s_isize; /* index of first data zone */
	u32		s_fsize __packed2__; /* total number of zones of this fs */
	/* the start of the free block list: */
	u16		s_nfree;	/* number of free blocks in s_free, <= XENIX_NICFREE */
	u32		s_free[XENIX_NICFREE]; /* first free block list chunk */
	/* the cache of free inodes: */
	u16		s_ninode; /* number of free inodes in s_inode, <= XENIX_NICINOD */
	sysv_ino_t	s_inode[XENIX_NICINOD]; /* some free inodes */
	/* locks, not used by Linux: */
	char		s_flock;	/* lock during free block list manipulation */
	char		s_ilock;	/* lock during inode cache manipulation */
	char		s_fmod;		/* super-block modified flag */
	char		s_ronly;	/* flag whether fs is mounted read-only */
	u32		s_time __packed2__; /* time of last super block update */
	u32		s_tfree __packed2__; /* total number of free zones */
	u16		s_tinode;	/* total number of free inodes */
	s16		s_dinfo[4];	/* device information ?? */
	char		s_fname[6];	/* file system volume name */
	char		s_fpack[6];	/* file system pack name */
	char		s_clean;	/* set to 0x46 when filesystem is properly unmounted */
	char		s_fill[371];
	s32		s_magic;	/* version of file system */
	s32		s_type;		/* type of file system: 1 for 512 byte blocks
								2 for 1024 byte blocks
								3 for 2048 byte blocks */
								
};

char buffer[4096];

main()
{
	int fd, ret;
	struct xenix_super_block *sb;
	int offset;

	fd = open("d1", O_RDONLY);
	sb = (struct xenix_super_block *)buffer;
	printf("size %d\n", sizeof(struct xenix_super_block));
	//printf("offset %d\n", ((char *)&sb->s_magic) - buffer);

	offset = 0;
	while (1) {
		ret = read(fd, buffer, 1024);
		if (ret != 1024)
			break;

		if (sb->s_magic == 0x002b5544 &&
		    (sb->s_type >= 1 && sb->s_type <= 3))
		{
			printf("offset %d 0x%x\n", offset, offset);
			printf("block %d\n", (offset-1024) / 512);
			printf("s_magic %08x\n", sb->s_magic);
			printf("s_type %08x\n", sb->s_type);
			printf("s_nfree %04x\n", sb->s_nfree);

		}
		offset += 1024;
	}


}