i've been able to read tarballs >2G and read individual files >2G in tarballs
with these changes. i've also incorporated the suggested cleanup.

one question, with tpfs, there's a cast to vlong:
	seek(tapefile, 512*(vlong)r->data+off, 0);
i cast to (int) because the size is only 3 bytes.
is there anything drasticlly wrong with this?

- erik

./fs.c
108c108
< 	r->blockno = 0;
---
> 	r->data = 0;
406,407c406,407
< //	if(off > 100*1024*1024)		/* sanity check */
< //		return "write too big";
---
> 	if(off > 100*1024*1024)		/* sanity check */
> 		return "write too big";
=====================================================
./32vfs.c
106c106
< doread(Ram *r, uvlong off, long cnt)
---
> doread(Ram *r, long off, long cnt)
109,117c109,112
< 	uvlong _bno;
< 	ulong bno;
< 	int i;
< 
< 	_bno = off/BLSIZE;
< 	off -= _bno*BLSIZE;
< 	bno = (ulong)bno;
< 	if (bno!=_bno)
< 		error("offset to large");
---
> 	int bno, i;
> 
> 	bno = off/BLSIZE;
> 	off -= bno*BLSIZE;
133c128
< dowrite(Ram *r, char *buf, uvlong off, long cnt)
---
> dowrite(Ram *r, char *buf, long off, long cnt)

=====================================================
./zipfs.c
33a34,41
> extern void populate(char *);
> extern void dotrunc(Ram *);
> extern void docreate(Ram *);
> extern char *doread(Ram *, long, long);
> extern void popdir(Ram *);
> extern void dowrite(Ram *, char *, long, long);
> extern int dopermw(Ram *);
> 
101c109
< doread(Ram *r, uvlong off, long cnt)
---
> doread(Ram *r, long off, long cnt)
113c121
< 	if (Bseek(bin, r->blockno, 0) < 0)
---
> 	if (Bseek(bin, (uvlong)r->data & 0x7fffffff, 0) < 0)
142c150
< 			if (r->blockno & 0x80000000 && MUNGE_CR){
---
> 			if ((uvlong)r->data & 0x80000000 && MUNGE_CR){
165c173
< dowrite(Ram *r, char *buf, uvlong off, long cnt)
---
> dowrite(Ram *r, char *buf, long off, long cnt)

=====================================================
./tapfs.c
95c95
< doread(Ram *r, uvlong off, long cnt)
---
> doread(Ram *r, long off, long cnt)
99c99
< 	seek(tapefile, 512*(int)r->blockno+off, 0);
---
> 	seek(tapefile, 512*(vlong)r->data+off, 0);
105c105
< dowrite(Ram *r, char *buf, uvlong off, long cnt)
---
> dowrite(Ram *r, char *buf, long off, long cnt)

=====================================================
./tarfs.c
38,39c38
< 	vlong blkno;
< 	long isabs, chksum, linkflg;
---
> 	long blkno, isabs, chksum, linkflg;
52c51
< 		f.blockno = blkno+1;
---
> 		f.addr = (void*)(blkno+1);
56c55
< 		f.size = strtoull(dblock.dbuf.size, 0, 8);
---
> 		f.size = strtoul(dblock.dbuf.size, 0, 8);
62c61
< 		||  strrchr(dblock.dbuf.name, '\0')[-1] == '/')
---
> 		||  strrchr(dblock.dbuf.name, '\0')[-1] == '/'){
63a63,64
> 			f.size = 0;
> 		}
69c70
< 			abort();
---
> 			exits("checksum");
100c101
< doread(Ram *r, uvlong off, long cnt)
---
> doread(Ram *r, long off, long cnt)
103c104
< 	seek(tapefile, (TBLOCK * r->blockno)+off, 0);
---
> 	seek(tapefile, (TBLOCK * (vlong)r->data)+off, 0);
117c118
< dowrite(Ram *r, char *buf, uvlong off, long cnt)
---
> dowrite(Ram *r, char *buf, long off, long cnt)
132,133c133,134
< 	int i;
< 	char *cp;
---
> 	register i;
> 	register char *cp;

=====================================================
./cpiofs.c
39c39
< uvlong	getoct(char*, int);
---
> int	getoct(char*, int);
79c79
< 		f.blockno = (offset+sizeof(struct header)+namesize);
---
> 		f.addr = (void*)(offset+sizeof(struct header)+namesize);
87c87
< uvlong
---
> int
90c90
< 	uvlong r;
---
> 	int r;
112c112
< doread(Ram *r, uvlong off, long cnt)
---
> doread(Ram *r, long off, long cnt)
115c115
< 	seek(tapefile, r->blockno+off, 0);
---
> 	seek(tapefile, (vlong)r->data+off, 0);
129c129
< dowrite(Ram *r, char *buf, uvlong off, long cnt)
---
> dowrite(Ram *r, char *buf, long off, long cnt)

=====================================================
./v6fs.c
107c107
< doread(Ram *r, uvlong off, long cnt)
---
> doread(Ram *r, long off, long cnt)
129c129
< dowrite(Ram *r, char *buf, uvlong off, long cnt)
---
> dowrite(Ram *r, char *buf, long off, long cnt)

=====================================================
./tpfs.c
20c20
< 	unsigned char	unused2[16];
---
> 	unsigned char	unused[16];
88c88
< doread(Ram *r, uvlong off, long cnt)
---
> doread(Ram *r, long off, long cnt)
92c92
< 	seek(tapefile, 512*(int)r->blockno+off, 0);
---
> 	seek(tapefile, 512*(vlong)r->data+off, 0);
98c98
< dowrite(Ram *r, char *buf, uvlong off, long cnt)
---
> dowrite(Ram *r, char *buf, long off, long cnt)

=====================================================
./util.c
96c96
< 			ent->blockno = fi.blockno;
---
> 			ent->data = fi.addr;
133c133
< 	ent->blockno = fi.blockno;
---
> 	ent->data = fi.addr;

=====================================================
./tapefs.h
41,45c41,42
< 	union {
< 		void	*data;
< 		uvlong	blockno;
< 	};
< 	uvlong	ndata;
---
> 	void	*data;
> 	long	ndata;
65,69c62,63
< 	union {
< 		void	*addr;
< 		uvlong	blockno;
< 	};
< 	uvlong	size;
---
> 	void	*addr;
> 	long	size;
89,90c83,84
< char	*doread(Ram*, uvlong, long);
< void	dowrite(Ram*, char*, uvlong, long);
---
> char	*doread(Ram*, long, long);
> void	dowrite(Ram*, char*, long, long);
92c86
< Idmap	*_getpass(char*);
---
> Idmap	*getpass(char*);

=====================================================
./v10fs.c
106c106
< doread(Ram *r, uvlong off, long cnt)
---
> doread(Ram *r, long off, long cnt)
109,113c109
< 	ulong bno;
< 	int i;
< 
< 	if (off>0xffffffff)
< 		error("offset too large");
---
> 	int bno, i;
132c128
< dowrite(Ram *r, char *buf, uvlong off, long cnt)
---
> dowrite(Ram *r, char *buf, long off, long cnt)

=====================================================