[Linux-abi-devel] patch regarding xenix programs

[<jo...@hy...>]

Hi,

while testing some old Xenix programs, I found two bugs in linux-abi. The
solution in both cases was in the iBCS code :-| .

case_1: these old programs tend to read a directory with read(). 
     a) Xenix doesn't allow filenames longer than 14 characters. So longer
	    Linux entries have to be skipped (this was missing).
	 b) the long Linux inodes have to be folded to short inodes. This was
	    wrong, some type casts were missing.
	This is in abi/svr4/misc.c
	
case_2: For old V3 programs (linux "file" says pre-SysV) Xenix allows to get 
		a read_lock for files opened with access mode WRONLY, Linux doesn't. 
		It looks to me as if this "feature" is part of the bug compattibility
		of newer Xenix versions for those old V3 programs. I imagine that in
		the dark ages of Unix there was a Xenix Version with a rather broken
		implementation of locking. Read locks were handled as if they were
		write locks and so on. 
		Parts of this "bug compattibility" are handled in user land: x286emul.
		This one can't. So xnx_locking() has to set the access mode for the 
		file temporarily to RDWR while getting the lock. NOTE: this will
		change the behaviour for V5 programs: they may get a lock in a 
		situation where Xenix doesn't allow the lock. To overcome this, we
		probably have to invent an new personality. 
		This is in abi/cxenix/misc.c .
		
Please include this patch (or a better solution) in future linux-abi versions.

Christoph, are you still listening? 

Joerg
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Joerg Ahrens                                              _/           
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