select.txt

一个通讯程序源码

    43     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    44     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    45     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    46     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    47     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    48     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    49     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    4a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    4b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    4c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    4d     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    4e     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    4f     | 00 | 00 | 08 | 00 | 0 0 0 0 0 0 0 0 |              
    50     | 00 | 00 | 09 | 00 | 0 0 0 0 0 0 0 0 |              
    51     | 00 | 04 | 03 | 03 | 0 0 0 0 0 4 1 3 | _getdents    
    52     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    53     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    54     | 00 | 00 | 0a | 00 | 0 0 0 0 0 0 0 0 |              
    55     | 00 | 06 | 04 | 03 | 0 0 0 0 3 1 1 3 | _getmsg      
    56     | 00 | 06 | 04 | 03 | 0 0 0 0 3 1 1 3 | _putmsg      
    57     | 00 | 05 | 03 | 03 | 0 0 0 0 0 3 5 1 | _poll        
    58     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    59     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    5a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    5b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    5c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    5d     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    5e     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    5f     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    60     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    61     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    62     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    63     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       
    64     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys
    65     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    66     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    67     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    68     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    69     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    6a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    6b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    6c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    6d     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    6e     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    6f     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    70     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    71     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    72     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    73     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    74     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    75     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    76     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    77     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    78     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    79     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    7a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    7b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    7c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    7d     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    7e     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys      
    7f     | 00 | 05 | 05 | 0a | 0 0 0 0 0 0 0 0 | _clocal     

_v7sysent:

    00     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 |
    01     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 1 | _ftime   
    02     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys   
    03     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nullsys 
    04     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys   
    05     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys   
    06     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys   
    07     | 00 | 05 | 05 | 0a | 0 0 0 0 0 0 0 0 | _clocal  
    08     | 00 | 00 | 00 | 08 | 0 0 0 0 0 0 0 0 | _cxenix  
    09     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys   
    0a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys   
    0b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys   
    
_s3sysent:
    01     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 |
    02     | 00 | 06 | 04 | 03 | 0 0 0 0 3 3 1 1 | _statfs   
    03     | 00 | 05 | 04 | 03 | 0 0 0 0 3 3 1 3 | _fstatfs  
    04     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _setpgrp  
    05     | 00 | 00 | 00 | 08 | 0 0 0 0 0 0 0 0 | _cxenix   
    06     | 00 | 04 | 03 | 03 | 0 0 0 0 0 1 3 3 | _uadmin   
    07     | 00 | 00 | 00 | 09 | 0 0 0 0 0 0 0 0 | _utssys   
    08     | 00 | 03 | 03 | 03 | 0 0 0 0 0 3 3 3 | _fcntl    
    09     | 00 | 03 | 02 | 05 | 0 0 0 0 0 0 5 3 | _ulimit   
    0a     | 00 | 00 | 01 | 03 | 0 0 0 0 0 0 0 1 | _rmdir    
    0b     | 00 | 00 | 02 | 03 | 0 0 0 0 0 0 3 1 | _mkdir    
    0c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys    
    
_svidsysent:

    01     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 |
    02     | 00 | 06 | 04 | 03 | 0 0 0 0 3 3 1 1 | _statfs  
    03     | 00 | 05 | 04 | 03 | 0 0 0 0 3 3 1 3 | _fstatfs 
    04     | 00 | 00 | 01 | 03 | 0 0 0 0 0 0 0 3 | _setpgrp 
    05     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys   
    06     | 00 | 00 | 03 | 03 | 0 0 0 0 0 1 3 3 | _uadmin  
    07     | 00 | 00 | 00 | 09 | 0 0 0 0 0 0 0 0 | _utssys  
    08     | 00 | 00 | 03 | 03 | 0 0 0 0 0 3 3 3 | _fcntl   
    09     | 00 | 00 | 02 | 05 | 0 0 0 0 0 0 5 3 | _ulimit  
    0a     | 00 | 00 | 01 | 03 | 0 0 0 0 0 0 0 1 | _rmdir   
    0b     | 00 | 00 | 02 | 03 | 0 0 0 0 0 0 3 1 | _mkdir   
    0c     | 00 | 00 | 03 | 03 | 0 0 0 0 0 0 0 0 | _nosys   

_clentry: used for oem CLOCAL routines.  Empty on my system.

_cxentry: used for SCO added stuff.

    00     | 00 | 05 | 03 | 03 | 0 0 0 0 0 4 7 1 | _shutdown
    01     | 00 | 04 | 03 | 03 | 0 0 0 0 0 7 3 3 | _locking
    02     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 3 1 | _creatsem
    03     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 1 | _opensem
    04     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _sigsem
    05     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _waitsem
    06     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _nbwaitsem
    07     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _rdchk
    08     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 4 | _stkgrow
    09     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys
    0a     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 5 3 | _chsize
    0b     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 1 | _ftime
    0c     | 00 | 02 | 01 | 05 | 0 0 0 0 0 0 0 5 | _nap
    0d     | 00 | 05 | 04 | 01 | 0 0 0 0 3 4 3 1 | _sdget
    0e     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 7 | _sdfree
    0f     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 3 7 | _sdenter
    10     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 7 | _sdleave
    11     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 7 | _sdgetv
    12     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 3 7 | _sdwaitv
    13     | 00 | 05 | 03 | 01 | 0 0 0 0 0 7 5 3 | _brkctl
    14     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys
    15     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 1 3 | _nfs_sys
    16     | 00 | 04 | 03 | 03 | 0 0 0 0 0 1 3 3 | _msgctl
    17     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 3 5 | _msgget
    18     | 00 | 05 | 04 | 03 | 0 0 0 0 3 3 1 3 | _msgsnd
    19     | 06 | 07 | 05 | 03 | 0 0 0 3 5 3 1 3 | _msgrcv
    1a     | 00 | 05 | 04 | 03 | 0 0 0 0 7 3 4 3 | _semctl
    1b     | 00 | 04 | 03 | 03 | 0 0 0 0 0 3 3 5 | _semget
    1c     | 00 | 04 | 03 | 03 | 0 0 0 0 0 4 1 3 | _semop
    1d     | 00 | 04 | 03 | 03 | 0 0 0 0 0 1 3 3 | _shmctl
    1e     | 00 | 04 | 03 | 03 | 0 0 0 0 0 3 4 5 | _shmget
    1f     | 00 | 04 | 03 | 06 | 0 0 0 0 0 3 7 3 | _shmat
    20     | 00 | 04 | 03 | 03 | 0 0 0 0 0 1 3 3 | _proctl
    21     | 00 | 03 | 00 | 06 | 0 0 0 0 0 0 3 7 | _execseg
    22     | 00 | 02 | 00 | 03 | 0 0 0 0 0 0 0 7 | _unexecseg
    23     | 00 | 00 | 03 | 03 | 0 0 0 0 0 5 5 1 | _swapon
    24     | 00 | 09 | 05 | 03 | 0 0 0 1 1 1 1 3 | _select

I couldn't really figure out how uadmin() was accessed.  libc's
uadmin.o links in a routine that calls system call 0x37.  Hmmm...

The _cxentry is accessed by (documented in the programmer's reference
under System Calls) setting a bit in the system call number.  It seems
as though it actually shifts the system call number up half a word and
puts 0x28 in the low order halfword.

Now we see that select() exists as a cxenix function (number 0x24),

There is also poll(), putmsg(), and getmsg() -- streams stuff.
Since the tty device is not a streams device (actually it looks as if
the streams stuff has been nulled out -- look at the master file for
more information) it is highly unlikely that these routines will do
anything useful.  Infact, they don't.  Change the SYSNUM (and symbols)
in the example open.s above to their appropriate values to try out the
streams routines.

select.s looks something like:

; select
;
;
;

	title	select

	.386

SYSNUM	equ 	2428h

extrn	_errno:dword

public  _select

_TEXT	segment  dword use32 public 'CODE'
	assume   cs: _TEXT
_select	proc near
	mov	eax, SYSNUM		; Get system call number.

	;
	; I don't even pretend to understand masm syntax.  I tried
	; the following line (and variations) without any success.
	;

;	call    far 7:0			; Switch to kernel and call SYSNUM.

	;
	; Don't laugh, it works.
	;

	db 9ah
	dw 0,0
	dw 7

	jb	short _cerror		; below == error.

	xor	eax, eax		; zero return value (no error).
	ret				; done.

_cerror:
	mov	_errno, eax		; Save error code in _errno.
	mov	eax, -1			; Return -1 (as error).
	ret				; done.

_select	endp

_TEXT	ends

	end

There is a header file you'll need in <sys/select.h> which has some
information in it.

A Synopsis of the SCO XENIX implementation:

	#include <sys/select.h>

	nfds = select(width readfds, writefds, exceptfds, timeout)
	int width, *readfds, *writefds, *exceptfds;
	struct timeval *timeout;  /* timeval is a pointer to a structure */

I tested select() and found it to be half way implemented.  It seems
as if there must be some extra field in struct cdevsw <sys/conf.h>.

So, I guess I wait 'til 3.2.

Pax, Keith

Ps, FYI.

Pps, if I made a mistake in my description of system call handling on
SCO XENIX or what not, please correct me.

Ppps, `call far 7:0' seems really reasonable to me.
-- 
[e-mail]         Keith Gabryelski          ...!{ucsd, crash}!elgar!ag