ardai@sybil.UUCP (Mike Ardai) (07/31/88)
I just noticed some strangeness on our 8550. It has been up for
30 days, and the lat terminal numbers have just topped 999. It
seems that 'show users' or something is using an 8-byte buffer
to hold the terminal name and has just overflowed. I hope there
is nothing important in the next byte :-} Does anyone know if this
is just an ignorable nuisance, or is it a potential problem?
/mike
VAX/VMS Interactive Users
30-JUL-1988 10:43:14.44
Total number of interactive users = 3
Username Process Name PID Terminal
ARDAI Ardai 20407260 LTA1009 LTA1009:
ZELLER ZELLER985 20406522 LTA985:
ZELLER ZELLER986 20406525 LTA986:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Michael L. Ardai Teradyne DATA Group
Usenet: ...!sun!sequent!sybil!ardai
USnail: 179 Lincoln St. Boston MA 02111
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#include <disclaimer.h>MNK@DRACO.HAC.COM (Michael N. Kimura) (08/09/88)
> > From: Mike Ardai <sequent!sybil!ardai@DECWRL.DEC.COM> > > Subject: Terminal name length problems > > To: John Hascall <GA.JPH@ISUMVS> > > > > I just noticed some strangeness on our 8550. It has been up for > > 30 days, and the lat terminal numbers have just topped 999. It > > seems that 'show users' or something is using an 8-byte buffer > > to hold the terminal name and has just overflowed. I hope there > > is nothing important in the next byte :-} Does anyone know if this > > is just an ignorable nuisance, or is it a potential problem? > > > > /mike > > VAX/VMS Interactive Users > > 30-JUL-1988 10:43:14.44 > > Total number of interactive users = 3 > > > > Username Process Name PID Terminal > > ARDAI Ardai 20407260 LTA1009 LTA1009: > > ZELLER ZELLER985 20406522 LTA985: > > ZELLER ZELLER986 20406525 LTA986: > > > The same thing happens here, it seems that the show users buffer > is too small, hence the truncation. Also it looks at the last > character of the terminal name an if it is not at colon, it thinks > that it is a virtual terminal and so it looks for and displays the > "real live physical terminal" as well.... As it turns out SHOW USERS displays your terminal name from the PCB which is at offset PCB$T_TERMINAL and is a counted string (i.e. first byte is the length of the string) PCB$S_TERMINAL (8) bytes long. Therefore VMS can only hold a 7 byte terminal name in the PCB. You can verify that by calling $GETJPI with an item of JPI$_TERMINAL which will return PCB$T_TERMINAL. $ write sys$output f$getjpi("20407260","TERMINAL") LTA1009 Also, if the physical terminal name returned from $GETDVI (DVI$_TT_PHYDEVNAM) is not identical to the terminal name returned from $GETJPI (JPI$_TERMINAL) then the physical terminal name is also displayed. Usually this will be the case for a virtual terminal, but this is also the case when the PCB$T_TERMINAL name has had the colon truncated off and doesn't match the full name with the colon returned by $GETDVI --------------------------------------------------------------------------- Michael Kimura Internet: mnk%draco@hac2arpa.hac.com BITnet: mnk@draco.hac.com Telephone: (213) 615-9775 US Mail: Hughes Aircraft Company (RSG) P.O. Box 92426 MS: R2/A159 Los Angeles, CA 90009 ---------------------------------------------------------------------------