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From: chris@wiley.UUCP (Chris Stassen)
Newsgroups: comp.unix.ultrix
Subject: getdiskbyname(3x) crashes after repeated calls.
Message-ID: <9434@felix.UUCP>
Date: Tue, 13-Oct-87 19:40:22 EDT
Article-I.D.: felix.9434
Posted: Tue Oct 13 19:40:22 1987
Date-Received: Fri, 16-Oct-87 04:58:37 EDT
Sender: zemon@felix.UUCP
Organization: The Lion's Den, Redondo Beach
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I don't know if this has been mentioned before...  we have found a bug in
Ultrix 2.0 libc source that causes getdiskbyname(3x) to crash on the eighth
invocation (or thereabouts).

[line 13 of /usr/src/lib/libc/vax/gen/disktab.c:]
< static char localbuf[100], *cp = localbuf;

[should be:]
> static char localbuf[100];
> char *cp = localbuf;

cp gets incremented as various strings are stored in localbuf (within
getdiskbyname()).  When cp runs off the end of localbuf (8th call), the
first value that gets wiped out is cp, and a core dump is caused.  The
problem is fixed by making cp "auto" (rather than "static"), which causes
the initialization (cp = localbuf) to be performed on every call.

[The strings stored in localbuf are pointed to from another static structure,
which is overwritten with every call to getdiskbyname(), so re-initializing
cp (and overwriting the strings from the last call) doesn't hurt.]

			-- Chris
-- 
"Nothing succeeds like a parakeet   | Chris Stassen
 with no teeth."  -- Benny Hill     | {trwrb|cit-vax}!wiley!chris