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Article #6357default DTAs and subshells...beware!
From: RENT THIS SPACE
Date: Wed, 30 Apr 1986 01:43
Date: Wed, 30 Apr 1986 01:43
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1297 bytes
I was using the default disk transfer address ($80 into the psp) for find first/find next, and running a subshell using the system() routine in the Microsoft C library. I discovered to my horror that when the system() returns, the dta for my program, as returned by the getdta dos call, had been changed to the dta of the subshell. Subsequent find first/find next calls write on the area where the subshell's dta lived. If your program grows (using the dos setblock call) into that area, it can be stomped on by find first/find next! Moral: always make (and set) your own dta, don't count on the default one. The surgeon general warns that DOS can be dangerous to your sanity. Jan Gray Looking Glass Software, Waterloo, Ont. (519) 884-7473
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site looking.UUCP Path: arc1-ca.pugleaf.net!utzoo!watmath!looking!jan From: jan@looking.UUCP (RENT THIS SPACE) Newsgroups: net.micro.pc Subject: default DTAs and subshells...beware! Message-ID: <530@looking.UUCP> Date: Tue, 29-Apr-86 21:43:10 EDT Article-I.D.: looking.530 Posted: Tue Apr 29 21:43:10 1986 Date-Received: Wed, 30-Apr-86 02:06:58 EDT Distribution: net Organization: Looking Glass Software Ltd. Waterloo, Ontario Lines: 16