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From: russotto@eng.umd.edu (Matthew T. Russotto)
Newsgroups: comp.sys.mac.programmer,comp.sys.mac
Subject: Re: Finding the current position of an open file--again
Message-ID: <1990Mar8.175722.18852@eng.umd.edu>
Date: 8 Mar 90 17:57:22 GMT
References: <5743.25f51321@george.uh.edu> <5753.25f634f1@george.uh.edu>
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In article <5753.25f634f1@george.uh.edu> mike@george.uh.edu (Mike Frederick) writes:

>I am attempting to learn exactly how a program (for which I do not have source)
>works.  I have trapped a READ (xA002), and I can see the paramBlock with the
>ioRefNum in it.  Using only MacBugs, how can I get to the file mark?  I see
>something called a File Control Block which is kept in memory for each open
>file, and it a field called fcbCrPs which is described as "mark".  Is this
>what I want, and how do I get to the correct FCB from the paramBlock?

Try the 'file' dcmd that comes with the later (post- 6.0) MacsBugs' It will
tell you all you want to know.  And if it doesnt, use the 'dm' command
with the template for FCBs on the address the 'file' command gives you.
The new MacsBug is GREAT!
--
Matthew T. Russotto	russotto@eng.umd.edu	russotto@wam.umd.edu
][, ][+, ///, ///+, //e, //c, IIGS, //c+ --- Any questions?