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Date: Sun, 12 Nov 2000 16:52:47 -0500
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From: DJ Delorie <dj AT delorie DOT com>
To: cygwin AT cygwin DOT com
In-reply-to: <20001112131900.A29324@redhat.com> (message from Christopher
	Faylor on Sun, 12 Nov 2000 13:19:00 -0500)
Subject: Re: Updated: Cygwin 1.1.5-7
References: <200011120904 DOT KAA19949 AT madrid DOT cdc DOT u-cergy DOT fr> <20001112131900 DOT A29324 AT redhat DOT com>


> >How can we read this `magic number' ?
> 
> Huh?  Use 'read()', I guess.  Is this a trick question?

It is if you don't know where or what to read.

Here are some details:

open the file in binary mode.

Read the first two characters.

If they are "MZ" or "ZM" then you have an MS-DOS executable.

One of the fields in the DOS header has a pointer to a *second* magic
number.  If this second magic number is "PE\0\0" then you have a
32-bit Windows executable.

If you need more information than that, look up Ralf Brown's interrupt
list, which details all the executable header types.

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