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Message-ID: <3AB60CEC.7FB88267@cs.technion.ac.il>
Date: Mon, 19 Mar 2001 15:43:08 +0200
From: Claus Wagner <cwagner AT cs DOT Technion DOT AC DOT IL>
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To: cygwin AT cygwin DOT com
Subject: ?mmap?
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Hi!

This e-mail concerns the current "mmap" implementation.

When I map the same piece of a file twice into the virtual address space (using
*mmap*)
the second call returns the same address as the first call has returned.

There are some cases, which make a multiple mapping of the same piece of a file
reasonable.

For example setting different protection attributes for two regions of one file:

....
ptr1 = mmap(fd,...,offset);
ptr2 = mmap(fd,...,offset);
....
mprotect(ptr1,PROT_READ,PAGE_SIZE);
mprotect(ptr2,PROT_WRITE|PROT_READ,PAGE_SIZE);
.....


Anyway, I don't think, that the semantic of mmap should be like it is right now
in your implementaion.

Regards Claus Wagner.

ps: ... or should I read the POSIX standard :-)


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