NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/comp/std/c/3335

Text File | 1993-01-07 | 1.6 KB | 38 lines

Newsgroups: comp.std.c
Path: sparky!uunet!stanford.edu!nntp.Stanford.EDU!dkeisen
From: [e-mail] (Dave Eisen)
Subject: Re: Struct hack one last time (one last time)
Message-ID: <[e-mail]>
Sender: [e-mail] (Mr News)
Organization: Sequoia Peripherals, Inc.
Date: Thu, 7 Jan 93 22:12:07 GMT
Lines: 27


Deleting most of the back and forth here, you know where to
find it if you need it.

>|> >>An implementation is allowed to add padding to the end of a struct.
>|> >>Suppose that the implementation adds space to the end of each struct
>|> >>type where it encodes information used for run-time error checking.

>How should the poor compiler know WHERE to insert that information.  For malloc
>there might be special handling in the compiler, but consider a library
>memory-allocation routine of my own that returns void * and which does not
>impose a simple relationship between arguments and the size of the
>chunk of memory allocated!

This has nothing to do with malloc. The hypothetical compiler
could simply insert this error checking information whenever
it does a conversion from a (void *) to a (struct foo *). Again,
the basic question is still unresolved here: can a conversion
from one pointer type to another affect bytes other than those
where the pointer variable is stored?


--
Dave Eisen                               Sequoia Peripherals: [phone]
[e-mail]              Home:                [phone]
       There's something in my library to offend everybody.
          --- Washington Coalition Against Censorship