realloc() and POSIX threads

From	Doug Weiman <no@nyet.net>
Newsgroups	comp.lang.c
Subject	realloc() and POSIX threads
Date	2019-09-27 21:29 +0000
Organization	albasani.net
Message-ID	<qmlv0b$bt0$1@news.albasani.net> (permalink)

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	My question may not belong in this group - my apologies if that 
is the case.

	I have some application that allocates memory with malloc(), and 
then uses the resulting pointer as an argument to a POSIX thread that is 
launched immediately after. While the thread is doing its thing with the 
memory pointed to by this pointer, the application augments that pointer 
with realloc().

	My understanding is that realloc() is no guaranteed to keep the 
original pointer. That is, if necessary, realloc() will obtain a 
different pointer to a memory region with enough space, and copy here the 
contents of the memory region pointed to by the original pointer, finally 
returning thee new pointer to the caller.

	This is, of course, potentially disastrous to the thread above, 
which is still operating on a memory area now deallocated. I mean, you 
may be lucky and the area will still be usable, but sooner or later the 
whole thing will blow up in yor face.

	Is there a way to implement the scenario above (memory 
allocation, thread creation, memory reallocation) safely, so that the 
thread can be guaranteed to still have access to valid memory? One could 
use thread mutexes, but that would effectively serialize things.

	Any other suggestions? Or is this the kind of thing that one just 
ought not to do, period? For a number of reasons, getting the thread 
itself to allocate the memory is not an option.

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realloc() and POSIX threads Doug Weiman <no@nyet.net> - 2019-09-27 21:29 +0000
  Re: realloc() and POSIX threads Robert Wessel <robertwessel2@yahoo.com> - 2019-09-27 17:11 -0500
  Re: realloc() and POSIX threads Florian Weimer <fw@deneb.enyo.de> - 2019-09-28 09:27 +0200
  Re: realloc() and POSIX threads Melzzzzz <Melzzzzz@zzzzz.com> - 2019-09-28 08:42 +0000
  Re: realloc() and POSIX threads "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-28 03:53 -0700
    Re: realloc() and POSIX threads "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-28 03:55 -0700
  Re: realloc() and POSIX threads Richard Damon <Richard@Damon-Family.org> - 2019-09-28 08:29 -0400
    Re: realloc() and POSIX threads Doug Weiman <no@nyet.net> - 2019-09-28 15:06 +0000
    Re: realloc() and POSIX threads "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-28 15:19 -0700
      Re: realloc() and POSIX threads "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-09-28 15:23 -0700

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