RE: Bug in make-3.81: variable_buffer moves out from under buffer

[Martin Dorey]

In the original makefile, does the long rule really not contain any variables or involve any $(eval) trickery?

 

-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of David Wuertele
Sent: Tuesday, January 20, 2009 13:44
To: address@hidden
Subject: Re: Bug in make-3.81: variable_buffer moves out from under buffer

 

Martin Dorey <mdorey <at> bluearc.com> writes:

 

> And it looks like there are several other instances of it too.

 

That's what I was afraid of.  I looked at the other places where xrealloc

could get called, but I couldn't find any that referenced the original buffer

address after the xrealloc.  I suspected that I might have missed some ---

xrealloc is used really heavily.

 

> >> What I am looking for is some help writing a makefile that

> >> is simple enough to post in a bug report.

>

> I had a few goes but it looks like the variable_buffer is always already

> big enough by the time it gets here.  Can you tell us what rule it falls

> over on for you or what trickery might be associated with that rule?  Is

> there, for example, re-reading of makefiles going on, or $(eval) magic?

 

It is a static pattern rule, during the following function:

 

main() -> snap_deps() -> expand_deps()

 

This function calls patsubst_expand() on the rule target, and when

patsubst_expand returns, the original buffer contents have moved.

 

I tried reducing my makefile to just the two rules that trigger the bug (one

that sets variable_buffer to the default size of 200, and one that busts beyond

it), but somehow I can't get the variable_buffer to stay at 200 before it gets

to the static pattern rule.  Here's what I expected the reduced makefile to

look like:

 

a1: a%: b%; @echo trash

 

a2222222222222222222222222222222222222222222222222222222222222222222222222222\

2222222222222222222222:

a22222222222222222222222222222222222222222%:

c%22222222222222222222222222222222222222222222; @echo trash

 

But somehow the variable_buffer is already big enough when it gets to the

long rule.

 

Dave

 

 

 

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