Re: [PATCH] newlib: Fix memory leak regarding gdtoa-based _ldtoa_r().

[Takashi Yano <takashi.yano@nifty.ne.jp>]

On Tue, 1 Aug 2023 14:35:54 +0200
Corinna Vinschen wrote:
> Hi Takashi,
> 
> On Aug  1 17:57, Takashi Yano wrote:
> > After the commit a4705d387f78, printf() for floating-point values
> > causes a memory leak. The legacy _ldtoa_r() assumed the char pointer
> > returned will be free'ed by Bfree(). However, gdtoa-based _ldtoa_r()
> > returns the pointer returned by gdtoa() which should be free'ed by
> > freedtoa(). Due to this issue, the caller of _ldtoa_r() fails to free
> > the allocated char buffer. This is the cause of the said memory leak.
> > https://cygwin.com/pipermail/cygwin/2023-July/254054.html
> > 
> > With this patch, a new buffer is allocated using Balloc() and the
> > buffer returned by gdtoa() is copied into it. Then, free the original
> > buffer using freedtoa().
> 
> Basically this is ok. But the question is this.  Isn't it possible
> to redefine the allocator in gdtoa so that it uses a Balloced buffer
> right away?  Forinstance, by using overloading macros?  That would
> allow to get away without having to copy stuff...

Thanks for the advice. I tried that. Please check v2 patch.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>