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Re: realloc documentation

From: Bruno Haible
Subject: Re: realloc documentation
Date: Tue, 21 Apr 2009 12:37:25 +0200
User-agent: KMail/1.9.9

Pádraig Brady wrote:
> ... then we need to use realloc like this I think:
>   errno=0
>   np = realloc (p, n);
>   if (np==NULL && errno==ENOMEM) {
>     free (p);
>     error ();
>   }
> I.E. xrealloc etc. should be changed to check ENOMEM as above?

This way of checking realloc's return value is a correct one. But the one
we have in lib/xmalloc.c currently is correct as well. The difference
between the two is when p == NULL && n == 0 on glibc systems. In this case,
  - your proposed code realizes that glibc was out of memory and fails,
  - the current code returns NULL, like it would do on AIX and OSF/1 systems.
Since xrealloc does not guarantee that xrealloc(NULL,0) != NULL, failing in
this situation on glibc is unnecessary.


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