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Re: Size zero allocations

X-seq: zsh-workers 13584
From: Dan Nelson <dnelson@xxxxxxxxxxxx>
To: Bart Schaefer <schaefer@xxxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: Size zero allocations
Date: Tue, 6 Mar 2001 11:27:16 -0600
Cc: zsh-workers@xxxxxxxxxx
In-reply-to: <1010306171335.ZM10796@xxxxxxxxxxxxxxxxxxxxxxx>; from "Bart Schaefer" on Tue Mar 6 17:13:34 GMT 2001
Mailing-list: contact zsh-workers-help@xxxxxxxxxx; run by ezmlm
References: <1010306171335.ZM10796@xxxxxxxxxxxxxxxxxxxxxxx>

In the last episode (Mar 06), Bart Schaefer said:
> Press kill-whole-line at an empty prompt, and ElectricFence reports:
> 
> zagzig% ^U
> ElectricFence Aborting: Allocating 0 bytes, probably a bug.
> 
> Is this, in fact, a bug?

Probably.  The Single Unix specs read:

    If the size of the space requested is 0, the behaviour is
    implementation-dependent; the value returned will be either a null
    pointer or a unique pointer.

FreeBSD's malloc can be configured to return either (it defaults to
returning a pointer to a 0-byte malloc structure), and comments:

    It can be argued that returning a null pointer when asked to
    allocate zero bytes is a silly response to a silly question.

Tru64 returns NULL, and Solaris 8's manpage seems to imply that it
returns a pointer.

-- 
	Dan Nelson
	dnelson@xxxxxxxxxxxx

References:
- Size zero allocations
  - From: Bart Schaefer

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