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From: Kaz Kylheku <433-929-6894@kylheku.com>
Newsgroups: comp.lang.c
Subject: Re: avoiding strdup()
Date: Mon, 11 Mar 2024 17:58:03 -0000 (UTC)
Organization: A noiseless patient Spider
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Message-ID: <20240311105508.215@kylheku.com>
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On 2024-03-11, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
> Michael S <already5chosen@yahoo.com> writes:
> [...]
>> Is there any chance at all that on typical Linux machine (i.e. the one
>> configured to overcommit virtual memory) strdup() returns NULL?
>> If it was malloc() I'd say - no chance. For strdup() I'm less sure.
>
> strdup() calls malloc(), so strdup() can return NULL if and only if
> malloc() can return NULL -- but with the additional constraint that you
> first need to have a string argument to strdup() that's long enough to
> cause a suffiently large argument to be passed to malloc().
>
> One data point: On my Ubuntu system, malloc(SIZE_MAX) returns NULL for
> very large arguments (over about 23 GiB in my quick and dirty test).

I'm guessing that might be only be because of the overcommit_ratio
value; i.e that allowing a 23 GiB increment in the allocated address
space would bring the system over the currently configured overcommit
ratio.

-- 
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