Re: Question about PERL_NO_DEV_RANDOM

Dang... thanks for sanity checking me.

It would have been a nice clean-up.

-- Scott

On 1/22/2026 8:02 PM, Tony Cook wrote:
> On Thu, Jan 22, 2026 at 06:47:24PM -0800, Scott Baker wrote:
>> As part of my clean up for Perl_seed() I see we have this weird define
>> PERL_NO_DEV_RANDOM. Grepping the source code the ONLY place I see that
>> defined is in *dosish.h* which appears to be a config file for building Perl
>> for old DOS systems. Do we use *dosish.h *for any modern supported systems?
>>
>> The only thing this define does is tell Perl_seed() skip trying to read from
>> */dev/urandom*. Since this is for older DOS systems which I don't think we
>> support (?) can this check be removed? Without that define in place, even on
>> DOS systems, the code will fail to read from */dev/urandom* (because it
>> doesn't exist) and fail back to hashing state variables instead.
> Win32 is considered DOSISH and dosish.h is included on Win32, from
> perl.h:
>
> /* define this once if either system, instead of cluttering up the src */
> #if defined(WIN32)
> #define DOSISH 1
> #endif
> ...
> #ifdef DOSISH
> #   if defined(OS2)
> #       include "os2ish.h"
> #   else
> #       include "dosish.h"
> #   endif
> #elif defined(VMS)
> ...
>
> Someone building perl on Configure based systems can add
> -Accflags=-DPERL_NO_DEV_RANDOM to skip trying /dev/urandom.
>
>> Nothing would change in the codepath, it would just make the code cleaner
>> and more readable by having one less obscure define.
> It's still in use, so it should stay.
>
> Tony
>