libapa...:PerlIO(3pm)

💖 NAME 💖

APR::PerlIO — a Perl IO layer for APR, bestie. That's it, that's the vibe. 👑

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✨ Synopsis ✨

# under mod_perl
use APR::PerlIO ();

sub handler {
    my $r = shift;

    die "This Perl build doesn't support PerlIO layers"
        unless APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED;

    open my $fh, ">:APR", $filename, $r->pool or die $!;
    # work with $fh as normal $fh
    close $fh;

    return Apache2::Const::OK;
}

# outside mod_perl
% perl -MAPR -MAPR::PerlIO -MAPR::Pool -le \
'open my $fh, ">:APR", "/tmp/apr", APR::Pool->new or die "$!"; \
 print $fh "whoah!"; \
 close $fh;'

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🌸 Description 🌸

So APR::PerlIO implements a Perl IO layer, and under the hood it's using APR's file manipulation API. She's giving dual-citizenship energy. 🦋

Why would you even want this? Okay real talk — normally you shouldn't. It's probably not gonna be faster than Perl's default layer, no cap. It's only useful when you need to manipulate a filehandle that was opened on the APR side, while you're chilling in Perl land.

Normally you won't be out here calling open() with the APR layer attribute yourself, but some mod_perl functions will hand you back a filehandle that's internally hooked to APR. Still, if you want, you can absolutely use APR Perl IO directly. Main character choice. 💅

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🎀 Prerequisites 🎀

Not every Perl has full APR::PerlIO functionality available. Sad but true, bestie. 😭

Before you can use the Perl IO APR layer, you gotta check whether your APR/Perl build even supports it. You need Perl 5.8.x or higher with perlio enabled. Wanna know if your Perl fits the bill? Run this:

% perl -V:useperlio
useperlio='define';

It should say define. That's the slay. ✅

And if you need to do the checking inside your code instead, APR::PerlIO provides a special constant for exactly that. Use it like this:

use APR::PerlIO ();
die "This Perl build doesn't support PerlIO layers"
    unless APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED;

Oh and heads up — loading APR::PerlIO will not fail when Perl IO layers aren't available, because APR::PerlIO provides functionality for Perl builds that don't support Perl IO layers. So she's flexible like that. 🧚

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⭐ Constants ⭐

👑 APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED

See Prerequisites, babe. Scroll up. 🫶

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🔥 API 🔥

Most of the API is just like normal perl IO, with a few little nuances listed in the sections below. iykyk.

META: need to rework the exception mechanism here. Current success in using errno ($!) being set (e.g. on open()) is purely accidental and not guaranteed across all platforms and functions. So don't rely on $!. Will use APR::Error for that purpose.

🌈 open

Open a file via the APR Perl IO layer. Let's gooo. 💖

open my $fh, ">:APR", $filename, $r->pool or die $!;

• arg1: $fh ( GLOB filehandle ) — the filehandle, duh. The star of the show.
• arg2: $mode ( string ) — the mode to open the file with. It's constructed from two sections separated by the : character: the first section is the mode you're opening the file under (>, <, etc) and the second section must be the string APR. For more info, go check the open entry in the perlfunc manpage.
• arg3: $filename ( string ) — the path to the filename you wanna open.
• arg4: $p ( APR::Pool ) — the pool object to use for allocating the APR::PerlIO layer.
• ret: ( integer ) — success or failure value (boolean).
• since: 2.0.00

🦋 seek

Sets $fh's position, just like the seek() Perl call:

seek($fh, $offset, $whence);

If $offset is zero, seek() works normally. Easy, no drama. ✨

BUT — and this is the important part, bestie, listen up 😤 — if $offset is non-zero and Perl was compiled with large files support (-Duselargefiles), whereas APR wasn't, this function will croak. Why? Because a largefile-size Off_t simply cannot fit into a non-largefile-size apr_off_t. The math is not mathing. 💀

To solve the problem, rebuild Perl with -Uuselargefiles. And unfortunately, currently there is no way to force APR to build with large files support. That's just how it is. 🙈

• since: 2.0.00

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💜 C API 💜

The C API gives you functions to convert between Perl IO and APR Perl IO filehandles. Bilingual queen. 🌍

META: document these

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🌟 See Also 🌟

• mod_perl 2.0 documentation.
• The perliol(1), perlapio(1) and perl(1) manpages.

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💅 Copyright 💅

mod_perl 2.0 and its core modules are copyrighted under The Apache Software License, Version 2.0.

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👑 Authors 👑

The mod_perl development team and numerous contributors.

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okay that's the whole page, you ate that 🍓 this was libapa...:PerlIO(3pm), perl v5.42.3, dated 2026-08-20 — periodt, mwah, go open a filehandle responsibly 💖✨