APR::PerlIO (3)

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NAME

APR::PerlIO -- Perl IO layer for APR

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;'

Description

"APR::PerlIO" implements a Perl layer using 's file manipulation internally.

Why do you want to use this? Normally you shouldn't, probably it won't be faster than Perl's default layer. It's only useful when you need to manipulate a filehandle opened at the

side, while using Perl.

Normally you won't call open() with

layer attribute, but some mod_perl functions will return a filehandle which is internally hooked to But you can use Perl directly if you want.

Prerequisites

Not every Perl will have full "APR::PerlIO" functionality available.

Before using the Perl

layer one has to check whether it's supported by the used APR/Perl build. Perl 5.8.x or higher with perlio enabled is required. You can check whether your Perl fits the bill by running:

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

It should say define.

If you need to do the checking in the code, there is a special constant provided by "APR::PerlIO", which can be used as follows:

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

Notice that loading "APR::PerlIO" won't fail when Perl

layers aren't available since "APR::PerlIO" provides functionality for Perl builds not supporting Perl layers.

Constants

APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED

See Prerequisites.

API

Most of the is as in normal perl with a few nuances listed in the following sections.

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 Perl layer.

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

arg1: $fh (

GLOB

filehandle )

The filehandle.

arg2: $mode ( string )

The mode to open the file, constructed from two sections separated by the ":" character: the first section is the mode to open the file under (>, <, etc) and the second section must be a string

APR

. For more information refer to the open entry in the perlfunc manpage.

arg3: $filename ( string )

The path to the filename to open

arg4: $p ( APR::Pool )

The pool object to use to allocate 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.

However if $offset is non-zero and Perl has been compiled with with large files support ("-Duselargefiles"), whereas

wasn't, this function will croak. This is because largefile size "Off_t" simply cannot fit into a non-largefile size "apr_off_t".

To solve the problem, rebuild Perl with "-Uuselargefiles". Currently there is no way to force

to build with large files support.

since: 2.0.00

C API

The C provides functions to convert between Perl and Perl filehandles.

document these

See Also

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

Copyright

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

Authors

The mod_perl development team and numerous contributors.