apr::perlio.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

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.\" ========================================================================
.\"
.IX Title "mod_perl-2.0.2::docs::api::APR::PerlIO 3"
.TH mod_perl-2.0.2::docs::api::APR::PerlIO 3 "2005-10-21" "perl v5.10.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.if n .ad l
.nh
.SH "NAME"
APR::PerlIO \-\- Perl IO layer for APR
.SH "Synopsis"
.IX Header "Synopsis"
.Vb 2
\&  # under mod_perl
\&  use APR::PerlIO ();
\&  
\&  sub handler {
\&      my $r = shift;
\&  
\&      die "This Perl build doesn\*(Aqt 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 \e
\&  \*(Aqopen my $fh, ">:APR", "/tmp/apr", APR::Pool\->new or die "$!"; \e
\&   print $fh "whoah!"; \e
\&   close $fh;\*(Aq
.Ve
.SH "Description"
.IX Header "Description"
\&\f(CW\*(C`APR::PerlIO\*(C'\fR implements a Perl \s-1IO\s0 layer using \s-1APR\s0's file
manipulation \s-1API\s0 internally.
.PP
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 \s-1APR\s0 side, while using Perl.
.PP
Normally you won't call \fIopen()\fR with \s-1APR\s0 layer attribute, but some
mod_perl functions will return a filehandle which is internally hooked
to \s-1APR\s0. But you can use \s-1APR\s0 Perl \s-1IO\s0 directly if you want.
.SH "Prerequisites"
.IX Header "Prerequisites"
Not every Perl will have full \f(CW\*(C`APR::PerlIO\*(C'\fR functionality available.
.PP
Before using the Perl \s-1IO\s0 \s-1APR\s0 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:
.PP
.Vb 2
\&  % perl \-V:useperlio
\&  useperlio=\*(Aqdefine\*(Aq;
.Ve
.PP
It should say \fIdefine\fR.
.PP
If you need to do the checking in the code, there is a special
constant provided by \f(CW\*(C`APR::PerlIO\*(C'\fR, which can be used as follows:
.PP
.Vb 3
\&  use APR::PerlIO ();
\&  die "This Perl build doesn\*(Aqt support PerlIO layers"
\&      unless APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED;
.Ve
.PP
Notice that loading \f(CW\*(C`APR::PerlIO\*(C'\fR won't fail when Perl \s-1IO\s0 layers
aren't available since \f(CW\*(C`APR::PerlIO\*(C'\fR provides functionality for Perl
builds not supporting Perl \s-1IO\s0 layers.
.SH "Constants"
.IX Header "Constants"
.ie n .Sh """APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED"""
.el .Sh "\f(CWAPR::PerlIO::PERLIO_LAYERS_ARE_ENABLED\fP"
.IX Subsection "APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED"
See Prerequisites.
.SH "API"
.IX Header "API"
Most of the \s-1API\s0 is as in normal perl \s-1IO\s0 with a few nuances listed in
the following sections.
.PP
\&\s-1META:\s0 need to rework the exception mechanism here. Current success in
using errno ($!) being set (e.g. on \fIopen()\fR) is purely accidental and
not guaranteed across all platforms and functions. So don't rely on
$!. Will use \f(CW\*(C`APR::Error\*(C'\fR for that
purpose.
.ie n .Sh """open"""
.el .Sh "\f(CWopen\fP"
.IX Subsection "open"
Open a file via \s-1APR\s0 Perl \s-1IO\s0 layer.
.PP
.Vb 1
\&  open my $fh, ">:APR", $filename, $r\->pool or die $!;
.Ve
.ie n .IP "arg1: $fh ( \s-1GLOB\s0 filehandle )" 4
.el .IP "arg1: \f(CW$fh\fR ( \s-1GLOB\s0 filehandle )" 4
.IX Item "arg1: $fh ( GLOB filehandle )"
The filehandle.
.ie n .IP "arg2: $mode ( string )" 4
.el .IP "arg2: \f(CW$mode\fR ( string )" 4
.IX Item "arg2: $mode ( string )"
The mode to open the file, constructed from two sections separated by
the \f(CW\*(C`:\*(C'\fR character: the first section is the mode to open the file
under (>, <, etc) and the second section must be a string
\&\fI\s-1APR\s0\fR. For more information refer to the \fIopen\fR entry in the
\&\fIperlfunc\fR manpage.
.ie n .IP "arg3: $filename ( string )" 4
.el .IP "arg3: \f(CW$filename\fR ( string )" 4
.IX Item "arg3: $filename ( string )"
The path to the filename to open
.ie n .IP "arg4: $p\fR ( \f(CW""APR::Pool"" )" 4
.el .IP "arg4: \f(CW$p\fR ( \f(CWAPR::Pool\fR )" 4
.IX Item "arg4: $p ( APR::Pool )"
The pool object to use to allocate APR::PerlIO layer.
.IP "ret: ( integer )" 4
.IX Item "ret: ( integer )"
success or failure value (boolean).
.IP "since: 2.0.00" 4
.IX Item "since: 2.0.00"
.ie n .Sh """seek"""
.el .Sh "\f(CWseek\fP"
.IX Subsection "seek"
Sets \f(CW$fh\fR's position, just like the \f(CW\*(C`seek()\*(C'\fR Perl call:
.PP
.Vb 1
\&  seek($fh, $offset, $whence);
.Ve
.PP
If \f(CW$offset\fR is zero, \f(CW\*(C`seek()\*(C'\fR works normally.
.PP
However if \f(CW$offset\fR is non-zero and Perl has been compiled with with
large files support (\f(CW\*(C`\-Duselargefiles\*(C'\fR), whereas \s-1APR\s0 wasn't, this
function will croak. This is because largefile size \f(CW\*(C`Off_t\*(C'\fR simply
cannot fit into a non-largefile size \f(CW\*(C`apr_off_t\*(C'\fR.
.PP
To solve the problem, rebuild Perl with \f(CW\*(C`\-Uuselargefiles\*(C'\fR. Currently
there is no way to force \s-1APR\s0 to build with large files support.
.IP "since: 2.0.00" 4
.IX Item "since: 2.0.00"
.SH "C API"
.IX Header "C API"
The C \s-1API\s0 provides functions to convert between Perl \s-1IO\s0 and \s-1APR\s0 Perl
\&\s-1IO\s0 filehandles.
.PP
\&\s-1META:\s0 document these
.SH "See Also"
.IX Header "See Also"
mod_perl 2.0 documentation. The \fI\fIperliol\fI\|(1)\fR,
\&\fI\fIperlapio\fI\|(1)\fR and \fI\fIperl\fI\|(1)\fR manpages.
.SH "Copyright"
.IX Header "Copyright"
mod_perl 2.0 and its core modules are copyrighted under
The Apache Software License, Version 2.0.
.SH "Authors"
.IX Header "Authors"
The mod_perl development team and numerous
contributors.