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Sys-GNU-ldconfig-0.03
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/ Sys::GNU::ldconfig

NAME

Sys::GNU::ldconfig - Search for shared libraries

SYNOPSIS

    use Sys::GNU::ldconfig;

    my $libso = ld_lookup( 'k5crypto' );    # /usr/lib64/libk5crypto.so on CentOS 5.8
    $libso = ld_lookup( 'libk5crypto' );    # same thing
    
    my $ld = Sys::GNU::ldconfig->new;
    $libso = $ld->lookup( 'k5crypto' );     # same again
    $libso = $ld->lookup( 'libk5crypto' );  # still the same

DESCRIPTION

Sys::GNU::ldconfig reproduces the logic used by ldconfig and ld.so to find a shared library (.so or .dll). It is intended for modules like PAR::Packer, that repackage code.

Sys::GNU::ldconfig will search the following places in order for a shared library:

LD_LIBRARY_PATH

This is a colon : seperated list of directories. Because it is named differently on some systems, ld_lookup uses $Config::Config{ldlibpthname}.

/etc/ld.so.conf

This file contains a list of directories to search. Directories are seperated by comma (,), space ( ), colon (:) or newline (\n). May also contain an "include" directive, which is a file glob of other config files to include.

Trusted directories
    /lib64
    /lib
    /usr/lib64
    /lib

These directories are hardcoded into ldconfig.

FUNCTIONS

ld_lookup

    $so = ld_lookup( 'k5cyrpto' );
    $so = ld_lookup( 'libk5cyrpto' );
    $so = ld_lookup( 'libk5cyrpto.so.13' );

Find a shared library. Works with the library name (k5crypto), filename (libk5crypto.so) or versioned filename (libk5cyrpto.so.13).

Returns the full path to the major version of the library, for example /usr/lib64/libcurl.so.4 and not the full versioned (/usr/lib64/libcurl.so.4.2.0 or unversioned (/usr/lib64/libcurl.so).

When first called, ld_lookup creates a list of directories to search. Subsequent calls will reuse this list. The list is cleared by calling "ld_root".

ld_root

    ld_root( '/mnt' );

Sets the root directory. Defaults to /. This is roughly equivalent to doing chroot(2) before calling "ld_lookup". Note that ld_lookup will return a file path with the root stripped out.

Setting the root directory will clear the list of directories to search.

METHODS

Sys::GNU::ldconfig also provides an object-oriented interface.

new

    $ld = Sys::GNU::Lookup->new;

Create an object.

lookup

    my $so = $ld->lookup( 'k5cyrpto' );

Find a shared library.

dirs

    my @dirs = $ld->dirs;

Returns a list of directories that will be searched for shared libraries.

root

    $ld->root( '/mnt' );

Set the root directory to search in.

SEE ALSO

ld.so(8), ldconfig.

AUTHOR

Philip Gwyn, <gwyn -AT- cpan.org>

COPYRIGHT AND LICENSE

Copyright (C) 2013-2023 by Philip Gwyn

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available.