Guardian Native C Library Calls Reference Manual (G06.28+, H06.05+)

dlopen(3) Guardian Native C Library Calls Reference Manual

Symbol controls within the loadﬁles affect a call to dlopen(); that is, the library designated by

object_pathname and each library it requires can be localized, globalized, or semi-globalized

itself, and its symbols are resolved accordingly.

dlopen() does not load licensed libraries.

Controlling the Loader Search Path

Users can specify the search path used to ﬁnd libraries without fully qualiﬁed ﬁle names. The

search path can be speciﬁed through path lists, either at link time or at run time. The path list (a

colon-separated sequence of path list elements) supplied at link and load time also applies to any

dlopen() invocations when that process is running. Each path list element is an OSS directory

pathname (for OSS processes) or a Guardian subvolume name (for Guardian processes).

The search path for the libraries that rld and dlopen( ) use is not used to search for public

libraries. Instead, the operating system makes public libraries available to rld and dlopen( ).

When building a loadﬁle, users can specify a run-time path list at link time using the ld or eld

command. This information is stored in the .dynamic section of the object ﬁle as the values for

rpath and rpath_ﬁrst for use by rld and dlopen( ) at load time.

If rpath is absent or null, the default run-time path list is:

1. Public libraries

2. Program location

3. Default locations:

On OSS: /lib:/usr/lib:/usr/local/lib:/G/SYSTEM/ZDLL

On Guardian: $SYSTEM.ZDLL

The linker (ld or eld) can place path lists in the loadﬁle, using the following options:

-rld_l path_list[:path_list]...

This option speciﬁes one or more path lists for the run-time loader to look for

libraries

-rld_first_l path_list[:path_list]...

This option is like -rld_l except that it speciﬁes places to look before looking in

the public libraries. The resulting path list is placed as a separate rpath_ﬁrst

item in the .dynamic section of the loadﬁle.

The loader uses these path lists in the target environment. Invalid path list elements or path list

elements for locations without libraries are ignored, so the list can contain a mix of Guardian

subvolume names and OSS directory names.

At link time, the ld or eld command option -limit_runtime_paths can be speciﬁed to limit the

loader’s path list at run time. When this option is speciﬁed, the items marked with an asterisk (*)

in the search lists described in this reference page are omitted from the search.

When the ld or eld loadﬁle options are used, the run-time search path list becomes:

1. Locations speciﬁed by -rld_ﬁrst_l at link time (the value of rpath_ﬁrst)

2. Public libraries

3. Program location *

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