Guardian Native C Library Calls Reference Manual (G06.28+, H06.04+)

Guardian Native C Library Calls (a - e) dlopen(3)

RTLD_VERBOSE(n)

Speciﬁes the amount and kind of debugging information to pro-

vide on the home terminal or standard error ﬁle when an error

occurs:

0 Perform the default behavior

1 Do not list warning or error messages on the

home terminal or the standard error ﬁle

2 List warning and error messages

3 List warning and error messages and ﬁles loaded

4 List warning and error messages, ﬁles loaded,

and symbol resolution

5 List warning and error messages, ﬁles loaded,

and ﬁle search details

6 List warning and error messages, ﬁles loaded,

symbol resolution, and ﬁle search details

7 List warning and error messages, ﬁles loaded,

symbol resolution, and symbol search details

8 List warning and error messages, ﬁles loaded,

symbol resolution, ﬁle search details, and sym-

bol search details

Combinations of the following are allowed:

• Only one of RTLD_LAZY, RTLD_NOW, and RTLD_NO_LOAD

• Only one of RTLD_GLOBAL and RTLD_LOCAL

• RTLD_VERBOSE(n)

dlopen() treats the mode parameter as the sum of the speciﬁed values and

reports an error if any other value is used. Valid values for mode cannot evaluate

to 0 (zero).

DESCRIPTION

The dlopen() function invokes the rld loader to make a loadﬁle available to a running process.

The library handle returned can be used by the dlsym( ) function to access external symbols

deﬁned in the ﬁle. A library handle created using a NULL object_pathname can be destroyed by

dlclose(), but that action has no affect on the loaded program.

A library handle is returned every time dlopen() is called successfully, even if the loadﬁle is

already loaded in the process. Loadﬁles that are already loaded in the process are not loaded

again.

Until the library handle is invalidated by a call to the dlclose() function, the library designated

by object_pathname and all the libraries that the object_pathname library requires remain

loaded. Any library handle returned by dlopen( ) counts as a usage of the target library and any

libraries it requires; until the last handle is invalidated by the dlclose() function, the library is not

unloaded.

A usage count is maintained for each library. The usage count is incremented by calls to

dlopen() and decremented by calls to dlclose(). Once the usage count indicates that a library

has become unused, it is unloaded.

527192-005 Hewlett-Packard Company 1−53