HP-UX Reference (11i v2 03/08) - 3 Library Functions N-Z (vol 7)

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shl_load(3X) shl_load(3X)

shl_gethandle()

DIAGNOSTICS

If a library cannot be loaded,

shl_load() returns NULL and sets

errno to indicate the error. This

includes trying to

shl_load() a library containing thread local storage. All other functions return −1

on error and set

errno.

shl_findsym()

cannot ﬁnd the indicated symbol, errno is set to zero. On PA32 compatibility

mode only, if

shl_findsym()

ﬁnds the indicated symbol but cannot resolve all the symbols it depends

on,

errno is set to ENOSYM.

ERRORS

Possible values for

errno include:

[ENOEXEC] The speciﬁed ﬁle is not a shared library, or a format error was detected.

[ENOSYM] Some symbol required by the shared library could not be found.

[EINVAL] The speciﬁed handle or index is not valid or an attempt was made to load a library

at an invalid address.

[ENOMEM] There is insufﬁcient room in the address space to load the library.

[ENOENT] The speciﬁed library does not exist.

[EACCES] Read or execute permission is denied for the speciﬁed library.

WARNINGS

shl_unload() detaches the library from the process and frees the memory allocated for it, but does not

break existing symbolic linkages into the library. In this respect, an unloaded shared library is much like

a block of memory deallocated via free() (see malloc (3C)).

Some implementations may not, by default, export all symbols deﬁned by a program (instead exporting

only those symbols that are imported by a shared library seen at link time). Therefore the

-E option to

ld(1) should be used when using these routines if the loaded libraries are to refer to program symbols.

All symbol information returned by

shl_getsymbols()

, including the name ﬁeld, become invalid once

the associated library is unloaded by

shl_unload(). This is also true if a library is unloaded by a call

to dlclose().

Use caution when building shared libraries with external library dependencies. Any library that contains

Thread Local Storage (TLS) and uses static TLS model should not be used as a dependency. See "Thread

Local Storage" in dld.so(5) for more information. If a dependent library contains TLS, was built with

static TLS model and it is not loaded during program startup (that is, not linked against the executable),

the dynamic loader fails to perform the operation. You can use

+tls=dynamic compiler option to re-

compile the library to avoid errors.

When a routine or ﬂag is used which may not be supported in the future, the dynamic loader can display

a warning message. See the WARNINGS section in dld.sl(5) for further details.

Future HP-UX environments may not support these routines and ﬂags or may only support a subset of

them. Instead, they will use the SVR4 dynamic loading API. Users are encouraged to migrate to the

dl* family of dynamic linking routines. See the dlclose(3C), dlerror(3C), dlget(3C), dlgetname(3C),

dlmodinfo(3C), dlopen(3C), and dlsym(3C) man pages for more information.

AUTHOR

shl_load(3X) and related functions were developed by HP.