# ACE_DLL_Handle Class Reference

Provides an abstract interface for handling various DLL operations. More...

`#include <DLL_Manager.h>`

List of all members.

## Public Member Functions

| ACE_DLL_Handle (void)
| Default construtor.
| ~ACE_DLL_Handle (void)
| Destructor.
const ACE_TCHAR * | dll_name () const
| Returns the name of the shared library (without prefixes or suffixes).
int | open (const ACE_TCHAR *dll_name, int open_mode, ACE_SHLIB_HANDLE handle)
int | close (int unload=0)
sig_atomic_t | refcount (void) const
| Return the current refcount.
void * | symbol (const ACE_TCHAR *symbol_name, int ignore_errors=0)
ACE_SHLIB_HANDLE | get_handle (int become_owner=0)

## Private Member Functions

auto_ptr< ACE_TString > | error (void)
void | get_dll_names (const ACE_TCHAR *dll_name, ACE_Array< ACE_TString > &try_names)
| ACE_DLL_Handle (const ACE_DLL_Handle &)
void | operator= (const ACE_DLL_Handle &)

## Private Attributes

sig_atomic_t | refcount_
ACE_TCHAR * | dll_name_
| Name of the shared library.
ACE_SHLIB_HANDLE | handle_
| Handle to the actual library loaded by the OS.

## Static Private Attributes

sig_atomic_t | open_called_ = 0

## Detailed Description

Provides an abstract interface for handling various DLL operations.

This class is an wrapper over the various methods for utilizing a dynamically linked library (DLL), which is called a shared library on some platforms. It is refcounted and managed by ACE_DLL_Manager, so there will only be a single instance of this class for each dll loaded, no matter how many instances of ACE_DLL an application has open. Operations <open>, <close>, and <symbol> have been implemented to help opening/closing and extracting symbol information from a DLL, respectively.

Most of this class came from the original ACE_DLL class. ACE_DLL is now just an interface that passed all it's calls either directly or via ACE_DLL_Manager to this class for execution.

## Constructor & Destructor Documentation

ACE_DLL_Handle::ACE_DLL_Handle | ( | void |  | ) |

| Default construtor.

ACE_DLL_Handle::~ACE_DLL_Handle | ( | void |  | ) |

| Destructor.

ACE_DLL_Handle::ACE_DLL_Handle | ( | const ACE_DLL_Handle & |  | ) | `[private]`

## Member Function Documentation

int ACE_DLL_Handle::close | ( | int | unload = `0` | ) |

| Call to close the DLL object. If unload = 0, it only decrements the refcount, but if unload = 1, then it will actually unload the library when the refcount == 0;

const ACE_TCHAR * ACE_DLL_Handle::dll_name | ( |  | ) | const

| Returns the name of the shared library (without prefixes or suffixes).

auto_ptr< ACE_TString > ACE_DLL_Handle::error | ( | void |  | ) | `[private]`

| Returns a pointer to a string explaining why <symbol> or <open> failed. This is used internal to print out the error to the log, but since this object is shared, we can't store or return the error to the caller.

void ACE_DLL_Handle::get_dll_names | ( | const ACE_TCHAR * | dll_name,
|  | ACE_Array< ACE_TString > & | try_names
| ) | `[private]`

ACE_SHLIB_HANDLE ACE_DLL_Handle::get_handle | ( | int | become_owner = `0` | ) |

| Return the handle to the caller. If become_owner is non-0 then caller assumes ownership of the handle so we decrement the retcount.

int ACE_DLL_Handle::open | ( | const ACE_TCHAR * | dll_name,
|  | int | open_mode,
|  | ACE_SHLIB_HANDLE | handle
| ) |

This method opens and dynamically links dll_name. The default mode is <rtld_lazy>, which loads identifier symbols but not the symbols for functions, which are loaded dynamically on-demand. Other supported modes include: <rtld_now>, which performs all necessary relocations when dll_name is first loaded and <rtld_global>, which makes symbols available for relocation processing of any other DLLs. Returns -1 on failure and 0 on success.

void ACE_DLL_Handle::operator= | ( | const ACE_DLL_Handle & |  | ) | `[private]`

sig_atomic_t ACE_DLL_Handle::refcount | ( | void |  | ) | const

| Return the current refcount.

void * ACE_DLL_Handle::symbol | ( | const ACE_TCHAR * | symbol_name,
|  | int | ignore_errors = `0`
| ) |

| If symbol_name is in the symbol table of the DLL a pointer to the symbol_name is returned. Otherwise, returns 0. Set the ignore_errors flag to supress logging errors if symbol_name isn't found. This is nice if you just want to probe a dll to see what's available, since missing functions in that case aren't really errors.

## Member Data Documentation

ACE_TCHAR* ACE_DLL_Handle::dll_name_`[private]`

| Name of the shared library.

ACE_SHLIB_HANDLE ACE_DLL_Handle::handle_`[private]`

| Handle to the actual library loaded by the OS.

ACE_BEGIN_VERSIONED_NAMESPACE_DECL sig_atomic_t ACE_DLL_Handle::open_called_ = 0`[static, private]`

| Keeps track of whether or not open() has ever been called. This helps get around problem on Linux, and perhaps other OS's, that seg-fault if dlerror() is called before the ld library has been initialized by a call to dlopen().

sig_atomic_t ACE_DLL_Handle::refcount_`[private]`

The documentation for this class was generated from the following files:

- DLL_Manager.h
- DLL_Manager.cpp