Package org.lwjgl.system.macosx

Class DynamicLinkLoader

java.lang.Object

org.lwjgl.system.macosx.DynamicLinkLoader

public class DynamicLinkLoader
extends java.lang.Object

Native bindings to .

Field Summary

Fields

Modifier and Type	Field and Description
static long	RTLD_DEFAULT Special-handle values for DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer).
static int	RTLD_GLOBAL RTLD_LAZY RTLD_LOCAL The mode argument to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int) contains one of the following.
static long	RTLD_MAIN_ONLY RTLD_NEXT Special-handle values for DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer).
static int	RTLD_NOW The mode argument to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int) contains one of the following.
static long	RTLD_SELF Special-handle values for DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer).

Method Summary

Modifier and Type	Method and Description
static int	dlclose(long handle) Closes a dynamic library or bundle.
static java.lang.String	dlerror() Provides diagnostic information corresponding to problems with calls to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int), DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer), and DynamicLinkLoader.dlclose(long) in the same thread.
static long	dlopen(java.nio.ByteBuffer path, int mode) Loads and links a dynamic library or bundle.
static long	dlopen(java.lang.CharSequence path, int mode) Loads and links a dynamic library or bundle.
static long	dlsym(long handle, java.nio.ByteBuffer name) Returns the address of a symbol.
static long	dlsym(long handle, java.lang.CharSequence name) Returns the address of a symbol.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

RTLD_LAZY, RTLD_NOW, RTLD_LOCAL, RTLD_GLOBAL

The mode argument to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int) contains one of the following.

RTLD_NEXT, RTLD_DEFAULT, RTLD_SELF, RTLD_MAIN_ONLY

Special-handle values for DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer).

Method Detail

dlopen

public static long dlopen(java.nio.ByteBuffer path,
                          int mode)

public static long dlopen(java.lang.CharSequence path,
                          int mode)

Loads and links a dynamic library or bundle.

This function examines the Mach-O file specified by path. If the image is compatible with the current process and has not already been loaded into the process, the image is loaded and linked. If the image contains initializer functions, they are executed before this function returns.

Subsequent calls to dlopen to load the same image return the same handle, but the internal reference count for the handle is incremented. Therefore, all dlopen calls must be balanced with DynamicLinkLoader.dlclose(long) calls.

For efficiency, the DynamicLinkLoader.RTLD_LAZY binding mode is preferred over DynamicLinkLoader.RTLD_NOW. However, using DynamicLinkLoader.RTLD_NOW ensures that any undefined symbols are discovered during the call to dlopen.

The dynamic loader looks in the paths specified by a set of environment variables, and in the process's current directory, when it searches for a library. These paths are called dynamic loader search paths. The environment variables are LD_LIBRARY_PATH, DYLD_LIBRARY_PATH, and DYLD_FALLBACK_LIBRARY_PATH. The default value of DYLD_FALLBACK_LIBRARY_PATH (used when this variable is not set), is $HOME/lib;/usr/local/lib;/usr/lib.

The order in which the search paths are searched depends on whether path is a filename (it does not contain a slash) or a pathname (it contains at least one slash).

When path is a filename, the dynamic loader searches for the library in the search paths in the following order:

• $LD_LIBRARY_PATH
• $DYLD_LIBRARY_PATH
• The process's working directory
• $DYLD_FALLBACK_LIBRARY_PATH

When path is a pathname, the dynamic loader searches for the library in the search paths in the following order:

• $DYLD_LIBRARY_PATH
• The given pathname
• $DYLD_FALLBACK_LIBRARY_PATH using the filename

Parameters:

path - path to the image to open

mode - specifies when the loaded image's external symbols are bound to their definitions in dependent libraries (lazy or at load time) and the visibility of the image's exported symbols (global or local). The value of this parameter is made up by ORing one binding behavior value with one visibility specification value.

The following values specify the binding behavior:

• DynamicLinkLoader.RTLD_LAZY (default): Each external symbol reference is bound the first time it's used.
• DynamicLinkLoader.RTLD_NOW: All external symbol references are bound immediately.

The following values specify external symbol visibility:

• DynamicLinkLoader.RTLD_GLOBAL (default): The loaded image's exported symbols are available to any images that use a flat namespace or to calls to dlsym when using a special handle (see DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer) for details).
• DynamicLinkLoader.RTLD_LOCAL: The loaded image's exported symbols are generally hidden. They are available only to DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer) invocations that use the handle returned by this function.

dlerror

public static java.lang.String dlerror()

Provides diagnostic information corresponding to problems with calls to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int), DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer), and DynamicLinkLoader.dlclose(long) in the same thread.

When there's a problem to report, this function returns a pointer to a null-terminated string describing the problem. Otherwise, this function returns NULL.

Each call to dlerror resets its diagnostic buffer. If a program needs to keep a record of past error messages, it must store them itself. Subsequent calls to dlerror in the same thread with no calls to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int), DynamicLinkLoader.dlsym(long, java.nio.ByteBuffer), or DynamicLinkLoader.dlclose(long), return NULL.

dlsym

public static long dlsym(long handle,
                         java.nio.ByteBuffer name)

public static long dlsym(long handle,
                         java.lang.CharSequence name)

Returns the address of a symbol.

The value of handle specifies what images this function searches for to locate the symbol specified by the symbol parameter. The following table describes the possible values for the handle parameter:

Handle value	Search scope
dlopen handle	Image associated with the DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int) handle.
DynamicLinkLoader.RTLD_DEFAULT	Every dependent library or DynamicLinkLoader.RTLD_GLOBAL–opened library in the current process, in the order they were loaded.
DynamicLinkLoader.RTLD_NEXT	Dependent libraries that were loaded after the one calling this function. Libraries opened with DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int) are not searched.

Unlike in the NS... functions, the symbol parameter doesn't require a leading underscore to be part of the symbol name.

Parameters:

handle - a handle obtained by a call to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int), or a special handle. If the handle was obtained by a call to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int), it must not have been closed with a call to DynamicLinkLoader.dlclose(long). These are the possible special-handle values: DynamicLinkLoader.RTLD_DEFAULT, and DynamicLinkLoader.RTLD_NEXT.

name - the null-terminated character string containing the C name of the symbol being sought

dlclose

public static int dlclose(long handle)

Closes a dynamic library or bundle.

This function decreases the reference count of the image referenced by handle. When the reference count for handle becomes 0, the termination routines in the image are called, and the image is removed from the address space of the current process. After that point, handle is rendered invalid.

Parameters:

handle - a handle obtained through a call to DynamicLinkLoader.dlopen(java.nio.ByteBuffer, int).