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Class: Fiddle::Handle

Relationships & Source Files
Inherits: Object
Defined in: ext/fiddle/handle.c

Overview

The Handle is the manner to access the dynamic library

Example

Setup

libc_so = "/lib64/libc.so.6"
#=> "/lib64/libc.so.6"
@handle = Fiddle::Handle.new(libc_so)
#=> #<Fiddle::Handle:0x00000000d69ef8>

Setup, with flags

libc_so = "/lib64/libc.so.6"
#=> "/lib64/libc.so.6"
@handle = Fiddle::Handle.new(libc_so, Fiddle::RTLD_LAZY | Fiddle::RTLD_GLOBAL)
#=> #<Fiddle::Handle:0x00000000d69ef8>

See RTLD_LAZY and RTLD_GLOBAL

Addresses to symbols

strcpy_addr = @handle['strcpy']
#=> 140062278451968

or

strcpy_addr = @handle.sym('strcpy')
#=> 140062278451968

Constant Summary

  • DEFAULT =

    A predefined pseudo-handle of RTLD_DEFAULT

    Which will find the first occurrence of the desired symbol using the default library search order

    # File 'ext/fiddle/handle.c', line 438 
    predefined_fiddle_handle(RTLD_DEFAULT)
  • NEXT =

    A predefined pseudo-handle of RTLD_NEXT

    Which will find the next occurrence of a function in the search order after the current library.

    # File 'ext/fiddle/handle.c', line 429 
    predefined_fiddle_handle(RTLD_NEXT)
  • RTLD_GLOBAL =

    :Handle flag.

    The symbols defined by this library will be made available for symbol resolution of subsequently loaded libraries.

    # File 'ext/fiddle/handle.c', line 447 
    rtld Fiddle
  • RTLD_LAZY =

    :Handle flag.

    Perform lazy binding. Only resolve symbols as the code that references them is executed. If the symbol is never referenced, then it is never resolved. (Lazy binding is only performed for function references; references to variables are always immediately bound when the library is loaded.)

    # File 'ext/fiddle/handle.c', line 459 
    rtld Fiddle
  • RTLD_NOW =

    :Handle flag.

    If this value is specified or the environment variable LD_BIND_NOW is set to a nonempty string, all undefined symbols in the library are resolved before Fiddle.dlopen returns. If this cannot be done an error is returned.

    # File 'ext/fiddle/handle.c', line 470 
    rtld Fiddle

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(library = nil, flags = Fiddle::RTLD_LAZY | Fiddle::RTLD_GLOBAL)

Create a new handler that opens library with flags.

If no library is specified or nil is given, DEFAULT is used, which is the equivalent to RTLD_DEFAULT. See man 3 dlopen for more.

lib = Fiddle::Handle.new

The default is dependent on OS, and provide a handle for all libraries already loaded. For example, in most cases you can use this to access libc functions, or ruby functions like rb_str_new.

Class Method Details

.[](name) Also known as: .sym

Get the address as an Integer for the function named name.

.[](name) .sym(name)

Alias for .[].

Instance Attribute Details

#close_enabled? ⇒ Boolean (readonly)

Returns true if dlclose() will be called when this handle is garbage collected.

See man(3) dlclose() for more info.

Instance Method Details

#[](name) Also known as: #sym

Get the address as an Integer for the function named name. The function is searched via dlsym on RTLD_NEXT.

See man(3) dlsym() for more info.

#close

#disable_close

Disable a call to dlclose() when this handle is garbage collected.

#enable_close

Enable a call to dlclose() when this handle is garbage collected.

#[](name) #sym(name)

Alias for #[].

#to_i ⇒ Integer

Returns the memory address for this handle.