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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 435 
    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 426 
    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 444 
    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 456 
    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 467 
    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.

[ GitHub ] 

  


# File 'ext/fiddle/handle.c', line 132



static VALUE
rb_fiddle_handle_initialize(int argc, VALUE argv[], VALUE self)
{
    void *ptr;
    struct dl_handle *fiddle_handle;
    VALUE lib, flag;
    char  *clib;
    int   cflag;
    const char *err;

    switch( rb_scan_args(argc, argv, "02", &lib, &flag) ){
      case 0:
	clib = NULL;
	cflag = RTLD_LAZY | RTLD_GLOBAL;
	break;
      case 1:
	clib = NIL_P(lib) ? NULL : SafeStringValueCStr(lib);
	cflag = RTLD_LAZY | RTLD_GLOBAL;
	break;
      case 2:
	clib = NIL_P(lib) ? NULL : SafeStringValueCStr(lib);
	cflag = NUM2INT(flag);
	break;
      default:
	rb_bug("rb_fiddle_handle_new");
    }

#if defined(_WIN32)
    if( !clib ){
	HANDLE rb_libruby_handle(void);
	ptr = rb_libruby_handle();
    }
    else if( STRCASECMP(clib, "libc") == 0
# ifdef RUBY_COREDLL
	     || STRCASECMP(clib, RUBY_COREDLL) == 0
	     || STRCASECMP(clib, RUBY_COREDLL".dll") == 0
# endif
	){
# ifdef _WIN32_WCE
	ptr = dlopen("coredll.dll", cflag);
# else
	(void)cflag;
	ptr = w32_coredll();
# endif
    }
    else
#endif
	ptr = dlopen(clib, cflag);
#if defined(HAVE_DLERROR)
    if( !ptr && (err = dlerror()) ){
	rb_raise(rb_eFiddleError, "%s", err);
    }
#else
    if( !ptr ){
	err = dlerror();
	rb_raise(rb_eFiddleError, "%s", err);
    }
#endif
    TypedData_Get_Struct(self, struct dl_handle, &fiddle_handle_data_type, fiddle_handle);
    if( fiddle_handle->ptr && fiddle_handle->open && fiddle_handle->enable_close ){
	dlclose(fiddle_handle->ptr);
    }
    fiddle_handle->ptr = ptr;
    fiddle_handle->open = 1;
    fiddle_handle->enable_close = 0;

    if( rb_block_given_p() ){
	rb_ensure(rb_yield, self, rb_fiddle_handle_close, self);
    }

    return Qnil;
}


  







Class Method Details



  

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



  

    

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


  



  [ GitHub ]


  

  


# File 'ext/fiddle/handle.c', line 306



static VALUE
rb_fiddle_handle_s_sym(VALUE self, VALUE sym)
{
    return fiddle_handle_sym(RTLD_NEXT, sym);
}


  








  

    

      .[](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.


  



  [ GitHub ]


  

  


# File 'ext/fiddle/handle.c', line 242



static VALUE
rb_fiddle_handle_close_enabled_p(VALUE self)
{
    struct dl_handle *fiddle_handle;

    TypedData_Get_Struct(self, struct dl_handle, &fiddle_handle_data_type, fiddle_handle);

    if(fiddle_handle->enable_close) return Qtrue;
    return Qfalse;
}


  







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.


  



  [ GitHub ]


  

  


# File 'ext/fiddle/handle.c', line 276



static VALUE
rb_fiddle_handle_sym(VALUE self, VALUE sym)
{
    struct dl_handle *fiddle_handle;

    TypedData_Get_Struct(self, struct dl_handle, &fiddle_handle_data_type, fiddle_handle);
    if( ! fiddle_handle->open ){
	rb_raise(rb_eFiddleError, "closed handle");
    }

    return fiddle_handle_sym(fiddle_handle->ptr, sym);
}


  








  

    #close  
  

  [ GitHub ]


  

  


# File 'ext/fiddle/handle.c', line 66



static VALUE
rb_fiddle_handle_close(VALUE self)
{
    struct dl_handle *fiddle_handle;

    TypedData_Get_Struct(self, struct dl_handle, &fiddle_handle_data_type, fiddle_handle);
    if(fiddle_handle->open) {
	int ret = dlclose(fiddle_handle->ptr);
	fiddle_handle->open = 0;

	/* Check dlclose for successful return value */
	if(ret) {
#if defined(HAVE_DLERROR)
	    rb_raise(rb_eFiddleError, "%s", dlerror());
#else
	    rb_raise(rb_eFiddleError, "could not close handle");
#endif
	}
	return INT2NUM(ret);
    }
    rb_raise(rb_eFiddleError, "dlclose() called too many times");

    UNREACHABLE;
}


  








  

    #disable_close    



  

    

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


  



  [ GitHub ]


  

  


# File 'ext/fiddle/handle.c', line 225



static VALUE
rb_fiddle_handle_disable_close(VALUE self)
{
    struct dl_handle *fiddle_handle;

    TypedData_Get_Struct(self, struct dl_handle, &fiddle_handle_data_type, fiddle_handle);
    fiddle_handle->enable_close = 0;
    return Qnil;
}


  








  

    #enable_close    



  

    

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


  



  [ GitHub ]


  

  


# File 'ext/fiddle/handle.c', line 210



static VALUE
rb_fiddle_handle_enable_close(VALUE self)
{
    struct dl_handle *fiddle_handle;

    TypedData_Get_Struct(self, struct dl_handle, &fiddle_handle_data_type, fiddle_handle);
    fiddle_handle->enable_close = 1;
    return Qnil;
}


  








  

    

      #[](name)  
      #sym(name)  
    

  



  

    

Alias for #[].


  





  








  

    #to_i  ⇒ Integer   



  

    

Returns the memory address for this handle.


  



  [ GitHub ]


  

  


# File 'ext/fiddle/handle.c', line 258



static VALUE
rb_fiddle_handle_to_i(VALUE self)
{
    struct dl_handle *fiddle_handle;

    TypedData_Get_Struct(self, struct dl_handle, &fiddle_handle_data_type, fiddle_handle);
    return PTR2NUM(fiddle_handle);
}