module Fiddle

A libffi wrapper for Ruby.

Description¶ ↑

Fiddle is an extension to translate a foreign function interface (FFI) with ruby.

It wraps libffi, a popular C library which provides a portable interface that allows code written in one language to call code written in another language.

Example¶ ↑

Here we will use Fiddle::Function to wrap floor(3) from libm

require 'fiddle'

libm = Fiddle.dlopen('/lib/libm.so.6')

floor = Fiddle::Function.new(
  libm['floor'],
  [Fiddle::TYPE_DOUBLE],
  Fiddle::TYPE_DOUBLE
)

puts floor.call(3.14159) #=> 3.0

Constants

ALIGN_CHAR

ALIGN_CHAR

The alignment size of a char

ALIGN_DOUBLE

ALIGN_DOUBLE

The alignment size of a double

ALIGN_FLOAT

ALIGN_FLOAT

The alignment size of a float

ALIGN_INT

ALIGN_INT

The alignment size of an int

ALIGN_INTPTR_T

ALIGN_INTPTR_T

The alignment size of a intptr_t

ALIGN_LONG

ALIGN_LONG

The alignment size of a long

ALIGN_LONG_LONG

ALIGN_LONG_LONG

The alignment size of a long long

ALIGN_PTRDIFF_T

ALIGN_PTRDIFF_T

The alignment size of a ptrdiff_t

ALIGN_SHORT

ALIGN_SHORT

The alignment size of a short

ALIGN_SIZE_T

ALIGN_SIZE_T

The alignment size of a size_t

ALIGN_SSIZE_T

ALIGN_SSIZE_T

The alignment size of a ssize_t

ALIGN_UINTPTR_T

ALIGN_UINTPTR_T

The alignment size of a uintptr_t

ALIGN_VOIDP

ALIGN_VOIDP

The alignment size of a void*

BUILD_RUBY_PLATFORM

BUILD_RUBY_PLATFORM

Platform built against (i.e. “x86_64-linux”, etc.)

Public Class Methods

dlopen(library) → Fiddle::Handle click to toggle source

Creates a new handler that opens library, and returns an instance of Fiddle::Handle.

If nil is given for the library, Fiddle::Handle::DEFAULT is used, which is the equivalent to RTLD_DEFAULT. See man 3 dlopen for more.

lib = Fiddle.dlopen(nil)

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.

See Fiddle::Handle.new for more.

# File fiddle/lib/fiddle.rb, line 46
def dlopen library
  Fiddle::Handle.new library
end

dlunwrap(addr) click to toggle source

Returns the hexadecimal representation of a memory pointer address addr

Example:

lib = Fiddle.dlopen('/lib64/libc-2.15.so')
=> #<Fiddle::Handle:0x00000001342460>

lib['strcpy'].to_s(16)
=> "7f59de6dd240"

Fiddle.dlunwrap(Fiddle.dlwrap(lib['strcpy'].to_s(16)))
=> "7f59de6dd240"

VALUE
rb_fiddle_ptr2value(VALUE self, VALUE addr)
{
    return (VALUE)NUM2PTR(addr);
}

dlwrap(val) click to toggle source

Returns a memory pointer of a function’s hexadecimal address location val

Example:

lib = Fiddle.dlopen('/lib64/libc-2.15.so')
=> #<Fiddle::Handle:0x00000001342460>

Fiddle.dlwrap(lib['strcpy'].to_s(16))
=> 25522520

static VALUE
rb_fiddle_value2ptr(VALUE self, VALUE val)
{
    return PTR2NUM((void*)val);
}

free(addr) click to toggle source

Free the memory at address addr

VALUE
rb_fiddle_free(VALUE self, VALUE addr)
{
    void *ptr = NUM2PTR(addr);

    ruby_xfree(ptr);
    return Qnil;
}

last_error() click to toggle source

Returns the last Error of the current executing Thread or nil if none

# File fiddle/lib/fiddle.rb, line 21
def self.last_error
  Thread.current[:__FIDDLE_LAST_ERROR__]
end

last_error=(error) click to toggle source

Sets the last Error of the current executing Thread to error

# File fiddle/lib/fiddle.rb, line 26
def self.last_error= error
  Thread.current[:__DL2_LAST_ERROR__] = error
  Thread.current[:__FIDDLE_LAST_ERROR__] = error
end

malloc(size) click to toggle source

Allocate size bytes of memory and return the integer memory address for the allocated memory.

static VALUE
rb_fiddle_malloc(VALUE self, VALUE size)
{
    void *ptr;

    ptr = (void*)ruby_xmalloc(NUM2SIZET(size));
    return PTR2NUM(ptr);
}

realloc(addr, size) click to toggle source

Change the size of the memory allocated at the memory location addr to size bytes. Returns the memory address of the reallocated memory, which may be different than the address passed in.

static VALUE
rb_fiddle_realloc(VALUE self, VALUE addr, VALUE size)
{
    void *ptr = NUM2PTR(addr);

    ptr = (void*)ruby_xrealloc(ptr, NUM2SIZET(size));
    return PTR2NUM(ptr);
}

win32_last_error() click to toggle source

Returns the last win32 Error of the current executing Thread or nil if none

# File fiddle/lib/fiddle.rb, line 10
def self.win32_last_error
  Thread.current[:__FIDDLE_WIN32_LAST_ERROR__]
end

win32_last_error=(error) click to toggle source

Sets the last win32 Error of the current executing Thread to error

# File fiddle/lib/fiddle.rb, line 15
def self.win32_last_error= error
  Thread.current[:__FIDDLE_WIN32_LAST_ERROR__] = error
end

Private Instance Methods

dlopen(library) → Fiddle::Handle click to toggle source

Creates a new handler that opens library, and returns an instance of Fiddle::Handle.

If nil is given for the library, Fiddle::Handle::DEFAULT is used, which is the equivalent to RTLD_DEFAULT. See man 3 dlopen for more.

lib = Fiddle.dlopen(nil)

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.

See Fiddle::Handle.new for more.

# File fiddle/lib/fiddle.rb, line 46
def dlopen library
  Fiddle::Handle.new library
end