class Fiddle::Handle

The Fiddle::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

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

Constants

DEFAULT

DEFAULT

A predefined pseudo-handle of RTLD_DEFAULT

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

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.

RTLD_GLOBAL

RTLD_GLOBAL

rtld Fiddle::Handle flag.

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

RTLD_LAZY

RTLD_LAZY

rtld Fiddle::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.)

RTLD_NOW

RTLD_NOW

rtld Fiddle::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.

Public Class Methods

sym(name) click to toggle source

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.

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

new(library = nil, flags = Fiddle::RTLD_LAZY | Fiddle::RTLD_GLOBAL) click to toggle source

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.

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");
    }

    rb_secure(2);

#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;
}

sym(name) click to toggle source

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

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

Public Instance Methods

sym(name) click to toggle source

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

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 click to toggle source

Close this handle.

Calling close more than once will raise a Fiddle::DLError exception.

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;
}

close_enabled? click to toggle source

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

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

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;
}

disable_close click to toggle source

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

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 click to toggle source

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

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;
}

sym(name) click to toggle source

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

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);
}

to_i click to toggle source

Returns the memory address for this handle.

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);
}