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
or
strcpy_addr = @handle.sym('strcpy')
=> 140062278451968
A predefined pseudo-handle of RTLD_NEXT
Which will find the next occurrence of a function in the search order after the current library.
A predefined pseudo-handle of RTLD_DEFAULT
Which will find the first occurrence of the desired symbol using the default library search order
rtld Fiddle::Handle flag.
The symbols defined by this library will be made available for symbol resolution of subsequently loaded libraries.
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 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.
static VALUE
rb_fiddle_handle_s_sym(VALUE self, VALUE sym)
{
return fiddle_handle_sym(RTLD_NEXT, 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.
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 : StringValueCStr(lib);
cflag = RTLD_LAZY | RTLD_GLOBAL;
break;
case 2:
clib = NIL_P(lib) ? NULL : StringValueCStr(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;
}
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_s_sym(VALUE self, VALUE sym)
{
return fiddle_handle_sym(RTLD_NEXT, sym);
}
Get the address as an Integer for the function named name.
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 this handle.
Calling close more than once will raise a Fiddle::DLError exception.
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;
}
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_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;
}
Disable 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;
}
Enable a call to dlclose() when this handle is garbage collected.
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);
}
Get the address as an Integer for the function named name.
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);
}
Returns the memory address for this handle.