Class: Fiddle::Handle (Ruby 2.7.2)
Description: Class : Fiddle::Handle - Ruby 2.7.2

### Home Classes Methods

### In Files

- fiddle/closure.c

### Parent

Object

### Methods

- ::[]
- ::new
- ::sym
- #[]
- #close
- #close_enabled?
- #disable_close
- #enable_close
- #sym
- #to_i

### Class/Module Index

Quicksearch

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- Fiddle::Closure
- Fiddle::Closure::BlockCaller
- Fiddle::CompositeHandler
- Fiddle::DLError
- Fiddle::Function
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# 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

or

    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

  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 : 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;
    }

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);
    }