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R_LANG(3)		     Library Functions Manual		       R_LANG(3)

NAME
     r_lang -- Scripting language support library for radare2

SYNOPSIS
     Use this section to show the public header and the basic include needed to
     build against the r_lang API; it gives the minimal compile-time view of the
     library.

     #include <r_lang.h>

DESCRIPTION
     Readers will find here a concise overview of the goals and structure of the
     r_lang  module:  a  plugin-driven	runtime  that  lets radare2 host and run
     scripts and REPLs from multiple languages.

     The r_lang library provides scripting language support for radare2  through
     a	plugin-based  system.	It  allows executing code in various programming
     languages within the radare2 environment, enabling automation, custom  com-
     mands, and extensions.

     At  the  heart of the API is struct r_lang_t, which manages loaded language
     plugins, user pointers and execution  sessions.   Language  implementations
     register  a struct r_lang_plugin_t, supplying callbacks for initialization,
     running code, running files, interactive prompts and cleanup.

INITIALIZATION
     This section documents how to create and destroy an r_lang handle	and  how
     to  associate runtime state (typically a pointer to an RCore instance) with
     it.

     Create a new language instance:

	   RLang *lang = r_lang_new();

     Set user pointer (usually RCore):

	   r_lang_set_user_ptr(lang, core);

     Free when done:

	   r_lang_free(lang);

EXECUTION
     Use these calls to select a language plugin, execute code buffers,  or  in-
     voke  script  files. The typical host (radare2) selects a plugin then calls
     one of the run helpers shown below.

     Select a language:

	   r_lang_use(lang, "qjs"); // QuickJS JavaScript

     Execute code string:

	   const char *code = "console.log('Hello from r2!');";
	   r_lang_run_string(lang, code);

     Execute code with length:

	   r_lang_run(lang, code, strlen(code));

     Execute script file:

	   r_lang_run_file(lang, "script.js");

INTERACTIVE MODE
     Interactive features (REPLs) are implemented per-plugin and can be  entered
     via  the  generic	prompt helper; this is the place to learn how to start a
     language REPL from the embedding application.

     Start interactive prompt:

	   r_lang_prompt(lang); // Interactive REPL

ARGUMENTS
     Scripts that expect positional arguments receive them via the argv helpers;
     the API lets hosts set argc/argv before invoking a file or an  entry  call-
     back.

     Set command-line arguments for scripts:

	   char *argv[] = {"script.js", "arg1", "arg2"};
	   r_lang_set_argv(lang, 3, argv);

DEFINITIONS
     Use the definitions API to expose host pointers and typed variables to lan-
     guage  runtimes;  the  host can add and remove named definitions visible to
     scripts.

     Define variables accessible from scripts:

	   int value = 42;
	   r_lang_define(lang, "int", "my_var", &value);

     Remove definition:

	   r_lang_undef(lang, "my_var");

LANGUAGES
     This section highlights notable, supported  language  entry  points  rather
     than  exhaustively  listing every plugin. It focuses on the two integration
     styles commonly used by radare2: an embedded VM and native C  plugin/script
     support.

     *	 JavaScript:  a  native  QuickJS  (`qjs`) plugin is available and is the
	 canonical embedded scripting VM inside  radare2.  Use	`r_lang_use(...,
	 "qjs")` to select it and `r_lang_run_string` / `r_lang_run_file` to ex-
	 ecute code.

     *	 C  scripts:  the  C  plugin compiles a `.c` file into a shared library,
	 opens the resulting library, resolves an `entry` symbol  and  calls  it
	 with  the  current `RCore *` (stored in `r_lang->user`) and the config-
	 ured `argc, argv`. The C  entry  must	have  the  signature  `void  en-
	 try(RCore *core, int argc, const char **argv)`.

EXAMPLES
     The examples below show common usage patterns observed in the radare2 core:
     invoking  QuickJS	code,  running	inline expressions via the `#!` hashbang
     helper, and how C scripts are compiled and invoked with  the  host  `RCore`
     pointer.

     Execute JavaScript code:

	   #include <r_lang.h>

	   int main() {
	       RLang *lang = r_lang_new();
	       r_lang_use(lang, "qjs");

	       const char *js_code = R"js(
		   console.log("Hello from JavaScript!");
		   var addr = 0x1000;
		   console.log("Address: 0x" + addr.toString(16));
	       )js";

	       r_lang_run_string(lang, js_code);
	       r_lang_free(lang);
	       return 0;
	   }

     Define and use variables:

	   RLang *lang = r_lang_new();
	   int my_int = 12345;
	   r_lang_define(lang, "int", "global_var", &my_int);

	   r_lang_use(lang, "qjs");
	   r_lang_run_string(lang, "console.log('Value: ' + global_var);");

	   r_lang_free(lang);

     Execute script file:

	   r_lang_run_file(lang, "script.js");

     Hashbang	 and	`-e`	usage	 (used	  by   the   `#!`   command   in
     `libr/core/cmd_hash.inc.c`):

	   // the command handler implemented in libr/core/cmd_hash.inc.c parses `#!` lines
	   // and: selects the requested plugin (r_lang_get_by_name/r_lang_use_plugin),
	   // sets argv via r_lang_set_argv when file arguments are present, and either
	   // runs a file with r_lang_run_file or runs an expression with r_lang_run_string
	   // when `-e` is passed; expressions prefixed with `base64:` are decoded first.

     C script example (how the C plugin runs code):

	   /* example.c */
	   #include <r_core.h>

	   void entry(RCore *core, int argc, const char **argv) {
	       char *s = r_core_cmd_str (core, "?E hello world");
	       printf("%s", s);
	       free (s);
	   }

	   /* The C plugin will compile this file to a shared library and call `entry` with
	      the host RCore pointer (r_lang->user) and any argv configured via
	      r_lang_set_argv(). */

SEE ALSO
     r_core(3), r_util(3)

FreeBSD ports 15.quarterly     September 21, 2025		       R_LANG(3)

Want to link to this manual page? Use this URL:
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