Add Function::info() to get information about functions.

Closes #149 and #7.

src/function.rs

@@ -1,10 +1,13 @@
+use std::mem;
 use std::os::raw::c_int;
 use std::ptr;
 
 use crate::error::{Error, Result};
 use crate::ffi;
 use crate::types::LuaRef;
-use crate::util::{assert_stack, check_stack, error_traceback, pop_error, StackGuard};
+use crate::util::{
+    assert_stack, check_stack, error_traceback, pop_error, ptr_to_cstr_bytes, StackGuard,
+};
 use crate::value::{FromLuaMulti, ToLuaMulti};
 
 #[cfg(feature = "async")]
@@ -14,6 +17,18 @@ use {futures_core::future::LocalBoxFuture, futures_util::future};
 #[derive(Clone, Debug)]
 pub struct Function<'lua>(pub(crate) LuaRef<'lua>);
 
+#[derive(Clone, Debug)]
+pub struct FunctionInfo {
+    pub name: Option<Vec<u8>>,
+    pub name_what: Option<Vec<u8>>,
+    pub what: Option<Vec<u8>>,
+    pub source: Option<Vec<u8>>,
+    pub short_src: Option<Vec<u8>>,
+    pub line_defined: i32,
+    #[cfg(not(feature = "luau"))]
+    pub last_line_defined: i32,
+}
+
 impl<'lua> Function<'lua> {
     /// Calls the function, passing `args` as function arguments.
     ///
@@ -209,6 +224,41 @@ impl<'lua> Function<'lua> {
         }
     }
 
+    /// Returns information about the function.
+    ///
+    /// Corresponds to the `>Sn` what mask for [`lua_getinfo`] when applied to the function.
+    ///
+    /// [`lua_getinfo`]: https://www.lua.org/manual/5.4/manual.html#lua_getinfo
+    pub fn info(&self) -> FunctionInfo {
+        let lua = self.0.lua;
+        unsafe {
+            let _sg = StackGuard::new(lua.state);
+            assert_stack(lua.state, 1);
+
+            let mut ar: ffi::lua_Debug = mem::zeroed();
+            lua.push_ref(&self.0);
+            #[cfg(not(feature = "luau"))]
+            let res = ffi::lua_getinfo(lua.state, cstr!(">Sn"), &mut ar);
+            #[cfg(feature = "luau")]
+            let res = ffi::lua_getinfo(lua.state, -1, cstr!("sn"), &mut ar);
+            mlua_assert!(res != 0, "lua_getinfo failed with `>Sn`");
+
+            FunctionInfo {
+                name: ptr_to_cstr_bytes(ar.name).map(|s| s.to_vec()),
+                #[cfg(not(feature = "luau"))]
+                name_what: ptr_to_cstr_bytes(ar.namewhat).map(|s| s.to_vec()),
+                #[cfg(feature = "luau")]
+                name_what: None,
+                what: ptr_to_cstr_bytes(ar.what).map(|s| s.to_vec()),
+                source: ptr_to_cstr_bytes(ar.source).map(|s| s.to_vec()),
+                short_src: ptr_to_cstr_bytes(&ar.short_src as *const _).map(|s| s.to_vec()),
+                line_defined: ar.linedefined as i32,
+                #[cfg(not(feature = "luau"))]
+                last_line_defined: ar.lastlinedefined as i32,
+            }
+        }
+    }
+
     /// Dumps the function as a binary chunk.
     ///
     /// If `strip` is true, the binary representation may not include all debug information

src/hook.rs

@@ -1,11 +1,11 @@
 use std::cell::UnsafeCell;
-use std::ffi::CStr;
 #[cfg(not(feature = "luau"))]
 use std::ops::{BitOr, BitOrAssign};
-use std::os::raw::{c_char, c_int};
+use std::os::raw::c_int;
 
 use crate::ffi::{self, lua_Debug};
 use crate::lua::Lua;
+use crate::util::ptr_to_cstr_bytes;
 
 /// Contains information about currently executing Lua code.
 ///
@@ -77,9 +77,9 @@ impl<'lua> Debug<'lua> {
             );
 
             DebugNames {
-                name: ptr_to_str((*self.ar.get()).name),
+                name: ptr_to_cstr_bytes((*self.ar.get()).name),
                 #[cfg(not(feature = "luau"))]
-                name_what: ptr_to_str((*self.ar.get()).namewhat),
+                name_what: ptr_to_cstr_bytes((*self.ar.get()).namewhat),
                 #[cfg(feature = "luau")]
                 name_what: None,
             }
@@ -101,12 +101,12 @@ impl<'lua> Debug<'lua> {
             );
 
             DebugSource {
-                source: ptr_to_str((*self.ar.get()).source),
-                short_src: ptr_to_str((*self.ar.get()).short_src.as_ptr()),
+                source: ptr_to_cstr_bytes((*self.ar.get()).source),
+                short_src: ptr_to_cstr_bytes((*self.ar.get()).short_src.as_ptr()),
                 line_defined: (*self.ar.get()).linedefined as i32,
                 #[cfg(not(feature = "luau"))]
                 last_line_defined: (*self.ar.get()).lastlinedefined as i32,
-                what: ptr_to_str((*self.ar.get()).what),
+                what: ptr_to_cstr_bytes((*self.ar.get()).what),
             }
         }
     }
@@ -349,11 +349,3 @@ impl BitOrAssign for HookTriggers {
         *self = *self | rhs;
     }
 }
-
-unsafe fn ptr_to_str<'a>(input: *const c_char) -> Option<&'a [u8]> {
-    if input.is_null() {
-        None
-    } else {
-        Some(CStr::from_ptr(input).to_bytes())
-    }
-}

src/lib.rs

@@ -108,7 +108,7 @@ pub use crate::{ffi::lua_CFunction, ffi::lua_State};
 
 pub use crate::chunk::{AsChunk, Chunk, ChunkMode};
 pub use crate::error::{Error, ExternalError, ExternalResult, Result};
-pub use crate::function::Function;
+pub use crate::function::{Function, FunctionInfo};
 pub use crate::hook::{Debug, DebugEvent, DebugNames, DebugSource, DebugStack};
 pub use crate::lua::{GCMode, Lua, LuaOptions};
 pub use crate::multi::Variadic;

src/prelude.rs

@@ -4,13 +4,13 @@
 pub use crate::{
     AnyUserData as LuaAnyUserData, Chunk as LuaChunk, Error as LuaError,
     ExternalError as LuaExternalError, ExternalResult as LuaExternalResult, FromLua, FromLuaMulti,
-    Function as LuaFunction, GCMode as LuaGCMode, Integer as LuaInteger,
-    LightUserData as LuaLightUserData, Lua, LuaOptions, MetaMethod as LuaMetaMethod,
-    MultiValue as LuaMultiValue, Nil as LuaNil, Number as LuaNumber, RegistryKey as LuaRegistryKey,
-    Result as LuaResult, StdLib as LuaStdLib, String as LuaString, Table as LuaTable,
-    TableExt as LuaTableExt, TablePairs as LuaTablePairs, TableSequence as LuaTableSequence,
-    Thread as LuaThread, ThreadStatus as LuaThreadStatus, ToLua, ToLuaMulti,
-    UserData as LuaUserData, UserDataFields as LuaUserDataFields,
+    Function as LuaFunction, FunctionInfo as LuaFunctionInfo, GCMode as LuaGCMode,
+    Integer as LuaInteger, LightUserData as LuaLightUserData, Lua, LuaOptions,
+    MetaMethod as LuaMetaMethod, MultiValue as LuaMultiValue, Nil as LuaNil, Number as LuaNumber,
+    RegistryKey as LuaRegistryKey, Result as LuaResult, StdLib as LuaStdLib, String as LuaString,
+    Table as LuaTable, TableExt as LuaTableExt, TablePairs as LuaTablePairs,
+    TableSequence as LuaTableSequence, Thread as LuaThread, ThreadStatus as LuaThreadStatus, ToLua,
+    ToLuaMulti, UserData as LuaUserData, UserDataFields as LuaUserDataFields,
     UserDataMetatable as LuaUserDataMetatable, UserDataMethods as LuaUserDataMethods,
     Value as LuaValue,
 };

src/util.rs

@@ -992,6 +992,13 @@ pub(crate) unsafe fn get_destructed_userdata_metatable(state: *mut ffi::lua_Stat
     ffi::lua_rawgetp(state, ffi::LUA_REGISTRYINDEX, key);
 }
 
+pub(crate) unsafe fn ptr_to_cstr_bytes<'a>(input: *const c_char) -> Option<&'a [u8]> {
+    if input.is_null() {
+        return None;
+    }
+    Some(CStr::from_ptr(input).to_bytes())
+}
+
 static DESTRUCTED_USERDATA_METATABLE: u8 = 0;
 static ERROR_PRINT_BUFFER_KEY: u8 = 0;
 static USERDATA_METATABLE_INDEX: u8 = 0;

tests/function.rs

@@ -107,3 +107,57 @@ fn test_dump() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_function_info() -> Result<()> {
+    let lua = Lua::new();
+
+    let globals = lua.globals();
+    lua.load(
+        r#"
+        function function1()
+            return function() end
+        end
+    "#,
+    )
+    .set_name("source1")?
+    .exec()?;
+
+    let function1 = globals.get::<_, Function>("function1")?;
+    let function2 = function1.call::<_, Function>(())?;
+    let function3 = lua.create_function(|_, ()| Ok(()))?;
+
+    let function1_info = function1.info();
+    #[cfg(feature = "luau")]
+    assert_eq!(function1_info.name, Some(b"function1".to_vec()));
+    assert_eq!(function1_info.source, Some(b"source1".to_vec()));
+    assert_eq!(function1_info.line_defined, 2);
+    #[cfg(not(feature = "luau"))]
+    assert_eq!(function1_info.last_line_defined, 4);
+    assert_eq!(function1_info.what, Some(b"Lua".to_vec()));
+
+    let function2_info = function2.info();
+    assert_eq!(function2_info.name, None);
+    assert_eq!(function2_info.source, Some(b"source1".to_vec()));
+    assert_eq!(function2_info.line_defined, 3);
+    #[cfg(not(feature = "luau"))]
+    assert_eq!(function2_info.last_line_defined, 3);
+    assert_eq!(function2_info.what, Some(b"Lua".to_vec()));
+
+    let function3_info = function3.info();
+    assert_eq!(function3_info.name, None);
+    assert_eq!(function3_info.source, Some(b"=[C]".to_vec()));
+    assert_eq!(function3_info.line_defined, -1);
+    #[cfg(not(feature = "luau"))]
+    assert_eq!(function3_info.last_line_defined, -1);
+    assert_eq!(function3_info.what, Some(b"C".to_vec()));
+
+    let print_info = globals.get::<_, Function>("print")?.info();
+    #[cfg(feature = "luau")]
+    assert_eq!(print_info.name, Some(b"print".to_vec()));
+    assert_eq!(print_info.source, Some(b"=[C]".to_vec()));
+    assert_eq!(print_info.what, Some(b"C".to_vec()));
+    assert_eq!(print_info.line_defined, -1);
+
+    Ok(())
+}