Update Lua 5.1 FFI bindings (add buffer manipulation, etc)

Author: khvzak

mlua-sys/src/lua51/lauxlib.rs

@@ -107,8 +107,6 @@ pub unsafe fn luaL_optstring(L: *mut lua_State, n: c_int, d: *const c_char) -> *
     luaL_optlstring(L, n, d, ptr::null_mut())
 }
 
-// Deprecated from 5.3: luaL_checkint, luaL_optint, luaL_checklong, luaL_optlong
-
 #[inline(always)]
 pub unsafe fn luaL_typename(L: *mut lua_State, i: c_int) -> *const c_char {
     lua::lua_typename(L, lua::lua_type(L, i))
@@ -138,8 +136,58 @@ pub unsafe fn luaL_getmetatable(L: *mut lua_State, n: *const c_char) {
     lua::lua_getfield_(L, lua::LUA_REGISTRYINDEX, n);
 }
 
-// TODO: luaL_opt
+#[inline(always)]
+pub unsafe fn luaL_opt<T>(
+    L: *mut lua_State,
+    f: unsafe extern "C-unwind" fn(*mut lua_State, c_int) -> T,
+    n: c_int,
+    d: T,
+) -> T {
+    if lua::lua_isnoneornil(L, n) != 0 {
+        d
+    } else {
+        f(L, n)
+    }
+}
 
 //
-// TODO: Generic Buffer Manipulation
+// Generic Buffer Manipulation
 //
+
+// The buffer size used by the lauxlib buffer system.
+// The "16384" workaround is taken from the LuaJIT source code.
+#[rustfmt::skip]
+pub const LUAL_BUFFERSIZE: usize = if libc::BUFSIZ > 16384 { 8192 } else { libc::BUFSIZ as usize };
+
+#[repr(C)]
+pub struct luaL_Buffer {
+    pub p: *mut c_char, // current position in buffer
+    pub lvl: c_int,     // number of strings in the stack
+    pub L: *mut lua_State,
+    pub buffer: [c_char; LUAL_BUFFERSIZE],
+}
+
+#[cfg_attr(all(windows, raw_dylib), link(name = "lua51", kind = "raw-dylib"))]
+unsafe extern "C-unwind" {
+    pub fn luaL_buffinit(L: *mut lua_State, B: *mut luaL_Buffer);
+    pub fn luaL_prepbuffer(B: *mut luaL_Buffer) -> *mut c_char;
+    pub fn luaL_addlstring(B: *mut luaL_Buffer, s: *const c_char, l: usize);
+    pub fn luaL_addstring(B: *mut luaL_Buffer, s: *const c_char);
+    pub fn luaL_addvalue(B: *mut luaL_Buffer);
+    pub fn luaL_pushresult(B: *mut luaL_Buffer);
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addchar(B: *mut luaL_Buffer, c: c_char) {
+    let buffer_end = (*B).buffer.as_mut_ptr().add(LUAL_BUFFERSIZE);
+    if (*B).p >= buffer_end {
+        luaL_prepbuffer(B);
+    }
+    *(*B).p = c;
+    (*B).p = (*B).p.add(1);
+}
+
+#[inline(always)]
+pub unsafe fn luaL_addsize(B: *mut luaL_Buffer, n: usize) {
+    (*B).p = (*B).p.add(n);
+}

mlua-sys/src/lua51/lua.rs

@@ -270,7 +270,10 @@ pub unsafe fn lua_pushcfunction(L: *mut lua_State, f: lua_CFunction) {
     lua_pushcclosure(L, f, 0)
 }
 
-// TODO: lua_strlen
+#[inline(always)]
+pub unsafe fn lua_strlen(L: *mut lua_State, i: c_int) -> usize {
+    lua_objlen(L, i)
+}
 
 #[inline(always)]
 pub unsafe fn lua_isfunction(L: *mut lua_State, n: c_int) -> c_int {