1 files changed, 118 insertions, 0 deletions
diff --git a/src/liolib.js b/src/liolib.js
index 22dc2e8..2136755 100644
--- a/src/liolib.js
+++ b/src/liolib.js
@@ -1,12 +1,107 @@
 "use strict";
 
+const assert  = require('assert');
+const fs      = require('fs');
+
 const lua     = require('./lua.js');
 const lauxlib = require('./lauxlib.js');
 
+const IO_PREFIX = "_IO_";
+const IOPREF_LEN = IO_PREFIX.length;
+const IO_INPUT = lua.to_luastring(IO_PREFIX + "input");
+const IO_OUTPUT = lua.to_luastring(IO_PREFIX + "output");
+
+const tolstream = function(L) {
+    return lauxlib.luaL_checkudata(L, 1, lauxlib.LUA_FILEHANDLE);
+};
+
+const isclosed = function(p) {
+    return p.closef === null;
+};
+
+const f_tostring = function(L) {
+    let p = tolstream(L);
+    if (isclosed(p))
+        lua.lua_pushliteral(L, "file (closed)");
+    else
+        lua.lua_pushstring(L, lua.to_luastring(`file (${p.f.toString()})`));
+    return 1;
+};
+
+const tofile = function(L) {
+    let p = tolstream(L);
+    if (isclosed(p))
+        lauxlib.luaL_error(L, "attempt to use a closed file");
+    assert(p.f);
+    return p.f;
+};
+
+const newprefile = function(L) {
+    let p = lua.lua_newuserdata(L);
+    p.f = null;
+    p.closef = null;
+    lauxlib.luaL_setmetatable(L, lauxlib.LUA_FILEHANDLE);
+    return p;
+};
+
+const aux_close = function(L) {
+    let p = tolstream(L);
+    let cf = p.closef;
+    p.closef = null;
+    return cf(L);
+};
+
+const io_close = function(L) {
+    if (lua.lua_isnone(L, 1))  /* no argument? */
+        lua.lua_getfield(L, lua.LUA_REGISTRYINDEX, IO_OUTPUT);  /* use standard output */
+    tofile(L);  /* make sure argument is an open stream */
+    return aux_close(L);
+};
+
+const getiofile = function(L, findex) {
+    lua.lua_getfield(L, lua.LUA_REGISTRYINDEX, findex);
+    let p = lua.lua_touserdata(L, -1);
+    if (isclosed(p))
+        lauxlib.luaL_error(L, lua.to_luastring(`standard ${lua.to_jsstring(findex.slice(IOPREF_LEN))} file is closed`));
+    return p.f;
+};
+
+const g_write = function(L, f, arg) {
+    let nargs = lua.lua_gettop(L) - arg;
+    let status = true;
+    let err;
+    for (; nargs--; arg++) {
+        let s = lauxlib.luaL_checklstring(L, arg);
+        try {
+            status = status && (fs.writeSync(f.fd, Uint8Array.from(s)) === s.length);
+        } catch (e) {
+            status = false;
+            err = e;
+        }
+    }
+    if (status) return 1;  /* file handle already on stack top */
+    else return lauxlib.luaL_fileresult(L, status, null, err);
+};
+
+const io_write = function(L) {
+    return g_write(L, getiofile(L, IO_OUTPUT), 1);
+};
+
+const f_write = function(L) {
+    let f = tofile(L);
+    lua.lua_pushvalue(L, 1); /* push file at the stack top (to be returned) */
+    return g_write(L, f, 2);
+};
+
 const iolib = {
+    "close": io_close,
+    "write": io_write
 };
 
 const flib = {
+    "close": io_close,
+    "write": f_write,
+    "__tostring": f_tostring
 };
 
 const createmeta = function(L) {
@@ -17,9 +112,32 @@ const createmeta = function(L) {
     lua.lua_pop(L, 1);  /* pop new metatable */
 };
 
+const io_noclose = function(L) {
+    let p = tolstream(L);
+    p.closef = io_noclose;
+    lua.lua_pushnil(L);
+    lua.lua_pushliteral(L, "cannot close standard file");
+    return 2;
+};
+
+const createstdfile = function(L, f, k, fname) {
+    let p = newprefile(L);
+    p.f = f;
+    p.closef = io_noclose;
+    if (k !== null) {
+        lua.lua_pushvalue(L, -1);
+        lua.lua_setfield(L, lua.LUA_REGISTRYINDEX, k);  /* add file to registry */
+    }
+    lua.lua_setfield(L, -2, fname);  /* add file to module */
+};
+
 const luaopen_io = function(L) {
     lauxlib.luaL_newlib(L, iolib);
     createmeta(L);
+    /* create (and set) default files */
+    createstdfile(L, process.stdin, IO_INPUT, lua.to_luastring("stdin"));
+    createstdfile(L, process.stdout, IO_OUTPUT, lua.to_luastring("stdout"));
+    createstdfile(L, process.stderr, null, lua.to_luastring("stderr"));
     return 1;
 };