Module io_lib 

Standard I/O library — io.* functions and file:* methods.

C source: src/liolib.c (841 lines, ~35 functions).

PORT NOTE: Filesystem and process access is host-provided. Regular files use GlobalState::file_open_hook, io.popen uses GlobalState::popen_hook, and stdout/stderr use output hooks when installed. The native CLI provides hooks backed by std::fs, std::process, and std::io; sandboxed and WASM hosts can leave those capabilities absent.

PORT NOTE: Rust’s borrow checker prevents holding &mut dyn LuaFileOps (extracted from userdata) and &mut LuaState simultaneously. The affected functions (io_read, f_read, io_write, f_write, io_flush, f_flush, f_seek, f_setvbuf, get_io_file) are marked with TODO(port): borrow split. Phase B must restructure g_read/g_write to take a StackIdx rather than a raw &mut dyn LuaFileOps, and use RefCell inside LStream for interior mutability, or extract the file handle via a separate borrow scope.

Structs

LStream

Lua file handle stored as the typed payload of a LuaUserData.

Enums

BufMode

Buffering mode for file:setvbuf. C: {_IONBF, _IOFBF, _IOLBF}.

SeekWhence

Seek anchor for file:seek. C: {SEEK_SET, SEEK_CUR, SEEK_END}.

StdFileKind

Which standard stream to wrap in create_std_file.

Constants

FILE_METAMETHODS

File-handle metamethods. C: static const luaL_Reg metameth[].

FILE_METHODS

file:* instance methods. C: static const luaL_Reg meth[].

IO_LIB

io.* module functions. C: static const luaL_Reg iolib[].

LUA_FILE_HANDLE

Name of the file-handle metatable in the Lua registry. C: LUA_FILEHANDLE.

Traits

LuaFileOps

Capabilities required by the io library from an OS file handle.

Functions

f_flush

file:flush(). C: f_flush.

f_lines

file:lines(...). C: f_lines.

f_read

file:read(...). C: f_read.

f_seek

file:seek([whence [, offset]]). C: f_seek.

f_setvbuf

file:setvbuf(mode [, size]). C: f_setvbuf.

f_write

file:write(...). C: f_write.

io_close

io.close([file]). C: io_close.

io_flush

io.flush(). C: io_flush.

io_input

io.input([file]). C: io_input.

io_lines

io.lines([filename, ...]). C: io_lines.

io_open

io.open(filename [, mode]). C: io_open.

io_output

io.output([file]). C: io_output.

io_popen

io.popen(filename [, mode]). C: io_popen.

io_read

io.read(...). C: io_read.

io_tmpfile

io.tmpfile(). C: io_tmpfile.

io_type

io.type(x) — return "file", "closed file", or false. C: io_type.

io_write

io.write(...). C: io_write.

luaopen_io

Open the io library and return 1 (the library table). C: luaopen_io.