lights FAQ Forum

Portable OS APIs


standard I/O

local stdio = require'stdio'

Rationale: Even though standard file objects in LuaJIT are FILE* handles, there's no API to work with cdata buffers on those handles and avoid creating Lua strings. This module fixes that.


stdio.reopen(f, path[, mode]) -> true | nil,err,errno close file/open a different file
i/o, [buf], sz) -> szread | nil,err,errno read more data from the file
stdio.write(f, s[, sz]) -> true | nil,err,errno write more data to the file
stdio.avail(f) -> sz | nil,err how many bytes to EOF
stdio.readfile(f[, 't']) -> data, sz read entire file to a buffer
stdio.writefile(f, s[, sz[, 't']]) -> true | nil,err,errno write a string or cdata to a file
i/o streams
stdio.reader(f) -> read(buf, sz) -> readsz make a reader function
stdio.writer(f) -> write(s[, sz]) make a writer function
file descriptors
stdio.fileno(f) -> n | nil,err,errno get fileno of file
stdio.dopen(fileno) -> f | nil,err,errno open file based on fileno
stdio.close(f) -> true | nil,err,errno close file
error reporting
stdio.error(f) -> errno errno of last operation on file
stdio.clearerr(f) clear last errno
stdio.strerror(errno) -> s | nil errno to string


io-opened file objects are compatible with cdata FILE* objects but they're not fully equivalent. To be safe, always use f:close() instead of io.close() or stdio.close().

Don't forget to specify the 'b' (binary) flag when opening files!

Reading and writing zero bytes is allowed (negative sizes raise an error).

Reading into a nil buffer is allowed (it just seeks).

The "i/o stream" functions are unprotected (i.e. they raise errors) and can thus be used with codecs like bmp directly.

Files larger than 4 Petabytes are not supported.

Last updated: 24 days ago | Edit on GitHub

Pkg type:Lua+ffi
Version: dev-9-g1489acf
Last commit:
License: PD
Requires: luajit 
Required by: nanojpeg  obj_parser  sg