local io={}



function io.close(file)
return(file or io.output()):close()
end

function io.flush()
return io.output():flush()
end

function io.lines(filename,...)
if filename then
local file,reason=io.open(filename)
if not file then
error(reason,2)
end
local args=table.pack(...)
return function()
local result=table.pack(file:read(table.unpack(args,1,args.n)))
if not result[1]then
if result[2]then
error(result[2],2)
else
file:close()
return nil
end
end
return table.unpack(result,1,result.n)
end
else
return io.input():lines()
end
end

function io.open(path,mode)

local resolved_path=require("shell").resolve(path)
local stream,result=require("filesystem").open(resolved_path,mode)
if stream then
return require("buffer").new(mode,stream)
else
return nil,result
end
end

function io.stream(fd,file,mode)
checkArg(1,fd,'number')
checkArg(2,file,"table","string","nil")
assert(fd>=0,'fd must be >= 0. 0 is input, 1 is stdout, 2 is stderr')
local dio=require("process").info().data.io
if file then
if type(file)=="string"then
file=assert(io.open(file,mode))
end
dio[fd]=file
end
return dio[fd]
end

function io.input(file)
return io.stream(0,file,'r')
end

function io.output(file)
return io.stream(1,file,'w')
end

function io.error(file)
return io.stream(2,file,'w')
end

function io.popen(prog,mode,env)
return require("pipe").popen(prog,mode,env)
end

function io.read(...)
return io.input():read(...)
end

function io.tmpfile()
local name=os.tmpname()
if name then
return io.open(name,"a")
end
end

function io.type(object)
if type(object)=="table"then
if getmetatable(object)=="file"then
if object.stream.handle then
return"file"
else
return"closed file"
end
end
end
return nil
end

function io.write(...)
return io.output():write(...)
end

local dup_mt={__index=function(dfd,key)
local fd_value=dfd.fd[key]
if key~="close"and type(fd_value)~="function"then return fd_value end
return function(self,...)
if key=="close"or self._closed then self._closed=true return end
return fd_value(self.fd,...)
end
end,__newindex=function(dfd,key,value)
dfd.fd[key]=value
end}

function io.dup(fd)
return setmetatable({fd=fd,_closed=false},dup_mt)
end



return io