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-----------------------------------------------------------------------------
-- Little program to download files from URLs
-- LuaSocket sample files
-- Author: Diego Nehab
-----------------------------------------------------------------------------
local socket = require("socket")
local http = require("socket.http")
local ftp = require("socket.ftp")
local url = require("socket.url")
local ltn12 = require("ltn12")
-- formats a number of seconds into human readable form
function nicetime(s)
local l = "s"
if s > 60 then
s = s / 60
l = "m"
if s > 60 then
s = s / 60
l = "h"
if s > 24 then
s = s / 24
l = "d" -- hmmm
end
end
end
if l == "s" then return string.format("%5.0f%s", s, l)
else return string.format("%5.2f%s", s, l) end
end
-- formats a number of bytes into human readable form
function nicesize(b)
local l = "B"
if b > 1024 then
b = b / 1024
l = "KB"
if b > 1024 then
b = b / 1024
l = "MB"
if b > 1024 then
b = b / 1024
l = "GB" -- hmmm
end
end
end
return string.format("%7.2f%2s", b, l)
end
-- returns a string with the current state of the download
local remaining_s = "%s received, %s/s throughput, %2.0f%% done, %s remaining"
local elapsed_s = "%s received, %s/s throughput, %s elapsed "
function gauge(got, delta, size)
local rate = got / delta
if size and size >= 1 then
return string.format(remaining_s, nicesize(got), nicesize(rate),
100*got/size, nicetime((size-got)/rate))
else
return string.format(elapsed_s, nicesize(got),
nicesize(rate), nicetime(delta))
end
end
-- creates a new instance of a receive_cb that saves to disk
-- kind of copied from luasocket's manual callback examples
function stats(size)
local start = socket.gettime()
local last = start
local got = 0
return function(chunk)
-- elapsed time since start
local current = socket.gettime()
if chunk then
-- total bytes received
got = got + string.len(chunk)
-- not enough time for estimate
if current - last > 1 then
io.stderr:write("\r", gauge(got, current - start, size))
io.stderr:flush()
last = current
end
else
-- close up
io.stderr:write("\r", gauge(got, current - start), "\n")
end
return chunk
end
end
-- determines the size of a http file
function gethttpsize(u)
local r, c, h = http.request {method = "HEAD", url = u}
if c == 200 then
return tonumber(h["content-length"])
end
end
-- downloads a file using the http protocol
function getbyhttp(u, file)
local save = ltn12.sink.file(file or io.stdout)
-- only print feedback if output is not stdout
if file then save = ltn12.sink.chain(stats(gethttpsize(u)), save) end
local r, c, h, s = http.request {url = u, sink = save }
if c ~= 200 then io.stderr:write(s or c, "\n") end
end
-- downloads a file using the ftp protocol
function getbyftp(u, file)
local save = ltn12.sink.file(file or io.stdout)
-- only print feedback if output is not stdout
-- and we don't know how big the file is
if file then save = ltn12.sink.chain(stats(), save) end
local gett = url.parse(u)
gett.sink = save
gett.type = "i"
local ret, err = ftp.get(gett)
if err then print(err) end
end
-- determines the scheme
function getscheme(u)
-- this is an heuristic to solve a common invalid url poblem
if not string.find(u, "//") then u = "//" .. u end
local parsed = url.parse(u, {scheme = "http"})
return parsed.scheme
end
-- gets a file either by http or ftp, saving as <name>
function get(u, name)
local fout = name and io.open(name, "wb")
local scheme = getscheme(u)
if scheme == "ftp" then getbyftp(u, fout)
elseif scheme == "http" then getbyhttp(u, fout)
else print("unknown scheme" .. scheme) end
end
-- main program
arg = arg or {}
if #arg < 1 then
io.write("Usage:\n lua get.lua <remote-url> [<local-file>]\n")
os.exit(1)
else get(arg[1], arg[2]) end
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