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