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|
{- Url downloading.
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Utility.Url (
URLString,
exists,
canDownload,
download,
get
) where
import Control.Applicative
import qualified Network.Browser as Browser
import Network.HTTP
import Network.URI
import Utility.SafeCommand
import Utility.Path
type URLString = String
{- Checks that an url exists and could be successfully downloaded. -}
exists :: URLString -> IO Bool
exists url =
case parseURI url of
Nothing -> return False
Just u -> do
r <- request u HEAD
case rspCode r of
(2,_,_) -> return True
_ -> return False
canDownload :: IO Bool
canDownload = (||) <$> inPath "wget" <*> inPath "curl"
{- Used to download large files, such as the contents of keys.
-
- Uses wget or curl program for its progress bar. (Wget has a better one,
- so is preferred.) Which program to use is determined at run time; it
- would not be appropriate to test at configure time and build support
- for only one in.
-}
download :: URLString -> [CommandParam] -> FilePath -> IO Bool
download url options file = do
e <- inPath "wget"
if e
then
go "wget" [Params "-c -O", File file, File url]
else
-- Uses the -# progress display, because the normal
-- one is very confusing when resuming, showing
-- the remainder to download as the whole file,
-- and not indicating how much percent was
-- downloaded before the resume.
go "curl" [Params "-L -C - -# -o", File file, File url]
where
go cmd opts = boolSystem cmd (options++opts)
{- Downloads a small file. -}
get :: URLString -> IO String
get url =
case parseURI url of
Nothing -> error "url parse error"
Just u -> do
r <- request u GET
case rspCode r of
(2,_,_) -> return $ rspBody r
_ -> error $ rspReason r
{- Makes a http request of an url. For example, HEAD can be used to
- check if the url exists, or GET used to get the url content (best for
- small urls). -}
request :: URI -> RequestMethod -> IO (Response String)
request url requesttype = Browser.browse $ do
Browser.setErrHandler ignore
Browser.setOutHandler ignore
Browser.setAllowRedirects True
snd <$> Browser.request (mkRequest requesttype url :: Request_String)
where
ignore = const $ return ()
|
