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|
{- Url downloading.
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Utility.Url (
URLString,
check,
exists,
download,
get
) where
import Common
import Network.URI
type URLString = String
type Headers = [String]
{- Checks that an url exists and could be successfully downloaded,
- also checking that its size, if available, matches a specified size. -}
check :: URLString -> Headers -> Maybe Integer -> IO Bool
check url headers expected_size = handle <$> exists url headers
where
handle (False, _) = False
handle (True, Nothing) = True
handle (True, s) = expected_size == s
{- Checks that an url exists and could be successfully downloaded,
- also returning its size if available. -}
exists :: URLString -> Headers -> IO (Bool, Maybe Integer)
exists url headers = case parseURI url of
Just u
| uriScheme u == "file:" -> do
s <- catchMaybeIO $ getFileStatus (uriPath u)
case s of
Just stat -> return (True, Just $ fromIntegral $ fileSize stat)
Nothing -> dne
| otherwise -> do
output <- readProcess "curl" curlparams
case lastMaybe (lines output) of
Just ('2':_:_) -> return (True, extractsize output)
_ -> dne
Nothing -> dne
where
dne = return (False, Nothing)
curlparams =
[ "-s"
, "--head"
, "-L"
, url
, "-w", "%{http_code}"
] ++ concatMap (\h -> ["-H", h]) headers
extractsize s = case lastMaybe $ filter ("Content-Length:" `isPrefixOf`) (lines s) of
Just l -> case lastMaybe $ words l of
Just sz -> readish sz
_ -> Nothing
_ -> Nothing
{- 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.
-
- Curl is always used for file:// urls, as wget does not support them.
-}
download :: URLString -> Headers -> [CommandParam] -> FilePath -> IO Bool
download url headers options file
| "file://" `isPrefixOf` url = curl
| otherwise = ifM (inPath "wget") (wget , curl)
where
headerparams = map (\h -> Param $ "--header=" ++ h) headers
wget = go "wget" $ headerparams ++ [Params "-c -O"]
{- 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. -}
curl = go "curl" $ headerparams ++ [Params "-L -C - -# -o"]
go cmd opts = boolSystem cmd $
options++opts++[File file, File url]
{- Downloads a small file. -}
get :: URLString -> Headers -> IO String
get url headers = readProcess "curl" $
["-s", "-L", url] ++ concatMap (\h -> ["-H", h]) headers
|
