95 lines
2.8 KiB
Haskell
95 lines
2.8 KiB
Haskell
{- Url downloading.
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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{-# LANGUAGE CPP #-}
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module Utility.Url (
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URLString,
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check,
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exists,
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download,
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get
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) where
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import Common
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import Network.URI
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type URLString = String
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type Headers = [String]
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{- Checks that an url exists and could be successfully downloaded,
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- also checking that its size, if available, matches a specified size. -}
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check :: URLString -> Headers -> Maybe Integer -> IO Bool
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check url headers expected_size = handle <$> exists url headers
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where
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handle (False, _) = False
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handle (True, Nothing) = True
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handle (True, s) = expected_size == s
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{- Checks that an url exists and could be successfully downloaded,
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- also returning its size if available. -}
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exists :: URLString -> Headers -> IO (Bool, Maybe Integer)
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exists url headers = case parseURI url of
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Just u
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| uriScheme u == "file:" -> do
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s <- catchMaybeIO $ getFileStatus (uriPath u)
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case s of
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Just stat -> return (True, Just $ fromIntegral $ fileSize stat)
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Nothing -> dne
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| otherwise -> do
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output <- readProcess "curl" curlparams
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case lastMaybe (lines output) of
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Just ('2':_:_) -> return (True, extractsize output)
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_ -> dne
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Nothing -> dne
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where
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dne = return (False, Nothing)
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curlparams =
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[ "-s"
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, "--head"
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, "-L"
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, url
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, "-w", "%{http_code}"
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] ++ concatMap (\h -> ["-H", h]) headers
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extractsize s = case lastMaybe $ filter ("Content-Length:" `isPrefixOf`) (lines s) of
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Just l -> case lastMaybe $ words l of
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Just sz -> readish sz
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_ -> Nothing
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_ -> Nothing
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{- Used to download large files, such as the contents of keys.
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-
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- Uses wget or curl program for its progress bar. (Wget has a better one,
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- so is preferred.) Which program to use is determined at run time; it
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- would not be appropriate to test at configure time and build support
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- for only one in.
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-
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- Curl is always used for file:// urls, as wget does not support them.
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-}
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download :: URLString -> Headers -> [CommandParam] -> FilePath -> IO Bool
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download url headers options file
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| "file://" `isPrefixOf` url = curl
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| otherwise = ifM (inPath "wget") (wget , curl)
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where
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headerparams = map (\h -> Param $ "--header=" ++ h) headers
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wget = go "wget" $ headerparams ++ [Params "-c -O"]
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{- Uses the -# progress display, because the normal
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- one is very confusing when resuming, showing
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- the remainder to download as the whole file,
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- and not indicating how much percent was
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- downloaded before the resume. -}
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curl = go "curl" $ headerparams ++ [Params "-L -C - -# -o"]
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go cmd opts = boolSystem cmd $
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options++opts++[File file, File url]
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{- Downloads a small file. -}
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get :: URLString -> Headers -> IO String
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get url headers = readProcess "curl" $
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["-s", "-L", url] ++ concatMap (\h -> ["-H", h]) headers
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