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| author | Matthew Pickering <matthewtpickering@gmail.com> | 2015-01-19 12:00:29 +0000 |
|---|---|---|
| committer | Matthew Pickering <matthewtpickering@gmail.com> | 2015-02-18 20:11:08 +0000 |
| commit | bf8667660d027f2aac7256e25b904170302d440f (patch) | |
| tree | 6d14991bc884d2594dfd0f6302e270141a05bd27 | |
| parent | 9cd0bdb41a2c14e0f28e5ab179b0da73a0b8ba78 (diff) | |
| download | pandoc-bf8667660d027f2aac7256e25b904170302d440f.tar.gz | |
Remove landmine from ImageSize
| -rw-r--r-- | src/Text/Pandoc/ImageSize.hs | 67 |
1 files changed, 37 insertions, 30 deletions
diff --git a/src/Text/Pandoc/ImageSize.hs b/src/Text/Pandoc/ImageSize.hs index 68b34dcf3..963057b6f 100644 --- a/src/Text/Pandoc/ImageSize.hs +++ b/src/Text/Pandoc/ImageSize.hs @@ -1,4 +1,5 @@ {-# LANGUAGE OverloadedStrings, ScopedTypeVariables #-} +{-# OPTIONS_GHC -fno-warn-type-defaults #-} {- Copyright (C) 2011-2014 John MacFarlane <jgm@berkeley.edu> @@ -40,6 +41,10 @@ import Data.Binary import Data.Binary.Get import Text.Pandoc.Shared (safeRead) import qualified Data.Map as M +import Text.Pandoc.Compat.Except +import Text.Pandoc.Error +import Control.Monad.Trans +import Data.Maybe (fromMaybe) -- quick and dirty functions to get image sizes -- algorithms borrowed from wwwis.pl @@ -64,7 +69,7 @@ imageType img = case B.take 4 img of "%!PS" | (B.take 4 $ B.drop 1 $ B.dropWhile (/=' ') img) == "EPSF" -> return Eps - _ -> fail "Unknown image type" + _ -> (hush . Left) "Unknown image type" imageSize :: ByteString -> Maybe ImageSize imageSize img = do @@ -114,7 +119,7 @@ pngSize img = do ([w1,w2,w3,w4,h1,h2,h3,h4] :: [Integer]) -> return ((shift w1 24) + (shift w2 16) + (shift w3 8) + w4, (shift h1 24) + (shift h2 16) + (shift h3 8) + h4) - _ -> fail "PNG parse error" + _ -> (hush . Left) "PNG parse error" let (dpix, dpiy) = findpHYs rest'' return $ ImageSize { pxX = x, pxY = y, dpiX = dpix, dpiY = dpiy } @@ -143,7 +148,7 @@ gifSize img = do dpiX = 72, dpiY = 72 } - _ -> fail "GIF parse error" + _ -> (hush . Left) "GIF parse error" jpegSize :: ByteString -> Maybe ImageSize jpegSize img = do @@ -174,36 +179,37 @@ findJfifSize bs = do Just (c,bs'') | c >= '\xc0' && c <= '\xc3' -> do case map fromIntegral $ unpack $ B.take 4 $ B.drop 3 bs'' of [h1,h2,w1,w2] -> return (shift w1 8 + w2, shift h1 8 + h2) - _ -> fail "JPEG parse error" + _ -> (hush . Left) "JPEG parse error" Just (_,bs'') -> do case map fromIntegral $ unpack $ B.take 2 bs'' of [c1,c2] -> do let len = shift c1 8 + c2 -- skip variables findJfifSize $ B.drop len bs'' - _ -> fail "JPEG parse error" - Nothing -> fail "Did not find length record" + _ -> (hush . Left) "JPEG parse error" + Nothing -> (hush . Left) "Did not find length record" exifSize :: ByteString -> Maybe ImageSize -exifSize bs = runGet (Just <$> exifHeader bl) bl +exifSize bs = hush . runGet header $ bl where bl = BL.fromChunks [bs] + header = runExceptT $ exifHeader bl -- NOTE: It would be nicer to do -- runGet ((Just <$> exifHeader) <|> return Nothing) -- which would prevent pandoc from raising an error when an exif header can't -- be parsed. But we only get an Alternative instance for Get in binary 0.6, -- and binary 0.5 ships with ghc 7.6. -exifHeader :: BL.ByteString -> Get ImageSize +exifHeader :: BL.ByteString -> ExceptT String Get ImageSize exifHeader hdr = do - _app1DataSize <- getWord16be - exifHdr <- getWord32be - unless (exifHdr == 0x45786966) $ fail "Did not find exif header" - zeros <- getWord16be - unless (zeros == 0) $ fail "Expected zeros after exif header" + _app1DataSize <- lift getWord16be + exifHdr <- lift getWord32be + unless (exifHdr == 0x45786966) $ throwError "Did not find exif header" + zeros <- lift getWord16be + unless (zeros == 0) $ throwError "Expected zeros after exif header" -- beginning of tiff header -- we read whole thing to use -- in getting data from offsets: let tiffHeader = BL.drop 8 hdr - byteAlign <- getWord16be + byteAlign <- lift getWord16be let bigEndian = byteAlign == 0x4d4d let (getWord16, getWord32, getWord64) = if bigEndian @@ -213,17 +219,17 @@ exifHeader hdr = do num <- getWord32 den <- getWord32 return $ fromIntegral num / fromIntegral den - tagmark <- getWord16 - unless (tagmark == 0x002a) $ fail "Failed alignment sanity check" - ifdOffset <- getWord32 - skip (fromIntegral ifdOffset - 8) -- skip to IDF - numentries <- getWord16 - let ifdEntry = do - tag <- getWord16 >>= \t -> - maybe (return UnknownTagType) return - (M.lookup t tagTypeTable) - dataFormat <- getWord16 - numComponents <- getWord32 + tagmark <- lift getWord16 + unless (tagmark == 0x002a) $ throwError "Failed alignment sanity check" + ifdOffset <- lift getWord32 + lift $ skip (fromIntegral ifdOffset - 8) -- skip to IDF + numentries <- lift getWord16 + let ifdEntry :: ExceptT String Get (TagType, DataFormat) + ifdEntry = do + tag <- fromMaybe UnknownTagType . flip M.lookup tagTypeTable + <$> lift getWord16 + dataFormat <- lift getWord16 + numComponents <- lift getWord32 (fmt, bytesPerComponent) <- case dataFormat of 1 -> return (UnsignedByte . runGet getWord8, 1) @@ -238,9 +244,10 @@ exifHeader hdr = do 10 -> return (SignedRational . runGet getRational, 8) 11 -> return (SingleFloat . runGet getWord32 {- TODO -}, 4) 12 -> return (DoubleFloat . runGet getWord64 {- TODO -}, 8) - _ -> fail $ "Unknown data format " ++ show dataFormat + _ -> throwError $ "Unknown data format " ++ show dataFormat let totalBytes = fromIntegral $ numComponents * bytesPerComponent - payload <- if totalBytes <= 4 -- data is right here + payload <- lift $ + if totalBytes <= 4 -- data is right here then fmt <$> (getLazyByteString (fromIntegral totalBytes) <* skip (4 - totalBytes)) @@ -252,9 +259,9 @@ exifHeader hdr = do entries <- sequence $ replicate (fromIntegral numentries) ifdEntry subentries <- case lookup ExifOffset entries of Just (UnsignedLong offset) -> do - pos <- bytesRead - skip (fromIntegral offset - (fromIntegral pos - 8)) - numsubentries <- getWord16 + pos <- lift bytesRead + lift $ skip (fromIntegral offset - (fromIntegral pos - 8)) + numsubentries <- lift getWord16 sequence $ replicate (fromIntegral numsubentries) ifdEntry _ -> return [] |