From a0b9248d78eba93d71c7973ccb1df4e8226f905e Mon Sep 17 00:00:00 2001
From: mb21 <mb21@users.noreply.github.com>
Date: Thu, 27 Dec 2018 17:11:10 +0100
Subject: [PATCH] Replace read with safeRead

closes #5180
---
 src/Text/Pandoc/Readers/TikiWiki.hs |  9 ++++++---
 src/Text/Pandoc/Writers/Docx.hs     | 10 +++++-----
 src/Text/Pandoc/Writers/LaTeX.hs    | 12 +++++++-----
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/src/Text/Pandoc/Readers/TikiWiki.hs b/src/Text/Pandoc/Readers/TikiWiki.hs
index 8458b05e5e8d..8e01a80f84f2 100644
--- a/src/Text/Pandoc/Readers/TikiWiki.hs
+++ b/src/Text/Pandoc/Readers/TikiWiki.hs
@@ -32,7 +32,7 @@ import Text.Pandoc.Definition
 import Text.Pandoc.Logging (Verbosity (..))
 import Text.Pandoc.Options
 import Text.Pandoc.Parsing hiding (enclosed, nested)
-import Text.Pandoc.Shared (crFilter)
+import Text.Pandoc.Shared (crFilter, safeRead)
 import Text.Pandoc.XML (fromEntities)
 import Text.Printf (printf)
 
@@ -500,9 +500,12 @@ emph = try $ fmap B.emph (enclosed (string "''") nestedInlines)
 escapedChar :: PandocMonad m => TikiWikiParser m B.Inlines
 escapedChar = try $ do
   string "~"
-  inner <- many1 $ oneOf "0123456789"
+  mNumber <- safeRead <$> many1 digit
   string "~"
-  return $B.str [toEnum (read inner :: Int) :: Char]
+  return $ B.str $
+    case mNumber of
+      Just number -> [toEnum (number :: Int) :: Char]
+      Nothing     -> []
 
 -- UNSUPPORTED, as there doesn't seem to be any facility in calibre
 -- for this
diff --git a/src/Text/Pandoc/Writers/Docx.hs b/src/Text/Pandoc/Writers/Docx.hs
index c2a160320b4b..4f642871a708 100644
--- a/src/Text/Pandoc/Writers/Docx.hs
+++ b/src/Text/Pandoc/Writers/Docx.hs
@@ -234,11 +234,11 @@ writeDocx opts doc@(Pandoc meta _) = do
 
   -- Get the available area (converting the size and the margins to int and
   -- doing the difference
-  let pgContentWidth = (-) <$> (read <$> mbAttrSzWidth ::Maybe Integer)
-                       <*> (
-                         (+) <$> (read <$> mbAttrMarRight ::Maybe Integer)
-                         <*> (read <$> mbAttrMarLeft ::Maybe Integer)
-                       )
+  let pgContentWidth = mbAttrSzWidth >>= safeRead
+                       >>= subtrct mbAttrMarRight
+                       >>= subtrct mbAttrMarLeft
+        where
+          subtrct mbStr = \x -> mbStr >>= safeRead >>= (\y -> Just $ x - y)
 
   -- styles
   mblang <- toLang $ getLang opts meta
diff --git a/src/Text/Pandoc/Writers/LaTeX.hs b/src/Text/Pandoc/Writers/LaTeX.hs
index ca8295f0a3db..f9bee886efd3 100644
--- a/src/Text/Pandoc/Writers/LaTeX.hs
+++ b/src/Text/Pandoc/Writers/LaTeX.hs
@@ -553,16 +553,18 @@ blockToLaTeX (Div (identifier,classes,kvs) bs)
                         else id
           wrapColumn  = if "column" `elem` classes
                         then \contents ->
-                               let fromPct xs =
-                                     case reverse xs of
-                                       '%':ds -> showFl (read (reverse ds) / 100 :: Double)
-                                       _      -> xs
-                                   w = maybe "0.48" fromPct (lookup "width" kvs)
+                               let w = maybe "0.48" fromPct (lookup "width" kvs)
                                in  inCmd "begin" "column" <>
                                    braces (text w <> "\\textwidth")
                                    $$ contents
                                    $$ inCmd "end" "column"
                         else id
+          fromPct xs =
+            case reverse xs of
+              '%':ds -> case safeRead (reverse ds) of
+                          Just digits -> showFl (digits / 100 :: Double)
+                          Nothing -> xs
+              _      -> xs
           wrapDir = case lookup "dir" kvs of
                       Just "rtl" -> align "RTL"
                       Just "ltr" -> align "LTR"