File remove-state-file-after-startup.patch of Package xmonad

From 89a8cc88c31163dd35d3182bbba7cdd0630ff54b Mon Sep 17 00:00:00 2001
From: Peter Jones <pjones@devalot.com>
Date: Thu, 30 Mar 2017 13:42:16 -0700
Subject: [PATCH] Remove the xmonad state file after reading it

Tries to make sure IO is not lazy so the file is processed before it
is removed from the file system.

Fixes #86 and friends.
---
 CHANGES.md               | 14 ++++++++++++++
 src/XMonad/Operations.hs | 16 +++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index fed3bc9..ebb104f 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,19 @@
 # Change Log / Release Notes
 
+## 0.14 (Not Yet Released)
+
+### Bug Fixes
+
+  * The state file that xmonad uses while restarting itself is now
+    removed after it is processed.  This fixes a bug that manifested
+    in several different ways:
+
+    - Names of old workspaces would be resurrected after a restart
+    - Screen sizes would be wrong after changing monitor configuration (#90)
+    - `spawnOnce` stopped working (xmonad/xmonad-contrib#155)
+    - Focus did not follow when moving between workspaces (#87)
+    - etc.
+
 ## 0.13 (February 10, 2017)
 
 ### Breaking Changes
diff --git a/src/XMonad/Operations.hs b/src/XMonad/Operations.hs
index 4b46571..7dbb45c 100644
--- a/src/XMonad/Operations.hs
+++ b/src/XMonad/Operations.hs
@@ -465,14 +465,21 @@ writeStateToFile = do
     catchIO (writeFile path $ show stateData)
 
 -- | Read the state of a previous xmonad instance from a file and
--- return that state.
+-- return that state.  The state file is removed after reading it.
 readStateFile :: (LayoutClass l Window, Read (l Window)) => XConfig l -> X (Maybe XState)
 readStateFile xmc = do
     path <- stateFileName
-    raw  <- userCode $ io (readFile path)
+
+    -- I'm trying really hard here to make sure we read the entire
+    -- contents of the file before it is removed from the file system.
+    sf' <- userCode . io $ do
+        raw <- withFile path ReadMode readStrict
+        return $! maybeRead reads raw
+
+    io (removeFile path)
 
     return $ do
-      sf <- maybeRead reads =<< raw
+      sf <- join sf'
 
       let winset = W.ensureTags layout (workspaces xmc) $ W.mapLayout (fromMaybe layout . maybeRead lreads) (sfWins sf)
           extState = M.fromList . map (second Left) $ sfExt sf
@@ -491,6 +498,9 @@ readStateFile xmc = do
                            [(x, "")] -> Just x
                            _         -> Nothing
 
+    readStrict :: Handle -> IO String
+    readStrict h = hGetContents h >>= \s -> length s `seq` return s
+
 -- | Migrate state from a previously running xmonad instance that used
 -- the older @--resume@ technique.
 {-# DEPRECATED migrateState "will be removed some point in the future." #-}