start using kvm library from bsd for receiving swapinfo

Using this library allows us to receive swap info which is more
similar with result of command swapinfo.

3 files changed, 103 insertions, 41 deletions

diff --git a/src/Xmobar/Plugins/Monitors/Swap/FreeBSD.hs b/src/Xmobar/Plugins/Monitors/Swap/FreeBSD.hs
deleted file mode 100644
index 0e0c03d..0000000
--- a/src/Xmobar/Plugins/Monitors/Swap/FreeBSD.hs
+++ /dev/null
@@ -1,41 +0,0 @@
------------------------------------------------------------------------------
--- |
--- Module      :  Plugins.Monitors.Swap.FreeBSD
--- Copyright   :  (c) Andrea Rossato
--- License     :  BSD-style (see LICENSE)
---
--- Maintainer  :  Jose A. Ortega Ruiz <jao@gnu.org>
--- Stability   :  unstable
--- Portability :  unportable
---
--- A  swap usage monitor for Xmobar
---
------------------------------------------------------------------------------
-
-module Xmobar.Plugins.Monitors.Swap.FreeBSD (parseMEM) where
-
-import System.BSD.Sysctl (sysctlReadUInt, sysctlReadULong)
-
-isEnabled :: IO Bool
-isEnabled = do
-  enabled <- sysctlReadUInt "vm.swap_enabled"
-  return $ enabled == 1
-
-parseMEM' :: Bool -> IO [Float]
-parseMEM' False = return []
-parseMEM' True = do
-  swapIn <- sysctlReadUInt "vm.stats.vm.v_swapin"
-  swapTotal <- sysctlReadULong "vm.swap_total"
-  let tot = toInteger swapTotal
-      free = tot - toInteger swapIn
-
-  return $ res (fromInteger tot) (fromInteger free)
-  where
-    res :: Float -> Float -> [Float]
-    res _ 0 = []
-    res tot free = [(tot - free) / tot, tot, tot - free, free]
-
-parseMEM :: IO [Float]
-parseMEM = do
-  enabled <- isEnabled
-  parseMEM' enabled
diff --git a/src/Xmobar/Plugins/Monitors/Swap/FreeBSD.hsc b/src/Xmobar/Plugins/Monitors/Swap/FreeBSD.hsc
new file mode 100644
index 0000000..9c74e36
--- /dev/null
+++ b/src/Xmobar/Plugins/Monitors/Swap/FreeBSD.hsc
@@ -0,0 +1,102 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Plugins.Monitors.Swap.FreeBSD
+-- Copyright   :  (c) Andrea Rossato
+-- License     :  BSD-style (see LICENSE)
+--
+-- Maintainer  :  Jose A. Ortega Ruiz <jao@gnu.org>
+-- Stability   :  unstable
+-- Portability :  unportable
+--
+-- A  swap usage monitor for Xmobar
+--
+-----------------------------------------------------------------------------
+
+module Xmobar.Plugins.Monitors.Swap.FreeBSD (parseMEM) where
+
+import System.BSD.Sysctl (sysctlReadUInt)
+import Foreign
+import Foreign.C.Types
+import Foreign.C.String
+
+
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <kvm.h>
+#include <limits.h>
+#include <paths.h>
+#include <stdlib.h>
+
+
+foreign import ccall unsafe "kvm.h kvm_open" c_kvm_open :: CString -> CString -> CString -> CInt -> CString ->  IO (Ptr KVM_T)
+foreign import ccall "&kvm_close" c_kvm_close :: FinalizerPtr KVM_T
+foreign import ccall unsafe "kvm.h kvm_getswapinfo" c_kvm_getswapinfo :: Ptr KVM_T -> Ptr KVM_SWAP -> CInt -> CInt -> IO CInt
+
+data KVM_T
+data KvmT = KvmT !(ForeignPtr KVM_T)
+  deriving (Eq, Ord, Show)
+
+data KVM_SWAP
+data KvmSwap = KvmSwap !(ForeignPtr KVM_SWAP)
+  deriving (Eq, Ord, Show)
+
+getKvmT:: IO KvmT
+getKvmT = do
+  withCString "/dev/null" $ \dir -> do
+    kvm_t_ptr <- c_kvm_open nullPtr dir nullPtr #{const O_RDONLY} nullPtr
+    ptr <- newForeignPtr c_kvm_close kvm_t_ptr
+    return $ KvmT ptr
+
+getSwapData :: KvmT -> IO SwapData
+getSwapData (KvmT kvm_t_fp) = do
+  withForeignPtr kvm_t_fp $ \kvm_t_ptr -> do
+    allocaBytes #{size struct kvm_swap} $ \swap_ptr -> do
+      c_kvm_getswapinfo kvm_t_ptr swap_ptr 1 0
+      peek $ castPtr swap_ptr :: IO SwapData
+
+data SwapData = AvailableSwapData {
+  used :: Integer
+  , total :: Integer
+  } | NotAvailableSwapData
+  deriving (Show, Read, Eq)
+
+instance Storable SwapData where
+  alignment _ = #{alignment struct kvm_swap}
+  sizeOf _    = #{size struct kvm_swap}
+  peek ptr    = do
+    cused <- #{peek struct kvm_swap, ksw_used} ptr :: IO CUInt
+    ctotal <- #{peek struct kvm_swap, ksw_total} ptr :: IO CUInt
+    return $ AvailableSwapData {used = toInteger cused, total = toInteger ctotal}
+
+  poke _ _    = pure ()
+
+
+isEnabled :: IO Bool
+isEnabled = do
+  enabled <- sysctlReadUInt "vm.swap_enabled"
+  return $ enabled == 1
+
+parseMEM' :: Bool -> IO [Float]
+parseMEM' False = return []
+parseMEM' True = do
+  kvm_t <- getKvmT
+  swap <- getSwapData kvm_t
+  pagesize <- toInteger <$> sysctlReadUInt "vm.stats.vm.v_page_size"
+
+  let
+    swapTotal = total swap
+    swapUsed = used swap
+    tot = swapTotal * pagesize
+    fr = tot - swapUsed * pagesize
+
+  return $ res (fromInteger tot) (fromInteger fr)
+  where
+    res :: Float -> Float -> [Float]
+    res _ 0 = []
+    res t f = [(t-f)/t, t, t - f, f]
+
+parseMEM :: IO [Float]
+parseMEM = do
+  enabled <- isEnabled
+  parseMEM' enabled
diff --git a/xmobar.cabal b/xmobar.cabal
index 721e849..bcb70f9 100644
--- a/xmobar.cabal
+++ b/xmobar.cabal
@@ -296,6 +296,7 @@ library
     if os(freebsd)
        -- enables freebsd specific code
        extra-libraries: procstat
+                      , kvm
        build-depends: bsd-sysctl
        other-modules: Xmobar.Plugins.Monitors.Batt.FreeBSD,
                       Xmobar.Plugins.Monitors.Cpu.FreeBSD,