X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FUnix.hs;h=f26263a42cca9de9c9894cdc465116d96c6da506;hb=HEAD;hp=a4389bee0e844ea7cd7024d608e3e126033bc926;hpb=ac3a81eb6d0f8ca4e212752d5b390a4fc220cceb;p=dead%2Fhtsn.git

diff --git a/src/Unix.hs b/src/Unix.hs
index a4389be..f26263a 100644
--- a/src/Unix.hs
+++ b/src/Unix.hs
@@ -5,13 +5,18 @@ where
 
 import Control.Concurrent ( ThreadId, myThreadId )
 import Control.Exception ( throwTo )
+import Control.Monad ( unless )
+import System.Directory ( createDirectory, doesDirectoryExist )
 import System.Exit ( ExitCode( ExitSuccess ) )
+import System.FilePath ( dropFileName, dropTrailingPathSeparator )
+import System.IO.Error ( catchIOError )
 import System.Posix (
   GroupEntry ( groupID ),
   GroupID,
   Handler ( Catch ),
   UserEntry ( userID ),
   UserID,
+  exitImmediately,
   getGroupEntryForName,
   getProcessID,
   getRealGroupID,
@@ -19,7 +24,9 @@ import System.Posix (
   getUserEntryForName,
   installHandler,
   removeLink,
+  setFileCreationMask,
   setGroupID,
+  setOwnerAndGroup,
   setUserID,
   sigTERM )
 import System.Posix.Daemonize ( daemonize )
@@ -28,7 +35,7 @@ import Configuration (
   Configuration( pidfile,
                  run_as_group,
                  run_as_user ))
-import Logging ( log_info )
+import Network.Services.TSN.Report ( report_error, report_info )
 
 -- | Retrieve the uid associated with the given system user name. We
 --   take a Maybe String as an argument so the user name can be passed
@@ -51,35 +58,93 @@ get_group_id (Just s) = fmap groupID (getGroupEntryForName s)
 -- | This function will be called in response to a SIGTERM; i.e. when
 --   someone tries to kill our process. We simply delete the PID file
 --   and signal our parent thread to quit (successfully).
+--
+--   If that doesn't work, report the error and quit rudely.
+--
 graceful_shutdown :: Configuration -> ThreadId -> IO ()
 graceful_shutdown cfg main_thread_id = do
-  log_info "SIGTERM received, removing PID file and shutting down."
-  removeLink (pidfile cfg)
-  throwTo main_thread_id ExitSuccess
+  report_info "SIGTERM received, removing PID file and shutting down."
+  catchIOError try_nicely (\e -> do
+                             report_error (show e)
+                             exitImmediately ExitSuccess )
+  where
+    try_nicely = do
+      removeLink (pidfile cfg)
+      throwTo main_thread_id ExitSuccess
 
 
+-- | Create the directory in which we intend to store the PID
+--   file. This will *not* create any parent directories. The PID
+--   directory will have its owner/group changed to the user/group
+--   under which we'll be running. No permissions will be set; the
+--   system's umask must allow owner-write.
+--
+--   This is intended to create one level beneath either /var/run or
+--   /run which often do not survive a reboot.
+--
+--   If the directory already exists, it is left alone; that is, we
+--   don't change its owner/group.
+--
+create_pid_directory :: FilePath -- ^ The directory to contain the PID file.
+                     -> UserID   -- ^ Owner of the new directory if created.
+                     -> GroupID  -- ^ Group of the new directory if created.
+                     -> IO ()
+create_pid_directory pid_directory uid gid = do
+  it_exists <- doesDirectoryExist pid_directory
+  unless it_exists $ do
+    report_info $ "Creating PID directory " ++ pid_directory ++ "."
+    createDirectory pid_directory
+    report_info $ "Changing owner/group of " ++ pid_directory ++
+                    " to " ++ (show uid) ++ "/" ++ (show gid) ++ "."
+    setOwnerAndGroup pid_directory uid gid
+
 -- | Write a PID file, install a SIGTERM handler, drop privileges, and
 --   finally do the daemonization dance.
 --
 full_daemonize :: Configuration -> IO () -> IO ()
-full_daemonize cfg program =
+full_daemonize cfg program = do
+  uid <- get_user_id (run_as_user cfg)
+  gid <- get_group_id (run_as_group cfg)
+
+  -- This will have to be done as root and the result chowned to our
+  -- user/group, so it must happen before daemonizing.
+  let pid_directory = dropTrailingPathSeparator $ dropFileName $ pidfile cfg
+  create_pid_directory pid_directory uid gid
+
+  -- The call to 'daemonize' will set the umask to zero, but we want
+  -- to retain it. So, we set the umask to zero before 'daemonize'
+  -- can, so that we can record the previous umask value (returned by
+  -- setFileCreationMask).
+  orig_umask <- setFileCreationMask 0
+
   -- This is the 'daemonize' from System.Posix.Daemonize.
-  daemonize program'
+  daemonize (program' orig_umask uid gid)
   where
     -- We need to do all this stuff *after* we daemonize.
-    program' = do
-      -- First write the PID file which probably requires root.
-      pid <- getProcessID
-      writeFile (pidfile cfg) (show pid)
-
-      -- We need to pass the thread ID to the signal handler so it
-      -- knows which process to "exit."
+    program' orig_umask uid gid = do
+      -- First we install a signal handler for sigTERM. We need to
+      -- pass the thread ID to the signal handler so it knows which
+      -- process to "exit."
       tid <- myThreadId
       _ <- installHandler sigTERM (Catch (graceful_shutdown cfg tid)) Nothing
 
-      -- Then drop privileges.
-      get_user_id  (run_as_user cfg)  >>= setUserID
-      get_group_id (run_as_group cfg) >>= setGroupID
+      -- Next we drop privileges. Group ID has to go first, otherwise
+      -- you ain't root to change groups.
+      setGroupID gid
+      setUserID uid
+
+      -- Now we create the PID file.
+      pid <- getProcessID
+
+      -- The PID file needs to be read-only for anyone but its
+      -- owner. Hopefully the umask accomplishes this!
+      _ <- setFileCreationMask orig_umask
+
+      -- When we later attempt to delete the PID file, it requires
+      -- write permission to the parent directory and not to the PID
+      -- file itself. Therefore, if that's going to work, this has to
+      -- work, even as a limited user.
+      writeFile (pidfile cfg) (show pid)
 
       -- Finally run the program we were asked to.
       program