033e4b086fMade all uses of openFd and dup set the close-on-exec flag, with a few exceptions when starting a git-annex daemon. Made openFdWithMode be used everywhere, rather than openFd. Adding a new parameter to it ensures I checked everything. And will help to make sure this gets considered in the future when opening fds. In lockPidFile, the only thing that keeps the pid file locked, once daemonize re-runs the command in a new session, is that the fd is inherited. In Utility.LogFile.redir, the new fd it dups to does not have the close-on-exec flag set, because this is used to set up the stdout and stderr fds, which need to be inherited by child processes. Same in Assistant.startDaemon where the browser gets started with the original stdout and stderr. This does nothing about uses of openFile and similar! Sponsored-By: mycroft
38 lines
1 KiB
Haskell
38 lines
1 KiB
Haskell
{- Opening files
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-
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- Copyright 2024 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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{-# LANGUAGE CPP #-}
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module Utility.OpenFile where
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#ifndef mingw32_HOST_OS
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import System.IO
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import System.Posix.IO
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import GHC.IO.FD
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import GHC.IO.Handle.FD
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import GHC.IO.Device
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import Utility.OpenFd
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import Utility.RawFilePath
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import Utility.FileSystemEncoding
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{- Usually, opening a Handle to a file that another thread also has open
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- for write is prevented, which avoids a lot of concurrency bugs especially
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- with lazy IO.
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-
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- However, sometimes one thread is writing and another thread really wants
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- to read from the same file. This bypasses the usual locking, by claiming
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- that an opened FD is a Stream.
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-}
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openFileBeingWritten :: RawFilePath -> IO Handle
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openFileBeingWritten f = do
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fd <- openFdWithMode f ReadOnly Nothing defaultFileFlags (CloseOnExecFlag True)
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(fd', fdtype) <- mkFD (fromIntegral fd) ReadMode (Just (Stream, 0, 0)) False False
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mkHandleFromFD fd' fdtype (fromRawFilePath f) ReadMode False Nothing
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#endif
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