#7229: Detecting if a process was killed by a signal is impossible
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Reporter: benmachine | Owner:
Type: bug | Status: new
Priority: high | Milestone: 7.6.2
Component: libraries/process | Version:
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: None/Unknown
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by simonmar):
Ok, points taken. 128+signal is not good, because that overlaps with exit
codes.
Unfortunately we can't add the right information to `ExitCode`, because it
is a platform-independent type. The correct type already exists: it is
called `System.Posix.ProcessStatus`.
{{{
data ProcessStatus = Exited ExitCode
| Terminated Signal
| Stopped Signal
deriving (Eq, Ord, Show)
}}}
Unfortunately whoever wrote this forgot to add a `Bool` to indicate a core
dump in the `Terminated` constructor. We *could* fix that.
Now, the right thing to do would be to create a new `process-unix` package
containing
{{{
module System.Process.Posix where
waitForProcess :: ProcessHandle -> IO ProcessStatus
getProcessStatus :: ProcessHandle -> IO (Maybe ProcessStatus)
}}}
It can't be part of the `process` package because the API of a package
cannot differ depending on the platform. It could be part of the `unix`
package, but then we have to move a chunk of code from the `process`
package into the `unix` package, which is annoying.
I propose as an intermediate solution that we just fix the `ExitCode`
encoding: instead of 128+signal, use `(signal << 8) + exit code`, with a
core dump setting the `0x8000` bit.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7229#comment:6>
GHC <http://www.haskell.org/ghc/>
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