#9143: feature request: way to set actual program argv -------------------------------------+------------------------------------- Reporter: joeyhess | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.8.2 Component: Runtime | Keywords: System | Architecture: Unknown/Multiple Resolution: | Difficulty: Moderate (less Operating System: Linux | than a day) Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * owner: simonmar => * status: closed => new * resolution: wontfix => Comment: Or maybe that stackoverflow answer is not out of date, but it's just only one half of the story? I added this comment: "This seems to only change the name in the output of 'ps -A', 'ps -a' 'ps -d', 'ps -e' and maybe others, whereas 'ps a', 'ps -ef', 'ps f' and probably others still show the original command line arguments." Changing argv[0] would then be the other half of the story, like you suggested in the description. This C example shows "othername" when using 'ps -ef', but not when doing 'ps -e'. In `top` you can toggle between the two by hitting the `c` key. {{{ #include #include int main(int argc, char** argv) { strcpy(argv[0],"othername"); sleep(1000); return 0; } }}} So doing both would be needed: change `argv` and call `prctl`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9143#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#9143: feature request: way to set actual program argv -------------------------------------+------------------------------------- Reporter: joeyhess | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.8.2 Resolution: | Keywords: Operating System: Linux | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Description changed by bgamari: Old description:

It's not currently possible to write a program with ghc that changes its argv, so as to change what the program name/parameters appear to be in ps.

An example of a program that does this is sshd, which arranges for the process name to say which user it's serving. For example, "sshd: joey [priv]"

I'd like to be able to write such programs using haskell too. Also, I have a haskell program that, due to the way it is executed, has a really horrible display in ps:

/usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/lib64/ld-linux-x86-64.so.2 --library-path /usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/lib/x86_64-linux- gnu:/usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/usr/lib/x86_64-linux- gnu:/usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/lib64:/usr/local/propellor/docker /android-git-annex- builder.orca.kitenet.net.propellor.shim/etc/ld.so.conf.d:/usr/local/propellor/docker /android-git-annex-builder.orca.kitenet.net.propellor.shim/usr/lib/x86_64 -linux-gnu/audit:/usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/usr/lib/x86_64-linux-gnu/gconv /usr/local/propellor/propellor

That's enough motivation for me to dig into this. :)

In rts/RtsMain.c, progargv is set to point to argv. However, it's static, so this cannot be (ab)used from the FFI to change argv.

So, a minimal change would be to make progargv not be static, and perhaps give it a more formal name or minimal FFI binding. A GHC-specific library could then use this to modify argv.

The haskell interface I'm considering would be:

displayArgv :: [String] -> IO ()

It would need to truncate strings to fit within the available argv space.

(This would not affect the argv used by System.Environment, which is a copy of argv.)

New description: It's not currently possible to write a program with ghc that changes its argv, so as to change what the program name/parameters appear to be in ps. An example of a program that does this is sshd, which arranges for the process name to say which user it's serving. For example, "sshd: joey [priv]" I'd like to be able to write such programs using haskell too. Also, I have a haskell program that, due to the way it is executed, has a really horrible display in ps: {{{ /usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/lib64/ld-linux-x86-64.so.2 --library-path /usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/lib/x86_64-linux- gnu:/usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/usr/lib/x86_64-linux- gnu:/usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/lib64:/usr/local/propellor/docker /android-git-annex- builder.orca.kitenet.net.propellor.shim/etc/ld.so.conf.d:/usr/local/propellor/docker /android-git-annex-builder.orca.kitenet.net.propellor.shim/usr/lib/x86_64 -linux-gnu/audit:/usr/local/propellor/docker/android-git-annex- builder.orca.kitenet.net.propellor.shim/usr/lib/x86_64-linux-gnu/gconv /usr/local/propellor/propellor }}} That's enough motivation for me to dig into this. :) In rts/RtsMain.c, progargv is set to point to argv. However, it's static, so this cannot be (ab)used from the FFI to change argv. So, a minimal change would be to make progargv not be static, and perhaps give it a more formal name or minimal FFI binding. A GHC-specific library could then use this to modify argv. The haskell interface I'm considering would be: {{{ displayArgv :: [String] -> IO () }}} It would need to truncate strings to fit within the available argv space. (This would not affect the argv used by `System.Environment`, which is a copy of argv.) -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9143#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#9143: feature request: way to set actual program argv -------------------------------------+------------------------------------- Reporter: joeyhess | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.8.2 Resolution: | Keywords: Operating System: Linux | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by pgj): As far as I know, on FreeBSD, the recommended method for changing the value of `argv[0]` is calling the [https://www.freebsd.org/cgi/man.cgi?query=setproctitle&sektion=3 setproctitle(3)] function. I am not sure if rest of `argv` could be changed safely. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9143#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler