Environment variable does not work (especially DARCS_EDITOR)
ry102 at rz.uni-karlsruhe.de
Sat Apr 16 15:40:36 EDT 2005
[ crossposted to libraries at haskell.org ]
Tommy Pettersson <ptp at lysator.liu.se> writes:
> A likely source of the problem can be that pico aborts if its
> stdin or stdout isn't a tty. I have that problem with nvi.
> If you run darcs 1.0.2 you can try and set DARCS_EDITOR to
> "pico </dev/tty >/dev/tty". If you run a later build you
> may have to write a wrapper script like
> pico </dev/tty >/dev/tty
> since the to-be-next stable darcs not always perform the
> redirection on the system call any longer.
> Or, if this turns out to be the problem, and if you know how
> to make darcs do this redirection of stdin/out in a portable
> way, fix it in the darcs source.
The problem seems to be related to rawSystem and the ghc RTS (at
least GHC 6.4). GHC sets stdin/stdout/stderr to nonblocking mode
on startup and nvi doesn't like that. There is a comment in
ghc/rts/RtsUtils.c that resetNonBlockingFd is called before
exiting because leaving standard file descriptors in nonblocking
mode confuses some shells.
module Main where
main = rawSystem "nvi" 
The test program works after applying the following patch to GHC
that disables nonblocking mode after the fork and before the exec.
diff -u -r1.7 runProcess.c
--- libraries/base/cbits/runProcess.c 27 Mar 2005 13:41:19 -0000 1.7
+++ libraries/base/cbits/runProcess.c 16 Apr 2005 19:08:52 -0000
@@ -62,6 +62,10 @@
dfl.sa_handler = (void *)quithandler;
(void)sigaction(SIGQUIT, &dfl, NULL);
dup2 (fdStdInput, STDIN_FILENO);
dup2 (fdStdOutput, STDOUT_FILENO);
I'm not sure how to handle that in darcs without copying/reimplementing
the parts of System.Cmd we need.
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