On Oct 17, 2007, at 0:39 , Donn Cave wrote:
On Oct 16, 2007, at 7:31 PM, Brandon S. Allbery KF8NH wrote:
I could dig for official confirmation, but this is my
understanding of both POSIX and SUS, and portable C programs
generally #define FD_CLOEXEC to 1 if it doesn't already exist,
since the value *is* standard even though the name is not.
I find `runInteractiveProcess' in System.Process, in the
documentation -
not System.Posix.Process. Possibly the C macro is less important than
the cross-platform semantics relating to this problem. I.e., what
happens
on Microsoft Windows. I sure wouldn't know. Does a process even
inherit
pipe file descriptors?
The context of my message was a proposal for how to fix it on POSIX
systems. I do not claim to have sufficient understanding of Win32
APIs to fix that implementation --- but I suspect that there are
already many other implementation differences between the POSIX and
Win32 versions of System.Process, if only because popen(), fork(),
and exec() are entirely foreign concepts in Win32.
As for closing file descriptors explicitly - if I remember right
what I've seen
in the NetBSD source, the UNIX popen() implementation may years ago
have closed all file descriptors, but now it keeps track of the
ones it created,
and only closes them. I think that's the way to go, if closing fds.
Either implementation causes problems; security folks tend to prefer
that all file descriptors other than 0-2 (0-4 on Windows?) be closed,
and 0-2(4) be forced open (on /dev/null if they're not already
open). But in this case, the idea is to set FD_CLOEXEC on (and only
on) file descriptors opened by the Haskell runtime, so you would get
the same effect as tracking file descriptors manually.
--
brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED]
system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED]
electrical and computer engineering, carnegie mellon university KF8NH
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