You're right. ``tcsetattr'' doesn't affect the ``TOSTOP'' flag, but it
sends a SIGTTOU, when invoked from a background process. This, in
turn, causes the process to suspend unless SIGTTOU is blocked or
ignored!
SUSv2 says, this is the correct behaviour:
In local.glasgow-haskell-bugs, you wrote:
I guess it's another one of those dark corners that Volker seems to
wonder into with alarming regularity :)
Hey, you guys want real-world haskell applications, so you get them :)
Which reminds me of a yet untackled sigCHLD problem which shows up
only on
* Simon Marlow [EMAIL PROTECTED] [2001-01-16T02:17-0800]:
[...] The Solaris man page has this exact same paragraph,
although I can find no mention of this behaviour in the POSIX book I
have, the Linux man pages (surprise :-) or the Glibc docs.
Well, yes the man pages *ummh* sort of suck, but
In fact I can produce a simple example, either. So just the facts:
perftest@monster [11:46:35] ./Reader
[2] 86029
perftest@monster [11:46:40] jobs
[2]+ Stopped ./Reader
Sourcecode-snippet of Reader:
main = do
-- Posix.installHandler Posix.sigTTOU Posix.Ignore
But we're not changing any of the terminal flags, simply setting
the same ones again.
I'm totally stumped! Any ideas, anyone?
According to the manual page,
tcgetattr() ... This function may be invoked
from a background process; however, the terminal
* Michael Weber [EMAIL PROTECTED] [2001-01-16T00:00+0100]:
[...]
So, a solution seems to be, to block SIGTTOU during the call of
tcsetattr
[...]
BTW: Eventually, the following functions need the same shielding:
tcsetattr, tcsendbreak, tcflow, tcflush
Cheers,
M/
--
() ASCII ribbon
So it seems that there is possibly a feature/bug in the C library
such that calling tcsetattr() always suspends a backgrounded process,
regardless of the setting of TOSTOP. As yet, I haven't been able to
find a workaround. :-(
Yes, I went through a similar set of diagnoses myself after I
My local copy of ghc-4.08.1 likes to stop a program when running it
with "" (nohup) by default, I have to call
Posix.installHandler Posix.sigTTOU Posix.Ignore Nothing
first to get the desired behaviour. However, my local copy of
Stevens´ "UNIX Network Programming" says:
"SIGTTOU: [..]
Am 11. Jan 2001 um 11:54 MET schrieb Volker Stolz:
In fact I can produce a simple example, either. So just the facts:
*
Thats a "cant" of course. *sigh*
--
\usepackage[latin1]{inputenc}!
Volker Stolz * [EMAIL PROTECTED] * PGP + S/MIME
My local copy of ghc-4.08.1 likes to stop a program when running it
with "" (nohup) by default, I have to call
Posix.installHandler Posix.sigTTOU Posix.Ignore Nothing
first to get the desired behaviour. However, my local copy of
Stevens "UNIX Network Programming" says:
"SIGTTOU: [..] By
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