Subject: Re: signal(SIGSEGV, SIG_IGN) -> 100% CPU
To: None <email@example.com>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
Date: 06/10/1999 16:07:42
[Replying to two messages at once here.]
>> I looked at [making pipe() return EFAULT instead of SEGVing], and it
>> looks pretty simple.
> Of course, since pipe() is implemented in-kernel by socketpair(),
Not in the source tree I looked at ($NetBSD: uipc_syscalls.c,v 1.41);
sys_pipe() more or less mimics sys_socketpair(), but the two do not
actually share any common "create a connected pair of sockets" code.
Interestingly, socketpair() *does* return the file descriptors via
copyout(), unlike pipe().
> we could just call the latter from user space directly ....
I once thought that's how pipe() was done now (ie, it was really
pipe(3) rather than pipe(2)). But syscall traces and code reading
dispelled that illusion quickly. :-)
>> The only benefits I can see to changing this are (1) uniformity with
>> other syscalls, and the (current) manpage, wrt invalid pointer
>> arguments (EFAULT instead of a signal), and (2) removing a
>> special-case syscall from libc.
> My further argument was that the manual page wasn't even incorrect.
I agree with this last-quoted message (from cgd); with the wording
change it suggests ("will fail if" -> "can fail if", more or less), the
manpage becomes a complete non-issue. Nevertheless, uniformity of
semantics with other syscalls (especially socketpair(), it seems to me)
and uniformity of implementation with almost all other syscalls strike
me as reasons enough to do the change.
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