src/lib/libc/sys/rfork.2, branch releng/14.0

Remove $FreeBSD$: two-line nroff pattern

2023-08-16T17:55:10+00:00

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

posix_spawn(3): handle potential signal issues with vfork

2019-09-25T19:22:03+00:00

Described in [1], signal handlers running in a vfork child have
opportunities to corrupt the parent's state. Address this by adding a new
rfork(2) flag, RFSPAWN, that has vfork(2) semantics but also resets signal
handlers in the child during creation.

x86 uses rfork_thread(3) instead of a direct rfork(2) because rfork with
RFMEM/RFSPAWN cannot work when the return address is stored on the stack --
further information about this problem is described under RFMEM in the
rfork(2) man page.

Addressing this has been identified as a prerequisite to using posix_spawn
in subprocess on FreeBSD [2].

[1] https://ewontfix.com/7/
[2] https://bugs.python.org/issue35823

Reviewed by:	jilles, kib
Differential Revision:	https://reviews.freebsd.org/D19058

rfork(2): add RFSPAWN flag

2019-09-25T19:20:41+00:00

When RFSPAWN is passed, rfork exhibits vfork(2) semantics but also resets
signal handlers in the child during creation to avoid a point of corruption
of parent state from the child.

This flag will be used by posix_spawn(3) to handle potential signal issues.

Reviewed by:	jilles, kib
Differential Revision:	https://reviews.freebsd.org/D19058

Document RFTSIGZMB. Fix spelling of SIGCHLD. Note that signals are

2011-07-12T20:38:42+00:00

delivered, not returned.

MFC after:	1 week

rfork(2): Discourage rfork_thread-like approaches.

2011-03-15T23:51:47+00:00

Calling rfork_thread(3) does not interoperate with pthreads and global state
is not properly protected.

Remove the BUGS section suggesting LinuxThreads entirely. With the current
pthread library libthr, all threads are kernel-level entities so there seems
little reason to use LinuxThreads.

Document RFTHREAD

2007-05-14T13:58:54+00:00

PR:		docs/78915
Submitted by:	Marc Olzheim 
MFC after:	1 week

Expand *n't contractions.

2005-02-13T22:25:33+00:00

Sort sections.

2005-01-20T09:17:07+00:00

Mechanically kill hard sentence breaks.

2004-07-02T23:52:20+00:00

Correct the return value of vfork(2) and rfork(2) in their

2003-04-27T21:01:34+00:00

manual page function prototypes.