CVS commit: src/bin/sh

["Robert Elz" <kre%netbsd.org@localhost>]

Module Name:    src
Committed By:   kre
Date:           Mon May 18 16:40:00 UTC 2026

Modified Files:
        src/bin/sh: eval.c jobs.c jobs.h trap.c

Log Message:
PR bin/60275 discard even less arriving signals

Avoid signals arriving immediately after a fork() (or vfork())
by blocking everything (everything possible) while the fork()
happens, in the parent, for (close to) the minimum possible time,
in the child, until it has its state init'd enough that it is
safe for signals to arrive.

Further, if a signal does arrive (in a child) which was trapped
in the parent, but hasn't been cleaned up fully yet, instead of
simply ignoring it, send it to ourselves, after setting its state
to SIG_DFL (which is what would eventually happen to a trapped
signal anyway).   If that doesn't kill us, then we will end up
(harmlessly) setting the state to SIG_DFL again later as would happen
if the signal hadn't arrived in this short window; we cannot record that
it happened to avoid that, as we might be in a vforked child, and
anything recorded by that would be visible back in the parent later
(where the signal action was not changed).

Always use raise(N) rather than kill(getpid(), N) - just to save an
unnecessary getpid() sys call.  Of course, the current implementation
of raise() does much the same (just _lwp_self() rather than getpid())
but one can imagine a future where raise() was raised to the status of
being a sys call of its own (it would be a trivial one to implement).

After this change, the previous change to trap.c is probably no longer
needed (will never be invoked) as the situation which allowed a (parent)
trapped signal to be received in the child, without immediately being
ignored by onsig() should no longer be possible (the signal blocking
should prevent that).   However it is very small, correct if it were to
be invoked, and harmless otherwise.


To generate a diff of this commit:
cvs rdiff -u -r1.197 -r1.198 src/bin/sh/eval.c
cvs rdiff -u -r1.125 -r1.126 src/bin/sh/jobs.c
cvs rdiff -u -r1.27 -r1.28 src/bin/sh/jobs.h
cvs rdiff -u -r1.59 -r1.60 src/bin/sh/trap.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.