runtime: if we don't handle a signal on a non-Go thread, raise it

In the past badsignal would crash the program.  In
https://golang.org/cl/10757044 badsignal was changed to call sigsend,
to fix issue #3250.  The effect of this was that when a non-Go thread
received a signal, and os/signal.Notify was not being used to check
for occurrences of the signal, the signal was ignored.

This changes the code so that if os/signal.Notify is not being used,
then the signal handler is reset to what it was, and the signal is
raised again.  This lets non-Go threads handle the signal as they
wish.  In particular, it means that a segmentation violation in a
non-Go thread will ordinarily crash the process, as it should.

Fixes #10139.
Update #11794.

Change-Id: I2109444aaada9d963ad03b1d071ec667760515e5
Reviewed-on: https://go-review.googlesource.com/12503
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/runtime/os3_solaris.go b/src/runtime/os3_solaris.go
index 53d7b96b0f..7caa72e3be 100644
--- a/src/runtime/os3_solaris.go
+++ b/src/runtime/os3_solaris.go
@@ -304,6 +304,12 @@ func updatesigmask(m sigmask) {
 	sigprocmask(_SIG_SETMASK, &mask, nil)
 }
 
+func unblocksig(sig int32) {
+	var mask sigset
+	mask.__sigbits[(sig-1)/32] |= 1 << ((uint32(sig) - 1) & 31)
+	sigprocmask(_SIG_UNBLOCK, &mask, nil)
+}
+
 //go:nosplit
 func semacreate() uintptr {
 	var sem *semt