runtime: don't always block all signals on OpenBSD

Implement the changes from CL 10173 on OpenBSD.

Change-Id: I2db1cd8141fd392a34753a1b8113e2e0401173b9
Reviewed-on: https://go-review.googlesource.com/10342
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/runtime/os1_openbsd.go b/src/runtime/os1_openbsd.go
index 98af545f7fbed294d07727c9a4389c3fe92a2498..5ccf64246869a9a7d718daa8ad4853324b84c65b 100644 (file)
--- a/src/runtime/os1_openbsd.go
+++ b/src/runtime/os1_openbsd.go
@@ -149,6 +149,11 @@ func mpreinit(mp *m) {
 }
 
 func msigsave(mp *m) {
+       smask := (*uint32)(unsafe.Pointer(&mp.sigmask))
+       if unsafe.Sizeof(*smask) > unsafe.Sizeof(mp.sigmask) {
+               throw("insufficient storage for signal mask")
+       }
+       *smask = sigprocmask(_SIG_BLOCK, 0)
 }
 
 // Called to initialize a new m (including the bootstrap m).
@@ -161,11 +166,22 @@ func minit() {
 
        // Initialize signal handling
        signalstack((*byte)(unsafe.Pointer(_g_.m.gsignal.stack.lo)), 32*1024)
-       sigprocmask(_SIG_SETMASK, sigset_none)
+
+       // restore signal mask from m.sigmask and unblock essential signals
+       nmask := *(*uint32)(unsafe.Pointer(&_g_.m.sigmask))
+       for i := range sigtable {
+               if sigtable[i].flags&_SigUnblock != 0 {
+                       nmask &^= 1 << (uint32(i) - 1)
+               }
+       }
+       sigprocmask(_SIG_SETMASK, nmask)
 }
 
 // Called from dropm to undo the effect of an minit.
 func unminit() {
+       _g_ := getg()
+       smask := *(*uint32)(unsafe.Pointer(&_g_.m.sigmask))
+       sigprocmask(_SIG_SETMASK, smask)
        signalstack(nil, 0)
 }