Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 79 insertions, 0 deletions

diff --git a/pkg/sentry/kernel/signal_handlers.go b/pkg/sentry/kernel/signal_handlers.go
new file mode 100644
index 000000000..21ba4ee70
--- /dev/null
+++ b/pkg/sentry/kernel/signal_handlers.go
@@ -0,0 +1,79 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kernel
+
+import (
+	"sync"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
+)
+
+// SignalHandlers holds information about signal actions.
+type SignalHandlers struct {
+	// mu protects actions, as well as the signal state of all tasks and thread
+	// groups using this SignalHandlers object. (See comment on
+	// ThreadGroup.signalHandlers.)
+	mu sync.Mutex `state:"nosave"`
+
+	// actions is the action to be taken upon receiving each signal.
+	actions map[linux.Signal]arch.SignalAct
+}
+
+// NewSignalHandlers returns a new SignalHandlers specifying all default
+// actions.
+func NewSignalHandlers() *SignalHandlers {
+	return &SignalHandlers{
+		actions: make(map[linux.Signal]arch.SignalAct),
+	}
+}
+
+// Fork returns a copy of sh for a new thread group.
+func (sh *SignalHandlers) Fork() *SignalHandlers {
+	sh2 := NewSignalHandlers()
+	sh.mu.Lock()
+	defer sh.mu.Unlock()
+	for sig, act := range sh.actions {
+		sh2.actions[sig] = act
+	}
+	return sh2
+}
+
+// CopyForExec returns a copy of sh for a thread group that is undergoing an
+// execve. (See comments in Task.finishExec.)
+func (sh *SignalHandlers) CopyForExec() *SignalHandlers {
+	sh2 := NewSignalHandlers()
+	sh.mu.Lock()
+	defer sh.mu.Unlock()
+	for sig, act := range sh.actions {
+		if act.Handler == arch.SignalActIgnore {
+			sh2.actions[sig] = arch.SignalAct{
+				Handler: arch.SignalActIgnore,
+			}
+		}
+	}
+	return sh2
+}
+
+// dequeueActionLocked returns the SignalAct that should be used to handle sig.
+//
+// Preconditions: sh.mu must be locked.
+func (sh *SignalHandlers) dequeueAction(sig linux.Signal) arch.SignalAct {
+	act := sh.actions[sig]
+	if act.IsResetHandler() {
+		delete(sh.actions, sig)
+	}
+	return act
+}