Fix signal chain to allow for signal() call to be used

Bug: 17320614
Change-Id: Ia917307fb1b593644f524518e11e295b3c64be01

8 files changed, 167 insertions, 6 deletions

diff --git a/sigchainlib/sigchain.cc b/sigchainlib/sigchain.cc
index c655226..50bfe70 100644
--- a/sigchainlib/sigchain.cc
+++ b/sigchainlib/sigchain.cc
@@ -34,7 +34,7 @@ namespace art {
 
 class SignalAction {
  public:
-  SignalAction() : claimed_(false) {
+  SignalAction() : claimed_(false), uses_old_style_(false) {
   }
 
   // Claim the signal and keep the action specified.
@@ -60,13 +60,22 @@ class SignalAction {
   }
 
   // Change the recorded action to that specified.
-  void SetAction(const struct sigaction& action) {
+  // If oldstyle is true then this action is from an older style signal()
+  // call as opposed to sigaction().  In this case the sa_handler is
+  // used when invoking the user's handler.
+  void SetAction(const struct sigaction& action, bool oldstyle) {
     action_ = action;
+    uses_old_style_ = oldstyle;
+  }
+
+  bool OldStyle() const {
+    return uses_old_style_;
   }
 
  private:
   struct sigaction action_;     // Action to be performed.
   bool claimed_;                // Whether signal is claimed or not.
+  bool uses_old_style_;         // Action is created using signal().  Use sa_handler.
 };
 
 // User's signal handlers
@@ -115,7 +124,7 @@ void InvokeUserSignalHandler(int sig, siginfo_t* info, void* context) {
   }
 
   const struct sigaction& action = user_sigactions[sig].GetAction();
-  if ((action.sa_flags & SA_SIGINFO) == 0) {
+  if (user_sigactions[sig].OldStyle()) {
     if (action.sa_handler != NULL) {
       action.sa_handler(sig);
     } else {
@@ -145,7 +154,7 @@ int sigaction(int signal, const struct sigaction* new_action, struct sigaction*
       *old_action = user_sigactions[signal].GetAction();
     }
     if (new_action != NULL) {
-      user_sigactions[signal].SetAction(*new_action);
+      user_sigactions[signal].SetAction(*new_action, false);
     }
     return 0;
   }
@@ -168,6 +177,45 @@ int sigaction(int signal, const struct sigaction* new_action, struct sigaction*
   return linked_sigaction(signal, new_action, old_action);
 }
 
+sighandler_t signal(int signal, sighandler_t handler) {
+  struct sigaction sa;
+  sigemptyset(&sa.sa_mask);
+  sa.sa_handler = handler;
+  sa.sa_flags = SA_RESTART;
+  sighandler_t oldhandler;
+
+  // If this signal has been claimed as a signal chain, record the user's
+  // action but don't pass it on to the kernel.
+  // Note that we check that the signal number is in range here.  An out of range signal
+  // number should behave exactly as the libc sigaction.
+  if (signal > 0 && signal < _NSIG && user_sigactions[signal].IsClaimed()) {
+    oldhandler = reinterpret_cast<sighandler_t>(user_sigactions[signal].GetAction().sa_handler);
+    user_sigactions[signal].SetAction(sa, true);
+    return oldhandler;
+  }
+
+  // Will only get here if the signal chain has not been claimed.  We want
+  // to pass the sigaction on to the kernel via the real sigaction in libc.
+
+  void* linked_sigaction_sym = dlsym(RTLD_NEXT, "sigaction");
+  if (linked_sigaction_sym == nullptr) {
+    linked_sigaction_sym = dlsym(RTLD_DEFAULT, "sigaction");
+    if (linked_sigaction_sym == nullptr ||
+        linked_sigaction_sym == reinterpret_cast<void*>(sigaction)) {
+      log("Unable to find next sigaction in signal chain");
+      abort();
+    }
+  }
+
+  typedef int (*SigAction)(int, const struct sigaction*, struct sigaction*);
+  SigAction linked_sigaction = reinterpret_cast<SigAction>(linked_sigaction_sym);
+  if (linked_sigaction(signal, &sa, &sa) == -1) {
+    return SIG_ERR;
+  }
+
+  return reinterpret_cast<sighandler_t>(sa.sa_handler);
+}
+
 int sigprocmask(int how, const sigset_t* bionic_new_set, sigset_t* bionic_old_set) {
   const sigset_t* new_set_ptr = bionic_new_set;
   sigset_t tmpset;
diff --git a/test/004-SignalTest/signaltest.cc b/test/004-SignalTest/signaltest.cc
index f09fc26..a6d9b66 100644
--- a/test/004-SignalTest/signaltest.cc
+++ b/test/004-SignalTest/signaltest.cc
@@ -87,12 +87,12 @@ extern "C" JNIEXPORT void JNICALL Java_Main_terminateSignalTest(JNIEnv*, jclass)
 
 // Prevent the compiler being a smart-alec and optimizing out the assignment
 // to nullptr.
-char *p = nullptr;
+char *go_away_compiler = nullptr;
 
 extern "C" JNIEXPORT jint JNICALL Java_Main_testSignal(JNIEnv*, jclass) {
 #if defined(__arm__) || defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
   // On supported architectures we cause a real SEGV.
-  *p = 'a';
+  *go_away_compiler = 'a';
 #else
   // On other architectures we simulate SEGV.
   kill(getpid(), SIGSEGV);
diff --git a/test/004-SignalTest2/expected.txt b/test/004-SignalTest2/expected.txt
new file mode 100644
index 0000000..fd5ec00
--- /dev/null
+++ b/test/004-SignalTest2/expected.txt
@@ -0,0 +1,5 @@
+init signal test
+Caught NullPointerException
+Caught StackOverflowError
+signal caught
+Signal test OK
diff --git a/test/004-SignalTest2/info.txt b/test/004-SignalTest2/info.txt
new file mode 100644
index 0000000..00b0d9a
--- /dev/null
+++ b/test/004-SignalTest2/info.txt
@@ -0,0 +1 @@
+Imported from oat tests.
diff --git a/test/004-SignalTest2/signaltest.cc b/test/004-SignalTest2/signaltest.cc
new file mode 100644
index 0000000..47b1eb6
--- /dev/null
+++ b/test/004-SignalTest2/signaltest.cc
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "jni.h"
+
+#include <sys/ucontext.h>
+
+static int signal_count;
+static const int kMaxSignal = 2;
+
+static void signalhandler(int sig) {
+  printf("signal caught\n");
+  ++signal_count;
+  if (signal_count > kMaxSignal) {
+     printf("too many signals\n");
+     abort();
+  }
+  printf("Signal test OK\n");
+  exit(0);
+}
+
+sighandler_t oldsignal;
+
+extern "C" JNIEXPORT void JNICALL Java_Main_initSignalTest2(JNIEnv*, jclass) {
+  oldsignal = signal(SIGSEGV, reinterpret_cast<sighandler_t>(signalhandler));
+}
+
+// Prevent the compiler being a smart-alec and optimizing out the assignment
+// to nullptr.
+char *go_away_compiler2 = nullptr;
+
+extern "C" JNIEXPORT void JNICALL Java_Main_testSignal2(JNIEnv*, jclass) {
+  *go_away_compiler2 = 'a';
+}
+
diff --git a/test/004-SignalTest2/src/Main.java b/test/004-SignalTest2/src/Main.java
new file mode 100644
index 0000000..7799e8c
--- /dev/null
+++ b/test/004-SignalTest2/src/Main.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * 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.
+ */
+
+public class Main {
+    private static native void initSignalTest2();
+    private static native void testSignal2();
+
+    private static void stackOverflow() {
+       stackOverflow();
+    }
+
+    public static void main(String[] args) {
+        System.loadLibrary("arttest");
+
+        System.out.println("init signal test");
+        initSignalTest2();
+        try {
+            Object o = null;
+            int hash = o.hashCode();
+
+            // Should never get here.
+            System.out.println("hash: " + hash);
+            throw new AssertionError();
+        } catch (NullPointerException e) {
+            System.out.println("Caught NullPointerException");
+        }
+        try {
+            stackOverflow();
+
+            // Should never get here.
+            throw new AssertionError();
+        } catch (StackOverflowError e) {
+            System.out.println("Caught StackOverflowError");
+        }
+
+        // Test that a signal in native code works.
+        testSignal2();
+    }
+}
diff --git a/test/Android.libarttest.mk b/test/Android.libarttest.mk
index 2d139a6..1054203 100644
--- a/test/Android.libarttest.mk
+++ b/test/Android.libarttest.mk
@@ -21,6 +21,7 @@ include art/build/Android.common_build.mk
 LIBARTTEST_COMMON_SRC_FILES := \
   004-JniTest/jni_test.cc \
   004-SignalTest/signaltest.cc \
+  004-SignalTest2/signaltest.cc \
   004-ReferenceMap/stack_walk_refmap_jni.cc \
   004-StackWalk/stack_walk_jni.cc \
   004-UnsafeTest/unsafe_test.cc \
diff --git a/test/Android.run-test.mk b/test/Android.run-test.mk
index e4ee4a7..0b6b27a 100644
--- a/test/Android.run-test.mk
+++ b/test/Android.run-test.mk
@@ -189,6 +189,7 @@ TEST_ART_BROKEN_NO_PREBUILD_TESTS :=
 # Tests that are broken with tracing.
 TEST_ART_BROKEN_TRACE_RUN_TESTS := \
   004-SignalTest \
+  004-SignalTest2 \
   018-stack-overflow \
   097-duplicate-method \
   107-int-math2