1 files changed, 113 insertions, 0 deletions
diff --git a/init/reboot_utils.cpp b/init/reboot_utils.cpp
new file mode 100644
index 000000000..961030409
--- /dev/null
+++ b/init/reboot_utils.cpp
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2018 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 <sys/capability.h>
+#include <sys/reboot.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include <android-base/logging.h>
+#include <cutils/android_reboot.h>
+
+#include "capabilities.h"
+
+namespace android {
+namespace init {
+
+bool IsRebootCapable() {
+    if (!CAP_IS_SUPPORTED(CAP_SYS_BOOT)) {
+        PLOG(WARNING) << "CAP_SYS_BOOT is not supported";
+        return true;
+    }
+
+    ScopedCaps caps(cap_get_proc());
+    if (!caps) {
+        PLOG(WARNING) << "cap_get_proc() failed";
+        return true;
+    }
+
+    cap_flag_value_t value = CAP_SET;
+    if (cap_get_flag(caps.get(), CAP_SYS_BOOT, CAP_EFFECTIVE, &value) != 0) {
+        PLOG(WARNING) << "cap_get_flag(CAP_SYS_BOOT, EFFECTIVE) failed";
+        return true;
+    }
+    return value == CAP_SET;
+}
+
+void __attribute__((noreturn)) RebootSystem(unsigned int cmd, const std::string& rebootTarget) {
+    LOG(INFO) << "Reboot ending, jumping to kernel";
+
+    if (!IsRebootCapable()) {
+        // On systems where init does not have the capability of rebooting the
+        // device, just exit cleanly.
+        exit(0);
+    }
+
+    switch (cmd) {
+        case ANDROID_RB_POWEROFF:
+            reboot(RB_POWER_OFF);
+            break;
+
+        case ANDROID_RB_RESTART2:
+            syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
+                    LINUX_REBOOT_CMD_RESTART2, rebootTarget.c_str());
+            break;
+
+        case ANDROID_RB_THERMOFF:
+            reboot(RB_POWER_OFF);
+            break;
+    }
+    // In normal case, reboot should not return.
+    PLOG(ERROR) << "reboot call returned";
+    abort();
+}
+
+void InstallRebootSignalHandlers() {
+    // Instead of panic'ing the kernel as is the default behavior when init crashes,
+    // we prefer to reboot to bootloader on development builds, as this will prevent
+    // boot looping bad configurations and allow both developers and test farms to easily
+    // recover.
+    struct sigaction action;
+    memset(&action, 0, sizeof(action));
+    sigfillset(&action.sa_mask);
+    action.sa_handler = [](int signal) {
+        // These signal handlers are also caught for processes forked from init, however we do not
+        // want them to trigger reboot, so we directly call _exit() for children processes here.
+        if (getpid() != 1) {
+            _exit(signal);
+        }
+
+        // Calling DoReboot() or LOG(FATAL) is not a good option as this is a signal handler.
+        // RebootSystem uses syscall() which isn't actually async-signal-safe, but our only option
+        // and probably good enough given this is already an error case and only enabled for
+        // development builds.
+        RebootSystem(ANDROID_RB_RESTART2, "bootloader");
+    };
+    action.sa_flags = SA_RESTART;
+    sigaction(SIGABRT, &action, nullptr);
+    sigaction(SIGBUS, &action, nullptr);
+    sigaction(SIGFPE, &action, nullptr);
+    sigaction(SIGILL, &action, nullptr);
+    sigaction(SIGSEGV, &action, nullptr);
+#if defined(SIGSTKFLT)
+    sigaction(SIGSTKFLT, &action, nullptr);
+#endif
+    sigaction(SIGSYS, &action, nullptr);
+    sigaction(SIGTRAP, &action, nullptr);
+}
+
+}  // namespace init
+}  // namespace android