Add vport_trigger tool.
This tool reads any /sys/class/virtio-ports/vportXpY/name files and sets
up mirror properties in the format sys.cf.ser.<name> to specify the path
to device node like /dev/vportXpY.
The properties can be used as triggers to create symlinks to the desired
files and start the affected services. If the device nodes are already
the same name as the sysfs 'name' files, this tool has no effect.
This replaces a workaround in the kernel that renamed the virtio_serial
devices to the contents of the sysfs 'name' file, which is not an
upstreamable change.
Bug: 77656836
Change-Id: I0d32027315c5d9becd8f02f7c5a680108d03f036
diff --git a/guest/commands/vport_trigger/Android.mk b/guest/commands/vport_trigger/Android.mk
new file mode 100644
index 0000000..e994ce9
--- /dev/null
+++ b/guest/commands/vport_trigger/Android.mk
@@ -0,0 +1,26 @@
+# 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.
+
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := vport_trigger
+LOCAL_MODULE_TAGS := optional
+LOCAL_SRC_FILES := main.cpp
+LOCAL_SHARED_LIBRARIES := libcutils
+LOCAL_MULTILIB := first
+LOCAL_VENDOR_MODULE := true
+
+include $(BUILD_EXECUTABLE)
diff --git a/guest/commands/vport_trigger/main.cpp b/guest/commands/vport_trigger/main.cpp
new file mode 100644
index 0000000..d3f4710
--- /dev/null
+++ b/guest/commands/vport_trigger/main.cpp
@@ -0,0 +1,82 @@
+/*
+ * 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 <cutils/properties.h>
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <dirent.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include <climits>
+#include <string>
+
+// Taken from android::base, which wasn't available on platform versions
+// earlier than nougat.
+
+static bool ReadFdToString(int fd, std::string* content) {
+ content->clear();
+ char buf[BUFSIZ];
+ ssize_t n;
+ while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)))) > 0) {
+ content->append(buf, n);
+ }
+ return (n == 0) ? true : false;
+}
+
+static bool ReadFileToString(const std::string& path, std::string* content,
+ bool follow_symlinks) {
+ int flags = O_RDONLY | O_CLOEXEC | (follow_symlinks ? 0 : O_NOFOLLOW);
+ int fd = TEMP_FAILURE_RETRY(open(path.c_str(), flags));
+ if (fd == -1) {
+ return false;
+ }
+ bool result = ReadFdToString(fd, content);
+ close(fd);
+ return result;
+}
+
+int main(int argc __unused, char *argv[] __unused) {
+ const char sysfs_base[] = "/sys/class/virtio-ports/";
+ DIR *dir = opendir(sysfs_base);
+ if (dir) {
+ dirent *dp;
+ while ((dp = readdir(dir)) != nullptr) {
+ std::string dirname = dp->d_name;
+ std::string sysfs(sysfs_base + dirname + "/name");
+ struct stat st;
+ if (stat(sysfs.c_str(), &st)) {
+ continue;
+ }
+ std::string content;
+ if (!ReadFileToString(sysfs, &content, true)) {
+ continue;
+ }
+ if (content.empty()) {
+ continue;
+ }
+ content.erase(content.end() - 1);
+ // Leaves 32-11=22 characters for the port name from QEMU.
+ std::string propname("sys.cf.ser." + content);
+ std::string dev("/dev/" + dirname);
+ property_set(propname.c_str(), dev.c_str());
+ }
+ }
+ return 0;
+}
