Converts adbshell to c++
Bug: 111445481
Test: create host image, replace /usr/bin/adbshell with this and then
copy into ~/bin for vsoc-01
Change-Id: I29857d33915ef0f9c84edfa770d0da5e311360a9
diff --git a/host/commands/adbshell/main.cpp b/host/commands/adbshell/main.cpp
new file mode 100644
index 0000000..62a68de
--- /dev/null
+++ b/host/commands/adbshell/main.cpp
@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+/* Utility that uses an adb connection as the login shell. */
+
+#include <array>
+#include <cassert>
+#include <cstdio>
+#include <cstring>
+#include <string>
+#include <vector>
+#include <unistd.h>
+
+// Many of our users interact with CVDs via ssh. They expect to be able to
+// get an Android shell (as opposed to the host shell) with a single command.
+//
+// Our goals are to:
+//
+// * Allow the user to select which CVD to connect to
+//
+// * Avoid modifications to the host-side sshd and the protocol
+//
+// We accomplish this by using specialized accounts: vsoc-## and cvd-## and
+// specific Android serial numbers:
+//
+// The vsoc-01 account provides a host-side shell that controls the first CVD
+// The cvd-01 account is connected to the Andorid shell of the first CVD
+// The first CVD has a serial number of CUTTLEFISHCVD01
+//
+// The code in the commands/launch directory also follows these conventions by
+// default.
+//
+
+namespace {
+std::string InstanceNumberAsStr() {
+ static const char kUserPrefix[] = "cvd-";
+
+ std::string user{std::getenv("USER")};
+ return user.rfind(kUserPrefix, 0) == 0 // starts_with
+ ? user.substr(sizeof(kUserPrefix) - 1)
+ : "01";
+}
+
+int InstanceNumberAsInt() {
+ auto instance_str = InstanceNumberAsStr();
+ char* end{};
+ instance_str.push_back('\0');
+ auto result = static_cast<int>(std::strtol(&instance_str[0], &end, 10));
+ return *end || result < 1 ? 1 : result;
+}
+
+std::string TCPInstanceStr() {
+ static constexpr int kFirstPort = 6520;
+ const char kIPPrefix[] = "127.0.0.1:";
+
+ auto instance_port = InstanceNumberAsInt() - 1 + kFirstPort;
+ return std::string{kIPPrefix} + std::to_string(instance_port);
+}
+
+std::string USBInstanceStr() {
+ const char kSerialNumberPrefix[] = "CUTTLEFISHCVD";
+ std::string instance = InstanceNumberAsStr();
+ return std::string{kSerialNumberPrefix} + InstanceNumberAsStr();
+}
+
+std::string InstanceStr() {
+ std::string possible_device_names[] = {TCPInstanceStr(), USBInstanceStr()};
+
+ FILE* adb_devices_cmd_stream = popen("/usr/bin/adb devices", "r");
+ std::array<char, 128> line{};
+ while (fgets(line.data(), line.size(), adb_devices_cmd_stream) != nullptr) {
+ for (const auto& device_name : possible_device_names) {
+ if (std::string{line.data()}.find(device_name) != std::string::npos) {
+ return device_name;
+ }
+ }
+ }
+ return nullptr;
+}
+
+std::string VsocUserName() {
+ const char kVsocUserPrefix[] = "vsoc-";
+ auto num = InstanceNumberAsStr();
+ return std::string{kVsocUserPrefix} + num;
+}
+
+std::string VsocHomeAdbShellPath() {
+ return std::string{"/home/"} + VsocUserName() + "/bin/adbshell";
+}
+
+void TryExecHomeAdbShell(char* argv[]) {
+ auto home_shell = VsocHomeAdbShellPath();
+ if (access(home_shell.c_str(), X_OK) != -1 && home_shell != argv[0]) {
+ home_shell.push_back('\0');
+ argv[0] = &home_shell[0];
+ execv(argv[0], argv);
+ assert(0 && "execv() returned");
+ }
+}
+} // namespace
+
+int main(int argc, char* argv[]) {
+ TryExecHomeAdbShell(argv);
+ auto instance = InstanceStr();
+ std::vector<char*> new_argv = {
+ const_cast<char*>("/usr/bin/adb"), const_cast<char*>("-s"),
+ const_cast<char*>(instance.c_str()), const_cast<char*>("shell"),
+ const_cast<char*>("/system/bin/sh")};
+
+ // Some important data is lost before this point, and there are
+ // no great recovery options:
+ // * ssh with no arguments comes in with 1 arg of -adbshell. The command
+ // given above does the right thing if we don't invoke the shell.
+ if (argc == 1) {
+ new_argv.back() = nullptr;
+ }
+ // * simple shell commands come in with a -c and a single string. The
+ // problem here is that adb doesn't preserve spaces, so we need
+ // to do additional escaping. The best compromise seems to be to
+ // throw double quotes around each string.
+ for (int i = 1; i < argc; ++i) {
+ size_t buf_size = std::strlen(argv[i]) + 4;
+ new_argv.push_back(new char[buf_size]);
+ std::snprintf(new_argv.back(), buf_size, "\"%s\"", argv[i]);
+ }
+ //
+ // * scp seems to be pathologically broken when paths contain spaces.
+ // spaces aren't properly escaped by gcloud, so scp will fail with
+ // "scp: with ambiguous target." We might be able to fix this with
+ // some creative parsing of the arguments, but that seems like
+ // overkill.
+ new_argv.push_back(nullptr);
+ execv(new_argv[0], new_argv.data());
+ // This never should happen
+ return 2;
+}