Services: Renamed from Servers

It didn't feel right to have a "DHCPClient" in a "Servers" directory.
Rename this to Services to better reflect the type of programs we'll
be putting in there.

Services/SystemServer/Makefile

@@ -0,0 +1,13 @@
+OBJS = \
+    Service.o \
+    main.o
+
+PROGRAM = SystemServer
+
+LIB_DEPS = Core
+
+install:
+	mkdir -p ../../Root/usr/include/SystemServer/
+	cp *.h ../../Root/usr/include/SystemServer/
+
+include ../../Makefile.common

Services/SystemServer/Service.cpp

@@ -0,0 +1,365 @@
+/*
+ * Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Service.h"
+#include <AK/HashMap.h>
+#include <AK/JsonArray.h>
+#include <AK/JsonObject.h>
+#include <LibCore/ConfigFile.h>
+#include <LibCore/LocalSocket.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <libgen.h>
+#include <pwd.h>
+#include <sched.h>
+#include <stdio.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+struct UidAndGids {
+    uid_t uid;
+    gid_t gid;
+    Vector<gid_t> extra_gids;
+};
+
+static HashMap<String, UidAndGids>* s_user_map;
+static HashMap<pid_t, Service*> s_service_map;
+
+void Service::resolve_user()
+{
+    if (s_user_map == nullptr) {
+        s_user_map = new HashMap<String, UidAndGids>;
+        for (struct passwd* passwd = getpwent(); passwd; passwd = getpwent()) {
+            Vector<gid_t> extra_gids;
+            for (struct group* group = getgrent(); group; group = getgrent()) {
+                for (size_t m = 0; group->gr_mem[m]; ++m) {
+                    if (!strcmp(group->gr_mem[m], passwd->pw_name))
+                        extra_gids.append(group->gr_gid);
+                }
+            }
+            endgrent();
+            s_user_map->set(passwd->pw_name, { passwd->pw_uid, passwd->pw_gid, move(extra_gids) });
+        }
+        endpwent();
+    }
+
+    auto user = s_user_map->get(m_user);
+    if (!user.has_value()) {
+        dbg() << "Failed to resolve user name " << m_user;
+        ASSERT_NOT_REACHED();
+    }
+    m_uid = user.value().uid;
+    m_gid = user.value().gid;
+    m_extra_gids = user.value().extra_gids;
+}
+
+Service* Service::find_by_pid(pid_t pid)
+{
+    auto it = s_service_map.find(pid);
+    if (it == s_service_map.end())
+        return nullptr;
+    return (*it).value;
+}
+
+static int ensure_parent_directories(const char* path)
+{
+    ASSERT(path[0] == '/');
+
+    char* parent_buffer = strdup(path);
+    const char* parent = dirname(parent_buffer);
+
+    int rc = 0;
+    while (true) {
+        int rc = mkdir(parent, 0755);
+
+        if (rc == 0)
+            break;
+
+        if (errno != ENOENT)
+            break;
+
+        ensure_parent_directories(parent);
+    };
+
+    free(parent_buffer);
+    return rc;
+}
+
+void Service::setup_socket()
+{
+    ASSERT(!m_socket_path.is_null());
+    ASSERT(m_socket_fd == -1);
+
+    ensure_parent_directories(m_socket_path.characters());
+
+    // Note: we use SOCK_CLOEXEC here to make sure we don't leak every socket to
+    // all the clients. We'll make the one we do need to pass down !CLOEXEC later
+    // after forking off the process.
+    m_socket_fd = socket(AF_LOCAL, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
+    if (m_socket_fd < 0) {
+        perror("socket");
+        ASSERT_NOT_REACHED();
+    }
+
+    if (fchown(m_socket_fd, m_uid, m_gid) < 0) {
+        perror("fchown");
+        ASSERT_NOT_REACHED();
+    }
+
+    if (fchmod(m_socket_fd, m_socket_permissions) < 0) {
+        perror("fchmod");
+        ASSERT_NOT_REACHED();
+    }
+
+    auto socket_address = Core::SocketAddress::local(m_socket_path);
+    auto un = socket_address.to_sockaddr_un();
+    int rc = bind(m_socket_fd, (const sockaddr*)&un, sizeof(un));
+    if (rc < 0) {
+        perror("bind");
+        ASSERT_NOT_REACHED();
+    }
+
+    rc = listen(m_socket_fd, 16);
+    if (rc < 0) {
+        perror("listen");
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void Service::setup_notifier()
+{
+    ASSERT(m_lazy);
+    ASSERT(m_socket_fd >= 0);
+    ASSERT(!m_socket_notifier);
+
+    m_socket_notifier = Core::Notifier::construct(m_socket_fd, Core::Notifier::Event::Read, this);
+    m_socket_notifier->on_ready_to_read = [this] {
+        dbg() << "Ready to read on behalf of " << name();
+        remove_child(*m_socket_notifier);
+        m_socket_notifier = nullptr;
+        spawn();
+    };
+}
+
+void Service::activate()
+{
+    ASSERT(m_pid < 0);
+
+    if (m_lazy)
+        setup_notifier();
+    else
+        spawn();
+}
+
+void Service::spawn()
+{
+    dbg() << "Spawning " << name();
+
+    m_run_timer.start();
+    m_pid = fork();
+
+    if (m_pid < 0) {
+        perror("fork");
+        ASSERT_NOT_REACHED();
+    } else if (m_pid == 0) {
+        // We are the child.
+
+        if (!m_working_directory.is_null()) {
+            if (chdir(m_working_directory.characters()) < 0) {
+                perror("chdir");
+                ASSERT_NOT_REACHED();
+            }
+        }
+
+        struct sched_param p;
+        p.sched_priority = m_priority;
+        int rc = sched_setparam(0, &p);
+        if (rc < 0) {
+            perror("sched_setparam");
+            ASSERT_NOT_REACHED();
+        }
+
+        if (!m_stdio_file_path.is_null()) {
+            close(STDIN_FILENO);
+            int fd = open_with_path_length(m_stdio_file_path.characters(), m_stdio_file_path.length(), O_RDWR, 0);
+            ASSERT(fd <= 0);
+            if (fd < 0) {
+                perror("open");
+                ASSERT_NOT_REACHED();
+            }
+            dup2(STDIN_FILENO, STDOUT_FILENO);
+            dup2(STDIN_FILENO, STDERR_FILENO);
+
+            if (isatty(STDIN_FILENO)) {
+                ioctl(STDIN_FILENO, TIOCSCTTY);
+            }
+        } else {
+            if (isatty(STDIN_FILENO)) {
+                ioctl(STDIN_FILENO, TIOCNOTTY);
+            }
+            close(STDIN_FILENO);
+            close(STDOUT_FILENO);
+            close(STDERR_FILENO);
+
+            int fd = open("/dev/null", O_RDWR);
+            ASSERT(fd == STDIN_FILENO);
+            dup2(STDIN_FILENO, STDOUT_FILENO);
+            dup2(STDIN_FILENO, STDERR_FILENO);
+        }
+
+        if (!m_socket_path.is_null()) {
+            ASSERT(m_socket_fd > 2);
+            dup2(m_socket_fd, 3);
+            // The new descriptor is !CLOEXEC here.
+            // This is true even if m_socket_fd == 3.
+            setenv("SOCKET_TAKEOVER", "1", true);
+        }
+
+        if (!m_user.is_null()) {
+            if (setgid(m_gid) < 0 || setgroups(m_extra_gids.size(), m_extra_gids.data()) < 0 || setuid(m_uid) < 0) {
+                dbgprintf("Failed to drop privileges (GID=%u, UID=%u)\n", m_gid, m_uid);
+                exit(1);
+            }
+        }
+
+        char* argv[m_extra_arguments.size() + 2];
+        argv[0] = const_cast<char*>(m_executable_path.characters());
+        for (size_t i = 0; i < m_extra_arguments.size(); i++)
+            argv[i + 1] = const_cast<char*>(m_extra_arguments[i].characters());
+        argv[m_extra_arguments.size() + 1] = nullptr;
+
+        rc = execv(argv[0], argv);
+        perror("exec");
+        ASSERT_NOT_REACHED();
+    } else {
+        // We are the parent.
+        s_service_map.set(m_pid, this);
+    }
+}
+
+void Service::did_exit(int exit_code)
+{
+    ASSERT(m_pid > 0);
+
+    dbg() << "Service " << name() << " has exited with exit code " << exit_code;
+
+    s_service_map.remove(m_pid);
+    m_pid = -1;
+
+    if (!m_keep_alive)
+        return;
+
+    int run_time_in_msec = m_run_timer.elapsed();
+    bool exited_successfully = exit_code == 0;
+
+    if (!exited_successfully && run_time_in_msec < 1000) {
+        switch (m_restart_attempts) {
+        case 0:
+            dbg() << "Trying again";
+            break;
+        case 1:
+            dbg() << "Third time's a charm?";
+            break;
+        default:
+            dbg() << "Giving up on " << name() << ". Good luck!";
+            return;
+        }
+        m_restart_attempts++;
+    }
+
+    activate();
+}
+
+Service::Service(const Core::ConfigFile& config, const StringView& name)
+    : Core::Object(nullptr)
+{
+    ASSERT(config.has_group(name));
+
+    set_name(name);
+    m_executable_path = config.read_entry(name, "Executable", String::format("/bin/%s", this->name().characters()));
+    m_extra_arguments = config.read_entry(name, "Arguments", "").split(' ');
+    m_stdio_file_path = config.read_entry(name, "StdIO");
+
+    String prio = config.read_entry(name, "Priority");
+    if (prio == "low")
+        m_priority = 10;
+    else if (prio == "normal" || prio.is_null())
+        m_priority = 30;
+    else if (prio == "high")
+        m_priority = 50;
+    else
+        ASSERT_NOT_REACHED();
+
+    m_keep_alive = config.read_bool_entry(name, "KeepAlive");
+    m_lazy = config.read_bool_entry(name, "Lazy");
+
+    m_user = config.read_entry(name, "User");
+    if (!m_user.is_null())
+        resolve_user();
+
+    m_socket_path = config.read_entry(name, "Socket");
+    if (!m_socket_path.is_null()) {
+        auto socket_permissions_string = config.read_entry(name, "SocketPermissions", "0600");
+        m_socket_permissions = strtol(socket_permissions_string.characters(), nullptr, 8) & 04777;
+        setup_socket();
+    }
+
+    m_working_directory = config.read_entry(name, "WorkingDirectory");
+}
+
+void Service::save_to(JsonObject& json)
+{
+    Core::Object::save_to(json);
+
+    json.set("executable_path", m_executable_path);
+
+    // FIXME: This crashes Inspector.
+    /*
+    JsonArray extra_args;
+    for (String& arg : m_extra_arguments)
+        extra_args.append(arg);
+    json.set("extra_arguments", move(extra_args));
+    */
+
+    json.set("stdio_file_path", m_stdio_file_path);
+    json.set("priority", m_priority);
+    json.set("keep_alive", m_keep_alive);
+    json.set("socket_path", m_socket_path);
+    json.set("socket_permissions", m_socket_permissions);
+    json.set("lazy", m_lazy);
+    json.set("user", m_user);
+    json.set("uid", m_uid);
+    json.set("gid", m_gid);
+
+    if (m_pid > 0)
+        json.set("pid", m_pid);
+    else
+        json.set("pid", nullptr);
+
+    json.set("restart_attempts", m_restart_attempts);
+    json.set("working_directory", m_working_directory);
+}

Services/SystemServer/Service.h

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/RefPtr.h>
+#include <AK/String.h>
+#include <LibCore/ElapsedTimer.h>
+#include <LibCore/Notifier.h>
+#include <LibCore/Object.h>
+
+class Service final : public Core::Object {
+    C_OBJECT(Service)
+
+public:
+    void activate();
+    void did_exit(int exit_code);
+
+    static Service* find_by_pid(pid_t);
+
+    void save_to(AK::JsonObject&) override;
+
+private:
+    Service(const Core::ConfigFile&, const StringView& name);
+
+    void spawn();
+
+    // Path to the executable. By default this is /bin/{m_name}.
+    String m_executable_path;
+    // Extra arguments, starting from argv[1], to pass when exec'ing.
+    Vector<String> m_extra_arguments;
+    // File path to open as stdio fds.
+    String m_stdio_file_path;
+    int m_priority { 1 };
+    // Whether we should re-launch it if it exits.
+    bool m_keep_alive { false };
+    // Path to the socket to create and listen on on behalf of this service.
+    String m_socket_path;
+    // File system permissions for the socket.
+    mode_t m_socket_permissions { 0 };
+    // Whether we should only spawn this service once somebody connects to the socket.
+    bool m_lazy;
+    // The name of the user we should run this service as.
+    String m_user;
+    uid_t m_uid { 0 };
+    gid_t m_gid { 0 };
+    Vector<gid_t> m_extra_gids;
+
+    // PID of the running instance of this service.
+    pid_t m_pid { -1 };
+    // An open fd to the socket.
+    int m_socket_fd { -1 };
+    RefPtr<Core::Notifier> m_socket_notifier;
+
+    // Timer since we last spawned the service.
+    Core::ElapsedTimer m_run_timer;
+    // How many times we have tried to restart this service, only counting those
+    // times where it has exited unsuccessfully and too quickly.
+    int m_restart_attempts { 0 };
+
+    // The working directory in which to spawn the service
+    String m_working_directory;
+
+    void resolve_user();
+    void setup_socket();
+    void setup_notifier();
+};

Services/SystemServer/main.cpp

@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Service.h"
+#include <AK/Assertions.h>
+#include <AK/ByteBuffer.h>
+#include <LibCore/ConfigFile.h>
+#include <LibCore/Event.h>
+#include <LibCore/EventLoop.h>
+#include <LibCore/File.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+static void sigchld_handler(int)
+{
+    int status = 0;
+    pid_t pid = waitpid(-1, &status, WNOHANG);
+    if (!pid)
+        return;
+
+    dbg() << "Reaped child with pid " << pid;
+    Service* service = Service::find_by_pid(pid);
+    if (service == nullptr) {
+        dbg() << "There was no service with this pid, what is going on?";
+        return;
+    }
+
+    // Call service->did_exit(status) some time soon.
+    // We wouldn't want to run the complex logic, such
+    // as possibly spawning the service again, from the
+    // signal handler, so defer it.
+    Core::EventLoop::main().post_event(*service, make<Core::DeferredInvocationEvent>([=](auto&) {
+        service->did_exit(status);
+    }));
+    Core::EventLoop::wake();
+}
+
+static void check_for_test_mode()
+{
+    auto f = Core::File::construct("/proc/cmdline");
+    if (!f->open(Core::IODevice::ReadOnly)) {
+        dbg() << "Failed to read command line: " << f->error_string();
+        ASSERT(false);
+    }
+    const String cmd = String::copy(f->read_all());
+    dbg() << "Read command line: " << cmd;
+    if (cmd.matches("*testmode=1*")) {
+        // Eventually, we should run a test binary and wait for it to finish
+        // before shutting down. But this is good enough for now.
+        dbg() << "Waiting for testmode shutdown...";
+        sleep(5);
+        dbg() << "Shutting down due to testmode...";
+        if (fork() == 0) {
+            execl("/bin/shutdown", "/bin/shutdown", "-n", nullptr);
+            ASSERT_NOT_REACHED();
+        }
+    } else {
+        dbg() << "Continuing normally";
+    }
+}
+
+static void mount_all_filesystems()
+{
+    dbg() << "Spawning mount -a to mount all filesystems.";
+    pid_t pid = fork();
+
+    if (pid < 0) {
+        perror("fork");
+        ASSERT_NOT_REACHED();
+    } else if (pid == 0) {
+        execl("/bin/mount", "mount", "-a", nullptr);
+        perror("exec");
+        ASSERT_NOT_REACHED();
+    } else {
+        wait(nullptr);
+    }
+}
+
+int main(int, char**)
+{
+    if (pledge("stdio proc exec tty accept unix rpath wpath cpath chown fattr id", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    mount_all_filesystems();
+
+    struct sigaction sa = {
+        .sa_handler = sigchld_handler,
+        .sa_mask = 0,
+        .sa_flags = SA_RESTART
+    };
+    sigaction(SIGCHLD, &sa, nullptr);
+
+    Core::EventLoop event_loop;
+
+    // Read our config and instantiate services.
+    // This takes care of setting up sockets.
+    NonnullRefPtrVector<Service> services;
+    auto config = Core::ConfigFile::get_for_system("SystemServer");
+    for (auto name : config->groups())
+        services.append(Service::construct(*config, name));
+
+    // After we've set them all up, activate them!
+    for (auto& service : services)
+        service.activate();
+
+    // This won't return if we're in test mode.
+    check_for_test_mode();
+
+    return event_loop.exec();
+}