Refactor some packet-building for readability and safety
[oweals/dinit.git] / src / dinitctl.cc
index e8c5daa38385fb35b8a361b03f2a2f3e9dbfd6e7..f260bf0a9d0aa5d1a4f4708357b010e7845b8f31 100644 (file)
@@ -3,10 +3,14 @@
 #include <cstring>
 #include <string>
 #include <iostream>
+#include <fstream>
 #include <system_error>
 #include <memory>
+#include <algorithm>
 
 #include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <unistd.h>
 #include "control-cmds.h"
 #include "service-constants.h"
 #include "cpbuffer.h"
+#include "dinit-client.h"
+#include "load-service.h"
+#include "dinit-util.h"
+#include "mconfig.h"
 
 // dinitctl:  utility to control the Dinit daemon, including starting and stopping of services.
 
-// This utility communicates with the dinit daemon via a unix stream socket (/dev/initctl, or $HOME/.dinitctl).
+// This utility communicates with the dinit daemon via a unix stream socket (as specified in
+// SYSCONTROLSOCKET, or $HOME/.dinitctl).
 
-using handle_t = uint32_t;
+static constexpr uint16_t min_cp_version = 1;
+static constexpr uint16_t max_cp_version = 1;
 
+enum class command_t;
 
-class ReadCPException
-{
-    public:
-    int errcode;
-    ReadCPException(int err) : errcode(err) { }
-};
-
-enum class Command;
-
-static int issueLoadService(int socknum, const char *service_name);
-static int checkLoadReply(int socknum, cpbuffer<1024> &rbuffer, handle_t *handle_p, service_state_t *state_p);
-static int startStopService(int socknum, const char *service_name, Command command, bool do_pin, bool wait_for_service, bool verbose);
-static int unpinService(int socknum, const char *service_name, bool verbose);
-static int listServices(int socknum);
-
-
-// Fill a circular buffer from a file descriptor, reading at least _rlength_ bytes.
-// Throws ReadException if the requested number of bytes cannot be read, with:
-//     errcode = 0   if end of stream (remote end closed)
-//     errcode = errno   if another error occurred
-// Note that EINTR is ignored (i.e. the read will be re-tried).
-static void fillBufferTo(cpbuffer<1024> *buf, int fd, int rlength)
-{
-    do {
-        int r = buf->fill_to(fd, rlength);
-        if (r == -1) {
-            if (errno != EINTR) {
-                throw ReadCPException(errno);
-            }
-        }
-        else if (r == 0) {
-            throw ReadCPException(0);
-        }
-        else {
-            return;
-        }
-    }
-    while (true);
-}
+static int issue_load_service(int socknum, const char *service_name, bool find_only = false);
+static int check_load_reply(int socknum, cpbuffer_t &, handle_t *handle_p, service_state_t *state_p);
+static int start_stop_service(int socknum, cpbuffer_t &, const char *service_name, command_t command,
+        bool do_pin, bool do_force, bool wait_for_service, bool verbose);
+static int unpin_service(int socknum, cpbuffer_t &, const char *service_name, bool verbose);
+static int unload_service(int socknum, cpbuffer_t &, const char *service_name);
+static int list_services(int socknum, cpbuffer_t &);
+static int shutdown_dinit(int soclknum, cpbuffer_t &);
+static int add_remove_dependency(int socknum, cpbuffer_t &rbuffer, bool add, const char *service_from,
+        const char *service_to, dependency_type dep_type);
+static int enable_disable_service(int socknum, cpbuffer_t &rbuffer, const char *from, const char *to,
+        bool enable);
 
 static const char * describeState(bool stopped)
 {
@@ -74,61 +58,34 @@ static const char * describeVerb(bool stop)
     return stop ? "stop" : "start";
 }
 
-// Wait for a reply packet, skipping over any information packets
-// that are received in the meantime.
-static void wait_for_reply(cpbuffer<1024> &rbuffer, int fd)
-{
-    fillBufferTo(&rbuffer, fd, 1);
-    
-    while (rbuffer[0] >= 100) {
-        // Information packet; discard.
-        fillBufferTo(&rbuffer, fd, 1);
-        int pktlen = (unsigned char) rbuffer[1];
-        
-        rbuffer.consume(1);  // Consume one byte so we'll read one byte of the next packet
-        fillBufferTo(&rbuffer, fd, pktlen);
-        rbuffer.consume(pktlen - 1);
-    }
-}
-
-
-// Write *all* the requested buffer and re-try if necessary until
-// the buffer is written or an unrecoverable error occurs.
-static int write_all(int fd, const void *buf, size_t count)
-{
-    const char *cbuf = static_cast<const char *>(buf);
-    int w = 0;
-    while (count > 0) {
-        int r = write(fd, cbuf, count);
-        if (r == -1) {
-            if (errno == EINTR) continue;
-            return r;
-        }
-        w += r;
-        cbuf += r;
-        count -= r;
-    }
-    return w;
-}
-
-
-enum class Command {
+enum class command_t {
     NONE,
     START_SERVICE,
     WAKE_SERVICE,
     STOP_SERVICE,
+    RESTART_SERVICE,
     RELEASE_SERVICE,
     UNPIN_SERVICE,
-    LIST_SERVICES
+    UNLOAD_SERVICE,
+    LIST_SERVICES,
+    SHUTDOWN,
+    ADD_DEPENDENCY,
+    RM_DEPENDENCY,
+    ENABLE_SERVICE,
+    DISABLE_SERVICE
 };
 
+
 // Entry point.
 int main(int argc, char **argv)
 {
     using namespace std;
     
     bool show_help = argc < 2;
-    char *service_name = nullptr;
+    const char *service_name = nullptr;
+    const char *to_service_name = nullptr;
+    dependency_type dep_type;
+    bool dep_type_set = false;
     
     std::string control_socket_str;
     const char * control_socket_path = nullptr;
@@ -137,8 +94,9 @@ int main(int argc, char **argv)
     bool sys_dinit = false;  // communicate with system daemon
     bool wait_for_service = true;
     bool do_pin = false;
+    bool do_force = false;
     
-    Command command = Command::NONE;
+    command_t command = command_t::NONE;
         
     for (int i = 1; i < argc; i++) {
         if (argv[i][0] == '-') {
@@ -158,99 +116,202 @@ int main(int argc, char **argv)
             else if (strcmp(argv[i], "--pin") == 0) {
                 do_pin = true;
             }
+            else if (strcmp(argv[i], "--socket-path") == 0 || strcmp(argv[i], "-p") == 0) {
+                ++i;
+                if (i == argc) {
+                    cerr << "dinitctl: --socket-path/-p should be followed by socket path" << std::endl;
+                    return 1;
+                }
+                control_socket_str = argv[i];
+            }
+            else if ((command == command_t::ENABLE_SERVICE || command == command_t::DISABLE_SERVICE)
+                    && strcmp(argv[i], "--from") == 0) {
+                ++i;
+                if (i == argc) {
+                    cerr << "dinitctl: --from should be followed by a service name" << std::endl;
+                    return 1;
+                }
+                service_name = argv[i];
+            }
+            else if ((command == command_t::STOP_SERVICE || command == command_t::RESTART_SERVICE)
+                    && (strcmp(argv[i], "--force") == 0 || strcmp(argv[i], "-f") == 0)) {
+                do_force = true;
+            }
             else {
+                cerr << "dinitctl: unrecognized/invalid option: " << argv[i] << " (use --help for help)\n";
                 return 1;
             }
         }
-        else if (command == Command::NONE) {
+        else if (command == command_t::NONE) {
             if (strcmp(argv[i], "start") == 0) {
-                command = Command::START_SERVICE; 
+                command = command_t::START_SERVICE; 
             }
             else if (strcmp(argv[i], "wake") == 0) {
-                command = Command::WAKE_SERVICE;
+                command = command_t::WAKE_SERVICE;
             }
             else if (strcmp(argv[i], "stop") == 0) {
-                command = Command::STOP_SERVICE;
+                command = command_t::STOP_SERVICE;
+            }
+            else if (strcmp(argv[i], "restart") == 0) {
+                command = command_t::RESTART_SERVICE;
             }
             else if (strcmp(argv[i], "release") == 0) {
-                command = Command::RELEASE_SERVICE;
+                command = command_t::RELEASE_SERVICE;
             }
             else if (strcmp(argv[i], "unpin") == 0) {
-                command = Command::UNPIN_SERVICE;
+                command = command_t::UNPIN_SERVICE;
+            }
+            else if (strcmp(argv[i], "unload") == 0) {
+                command = command_t::UNLOAD_SERVICE;
             }
             else if (strcmp(argv[i], "list") == 0) {
-                command = Command::LIST_SERVICES;
+                command = command_t::LIST_SERVICES;
+            }
+            else if (strcmp(argv[i], "shutdown") == 0) {
+                command = command_t::SHUTDOWN;
+            }
+            else if (strcmp(argv[i], "add-dep") == 0) {
+                command = command_t::ADD_DEPENDENCY;
+            }
+            else if (strcmp(argv[i], "rm-dep") == 0) {
+                command = command_t::RM_DEPENDENCY;
+            }
+            else if (strcmp(argv[i], "enable") == 0) {
+                command = command_t::ENABLE_SERVICE;
+            }
+            else if (strcmp(argv[i], "disable") == 0) {
+                command = command_t::DISABLE_SERVICE;
             }
             else {
-                show_help = true;
-                break;
+                cerr << "dinitctl: unrecognized command: " << argv[i] << " (use --help for help)\n";
+                return 1;
             }
         }
         else {
-            // service name
-            if (service_name != nullptr) {
-                show_help = true;
-                break;
+            // service name / other non-option
+            if (command == command_t::ADD_DEPENDENCY || command == command_t::RM_DEPENDENCY) {
+                if (! dep_type_set) {
+                    if (strcmp(argv[i], "regular") == 0) {
+                       dep_type = dependency_type::REGULAR;
+                    }
+                    else if (strcmp(argv[i], "milestone") == 0) {
+                       dep_type = dependency_type::MILESTONE;
+                    }
+                    else if (strcmp(argv[i], "waits-for") == 0) {
+                       dep_type = dependency_type::WAITS_FOR;
+                    }
+                    else {
+                       show_help = true;
+                       break;
+                    }
+                    dep_type_set = true;
+                }
+                else if (service_name == nullptr) {
+                    service_name = argv[i];
+                }
+                else if (to_service_name == nullptr) {
+                    to_service_name = argv[i];
+                }
+                else {
+                    show_help = true;
+                    break;
+                }
+            }
+            else if (command == command_t::ENABLE_SERVICE || command == command_t::DISABLE_SERVICE) {
+                if (to_service_name != nullptr) {
+                    show_help = true;
+                    break;
+                }
+                to_service_name = argv[i];
+            }
+            else {
+                if (service_name != nullptr) {
+                    show_help = true;
+                    break;
+                }
+                service_name = argv[i];
+                // TODO support multiple services
             }
-            service_name = argv[i];
-            // TODO support multiple services
         }
     }
     
-    if (service_name != nullptr && command == Command::LIST_SERVICES) {
+    bool no_service_cmd = (command == command_t::LIST_SERVICES || command == command_t::SHUTDOWN);
+
+    if (command == command_t::ENABLE_SERVICE || command == command_t::DISABLE_SERVICE) {
+        show_help |= (to_service_name == nullptr);
+    }
+    else if ((service_name == nullptr && ! no_service_cmd) || command == command_t::NONE) {
         show_help = true;
     }
-    
-    if ((service_name == nullptr && command != Command::LIST_SERVICES) || command == Command::NONE) {
+
+    if (service_name != nullptr && no_service_cmd) {
+        show_help = true;
+    }
+
+    if ((command == command_t::ADD_DEPENDENCY || command == command_t::RM_DEPENDENCY)
+            && (! dep_type_set || service_name == nullptr || to_service_name == nullptr)) {
         show_help = true;
     }
 
     if (show_help) {
-        cout << "dinitctl:   control Dinit services" << endl;
-        
-        cout << "\nUsage:" << endl;
-        cout << "    dinitctl [options] start [options] <service-name> : start and activate service" << endl;
-        cout << "    dinitctl [options] stop [options] <service-name>  : stop service and cancel explicit activation" << endl;
-        cout << "    dinitctl [options] wake [options] <service-name>  : start but do not mark activated" << endl;
-        cout << "    dinitctl [options] release [options] <service-name> : release activation, stop if no dependents" << endl;
-        cout << "    dinitctl [options] unpin <service-name>           : un-pin the service (after a previous pin)" << endl;
-        cout << "    dinitctl list                                     : list loaded services" << endl;
-        
-        cout << "\nNote: An activated service continues running when its dependents stop." << endl;
-        
-        cout << "\nGeneral options:" << endl;
-        cout << "  -s, --system     : control system daemon instead of user daemon" << endl;
-        cout << "  --quiet          : suppress output (except errors)" << endl;
-        
-        cout << "\nCommand options:" << endl;
-        cout << "  --help           : show this help" << endl;
-        cout << "  --no-wait        : don't wait for service startup/shutdown to complete" << endl;
-        cout << "  --pin            : pin the service in the requested (started/stopped) state" << endl;
+        cout << "dinitctl:   control Dinit services\n"
+          "\n"
+          "Usage:\n"
+          "    dinitctl [options] start [options] <service-name>\n"
+          "    dinitctl [options] stop [options] <service-name>\n"
+          "    dinitctl [options] wake [options] <service-name>\n"
+          "    dinitctl [options] release [options] <service-name>\n"
+          "    dinitctl [options] unpin <service-name>\n"
+          "    dinitctl [options] unload <service-name>\n"
+          "    dinitctl [options] list\n"
+          "    dinitctl [options] shutdown\n"
+          "    dinitctl [options] add-dep <type> <from-service> <to-service>\n"
+          "    dinitctl [options] rm-dep <type> <from-service> <to-service>\n"
+          "    dinitctl [options] enable [--from <from-service>] <to-service>\n"
+          "    dinitctl [options] disable [--from <from-service>] <to-service>\n"
+          "\n"
+          "Note: An activated service continues running when its dependents stop.\n"
+          "\n"
+          "General options:\n"
+          "  --help           : show this help\n"
+          "  -s, --system     : control system daemon instead of user daemon\n"
+          "  --quiet          : suppress output (except errors)\n"
+          "  --socket-path <path>, -p <path>\n"
+          "                   : specify socket for communication with daemon\n"
+          "\n"
+          "Command options:\n"
+          "  --no-wait        : don't wait for service startup/shutdown to complete\n"
+          "  --pin            : pin the service in the requested state\n"
+          "  --force          : force stop even if dependents will be affected\n";
         return 1;
     }
     
     signal(SIGPIPE, SIG_IGN);
     
-    control_socket_path = "/dev/dinitctl";
-    
     // Locate control socket
-    if (! sys_dinit) {
-        char * userhome = getenv("HOME");
-        if (userhome == nullptr) {
-            struct passwd * pwuid_p = getpwuid(getuid());
-            if (pwuid_p != nullptr) {
-                userhome = pwuid_p->pw_dir;
+    if (! control_socket_str.empty()) {
+        control_socket_path = control_socket_str.c_str();
+    }
+    else {
+        control_socket_path = SYSCONTROLSOCKET; // default to system
+        if (! sys_dinit) {
+            char * userhome = getenv("HOME");
+            if (userhome == nullptr) {
+                struct passwd * pwuid_p = getpwuid(getuid());
+                if (pwuid_p != nullptr) {
+                    userhome = pwuid_p->pw_dir;
+                }
+            }
+
+            if (userhome != nullptr) {
+                control_socket_str = userhome;
+                control_socket_str += "/.dinitctl";
+                control_socket_path = control_socket_str.c_str();
+            }
+            else {
+                cerr << "Cannot locate user home directory (set HOME or check /etc/passwd file)" << endl;
+                return 1;
             }
-        }
-        
-        if (userhome != nullptr) {
-            control_socket_str = userhome;
-            control_socket_str += "/.dinitctl";
-            control_socket_path = control_socket_str.c_str();
-        }
-        else {
-            cerr << "Cannot locate user home directory (set HOME or check /etc/passwd file)" << endl;
-            return 1;
         }
     }
     
@@ -277,217 +338,349 @@ int main(int argc, char **argv)
         return 1;
     }
     
-    // TODO should start by querying protocol version
-    
-    if (command == Command::UNPIN_SERVICE) {
-        return unpinService(socknum, service_name, verbose);
+    try {
+        // Start by querying protocol version:
+        cpbuffer_t rbuffer;
+        check_protocol_version(min_cp_version, max_cp_version, rbuffer, socknum);
+
+        if (command == command_t::UNPIN_SERVICE) {
+            return unpin_service(socknum, rbuffer, service_name, verbose);
+        }
+        else if (command == command_t::UNLOAD_SERVICE) {
+            return unload_service(socknum, rbuffer, service_name);
+        }
+        else if (command == command_t::LIST_SERVICES) {
+            return list_services(socknum, rbuffer);
+        }
+        else if (command == command_t::SHUTDOWN) {
+            return shutdown_dinit(socknum, rbuffer);
+        }
+        else if (command == command_t::ADD_DEPENDENCY || command == command_t::RM_DEPENDENCY) {
+            return add_remove_dependency(socknum, rbuffer, command == command_t::ADD_DEPENDENCY,
+                    service_name, to_service_name, dep_type);
+        }
+        else if (command == command_t::ENABLE_SERVICE || command == command_t::DISABLE_SERVICE) {
+            // If only one service specified, assume that we enable for 'boot' service:
+            if (service_name == nullptr) {
+                service_name = "boot";
+            }
+            return enable_disable_service(socknum, rbuffer, service_name, to_service_name,
+                    command == command_t::ENABLE_SERVICE);
+        }
+        else {
+            return start_stop_service(socknum, rbuffer, service_name, command, do_pin, do_force,
+                    wait_for_service, verbose);
+        }
+    }
+    catch (cp_old_client_exception &e) {
+        std::cerr << "dinitctl: too old (server reports newer protocol version)" << std::endl;
+        return 1;
     }
-    else if (command == Command::LIST_SERVICES) {
-        return listServices(socknum);
+    catch (cp_old_server_exception &e) {
+        std::cerr << "dinitctl: server too old or protocol error" << std::endl;
+        return 1;
+    }
+    catch (cp_read_exception &e) {
+        cerr << "dinitctl: control socket read failure or protocol error" << endl;
+        return 1;
+    }
+    catch (cp_write_exception &e) {
+        cerr << "dinitctl: control socket write error: " << std::strerror(e.errcode) << endl;
+        return 1;
+    }
+}
+
+// Extract/read a string of specified length from the buffer/socket. The string is consumed
+// from the buffer.
+static std::string read_string(int socknum, cpbuffer_t &rbuffer, uint32_t length)
+{
+    int rb_len = rbuffer.get_length();
+    if (uint32_t(rb_len) >= length) {
+        std::string r = rbuffer.extract_string(0, length);
+        rbuffer.consume(length);
+        return r;
     }
 
-    return startStopService(socknum, service_name, command, do_pin, wait_for_service, verbose);
+    std::string r = rbuffer.extract_string(0, rb_len);
+    uint32_t rlen = length - rb_len;
+    uint32_t clen;
+    do {
+        rbuffer.reset();
+        rbuffer.fill(socknum);
+        char *bptr = rbuffer.get_ptr(0);
+        clen = rbuffer.get_length();
+        clen = std::min(clen, rlen);
+        r.append(bptr, clen);
+        rlen -= clen;
+    } while (rlen > 0);
+
+    rbuffer.consume(clen);
+
+    return r;
+}
+
+// Load a service: issue load command, wait for reply. Return true on success, display error message
+// and return false on failure.
+//      socknum  - the socket fd to communicate via
+//      rbuffer  - the buffer for communication
+//      name     - the name of the service to load
+//      handle   - where to store the handle of the loaded service
+//      state    - where to store the state of the loaded service (may be null).
+static bool load_service(int socknum, cpbuffer_t &rbuffer, const char *name, handle_t *handle,
+        service_state_t *state)
+{
+    // Load 'to' service:
+    if (issue_load_service(socknum, name)) {
+        return false;
+    }
+
+    wait_for_reply(rbuffer, socknum);
+
+    if (check_load_reply(socknum, rbuffer, handle, state) != 0) {
+        return false;
+    }
+
+    return true;
+}
+
+// Get the service name for a given handle, by querying the daemon.
+static std::string get_service_name(int socknum, cpbuffer_t &rbuffer, handle_t handle)
+{
+    auto m = membuf()
+            .append((char) DINIT_CP_QUERYSERVICENAME)
+            .append((char) 0)
+            .append(handle);
+    write_all_x(socknum, m);
+
+    wait_for_reply(rbuffer, socknum);
+
+    if (rbuffer[0] != DINIT_RP_SERVICENAME) {
+        throw cp_read_exception{0};
+    }
+
+    // 1 byte reserved
+    // uint16_t size
+    fill_buffer_to(rbuffer, socknum, 2 + sizeof(uint16_t));
+    uint16_t namesize;
+    rbuffer.extract(&namesize, 2, sizeof(uint16_t));
+    rbuffer.consume(2 + sizeof(uint16_t));
+
+    std::string name;
+
+    do {
+        if (rbuffer.get_length() == 0) {
+            rbuffer.fill(socknum);
+        }
+
+        size_t to_extract = std::min(size_t(rbuffer.get_length()), namesize - name.length());
+        size_t contiguous_len = rbuffer.get_contiguous_length(rbuffer.get_ptr(0));
+        if (contiguous_len <= to_extract) {
+            name.append(rbuffer.get_ptr(0), contiguous_len);
+            rbuffer.consume(contiguous_len);
+            name.append(rbuffer.get_ptr(0), to_extract - contiguous_len);
+            rbuffer.consume(to_extract - contiguous_len);
+        }
+        else {
+            name.append(rbuffer.get_ptr(0), to_extract);
+            rbuffer.consume(to_extract);
+            break;
+        }
+
+    } while (name.length() < namesize);
+
+    return name;
 }
 
 // Start/stop a service
-static int startStopService(int socknum, const char *service_name, Command command, bool do_pin, bool wait_for_service, bool verbose)
+static int start_stop_service(int socknum, cpbuffer_t &rbuffer, const char *service_name,
+        command_t command, bool do_pin, bool do_force, bool wait_for_service, bool verbose)
 {
     using namespace std;
 
-    bool do_stop = (command == Command::STOP_SERVICE || command == Command::RELEASE_SERVICE);
+    bool do_stop = (command == command_t::STOP_SERVICE || command == command_t::RELEASE_SERVICE);
+
+    service_state_t state;
+    handle_t handle;
     
-    if (issueLoadService(socknum, service_name)) {
+    if (! load_service(socknum, rbuffer, service_name, &handle, &state)) {
         return 1;
     }
 
-    // Now we expect a reply:
-    
-    try {
-        cpbuffer<1024> rbuffer;
-        wait_for_reply(rbuffer, socknum);
-        
-        service_state_t state;
-        //service_state_t target_state;
-        handle_t handle;
-        
-        if (checkLoadReply(socknum, rbuffer, &handle, &state) != 0) {
-            return 0;
-        }
-                
-        service_state_t wanted_state = do_stop ? service_state_t::STOPPED : service_state_t::STARTED;
-        int pcommand = 0;
-        switch (command) {
-        case Command::STOP_SERVICE:
+    service_state_t wanted_state = do_stop ? service_state_t::STOPPED : service_state_t::STARTED;
+    int pcommand = 0;
+    switch (command) {
+        case command_t::STOP_SERVICE:
+        case command_t::RESTART_SERVICE:  // stop, and then start
             pcommand = DINIT_CP_STOPSERVICE;
             break;
-        case Command::RELEASE_SERVICE:
+        case command_t::RELEASE_SERVICE:
             pcommand = DINIT_CP_RELEASESERVICE;
             break;
-        case Command::START_SERVICE:
+        case command_t::START_SERVICE:
             pcommand = DINIT_CP_STARTSERVICE;
             break;
-        case Command::WAKE_SERVICE:
+        case command_t::WAKE_SERVICE:
             pcommand = DINIT_CP_WAKESERVICE;
             break;
         default: ;
+    }
+
+    // Need to issue STOPSERVICE/STARTSERVICE
+    // We'll do this regardless of the current service state / target state, since issuing
+    // start/stop also sets or clears the "explicitly started" flag on the service.
+    {
+        char flags = (do_pin ? 1 : 0) | ((pcommand == DINIT_CP_STOPSERVICE && !do_force) ? 2 : 0);
+        if (command == command_t::RESTART_SERVICE) {
+            flags |= 4;
         }
-        
-        // Need to issue STOPSERVICE/STARTSERVICE
-        // We'll do this regardless of the current service state / target state, since issuing
-        // start/stop also sets or clears the "explicitly started" flag on the service.
-        {
-            int r;
-            
-            {
-                auto buf = new char[2 + sizeof(handle)];
-                unique_ptr<char[]> ubuf(buf);
-                
-                buf[0] = pcommand;
-                buf[1] = do_pin ? 1 : 0;
-                memcpy(buf + 2, &handle, sizeof(handle));
-                r = write_all(socknum, buf, 2 + sizeof(handle));
-            }
-            
-            if (r == -1) {
-                perror("dinitctl: write");
-                return 1;
-            }
-            
-            wait_for_reply(rbuffer, socknum);
-            if (rbuffer[0] == DINIT_RP_ALREADYSS) {
-                bool already = (state == wanted_state);
-                if (verbose) {
-                    cout << "Service " << (already ? "(already) " : "") << describeState(do_stop) << "." << endl;
-                }
-                return 0; // success!
-            }
-            if (rbuffer[0] != DINIT_RP_ACK) {
-                cerr << "dinitctl: Protocol error." << endl;
-                return 1;
+
+        auto m = membuf()
+                .append((char) pcommand)
+                .append(flags)
+                .append(handle);
+        write_all_x(socknum, m);
+
+        wait_for_reply(rbuffer, socknum);
+        auto reply_pkt_h = rbuffer[0];
+        rbuffer.consume(1); // consume header
+        if (reply_pkt_h == DINIT_RP_ALREADYSS) {
+            bool already = (state == wanted_state);
+            if (verbose) {
+                cout << "Service " << (already ? "(already) " : "")
+                        << describeState(do_stop) << "." << endl;
             }
-            rbuffer.consume(1);
+            return 0; // success!
         }
-        
-        if (! wait_for_service) {
-            if (verbose) {
-                cout << "Issued " << describeVerb(do_stop) << " command successfully." << endl;
+        if (reply_pkt_h == DINIT_RP_DEPENDENTS && pcommand == DINIT_CP_STOPSERVICE) {
+            cerr << "dinitctl: Cannot stop service due to the following dependents:\n"
+                    "(Only direct dependents are listed. Exercise caution before using '--force' !!)\n";
+            // size_t number, N * handle_t handles
+            size_t number;
+            rbuffer.fill_to(socknum, sizeof(number));
+            rbuffer.extract(&number, 0, sizeof(number));
+            rbuffer.consume(sizeof(number));
+            std::vector<handle_t> handles;
+            handles.reserve(number);
+            for (size_t i = 0; i < number; i++) {
+                handle_t handle;
+                rbuffer.fill_to(socknum, sizeof(handle_t));
+                rbuffer.extract(&handle, 0, sizeof(handle));
+                handles.push_back(handle);
+                rbuffer.consume(sizeof(handle));
+            }
+            // Print the directly affected dependents:
+            cerr << " ";
+            for (handle_t handle : handles) {
+                cerr << " " << get_service_name(socknum, rbuffer, handle);
             }
-            return 0;
+            cerr << "\n";
+            return 1;
         }
-        
-        service_event completionEvent;
-        service_event cancelledEvent;
-        
-        if (do_stop) {
-            completionEvent = service_event::STOPPED;
-            cancelledEvent = service_event::STOPCANCELLED;
+        if (reply_pkt_h != DINIT_RP_ACK && reply_pkt_h != DINIT_RP_ALREADYSS) {
+            cerr << "dinitctl: protocol error." << endl;
+            return 1;
         }
-        else {
-            completionEvent = service_event::STARTED;
-            cancelledEvent = service_event::STARTCANCELLED;
+    }
+
+    if (! wait_for_service) {
+        if (verbose) {
+            cout << "Issued " << describeVerb(do_stop) << " command successfully." << endl;
         }
-        
-        // Wait until service started:
-        int r = rbuffer.fill_to(socknum, 2);
-        while (r > 0) {
-            if (rbuffer[0] >= 100) {
-                int pktlen = (unsigned char) rbuffer[1];
-                fillBufferTo(&rbuffer, socknum, pktlen);
-                
-                if (rbuffer[0] == DINIT_IP_SERVICEEVENT) {
-                    handle_t ev_handle;
-                    rbuffer.extract((char *) &ev_handle, 2, sizeof(ev_handle));
-                    service_event event = static_cast<service_event>(rbuffer[2 + sizeof(ev_handle)]);
-                    if (ev_handle == handle) {
-                        if (event == completionEvent) {
-                            if (verbose) {
-                                cout << "Service " << describeState(do_stop) << "." << endl;
-                            }
-                            return 0;
+        return 0;
+    }
+
+    service_event_t completionEvent;
+    service_event_t cancelledEvent;
+
+    if (do_stop) {
+        completionEvent = service_event_t::STOPPED;
+        cancelledEvent = service_event_t::STOPCANCELLED;
+    }
+    else {
+        completionEvent = service_event_t::STARTED;
+        cancelledEvent = service_event_t::STARTCANCELLED;
+    }
+
+    // Wait until service started:
+    int r = rbuffer.fill_to(socknum, 2);
+    while (r > 0) {
+        if (rbuffer[0] >= 100) {
+            int pktlen = (unsigned char) rbuffer[1];
+            fill_buffer_to(rbuffer, socknum, pktlen);
+
+            if (rbuffer[0] == DINIT_IP_SERVICEEVENT) {
+                handle_t ev_handle;
+                rbuffer.extract((char *) &ev_handle, 2, sizeof(ev_handle));
+                service_event_t event = static_cast<service_event_t>(rbuffer[2 + sizeof(ev_handle)]);
+                if (ev_handle == handle) {
+                    if (event == completionEvent) {
+                        if (verbose) {
+                            cout << "Service " << describeState(do_stop) << "." << endl;
                         }
-                        else if (event == cancelledEvent) {
-                            if (verbose) {
-                                cout << "Service " << describeVerb(do_stop) << " cancelled." << endl;
-                            }
-                            return 1;
+                        return 0;
+                    }
+                    else if (event == cancelledEvent) {
+                        if (verbose) {
+                            cout << "Service " << describeVerb(do_stop) << " cancelled." << endl;
                         }
-                        else if (! do_stop && event == service_event::FAILEDSTART) {
-                            if (verbose) {
-                                cout << "Service failed to start." << endl;
-                            }
-                            return 1;
+                        return 1;
+                    }
+                    else if (! do_stop && event == service_event_t::FAILEDSTART) {
+                        if (verbose) {
+                            cout << "Service failed to start." << endl;
                         }
+                        return 1;
                     }
                 }
-                
-                rbuffer.consume(pktlen);
-                r = rbuffer.fill_to(socknum, 2);
-            }
-            else {
-                // Not an information packet?
-                cerr << "dinitctl: protocol error" << endl;
-                return 1;
             }
-        }
-        
-        if (r == -1) {
-            perror("dinitctl: read");
+
+            rbuffer.consume(pktlen);
+            r = rbuffer.fill_to(socknum, 2);
         }
         else {
-            cerr << "protocol error (connection closed by server)" << endl;
+            // Not an information packet?
+            cerr << "dinitctl: protocol error" << endl;
+            return 1;
         }
-        return 1;
     }
-    catch (ReadCPException &exc) {
-        cerr << "dinitctl: control socket read failure or protocol error" << endl;
-        return 1;
+
+    if (r == -1) {
+        perror("dinitctl: read");
     }
-    catch (std::bad_alloc &exc) {
-        cerr << "dinitctl: out of memory" << endl;
-        return 1;
+    else {
+        cerr << "protocol error (connection closed by server)" << endl;
     }
-    
-    return 0;
+    return 1;
 }
 
 // Issue a "load service" command (DINIT_CP_LOADSERVICE), without waiting for
 // a response. Returns 1 on failure (with error logged), 0 on success.
-static int issueLoadService(int socknum, const char *service_name)
+static int issue_load_service(int socknum, const char *service_name, bool find_only)
 {
-    using namespace std;
-    
     // Build buffer;
     uint16_t sname_len = strlen(service_name);
     int bufsize = 3 + sname_len;
-    int r;
     
-    {
-        // TODO: new: catch exception
-        unique_ptr<char[]> ubuf(new char[bufsize]);
-        auto buf = ubuf.get();
-        
-        buf[0] = DINIT_CP_LOADSERVICE;
-        memcpy(buf + 1, &sname_len, 2);
-        memcpy(buf + 3, service_name, sname_len);
-        
-        r = write_all(socknum, buf, bufsize);
-    }
-    
-    if (r == -1) {
-        perror("dinitctl: write");
-        return 1;
-    }
+    std::unique_ptr<char[]> ubuf(new char[bufsize]);
+    auto buf = ubuf.get();
+
+    buf[0] = find_only ? DINIT_CP_FINDSERVICE : DINIT_CP_LOADSERVICE;
+    memcpy(buf + 1, &sname_len, 2);
+    memcpy(buf + 3, service_name, sname_len);
+
+    write_all_x(socknum, buf, bufsize);
     
     return 0;
 }
 
 // Check that a "load service" reply was received, and that the requested service was found.
-static int checkLoadReply(int socknum, cpbuffer<1024> &rbuffer, handle_t *handle_p, service_state_t *state_p)
+//   state_p may be null.
+static int check_load_reply(int socknum, cpbuffer_t &rbuffer, handle_t *handle_p, service_state_t *state_p)
 {
     using namespace std;
     
     if (rbuffer[0] == DINIT_RP_SERVICERECORD) {
-        fillBufferTo(&rbuffer, socknum, 2 + sizeof(*handle_p));
+        fill_buffer_to(rbuffer, socknum, 2 + sizeof(*handle_p));
         rbuffer.extract((char *) handle_p, 2, sizeof(*handle_p));
         if (state_p) *state_p = static_cast<service_state_t>(rbuffer[1]);
         //target_state = static_cast<service_state_t>(rbuffer[2 + sizeof(handle)]);
@@ -495,144 +688,458 @@ static int checkLoadReply(int socknum, cpbuffer<1024> &rbuffer, handle_t *handle
         return 0;
     }
     else if (rbuffer[0] == DINIT_RP_NOSERVICE) {
-        cerr << "dinitctl: Failed to find/load service." << endl;
+        cerr << "dinitctl: failed to find/load service." << endl;
         return 1;
     }
     else {
-        cerr << "dinitctl: Protocol error." << endl;
+        cerr << "dinitctl: protocol error." << endl;
         return 1;
     }
 }
 
-static int unpinService(int socknum, const char *service_name, bool verbose)
+static int unpin_service(int socknum, cpbuffer_t &rbuffer, const char *service_name, bool verbose)
 {
     using namespace std;
+
+    handle_t handle;
     
     // Build buffer;
-    if (issueLoadService(socknum, service_name) == 1) {
+    if (! load_service(socknum, rbuffer, service_name, &handle, nullptr)) {
         return 1;
     }
-
-    // Now we expect a reply:
     
-    try {
-        cpbuffer<1024> rbuffer;
+    // Issue UNPIN command.
+    {
+        auto m = membuf()
+                .append<char>(DINIT_CP_UNPINSERVICE)
+                .append(handle);
+        write_all_x(socknum, m);
+        
         wait_for_reply(rbuffer, socknum);
+        if (rbuffer[0] != DINIT_RP_ACK) {
+            cerr << "dinitctl: protocol error." << endl;
+            return 1;
+        }
+        rbuffer.consume(1);
+    }
+
+    if (verbose) {
+        cout << "Service unpinned." << endl;
+    }
+    return 0;
+}
+
+static int unload_service(int socknum, cpbuffer_t &rbuffer, const char *service_name)
+{
+    using namespace std;
+
+    if (issue_load_service(socknum, service_name, true) == 1) {
+        return 1;
+    }
+
+    wait_for_reply(rbuffer, socknum);
+
+    handle_t handle;
+
+    if (rbuffer[0] == DINIT_RP_NOSERVICE) {
+        cerr << "dinitctl: service not loaded." << endl;
+        return 1;
+    }
+
+    if (check_load_reply(socknum, rbuffer, &handle, nullptr) != 0) {
+        return 1;
+    }
+
+    // Issue UNLOAD command.
+    {
+        auto m = membuf()
+                .append<char>(DINIT_CP_UNLOADSERVICE)
+                .append(handle);
+        write_all_x(socknum, m);
+
+        wait_for_reply(rbuffer, socknum);
+        if (rbuffer[0] == DINIT_RP_NAK) {
+            cerr << "dinitctl: Could not unload service; service not stopped, or is a dependency of "
+                    "other service." << endl;
+            return 1;
+        }
+        if (rbuffer[0] != DINIT_RP_ACK) {
+            cerr << "dinitctl: Protocol error." << endl;
+            return 1;
+        }
+        rbuffer.consume(1);
+    }
+
+    cout << "Service unloaded." << endl;
+    return 0;
+}
+
+static int list_services(int socknum, cpbuffer_t &rbuffer)
+{
+    using namespace std;
+    
+    char cmdbuf[] = { (char)DINIT_CP_LISTSERVICES };
+    write_all_x(socknum, cmdbuf, 1);
+
+    wait_for_reply(rbuffer, socknum);
+    while (rbuffer[0] == DINIT_RP_SVCINFO) {
+        int hdrsize = 8 + std::max(sizeof(int), sizeof(pid_t));
+        fill_buffer_to(rbuffer, socknum, hdrsize);
+        int nameLen = rbuffer[1];
+        service_state_t current = static_cast<service_state_t>(rbuffer[2]);
+        service_state_t target = static_cast<service_state_t>(rbuffer[3]);
+
+        int console_flags = rbuffer[4];
+        bool has_console = (console_flags & 2) != 0;
+        bool waiting_console = (console_flags & 1) != 0;
+        bool was_skipped = (console_flags & 4) != 0;
+
+        stopped_reason_t stop_reason = static_cast<stopped_reason_t>(rbuffer[5]);
+
+        pid_t service_pid;
+        int exit_status;
+        if (current != service_state_t::STOPPED) {
+            rbuffer.extract((char *)&service_pid, 8, sizeof(service_pid));
+        }
+        else {
+               rbuffer.extract((char *)&exit_status, 8, sizeof(exit_status));
+        }
+
+        fill_buffer_to(rbuffer, socknum, nameLen + hdrsize);
+
+        char *name_ptr = rbuffer.get_ptr(hdrsize);
+        int clength = std::min(rbuffer.get_contiguous_length(name_ptr), nameLen);
+
+        string name = string(name_ptr, clength);
+        name.append(rbuffer.get_buf_base(), nameLen - clength);
+
+        cout << "[";
+
+        cout << (target  == service_state_t::STARTED ? "{" : " ");
+        if (current == service_state_t::STARTED) {
+            cout << (was_skipped ? "s" : "+");
+        }
+        else {
+            cout << " ";
+        }
+        cout << (target  == service_state_t::STARTED ? "}" : " ");
         
-        handle_t handle;
+        if (current == service_state_t::STARTING) {
+            cout << "<<";
+        }
+        else if (current == service_state_t::STOPPING) {
+            cout << ">>";
+        }
+        else {
+            cout << "  ";
+        }
         
-        if (checkLoadReply(socknum, rbuffer, &handle, nullptr) != 0) {
-            return 1;
+        cout << (target  == service_state_t::STOPPED ? "{" : " ");
+        if (current == service_state_t::STOPPED) {
+            bool did_fail = false;
+            if (stop_reason == stopped_reason_t::TERMINATED) {
+                if (!WIFEXITED(exit_status) || WEXITSTATUS(exit_status) != 0) {
+                    did_fail = true;
+                }
+            }
+            else did_fail = (stop_reason != stopped_reason_t::NORMAL);
+
+            cout << (did_fail ? "X" : "-");
+        }
+        else {
+               cout << " ";
+        }
+        cout << (target == service_state_t::STOPPED ? "}" : " ");
+
+        cout << "] " << name;
+
+        if (current != service_state_t::STOPPED && service_pid != -1) {
+               cout << " (pid: " << service_pid << ")";
         }
         
-        // Issue UNPIN command.
-        {
-            int r;
-            
-            {
-                char *buf = new char[1 + sizeof(handle)];
-                unique_ptr<char[]> ubuf(buf);
-                buf[0] = DINIT_CP_UNPINSERVICE;
-                memcpy(buf + 1, &handle, sizeof(handle));
-                r = write_all(socknum, buf, 2 + sizeof(handle));
-            }
-            
-            if (r == -1) {
-                perror("dinitctl: write");
-                return 1;
+        if (current == service_state_t::STOPPED && stop_reason == stopped_reason_t::TERMINATED) {
+            if (WIFEXITED(exit_status)) {
+                cout << " (exit status: " << WEXITSTATUS(exit_status) << ")";
             }
-            
-            wait_for_reply(rbuffer, socknum);
-            if (rbuffer[0] != DINIT_RP_ACK) {
-                cerr << "dinitctl: Protocol error." << endl;
-                return 1;
+            else if (WIFSIGNALED(exit_status)) {
+                cout << " (signal: " << WTERMSIG(exit_status) << ")";
             }
-            rbuffer.consume(1);
         }
+
+        if (has_console) {
+               cout << " (has console)";
+        }
+        else if (waiting_console) {
+               cout << " (waiting for console)";
+        }
+
+        cout << endl;
+
+        rbuffer.consume(hdrsize + nameLen);
+        wait_for_reply(rbuffer, socknum);
     }
-    catch (ReadCPException &exc) {
-        cerr << "dinitctl: Control socket read failure or protocol error" << endl;
+
+    if (rbuffer[0] != DINIT_RP_LISTDONE) {
+        cerr << "dinitctl: Control socket protocol error" << endl;
         return 1;
     }
-    catch (std::bad_alloc &exc) {
-        cerr << "dinitctl: Out of memory" << endl;
+
+    return 0;
+}
+
+static int add_remove_dependency(int socknum, cpbuffer_t &rbuffer, bool add,
+        const char *service_from, const char *service_to, dependency_type dep_type)
+{
+    using namespace std;
+
+    handle_t from_handle;
+    handle_t to_handle;
+
+    if (! load_service(socknum, rbuffer, service_from, &from_handle, nullptr)
+            || ! load_service(socknum, rbuffer, service_to, &to_handle, nullptr)) {
         return 1;
     }
-    
-    if (verbose) {
-        cout << "Service unpinned." << endl;
+
+    auto m = membuf()
+            .append<char>(add ? (char)DINIT_CP_ADD_DEP : (char)DINIT_CP_REM_DEP)
+            .append(dep_type)
+            .append(from_handle)
+            .append(to_handle);
+    write_all_x(socknum, m);
+
+    wait_for_reply(rbuffer, socknum);
+
+    // check reply
+    if (rbuffer[0] == DINIT_RP_NAK) {
+        cerr << "dinitctl: Could not add dependency: circular dependency or wrong state" << endl;
+        return 1;
     }
+    if (rbuffer[0] != DINIT_RP_ACK) {
+        cerr << "dinitctl: Control socket protocol error" << endl;
+        return 1;
+    }
+
     return 0;
 }
 
-static int listServices(int socknum)
+static int shutdown_dinit(int socknum, cpbuffer_t &rbuffer)
 {
+    // TODO support no-wait option.
     using namespace std;
-    
+
+    auto m = membuf()
+            .append<char>(DINIT_CP_SHUTDOWN)
+            .append(static_cast<char>(shutdown_type_t::HALT));
+    write_all_x(socknum, m);
+
+    wait_for_reply(rbuffer, socknum);
+
+    if (rbuffer[0] != DINIT_RP_ACK) {
+        cerr << "dinitctl: Control socket protocol error" << endl;
+        return 1;
+    }
+
+    // Now wait for rollback complete, by waiting for the connection to close:
     try {
-        char cmdbuf[] = { (char)DINIT_CP_LISTSERVICES };
-        int r = write_all(socknum, cmdbuf, 1);
-        
-        if (r == -1) {
-            perror("dinitctl: write");
-            return 1;
+        while (true) {
+            wait_for_info(rbuffer, socknum);
+            rbuffer.consume(rbuffer[1]);
         }
-        
-        cpbuffer<1024> rbuffer;
-        wait_for_reply(rbuffer, socknum);
-        while (rbuffer[0] == DINIT_RP_SVCINFO) {
-            fillBufferTo(&rbuffer, socknum, 8);
-            int nameLen = rbuffer[1];
-            service_state_t current = static_cast<service_state_t>(rbuffer[2]);
-            service_state_t target = static_cast<service_state_t>(rbuffer[3]);
-            
-            fillBufferTo(&rbuffer, socknum, nameLen + 8);
-            
-            char *name_ptr = rbuffer.get_ptr(8);
-            int clength = std::min(rbuffer.get_contiguous_length(name_ptr), nameLen);
-            
-            string name = string(name_ptr, clength);
-            name.append(rbuffer.get_buf_base(), nameLen - clength);
-            
-            cout << "[";
-            
-            cout << (target  == service_state_t::STARTED ? "{" : " ");
-            cout << (current == service_state_t::STARTED ? "+" : " ");
-            cout << (target  == service_state_t::STARTED ? "}" : " ");
-            
-            if (current == service_state_t::STARTING) {
-                cout << "<<";
-            }
-            else if (current == service_state_t::STOPPING) {
-                cout << ">>";
+    }
+    catch (cp_read_exception &exc) {
+        // Assume that the connection closed.
+    }
+
+    return 0;
+}
+
+// exception for cancelling a service operation
+class service_op_cancel { };
+
+static int enable_disable_service(int socknum, cpbuffer_t &rbuffer, const char *from, const char *to,
+        bool enable)
+{
+    using namespace std;
+
+    service_state_t from_state = service_state_t::STARTED;
+    handle_t from_handle;
+
+    handle_t to_handle;
+
+    if (! load_service(socknum, rbuffer, from, &from_handle, &from_state)
+            || ! load_service(socknum, rbuffer, to, &to_handle, nullptr)) {
+        return 1;
+    }
+
+    // Get service load path
+    char buf[1] = { DINIT_CP_QUERY_LOAD_MECH };
+    write_all_x(socknum, buf, 1);
+
+    wait_for_reply(rbuffer, socknum);
+
+    if (rbuffer[0] != DINIT_RP_LOADER_MECH) {
+        cerr << "dinitctl: Control socket protocol error" << endl;
+        return 1;
+    }
+
+    // Packet type, load mechanism type, packet size:
+    fill_buffer_to(rbuffer, socknum, 2 + sizeof(uint32_t));
+
+    if (rbuffer[1] != SSET_TYPE_DIRLOAD) {
+        cerr << "dinitctl: unknown configuration, unable to load service descriptions" << endl;
+        return 1;
+    }
+
+    vector<string> paths;
+
+    uint32_t pktsize;
+    rbuffer.extract(&pktsize, 2, sizeof(uint32_t));
+
+    fill_buffer_to(rbuffer, socknum, 2 + sizeof(uint32_t) * 3); // path entries, cwd length
+
+    uint32_t path_entries;  // number of service directories
+    rbuffer.extract(&path_entries, 2 + sizeof(uint32_t), sizeof(uint32_t));
+
+    uint32_t cwd_len;
+    rbuffer.extract(&cwd_len, 2 + sizeof(uint32_t) * 2, sizeof(uint32_t));
+    rbuffer.consume(2 + sizeof(uint32_t) * 3);
+    pktsize -= 2 + sizeof(uint32_t) * 3;
+
+    // Read current working directory of daemon:
+    std::string dinit_cwd = read_string(socknum, rbuffer, cwd_len);
+
+    // dinit daemon base directory against which service paths are resolved is in dinit_cwd
+
+    for (int i = 0; i < (int)path_entries; i++) {
+        uint32_t plen;
+        fill_buffer_to(rbuffer, socknum, sizeof(uint32_t));
+        rbuffer.extract(&plen, 0, sizeof(uint32_t));
+        rbuffer.consume(sizeof(uint32_t));
+        paths.push_back(read_string(socknum, rbuffer, plen));
+    }
+
+    // all service directories are now in the 'paths' vector
+    // Load/read service description for 'from' service:
+
+    ifstream service_file;
+    string service_file_path;
+
+    for (std::string path : paths) {
+        string test_path = combine_paths(combine_paths(dinit_cwd, path.c_str()), from);
+
+        service_file.open(test_path.c_str(), ios::in);
+        if (service_file) {
+            service_file_path = test_path;
+            break;
+        }
+    }
+
+    if (! service_file) {
+        cerr << "dinitctl: could not locate service file for service '" << from << "'" << endl;
+        return 1;
+    }
+
+    // We now need to read the service file, identify the waits-for.d directory (bail out if more than one),
+    // make sure the service is not listed as a dependency individually.
+
+    string waits_for_d;
+
+    try {
+        process_service_file(from, service_file, [&](string &line, string &setting,
+                dinit_load::string_iterator i, dinit_load::string_iterator end) -> void {
+            if (setting == "waits-for" || setting == "depends-on" || setting == "depends-ms") {
+                string dname = dinit_load::read_setting_value(i, end);
+                if (dname == to) {
+                    // There is already a dependency
+                    cerr << "dinitctl: there is a fixed dependency to service '" << to
+                            << "' in the service description of '" << from << "'." << endl;
+                    throw service_op_cancel();
+                }
             }
-            else {
-                cout << "  ";
-            }
-            
-            cout << (target  == service_state_t::STOPPED ? "{" : " ");
-            cout << (current == service_state_t::STOPPED ? "-" : " ");
-            cout << (target  == service_state_t::STOPPED ? "}" : " ");
-            
-            cout << "] " << name << endl;
-            
-            rbuffer.consume(8 + nameLen);
-            wait_for_reply(rbuffer, socknum);
+            else if (setting == "waits-for.d") {
+                string dname = dinit_load::read_setting_value(i, end);
+                if (! waits_for_d.empty()) {
+                    cerr << "dinitctl: service '" << from << "' has multiple waits-for.d directories "
+                            << "specified in service description" << endl;
+                    throw service_op_cancel();
+                }
+                waits_for_d = std::move(dname);
+            }
+        });
+    }
+    catch (const service_op_cancel &cexc) {
+        return 1;
+    }
+
+    // If the from service has no waits-for.d specified, we can't continue
+    if (waits_for_d.empty()) {
+        cerr << "dinitctl: service '" << from << "' has no waits-for.d directory specified" << endl;
+        return 1;
+    }
+
+    // The waits-for.d path is relative to the service file path, combine:
+    string waits_for_d_full = combine_paths(parent_path(service_file_path), waits_for_d.c_str());
+
+    // check if dependency already exists
+    string dep_link_path = combine_paths(waits_for_d_full, to);
+    struct stat stat_buf;
+    if (lstat(dep_link_path.c_str(), &stat_buf) == -1) {
+        if (errno != ENOENT) {
+            cerr << "dinitctl: checking for existing dependency link: " << dep_link_path << ": "
+                    << strerror(errno) << endl;
+            return 1;
         }
-        
-        if (rbuffer[0] != DINIT_RP_LISTDONE) {
-            cerr << "dinitctl: Control socket protocol error" << endl;
+    }
+    else {
+        // dependency already exists
+        if (enable) {
+            cerr << "dinitctl: service already enabled." << endl;
             return 1;
         }
     }
-    catch (ReadCPException &exc) {
-        cerr << "dinitctl: Control socket read failure or protocol error" << endl;
+
+    // warn if 'from' service is not started
+    if (enable && from_state != service_state_t::STARTED) {
+        cerr << "dinitctl: warning: enabling dependency for non-started service" << endl;
+    }
+
+    // add/remove dependency
+    constexpr int enable_pktsize = 2 + sizeof(handle_t) * 2;
+    char cmdbuf[enable_pktsize] = { char(enable ? DINIT_CP_ENABLESERVICE : DINIT_CP_REM_DEP),
+            char(dependency_type::WAITS_FOR)};
+    memcpy(cmdbuf + 2, &from_handle, sizeof(from_handle));
+    memcpy(cmdbuf + 2 + sizeof(from_handle), &to_handle, sizeof(to_handle));
+    write_all_x(socknum, cmdbuf, enable_pktsize);
+
+    wait_for_reply(rbuffer, socknum);
+
+    // check reply
+    if (enable && rbuffer[0] == DINIT_RP_NAK) {
+        cerr << "dinitctl: Could not enable service: possible circular dependency" << endl;
         return 1;
     }
-    catch (std::bad_alloc &exc) {
-        cerr << "dinitctl: Out of memory" << endl;
+    if (rbuffer[0] != DINIT_RP_ACK) {
+        cerr << "dinitctl: Control socket protocol error" << endl;
         return 1;
     }
-    
+
+    // create link
+    if (enable) {
+        if (symlink((string("../") + to).c_str(), dep_link_path.c_str()) == -1) {
+            cerr << "dinitctl: Could not create symlink at " << dep_link_path << ": " << strerror(errno)
+                    << "\n" "dinitctl: Note: service was activated, but will not be enabled on restart."
+                    << endl;
+            return 1;
+        }
+    }
+    else {
+        if (unlink(dep_link_path.c_str()) == -1) {
+            cerr << "dinitctl: Could not unlink dependency entry " << dep_link_path << ": "
+                    << strerror(errno) << "\n"
+                    "dinitctl: Note: service was disabled, but will be re-enabled on restart." << endl;
+            return 1;
+        }
+    }
+
     return 0;
 }