WELCOMED-TODO

11 files changed, 543 insertions, 321 deletions

diff --git a/.gitignore b/.gitignore
index 4950d9656..2331d9a6b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -88,6 +88,7 @@
 /systemd-update-utmp
 /systemd-user-sessions
 /systemd-vconsole-setup
+/systemd-welcomed
 /tags
 /test-boot-timestamp
 /test-bus-chat
diff --git a/Makefile.am b/Makefile.am
index 9aa151537..670ae2884 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3979,19 +3979,21 @@ systemd_welcomed_SOURCES = \
 	src/welcome/welcomed.c \
 	src/welcome/welcomed-greeter.h \
 	src/welcome/welcomed-greeter.c \
-	src/welcome/welcomed-greeter-proto.c \
 	src/welcome/welcomed-greeter-screen.c \
 	src/welcome/welcomed-greeter-slave.c \
 	src/welcome/welcomed-greeter-view.c \
+	src/welcome/welcomed-proto.h \
+	src/welcome/welcomed-proto.c \
 	src/welcome/welcomed-session.c
 
 systemd_welcomed_CFLAGS = \
 	$(AM_CFLAGS)
 
 systemd_welcomed_LDADD = \
-	libsystemd-bus.la \
-	libsystemd-daemon.la \
+	libsystemd-bus-internal.la \
+	libsystemd-daemon-internal.la \
 	libsystemd-gfx.la \
+	libsystemd-login-internal.la \
 	libsystemd-shared.la
 endif
 
diff --git a/src/welcome/welcomed-greeter-proto.c b/src/welcome/welcomed-greeter-proto.c
deleted file mode 100644
index 2353c3343..000000000
--- a/src/welcome/welcomed-greeter-proto.c
+++ /dev/null
@@ -1,117 +0,0 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
-/***
-  This file is part of systemd.
-
-  Copyright 2013 David Herrmann <dh.herrmann@gmail.com>
-
-  systemd is free software; you can redistribute it and/or modify it
-  under the terms of the GNU Lesser General Public License as published by
-  the Free Software Foundation; either version 2.1 of the License, or
-  (at your option) any later version.
-
-  systemd is distributed in the hope that it will be useful, but
-  WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public License
-  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
-
-#include <errno.h>
-#include <stdbool.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "log.h"
-#include "macro.h"
-#include "sd-event.h"
-#include "util.h"
-#include "welcomed.h"
-#include "welcomed-greeter.h"
-
-static void greeter_proto_push(GreeterProto *p, GreeterMessage *msg) {
-        msg->next = NULL;
-        *p->out_last = msg;
-        p->out_last = &msg->next;
-
-        msg->next = *p->out_last;
-        msg->next = p->out_last;
-        p->out_last =
-}
-
-static GreeterMessage *greeter_proto_pop(GreeterProto *p) {
-        GreeterMessage *msg;
-
-        msg = p->out_first;
-        if (!msg)
-                return NULL;
-
-        p->out_first = msg->next;
-        if (!msg->next)
-                p->out_last = &p->out_first;
-
-        return msg;
-}
-
-static int greeter_proto_io_fn(sd_event_source *src, int fd, uint32_t mask, void *data) {
-        return 0;
-}
-
-static int greeter_proto_idle_fn(sd_event_source *src, void *data) {
-        return 0;
-}
-
-int greeter_proto_new(int comm,
-                      sd_event *event,
-                      greeter_proto_t proto_fn,
-                      void *data,
-                      GreeterProto **out) {
-        GreeterProto *p;
-        int r;
-
-        p = calloc(1, sizeof(*p));
-        if (!p)
-                goto oom;
-
-        p->out_last = &p->out_first;
-        p->comm = comm;
-        p->event = sd_event_ref(event);
-        p->proto_fn = proto_fn;
-        p->data = data;
-
-        r = sd_event_add_io(event,
-                            comm,
-                            EPOLLHUP | EPOLLERR | EPOLLIN | EPOLLOUT | EPOLLET,
-                            greeter_proto_io_fn,
-                            p,
-                            &p->comm_source);
-        if (r < 0) {
-                log_error("proto: cannot add comm-source: %d", r);
-                goto error;
-        }
-
-        *out = p;
-        return 0;
-
-oom:
-        r = log_oom();
-error:
-        greeter_proto_free(p);
-        return r;
-}
-
-void greeter_proto_free(GreeterProto *p) {
-        if (!p)
-                return;
-
-        sd_event_source_unref(p->comm_source);
-        sd_event_unref(p->event);
-        free(p);
-}
-
-void greeter_proto_send(GreeterProto *p, GreeterMessage *msg) {
-        msg->next = *p->out_last;
-        *p->out_last = msg;
-}
diff --git a/src/welcome/welcomed-greeter-slave.c b/src/welcome/welcomed-greeter-slave.c
index 315719afa..afe161a9b 100644
--- a/src/welcome/welcomed-greeter-slave.c
+++ b/src/welcome/welcomed-greeter-slave.c
@@ -29,10 +29,17 @@
 #include "macro.h"
 #include "sd-event.h"
 #include "util.h"
-#include "welcomed.h"
 #include "welcomed-greeter.h"
+#include "welcomed-proto.h"
 
-static void greeter_slave_proto_fn(GreeterProto *p, GreeterMessage *msg, void *data) {
+static void greeter_slave_proto_fn(Proto *p, ProtoMessage *msg, void *data) {
+        GreeterSlave *s = data;
+
+        if (!msg) {
+                log_notice("greeter: HUP on parent, exiting..");
+                sd_event_request_quit(s->event);
+                return;
+        }
 }
 
 static int greeter_slave_signal_fn(sd_event_source *src, const struct signalfd_siginfo *ssi, void *data) {
@@ -44,19 +51,7 @@ static int greeter_slave_signal_fn(sd_event_source *src, const struct signalfd_s
         return 0;
 }
 
-static void greeter_slave_free(GreeterSlave *s) {
-        unsigned int i;
-
-        if (!s)
-                return;
-
-        for (i = 0; s->sigs[i]; ++i)
-                sd_event_source_unref(s->sigs[i]);
-        sd_event_unref(s->event);
-        free(s);
-}
-
-static int greeter_slave_new(const char *seat, int comm, GreeterSlave **out) {
+int greeter_slave_new(const char *seat, int comm, GreeterSlave **out) {
         static const int sigs[] = {
                 SIGINT, SIGTERM, SIGQUIT, SIGHUP, SIGPIPE, SIGCHLD, 0
         };
@@ -92,7 +87,7 @@ static int greeter_slave_new(const char *seat, int comm, GreeterSlave **out) {
         }
         sigprocmask(SIG_BLOCK, &mask, NULL);
 
-        r = greeter_proto_new(comm, s->event, greeter_slave_proto_fn, s, &s->proto);
+        r = proto_new(comm, s->event, greeter_slave_proto_fn, s, &s->proto);
         if (r < 0)
                 goto error;
 
@@ -106,50 +101,22 @@ error:
         return r;
 }
 
-static int greeter_slave_run(GreeterSlave *s) {
-        return sd_event_loop(s->event);
-}
-
-int greeter_slave_spawn(const char *seat) {
-        int r, comm[2];
-        GreeterSlave *s;
-
-        r = socketpair(AF_UNIX, SOCK_SEQPACKET | SOCK_CLOEXEC | SOCK_NONBLOCK, 0, comm);
-        if (r < 0) {
-                r = -errno;
-                log_error("cannot create comm-sockets: %m");
-                return r;
-        }
-
-        r = fork();
-        if (r < 0) {
-                r = -errno;
-                log_error("cannot fork greeter process: %m");
-                close_nointr_nofail(comm[0]);
-                close_nointr_nofail(comm[1]);
-                return r;
-        } else if (!r) {
-                close_nointr_nofail(comm[0]);
-
-                /* TODO: do we wanna call log_close()/log_open() here?
-                 * Currently, we share the log with our parent. Not sure
-                 * whether that works with all the log backends. */
-
-                r = greeter_slave_new(seat, comm[1], &s);
-                if (r < 0) {
-                        log_error("greeter: setup failed: %d", r);
-                } else {
-                        r = greeter_slave_run(s);
-                        if (r < 0)
-                                log_error("greeter: runtime failure: %d", r);
+void greeter_slave_free(GreeterSlave *s) {
+        unsigned int i;
 
-                        greeter_slave_free(s);
-                }
+        if (!s)
+                return;
 
-                close_nointr_nofail(comm[1]);
-                _exit(r);
+        if (s->proto) {
+                proto_flush(s->proto);
+                proto_free(s->proto);
         }
+        for (i = 0; s->sigs[i]; ++i)
+                sd_event_source_unref(s->sigs[i]);
+        sd_event_unref(s->event);
+        free(s);
+}
 
-        close_nointr_nofail(comm[1]);
-        return comm[0];
+int greeter_slave_run(GreeterSlave *s) {
+        return sd_event_loop(s->event);
 }
diff --git a/src/welcome/welcomed-greeter.c b/src/welcome/welcomed-greeter.c
index 27c8721f3..daba97e26 100644
--- a/src/welcome/welcomed-greeter.c
+++ b/src/welcome/welcomed-greeter.c
@@ -25,6 +25,8 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
 #include <unistd.h>
 
 #include "def.h"
@@ -36,52 +38,47 @@
 #include "welcomed.h"
 #include "welcomed-greeter.h"
 
-static void greeter_proto_fn(GreeterProto *p, GreeterMessage *msg, void *data) {
-}
-
-int greeter_new(int comm, Manager *m, Greeter **out) {
-        Greeter *g;
-        int r;
-
-        g = calloc(1, sizeof(*g));
-        if (!g)
-                goto oom;
-
-        g->m = m;
-
-        r = greeter_proto_new(comm, m->event, greeter_proto_fn, g, &g->proto);
-        if (r < 0)
-                goto error;
-
-        *out = g;
-        return 0;
-
-oom:
-        r = log_oom();
-error:
-        greeter_free(g);
-        return r;
-}
-
-void greeter_free(Greeter *g) {
-        if (!g)
-                return;
-
-        greeter_stop(g);
-        greeter_proto_free(g->proto);
-        free(g);
-}
-
-void greeter_start(Greeter *g, const char *auto_session, const char *auto_user) {
-        if (g->running)
-                return;
-
-        g->running = 1;
-}
-
-void greeter_stop(Greeter *g) {
-        if (!g->running)
-                return;
-
-        g->running = 0;
+int greeter_spawn(const char *seat) {
+        int r, comm[2];
+        GreeterSlave *s;
+
+        /* we use MSG_DONTWAIT if required, so no SOCK_NONBLOCK here */
+        r = socketpair(AF_UNIX, SOCK_SEQPACKET | SOCK_CLOEXEC, 0, comm);
+        if (r < 0) {
+                r = -errno;
+                log_error("cannot create comm-sockets: %m");
+                return r;
+        }
+
+        r = fork();
+        if (r < 0) {
+                r = -errno;
+                log_error("cannot fork greeter process: %m");
+                close_nointr_nofail(comm[0]);
+                close_nointr_nofail(comm[1]);
+                return r;
+        } else if (!r) {
+                close_nointr_nofail(comm[0]);
+
+                /* TODO: do we wanna call log_close()/log_open() here?
+                 * Currently, we share the log with our parent. Not sure
+                 * whether that works with all the log backends. */
+
+                r = greeter_slave_new(seat, comm[1], &s);
+                if (r < 0) {
+                        log_error("greeter: setup failed: %d", r);
+                } else {
+                        r = greeter_slave_run(s);
+                        if (r < 0)
+                                log_error("greeter: runtime failure: %d", r);
+
+                        greeter_slave_free(s);
+                }
+
+                close_nointr_nofail(comm[1]);
+                _exit(r);
+        }
+
+        close_nointr_nofail(comm[1]);
+        return comm[0];
 }
diff --git a/src/welcome/welcomed-greeter.h b/src/welcome/welcomed-greeter.h
index 599e0049a..a86f3e6a1 100644
--- a/src/welcome/welcomed-greeter.h
+++ b/src/welcome/welcomed-greeter.h
@@ -28,32 +28,16 @@
 #include "list.h"
 #include "sd-event.h"
 #include "sd-gfx.h"
+#include "welcomed-proto.h"
 
-#define GREETER_ENTRY_MAX 512
-
-typedef struct GreeterMessage GreeterMessage;
-typedef struct GreeterProto GreeterProto;
 typedef struct GreeterSlave GreeterSlave;
 typedef struct GreeterView GreeterView;
 typedef struct GreeterScreen GreeterScreen;
 
-typedef void (*greeter_proto_t) (GreeterProto *p, GreeterMessage *m, void *data);
-
-struct GreeterProto {
-        int comm;
-        sd_event *event;
-        sd_event_source *comm_source;
-        greeter_proto_t proto_fn;
-        void *data;
-
-        GreeterMessage *out_first;
-        GreeterMessage **out_last;
-};
-
 struct GreeterSlave {
         sd_event *event;
         sd_event_source *sigs[_NSIG];
-        GreeterProto *proto;
+        Proto *proto;
 
         const char *seat;
 };
@@ -63,13 +47,13 @@ struct GreeterView {
 
         unsigned long age_cnt;
 
-        char username[GREETER_ENTRY_MAX];
+        char username[PROTO_ENTRY_MAX];
         unsigned long username_age;
 
-        char password[GREETER_ENTRY_MAX];
+        char password[PROTO_ENTRY_MAX];
         unsigned long password_age;
 
-        char message[GREETER_ENTRY_MAX];
+        char message[PROTO_ENTRY_MAX];
         unsigned long message_age;
 };
 
@@ -80,51 +64,11 @@ struct GreeterScreen {
         unsigned long fb_age[2];
 };
 
-/* greeter protocol */
-
-enum {
-        GREETER_START,
-        GREETER_STOP,
-        GREETER_LOGIN,
-        GREETER_SHOW_MESSAGE,
-};
-
-enum {
-        GREETER_MSG_SUCCESS,
-        GREETER_MSG_INTERNAL_ERROR,
-        GREETER_MSG_INVALID_USERNAME,
-        GREETER_MSG_WRONG_PASSWORD,
-};
-
-struct GreeterMessage {
-        GreeterMessage *next;
-        unsigned int type;
-
-        union {
-                struct GreeterMessageLogin {
-                        char name[GREETER_ENTRY_MAX];
-                        char password[GREETER_ENTRY_MAX];
-                } login;
-                struct GreeterMessageShowMessage {
-                        unsigned int msgid;
-                } show_message;
-        };
-};
-
-/* greeter proto */
-
-int greeter_proto_new(int comm,
-                      sd_event *event,
-                      greeter_proto_t proto_fn,
-                      void *data,
-                      GreeterProto **out);
-void greeter_proto_free(GreeterProto *p);
-
-void greeter_proto_send(GreeterProto *p, GreeterMessage *msg);
-
 /* greeter slave */
 
-int greeter_slave_spawn(const char *seat);
+int greeter_slave_new(const char *seat, int comm, GreeterSlave **out);
+void greeter_slave_free(GreeterSlave *s);
+int greeter_slave_run(GreeterSlave *s);
 
 /* greeter view */
 
diff --git a/src/welcome/welcomed-proto.c b/src/welcome/welcomed-proto.c
new file mode 100644
index 000000000..0e2f16298
--- /dev/null
+++ b/src/welcome/welcomed-proto.c
@@ -0,0 +1,265 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 David Herrmann <dh.herrmann@gmail.com>
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include "log.h"
+#include "macro.h"
+#include "sd-event.h"
+#include "util.h"
+#include "welcomed.h"
+#include "welcomed-proto.h"
+
+static void proto_push(Proto *p, ProtoMessage *msg) {
+        msg->next = NULL;
+        *p->out_last = msg;
+        p->out_last = &msg->next;
+}
+
+static ProtoMessage *proto_pop(Proto *p) {
+        ProtoMessage *msg;
+
+        if (!p->out_first)
+                return NULL;
+
+        msg = p->out_first;
+        p->out_first = msg->next;
+        if (!p->out_first)
+                p->out_last = &p->out_first;
+
+        return msg;
+}
+
+static ProtoMessage *proto_peek(Proto *p) {
+        return p->out_first;
+}
+
+static void proto_notify(Proto *p, ProtoMessage *msg) {
+        if (p->event_fn)
+                p->event_fn(p, msg, p->data);
+}
+
+static void proto_hup(Proto *p) {
+        proto_notify(p, NULL);
+}
+
+static int proto_read(Proto *p, int flags, ProtoMessage **out) {
+        ProtoMessage *msg, buf = { };
+        ssize_t r;
+
+try_again:
+        r = recv(p->comm, &buf, sizeof(buf), MSG_NOSIGNAL | flags);
+        if (r < 0) {
+                r = -errno;
+                if (r != -EAGAIN)
+                        p->hup = true;
+                return r;
+        } else if (!r) {
+                p->hup = true;
+                return -EAGAIN;
+        } else if (r < (ssize_t)PROTO_MESSAGE_SIZE_MIN) {
+                log_warning("proto: message with invalid size received");
+                goto try_again;
+        }
+
+        msg = proto_message_new(r, 0);
+        if (!msg) {
+                sd_event_source_set_enabled(p->idle_source, SD_EVENT_ONESHOT);
+                return log_oom();
+        }
+
+        memcpy(msg, &buf, r);
+
+        *out = msg;
+        return 0;
+}
+
+static int proto_read_many(Proto *p) {
+        ProtoMessage *msg;
+        int r;
+
+        /* Always try reading, don't test for HUP. In case a write() failed and
+         * caused a HUP, there might still be pending data that we want. */
+
+        do {
+                r = proto_read(p, MSG_DONTWAIT, &msg);
+                if (r >= 0) {
+                        proto_notify(p, msg);
+                        proto_message_free(msg);
+                }
+        } while (r >= 0);
+
+        return (r == -EAGAIN) ? 0 : r;
+}
+
+static int proto_write(Proto *p, ProtoMessage *msg, int flags) {
+        ssize_t r;
+
+        r = send(p->comm, msg, msg->size, MSG_NOSIGNAL | flags);
+        if (r < 0) {
+                r = -errno;
+                if (r != -EAGAIN)
+                        p->hup = true;
+
+                return r;
+        }
+
+        return 0;
+}
+
+static int proto_write_many(Proto *p) {
+        ProtoMessage *msg;
+        int r = 0;
+
+        /* If there's a HUP we have no reason to try writing more data.. */
+        if (p->hup)
+                return -EPIPE;
+
+        while ((msg = proto_peek(p))) {
+                r = proto_write(p, msg, MSG_DONTWAIT);
+                if (r < 0) {
+                        if (r == -EAGAIN)
+                                r = 0;
+                        break;
+                }
+
+                msg = proto_pop(p);
+                proto_message_free(msg);
+        }
+
+        return r;
+}
+
+static void proto_io(Proto *p, uint32_t mask) {
+        if (p->hup)
+                return;
+
+        if (mask & EPOLLOUT)
+                proto_write_many(p);
+
+        if (mask & EPOLLIN)
+                proto_read_many(p);
+
+        if (mask & (EPOLLHUP | EPOLLERR))
+                p->hup = true;
+
+        if (p->hup) {
+                sd_event_source_set_enabled(p->idle_source, SD_EVENT_OFF);
+                sd_event_source_set_enabled(p->comm_source, SD_EVENT_OFF);
+                proto_hup(p);
+        }
+}
+
+static int proto_io_fn(sd_event_source *src, int fd, uint32_t mask, void *data) {
+        proto_io(data, mask);
+        return 0;
+}
+
+static int proto_idle_fn(sd_event_source *src, void *data) {
+        proto_io(data, EPOLLOUT);
+        return 0;
+}
+
+int proto_new(int comm,
+              sd_event *event,
+              proto_event_t event_fn,
+              void *data,
+              Proto **out) {
+        Proto *p;
+        int r;
+
+        p = calloc(1, sizeof(*p));
+        if (!p)
+                goto oom;
+
+        p->out_last = &p->out_first;
+        p->comm = comm;
+        p->event = sd_event_ref(event);
+        p->event_fn = event_fn;
+        p->data = data;
+
+        r = sd_event_add_io(event,
+                            comm,
+                            EPOLLHUP | EPOLLERR | EPOLLIN | EPOLLOUT | EPOLLET,
+                            proto_io_fn,
+                            p,
+                            &p->comm_source);
+        if (r < 0)
+                goto error;
+
+        r = sd_event_add_defer(event, proto_idle_fn, p, &p->idle_source);
+        if (r < 0)
+                goto error;
+
+        sd_event_source_set_enabled(p->idle_source, SD_EVENT_OFF);
+
+        *out = p;
+        return 0;
+
+oom:
+        r = log_oom();
+error:
+        proto_free(p);
+        log_error("proto: cannot create proto object: %d", r);
+        return r;
+}
+
+void proto_free(Proto *p) {
+        ProtoMessage *msg;
+
+        if (!p)
+                return;
+
+        while ((msg = proto_pop(p)))
+                proto_message_free(msg);
+
+        sd_event_source_unref(p->idle_source);
+        sd_event_source_unref(p->comm_source);
+        sd_event_unref(p->event);
+        free(p);
+}
+
+void proto_send(Proto *p, ProtoMessage *msg) {
+        if (p->hup) {
+                proto_message_free(msg);
+        } else {
+                proto_push(p, msg);
+                sd_event_source_set_enabled(p->idle_source, SD_EVENT_ONESHOT);
+        }
+}
+
+void proto_flush(Proto *p) {
+        ProtoMessage *msg;
+        int r = p->hup ? -EPIPE : 0;
+
+        while ((msg = proto_pop(p))) {
+                /* try a synchronous write; no MSG_DONTWAIT */
+                if (r >= 0)
+                        r = proto_write(p, msg, 0);
+
+                proto_message_free(msg);
+        }
+}
diff --git a/src/welcome/welcomed-proto.h b/src/welcome/welcomed-proto.h
new file mode 100644
index 000000000..7fd41a134
--- /dev/null
+++ b/src/welcome/welcomed-proto.h
@@ -0,0 +1,124 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 David Herrmann <dh.herrmann@gmail.com>
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#pragma once
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <sys/types.h>
+
+#include "macro.h"
+#include "sd-event.h"
+#include "sd-gfx.h"
+#include "util.h"
+
+#define PROTO_ENTRY_MAX 512
+
+typedef struct Proto Proto;
+typedef struct ProtoMessage ProtoMessage;
+
+typedef void (*proto_event_t) (Proto *p, ProtoMessage *m, void *data);
+
+struct Proto {
+        int comm;
+        sd_event *event;
+        sd_event_source *comm_source;
+        sd_event_source *idle_source;
+        proto_event_t event_fn;
+        void *data;
+
+        ProtoMessage *out_first;
+        ProtoMessage **out_last;
+
+        bool hup : 1;
+};
+
+/* protocol */
+
+enum {
+        PROTO_START,
+        PROTO_STOP,
+        PROTO_LOGIN,
+        PROTO_SHOW_MESSAGE,
+};
+
+enum {
+        PROTO_MSG_SUCCESS,
+        PROTO_MSG_INTERNAL_ERROR,
+        PROTO_MSG_INVALID_USERNAME,
+        PROTO_MSG_WRONG_PASSWORD,
+};
+
+struct ProtoMessage {
+        ProtoMessage *next;
+        size_t size;
+        unsigned int type;
+
+        union {
+                int dummy;
+                struct ProtoMessageLogin {
+                        char name[PROTO_ENTRY_MAX];
+                        char password[PROTO_ENTRY_MAX];
+                } login;
+                struct ProtoMessageShowMessage {
+                        unsigned int msgid;
+                } show_message;
+        };
+};
+
+#define PROTO_MESSAGE_SIZE_MIN offsetof(ProtoMessage, dummy)
+
+static inline ProtoMessage *proto_message_new(size_t size, unsigned int type) {
+        ProtoMessage *msg;
+
+        size = MIN(size, PROTO_MESSAGE_SIZE_MIN);
+        msg = calloc(1, size);
+        if (!msg)
+                return NULL;
+
+        msg->size = size;
+        msg->type = type;
+        return msg;
+}
+
+static inline void proto_message_free(ProtoMessage *msg) {
+        free(msg);
+}
+
+#define proto_message_new_name(_name, _type) proto_message_new(sizeof(((ProtoMessage*)0)->_name), (_type))
+
+#define proto_message_new_start() proto_message_new(0, PROTO_START)
+#define proto_message_new_stop() proto_message_new(0, PROTO_STOP)
+#define proto_message_new_login() proto_message_new_name(login, PROTO_LOGIN)
+#define proto_message_new_show_message() proto_message_new_show_message(show_message, PROTO_SHOW_MESSAGE)
+
+/* proto helper */
+
+int proto_new(int comm,
+              sd_event *event,
+              proto_event_t event_fn,
+              void *data,
+              Proto **out);
+void proto_free(Proto *p);
+
+void proto_send(Proto *p, ProtoMessage *msg);
+void proto_flush(Proto *p);
diff --git a/src/welcome/welcomed-session.c b/src/welcome/welcomed-session.c
index b117bbf8a..7a1e0b81d 100644
--- a/src/welcome/welcomed-session.c
+++ b/src/welcome/welcomed-session.c
@@ -26,7 +26,12 @@
 
 #include "log.h"
 #include "macro.h"
-#include "sd-event.h"
 #include "util.h"
 #include "welcomed.h"
-#include "welcomed-greeter.h"
+
+int session_spawn(const char *seat,
+                  const char *session,
+                  const char *username,
+                  const char *password) {
+        return 0;
+}
diff --git a/src/welcome/welcomed.c b/src/welcome/welcomed.c
index 017219419..e3ea0d0ac 100644
--- a/src/welcome/welcomed.c
+++ b/src/welcome/welcomed.c
@@ -39,14 +39,42 @@
 #include "sd-bus.h"
 #include "sd-daemon.h"
 #include "sd-event.h"
+#include "sd-login.h"
 #include "util.h"
 #include "welcomed.h"
-#include "welcomed-greeter.h"
 
 static const char *arg_seat;
 static const char *arg_auto_session;
 static const char *arg_auto_user;
 
+static void manager_proto_fn(Proto *p, ProtoMessage *msg, void *data) {
+        Manager *m = data;
+
+        if (!msg) {
+                log_error("HUP on greeter slave, exiting..");
+                sd_event_request_quit(m->event);
+                return;
+        }
+}
+
+static void manager_start(Manager *m) {
+        if (m->running)
+                return;
+
+        log_info("Seat gained graphics-support; spawning greeter");
+
+        m->running = 1;
+}
+
+static void manager_stop(Manager *m) {
+        if (!m->running)
+                return;
+
+        log_info("Seat lost graphics-support; stopping greeter");
+
+        m->running = 0;
+}
+
 static int manager_adjust_state(Manager *m, bool sync) {
         _cleanup_bus_message_unref_ sd_bus_message *rep = NULL;
         _cleanup_bus_error_free_ sd_bus_error err = SD_BUS_ERROR_NULL;
@@ -82,13 +110,10 @@ static int manager_adjust_state(Manager *m, bool sync) {
                 m->can_graphical = v;
         }
 
-        if (m->can_graphical && !m->greeter->running) {
-                log_info("Seat gained graphics-support; spawning greeter");
-                greeter_start(m->greeter, arg_auto_session, arg_auto_user);
-        } else if (!m->can_graphical && m->greeter->running) {
-                log_info("Seat lost graphics-support; stopping greeter");
-                greeter_stop(m->greeter);
-        }
+        if (m->can_graphical)
+                manager_start(m);
+        else if (!m->can_graphical)
+                manager_stop(m);
 
         return 0;
 
@@ -133,7 +158,12 @@ static void manager_free(Manager *m) {
         if (!m)
                 return;
 
-        greeter_free(m->greeter);
+        manager_stop(m);
+
+        if (m->proto) {
+                proto_flush(m->proto);
+                proto_free(m->proto);
+        }
         sd_bus_unref(m->bus);
         for (i = 0; m->sigs[i]; ++i)
                 sd_event_source_unref(m->sigs[i]);
@@ -157,6 +187,7 @@ static int manager_new(int comm, Manager **out) {
                 goto oom;
 
         m->seat = arg_seat;
+        m->auto_done = !arg_auto_user;
 
         r = sd_event_default(&m->event);
         if (r < 0) {
@@ -214,7 +245,7 @@ static int manager_new(int comm, Manager **out) {
                 goto error;
         }
 
-        r = greeter_new(comm, m, &m->greeter);
+        r = proto_new(comm, m->event, manager_proto_fn, m, &m->proto);
         if (r < 0)
                 goto error;
 
@@ -266,7 +297,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "auto-user",    required_argument, NULL, ARG_AUTO_USER    },
                 {}
         };
-        int c;
+        int c, r;
 
         assert(argc >= 0);
         assert(argv);
@@ -303,6 +334,14 @@ static int parse_argv(int argc, char *argv[]) {
         if (!arg_seat) {
                 log_error("No seat specified via --seat=NAME.");
                 return -EINVAL;
+        } else {
+                r = sd_seat_can_multi_session(arg_seat);
+                if (r < 0) {
+                        log_error("Invalid seat: %s", arg_seat);
+                        return r;
+                } else if (!r) {
+                        log_warning("Multi-session not supported on seat %s", arg_seat);
+                }
         }
 
         if (isempty(arg_auto_session))
@@ -331,7 +370,7 @@ int main(int argc, char *argv[]) {
                 return EXIT_SUCCESS;
 
         /* fork off greeter-slave early so it has a clean environment */
-        comm = greeter_slave_spawn(arg_seat);
+        comm = greeter_spawn(arg_seat);
         if (comm < 0)
                 goto finish;
 
@@ -346,8 +385,7 @@ int main(int argc, char *argv[]) {
 finish:
         sd_notify(false, "STATUS=Shutting down...");
 
-        if (m)
-                manager_free(m);
+        manager_free(m);
         if (comm >= 0)
                 close_nointr(comm);
 
diff --git a/src/welcome/welcomed.h b/src/welcome/welcomed.h
index cd879b88e..c8c95a350 100644
--- a/src/welcome/welcomed.h
+++ b/src/welcome/welcomed.h
@@ -28,10 +28,9 @@
 #include "list.h"
 #include "sd-bus.h"
 #include "sd-event.h"
-#include "welcomed-greeter.h"
+#include "welcomed-proto.h"
 
 typedef struct Manager Manager;
-typedef struct Greeter Greeter;
 
 struct Manager {
         sd_event *event;
@@ -41,23 +40,20 @@ struct Manager {
         const char *seat;
         char *seat_path;
 
-        Greeter *greeter;
+        Proto *proto;
 
         bool can_graphical : 1;
-};
-
-struct Greeter {
-        Manager *m;
-        GreeterProto *proto;
-
-        unsigned int running : 1;
-        unsigned int auto_done : 1;
+        bool running : 1;
+        bool auto_done : 1;
 };
 
 /* greeter */
 
-int greeter_new(int comm, Manager *m, Greeter **out);
-void greeter_free(Greeter *g);
+int greeter_spawn(const char *seat);
+
+/* session */
 
-void greeter_start(Greeter *g, const char *auto_session, const char *auto_user);
-void greeter_stop(Greeter *g);
+int session_spawn(const char *seat,
+                  const char *session,
+                  const char *username,
+                  const char *password);