bus: allow two different fds for input/output in sd_bus_set_fd()

This is useful so that we can speak D-Bus over a FIFO pair such as
stdin+stdout.

4 files changed, 103 insertions, 71 deletions

diff --git a/src/libsystemd-bus/bus-internal.h b/src/libsystemd-bus/bus-internal.h
index 0149604d2a..4997936fa9 100644
--- a/src/libsystemd-bus/bus-internal.h
+++ b/src/libsystemd-bus/bus-internal.h
@@ -74,7 +74,7 @@ enum bus_auth {
 struct sd_bus {
         unsigned n_ref;
         enum bus_state state;
-        int fd;
+        int input_fd, output_fd;
         int message_version;
 
         bool negotiate_fds:1;
diff --git a/src/libsystemd-bus/bus-socket.c b/src/libsystemd-bus/bus-socket.c
index fed1971ec7..9d08674bf7 100644
--- a/src/libsystemd-bus/bus-socket.c
+++ b/src/libsystemd-bus/bus-socket.c
@@ -88,7 +88,7 @@ static int bus_socket_write_auth(sd_bus *b) {
         mh.msg_iov = b->auth_iovec + b->auth_index;
         mh.msg_iovlen = ELEMENTSOF(b->auth_iovec) - b->auth_index;
 
-        k = sendmsg(b->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
+        k = sendmsg(b->output_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
         if (k < 0)
                 return errno == EAGAIN ? 0 : -errno;
 
@@ -463,7 +463,7 @@ static int bus_socket_read_auth(sd_bus *b) {
         mh.msg_control = &control;
         mh.msg_controllen = sizeof(control);
 
-        k = recvmsg(b->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
+        k = recvmsg(b->input_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
         if (k < 0)
                 return errno == EAGAIN ? 0 : -errno;
         if (k == 0)
@@ -515,12 +515,12 @@ static int bus_socket_setup(sd_bus *b) {
         /* Enable SO_PASSCRED + SO_PASSEC. We try this on any
          * socket, just in case. */
         enable = !b->bus_client;
-        setsockopt(b->fd, SOL_SOCKET, SO_PASSCRED, &enable, sizeof(enable));
-        setsockopt(b->fd, SOL_SOCKET, SO_PASSSEC, &enable, sizeof(enable));
+        setsockopt(b->input_fd, SOL_SOCKET, SO_PASSCRED, &enable, sizeof(enable));
+        setsockopt(b->input_fd, SOL_SOCKET, SO_PASSSEC, &enable, sizeof(enable));
 
         /* Increase the buffers to a MB */
-        fd_inc_rcvbuf(b->fd, 1024*1024);
-        fd_inc_sndbuf(b->fd, 1024*1024);
+        fd_inc_rcvbuf(b->input_fd, 1024*1024);
+        fd_inc_sndbuf(b->output_fd, 1024*1024);
 
         return 0;
 }
@@ -577,13 +577,17 @@ static int bus_socket_start_auth(sd_bus *b) {
         b->auth_timeout = now(CLOCK_MONOTONIC) + BUS_DEFAULT_TIMEOUT;
 
         sl = sizeof(domain);
-        r = getsockopt(b->fd, SOL_SOCKET, SO_DOMAIN, &domain, &sl);
-        if (r < 0)
-                return -errno;
-
-        if (domain != AF_UNIX)
+        r = getsockopt(b->input_fd, SOL_SOCKET, SO_DOMAIN, &domain, &sl);
+        if (r < 0 || domain != AF_UNIX)
                 b->negotiate_fds = false;
 
+        if (b->output_fd != b->input_fd) {
+                r = getsockopt(b->output_fd, SOL_SOCKET, SO_DOMAIN, &domain, &sl);
+                if (r < 0 || domain != AF_UNIX)
+                        b->negotiate_fds = false;
+        }
+
+
         if (b->is_server)
                 return bus_socket_read_auth(b);
         else
@@ -594,18 +598,21 @@ int bus_socket_connect(sd_bus *b) {
         int r;
 
         assert(b);
-        assert(b->fd < 0);
+        assert(b->input_fd < 0);
+        assert(b->output_fd < 0);
         assert(b->sockaddr.sa.sa_family != AF_UNSPEC);
 
-        b->fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
-        if (b->fd < 0)
+        b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (b->input_fd < 0)
                 return -errno;
 
+        b->output_fd = b->input_fd;
+
         r = bus_socket_setup(b);
         if (r < 0)
                 return r;
 
-        r = connect(b->fd, &b->sockaddr.sa, b->sockaddr_size);
+        r = connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size);
         if (r < 0) {
                 if (errno == EINPROGRESS)
                         return 1;
@@ -617,15 +624,16 @@ int bus_socket_connect(sd_bus *b) {
 }
 
 int bus_socket_exec(sd_bus *b) {
-        int s[2];
+        int s[2], r;
         pid_t pid;
 
         assert(b);
-        assert(b->fd < 0);
+        assert(b->input_fd < 0);
+        assert(b->output_fd < 0);
         assert(b->exec_path);
 
-        b->fd = socketpair(AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, s);
-        if (b->fd < 0)
+        r = socketpair(AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, s);
+        if (r < 0)
                 return -errno;
 
         pid = fork();
@@ -636,8 +644,9 @@ int bus_socket_exec(sd_bus *b) {
         if (pid == 0) {
                 /* Child */
 
-                close_all_fds(s, 2);
-                close_nointr_nofail(s[0]);
+                reset_all_signal_handlers();
+
+                close_all_fds(s+1, 1);
 
                 assert_se(dup3(s[1], STDIN_FILENO, 0) == STDIN_FILENO);
                 assert_se(dup3(s[1], STDOUT_FILENO, 0) == STDOUT_FILENO);
@@ -661,7 +670,7 @@ int bus_socket_exec(sd_bus *b) {
         }
 
         close_nointr_nofail(s[1]);
-        b->fd = s[0];
+        b->output_fd = b->input_fd = s[0];
 
         return bus_socket_start_auth(b);
 }
@@ -714,7 +723,7 @@ int bus_socket_write_message(sd_bus *bus, sd_bus_message *m, size_t *idx) {
         mh.msg_iov = iov;
         mh.msg_iovlen = m->n_iovec;
 
-        k = sendmsg(bus->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
+        k = sendmsg(bus->output_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
         if (k < 0)
                 return errno == EAGAIN ? 0 : -errno;
 
@@ -854,7 +863,7 @@ int bus_socket_read_message(sd_bus *bus, sd_bus_message **m) {
         mh.msg_control = &control;
         mh.msg_controllen = sizeof(control);
 
-        k = recvmsg(bus->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
+        k = recvmsg(bus->input_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
         if (k < 0)
                 return errno == EAGAIN ? 0 : -errno;
         if (k == 0)
@@ -924,7 +933,7 @@ int bus_socket_process_opening(sd_bus *b) {
         assert(b->state == BUS_OPENING);
 
         zero(p);
-        p.fd = b->fd;
+        p.fd = b->output_fd;
         p.events = POLLOUT;
 
         r = poll(&p, 1, 0);
@@ -934,7 +943,7 @@ int bus_socket_process_opening(sd_bus *b) {
         if (!(p.revents & (POLLOUT|POLLERR|POLLHUP)))
                 return 0;
 
-        r = getsockopt(b->fd, SOL_SOCKET, SO_ERROR, &error, &slen);
+        r = getsockopt(b->output_fd, SOL_SOCKET, SO_ERROR, &error, &slen);
         if (r < 0)
                 b->last_connect_error = errno;
         else if (error != 0)
diff --git a/src/libsystemd-bus/sd-bus.c b/src/libsystemd-bus/sd-bus.c
index a71d7b5d77..4f004add2e 100644
--- a/src/libsystemd-bus/sd-bus.c
+++ b/src/libsystemd-bus/sd-bus.c
@@ -48,8 +48,7 @@ static void bus_free(sd_bus *b) {
 
         assert(b);
 
-        if (b->fd >= 0)
-                close_nointr_nofail(b->fd);
+        sd_bus_close(b);
 
         free(b->rbuffer);
         free(b->unique_name);
@@ -101,7 +100,7 @@ int sd_bus_new(sd_bus **ret) {
                 return -ENOMEM;
 
         r->n_ref = 1;
-        r->fd = -1;
+        r->input_fd = r->output_fd = -1;
         r->message_version = 1;
         r->negotiate_fds = true;
 
@@ -137,15 +136,18 @@ int sd_bus_set_address(sd_bus *bus, const char *address) {
         return 0;
 }
 
-int sd_bus_set_fd(sd_bus *bus, int fd) {
+int sd_bus_set_fd(sd_bus *bus, int input_fd, int output_fd) {
         if (!bus)
                 return -EINVAL;
         if (bus->state != BUS_UNSET)
                 return -EPERM;
-        if (fd < 0)
+        if (input_fd < 0)
+                return -EINVAL;
+        if (output_fd < 0)
                 return -EINVAL;
 
-        bus->fd = fd;
+        bus->input_fd = input_fd;
+        bus->output_fd = output_fd;
         return 0;
 }
 
@@ -679,10 +681,7 @@ static int bus_start_address(sd_bus *b) {
         assert(b);
 
         for (;;) {
-                if (b->fd >= 0) {
-                        close_nointr_nofail(b->fd);
-                        b->fd = -1;
-                }
+                sd_bus_close(b);
 
                 if (b->sockaddr.sa.sa_family != AF_UNSPEC) {
 
@@ -720,15 +719,27 @@ static int bus_start_fd(sd_bus *b) {
         int r;
 
         assert(b);
+        assert(b->input_fd >= 0);
+        assert(b->output_fd >= 0);
 
-        r = fd_nonblock(b->fd, true);
+        r = fd_nonblock(b->input_fd, true);
         if (r < 0)
                 return r;
 
-        r = fd_cloexec(b->fd, true);
+        r = fd_cloexec(b->input_fd, true);
         if (r < 0)
                 return r;
 
+        if (b->input_fd != b->output_fd) {
+                r = fd_nonblock(b->output_fd, true);
+                if (r < 0)
+                        return r;
+
+                r = fd_cloexec(b->output_fd, true);
+                if (r < 0)
+                        return r;
+        }
+
         return bus_socket_take_fd(b);
 }
 
@@ -745,7 +756,7 @@ int sd_bus_start(sd_bus *bus) {
         if (bus->is_server && bus->bus_client)
                 return -EINVAL;
 
-        if (bus->fd >= 0)
+        if (bus->input_fd >= 0)
                 r = bus_start_fd(bus);
         else if (bus->address || bus->sockaddr.sa.sa_family != AF_UNSPEC || bus->exec_path)
                 r = bus_start_address(bus);
@@ -848,11 +859,13 @@ fail:
 void sd_bus_close(sd_bus *bus) {
         if (!bus)
                 return;
-        if (bus->fd < 0)
-                return;
 
-        close_nointr_nofail(bus->fd);
-        bus->fd = -1;
+        if (bus->input_fd >= 0)
+                close_nointr_nofail(bus->input_fd);
+        if (bus->output_fd >= 0 && bus->output_fd != bus->input_fd)
+                close_nointr_nofail(bus->output_fd);
+
+        bus->input_fd = bus->output_fd = -1;
 }
 
 sd_bus *sd_bus_ref(sd_bus *bus) {
@@ -882,7 +895,7 @@ int sd_bus_is_open(sd_bus *bus) {
         if (!bus)
                 return -EINVAL;
 
-        return bus->state != BUS_UNSET && bus->fd >= 0;
+        return bus->state != BUS_UNSET && bus->input_fd >= 0;
 }
 
 int sd_bus_can_send(sd_bus *bus, char type) {
@@ -890,7 +903,7 @@ int sd_bus_can_send(sd_bus *bus, char type) {
 
         if (!bus)
                 return -EINVAL;
-        if (bus->fd < 0)
+        if (bus->output_fd < 0)
                 return -ENOTCONN;
 
         if (type == SD_BUS_TYPE_UNIX_FD) {
@@ -941,7 +954,7 @@ static int dispatch_wqueue(sd_bus *bus) {
         assert(bus);
         assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
 
-        if (bus->fd < 0)
+        if (bus->output_fd < 0)
                 return -ENOTCONN;
 
         while (bus->wqueue_size > 0) {
@@ -984,7 +997,7 @@ static int dispatch_rqueue(sd_bus *bus, sd_bus_message **m) {
         assert(m);
         assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO);
 
-        if (bus->fd < 0)
+        if (bus->input_fd < 0)
                 return -ENOTCONN;
 
         if (bus->rqueue_size > 0) {
@@ -1020,7 +1033,7 @@ int sd_bus_send(sd_bus *bus, sd_bus_message *m, uint64_t *serial) {
                 return -EINVAL;
         if (bus->state == BUS_UNSET)
                 return -ENOTCONN;
-        if (bus->fd < 0)
+        if (bus->output_fd < 0)
                 return -ENOTCONN;
         if (!m)
                 return -EINVAL;
@@ -1129,7 +1142,7 @@ int sd_bus_send_with_reply(
                 return -EINVAL;
         if (bus->state == BUS_UNSET)
                 return -ENOTCONN;
-        if (bus->fd < 0)
+        if (bus->output_fd < 0)
                 return -ENOTCONN;
         if (!m)
                 return -EINVAL;
@@ -1211,7 +1224,7 @@ int bus_ensure_running(sd_bus *bus) {
 
         assert(bus);
 
-        if (bus->fd < 0)
+        if (bus->input_fd < 0)
                 return -ENOTCONN;
         if (bus->state == BUS_UNSET)
                 return -ENOTCONN;
@@ -1248,7 +1261,7 @@ int sd_bus_send_with_reply_and_block(
 
         if (!bus)
                 return -EINVAL;
-        if (bus->fd < 0)
+        if (bus->output_fd < 0)
                 return -ENOTCONN;
         if (bus->state == BUS_UNSET)
                 return -ENOTCONN;
@@ -1358,11 +1371,12 @@ int sd_bus_send_with_reply_and_block(
 int sd_bus_get_fd(sd_bus *bus) {
         if (!bus)
                 return -EINVAL;
-
-        if (bus->fd < 0)
+        if (bus->input_fd < 0)
                 return -ENOTCONN;
+        if (bus->input_fd != bus->output_fd)
+                return -EPERM;
 
-        return bus->fd;
+        return bus->input_fd;
 }
 
 int sd_bus_get_events(sd_bus *bus) {
@@ -1372,7 +1386,7 @@ int sd_bus_get_events(sd_bus *bus) {
                 return -EINVAL;
         if (bus->state == BUS_UNSET)
                 return -ENOTCONN;
-        if (bus->fd < 0)
+        if (bus->input_fd < 0)
                 return -ENOTCONN;
 
         if (bus->state == BUS_OPENING)
@@ -1403,7 +1417,7 @@ int sd_bus_get_timeout(sd_bus *bus, uint64_t *timeout_usec) {
                 return -EINVAL;
         if (bus->state == BUS_UNSET)
                 return -ENOTCONN;
-        if (bus->fd < 0)
+        if (bus->input_fd < 0)
                 return -ENOTCONN;
 
         if (bus->state == BUS_AUTHENTICATING) {
@@ -1824,7 +1838,7 @@ int sd_bus_process(sd_bus *bus, sd_bus_message **ret) {
 
         if (!bus)
                 return -EINVAL;
-        if (bus->fd < 0)
+        if (bus->input_fd < 0)
                 return -ENOTCONN;
 
         switch (bus->state) {
@@ -1859,14 +1873,14 @@ int sd_bus_process(sd_bus *bus, sd_bus_message **ret) {
 }
 
 static int bus_poll(sd_bus *bus, bool need_more, uint64_t timeout_usec) {
-        struct pollfd p;
-        int r, e;
+        struct pollfd p[2];
+        int r, e, n;
         struct timespec ts;
         usec_t until, m;
 
         assert(bus);
 
-        if (bus->fd < 0)
+        if (bus->input_fd < 0)
                 return -ENOTCONN;
 
         e = sd_bus_get_events(bus);
@@ -1882,19 +1896,28 @@ static int bus_poll(sd_bus *bus, bool need_more, uint64_t timeout_usec) {
         if (r == 0)
                 m = (uint64_t) -1;
         else {
-                usec_t n;
-                n = now(CLOCK_MONOTONIC);
-                m = until > n ? until - n : 0;
+                usec_t nw;
+                nw = now(CLOCK_MONOTONIC);
+                m = until > nw ? until - nw : 0;
         }
 
         if (timeout_usec != (uint64_t) -1 && (m == (uint64_t) -1 || timeout_usec < m))
                 m = timeout_usec;
 
         zero(p);
-        p.fd = bus->fd;
-        p.events = e;
+        p[0].fd = bus->input_fd;
+
+        if (bus->output_fd == bus->input_fd) {
+                p[0].events = e;
+                n = 1;
+        } else {
+                p[0].events = e & POLLIN;
+                p[1].fd = bus->output_fd;
+                p[1].events = e & POLLOUT;
+                n = 2;
+        }
 
-        r = ppoll(&p, 1, m == (uint64_t) -1 ? NULL : timespec_store(&ts, m), NULL);
+        r = ppoll(p, n, m == (uint64_t) -1 ? NULL : timespec_store(&ts, m), NULL);
         if (r < 0)
                 return -errno;
 
@@ -1907,7 +1930,7 @@ int sd_bus_wait(sd_bus *bus, uint64_t timeout_usec) {
                 return -EINVAL;
         if (bus->state == BUS_UNSET)
                 return -ENOTCONN;
-        if (bus->fd < 0)
+        if (bus->input_fd < 0)
                 return -ENOTCONN;
         if (bus->rqueue_size > 0)
                 return 0;
@@ -1922,7 +1945,7 @@ int sd_bus_flush(sd_bus *bus) {
                 return -EINVAL;
         if (bus->state == BUS_UNSET)
                 return -ENOTCONN;
-        if (bus->fd < 0)
+        if (bus->output_fd < 0)
                 return -ENOTCONN;
 
         r = bus_ensure_running(bus);
diff --git a/src/libsystemd-bus/test-bus-server.c b/src/libsystemd-bus/test-bus-server.c
index 2cb4157498..a594ce3157 100644
--- a/src/libsystemd-bus/test-bus-server.c
+++ b/src/libsystemd-bus/test-bus-server.c
@@ -53,7 +53,7 @@ static void *server(void *p) {
         assert_se(sd_id128_randomize(&id) >= 0);
 
         assert_se(sd_bus_new(&bus) >= 0);
-        assert_se(sd_bus_set_fd(bus, c->fds[0]) >= 0);
+        assert_se(sd_bus_set_fd(bus, c->fds[0], c->fds[0]) >= 0);
         assert_se(sd_bus_set_server(bus, 1, id) >= 0);
         assert_se(sd_bus_set_negotiate_fds(bus, c->server_negotiate_unix_fds) >= 0);
         assert_se(sd_bus_set_anonymous(bus, c->server_anonymous_auth) >= 0);
@@ -132,7 +132,7 @@ static int client(struct context *c) {
         int r;
 
         assert_se(sd_bus_new(&bus) >= 0);
-        assert_se(sd_bus_set_fd(bus, c->fds[1]) >= 0);
+        assert_se(sd_bus_set_fd(bus, c->fds[1], c->fds[1]) >= 0);
         assert_se(sd_bus_set_negotiate_fds(bus, c->client_negotiate_unix_fds) >= 0);
         assert_se(sd_bus_set_anonymous(bus, c->client_anonymous_auth) >= 0);
         assert_se(sd_bus_start(bus) >= 0);