sd-bus: do not connect to dbus-1 socket when kdbus is available

We should not fall back to dbus-1 and connect to the proxy when kdbus
returns an error that indicates that kdbus is running but just does not
accept new connections because of quota limits or something similar.

Using is_kdbus_available() in libsystemd/ requires it to move from
shared/ to libsystemd/.

Based on a patch from David Herrmann:
  https://github.com/systemd/systemd/pull/886

21 files changed, 79 insertions, 24 deletions

diff --git a/src/libsystemd/sd-bus/bus-control.c b/src/libsystemd/sd-bus/bus-control.c
index 773c264cf0..92b12f2ae8 100644
--- a/src/libsystemd/sd-bus/bus-control.c
+++ b/src/libsystemd/sd-bus/bus-control.c
@@ -32,7 +32,6 @@
 #include "bus-message.h"
 #include "bus-control.h"
 #include "bus-bloom.h"
-#include "bus-util.h"
 #include "capability.h"
 
 _public_ int sd_bus_get_unique_name(sd_bus *bus, const char **unique) {
diff --git a/src/libsystemd/sd-bus/bus-convenience.c b/src/libsystemd/sd-bus/bus-convenience.c
index dfd82e746d..87898449e6 100644
--- a/src/libsystemd/sd-bus/bus-convenience.c
+++ b/src/libsystemd/sd-bus/bus-convenience.c
@@ -22,7 +22,6 @@
 #include "bus-internal.h"
 #include "bus-message.h"
 #include "bus-signature.h"
-#include "bus-util.h"
 #include "bus-type.h"
 
 _public_ int sd_bus_emit_signal(
diff --git a/src/libsystemd/sd-bus/bus-creds.c b/src/libsystemd/sd-bus/bus-creds.c
index 1c365b7fcd..130fbf7a23 100644
--- a/src/libsystemd/sd-bus/bus-creds.c
+++ b/src/libsystemd/sd-bus/bus-creds.c
@@ -31,10 +31,10 @@
 #include "fileio.h"
 #include "audit.h"
 #include "bus-message.h"
-#include "bus-util.h"
 #include "strv.h"
 #include "bus-creds.h"
 #include "bus-label.h"
+#include "bus-internal.h"
 
 enum {
         CAP_OFFSET_INHERITABLE = 0,
diff --git a/src/libsystemd/sd-bus/bus-internal.c b/src/libsystemd/sd-bus/bus-internal.c
index fea796cd30..f4ab57f5bc 100644
--- a/src/libsystemd/sd-bus/bus-internal.c
+++ b/src/libsystemd/sd-bus/bus-internal.c
@@ -371,3 +371,45 @@ int bus_maybe_reply_error(sd_bus_message *m, int r, sd_bus_error *error) {
 
         return 1;
 }
+
+bool is_kdbus_wanted(void) {
+        _cleanup_free_ char *value = NULL;
+#ifdef ENABLE_KDBUS
+        const bool configured = true;
+#else
+        const bool configured = false;
+#endif
+        int r;
+
+        if (get_proc_cmdline_key("kdbus", NULL) > 0)
+                return true;
+
+        r = get_proc_cmdline_key("kdbus=", &value);
+        if (r <= 0)
+                return configured;
+
+        return parse_boolean(value) == 1;
+}
+
+bool is_kdbus_available(void) {
+        static int cached = -1;
+        _cleanup_close_ int fd = -1;
+        struct kdbus_cmd cmd = { .size = sizeof(cmd), .flags = KDBUS_FLAG_NEGOTIATE };
+
+        if (cached >= 0)
+                return (bool) cached;
+
+        if (!is_kdbus_wanted()) {
+                cached = false;
+                return false;
+        }
+
+        fd = open("/sys/fs/kdbus/control", O_RDWR | O_CLOEXEC | O_NONBLOCK | O_NOCTTY);
+        if (fd < 0) {
+                cached = false;
+                return false;
+        }
+
+        cached = ioctl(fd, KDBUS_CMD_BUS_MAKE, &cmd) >= 0;
+        return cached;
+}
diff --git a/src/libsystemd/sd-bus/bus-internal.h b/src/libsystemd/sd-bus/bus-internal.h
index c3e20ee1bf..d420a7594f 100644
--- a/src/libsystemd/sd-bus/bus-internal.h
+++ b/src/libsystemd/sd-bus/bus-internal.h
@@ -37,6 +37,29 @@
 #include "bus-kernel.h"
 #include "kdbus.h"
 
+typedef enum BusTransport {
+        BUS_TRANSPORT_LOCAL,
+        BUS_TRANSPORT_REMOTE,
+        BUS_TRANSPORT_MACHINE,
+        _BUS_TRANSPORT_MAX,
+        _BUS_TRANSPORT_INVALID = -1
+} BusTransport;
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_bus*, sd_bus_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_bus*, sd_bus_flush_close_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_bus_slot*, sd_bus_slot_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_bus_message*, sd_bus_message_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_bus_creds*, sd_bus_creds_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_bus_track*, sd_bus_track_unref);
+
+#define _cleanup_bus_unref_ _cleanup_(sd_bus_unrefp)
+#define _cleanup_bus_flush_close_unref_ _cleanup_(sd_bus_flush_close_unrefp)
+#define _cleanup_bus_slot_unref_ _cleanup_(sd_bus_slot_unrefp)
+#define _cleanup_bus_message_unref_ _cleanup_(sd_bus_message_unrefp)
+#define _cleanup_bus_creds_unref_ _cleanup_(sd_bus_creds_unrefp)
+#define _cleanup_bus_track_unref_ _cleanup_(sd_bus_slot_unrefp)
+#define _cleanup_bus_error_free_ _cleanup_(sd_bus_error_free)
+
 struct reply_callback {
         sd_bus_message_handler_t callback;
         usec_t timeout;
@@ -393,3 +416,6 @@ int bus_remove_match_by_string(sd_bus *bus, const char *match, sd_bus_message_ha
 int bus_get_root_path(sd_bus *bus);
 
 int bus_maybe_reply_error(sd_bus_message *m, int r, sd_bus_error *error);
+
+bool is_kdbus_wanted(void);
+bool is_kdbus_available(void);
diff --git a/src/libsystemd/sd-bus/bus-kernel.c b/src/libsystemd/sd-bus/bus-kernel.c
index 22a43c4542..21f3700128 100644
--- a/src/libsystemd/sd-bus/bus-kernel.c
+++ b/src/libsystemd/sd-bus/bus-kernel.c
@@ -45,7 +45,6 @@
 #include "bus-message.h"
 #include "bus-kernel.h"
 #include "bus-bloom.h"
-#include "bus-util.h"
 #include "bus-label.h"
 
 #define UNIQUE_NAME_MAX (3+DECIMAL_STR_MAX(uint64_t))
diff --git a/src/libsystemd/sd-bus/bus-match.c b/src/libsystemd/sd-bus/bus-match.c
index 18c36ce243..f3b49c0c90 100644
--- a/src/libsystemd/sd-bus/bus-match.c
+++ b/src/libsystemd/sd-bus/bus-match.c
@@ -22,7 +22,6 @@
 #include "bus-internal.h"
 #include "bus-message.h"
 #include "bus-match.h"
-#include "bus-util.h"
 #include "strv.h"
 
 /* Example:
diff --git a/src/libsystemd/sd-bus/bus-message.c b/src/libsystemd/sd-bus/bus-message.c
index 94427ed664..b0577cc412 100644
--- a/src/libsystemd/sd-bus/bus-message.c
+++ b/src/libsystemd/sd-bus/bus-message.c
@@ -35,7 +35,6 @@
 #include "bus-type.h"
 #include "bus-signature.h"
 #include "bus-gvariant.h"
-#include "bus-util.h"
 
 static int message_append_basic(sd_bus_message *m, char type, const void *p, const void **stored);
 
diff --git a/src/libsystemd/sd-bus/bus-objects.c b/src/libsystemd/sd-bus/bus-objects.c
index c25293e5e9..17ce297510 100644
--- a/src/libsystemd/sd-bus/bus-objects.c
+++ b/src/libsystemd/sd-bus/bus-objects.c
@@ -26,7 +26,6 @@
 #include "bus-type.h"
 #include "bus-signature.h"
 #include "bus-introspect.h"
-#include "bus-util.h"
 #include "bus-slot.h"
 #include "bus-objects.h"
 
diff --git a/src/libsystemd/sd-bus/bus-track.c b/src/libsystemd/sd-bus/bus-track.c
index e43891be25..7803e39c3d 100644
--- a/src/libsystemd/sd-bus/bus-track.c
+++ b/src/libsystemd/sd-bus/bus-track.c
@@ -20,7 +20,6 @@
 ***/
 
 #include "sd-bus.h"
-#include "bus-util.h"
 #include "bus-internal.h"
 #include "bus-track.h"
 
diff --git a/src/libsystemd/sd-bus/busctl.c b/src/libsystemd/sd-bus/busctl.c
index a1f0f30d6c..181621ffc7 100644
--- a/src/libsystemd/sd-bus/busctl.c
+++ b/src/libsystemd/sd-bus/busctl.c
@@ -30,7 +30,6 @@
 #include "set.h"
 
 #include "sd-bus.h"
-#include "bus-internal.h"
 #include "bus-util.h"
 #include "bus-dump.h"
 #include "bus-signature.h"
diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c
index 0f075907d5..763f830e2d 100644
--- a/src/libsystemd/sd-bus/sd-bus.c
+++ b/src/libsystemd/sd-bus/sd-bus.c
@@ -43,7 +43,6 @@
 #include "bus-kernel.h"
 #include "bus-control.h"
 #include "bus-objects.h"
-#include "bus-util.h"
 #include "bus-container.h"
 #include "bus-protocol.h"
 #include "bus-track.h"
@@ -1173,7 +1172,10 @@ int bus_set_address_system(sd_bus *b) {
         if (e)
                 return sd_bus_set_address(b, e);
 
-        return sd_bus_set_address(b, DEFAULT_SYSTEM_BUS_ADDRESS);
+        if (is_kdbus_available())
+                return sd_bus_set_address(b, KERNEL_SYSTEM_BUS_ADDRESS);
+
+        return sd_bus_set_address(b, UNIX_SYSTEM_BUS_ADDRESS);
 }
 
 _public_ int sd_bus_open_system(sd_bus **ret) {
@@ -1221,16 +1223,17 @@ int bus_set_address_user(sd_bus *b) {
                 return sd_bus_set_address(b, e);
 
         e = secure_getenv("XDG_RUNTIME_DIR");
-        if (e) {
+        if (is_kdbus_available())
+                (void) asprintf(&b->address, KERNEL_USER_BUS_ADDRESS_FMT, getuid());
+        else if (e) {
                 _cleanup_free_ char *ee = NULL;
 
                 ee = bus_address_escape(e);
                 if (!ee)
                         return -ENOMEM;
 
-                (void) asprintf(&b->address, KERNEL_USER_BUS_ADDRESS_FMT ";" UNIX_USER_BUS_ADDRESS_FMT, getuid(), ee);
-        } else
-                (void) asprintf(&b->address, KERNEL_USER_BUS_ADDRESS_FMT, getuid());
+                (void) asprintf(&b->address, UNIX_USER_BUS_ADDRESS_FMT, ee);
+        }
 
         if (!b->address)
                 return -ENOMEM;
diff --git a/src/libsystemd/sd-bus/test-bus-benchmark.c b/src/libsystemd/sd-bus/test-bus-benchmark.c
index d14110aa04..d3bf6da850 100644
--- a/src/libsystemd/sd-bus/test-bus-benchmark.c
+++ b/src/libsystemd/sd-bus/test-bus-benchmark.c
@@ -28,7 +28,6 @@
 #include "sd-bus.h"
 #include "bus-kernel.h"
 #include "bus-internal.h"
-#include "bus-util.h"
 
 #define MAX_SIZE (2*1024*1024)
 
diff --git a/src/libsystemd/sd-bus/test-bus-chat.c b/src/libsystemd/sd-bus/test-bus-chat.c
index 754335b5e7..b97729caf7 100644
--- a/src/libsystemd/sd-bus/test-bus-chat.c
+++ b/src/libsystemd/sd-bus/test-bus-chat.c
@@ -33,7 +33,6 @@
 #include "bus-error.h"
 #include "bus-match.h"
 #include "bus-internal.h"
-#include "bus-util.h"
 
 static int match_callback(sd_bus_message *m, void *userdata, sd_bus_error *ret_error) {
         log_info("Match triggered! interface=%s member=%s", strna(sd_bus_message_get_interface(m)), strna(sd_bus_message_get_member(m)));
diff --git a/src/libsystemd/sd-bus/test-bus-cleanup.c b/src/libsystemd/sd-bus/test-bus-cleanup.c
index f586880593..b483d47468 100644
--- a/src/libsystemd/sd-bus/test-bus-cleanup.c
+++ b/src/libsystemd/sd-bus/test-bus-cleanup.c
@@ -22,7 +22,6 @@
 #include <stdio.h>
 
 #include "sd-bus.h"
-#include "bus-util.h"
 #include "bus-internal.h"
 #include "bus-message.h"
 #include "refcnt.h"
diff --git a/src/libsystemd/sd-bus/test-bus-error.c b/src/libsystemd/sd-bus/test-bus-error.c
index 5753c04b0e..f2cfbc706f 100644
--- a/src/libsystemd/sd-bus/test-bus-error.c
+++ b/src/libsystemd/sd-bus/test-bus-error.c
@@ -20,7 +20,6 @@
 ***/
 
 #include "sd-bus.h"
-#include "bus-error.h"
 #include "bus-util.h"
 #include "errno-list.h"
 #include "bus-common-errors.h"
diff --git a/src/libsystemd/sd-bus/test-bus-gvariant.c b/src/libsystemd/sd-bus/test-bus-gvariant.c
index b078bdc5f6..414d4e9a58 100644
--- a/src/libsystemd/sd-bus/test-bus-gvariant.c
+++ b/src/libsystemd/sd-bus/test-bus-gvariant.c
@@ -27,7 +27,6 @@
 #include "macro.h"
 #include "sd-bus.h"
 #include "bus-gvariant.h"
-#include "bus-util.h"
 #include "bus-internal.h"
 #include "bus-message.h"
 #include "bus-dump.h"
diff --git a/src/libsystemd/sd-bus/test-bus-kernel.c b/src/libsystemd/sd-bus/test-bus-kernel.c
index 6506eaab2e..6284153a58 100644
--- a/src/libsystemd/sd-bus/test-bus-kernel.c
+++ b/src/libsystemd/sd-bus/test-bus-kernel.c
@@ -25,8 +25,8 @@
 #include "log.h"
 
 #include "sd-bus.h"
-#include "bus-kernel.h"
 #include "bus-util.h"
+#include "bus-kernel.h"
 #include "bus-dump.h"
 
 int main(int argc, char *argv[]) {
diff --git a/src/libsystemd/sd-bus/test-bus-match.c b/src/libsystemd/sd-bus/test-bus-match.c
index 83cb5c62c2..f659ba3124 100644
--- a/src/libsystemd/sd-bus/test-bus-match.c
+++ b/src/libsystemd/sd-bus/test-bus-match.c
@@ -24,7 +24,6 @@
 
 #include "bus-match.h"
 #include "bus-message.h"
-#include "bus-util.h"
 #include "bus-slot.h"
 
 static bool mask[32];
diff --git a/src/libsystemd/sd-bus/test-bus-objects.c b/src/libsystemd/sd-bus/test-bus-objects.c
index 359984c7f3..1457759d0e 100644
--- a/src/libsystemd/sd-bus/test-bus-objects.c
+++ b/src/libsystemd/sd-bus/test-bus-objects.c
@@ -30,7 +30,6 @@
 #include "sd-bus.h"
 #include "bus-internal.h"
 #include "bus-message.h"
-#include "bus-util.h"
 #include "bus-dump.h"
 
 struct context {
diff --git a/src/libsystemd/sd-bus/test-bus-server.c b/src/libsystemd/sd-bus/test-bus-server.c
index 080d8eddb7..604df098cc 100644
--- a/src/libsystemd/sd-bus/test-bus-server.c
+++ b/src/libsystemd/sd-bus/test-bus-server.c
@@ -28,7 +28,6 @@
 
 #include "sd-bus.h"
 #include "bus-internal.h"
-#include "bus-util.h"
 
 struct context {
         int fds[2];