busctl: add new "introspect" verb for introspecting objects

4 files changed, 565 insertions, 70 deletions

diff --git a/man/busctl.xml b/man/busctl.xml
index 730a3344d6..ccbd832a75 100644
--- a/man/busctl.xml
+++ b/man/busctl.xml
@@ -186,13 +186,10 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
       </varlistentry>
 
       <varlistentry>
-        <term><command>tree</command> <arg choice="opt" rep="repeat"><replaceable>SERVICE</replaceable></arg></term>
+        <term><command>status</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg></term>
 
-        <listitem><para>Shows an object tree of one or more
-        services. If <replaceable>SERVICE</replaceable> is specified,
-        show object tree of the specified services only. Otherwise,
-        show all object trees of all services on the bus that acquired
-        at least one well-known name.</para></listitem>
+        <listitem><para>Show process information and credentials of a
+        bus service.</para></listitem>
       </varlistentry>
 
       <varlistentry>
@@ -201,7 +198,7 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
         <listitem><para>Dump messages being exchanged. If
         <replaceable>SERVICE</replaceable> is specified, show messages
         to or from this endpoint. Otherwise, show all messages on the
-        bus.</para></listitem>
+        bus. Use Ctrl-C to terminate dump.</para></listitem>
       </varlistentry>
 
       <varlistentry>
@@ -218,24 +215,35 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
       </varlistentry>
 
       <varlistentry>
-        <term><command>status</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg></term>
+        <term><command>tree</command> <arg choice="opt" rep="repeat"><replaceable>SERVICE</replaceable></arg></term>
 
-        <listitem><para>Show process information and credentials of a
-        bus service.</para></listitem>
+        <listitem><para>Shows an object tree of one or more
+        services. If <replaceable>SERVICE</replaceable> is specified,
+        show object tree of the specified services only. Otherwise,
+        show all object trees of all services on the bus that acquired
+        at least one well-known name.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><command>introspect</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg></term>
+
+        <listitem><para>Show interfaces, methods, properties and
+        signals of the specified object (identified by its path) on
+        the specified service.</para></listitem>
       </varlistentry>
 
       <varlistentry>
-        <term><command>call</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="plain"><replaceable>INTERFACE</replaceable></arg> <arg choice="plain"><replaceable>METHOD</replaceable></arg> <arg choice="opt"><replaceable>SIGNATURE</replaceable> <arg choice="opt" rep="repeat"><replaceable>PARAMETERS</replaceable></arg></arg></term>
+        <term><command>call</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="plain"><replaceable>INTERFACE</replaceable></arg> <arg choice="plain"><replaceable>METHOD</replaceable></arg> <arg choice="opt"><replaceable>SIGNATURE</replaceable> <arg choice="opt" rep="repeat"><replaceable>ARGUMENT</replaceable></arg></arg></term>
 
         <listitem><para>Invoke a method and show the response. Takes a
         service name, object path, interface name and method name. If
         parameters shall be passed to the method call a signature
-        string is required, followed by the individual parameters,
-        individually formatted as textual arguments.</para></listitem>
+        string is required, followed by the individual arguments,
+        individually formatted as textual parameters.</para></listitem>
       </varlistentry>
 
       <varlistentry>
-        <term><command>get-property</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="opt"><replaceable>INTERFACE</replaceable> <arg choice="opt" rep="repeat"><replaceable>PROPERTIES</replaceable></arg></arg></term>
+        <term><command>get-property</command> <arg choice="plain"><replaceable>SERVICE</replaceable></arg> <arg choice="plain"><replaceable>OBJECT</replaceable></arg> <arg choice="opt"><replaceable>INTERFACE</replaceable> <arg choice="opt" rep="repeat"><replaceable>PROPERTY</replaceable></arg></arg></term>
 
         <listitem><para>Retrieve the current value one or more object
         properties. Takes a service name and object path. Optionally
diff --git a/src/libsystemd/sd-bus/busctl-introspect.c b/src/libsystemd/sd-bus/busctl-introspect.c
index 041702864b..15c10da7e9 100644
--- a/src/libsystemd/sd-bus/busctl-introspect.c
+++ b/src/libsystemd/sd-bus/busctl-introspect.c
@@ -38,11 +38,30 @@ typedef struct Context {
         char *member_signature;
         char *member_result;
         uint64_t member_flags;
+        bool member_writable;
 
         const char *current;
         void *xml_state;
 } Context;
 
+static void context_reset_member(Context *c) {
+        free(c->member_name);
+        free(c->member_signature);
+        free(c->member_result);
+
+        c->member_name = c->member_signature = c->member_result = NULL;
+        c->member_flags = 0;
+        c->member_writable = false;
+}
+
+static void context_reset_interface(Context *c) {
+        free(c->interface_name);
+        c->interface_name = NULL;
+        c->interface_flags = 0;
+
+        context_reset_member(c);
+}
+
 static int parse_xml_annotation(Context *context, uint64_t *flags) {
 
         enum {
@@ -105,11 +124,11 @@ static int parse_xml_annotation(Context *context, uint64_t *flags) {
                                         } else if (streq_ptr(field, "org.freedesktop.DBus.Property.EmitsChangedSignal")) {
 
                                                 if (streq_ptr(value, "const"))
-                                                        *flags |= SD_BUS_VTABLE_PROPERTY_CONST;
+                                                        *flags = (*flags & ~(SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION|SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE)) | SD_BUS_VTABLE_PROPERTY_CONST;
                                                 else if (streq_ptr(value, "invalidates"))
-                                                        *flags |= SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION;
+                                                        *flags = (*flags & ~(SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE|SD_BUS_VTABLE_PROPERTY_CONST)) | SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION;
                                                 else if (streq_ptr(value, "false"))
-                                                        *flags |= SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE;
+                                                        *flags = *flags & ~(SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE|SD_BUS_VTABLE_PROPERTY_CONST|SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION);
                                         }
                                 }
 
@@ -182,7 +201,7 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
                 STATE_PROPERTY_ACCESS,
         } state = STATE_NODE;
 
-        _cleanup_free_ char *node_path = NULL;
+        _cleanup_free_ char *node_path = NULL, *argument_type = NULL, *argument_direction = NULL;
         const char *np = prefix;
         int r;
 
@@ -225,7 +244,6 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                                 if (streq_ptr(name, "interface"))
                                         state = STATE_INTERFACE;
-
                                 else if (streq_ptr(name, "node")) {
 
                                         r = parse_xml_node(context, np, n_depth+1);
@@ -297,9 +315,10 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
                                         state = STATE_METHOD;
                                 else if (streq_ptr(name, "signal"))
                                         state = STATE_SIGNAL;
-                                else if (streq_ptr(name, "property"))
+                                else if (streq_ptr(name, "property")) {
+                                        context->member_flags |= SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE;
                                         state = STATE_PROPERTY;
-                                else if (streq_ptr(name, "annotation")) {
+                                } else if (streq_ptr(name, "annotation")) {
                                         r = parse_xml_annotation(context, &context->interface_flags);
                                         if (r < 0)
                                                 return r;
@@ -308,11 +327,21 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
                                         return -EINVAL;
                                 }
                         } else if (t == XML_TAG_CLOSE_EMPTY ||
-                                   (t == XML_TAG_CLOSE && streq_ptr(name, "interface")))
+                                   (t == XML_TAG_CLOSE && streq_ptr(name, "interface"))) {
+
+                                if (n_depth == 0) {
+                                        if (context->ops->on_interface) {
+                                                r = context->ops->on_interface(context->interface_name, context->interface_flags, context->userdata);
+                                                if (r < 0)
+                                                        return r;
+                                        }
+
+                                        context_reset_interface(context);
+                                }
 
                                 state = STATE_NODE;
 
-                        else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
+                        } else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
                                 log_error("Unexpected token in <interface>. (1)");
                                 return -EINVAL;
                         }
@@ -321,9 +350,15 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_INTERFACE_NAME:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+                                if (n_depth == 0) {
+                                        free(context->interface_name);
+                                        context->interface_name = name;
+                                        name = NULL;
+                                }
+
                                 state = STATE_INTERFACE;
-                        else {
+                        } else {
                                 log_error("Unexpected token in <interface>. (2)");
                                 return -EINVAL;
                         }
@@ -351,11 +386,21 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
                                         return -EINVAL;
                                 }
                         } else if (t == XML_TAG_CLOSE_EMPTY ||
-                                   (t == XML_TAG_CLOSE && streq_ptr(name, "method")))
+                                   (t == XML_TAG_CLOSE && streq_ptr(name, "method"))) {
+
+                                if (n_depth == 0) {
+                                        if (context->ops->on_method) {
+                                                r = context->ops->on_method(context->interface_name, context->member_name, context->member_signature, context->member_result, context->member_flags, context->userdata);
+                                                if (r < 0)
+                                                        return r;
+                                        }
+
+                                        context_reset_member(context);
+                                }
 
                                 state = STATE_INTERFACE;
 
-                        else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
+                        } else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
                                 log_error("Unexpected token in <method> (1).");
                                 return -EINVAL;
                         }
@@ -364,9 +409,16 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_METHOD_NAME:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+
+                                if (n_depth == 0) {
+                                        free(context->member_name);
+                                        context->member_name = name;
+                                        name = NULL;
+                                }
+
                                 state = STATE_METHOD;
-                        else {
+                        } else {
                                 log_error("Unexpected token in <method> (2).");
                                 return -EINVAL;
                         }
@@ -396,11 +448,27 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
                                         return -EINVAL;
                                 }
                         } else if (t == XML_TAG_CLOSE_EMPTY ||
-                                   (t == XML_TAG_CLOSE && streq_ptr(name, "arg")))
+                                   (t == XML_TAG_CLOSE && streq_ptr(name, "arg"))) {
+
+                                if (n_depth == 0) {
+
+                                        if (argument_type) {
+                                                if (!argument_direction || streq(argument_direction, "in")) {
+                                                        if (!strextend(&context->member_signature, argument_type, NULL))
+                                                                return log_oom();
+                                                } else if (streq(argument_direction, "out")) {
+                                                        if (!strextend(&context->member_result, argument_type, NULL))
+                                                                return log_oom();
+                                                }
+                                        }
 
-                                state = STATE_METHOD;
+                                        free(argument_type);
+                                        free(argument_direction);
+                                        argument_type = argument_direction = NULL;
+                                }
 
-                        else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
+                                state = STATE_METHOD;
+                        } else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
                                 log_error("Unexpected token in method <arg>. (1)");
                                 return -EINVAL;
                         }
@@ -420,9 +488,13 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_METHOD_ARG_TYPE:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+                                free(argument_type);
+                                argument_type = name;
+                                name = NULL;
+
                                 state = STATE_METHOD_ARG;
-                        else {
+                        } else {
                                 log_error("Unexpected token in method <arg>. (3)");
                                 return -EINVAL;
                         }
@@ -431,9 +503,13 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_METHOD_ARG_DIRECTION:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+                                free(argument_direction);
+                                argument_direction = name;
+                                name = NULL;
+
                                 state = STATE_METHOD_ARG;
-                        else {
+                        } else {
                                 log_error("Unexpected token in method <arg>. (4)");
                                 return -EINVAL;
                         }
@@ -461,11 +537,21 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
                                         return -EINVAL;
                                 }
                         } else if (t == XML_TAG_CLOSE_EMPTY ||
-                                   (t == XML_TAG_CLOSE && streq_ptr(name, "signal")))
+                                   (t == XML_TAG_CLOSE && streq_ptr(name, "signal"))) {
+
+                                if (n_depth == 0) {
+                                        if (context->ops->on_signal) {
+                                                r = context->ops->on_signal(context->interface_name, context->member_name, context->member_signature, context->member_flags, context->userdata);
+                                                if (r < 0)
+                                                        return r;
+                                        }
+
+                                        context_reset_member(context);
+                                }
 
                                 state = STATE_INTERFACE;
 
-                        else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
+                        } else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
                                 log_error("Unexpected token in <signal>. (1)");
                                 return -EINVAL;
                         }
@@ -474,9 +560,16 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_SIGNAL_NAME:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+
+                                if (n_depth == 0) {
+                                        free(context->member_name);
+                                        context->member_name = name;
+                                        name = NULL;
+                                }
+
                                 state = STATE_SIGNAL;
-                        else {
+                        } else {
                                 log_error("Unexpected token in <signal>. (2)");
                                 return -EINVAL;
                         }
@@ -505,11 +598,18 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
                                         return -EINVAL;
                                 }
                         } else if (t == XML_TAG_CLOSE_EMPTY ||
-                                   (t == XML_TAG_CLOSE && streq_ptr(name, "arg")))
+                                   (t == XML_TAG_CLOSE && streq_ptr(name, "arg"))) {
 
-                                state = STATE_SIGNAL;
+                                if (argument_type) {
+                                        if (!strextend(&context->member_signature, argument_type, NULL))
+                                                return log_oom();
 
-                        else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
+                                        free(argument_type);
+                                        argument_type = NULL;
+                                }
+
+                                state = STATE_SIGNAL;
+                        } else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
                                 log_error("Unexpected token in signal <arg> (1).");
                                 return -EINVAL;
                         }
@@ -529,9 +629,13 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_SIGNAL_ARG_TYPE:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+                                free(argument_type);
+                                argument_type = name;
+                                name = NULL;
+
                                 state = STATE_SIGNAL_ARG;
-                        else {
+                        } else {
                                 log_error("Unexpected token in signal <arg> (3).");
                                 return -EINVAL;
                         }
@@ -563,11 +667,21 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
                                 }
 
                         } else if (t == XML_TAG_CLOSE_EMPTY ||
-                                   (t == XML_TAG_CLOSE && streq_ptr(name, "property")))
+                                   (t == XML_TAG_CLOSE && streq_ptr(name, "property"))) {
+
+                                if (n_depth == 0) {
+                                        if (context->ops->on_property) {
+                                                r = context->ops->on_property(context->interface_name, context->member_name, context->member_signature, context->member_writable, context->member_flags, context->userdata);
+                                                if (r < 0)
+                                                        return r;
+                                        }
+
+                                        context_reset_member(context);
+                                }
 
                                 state = STATE_INTERFACE;
 
-                        else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
+                        } else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
                                 log_error("Unexpected token in <property>. (1)");
                                 return -EINVAL;
                         }
@@ -576,9 +690,15 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_PROPERTY_NAME:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+
+                                if (n_depth == 0) {
+                                        free(context->member_name);
+                                        context->member_name = name;
+                                        name = NULL;
+                                }
                                 state = STATE_PROPERTY;
-                        else {
+                        } else {
                                 log_error("Unexpected token in <property>. (2)");
                                 return -EINVAL;
                         }
@@ -587,9 +707,16 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_PROPERTY_TYPE:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+
+                                if (n_depth == 0) {
+                                        free(context->member_signature);
+                                        context->member_signature = name;
+                                        name = NULL;
+                                }
+
                                 state = STATE_PROPERTY;
-                        else {
+                        } else {
                                 log_error("Unexpected token in <property>. (3)");
                                 return -EINVAL;
                         }
@@ -598,9 +725,13 @@ static int parse_xml_node(Context *context, const char *prefix, unsigned n_depth
 
                 case STATE_PROPERTY_ACCESS:
 
-                        if (t == XML_ATTRIBUTE_VALUE)
+                        if (t == XML_ATTRIBUTE_VALUE) {
+
+                                if (streq(name, "readwrite") || streq(name, "write"))
+                                        context->member_writable = true;
+
                                 state = STATE_PROPERTY;
-                        else {
+                        } else {
                                 log_error("Unexpected token in <property>. (4)");
                                 return -EINVAL;
                         }
@@ -629,27 +760,34 @@ int parse_xml_introspect(const char *prefix, const char *xml, const XMLIntrospec
                 r = xml_tokenize(&context.current, &name, &context.xml_state, NULL);
                 if (r < 0) {
                         log_error("XML parse error");
-                        return r;
+                        goto finish;
                 }
 
-                if (r == XML_END)
+                if (r == XML_END) {
+                        r = 0;
                         break;
+                }
 
                 if (r == XML_TAG_OPEN) {
 
                         if (streq(name, "node")) {
                                 r = parse_xml_node(&context, prefix, 0);
                                 if (r < 0)
-                                        return r;
+                                        goto finish;
                         } else {
                                 log_error("Unexpected tag '%s' in introspection data.", name);
-                                return -EBADMSG;
+                                r = -EBADMSG;
+                                goto finish;
                         }
                 } else if (r != XML_TEXT || !in_charset(name, WHITESPACE)) {
                         log_error("Unexpected token.");
-                        return -EINVAL;
+                        r = -EBADMSG;
+                        goto finish;
                 }
         }
 
-        return 0;
+finish:
+        context_reset_interface(&context);
+
+        return r;
 }
diff --git a/src/libsystemd/sd-bus/busctl-introspect.h b/src/libsystemd/sd-bus/busctl-introspect.h
index 7c4cd6e5fd..9bea43717d 100644
--- a/src/libsystemd/sd-bus/busctl-introspect.h
+++ b/src/libsystemd/sd-bus/busctl-introspect.h
@@ -25,11 +25,10 @@
 
 typedef struct XMLIntrospectOps {
         int (*on_path)(const char *path, void *userdata);
-        int (*on_interface)(const char *name, uint64_t flags);
-        int (*on_method)(const char *name, const char *signature, const char *result, uint64_t flags, void *userdata);
-        int (*on_signal)(const char *name, const char *signature, uint64_t flags, void *userdata);
-        int (*on_property)(const char *name, const char *signature, uint64_t flags);
-        int (*on_writable_property)(const char *name, const char *signature, uint64_t flags);
+        int (*on_interface)(const char *name, uint64_t flags, void *userdata);
+        int (*on_method)(const char *interface, const char *name, const char *signature, const char *result, uint64_t flags, void *userdata);
+        int (*on_signal)(const char *interface, const char *name, const char *signature, uint64_t flags, void *userdata);
+        int (*on_property)(const char *interface, const char *name, const char *signature, bool writable, uint64_t flags, void *userdata);
 } XMLIntrospectOps;
 
 int parse_xml_introspect(const char *prefix, const char *xml, const XMLIntrospectOps *ops, void *userdata);
diff --git a/src/libsystemd/sd-bus/busctl.c b/src/libsystemd/sd-bus/busctl.c
index c58a97bc14..bb89ab9d3c 100644
--- a/src/libsystemd/sd-bus/busctl.c
+++ b/src/libsystemd/sd-bus/busctl.c
@@ -319,7 +319,7 @@ static int on_path(const char *path, void *userdata) {
 }
 
 static int find_nodes(sd_bus *bus, const char *service, const char *path, Set *paths) {
-        const XMLIntrospectOps ops = {
+        static const XMLIntrospectOps ops = {
                 .on_path = on_path,
         };
 
@@ -338,7 +338,6 @@ static int find_nodes(sd_bus *bus, const char *service, const char *path, Set *p
         if (r < 0)
                 return bus_log_parse_error(r);
 
-        /* fputs(xml, stdout); */
         return parse_xml_introspect(path, xml, &ops, paths);
 }
 
@@ -470,6 +469,353 @@ static int tree(sd_bus *bus, char **argv) {
         return r;
 }
 
+typedef struct Member {
+        const char *type;
+        char *interface;
+        char *name;
+        char *signature;
+        char *result;
+        bool writable;
+        uint64_t flags;
+} Member;
+
+static unsigned long member_hash_func(const void *p, const uint8_t hash_key[]) {
+        const Member *m = p;
+        unsigned long ul;
+
+        assert(m);
+        assert(m->type);
+
+        ul = string_hash_func(m->type, hash_key);
+
+        if (m->name)
+                ul ^= string_hash_func(m->name, hash_key);
+
+        if (m->interface)
+                ul ^= string_hash_func(m->interface, hash_key);
+
+        return ul;
+}
+
+static int member_compare_func(const void *a, const void *b) {
+        const Member *x = a, *y = b;
+        int d;
+
+        assert(x);
+        assert(y);
+        assert(x->type);
+        assert(y->type);
+
+        if (!x->interface && y->interface)
+                return -1;
+        if (x->interface && !y->interface)
+                return 1;
+        if (x->interface && y->interface) {
+                d = strcmp(x->interface, y->interface);
+                if (d != 0)
+                        return d;
+        }
+
+        d = strcmp(x->type, y->type);
+        if (d != 0)
+                return d;
+
+        if (!x->name && y->name)
+                return -1;
+        if (x->name && !y->name)
+                return 1;
+        if (x->name && y->name)
+                return strcmp(x->name, y->name);
+
+        return 0;
+}
+
+static int member_compare_funcp(const void *a, const void *b) {
+        const Member *const * x = (const Member *const *) a, * const *y = (const Member *const *) b;
+
+        return member_compare_func(*x, *y);
+}
+
+static void member_free(Member *m) {
+        if (!m)
+                return;
+
+        free(m->interface);
+        free(m->name);
+        free(m->signature);
+        free(m->result);
+        free(m);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(Member*, member_free);
+
+static void member_set_free(Set *s) {
+        Member *m;
+
+        while ((m = set_steal_first(s)))
+                member_free(m);
+
+        set_free(s);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(Set*, member_set_free);
+
+static int on_interface(const char *interface, uint64_t flags, void *userdata) {
+        _cleanup_(member_freep) Member *m;
+        Set *members = userdata;
+        int r;
+
+        assert(interface);
+        assert(members);
+
+        m = new0(Member, 1);
+        if (!m)
+                return log_oom();
+
+        m->type = "interface";
+        m->flags = flags;
+
+        r = free_and_strdup(&m->interface, interface);
+        if (r < 0)
+                return log_oom();
+
+        r = set_put(members, m);
+        if (r <= 0) {
+                log_error("Duplicate interface");
+                return -EINVAL;
+        }
+
+        m = NULL;
+        return 0;
+}
+
+static int on_method(const char *interface, const char *name, const char *signature, const char *result, uint64_t flags, void *userdata) {
+        _cleanup_(member_freep) Member *m;
+        Set *members = userdata;
+        int r;
+
+        assert(interface);
+        assert(name);
+
+        m = new0(Member, 1);
+        if (!m)
+                return log_oom();
+
+        m->type = "method";
+        m->flags = flags;
+
+        r = free_and_strdup(&m->interface, interface);
+        if (r < 0)
+                return log_oom();
+
+        r = free_and_strdup(&m->name, name);
+        if (r < 0)
+                return log_oom();
+
+        r = free_and_strdup(&m->signature, signature);
+        if (r < 0)
+                return log_oom();
+
+        r = free_and_strdup(&m->result, result);
+        if (r < 0)
+                return log_oom();
+
+        r = set_put(members, m);
+        if (r <= 0) {
+                log_error("Duplicate method");
+                return -EINVAL;
+        }
+
+        m = NULL;
+        return 0;
+}
+
+static int on_signal(const char *interface, const char *name, const char *signature, uint64_t flags, void *userdata) {
+        _cleanup_(member_freep) Member *m;
+        Set *members = userdata;
+        int r;
+
+        assert(interface);
+        assert(name);
+
+        m = new0(Member, 1);
+        if (!m)
+                return log_oom();
+
+        m->type = "signal";
+        m->flags = flags;
+
+        r = free_and_strdup(&m->interface, interface);
+        if (r < 0)
+                return log_oom();
+
+        r = free_and_strdup(&m->name, name);
+        if (r < 0)
+                return log_oom();
+
+        r = free_and_strdup(&m->signature, signature);
+        if (r < 0)
+                return log_oom();
+
+        r = set_put(members, m);
+        if (r <= 0) {
+                log_error("Duplicate signal");
+                return -EINVAL;
+        }
+
+        m = NULL;
+        return 0;
+}
+
+static int on_property(const char *interface, const char *name, const char *signature, bool writable, uint64_t flags, void *userdata) {
+        _cleanup_(member_freep) Member *m;
+        Set *members = userdata;
+        int r;
+
+        assert(interface);
+        assert(name);
+
+        m = new0(Member, 1);
+        if (!m)
+                return log_oom();
+
+        m->type = "property";
+        m->flags = flags;
+        m->writable = writable;
+
+        r = free_and_strdup(&m->interface, interface);
+        if (r < 0)
+                return log_oom();
+
+        r = free_and_strdup(&m->name, name);
+        if (r < 0)
+                return log_oom();
+
+        r = free_and_strdup(&m->signature, signature);
+        if (r < 0)
+                return log_oom();
+
+        r = set_put(members, m);
+        if (r <= 0) {
+                log_error("Duplicate property");
+                return -EINVAL;
+        }
+
+        m = NULL;
+        return 0;
+}
+
+static const char *strdash(const char *x) {
+        return isempty(x) ? "-" : x;
+}
+
+static int introspect(sd_bus *bus, char **argv) {
+        static const struct hash_ops member_hash_ops = {
+                .hash = member_hash_func,
+                .compare = member_compare_func,
+        };
+
+        static const XMLIntrospectOps ops = {
+                .on_interface = on_interface,
+                .on_method = on_method,
+                .on_signal = on_signal,
+                .on_property = on_property,
+        };
+
+        _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(member_set_freep) Set *members = NULL;
+        Iterator i;
+        Member *m;
+        const char *xml;
+        int r;
+        unsigned name_width,  type_width, signature_width, result_width;
+        Member **sorted = NULL;
+        unsigned k = 0, j;
+
+        if (strv_length(argv) != 3) {
+                log_error("Requires service and object path argument.");
+                return -EINVAL;
+        }
+
+        members = set_new(&member_hash_ops);
+        if (!members)
+                return log_oom();
+
+        r = sd_bus_call_method(bus, argv[1], argv[2], "org.freedesktop.DBus.Introspectable", "Introspect", &error, &reply, "");
+        if (r < 0) {
+                log_error("Failed to introspect object %s of service %s: %s", argv[2], argv[1], bus_error_message(&error, r));
+                return r;
+        }
+
+        r = sd_bus_message_read(reply, "s", &xml);
+        if (r < 0)
+                return bus_log_parse_error(r);
+
+        r = parse_xml_introspect(argv[2], xml, &ops, members);
+        if (r < 0)
+                return r;
+
+        pager_open_if_enabled();
+
+        name_width = strlen("NAME");
+        type_width = strlen("TYPE");
+        signature_width = strlen("SIGNATURE");
+        result_width = strlen("RESULT");
+
+        sorted = newa(Member*, set_size(members));
+
+        SET_FOREACH(m, members, i) {
+                if (m->interface)
+                        name_width = MAX(name_width, strlen(m->interface));
+                if (m->name)
+                        name_width = MAX(name_width, strlen(m->name) + 1);
+                if (m->type)
+                        type_width = MAX(type_width, strlen(m->type));
+                if (m->signature)
+                        signature_width = MAX(signature_width, strlen(m->signature));
+                if (m->result)
+                        result_width = MAX(result_width, strlen(m->result));
+
+                sorted[k++] = m;
+        }
+
+        assert(k == set_size(members));
+        qsort(sorted, k, sizeof(Member*), member_compare_funcp);
+
+        printf("%-*s %-*s %-*s %-*s %s\n",
+               (int) name_width, "NAME",
+               (int) type_width, "TYPE",
+               (int) signature_width, "SIGNATURE",
+               (int) result_width, "RESULT",
+               "FLAGS");
+
+        for (j = 0; j < k; j++) {
+                bool is_interface;
+
+                m = sorted[j];
+
+                is_interface = streq(m->type, "interface");
+
+                printf("%s%s%-*s%s %-*s %-*s %-*s%s%s%s%s%s%s\n",
+                       is_interface ? ansi_highlight() : "",
+                       is_interface ? "" : ".",
+                       - !is_interface + (int) name_width, strdash(streq_ptr(m->type, "interface") ? m->interface : m->name),
+                       is_interface ? ansi_highlight_off() : "",
+                       (int) type_width, strdash(m->type),
+                       (int) signature_width, strdash(m->signature),
+                       (int) result_width, strdash(m->result),
+                       (m->flags & SD_BUS_VTABLE_DEPRECATED) ? " deprecated" : (m->flags || m->writable ? "" : " -"),
+                       (m->flags & SD_BUS_VTABLE_METHOD_NO_REPLY) ? " no-reply" : "",
+                       (m->flags & SD_BUS_VTABLE_PROPERTY_CONST) ? " const" : "",
+                       (m->flags & SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE) ? " emits-change" : "",
+                       (m->flags & SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION) ? " emits-invalidation" : "",
+                       m->writable ? " writable" : "");
+        }
+
+        return 0;
+}
+
 static int message_dump(sd_bus_message *m, FILE *f) {
         return bus_message_dump(m, f, BUS_MESSAGE_DUMP_WITH_HEADER);
 }
@@ -1021,13 +1367,14 @@ static int help(void) {
                "     --quiet              Don't show method call reply\n\n"
                "Commands:\n"
                "  list                    List bus names\n"
-               "  tree [SERVICE...]       Show object tree of service\n"
+               "  status SERVICE          Show service name status\n"
                "  monitor [SERVICE...]    Show bus traffic\n"
                "  capture [SERVICE...]    Capture bus traffic as pcap\n"
-               "  status SERVICE          Show service name status\n"
-               "  call SERVICE PATH INTERFACE METHOD [SIGNATURE [ARGUMENTS...]]\n"
+               "  tree [SERVICE...]       Show object tree of service\n"
+               "  introspect SERVICE PATH\n"
+               "  call SERVICE OBJECT INTERFACE METHOD [SIGNATURE [ARGUMENT...]]\n"
                "                          Call a method\n"
-               "  get-property SERVICE PATH [INTERFACE [PROPERTY...]]\n"
+               "  get-property SERVICE OBJECT [INTERFACE [PROPERTY...]]\n"
                "                          Get property value\n"
                "  help                    Show this help\n"
                , program_invocation_short_name);
@@ -1197,6 +1544,9 @@ static int busctl_main(sd_bus *bus, int argc, char *argv[]) {
         if (streq(argv[optind], "tree"))
                 return tree(bus, argv + optind);
 
+        if (streq(argv[optind], "introspect"))
+                return introspect(bus, argv + optind);
+
         if (streq(argv[optind], "call"))
                 return call(bus, argv + optind);