src/libsystemd/sd-bus/bus-introspect.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include "bus-internal.h"
   4 #include "bus-introspect.h"
   5 #include "bus-objects.h"
   6 #include "bus-protocol.h"
   7 #include "bus-signature.h"
   8 #include "fd-util.h"
   9 #include "fileio.h"
  10 #include "memory-util.h"
  11 #include "string-util.h"
  12
  13 #define BUS_INTROSPECT_DOCTYPE                                       \
  14         "<!DOCTYPE node PUBLIC \"-//freedesktop//DTD D-BUS Object Introspection 1.0//EN\"\n" \
  15         "\"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd\">\n"
  16
  17 #define BUS_INTROSPECT_INTERFACE_PEER                                \
  18         " <interface name=\"org.freedesktop.DBus.Peer\">\n"             \
  19         "  <method name=\"Ping\"/>\n"                                   \
  20         "  <method name=\"GetMachineId\">\n"                            \
  21         "   <arg type=\"s\" name=\"machine_uuid\" direction=\"out\"/>\n" \
  22         "  </method>\n"                                                 \
  23         " </interface>\n"
  24
  25 #define BUS_INTROSPECT_INTERFACE_INTROSPECTABLE                      \
  26         " <interface name=\"org.freedesktop.DBus.Introspectable\">\n"   \
  27         "  <method name=\"Introspect\">\n"                              \
  28         "   <arg name=\"data\" type=\"s\" direction=\"out\"/>\n"        \
  29         "  </method>\n"                                                 \
  30         " </interface>\n"
  31
  32 #define BUS_INTROSPECT_INTERFACE_PROPERTIES                          \
  33         " <interface name=\"org.freedesktop.DBus.Properties\">\n"       \
  34         "  <method name=\"Get\">\n"                                     \
  35         "   <arg name=\"interface\" direction=\"in\" type=\"s\"/>\n"    \
  36         "   <arg name=\"property\" direction=\"in\" type=\"s\"/>\n"     \
  37         "   <arg name=\"value\" direction=\"out\" type=\"v\"/>\n"       \
  38         "  </method>\n"                                                 \
  39         "  <method name=\"GetAll\">\n"                                  \
  40         "   <arg name=\"interface\" direction=\"in\" type=\"s\"/>\n"    \
  41         "   <arg name=\"properties\" direction=\"out\" type=\"a{sv}\"/>\n" \
  42         "  </method>\n"                                                 \
  43         "  <method name=\"Set\">\n"                                     \
  44         "   <arg name=\"interface\" direction=\"in\" type=\"s\"/>\n"    \
  45         "   <arg name=\"property\" direction=\"in\" type=\"s\"/>\n"     \
  46         "   <arg name=\"value\" direction=\"in\" type=\"v\"/>\n"        \
  47         "  </method>\n"                                                 \
  48         "  <signal name=\"PropertiesChanged\">\n"                       \
  49         "   <arg type=\"s\" name=\"interface\"/>\n"                     \
  50         "   <arg type=\"a{sv}\" name=\"changed_properties\"/>\n"        \
  51         "   <arg type=\"as\" name=\"invalidated_properties\"/>\n"       \
  52         "  </signal>\n"                                                 \
  53         " </interface>\n"
  54
  55 #define BUS_INTROSPECT_INTERFACE_OBJECT_MANAGER                      \
  56         " <interface name=\"org.freedesktop.DBus.ObjectManager\">\n"    \
  57         "  <method name=\"GetManagedObjects\">\n"                       \
  58         "   <arg type=\"a{oa{sa{sv}}}\" name=\"object_paths_interfaces_and_properties\" direction=\"out\"/>\n" \
  59         "  </method>\n"                                                 \
  60         "  <signal name=\"InterfacesAdded\">\n"                         \
  61         "   <arg type=\"o\" name=\"object_path\"/>\n"                   \
  62         "   <arg type=\"a{sa{sv}}\" name=\"interfaces_and_properties\"/>\n" \
  63         "  </signal>\n"                                                 \
  64         "  <signal name=\"InterfacesRemoved\">\n"                       \
  65         "   <arg type=\"o\" name=\"object_path\"/>\n"                   \
  66         "   <arg type=\"as\" name=\"interfaces\"/>\n"                   \
  67         "  </signal>\n"                                                 \
  68         " </interface>\n"
  69
  70 int introspect_begin(struct introspect *i, bool trusted) {
  71         assert(i);
  72
  73         *i = (struct introspect) {
  74                 .trusted = trusted,
  75         };
  76
  77         i->f = open_memstream_unlocked(&i->introspection, &i->size);
  78         if (!i->f)
  79                 return -ENOMEM;
  80
  81         fputs(BUS_INTROSPECT_DOCTYPE
  82               "<node>\n", i->f);
  83
  84         return 0;
  85 }
  86
  87 int introspect_write_default_interfaces(struct introspect *i, bool object_manager) {
  88         assert(i);
  89
  90         fputs(BUS_INTROSPECT_INTERFACE_PEER
  91               BUS_INTROSPECT_INTERFACE_INTROSPECTABLE
  92               BUS_INTROSPECT_INTERFACE_PROPERTIES, i->f);
  93
  94         if (object_manager)
  95                 fputs(BUS_INTROSPECT_INTERFACE_OBJECT_MANAGER, i->f);
  96
  97         return 0;
  98 }
  99
 100 static int set_interface_name(struct introspect *intro, const char *interface_name) {
 101         if (streq_ptr(intro->interface_name, interface_name))
 102                 return 0;
 103
 104         if (intro->interface_name)
 105                 fputs(" </interface>\n", intro->f);
 106
 107         if (interface_name)
 108                 fprintf(intro->f, " <interface name=\"%s\">\n", interface_name);
 109
 110         return free_and_strdup(&intro->interface_name, interface_name);
 111 }
 112
 113 int introspect_write_child_nodes(struct introspect *i, Set *s, const char *prefix) {
 114         char *node;
 115
 116         assert(i);
 117         assert(prefix);
 118
 119         assert_se(set_interface_name(i, NULL) >= 0);
 120
 121         while ((node = set_steal_first(s))) {
 122                 const char *e;
 123
 124                 e = object_path_startswith(node, prefix);
 125                 if (e && e[0])
 126                         fprintf(i->f, " <node name=\"%s\"/>\n", e);
 127
 128                 free(node);
 129         }
 130
 131         return 0;
 132 }
 133
 134 static void introspect_write_flags(struct introspect *i, int type, uint64_t flags) {
 135         if (flags & SD_BUS_VTABLE_DEPRECATED)
 136                 fputs("   <annotation name=\"org.freedesktop.DBus.Deprecated\" value=\"true\"/>\n", i->f);
 137
 138         if (type == _SD_BUS_VTABLE_METHOD && (flags & SD_BUS_VTABLE_METHOD_NO_REPLY))
 139                 fputs("   <annotation name=\"org.freedesktop.DBus.Method.NoReply\" value=\"true\"/>\n", i->f);
 140
 141         if (IN_SET(type, _SD_BUS_VTABLE_PROPERTY, _SD_BUS_VTABLE_WRITABLE_PROPERTY)) {
 142                 if (flags & SD_BUS_VTABLE_PROPERTY_EXPLICIT)
 143                         fputs("   <annotation name=\"org.freedesktop.systemd1.Explicit\" value=\"true\"/>\n", i->f);
 144
 145                 if (flags & SD_BUS_VTABLE_PROPERTY_CONST)
 146                         fputs("   <annotation name=\"org.freedesktop.DBus.Property.EmitsChangedSignal\" value=\"const\"/>\n", i->f);
 147                 else if (flags & SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION)
 148                         fputs("   <annotation name=\"org.freedesktop.DBus.Property.EmitsChangedSignal\" value=\"invalidates\"/>\n", i->f);
 149                 else if (!(flags & SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE))
 150                         fputs("   <annotation name=\"org.freedesktop.DBus.Property.EmitsChangedSignal\" value=\"false\"/>\n", i->f);
 151         }
 152
 153         if (!i->trusted &&
 154             IN_SET(type, _SD_BUS_VTABLE_METHOD, _SD_BUS_VTABLE_WRITABLE_PROPERTY) &&
 155             !(flags & SD_BUS_VTABLE_UNPRIVILEGED))
 156                 fputs("   <annotation name=\"org.freedesktop.systemd1.Privileged\" value=\"true\"/>\n", i->f);
 157 }
 158
 159 /* Note that "names" is both an input and an output parameter. It initially points to the first argument name in a
 160    NULL-separated list of strings, and is then advanced with each argument, and the resulting pointer is returned. */
 161 static int introspect_write_arguments(struct introspect *i, const char *signature, const char **names, const char *direction) {
 162         int r;
 163
 164         for (;;) {
 165                 size_t l;
 166
 167                 if (!*signature)
 168                         return 0;
 169
 170                 r = signature_element_length(signature, &l);
 171                 if (r < 0)
 172                         return r;
 173
 174                 fprintf(i->f, "   <arg type=\"%.*s\"", (int) l, signature);
 175
 176                 if (**names != '\0') {
 177                         fprintf(i->f, " name=\"%s\"", *names);
 178                         *names += strlen(*names) + 1;
 179                 }
 180
 181                 if (direction)
 182                         fprintf(i->f, " direction=\"%s\"/>\n", direction);
 183                 else
 184                         fputs("/>\n", i->f);
 185
 186                 signature += l;
 187         }
 188 }
 189
 190 int introspect_write_interface(
 191                 struct introspect *i,
 192                 const char *interface_name,
 193                 const sd_bus_vtable *v) {
 194
 195         const sd_bus_vtable *vtable = v;
 196         const char *names = "";
 197         int r;
 198
 199         assert(i);
 200         assert(interface_name);
 201         assert(v);
 202
 203         r = set_interface_name(i, interface_name);
 204         if (r < 0)
 205                 return r;
 206
 207         for (; v->type != _SD_BUS_VTABLE_END; v = bus_vtable_next(vtable, v)) {
 208
 209                 /* Ignore methods, signals and properties that are
 210                  * marked "hidden", but do show the interface
 211                  * itself */
 212
 213                 if (v->type != _SD_BUS_VTABLE_START && (v->flags & SD_BUS_VTABLE_HIDDEN))
 214                         continue;
 215
 216                 switch (v->type) {
 217
 218                 case _SD_BUS_VTABLE_START:
 219                         if (v->flags & SD_BUS_VTABLE_DEPRECATED)
 220                                 fputs("  <annotation name=\"org.freedesktop.DBus.Deprecated\" value=\"true\"/>\n", i->f);
 221                         break;
 222
 223                 case _SD_BUS_VTABLE_METHOD:
 224                         fprintf(i->f, "  <method name=\"%s\">\n", v->x.method.member);
 225                         if (bus_vtable_has_names(vtable))
 226                                 names = strempty(v->x.method.names);
 227                         introspect_write_arguments(i, strempty(v->x.method.signature), &names, "in");
 228                         introspect_write_arguments(i, strempty(v->x.method.result), &names, "out");
 229                         introspect_write_flags(i, v->type, v->flags);
 230                         fputs("  </method>\n", i->f);
 231                         break;
 232
 233                 case _SD_BUS_VTABLE_PROPERTY:
 234                 case _SD_BUS_VTABLE_WRITABLE_PROPERTY:
 235                         fprintf(i->f, "  <property name=\"%s\" type=\"%s\" access=\"%s\">\n",
 236                                 v->x.property.member,
 237                                 v->x.property.signature,
 238                                 v->type == _SD_BUS_VTABLE_WRITABLE_PROPERTY ? "readwrite" : "read");
 239                         introspect_write_flags(i, v->type, v->flags);
 240                         fputs("  </property>\n", i->f);
 241                         break;
 242
 243                 case _SD_BUS_VTABLE_SIGNAL:
 244                         fprintf(i->f, "  <signal name=\"%s\">\n", v->x.signal.member);
 245                         if (bus_vtable_has_names(vtable))
 246                                 names = strempty(v->x.signal.names);
 247                         introspect_write_arguments(i, strempty(v->x.signal.signature), &names, NULL);
 248                         introspect_write_flags(i, v->type, v->flags);
 249                         fputs("  </signal>\n", i->f);
 250                         break;
 251                 }
 252
 253         }
 254
 255         return 0;
 256 }
 257
 258 int introspect_finish(struct introspect *i, char **ret) {
 259         int r;
 260
 261         assert(i);
 262
 263         assert_se(set_interface_name(i, NULL) >= 0);
 264
 265         fputs("</node>\n", i->f);
 266
 267         r = fflush_and_check(i->f);
 268         if (r < 0)
 269                 return r;
 270
 271         i->f = safe_fclose(i->f);
 272         *ret = TAKE_PTR(i->introspection);
 273
 274         return 0;
 275 }
 276
 277 void introspect_free(struct introspect *i) {
 278         assert(i);
 279
 280         /* Normally introspect_finish() does all the work, this is just a backup for error paths */
 281
 282         safe_fclose(i->f);
 283         free(i->interface_name);
 284         free(i->introspection);
 285 }