src/bin/lttng-sessiond/ust-field-convert.cpp

   1 /*
   2  * Copyright (C) 2022 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #include "ust-field-convert.hpp"
   9
  10 #include <common/make-unique.hpp>
  11
  12 #include <unordered_map>
  13
  14 namespace lst = lttng::sessiond::trace;
  15 namespace lsu = lttng::sessiond::ust;
  16 namespace {
  17
  18 /*
  19  * Type enclosing the session information that may be required during the decoding
  20  * of the lttng_ust_ctl_field array provided by applications on registration of
  21  * an event.
  22  */
  23 class session_attributes {
  24 public:
  25         using registry_enum_getter_fn =
  26                         std::function<lsu::registry_enum::const_rcu_protected_reference(
  27                                         const char *name, uint64_t id)>;
  28
  29         session_attributes(registry_enum_getter_fn reg_enum_getter,
  30                         lst::byte_order native_trace_byte_order) :
  31                 get_registry_enum{reg_enum_getter}, _native_trace_byte_order{native_trace_byte_order}
  32         {
  33         }
  34
  35         const registry_enum_getter_fn get_registry_enum;
  36         const lst::byte_order _native_trace_byte_order;
  37 };
  38
  39 /* Used to publish fields on which a field being decoded has an implicit dependency. */
  40 using publish_field_fn = std::function<void(lst::field::cuptr)>;
  41
  42 lst::type::cuptr create_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
  43                 const lttng_ust_ctl_field *end,
  44                 const session_attributes& session_attributes,
  45                 const lttng_ust_ctl_field **next_ust_ctl_field,
  46                 publish_field_fn publish_field);
  47
  48 void create_field_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
  49                 const lttng_ust_ctl_field *end,
  50                 const session_attributes& session_attributes,
  51                 const lttng_ust_ctl_field **next_ust_ctl_field,
  52                 publish_field_fn publish_field);
  53
  54 template <class UstCtlEncodingType>
  55 enum lst::null_terminated_string_type::encoding ust_ctl_encoding_to_string_field_encoding(UstCtlEncodingType encoding)
  56 {
  57         static const std::unordered_map<UstCtlEncodingType, enum lst::null_terminated_string_type::encoding>
  58                         encoding_conversion_map = {
  59                                         {(UstCtlEncodingType) lttng_ust_ctl_encode_ASCII,
  60                                                         lst::null_terminated_string_type::encoding::ASCII},
  61                                         {(UstCtlEncodingType) lttng_ust_ctl_encode_UTF8,
  62                                                         lst::null_terminated_string_type::encoding::UTF8},
  63                         };
  64
  65         const auto encoding_it = encoding_conversion_map.find(encoding);
  66         if (encoding_it == encoding_conversion_map.end()) {
  67                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
  68                                 "Unknown lttng_ust_ctl_string_encodings value `{}` encountered when decoding integer field",
  69                                 encoding));
  70         }
  71
  72         return encoding_it->second;
  73 }
  74
  75 template <class UstCtlBaseType>
  76 enum lst::integer_type::base ust_ctl_base_to_integer_field_base(UstCtlBaseType base)
  77 {
  78         static const std::unordered_map<UstCtlBaseType, enum lst::integer_type::base>
  79                         base_conversion_map = {{2, lst::integer_type::base::BINARY},
  80                                         {8, lst::integer_type::base::OCTAL},
  81                                         {10, lst::integer_type::base::DECIMAL},
  82                                         {16, lst::integer_type::base::HEXADECIMAL}};
  83
  84         const auto base_it = base_conversion_map.find(base);
  85         if (base_it == base_conversion_map.end()) {
  86                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
  87                                 "Unknown integer base value `{}` encountered when decoding integer field",
  88                                 base));
  89         }
  90
  91         return base_it->second;
  92 }
  93
  94 lst::type::cuptr create_integer_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
  95                 const lttng_ust_ctl_field *end,
  96                 const session_attributes& session_attributes,
  97                 const lttng_ust_ctl_field **next_ust_ctl_field)
  98 {
  99         if (current >= end) {
 100                 LTTNG_THROW_PROTOCOL_ERROR(
 101                                 fmt::format("End of {} array reached unexpectedly during decoding",
 102                                                 typeid(*current)));
 103         }
 104
 105         const auto base = ust_ctl_base_to_integer_field_base(current->type.u.integer.base);
 106         const auto signedness = current->type.u.integer.signedness ?
 107                         lst::integer_type::signedness::SIGNED :
 108                               lst::integer_type::signedness::UNSIGNED;
 109         const auto byte_order = current->type.u.integer.reverse_byte_order ?
 110                         lst::type::reverse_byte_order(session_attributes._native_trace_byte_order) :
 111                               session_attributes._native_trace_byte_order;
 112
 113         *next_ust_ctl_field = current + 1;
 114
 115         return lttng::make_unique<const lst::integer_type>(current->type.u.integer.alignment,
 116                         byte_order, current->type.u.integer.size, signedness, base);
 117 }
 118
 119 lst::type::cuptr create_floating_point_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 120                 const lttng_ust_ctl_field *end,
 121                 const session_attributes& session_attributes,
 122                 const lttng_ust_ctl_field **next_ust_ctl_field)
 123 {
 124         if (current >= end) {
 125                 LTTNG_THROW_PROTOCOL_ERROR(
 126                                 fmt::format("End of {} array reached unexpectedly during decoding",
 127                                                 typeid(*current)));
 128         }
 129
 130         *next_ust_ctl_field = current + 1;
 131
 132         const auto byte_order = current->type.u._float.reverse_byte_order ?
 133                         lst::type::reverse_byte_order(session_attributes._native_trace_byte_order) :
 134                               session_attributes._native_trace_byte_order;
 135
 136         try {
 137                 return lttng::make_unique<const lst::floating_point_type>(
 138                                 current->type.u._float.alignment, byte_order,
 139                                 current->type.u._float.exp_dig, current->type.u._float.mant_dig);
 140         } catch (lttng::invalid_argument_error& ex) {
 141                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format("Invalid floating point attribute in {}: {}",
 142                                 typeid(*current), ex.what()));
 143         }
 144 }
 145
 146 lst::type::cuptr create_enumeration_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 147                 const lttng_ust_ctl_field *end,
 148                 const session_attributes& session_attributes,
 149                 const lttng_ust_ctl_field **next_ust_ctl_field)
 150 {
 151         if (current >= end) {
 152                 LTTNG_THROW_PROTOCOL_ERROR(
 153                                 fmt::format("End of {} array reached unexpectedly during decoding",
 154                                                 typeid(*current)));
 155         }
 156
 157         uint64_t enumeration_id;
 158         const auto& enum_uctl_field = *current;
 159         const char *enumeration_name;
 160         const auto *enum_container_uctl_type =
 161                         &current->type.u.legacy.basic.enumeration.container_type;
 162
 163         if (enum_uctl_field.type.atype == lttng_ust_ctl_atype_enum_nestable) {
 164                 /* Nestable enumeration fields are followed by their container type. */
 165                 ++current;
 166                 if (current >= end) {
 167                         LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 168                                         "Array of {} is too short to contain nestable enumeration's container",
 169                                         typeid(*current)));
 170                 }
 171
 172                 if (current->type.atype != lttng_ust_ctl_atype_integer) {
 173                         LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 174                                         "Invalid type of nestable enum container: type id = {}",
 175                                         current->type.atype));
 176                 }
 177
 178                 enum_container_uctl_type = &current->type.u.integer;
 179                 enumeration_id = enum_uctl_field.type.u.enum_nestable.id;
 180                 enumeration_name = enum_uctl_field.type.u.enum_nestable.name;
 181         } else {
 182                 enumeration_id = enum_uctl_field.type.u.legacy.basic.enumeration.id;
 183                 enumeration_name = enum_uctl_field.type.u.legacy.basic.enumeration.name;
 184         }
 185
 186         *next_ust_ctl_field = current + 1;
 187
 188         const auto base = ust_ctl_base_to_integer_field_base(enum_container_uctl_type->base);
 189         const auto byte_order = enum_container_uctl_type->reverse_byte_order ?
 190                         lst::integer_type::reverse_byte_order(
 191                                         session_attributes._native_trace_byte_order) :
 192                               session_attributes._native_trace_byte_order;
 193         const auto signedness = enum_container_uctl_type->signedness ?
 194                         lst::integer_type::signedness::SIGNED :
 195                               lst::integer_type::signedness::UNSIGNED;
 196
 197         if (enum_container_uctl_type->signedness) {
 198                 const auto& enum_registry = static_cast<const lsu::registry_signed_enum&>(
 199                                 *session_attributes.get_registry_enum(
 200                                                 enumeration_name, enumeration_id));
 201
 202                 return lttng::make_unique<const lst::signed_enumeration_type>(
 203                                 enum_container_uctl_type->alignment, byte_order,
 204                                 enum_container_uctl_type->size, signedness, base,
 205                                 enum_registry._mappings);
 206         } else {
 207                 const auto& enum_registry = static_cast<const lsu::registry_unsigned_enum&>(
 208                                 *session_attributes.get_registry_enum(
 209                                                 enumeration_name, enumeration_id));
 210
 211                 return lttng::make_unique<const lst::unsigned_enumeration_type>(
 212                                 enum_container_uctl_type->alignment, byte_order,
 213                                 enum_container_uctl_type->size, signedness, base,
 214                                 enum_registry._mappings);
 215         }
 216 }
 217
 218 lst::type::cuptr create_string_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 219                 const lttng_ust_ctl_field *end,
 220                 const session_attributes& session_attributes __attribute__((unused)),
 221                 const lttng_ust_ctl_field **next_ust_ctl_field)
 222 {
 223         if (current >= end) {
 224                 LTTNG_THROW_PROTOCOL_ERROR(
 225                                 fmt::format("End of {} array reached unexpectedly during decoding",
 226                                                 typeid(*current)));
 227         }
 228
 229         const auto& string_uctl_field = *current;
 230         *next_ust_ctl_field = current + 1;
 231
 232         const auto encoding = ust_ctl_encoding_to_string_field_encoding(
 233                         string_uctl_field.type.u.string.encoding);
 234
 235         return lttng::make_unique<const lst::null_terminated_string_type>(1, encoding);
 236 }
 237
 238 lst::type::cuptr create_integer_type_from_ust_ctl_basic_type(
 239                 const lttng_ust_ctl_basic_type& type, const session_attributes& session_attributes)
 240 {
 241         /* Checked by caller. */
 242         LTTNG_ASSERT(type.atype == lttng_ust_ctl_atype_integer);
 243
 244         const auto byte_order = type.u.basic.integer.reverse_byte_order ?
 245                         lst::integer_type::reverse_byte_order(
 246                                         session_attributes._native_trace_byte_order) :
 247                               session_attributes._native_trace_byte_order;
 248         const auto signedness = type.u.basic.integer.signedness ?
 249                         lst::integer_type::signedness::SIGNED :
 250                               lst::integer_type::signedness::UNSIGNED;
 251         const auto base = ust_ctl_base_to_integer_field_base(type.u.basic.integer.base);
 252         const auto size = type.u.basic.integer.size;
 253         const auto alignment = type.u.basic.integer.alignment;
 254
 255         return lttng::make_unique<const lst::integer_type>(
 256                         alignment, byte_order, size, signedness, base);
 257 }
 258
 259 lst::type::cuptr create_array_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 260                 const lttng_ust_ctl_field *end,
 261                 const session_attributes& session_attributes,
 262                 const lttng_ust_ctl_field **next_ust_ctl_field)
 263 {
 264         if (current >= end) {
 265                 LTTNG_THROW_PROTOCOL_ERROR(
 266                                 fmt::format("End of {} array reached unexpectedly during decoding",
 267                                                 typeid(*current)));
 268         }
 269
 270         const auto& array_uctl_field = *current;
 271         uint32_t array_alignment, array_length;
 272         lst::type::cuptr element_type;
 273         nonstd::optional<enum lst::string_type::encoding> element_encoding;
 274
 275         array_length = array_uctl_field.type.u.legacy.array.length;
 276         array_alignment = 0;
 277
 278         const auto& element_uctl_type = array_uctl_field.type.u.legacy.array.elem_type;
 279         if (element_uctl_type.atype != lttng_ust_ctl_atype_integer) {
 280                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 281                                 "Unexpected legacy array element type: atype = {}, expected atype = lttng_ust_ctl_atype_integer ({})",
 282                                 element_uctl_type.atype, lttng_ust_ctl_atype_integer));
 283         }
 284
 285         element_type = create_integer_type_from_ust_ctl_basic_type(
 286                         element_uctl_type, session_attributes);
 287         if (element_uctl_type.atype == lttng_ust_ctl_atype_integer &&
 288                         element_uctl_type.u.basic.integer.encoding != lttng_ust_ctl_encode_none) {
 289                 /* Element represents a text character. */
 290                 element_encoding = ust_ctl_encoding_to_string_field_encoding(
 291                                 element_uctl_type.u.basic.integer.encoding);
 292         }
 293
 294         *next_ust_ctl_field = current + 1;
 295
 296         if (element_encoding) {
 297                 const auto integer_element_size =
 298                                 static_cast<const lst::integer_type&>(*element_type).size;
 299
 300                 if (integer_element_size != 8) {
 301                         LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 302                                         "Unexpected legacy array element type: integer has encoding but size is not 8: size = {}",
 303                                         integer_element_size));
 304                 }
 305
 306                 /* Array is a static-length string. */
 307                 return lttng::make_unique<lst::static_length_string_type>(
 308                                 array_alignment, *element_encoding, array_length);
 309         }
 310
 311         return lttng::make_unique<lst::static_length_array_type>(
 312                         array_alignment, std::move(element_type), array_length);
 313 }
 314
 315 lst::type::cuptr create_array_nestable_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 316                 const lttng_ust_ctl_field *end,
 317                 const session_attributes& session_attributes,
 318                 const lttng_ust_ctl_field **next_ust_ctl_field,
 319                 publish_field_fn publish_field)
 320 {
 321         if (current >= end) {
 322                 LTTNG_THROW_PROTOCOL_ERROR(
 323                                 fmt::format("End of {} array reached unexpectedly during decoding",
 324                                                 typeid(*current)));
 325         }
 326
 327         const auto& array_uctl_field = *current;
 328         uint32_t array_alignment, array_length;
 329         lst::type::cuptr element_type;
 330         nonstd::optional<enum lst::string_type::encoding> element_encoding;
 331
 332         array_length = array_uctl_field.type.u.array_nestable.length;
 333         array_alignment = array_uctl_field.type.u.array_nestable.alignment;
 334
 335         /* Nestable array fields are followed by their element type. */
 336         const auto& element_uctl_field = *(current + 1);
 337
 338         /* next_ust_ctl_field is updated as needed. */
 339         element_type = create_type_from_ust_ctl_fields(&element_uctl_field, end, session_attributes,
 340                         next_ust_ctl_field, publish_field);
 341         if (element_uctl_field.type.atype == lttng_ust_ctl_atype_integer &&
 342                         element_uctl_field.type.u.integer.encoding != lttng_ust_ctl_encode_none) {
 343                 /* Element represents a text character. */
 344                 element_encoding = ust_ctl_encoding_to_string_field_encoding(
 345                                 element_uctl_field.type.u.integer.encoding);
 346         }
 347
 348         if (element_encoding) {
 349                 const auto integer_element_size =
 350                                 static_cast<const lst::integer_type&>(*element_type).size;
 351
 352                 if (integer_element_size != 8) {
 353                         LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 354                                         "Unexpected array element type: integer has encoding but size is not 8: size = {}",
 355                                         integer_element_size));
 356                 }
 357
 358                 /* Array is a static-length string. */
 359                 return lttng::make_unique<lst::static_length_string_type>(
 360                                 array_alignment, *element_encoding, array_length);
 361         }
 362
 363         return lttng::make_unique<lst::static_length_array_type>(
 364                         array_alignment, std::move(element_type), array_length);
 365 }
 366
 367 /*
 368  * For legacy sequence types, LTTng-UST expresses both the sequence and sequence
 369  * length as part of the same lttng_ust_ctl_field entry.
 370  */
 371 lst::type::cuptr create_sequence_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 372                 const lttng_ust_ctl_field *end,
 373                 const session_attributes& session_attributes,
 374                 const lttng_ust_ctl_field **next_ust_ctl_field,
 375                 publish_field_fn publish_field)
 376 {
 377         if (current >= end) {
 378                 LTTNG_THROW_PROTOCOL_ERROR(
 379                                 fmt::format("End of {} array reached unexpectedly during decoding",
 380                                                 typeid(*current)));
 381         }
 382
 383         const auto& sequence_uctl_field = *current;
 384         const auto& element_uctl_type = sequence_uctl_field.type.u.legacy.sequence.elem_type;
 385         const auto& length_uctl_type = sequence_uctl_field.type.u.legacy.sequence.length_type;
 386         const auto sequence_alignment = 0U;
 387
 388         if (element_uctl_type.atype != lttng_ust_ctl_atype_integer) {
 389                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 390                                 "Unexpected legacy sequence element type: atype = {}, expected atype = lttng_ust_ctl_atype_integer ({})",
 391                                 element_uctl_type.atype, lttng_ust_ctl_atype_integer));
 392         }
 393
 394         if (length_uctl_type.atype != lttng_ust_ctl_atype_integer) {
 395                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 396                                 "Unexpected legacy sequence length field type: atype = {}, expected atype = lttng_ust_ctl_atype_integer ({})",
 397                                 length_uctl_type.atype, lttng_ust_ctl_atype_integer));
 398         }
 399
 400         nonstd::optional<enum lst::string_type::encoding> element_encoding;
 401         if (element_uctl_type.atype == lttng_ust_ctl_atype_integer &&
 402                         element_uctl_type.u.basic.integer.encoding != lttng_ust_ctl_encode_none) {
 403                 /* Element represents a text character. */
 404                 element_encoding = ust_ctl_encoding_to_string_field_encoding(
 405                                 element_uctl_type.u.basic.integer.encoding);
 406         }
 407
 408         const auto length_field_name = fmt::format("_{}_length", sequence_uctl_field.name);
 409         auto element_type = create_integer_type_from_ust_ctl_basic_type(
 410                         element_uctl_type, session_attributes);
 411         auto length_type = create_integer_type_from_ust_ctl_basic_type(
 412                         length_uctl_type, session_attributes);
 413
 414         /* Publish an implicit length field _before_ the sequence field. */
 415         publish_field(lttng::make_unique<lst::field>(length_field_name, std::move(length_type)));
 416
 417         *next_ust_ctl_field = current + 1;
 418
 419         if (element_encoding) {
 420                 const auto integer_element_size =
 421                                 static_cast<const lst::integer_type&>(*element_type).size;
 422
 423                 if (integer_element_size != 8) {
 424                         LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 425                                         "Unexpected legacy array element type: integer has encoding but size is not 8: size = {}",
 426                                         integer_element_size));
 427                 }
 428
 429                 /* Sequence is a dynamic-length string. */
 430                 return lttng::make_unique<lst::dynamic_length_string_type>(sequence_alignment,
 431                                 *element_encoding, std::move(length_field_name));
 432         }
 433
 434         return lttng::make_unique<lst::dynamic_length_array_type>(
 435                         sequence_alignment, std::move(element_type), std::move(length_field_name));
 436 }
 437
 438 lst::type::cuptr create_sequence_nestable_type_from_ust_ctl_fields(
 439                 const lttng_ust_ctl_field *current,
 440                 const lttng_ust_ctl_field *end,
 441                 const session_attributes& session_attributes,
 442                 const lttng_ust_ctl_field **next_ust_ctl_field,
 443                 publish_field_fn publish_field)
 444 {
 445         if (current >= end) {
 446                 LTTNG_THROW_PROTOCOL_ERROR(
 447                                 fmt::format("End of {} array reached unexpectedly during decoding",
 448                                                 typeid(*current)));
 449         }
 450
 451         const auto& sequence_uctl_field = *current;
 452         const auto sequence_alignment = sequence_uctl_field.type.u.sequence_nestable.alignment;
 453         const auto *length_field_name = sequence_uctl_field.type.u.sequence_nestable.length_name;
 454
 455         /* Nestable sequence fields are followed by their element type. */
 456         const auto& element_uctl_field = *(current + 1);
 457
 458         nonstd::optional<enum lst::string_type::encoding> element_encoding;
 459         if (element_uctl_field.type.atype == lttng_ust_ctl_atype_integer &&
 460                         element_uctl_field.type.u.integer.encoding != lttng_ust_ctl_encode_none) {
 461                 /* Element represents a text character. */
 462                 element_encoding = ust_ctl_encoding_to_string_field_encoding(
 463                                 element_uctl_field.type.u.integer.encoding);
 464         }
 465
 466         /* next_ust_ctl_field is updated as needed. */
 467         auto element_type = create_type_from_ust_ctl_fields(&element_uctl_field, end,
 468                         session_attributes, next_ust_ctl_field, publish_field);
 469
 470         if (lttng_strnlen(sequence_uctl_field.type.u.sequence_nestable.length_name,
 471                             sizeof(sequence_uctl_field.type.u.sequence_nestable.length_name)) ==
 472                         sizeof(sequence_uctl_field.type.u.sequence_nestable.length_name)) {
 473                 LTTNG_THROW_PROTOCOL_ERROR("Sequence length field name is not null terminated");
 474         }
 475
 476         if (element_encoding) {
 477                 const auto integer_element_size =
 478                                 static_cast<const lst::integer_type&>(*element_type).size;
 479
 480                 if (integer_element_size != 8) {
 481                         LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 482                                         "Unexpected array element type: integer has encoding but size is not 8: size = {}",
 483                                         integer_element_size));
 484                 }
 485
 486                 /* Sqeuence is a dynamic-length string. */
 487                 return lttng::make_unique<lst::dynamic_length_string_type>(sequence_alignment,
 488                                 *element_encoding, std::move(length_field_name));
 489         }
 490
 491         return lttng::make_unique<lst::dynamic_length_array_type>(
 492                         sequence_alignment, std::move(element_type), std::move(length_field_name));
 493 }
 494
 495 lst::type::cuptr create_structure_field_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 496                 const lttng_ust_ctl_field *end,
 497                 const session_attributes& session_attributes __attribute__((unused)),
 498                 const lttng_ust_ctl_field **next_ust_ctl_field)
 499 {
 500         if (current >= end) {
 501                 LTTNG_THROW_PROTOCOL_ERROR(
 502                                 fmt::format("End of {} array reached unexpectedly during decoding",
 503                                                 typeid(*current)));
 504         }
 505
 506         uint32_t field_count;
 507         uint32_t alignment;
 508         const auto& structure_uctl_field = *current;
 509
 510         if (structure_uctl_field.type.atype == lttng_ust_ctl_atype_struct) {
 511                 field_count = structure_uctl_field.type.u.legacy._struct.nr_fields;
 512                 alignment = 0;
 513         } else {
 514                 field_count = structure_uctl_field.type.u.struct_nestable.nr_fields;
 515                 alignment = structure_uctl_field.type.u.struct_nestable.alignment;
 516         }
 517
 518         if (field_count != 0) {
 519                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 520                                 "Only empty structures are supported by LTTng-UST: nr_fields = {}",
 521                                 field_count));
 522         }
 523
 524         *next_ust_ctl_field = current + 1;
 525         return lttng::make_unique<lst::structure_type>(alignment, lst::structure_type::fields());
 526 }
 527
 528 lst::type::cuptr create_variant_field_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 529                 const lttng_ust_ctl_field *end,
 530                 const session_attributes& session_attributes,
 531                 const lttng_ust_ctl_field **next_ust_ctl_field)
 532 {
 533         if (current >= end) {
 534                 LTTNG_THROW_PROTOCOL_ERROR(
 535                                 fmt::format("End of {} array reached unexpectedly during decoding",
 536                                                 typeid(*current)));
 537         }
 538
 539         const auto& variant_uctl_field = *current;
 540         current++;
 541
 542         uint32_t alignment;
 543         uint32_t choice_count;
 544         const char *tag_name;
 545
 546         if (variant_uctl_field.type.atype == lttng_ust_ctl_atype_variant) {
 547                 alignment = 0;
 548                 choice_count = variant_uctl_field.type.u.legacy.variant.nr_choices;
 549                 tag_name = variant_uctl_field.type.u.legacy.variant.tag_name;
 550         } else {
 551                 alignment = variant_uctl_field.type.u.variant_nestable.alignment;
 552                 choice_count = variant_uctl_field.type.u.variant_nestable.nr_choices;
 553                 tag_name = variant_uctl_field.type.u.variant_nestable.tag_name;
 554         }
 555
 556         /* Choices follow. next_ust_ctl_field is updated as needed. */
 557         lst::variant_type::choices choices;
 558         for (unsigned int i = 0; i < choice_count; i++) {
 559                 create_field_from_ust_ctl_fields(current, end, session_attributes,
 560                                 next_ust_ctl_field, [&choices](lst::field::cuptr field) {
 561                                         choices.emplace_back(std::move(field));
 562                                 });
 563
 564                 current = *next_ust_ctl_field;
 565         }
 566
 567         return lttng::make_unique<lst::variant_type>(alignment, tag_name, std::move(choices));
 568 }
 569
 570 lst::type::cuptr create_type_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 571                 const lttng_ust_ctl_field *end,
 572                 const session_attributes& session_attributes,
 573                 const lttng_ust_ctl_field **next_ust_ctl_field,
 574                 publish_field_fn publish_field)
 575 {
 576         switch (current->type.atype) {
 577         case lttng_ust_ctl_atype_integer:
 578                 return create_integer_type_from_ust_ctl_fields(
 579                                 current, end, session_attributes, next_ust_ctl_field);
 580         case lttng_ust_ctl_atype_enum:
 581         case lttng_ust_ctl_atype_enum_nestable:
 582                 return create_enumeration_type_from_ust_ctl_fields(
 583                                 current, end, session_attributes, next_ust_ctl_field);
 584         case lttng_ust_ctl_atype_float:
 585                 return create_floating_point_type_from_ust_ctl_fields(
 586                                 current, end, session_attributes, next_ust_ctl_field);
 587         case lttng_ust_ctl_atype_string:
 588                 return create_string_type_from_ust_ctl_fields(
 589                                 current, end, session_attributes, next_ust_ctl_field);
 590         case lttng_ust_ctl_atype_array:
 591                 return create_array_type_from_ust_ctl_fields(current, end, session_attributes,
 592                                 next_ust_ctl_field);
 593         case lttng_ust_ctl_atype_array_nestable:
 594                 return create_array_nestable_type_from_ust_ctl_fields(current, end,
 595                                 session_attributes, next_ust_ctl_field, publish_field);
 596         case lttng_ust_ctl_atype_sequence:
 597                 return create_sequence_type_from_ust_ctl_fields(current, end, session_attributes,
 598                                 next_ust_ctl_field, publish_field);
 599         case lttng_ust_ctl_atype_sequence_nestable:
 600                 return create_sequence_nestable_type_from_ust_ctl_fields(current, end,
 601                                 session_attributes, next_ust_ctl_field, publish_field);
 602         case lttng_ust_ctl_atype_struct:
 603         case lttng_ust_ctl_atype_struct_nestable:
 604                 return create_structure_field_from_ust_ctl_fields(
 605                                 current, end, session_attributes, next_ust_ctl_field);
 606         case lttng_ust_ctl_atype_variant:
 607         case lttng_ust_ctl_atype_variant_nestable:
 608                 return create_variant_field_from_ust_ctl_fields(
 609                                 current, end, session_attributes, next_ust_ctl_field);
 610         default:
 611                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 612                                 "Unknown {} value `{}` encountered while converting {} to {}",
 613                                 typeid(current->type.atype), current->type.atype, typeid(*current),
 614                                 typeid(lst::type::cuptr::element_type)));
 615         }
 616 }
 617
 618 void create_field_from_ust_ctl_fields(const lttng_ust_ctl_field *current,
 619                 const lttng_ust_ctl_field *end,
 620                 const session_attributes& session_attributes,
 621                 const lttng_ust_ctl_field **next_ust_ctl_field,
 622                 publish_field_fn publish_field)
 623 {
 624         LTTNG_ASSERT(current < end);
 625
 626         if (lttng_strnlen(current->name, sizeof(current->name)) == sizeof(current->name)) {
 627                 LTTNG_THROW_PROTOCOL_ERROR(
 628                                 fmt::format("Name of {} is not null-terminated", typeid(*current)));
 629         }
 630
 631         publish_field(lttng::make_unique<lst::field>(current->name,
 632                         create_type_from_ust_ctl_fields(current, end, session_attributes,
 633                                         next_ust_ctl_field, publish_field)));
 634 }
 635
 636 /*
 637  * `lttng_ust_ctl_field`s can be nested, in which case creating a field will consume
 638  * more than one lttng_ust_ctl_field. create_field_from_ust_ctl_fields returns the
 639  * position of the next lttng_ust_ctl_field to consume or `end` when the last field
 640  * is consumed.
 641  *
 642  * Always returns a new field, throws on error.
 643  */
 644 std::vector<lst::field::cuptr> create_fields_from_ust_ctl_fields(
 645                 const lsu::registry_session& session,
 646                 const lttng_ust_ctl_field *current,
 647                 const lttng_ust_ctl_field *end)
 648 {
 649         std::vector<lst::field::cuptr> fields;
 650         const auto trace_native_byte_order = session.abi.byte_order;
 651         const session_attributes session_attributes{
 652                         [&session](const char *enum_name, uint64_t enum_id) {
 653                                 return ust_registry_lookup_enum_by_id(&session, enum_name, enum_id);
 654                         },
 655                         trace_native_byte_order};
 656
 657         while (current < end) {
 658                 auto *next_field = current;
 659
 660                 /*
 661                  * create_field_from_ust_ctl_fields will consume one field at a time.
 662                  * However, some fields expressed by LTTng-UST's protocol are expended
 663                  * to multiple event fields (legacy sequence fields implicitly define
 664                  * their length field).
 665                  *
 666                  * The lambda allows the factory functions to push as many fields as
 667                  * needed depending on the decoded field's type.
 668                  */
 669                 create_field_from_ust_ctl_fields(current, end, session_attributes, &next_field,
 670                                 [&fields](lst::field::cuptr field) {
 671                                         fields.emplace_back(std::move(field));
 672                                 });
 673
 674                 current = next_field;
 675         }
 676
 677         return fields;
 678 }
 679 } /* namespace */
 680
 681 std::vector<lst::field::cuptr> lsu::create_trace_fields_from_ust_ctl_fields(
 682                 const lsu::registry_session& session,
 683                 const lttng_ust_ctl_field *fields,
 684                 std::size_t field_count)
 685 {
 686         return create_fields_from_ust_ctl_fields(session, fields, fields + field_count);
 687 }