Add loglevel in TSDL examples
[ctf.git] / common-trace-format-specification.txt
1 Common Trace Format (CTF) Specification (pre-v1.8)
2
3 Mathieu Desnoyers, EfficiOS Inc.
4
5 The goal of the present document is to specify a trace format that suits the
6 needs of the embedded, telecom, high-performance and kernel communities. It is
7 based on the Common Trace Format Requirements (v1.4) document. It is designed to
8 allow traces to be natively generated by the Linux kernel, Linux user-space
9 applications written in C/C++, and hardware components. One major element of
10 CTF is the Trace Stream Description Language (TSDL) which flexibility
11 enables description of various binary trace stream layouts.
12
13 The latest version of this document can be found at:
14
15 git tree: git://git.efficios.com/ctf.git
16 gitweb: http://git.efficios.com/?p=ctf.git
17
18 A reference implementation of a library to read and write this trace format is
19 being implemented within the BabelTrace project, a converter between trace
20 formats. The development tree is available at:
21
22 git tree: git://git.efficios.com/babeltrace.git
23 gitweb: http://git.efficios.com/?p=babeltrace.git
24
25 The CE Workgroup of the Linux Foundation, Ericsson, and EfficiOS have
26 sponsored this work.
27
28
29 Table of Contents
30
31 1. Preliminary definitions
32 2. High-level representation of a trace
33 3. Event stream
34 4. Types
35 4.1 Basic types
36 4.1.1 Type inheritance
37 4.1.2 Alignment
38 4.1.3 Byte order
39 4.1.4 Size
40 4.1.5 Integers
41 4.1.6 GNU/C bitfields
42 4.1.7 Floating point
43 4.1.8 Enumerations
44 4.2 Compound types
45 4.2.1 Structures
46 4.2.2 Variants (Discriminated/Tagged Unions)
47 4.2.3 Arrays
48 4.2.4 Sequences
49 4.2.5 Strings
50 5. Event Packet Header
51 5.1 Event Packet Header Description
52 5.2 Event Packet Context Description
53 6. Event Structure
54 6.1 Event Header
55 6.1.1 Type 1 - Few event IDs
56 6.1.2 Type 2 - Many event IDs
57 6.2 Event Context
58 6.3 Event Payload
59 6.3.1 Padding
60 6.3.2 Alignment
61 7. Trace Stream Description Language (TSDL)
62 7.1 Meta-data
63 7.2 Declaration vs Definition
64 7.3 TSDL Scopes
65 7.3.1 Lexical Scope
66 7.3.2 Static and Dynamic Scopes
67 7.4 TSDL Examples
68
69
70 1. Preliminary definitions
71
72 - Event Trace: An ordered sequence of events.
73 - Event Stream: An ordered sequence of events, containing a subset of the
74 trace event types.
75 - Event Packet: A sequence of physically contiguous events within an event
76 stream.
77 - Event: This is the basic entry in a trace. (aka: a trace record).
78 - An event identifier (ID) relates to the class (a type) of event within
79 an event stream.
80 e.g. event: irq_entry.
81 - An event (or event record) relates to a specific instance of an event
82 class.
83 e.g. event: irq_entry, at time X, on CPU Y
84 - Source Architecture: Architecture writing the trace.
85 - Reader Architecture: Architecture reading the trace.
86
87
88 2. High-level representation of a trace
89
90 A trace is divided into multiple event streams. Each event stream contains a
91 subset of the trace event types.
92
93 The final output of the trace, after its generation and optional transport over
94 the network, is expected to be either on permanent or temporary storage in a
95 virtual file system. Because each event stream is appended to while a trace is
96 being recorded, each is associated with a distinct set of files for
97 output. Therefore, a stored trace can be represented as a directory
98 containing zero, one or more files per stream.
99
100 Meta-data description associated with the trace contains information on
101 trace event types expressed in the Trace Stream Description Language
102 (TSDL). This language describes:
103
104 - Trace version.
105 - Types available.
106 - Per-trace event header description.
107 - Per-stream event header description.
108 - Per-stream event context description.
109 - Per-event
110 - Event type to stream mapping.
111 - Event type to name mapping.
112 - Event type to ID mapping.
113 - Event context description.
114 - Event fields description.
115
116
117 3. Event stream
118
119 An event stream can be divided into contiguous event packets of variable
120 size. These subdivisions have a variable size. An event packet can
121 contain a certain amount of padding at the end. The stream header is
122 repeated at the beginning of each event packet. The rationale for the
123 event stream design choices is explained in Appendix B. Stream Header
124 Rationale.
125
126 The event stream header will therefore be referred to as the "event packet
127 header" throughout the rest of this document.
128
129
130 4. Types
131
132 Types are organized as type classes. Each type class belong to either of two
133 kind of types: basic types or compound types.
134
135 4.1 Basic types
136
137 A basic type is a scalar type, as described in this section. It includes
138 integers, GNU/C bitfields, enumerations, and floating point values.
139
140 4.1.1 Type inheritance
141
142 Type specifications can be inherited to allow deriving types from a
143 type class. For example, see the uint32_t named type derived from the "integer"
144 type class below ("Integers" section). Types have a precise binary
145 representation in the trace. A type class has methods to read and write these
146 types, but must be derived into a type to be usable in an event field.
147
148 4.1.2 Alignment
149
150 We define "byte-packed" types as aligned on the byte size, namely 8-bit.
151 We define "bit-packed" types as following on the next bit, as defined by the
152 "Integers" section.
153
154 Each basic type must specify its alignment, in bits. Examples of
155 possible alignments are: bit-packed (align = 1), byte-packed (align =
156 8), or word-aligned (e.g. align = 32 or align = 64). The choice depends
157 on the architecture preference and compactness vs performance trade-offs
158 of the implementation. Architectures providing fast unaligned write
159 byte-packed basic types to save space, aligning each type on byte
160 boundaries (8-bit). Architectures with slow unaligned writes align types
161 on specific alignment values. If no specific alignment is declared for a
162 type, it is assumed to be bit-packed for integers with size not multiple
163 of 8 bits and for gcc bitfields. All other basic types are byte-packed
164 by default. It is however recommended to always specify the alignment
165 explicitly. Alignment values must be power of two. Compound types are
166 aligned as specified in their individual specification.
167
168 TSDL meta-data attribute representation of a specific alignment:
169
170 align = value; /* value in bits */
171
172 4.1.3 Byte order
173
174 By default, the native endianness of the source architecture the trace is used.
175 Byte order can be overridden for a basic type by specifying a "byte_order"
176 attribute. Typical use-case is to specify the network byte order (big endian:
177 "be") to save data captured from the network into the trace without conversion.
178 If not specified, the byte order is native.
179
180 TSDL meta-data representation:
181
182 byte_order = native OR network OR be OR le; /* network and be are aliases */
183
184 4.1.4 Size
185
186 Type size, in bits, for integers and floats is that returned by "sizeof()" in C
187 multiplied by CHAR_BIT.
188 We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
189 to 8 bits for cross-endianness compatibility.
190
191 TSDL meta-data representation:
192
193 size = value; (value is in bits)
194
195 4.1.5 Integers
196
197 Signed integers are represented in two-complement. Integer alignment,
198 size, signedness and byte ordering are defined in the TSDL meta-data.
199 Integers aligned on byte size (8-bit) and with length multiple of byte
200 size (8-bit) correspond to the C99 standard integers. In addition,
201 integers with alignment and/or size that are _not_ a multiple of the
202 byte size are permitted; these correspond to the C99 standard bitfields,
203 with the added specification that the CTF integer bitfields have a fixed
204 binary representation. A MIT-licensed reference implementation of the
205 CTF portable bitfields is available at:
206
207 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
208
209 Binary representation of integers:
210
211 - On little and big endian:
212 - Within a byte, high bits correspond to an integer high bits, and low bits
213 correspond to low bits.
214 - On little endian:
215 - Integer across multiple bytes are placed from the less significant to the
216 most significant.
217 - Consecutive integers are placed from lower bits to higher bits (even within
218 a byte).
219 - On big endian:
220 - Integer across multiple bytes are placed from the most significant to the
221 less significant.
222 - Consecutive integers are placed from higher bits to lower bits (even within
223 a byte).
224
225 This binary representation is derived from the bitfield implementation in GCC
226 for little and big endian. However, contrary to what GCC does, integers can
227 cross units boundaries (no padding is required). Padding can be explicitly
228 added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
229
230 TSDL meta-data representation:
231
232 integer {
233 signed = true OR false; /* default false */
234 byte_order = native OR network OR be OR le; /* default native */
235 size = value; /* value in bits, no default */
236 align = value; /* value in bits */
237 /* based used for pretty-printing output, default: decimal. */
238 base = decimal OR dec OR OR d OR i OR u OR 10 OR hexadecimal OR hex OR x OR X OR p OR 16
239 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
240 /* character encoding, default: none */
241 encoding = none or UTF8 or ASCII;
242 }
243
244 Example of type inheritance (creation of a uint32_t named type):
245
246 typealias integer {
247 size = 32;
248 signed = false;
249 align = 32;
250 } := uint32_t;
251
252 Definition of a named 5-bit signed bitfield:
253
254 typealias integer {
255 size = 5;
256 signed = true;
257 align = 1;
258 } := int5_t;
259
260 The character encoding field can be used to specify that the integer
261 must be printed as a text character when read. e.g.:
262
263 typealias integer {
264 size = 8;
265 align = 8;
266 signed = false;
267 encoding = UTF8;
268 } := utf_char;
269
270
271 4.1.6 GNU/C bitfields
272
273 The GNU/C bitfields follow closely the integer representation, with a
274 particularity on alignment: if a bitfield cannot fit in the current unit, the
275 unit is padded and the bitfield starts at the following unit. The unit size is
276 defined by the size of the type "unit_type".
277
278 TSDL meta-data representation:
279
280 unit_type name:size;
281
282 As an example, the following structure declared in C compiled by GCC:
283
284 struct example {
285 short a:12;
286 short b:5;
287 };
288
289 The example structure is aligned on the largest element (short). The second
290 bitfield would be aligned on the next unit boundary, because it would not fit in
291 the current unit.
292
293 4.1.7 Floating point
294
295 The floating point values byte ordering is defined in the TSDL meta-data.
296
297 Floating point values follow the IEEE 754-2008 standard interchange formats.
298 Description of the floating point values include the exponent and mantissa size
299 in bits. Some requirements are imposed on the floating point values:
300
301 - FLT_RADIX must be 2.
302 - mant_dig is the number of digits represented in the mantissa. It is specified
303 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
304 LDBL_MANT_DIG as defined by <float.h>.
305 - exp_dig is the number of digits represented in the exponent. Given that
306 mant_dig is one bit more than its actual size in bits (leading 1 is not
307 needed) and also given that the sign bit always takes one bit, exp_dig can be
308 specified as:
309
310 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
311 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
312 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
313
314 TSDL meta-data representation:
315
316 floating_point {
317 exp_dig = value;
318 mant_dig = value;
319 byte_order = native OR network OR be OR le;
320 align = value;
321 }
322
323 Example of type inheritance:
324
325 typealias floating_point {
326 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
327 mant_dig = 24; /* FLT_MANT_DIG */
328 byte_order = native;
329 align = 32;
330 } := float;
331
332 TODO: define NaN, +inf, -inf behavior.
333
334 Bit-packed, byte-packed or larger alignments can be used for floating
335 point values, similarly to integers.
336
337 4.1.8 Enumerations
338
339 Enumerations are a mapping between an integer type and a table of strings. The
340 numerical representation of the enumeration follows the integer type specified
341 by the meta-data. The enumeration mapping table is detailed in the enumeration
342 description within the meta-data. The mapping table maps inclusive value
343 ranges (or single values) to strings. Instead of being limited to simple
344 "value -> string" mappings, these enumerations map
345 "[ start_value ... end_value ] -> string", which map inclusive ranges of
346 values to strings. An enumeration from the C language can be represented in
347 this format by having the same start_value and end_value for each element, which
348 is in fact a range of size 1. This single-value range is supported without
349 repeating the start and end values with the value = string declaration.
350
351 enum name : integer_type {
352 somestring = start_value1 ... end_value1,
353 "other string" = start_value2 ... end_value2,
354 yet_another_string, /* will be assigned to end_value2 + 1 */
355 "some other string" = value,
356 ...
357 };
358
359 If the values are omitted, the enumeration starts at 0 and increment of 1 for
360 each entry:
361
362 enum name : unsigned int {
363 ZERO,
364 ONE,
365 TWO,
366 TEN = 10,
367 ELEVEN,
368 };
369
370 Overlapping ranges within a single enumeration are implementation defined.
371
372 A nameless enumeration can be declared as a field type or as part of a typedef:
373
374 enum : integer_type {
375 ...
376 }
377
378 Enumerations omitting the container type ": integer_type" use the "int"
379 type (for compatibility with C99). The "int" type must be previously
380 declared. E.g.:
381
382 typealias integer { size = 32; align = 32; signed = true } := int;
383
384 enum {
385 ...
386 }
387
388
389 4.2 Compound types
390
391 Compound are aggregation of type declarations. Compound types include
392 structures, variant, arrays, sequences, and strings.
393
394 4.2.1 Structures
395
396 Structures are aligned on the largest alignment required by basic types
397 contained within the structure. (This follows the ISO/C standard for structures)
398
399 TSDL meta-data representation of a named structure:
400
401 struct name {
402 field_type field_name;
403 field_type field_name;
404 ...
405 };
406
407 Example:
408
409 struct example {
410 integer { /* Nameless type */
411 size = 16;
412 signed = true;
413 align = 16;
414 } first_field_name;
415 uint64_t second_field_name; /* Named type declared in the meta-data */
416 };
417
418 The fields are placed in a sequence next to each other. They each
419 possess a field name, which is a unique identifier within the structure.
420 The identifier is not allowed to use any reserved keyword
421 (see Section C.1.2). Replacing reserved keywords with
422 underscore-prefixed field names is recommended.
423
424 A nameless structure can be declared as a field type or as part of a typedef:
425
426 struct {
427 ...
428 }
429
430 Alignment for a structure compound type can be forced to a minimum value
431 by adding an "align" specifier after the declaration of a structure
432 body. This attribute is read as: align(value). The value is specified in
433 bits. The structure will be aligned on the maximum value between this
434 attribute and the alignment required by the basic types contained within
435 the structure. e.g.
436
437 struct {
438 ...
439 } align(32)
440
441 4.2.2 Variants (Discriminated/Tagged Unions)
442
443 A CTF variant is a selection between different types. A CTF variant must
444 always be defined within the scope of a structure or within fields
445 contained within a structure (defined recursively). A "tag" enumeration
446 field must appear in either the same static scope, prior to the variant
447 field (in field declaration order), in an upper static scope , or in an
448 upper dynamic scope (see Section 7.3.2). The type selection is indicated
449 by the mapping from the enumeration value to the string used as variant
450 type selector. The field to use as tag is specified by the "tag_field",
451 specified between "< >" after the "variant" keyword for unnamed
452 variants, and after "variant name" for named variants.
453
454 The alignment of the variant is the alignment of the type as selected by the tag
455 value for the specific instance of the variant. The alignment of the type
456 containing the variant is independent of the variant alignment. The size of the
457 variant is the size as selected by the tag value for the specific instance of
458 the variant.
459
460 Each variant type selector possess a field name, which is a unique
461 identifier within the variant. The identifier is not allowed to use any
462 reserved keyword (see Section C.1.2). Replacing reserved keywords with
463 underscore-prefixed field names is recommended.
464
465 A named variant declaration followed by its definition within a structure
466 declaration:
467
468 variant name {
469 field_type sel1;
470 field_type sel2;
471 field_type sel3;
472 ...
473 };
474
475 struct {
476 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
477 ...
478 variant name <tag_field> v;
479 }
480
481 An unnamed variant definition within a structure is expressed by the following
482 TSDL meta-data:
483
484 struct {
485 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
486 ...
487 variant <tag_field> {
488 field_type sel1;
489 field_type sel2;
490 field_type sel3;
491 ...
492 } v;
493 }
494
495 Example of a named variant within a sequence that refers to a single tag field:
496
497 variant example {
498 uint32_t a;
499 uint64_t b;
500 short c;
501 };
502
503 struct {
504 enum : uint2_t { a, b, c } choice;
505 unsigned int seqlen;
506 variant example <choice> v[seqlen];
507 }
508
509 Example of an unnamed variant:
510
511 struct {
512 enum : uint2_t { a, b, c, d } choice;
513 /* Unrelated fields can be added between the variant and its tag */
514 int32_t somevalue;
515 variant <choice> {
516 uint32_t a;
517 uint64_t b;
518 short c;
519 struct {
520 unsigned int field1;
521 uint64_t field2;
522 } d;
523 } s;
524 }
525
526 Example of an unnamed variant within an array:
527
528 struct {
529 enum : uint2_t { a, b, c } choice;
530 variant <choice> {
531 uint32_t a;
532 uint64_t b;
533 short c;
534 } v[10];
535 }
536
537 Example of a variant type definition within a structure, where the defined type
538 is then declared within an array of structures. This variant refers to a tag
539 located in an upper static scope. This example clearly shows that a variant
540 type definition referring to the tag "x" uses the closest preceding field from
541 the static scope of the type definition.
542
543 struct {
544 enum : uint2_t { a, b, c, d } x;
545
546 typedef variant <x> { /*
547 * "x" refers to the preceding "x" enumeration in the
548 * static scope of the type definition.
549 */
550 uint32_t a;
551 uint64_t b;
552 short c;
553 } example_variant;
554
555 struct {
556 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
557 example_variant v; /*
558 * "v" uses the "enum : uint2_t { a, b, c, d }"
559 * tag.
560 */
561 } a[10];
562 }
563
564 4.2.3 Arrays
565
566 Arrays are fixed-length. Their length is declared in the type
567 declaration within the meta-data. They contain an array of "inner type"
568 elements, which can refer to any type not containing the type of the
569 array being declared (no circular dependency). The length is the number
570 of elements in an array.
571
572 TSDL meta-data representation of a named array:
573
574 typedef elem_type name[length];
575
576 A nameless array can be declared as a field type within a structure, e.g.:
577
578 uint8_t field_name[10];
579
580 Arrays are always aligned on their element alignment requirement.
581
582 4.2.4 Sequences
583
584 Sequences are dynamically-sized arrays. They refer to a a "length"
585 unsigned integer field, which must appear in either the same static scope,
586 prior to the sequence field (in field declaration order), in an upper
587 static scope, or in an upper dynamic scope (see Section 7.3.2). This
588 length field represents the number of elements in the sequence. The
589 sequence per se is an array of "inner type" elements.
590
591 TSDL meta-data representation for a sequence type definition:
592
593 struct {
594 unsigned int length_field;
595 typedef elem_type typename[length_field];
596 typename seq_field_name;
597 }
598
599 A sequence can also be declared as a field type, e.g.:
600
601 struct {
602 unsigned int length_field;
603 long seq_field_name[length_field];
604 }
605
606 Multiple sequences can refer to the same length field, and these length
607 fields can be in a different upper dynamic scope:
608
609 e.g., assuming the stream.event.header defines:
610
611 stream {
612 ...
613 id = 1;
614 event.header := struct {
615 uint16_t seq_len;
616 };
617 };
618
619 event {
620 ...
621 stream_id = 1;
622 fields := struct {
623 long seq_a[stream.event.header.seq_len];
624 char seq_b[stream.event.header.seq_len];
625 };
626 };
627
628 The sequence elements follow the "array" specifications.
629
630 4.2.5 Strings
631
632 Strings are an array of bytes of variable size and are terminated by a '\0'
633 "NULL" character. Their encoding is described in the TSDL meta-data. In
634 absence of encoding attribute information, the default encoding is
635 UTF-8.
636
637 TSDL meta-data representation of a named string type:
638
639 typealias string {
640 encoding = UTF8 OR ASCII;
641 } := name;
642
643 A nameless string type can be declared as a field type:
644
645 string field_name; /* Use default UTF8 encoding */
646
647 Strings are always aligned on byte size.
648
649 5. Event Packet Header
650
651 The event packet header consists of two parts: the "event packet header"
652 is the same for all streams of a trace. The second part, the "event
653 packet context", is described on a per-stream basis. Both are described
654 in the TSDL meta-data. The packets are aligned on architecture-page-sized
655 addresses.
656
657 Event packet header (all fields are optional, specified by TSDL meta-data):
658
659 - Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
660 CTF packet. This magic number is optional, but when present, it should
661 come at the very beginning of the packet.
662 - Trace UUID, used to ensure the event packet match the meta-data used.
663 (note: we cannot use a meta-data checksum in every cases instead of a
664 UUID because meta-data can be appended to while tracing is active)
665 This field is optional.
666 - Stream ID, used as reference to stream description in meta-data.
667 This field is optional if there is only one stream description in the
668 meta-data, but becomes required if there are more than one stream in
669 the TSDL meta-data description.
670
671 Event packet context (all fields are optional, specified by TSDL meta-data):
672
673 - Event packet content size (in bits).
674 - Event packet size (in bits, includes padding).
675 - Event packet content checksum. Checksum excludes the event packet
676 header.
677 - Per-stream event packet sequence count (to deal with UDP packet loss). The
678 number of significant sequence counter bits should also be present, so
679 wrap-arounds are dealt with correctly.
680 - Time-stamp at the beginning and time-stamp at the end of the event packet.
681 Both timestamps are written in the packet header, but sampled respectively
682 while (or before) writing the first event and while (or after) writing the
683 last event in the packet. The inclusive range between these timestamps should
684 include all event timestamps assigned to events contained within the packet.
685 - Events discarded count
686 - Snapshot of a per-stream free-running counter, counting the number of
687 events discarded that were supposed to be written in the stream prior to
688 the first event in the event packet.
689 * Note: producer-consumer buffer full condition should fill the current
690 event packet with padding so we know exactly where events have been
691 discarded.
692 - Lossless compression scheme used for the event packet content. Applied
693 directly to raw data. New types of compression can be added in following
694 versions of the format.
695 0: no compression scheme
696 1: bzip2
697 2: gzip
698 3: xz
699 - Cypher used for the event packet content. Applied after compression.
700 0: no encryption
701 1: AES
702 - Checksum scheme used for the event packet content. Applied after encryption.
703 0: no checksum
704 1: md5
705 2: sha1
706 3: crc32
707
708 5.1 Event Packet Header Description
709
710 The event packet header layout is indicated by the trace packet.header
711 field. Here is a recommended structure type for the packet header with
712 the fields typically expected (although these fields are each optional):
713
714 struct event_packet_header {
715 uint32_t magic;
716 uint8_t uuid[16];
717 uint32_t stream_id;
718 };
719
720 trace {
721 ...
722 packet.header := struct event_packet_header;
723 };
724
725 If the magic number is not present, tools such as "file" will have no
726 mean to discover the file type.
727
728 If the uuid is not present, no validation that the meta-data actually
729 corresponds to the stream is performed.
730
731 If the stream_id packet header field is missing, the trace can only
732 contain a single stream. Its "id" field can be left out, and its events
733 don't need to declare a "stream_id" field.
734
735
736 5.2 Event Packet Context Description
737
738 Event packet context example. These are declared within the stream declaration
739 in the meta-data. All these fields are optional. If the packet size field is
740 missing, the whole stream only contains a single packet. If the content
741 size field is missing, the packet is filled (no padding). The content
742 and packet sizes include all headers.
743
744 An example event packet context type:
745
746 struct event_packet_context {
747 uint64_t timestamp_begin;
748 uint64_t timestamp_end;
749 uint32_t checksum;
750 uint32_t stream_packet_count;
751 uint32_t events_discarded;
752 uint32_t cpu_id;
753 uint32_t/uint16_t content_size;
754 uint32_t/uint16_t packet_size;
755 uint8_t stream_packet_count_bits; /* Significant counter bits */
756 uint8_t compression_scheme;
757 uint8_t encryption_scheme;
758 uint8_t checksum_scheme;
759 };
760
761
762 6. Event Structure
763
764 The overall structure of an event is:
765
766 1 - Stream Packet Context (as specified by the stream meta-data)
767 2 - Event Header (as specified by the stream meta-data)
768 3 - Stream Event Context (as specified by the stream meta-data)
769 4 - Event Context (as specified by the event meta-data)
770 5 - Event Payload (as specified by the event meta-data)
771
772 This structure defines an implicit dynamic scoping, where variants
773 located in inner structures (those with a higher number in the listing
774 above) can refer to the fields of outer structures (with lower number in
775 the listing above). See Section 7.3 TSDL Scopes for more detail.
776
777 6.1 Event Header
778
779 Event headers can be described within the meta-data. We hereby propose, as an
780 example, two types of events headers. Type 1 accommodates streams with less than
781 31 event IDs. Type 2 accommodates streams with 31 or more event IDs.
782
783 One major factor can vary between streams: the number of event IDs assigned to
784 a stream. Luckily, this information tends to stay relatively constant (modulo
785 event registration while trace is being recorded), so we can specify different
786 representations for streams containing few event IDs and streams containing
787 many event IDs, so we end up representing the event ID and time-stamp as
788 densely as possible in each case.
789
790 The header is extended in the rare occasions where the information cannot be
791 represented in the ranges available in the standard event header. They are also
792 used in the rare occasions where the data required for a field could not be
793 collected: the flag corresponding to the missing field within the missing_fields
794 array is then set to 1.
795
796 Types uintX_t represent an X-bit unsigned integer, as declared with
797 either:
798
799 typealias integer { size = X; align = X; signed = false } := uintX_t;
800
801 or
802
803 typealias integer { size = X; align = 1; signed = false } := uintX_t;
804
805 6.1.1 Type 1 - Few event IDs
806
807 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
808 preference).
809 - Native architecture byte ordering.
810 - For "compact" selection
811 - Fixed size: 32 bits.
812 - For "extended" selection
813 - Size depends on the architecture and variant alignment.
814
815 struct event_header_1 {
816 /*
817 * id: range: 0 - 30.
818 * id 31 is reserved to indicate an extended header.
819 */
820 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
821 variant <id> {
822 struct {
823 uint27_t timestamp;
824 } compact;
825 struct {
826 uint32_t id; /* 32-bit event IDs */
827 uint64_t timestamp; /* 64-bit timestamps */
828 } extended;
829 } v;
830 } align(32); /* or align(8) */
831
832
833 6.1.2 Type 2 - Many event IDs
834
835 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
836 preference).
837 - Native architecture byte ordering.
838 - For "compact" selection
839 - Size depends on the architecture and variant alignment.
840 - For "extended" selection
841 - Size depends on the architecture and variant alignment.
842
843 struct event_header_2 {
844 /*
845 * id: range: 0 - 65534.
846 * id 65535 is reserved to indicate an extended header.
847 */
848 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
849 variant <id> {
850 struct {
851 uint32_t timestamp;
852 } compact;
853 struct {
854 uint32_t id; /* 32-bit event IDs */
855 uint64_t timestamp; /* 64-bit timestamps */
856 } extended;
857 } v;
858 } align(16); /* or align(8) */
859
860
861 6.2 Event Context
862
863 The event context contains information relative to the current event.
864 The choice and meaning of this information is specified by the TSDL
865 stream and event meta-data descriptions. The stream context is applied
866 to all events within the stream. The stream context structure follows
867 the event header. The event context is applied to specific events. Its
868 structure follows the stream context structure.
869
870 An example of stream-level event context is to save the event payload size with
871 each event, or to save the current PID with each event. These are declared
872 within the stream declaration within the meta-data:
873
874 stream {
875 ...
876 event.context := struct {
877 uint pid;
878 uint16_t payload_size;
879 };
880 };
881
882 An example of event-specific event context is to declare a bitmap of missing
883 fields, only appended after the stream event context if the extended event
884 header is selected. NR_FIELDS is the number of fields within the event (a
885 numeric value).
886
887 event {
888 context = struct {
889 variant <id> {
890 struct { } compact;
891 struct {
892 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
893 } extended;
894 } v;
895 };
896 ...
897 }
898
899 6.3 Event Payload
900
901 An event payload contains fields specific to a given event type. The fields
902 belonging to an event type are described in the event-specific meta-data
903 within a structure type.
904
905 6.3.1 Padding
906
907 No padding at the end of the event payload. This differs from the ISO/C standard
908 for structures, but follows the CTF standard for structures. In a trace, even
909 though it makes sense to align the beginning of a structure, it really makes no
910 sense to add padding at the end of the structure, because structures are usually
911 not followed by a structure of the same type.
912
913 This trick can be done by adding a zero-length "end" field at the end of the C
914 structures, and by using the offset of this field rather than using sizeof()
915 when calculating the size of a structure (see Appendix "A. Helper macros").
916
917 6.3.2 Alignment
918
919 The event payload is aligned on the largest alignment required by types
920 contained within the payload. (This follows the ISO/C standard for structures)
921
922
923 7. Trace Stream Description Language (TSDL)
924
925 The Trace Stream Description Language (TSDL) allows expression of the
926 binary trace streams layout in a C99-like Domain Specific Language
927 (DSL).
928
929
930 7.1 Meta-data
931
932 The trace stream layout description is located in the trace meta-data.
933 The meta-data is itself located in a stream identified by its name:
934 "metadata".
935
936 The meta-data description can be expressed in two different formats:
937 text-only and packet-based. The text-only description facilitates
938 generation of meta-data and provides a convenient way to enter the
939 meta-data information by hand. The packet-based meta-data provides the
940 CTF stream packet facilities (checksumming, compression, encryption,
941 network-readiness) for meta-data stream generated and transported by a
942 tracer.
943
944 The text-only meta-data file is a plain-text TSDL description. This file
945 must begin with the following characters to identify the file as a CTF
946 TSDL text-based metadata file (without the double-quotes) :
947
948 "/* CTF"
949
950 It must be followed by a space, and the version of the specification
951 followed by the CTF trace, e.g.:
952
953 " 1.8"
954
955 These characters allow automated discovery of file type and CTF
956 specification version. They are interpreted as a the beginning of a
957 comment by the TSDL metadata parser. The comment can be continued to
958 contain extra commented characters before it is closed.
959
960 The packet-based meta-data is made of "meta-data packets", which each
961 start with a meta-data packet header. The packet-based meta-data
962 description is detected by reading the magic number "0x75D11D57" at the
963 beginning of the file. This magic number is also used to detect the
964 endianness of the architecture by trying to read the CTF magic number
965 and its counterpart in reversed endianness. The events within the
966 meta-data stream have no event header nor event context. Each event only
967 contains a "sequence" payload, which is a sequence of bits using the
968 "trace.packet.header.content_size" field as a placeholder for its length
969 (the packet header size should be substracted). The formatting of this
970 sequence of bits is a plain-text representation of the TSDL description.
971 Each meta-data packet start with a special packet header, specific to
972 the meta-data stream, which contains, exactly:
973
974 struct metadata_packet_header {
975 uint32_t magic; /* 0x75D11D57 */
976 uint8_t uuid[16]; /* Unique Universal Identifier */
977 uint32_t checksum; /* 0 if unused */
978 uint32_t content_size; /* in bits */
979 uint32_t packet_size; /* in bits */
980 uint8_t compression_scheme; /* 0 if unused */
981 uint8_t encryption_scheme; /* 0 if unused */
982 uint8_t checksum_scheme; /* 0 if unused */
983 uint8_t major; /* CTF spec version major number */
984 uint8_t minor; /* CTF spec version minor number */
985 };
986
987 The packet-based meta-data can be converted to a text-only meta-data by
988 concatenating all the strings in contains.
989
990 In the textual representation of the meta-data, the text contained
991 within "/*" and "*/", as well as within "//" and end of line, are
992 treated as comments. Boolean values can be represented as true, TRUE,
993 or 1 for true, and false, FALSE, or 0 for false. Within the string-based
994 meta-data description, the trace UUID is represented as a string of
995 hexadecimal digits and dashes "-". In the event packet header, the trace
996 UUID is represented as an array of bytes.
997
998
999 7.2 Declaration vs Definition
1000
1001 A declaration associates a layout to a type, without specifying where
1002 this type is located in the event structure hierarchy (see Section 6).
1003 This therefore includes typedef, typealias, as well as all type
1004 specifiers. In certain circumstances (typedef, structure field and
1005 variant field), a declaration is followed by a declarator, which specify
1006 the newly defined type name (for typedef), or the field name (for
1007 declarations located within structure and variants). Array and sequence,
1008 declared with square brackets ("[" "]"), are part of the declarator,
1009 similarly to C99. The enumeration base type is specified by
1010 ": enum_base", which is part of the type specifier. The variant tag
1011 name, specified between "<" ">", is also part of the type specifier.
1012
1013 A definition associates a type to a location in the event structure
1014 hierarchy (see Section 6). This association is denoted by ":=", as shown
1015 in Section 7.3.
1016
1017
1018 7.3 TSDL Scopes
1019
1020 TSDL uses three different types of scoping: a lexical scope is used for
1021 declarations and type definitions, and static and dynamic scopes are
1022 used for variants references to tag fields (with relative and absolute
1023 path lookups) and for sequence references to length fields.
1024
1025 7.3.1 Lexical Scope
1026
1027 Each of "trace", "stream", "event", "struct" and "variant" have their own
1028 nestable declaration scope, within which types can be declared using "typedef"
1029 and "typealias". A root declaration scope also contains all declarations
1030 located outside of any of the aforementioned declarations. An inner
1031 declaration scope can refer to type declared within its container
1032 lexical scope prior to the inner declaration scope. Redefinition of a
1033 typedef or typealias is not valid, although hiding an upper scope
1034 typedef or typealias is allowed within a sub-scope.
1035
1036 7.3.2 Static and Dynamic Scopes
1037
1038 A local static scope consists in the scope generated by the declaration
1039 of fields within a compound type. A static scope is a local static scope
1040 augmented with the nested sub-static-scopes it contains.
1041
1042 A dynamic scope consists in the static scope augmented with the
1043 implicit event structure definition hierarchy presented at Section 6.
1044
1045 Multiple declarations of the same field name within a local static scope
1046 is not valid. It is however valid to re-use the same field name in
1047 different local scopes.
1048
1049 Nested static and dynamic scopes form lookup paths. These are used for
1050 variant tag and sequence length references. They are used at the variant
1051 and sequence definition site to look up the location of the tag field
1052 associated with a variant, and to lookup up the location of the length
1053 field associated with a sequence.
1054
1055 Variants and sequences can refer to a tag field either using a relative
1056 path or an absolute path. The relative path is relative to the scope in
1057 which the variant or sequence performing the lookup is located.
1058 Relative paths are only allowed to lookup within the same static scope,
1059 which includes its nested static scopes. Lookups targeting parent static
1060 scopes need to be performed with an absolute path.
1061
1062 Absolute path lookups use the full path including the dynamic scope
1063 followed by a "." and then the static scope. Therefore, variants (or
1064 sequences) in lower levels in the dynamic scope (e.g. event context) can
1065 refer to a tag (or length) field located in upper levels (e.g. in the
1066 event header) by specifying, in this case, the associated tag with
1067 <stream.event.header.field_name>. This allows, for instance, the event
1068 context to define a variant referring to the "id" field of the event
1069 header as selector.
1070
1071 The dynamic scope prefixes are thus:
1072
1073 - Trace Packet Header: <trace.packet.header. >,
1074 - Stream Packet Context: <stream.packet.context. >,
1075 - Event Header: <stream.event.header. >,
1076 - Stream Event Context: <stream.event.context. >,
1077 - Event Context: <event.context. >,
1078 - Event Payload: <event.fields. >.
1079
1080
1081 The target dynamic scope must be specified explicitly when referring to
1082 a field outside of the static scope (absolute scope reference). No
1083 conflict can occur between relative and dynamic paths, because the
1084 keywords "trace", "stream", and "event" are reserved, and thus
1085 not permitted as field names. It is recommended that field names
1086 clashing with CTF and C99 reserved keywords use an underscore prefix to
1087 eliminate the risk of generating a description containing an invalid
1088 field name.
1089
1090 The information available in the dynamic scopes can be thought of as the
1091 current tracing context. At trace production, information about the
1092 current context is saved into the specified scope field levels. At trace
1093 consumption, for each event, the current trace context is therefore
1094 readable by accessing the upper dynamic scopes.
1095
1096
1097 7.4 TSDL Examples
1098
1099 The grammar representing the TSDL meta-data is presented in Appendix C.
1100 TSDL Grammar. This section presents a rather lighter reading that
1101 consists in examples of TSDL meta-data, with template values.
1102
1103 The stream "id" can be left out if there is only one stream in the
1104 trace. The event "id" field can be left out if there is only one event
1105 in a stream.
1106
1107 trace {
1108 major = value; /* Trace format version */
1109 minor = value;
1110 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
1111 byte_order = be OR le; /* Endianness (required) */
1112 packet.header := struct {
1113 uint32_t magic;
1114 uint8_t uuid[16];
1115 uint32_t stream_id;
1116 };
1117 };
1118
1119 stream {
1120 id = stream_id;
1121 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
1122 event.header := event_header_1 OR event_header_2;
1123 event.context := struct {
1124 ...
1125 };
1126 packet.context := struct {
1127 ...
1128 };
1129 };
1130
1131 event {
1132 name = "event_name";
1133 id = value; /* Numeric identifier within the stream */
1134 stream_id = stream_id;
1135 loglevel.identifier = "loglevel_identifier";
1136 loglevel.value = value;
1137 context := struct {
1138 ...
1139 };
1140 fields := struct {
1141 ...
1142 };
1143 };
1144
1145 /* More detail on types in section 4. Types */
1146
1147 /*
1148 * Named types:
1149 *
1150 * Type declarations behave similarly to the C standard.
1151 */
1152
1153 typedef aliased_type_specifiers new_type_declarators;
1154
1155 /* e.g.: typedef struct example new_type_name[10]; */
1156
1157 /*
1158 * typealias
1159 *
1160 * The "typealias" declaration can be used to give a name (including
1161 * pointer declarator specifier) to a type. It should also be used to
1162 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1163 * Typealias is a superset of "typedef": it also allows assignment of a
1164 * simple variable identifier to a type.
1165 */
1166
1167 typealias type_class {
1168 ...
1169 } := type_specifiers type_declarator;
1170
1171 /*
1172 * e.g.:
1173 * typealias integer {
1174 * size = 32;
1175 * align = 32;
1176 * signed = false;
1177 * } := struct page *;
1178 *
1179 * typealias integer {
1180 * size = 32;
1181 * align = 32;
1182 * signed = true;
1183 * } := int;
1184 */
1185
1186 struct name {
1187 ...
1188 };
1189
1190 variant name {
1191 ...
1192 };
1193
1194 enum name : integer_type {
1195 ...
1196 };
1197
1198
1199 /*
1200 * Unnamed types, contained within compound type fields, typedef or typealias.
1201 */
1202
1203 struct {
1204 ...
1205 }
1206
1207 struct {
1208 ...
1209 } align(value)
1210
1211 variant {
1212 ...
1213 }
1214
1215 enum : integer_type {
1216 ...
1217 }
1218
1219 typedef type new_type[length];
1220
1221 struct {
1222 type field_name[length];
1223 }
1224
1225 typedef type new_type[length_type];
1226
1227 struct {
1228 type field_name[length_type];
1229 }
1230
1231 integer {
1232 ...
1233 }
1234
1235 floating_point {
1236 ...
1237 }
1238
1239 struct {
1240 integer_type field_name:size; /* GNU/C bitfield */
1241 }
1242
1243 struct {
1244 string field_name;
1245 }
1246
1247
1248 A. Helper macros
1249
1250 The two following macros keep track of the size of a GNU/C structure without
1251 padding at the end by placing HEADER_END as the last field. A one byte end field
1252 is used for C90 compatibility (C99 flexible arrays could be used here). Note
1253 that this does not affect the effective structure size, which should always be
1254 calculated with the header_sizeof() helper.
1255
1256 #define HEADER_END char end_field
1257 #define header_sizeof(type) offsetof(typeof(type), end_field)
1258
1259
1260 B. Stream Header Rationale
1261
1262 An event stream is divided in contiguous event packets of variable size. These
1263 subdivisions allow the trace analyzer to perform a fast binary search by time
1264 within the stream (typically requiring to index only the event packet headers)
1265 without reading the whole stream. These subdivisions have a variable size to
1266 eliminate the need to transfer the event packet padding when partially filled
1267 event packets must be sent when streaming a trace for live viewing/analysis.
1268 An event packet can contain a certain amount of padding at the end. Dividing
1269 streams into event packets is also useful for network streaming over UDP and
1270 flight recorder mode tracing (a whole event packet can be swapped out of the
1271 buffer atomically for reading).
1272
1273 The stream header is repeated at the beginning of each event packet to allow
1274 flexibility in terms of:
1275
1276 - streaming support,
1277 - allowing arbitrary buffers to be discarded without making the trace
1278 unreadable,
1279 - allow UDP packet loss handling by either dealing with missing event packet
1280 or asking for re-transmission.
1281 - transparently support flight recorder mode,
1282 - transparently support crash dump.
1283
1284
1285 C. TSDL Grammar
1286
1287 /*
1288 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
1289 *
1290 * Inspired from the C99 grammar:
1291 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
1292 * and c++1x grammar (draft)
1293 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
1294 *
1295 * Specialized for CTF needs by including only constant and declarations from
1296 * C99 (excluding function declarations), and by adding support for variants,
1297 * sequences and CTF-specific specifiers. Enumeration container types
1298 * semantic is inspired from c++1x enum-base.
1299 */
1300
1301 1) Lexical grammar
1302
1303 1.1) Lexical elements
1304
1305 token:
1306 keyword
1307 identifier
1308 constant
1309 string-literal
1310 punctuator
1311
1312 1.2) Keywords
1313
1314 keyword: is one of
1315
1316 align
1317 const
1318 char
1319 double
1320 enum
1321 event
1322 floating_point
1323 float
1324 integer
1325 int
1326 long
1327 short
1328 signed
1329 stream
1330 string
1331 struct
1332 trace
1333 typealias
1334 typedef
1335 unsigned
1336 variant
1337 void
1338 _Bool
1339 _Complex
1340 _Imaginary
1341
1342
1343 1.3) Identifiers
1344
1345 identifier:
1346 identifier-nondigit
1347 identifier identifier-nondigit
1348 identifier digit
1349
1350 identifier-nondigit:
1351 nondigit
1352 universal-character-name
1353 any other implementation-defined characters
1354
1355 nondigit:
1356 _
1357 [a-zA-Z] /* regular expression */
1358
1359 digit:
1360 [0-9] /* regular expression */
1361
1362 1.4) Universal character names
1363
1364 universal-character-name:
1365 \u hex-quad
1366 \U hex-quad hex-quad
1367
1368 hex-quad:
1369 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1370
1371 1.5) Constants
1372
1373 constant:
1374 integer-constant
1375 enumeration-constant
1376 character-constant
1377
1378 integer-constant:
1379 decimal-constant integer-suffix-opt
1380 octal-constant integer-suffix-opt
1381 hexadecimal-constant integer-suffix-opt
1382
1383 decimal-constant:
1384 nonzero-digit
1385 decimal-constant digit
1386
1387 octal-constant:
1388 0
1389 octal-constant octal-digit
1390
1391 hexadecimal-constant:
1392 hexadecimal-prefix hexadecimal-digit
1393 hexadecimal-constant hexadecimal-digit
1394
1395 hexadecimal-prefix:
1396 0x
1397 0X
1398
1399 nonzero-digit:
1400 [1-9]
1401
1402 integer-suffix:
1403 unsigned-suffix long-suffix-opt
1404 unsigned-suffix long-long-suffix
1405 long-suffix unsigned-suffix-opt
1406 long-long-suffix unsigned-suffix-opt
1407
1408 unsigned-suffix:
1409 u
1410 U
1411
1412 long-suffix:
1413 l
1414 L
1415
1416 long-long-suffix:
1417 ll
1418 LL
1419
1420 enumeration-constant:
1421 identifier
1422 string-literal
1423
1424 character-constant:
1425 ' c-char-sequence '
1426 L' c-char-sequence '
1427
1428 c-char-sequence:
1429 c-char
1430 c-char-sequence c-char
1431
1432 c-char:
1433 any member of source charset except single-quote ('), backslash
1434 (\), or new-line character.
1435 escape-sequence
1436
1437 escape-sequence:
1438 simple-escape-sequence
1439 octal-escape-sequence
1440 hexadecimal-escape-sequence
1441 universal-character-name
1442
1443 simple-escape-sequence: one of
1444 \' \" \? \\ \a \b \f \n \r \t \v
1445
1446 octal-escape-sequence:
1447 \ octal-digit
1448 \ octal-digit octal-digit
1449 \ octal-digit octal-digit octal-digit
1450
1451 hexadecimal-escape-sequence:
1452 \x hexadecimal-digit
1453 hexadecimal-escape-sequence hexadecimal-digit
1454
1455 1.6) String literals
1456
1457 string-literal:
1458 " s-char-sequence-opt "
1459 L" s-char-sequence-opt "
1460
1461 s-char-sequence:
1462 s-char
1463 s-char-sequence s-char
1464
1465 s-char:
1466 any member of source charset except double-quote ("), backslash
1467 (\), or new-line character.
1468 escape-sequence
1469
1470 1.7) Punctuators
1471
1472 punctuator: one of
1473 [ ] ( ) { } . -> * + - < > : ; ... = ,
1474
1475
1476 2) Phrase structure grammar
1477
1478 primary-expression:
1479 identifier
1480 constant
1481 string-literal
1482 ( unary-expression )
1483
1484 postfix-expression:
1485 primary-expression
1486 postfix-expression [ unary-expression ]
1487 postfix-expression . identifier
1488 postfix-expressoin -> identifier
1489
1490 unary-expression:
1491 postfix-expression
1492 unary-operator postfix-expression
1493
1494 unary-operator: one of
1495 + -
1496
1497 assignment-operator:
1498 =
1499
1500 type-assignment-operator:
1501 :=
1502
1503 constant-expression-range:
1504 unary-expression ... unary-expression
1505
1506 2.2) Declarations:
1507
1508 declaration:
1509 declaration-specifiers declarator-list-opt ;
1510 ctf-specifier ;
1511
1512 declaration-specifiers:
1513 storage-class-specifier declaration-specifiers-opt
1514 type-specifier declaration-specifiers-opt
1515 type-qualifier declaration-specifiers-opt
1516
1517 declarator-list:
1518 declarator
1519 declarator-list , declarator
1520
1521 abstract-declarator-list:
1522 abstract-declarator
1523 abstract-declarator-list , abstract-declarator
1524
1525 storage-class-specifier:
1526 typedef
1527
1528 type-specifier:
1529 void
1530 char
1531 short
1532 int
1533 long
1534 float
1535 double
1536 signed
1537 unsigned
1538 _Bool
1539 _Complex
1540 _Imaginary
1541 struct-specifier
1542 variant-specifier
1543 enum-specifier
1544 typedef-name
1545 ctf-type-specifier
1546
1547 align-attribute:
1548 align ( unary-expression )
1549
1550 struct-specifier:
1551 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1552 struct identifier align-attribute-opt
1553
1554 struct-or-variant-declaration-list:
1555 struct-or-variant-declaration
1556 struct-or-variant-declaration-list struct-or-variant-declaration
1557
1558 struct-or-variant-declaration:
1559 specifier-qualifier-list struct-or-variant-declarator-list ;
1560 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
1561 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1562 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
1563
1564 specifier-qualifier-list:
1565 type-specifier specifier-qualifier-list-opt
1566 type-qualifier specifier-qualifier-list-opt
1567
1568 struct-or-variant-declarator-list:
1569 struct-or-variant-declarator
1570 struct-or-variant-declarator-list , struct-or-variant-declarator
1571
1572 struct-or-variant-declarator:
1573 declarator
1574 declarator-opt : unary-expression
1575
1576 variant-specifier:
1577 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1578 variant identifier variant-tag
1579
1580 variant-tag:
1581 < unary-expression >
1582
1583 enum-specifier:
1584 enum identifier-opt { enumerator-list }
1585 enum identifier-opt { enumerator-list , }
1586 enum identifier
1587 enum identifier-opt : declaration-specifiers { enumerator-list }
1588 enum identifier-opt : declaration-specifiers { enumerator-list , }
1589
1590 enumerator-list:
1591 enumerator
1592 enumerator-list , enumerator
1593
1594 enumerator:
1595 enumeration-constant
1596 enumeration-constant assignment-operator unary-expression
1597 enumeration-constant assignment-operator constant-expression-range
1598
1599 type-qualifier:
1600 const
1601
1602 declarator:
1603 pointer-opt direct-declarator
1604
1605 direct-declarator:
1606 identifier
1607 ( declarator )
1608 direct-declarator [ unary-expression ]
1609
1610 abstract-declarator:
1611 pointer-opt direct-abstract-declarator
1612
1613 direct-abstract-declarator:
1614 identifier-opt
1615 ( abstract-declarator )
1616 direct-abstract-declarator [ unary-expression ]
1617 direct-abstract-declarator [ ]
1618
1619 pointer:
1620 * type-qualifier-list-opt
1621 * type-qualifier-list-opt pointer
1622
1623 type-qualifier-list:
1624 type-qualifier
1625 type-qualifier-list type-qualifier
1626
1627 typedef-name:
1628 identifier
1629
1630 2.3) CTF-specific declarations
1631
1632 ctf-specifier:
1633 event { ctf-assignment-expression-list-opt }
1634 stream { ctf-assignment-expression-list-opt }
1635 trace { ctf-assignment-expression-list-opt }
1636 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1637 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
1638
1639 ctf-type-specifier:
1640 floating_point { ctf-assignment-expression-list-opt }
1641 integer { ctf-assignment-expression-list-opt }
1642 string { ctf-assignment-expression-list-opt }
1643 string
1644
1645 ctf-assignment-expression-list:
1646 ctf-assignment-expression ;
1647 ctf-assignment-expression-list ctf-assignment-expression ;
1648
1649 ctf-assignment-expression:
1650 unary-expression assignment-operator unary-expression
1651 unary-expression type-assignment-operator type-specifier
1652 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
1653 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1654 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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