Update text-based metadata header: "/* TSDL" is sufficient
[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 possess a
419 field name, which is a unique identifier within the structure.
420
421 A nameless structure can be declared as a field type or as part of a typedef:
422
423 struct {
424 ...
425 }
426
427 Alignment for a structure compound type can be forced to a minimum value
428 by adding an "align" specifier after the declaration of a structure
429 body. This attribute is read as: align(value). The value is specified in
430 bits. The structure will be aligned on the maximum value between this
431 attribute and the alignment required by the basic types contained within
432 the structure. e.g.
433
434 struct {
435 ...
436 } align(32)
437
438 4.2.2 Variants (Discriminated/Tagged Unions)
439
440 A CTF variant is a selection between different types. A CTF variant must
441 always be defined within the scope of a structure or within fields
442 contained within a structure (defined recursively). A "tag" enumeration
443 field must appear in either the same static scope, prior to the variant
444 field (in field declaration order), in an upper static scope , or in an
445 upper dynamic scope (see Section 7.3.2). The type selection is indicated
446 by the mapping from the enumeration value to the string used as variant
447 type selector. The field to use as tag is specified by the "tag_field",
448 specified between "< >" after the "variant" keyword for unnamed
449 variants, and after "variant name" for named variants.
450
451 The alignment of the variant is the alignment of the type as selected by the tag
452 value for the specific instance of the variant. The alignment of the type
453 containing the variant is independent of the variant alignment. The size of the
454 variant is the size as selected by the tag value for the specific instance of
455 the variant.
456
457 A named variant declaration followed by its definition within a structure
458 declaration:
459
460 variant name {
461 field_type sel1;
462 field_type sel2;
463 field_type sel3;
464 ...
465 };
466
467 struct {
468 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
469 ...
470 variant name <tag_field> v;
471 }
472
473 An unnamed variant definition within a structure is expressed by the following
474 TSDL meta-data:
475
476 struct {
477 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
478 ...
479 variant <tag_field> {
480 field_type sel1;
481 field_type sel2;
482 field_type sel3;
483 ...
484 } v;
485 }
486
487 Example of a named variant within a sequence that refers to a single tag field:
488
489 variant example {
490 uint32_t a;
491 uint64_t b;
492 short c;
493 };
494
495 struct {
496 enum : uint2_t { a, b, c } choice;
497 unsigned int seqlen;
498 variant example <choice> v[seqlen];
499 }
500
501 Example of an unnamed variant:
502
503 struct {
504 enum : uint2_t { a, b, c, d } choice;
505 /* Unrelated fields can be added between the variant and its tag */
506 int32_t somevalue;
507 variant <choice> {
508 uint32_t a;
509 uint64_t b;
510 short c;
511 struct {
512 unsigned int field1;
513 uint64_t field2;
514 } d;
515 } s;
516 }
517
518 Example of an unnamed variant within an array:
519
520 struct {
521 enum : uint2_t { a, b, c } choice;
522 variant <choice> {
523 uint32_t a;
524 uint64_t b;
525 short c;
526 } v[10];
527 }
528
529 Example of a variant type definition within a structure, where the defined type
530 is then declared within an array of structures. This variant refers to a tag
531 located in an upper static scope. This example clearly shows that a variant
532 type definition referring to the tag "x" uses the closest preceding field from
533 the static scope of the type definition.
534
535 struct {
536 enum : uint2_t { a, b, c, d } x;
537
538 typedef variant <x> { /*
539 * "x" refers to the preceding "x" enumeration in the
540 * static scope of the type definition.
541 */
542 uint32_t a;
543 uint64_t b;
544 short c;
545 } example_variant;
546
547 struct {
548 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
549 example_variant v; /*
550 * "v" uses the "enum : uint2_t { a, b, c, d }"
551 * tag.
552 */
553 } a[10];
554 }
555
556 4.2.3 Arrays
557
558 Arrays are fixed-length. Their length is declared in the type
559 declaration within the meta-data. They contain an array of "inner type"
560 elements, which can refer to any type not containing the type of the
561 array being declared (no circular dependency). The length is the number
562 of elements in an array.
563
564 TSDL meta-data representation of a named array:
565
566 typedef elem_type name[length];
567
568 A nameless array can be declared as a field type within a structure, e.g.:
569
570 uint8_t field_name[10];
571
572 Arrays are always aligned on their element alignment requirement.
573
574 4.2.4 Sequences
575
576 Sequences are dynamically-sized arrays. They refer to a a "length"
577 unsigned integer field, which must appear in either the same static scope,
578 prior to the sequence field (in field declaration order), in an upper
579 static scope, or in an upper dynamic scope (see Section 7.3.2). This
580 length field represents the number of elements in the sequence. The
581 sequence per se is an array of "inner type" elements.
582
583 TSDL meta-data representation for a sequence type definition:
584
585 struct {
586 unsigned int length_field;
587 typedef elem_type typename[length_field];
588 typename seq_field_name;
589 }
590
591 A sequence can also be declared as a field type, e.g.:
592
593 struct {
594 unsigned int length_field;
595 long seq_field_name[length_field];
596 }
597
598 Multiple sequences can refer to the same length field, and these length
599 fields can be in a different upper dynamic scope:
600
601 e.g., assuming the stream.event.header defines:
602
603 stream {
604 ...
605 id = 1;
606 event.header := struct {
607 uint16_t seq_len;
608 };
609 };
610
611 event {
612 ...
613 stream_id = 1;
614 fields := struct {
615 long seq_a[stream.event.header.seq_len];
616 char seq_b[stream.event.header.seq_len];
617 };
618 };
619
620 The sequence elements follow the "array" specifications.
621
622 4.2.5 Strings
623
624 Strings are an array of bytes of variable size and are terminated by a '\0'
625 "NULL" character. Their encoding is described in the TSDL meta-data. In
626 absence of encoding attribute information, the default encoding is
627 UTF-8.
628
629 TSDL meta-data representation of a named string type:
630
631 typealias string {
632 encoding = UTF8 OR ASCII;
633 } := name;
634
635 A nameless string type can be declared as a field type:
636
637 string field_name; /* Use default UTF8 encoding */
638
639 Strings are always aligned on byte size.
640
641 5. Event Packet Header
642
643 The event packet header consists of two parts: the "event packet header"
644 is the same for all streams of a trace. The second part, the "event
645 packet context", is described on a per-stream basis. Both are described
646 in the TSDL meta-data. The packets are aligned on architecture-page-sized
647 addresses.
648
649 Event packet header (all fields are optional, specified by TSDL meta-data):
650
651 - Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
652 CTF packet. This magic number is optional, but when present, it should
653 come at the very beginning of the packet.
654 - Trace UUID, used to ensure the event packet match the meta-data used.
655 (note: we cannot use a meta-data checksum in every cases instead of a
656 UUID because meta-data can be appended to while tracing is active)
657 This field is optional.
658 - Stream ID, used as reference to stream description in meta-data.
659 This field is optional if there is only one stream description in the
660 meta-data, but becomes required if there are more than one stream in
661 the TSDL meta-data description.
662
663 Event packet context (all fields are optional, specified by TSDL meta-data):
664
665 - Event packet content size (in bits).
666 - Event packet size (in bits, includes padding).
667 - Event packet content checksum. Checksum excludes the event packet
668 header.
669 - Per-stream event packet sequence count (to deal with UDP packet loss). The
670 number of significant sequence counter bits should also be present, so
671 wrap-arounds are dealt with correctly.
672 - Time-stamp at the beginning and time-stamp at the end of the event packet.
673 Both timestamps are written in the packet header, but sampled respectively
674 while (or before) writing the first event and while (or after) writing the
675 last event in the packet. The inclusive range between these timestamps should
676 include all event timestamps assigned to events contained within the packet.
677 - Events discarded count
678 - Snapshot of a per-stream free-running counter, counting the number of
679 events discarded that were supposed to be written in the stream prior to
680 the first event in the event packet.
681 * Note: producer-consumer buffer full condition should fill the current
682 event packet with padding so we know exactly where events have been
683 discarded.
684 - Lossless compression scheme used for the event packet content. Applied
685 directly to raw data. New types of compression can be added in following
686 versions of the format.
687 0: no compression scheme
688 1: bzip2
689 2: gzip
690 3: xz
691 - Cypher used for the event packet content. Applied after compression.
692 0: no encryption
693 1: AES
694 - Checksum scheme used for the event packet content. Applied after encryption.
695 0: no checksum
696 1: md5
697 2: sha1
698 3: crc32
699
700 5.1 Event Packet Header Description
701
702 The event packet header layout is indicated by the trace packet.header
703 field. Here is a recommended structure type for the packet header with
704 the fields typically expected (although these fields are each optional):
705
706 struct event_packet_header {
707 uint32_t magic;
708 uint8_t uuid[16];
709 uint32_t stream_id;
710 };
711
712 trace {
713 ...
714 packet.header := struct event_packet_header;
715 };
716
717 If the magic number is not present, tools such as "file" will have no
718 mean to discover the file type.
719
720 If the uuid is not present, no validation that the meta-data actually
721 corresponds to the stream is performed.
722
723 If the stream_id packet header field is missing, the trace can only
724 contain a single stream. Its "id" field can be left out, and its events
725 don't need to declare a "stream_id" field.
726
727
728 5.2 Event Packet Context Description
729
730 Event packet context example. These are declared within the stream declaration
731 in the meta-data. All these fields are optional. If the packet size field is
732 missing, the whole stream only contains a single packet. If the content
733 size field is missing, the packet is filled (no padding). The content
734 and packet sizes include all headers.
735
736 An example event packet context type:
737
738 struct event_packet_context {
739 uint64_t timestamp_begin;
740 uint64_t timestamp_end;
741 uint32_t checksum;
742 uint32_t stream_packet_count;
743 uint32_t events_discarded;
744 uint32_t cpu_id;
745 uint32_t/uint16_t content_size;
746 uint32_t/uint16_t packet_size;
747 uint8_t stream_packet_count_bits; /* Significant counter bits */
748 uint8_t compression_scheme;
749 uint8_t encryption_scheme;
750 uint8_t checksum_scheme;
751 };
752
753
754 6. Event Structure
755
756 The overall structure of an event is:
757
758 1 - Stream Packet Context (as specified by the stream meta-data)
759 2 - Event Header (as specified by the stream meta-data)
760 3 - Stream Event Context (as specified by the stream meta-data)
761 4 - Event Context (as specified by the event meta-data)
762 5 - Event Payload (as specified by the event meta-data)
763
764 This structure defines an implicit dynamic scoping, where variants
765 located in inner structures (those with a higher number in the listing
766 above) can refer to the fields of outer structures (with lower number in
767 the listing above). See Section 7.3 TSDL Scopes for more detail.
768
769 6.1 Event Header
770
771 Event headers can be described within the meta-data. We hereby propose, as an
772 example, two types of events headers. Type 1 accommodates streams with less than
773 31 event IDs. Type 2 accommodates streams with 31 or more event IDs.
774
775 One major factor can vary between streams: the number of event IDs assigned to
776 a stream. Luckily, this information tends to stay relatively constant (modulo
777 event registration while trace is being recorded), so we can specify different
778 representations for streams containing few event IDs and streams containing
779 many event IDs, so we end up representing the event ID and time-stamp as
780 densely as possible in each case.
781
782 The header is extended in the rare occasions where the information cannot be
783 represented in the ranges available in the standard event header. They are also
784 used in the rare occasions where the data required for a field could not be
785 collected: the flag corresponding to the missing field within the missing_fields
786 array is then set to 1.
787
788 Types uintX_t represent an X-bit unsigned integer, as declared with
789 either:
790
791 typealias integer { size = X; align = X; signed = false } := uintX_t;
792
793 or
794
795 typealias integer { size = X; align = 1; signed = false } := uintX_t;
796
797 6.1.1 Type 1 - Few event IDs
798
799 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
800 preference).
801 - Native architecture byte ordering.
802 - For "compact" selection
803 - Fixed size: 32 bits.
804 - For "extended" selection
805 - Size depends on the architecture and variant alignment.
806
807 struct event_header_1 {
808 /*
809 * id: range: 0 - 30.
810 * id 31 is reserved to indicate an extended header.
811 */
812 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
813 variant <id> {
814 struct {
815 uint27_t timestamp;
816 } compact;
817 struct {
818 uint32_t id; /* 32-bit event IDs */
819 uint64_t timestamp; /* 64-bit timestamps */
820 } extended;
821 } v;
822 } align(32); /* or align(8) */
823
824
825 6.1.2 Type 2 - Many event IDs
826
827 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
828 preference).
829 - Native architecture byte ordering.
830 - For "compact" selection
831 - Size depends on the architecture and variant alignment.
832 - For "extended" selection
833 - Size depends on the architecture and variant alignment.
834
835 struct event_header_2 {
836 /*
837 * id: range: 0 - 65534.
838 * id 65535 is reserved to indicate an extended header.
839 */
840 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
841 variant <id> {
842 struct {
843 uint32_t timestamp;
844 } compact;
845 struct {
846 uint32_t id; /* 32-bit event IDs */
847 uint64_t timestamp; /* 64-bit timestamps */
848 } extended;
849 } v;
850 } align(16); /* or align(8) */
851
852
853 6.2 Event Context
854
855 The event context contains information relative to the current event.
856 The choice and meaning of this information is specified by the TSDL
857 stream and event meta-data descriptions. The stream context is applied
858 to all events within the stream. The stream context structure follows
859 the event header. The event context is applied to specific events. Its
860 structure follows the stream context structure.
861
862 An example of stream-level event context is to save the event payload size with
863 each event, or to save the current PID with each event. These are declared
864 within the stream declaration within the meta-data:
865
866 stream {
867 ...
868 event.context := struct {
869 uint pid;
870 uint16_t payload_size;
871 };
872 };
873
874 An example of event-specific event context is to declare a bitmap of missing
875 fields, only appended after the stream event context if the extended event
876 header is selected. NR_FIELDS is the number of fields within the event (a
877 numeric value).
878
879 event {
880 context = struct {
881 variant <id> {
882 struct { } compact;
883 struct {
884 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
885 } extended;
886 } v;
887 };
888 ...
889 }
890
891 6.3 Event Payload
892
893 An event payload contains fields specific to a given event type. The fields
894 belonging to an event type are described in the event-specific meta-data
895 within a structure type.
896
897 6.3.1 Padding
898
899 No padding at the end of the event payload. This differs from the ISO/C standard
900 for structures, but follows the CTF standard for structures. In a trace, even
901 though it makes sense to align the beginning of a structure, it really makes no
902 sense to add padding at the end of the structure, because structures are usually
903 not followed by a structure of the same type.
904
905 This trick can be done by adding a zero-length "end" field at the end of the C
906 structures, and by using the offset of this field rather than using sizeof()
907 when calculating the size of a structure (see Appendix "A. Helper macros").
908
909 6.3.2 Alignment
910
911 The event payload is aligned on the largest alignment required by types
912 contained within the payload. (This follows the ISO/C standard for structures)
913
914
915 7. Trace Stream Description Language (TSDL)
916
917 The Trace Stream Description Language (TSDL) allows expression of the
918 binary trace streams layout in a C99-like Domain Specific Language
919 (DSL).
920
921
922 7.1 Meta-data
923
924 The trace stream layout description is located in the trace meta-data.
925 The meta-data is itself located in a stream identified by its name:
926 "metadata".
927
928 The meta-data description can be expressed in two different formats:
929 text-only and packet-based. The text-only description facilitates
930 generation of meta-data and provides a convenient way to enter the
931 meta-data information by hand. The packet-based meta-data provides the
932 CTF stream packet facilities (checksumming, compression, encryption,
933 network-readiness) for meta-data stream generated and transported by a
934 tracer.
935
936 The text-only meta-data file is a plain-text TSDL description. This file
937 must begin with the following characters to identify the file as a CTF
938 TSDL text-based metadata file (without the double-quotes) :
939
940 "/* TSDL"
941
942 These characters allow automated discovery of file type. They are
943 interpreted as a the beginning of a comment by the TSDL metadata parser.
944 The comment can be continued to contain extra commented characters
945 before it is closed.
946
947 The packet-based meta-data is made of "meta-data packets", which each
948 start with a meta-data packet header. The packet-based meta-data
949 description is detected by reading the magic number "0x75D11D57" at the
950 beginning of the file. This magic number is also used to detect the
951 endianness of the architecture by trying to read the CTF magic number
952 and its counterpart in reversed endianness. The events within the
953 meta-data stream have no event header nor event context. Each event only
954 contains a "sequence" payload, which is a sequence of bits using the
955 "trace.packet.header.content_size" field as a placeholder for its length
956 (the packet header size should be substracted). The formatting of this
957 sequence of bits is a plain-text representation of the TSDL description.
958 Each meta-data packet start with a special packet header, specific to
959 the meta-data stream, which contains, exactly:
960
961 struct metadata_packet_header {
962 uint32_t magic; /* 0x75D11D57 */
963 uint8_t uuid[16]; /* Unique Universal Identifier */
964 uint32_t checksum; /* 0 if unused */
965 uint32_t content_size; /* in bits */
966 uint32_t packet_size; /* in bits */
967 uint8_t compression_scheme; /* 0 if unused */
968 uint8_t encryption_scheme; /* 0 if unused */
969 uint8_t checksum_scheme; /* 0 if unused */
970 };
971
972 The packet-based meta-data can be converted to a text-only meta-data by
973 concatenating all the strings in contains.
974
975 In the textual representation of the meta-data, the text contained
976 within "/*" and "*/", as well as within "//" and end of line, are
977 treated as comments. Boolean values can be represented as true, TRUE,
978 or 1 for true, and false, FALSE, or 0 for false. Within the string-based
979 meta-data description, the trace UUID is represented as a string of
980 hexadecimal digits and dashes "-". In the event packet header, the trace
981 UUID is represented as an array of bytes.
982
983
984 7.2 Declaration vs Definition
985
986 A declaration associates a layout to a type, without specifying where
987 this type is located in the event structure hierarchy (see Section 6).
988 This therefore includes typedef, typealias, as well as all type
989 specifiers. In certain circumstances (typedef, structure field and
990 variant field), a declaration is followed by a declarator, which specify
991 the newly defined type name (for typedef), or the field name (for
992 declarations located within structure and variants). Array and sequence,
993 declared with square brackets ("[" "]"), are part of the declarator,
994 similarly to C99. The enumeration base type is specified by
995 ": enum_base", which is part of the type specifier. The variant tag
996 name, specified between "<" ">", is also part of the type specifier.
997
998 A definition associates a type to a location in the event structure
999 hierarchy (see Section 6). This association is denoted by ":=", as shown
1000 in Section 7.3.
1001
1002
1003 7.3 TSDL Scopes
1004
1005 TSDL uses three different types of scoping: a lexical scope is used for
1006 declarations and type definitions, and static and dynamic scopes are
1007 used for variants references to tag fields (with relative and absolute
1008 path lookups) and for sequence references to length fields.
1009
1010 7.3.1 Lexical Scope
1011
1012 Each of "trace", "stream", "event", "struct" and "variant" have their own
1013 nestable declaration scope, within which types can be declared using "typedef"
1014 and "typealias". A root declaration scope also contains all declarations
1015 located outside of any of the aforementioned declarations. An inner
1016 declaration scope can refer to type declared within its container
1017 lexical scope prior to the inner declaration scope. Redefinition of a
1018 typedef or typealias is not valid, although hiding an upper scope
1019 typedef or typealias is allowed within a sub-scope.
1020
1021 7.3.2 Static and Dynamic Scopes
1022
1023 A local static scope consists in the scope generated by the declaration
1024 of fields within a compound type. A static scope is a local static scope
1025 augmented with the nested sub-static-scopes it contains.
1026
1027 A dynamic scope consists in the static scope augmented with the
1028 implicit event structure definition hierarchy presented at Section 6.
1029
1030 Multiple declarations of the same field name within a local static scope
1031 is not valid. It is however valid to re-use the same field name in
1032 different local scopes.
1033
1034 Nested static and dynamic scopes form lookup paths. These are used for
1035 variant tag and sequence length references. They are used at the variant
1036 and sequence definition site to look up the location of the tag field
1037 associated with a variant, and to lookup up the location of the length
1038 field associated with a sequence.
1039
1040 Variants and sequences can refer to a tag field either using a relative
1041 path or an absolute path. The relative path starts with "." to ensure
1042 there are no conflicts with dynamic scope names. It is relative to the
1043 scope in which the variant or sequence performing the lookup is located.
1044 Relative paths are only allowed to lookup within the same static scope,
1045 which includes its nested static scopes. Lookups targeting parent static
1046 scopes need to be performed with an absolute path.
1047
1048 Absolute path lookups use the full path including the dynamic scope
1049 followed by a "." and then the static scope. Therefore, variants (or
1050 sequences) in lower levels in the dynamic scope (e.g. event context) can
1051 refer to a tag (or length) field located in upper levels (e.g. in the
1052 event header) by specifying, in this case, the associated tag with
1053 <stream.event.header.field_name>. This allows, for instance, the event
1054 context to define a variant referring to the "id" field of the event
1055 header as selector.
1056
1057 The dynamic scope prefixes are thus:
1058
1059 - Trace Packet Header: <trace.packet.header. >,
1060 - Stream Packet Context: <stream.packet.context. >,
1061 - Event Header: <stream.event.header. >,
1062 - Stream Event Context: <stream.event.context. >,
1063 - Event Context: <event.context. >,
1064 - Event Payload: <event.fields. >.
1065
1066
1067 The target dynamic scope must be specified explicitly when referring to
1068 a field outside of the static scope (absolute scope reference).
1069 References to fields within the static scope (including local static
1070 scopes and nested static scopes) can be referenced by using a relative
1071 reference (starting with ".").
1072
1073 As a matter of convenience, the leading "." in relative paths can be
1074 omitted. In case of conflict between relative and dynamic paths, the
1075 relative path is preferred. It is recommended to use the "." prefix for
1076 relative paths to ensure no path name conflict can occur.
1077
1078 The information available in the dynamic scopes can be thought of as the
1079 current tracing context. At trace production, information about the
1080 current context is saved into the specified scope field levels. At trace
1081 consumption, for each event, the current trace context is therefore
1082 readable by accessing the upper dynamic scopes.
1083
1084
1085 7.4 TSDL Examples
1086
1087 The grammar representing the TSDL meta-data is presented in Appendix C.
1088 TSDL Grammar. This section presents a rather lighter reading that
1089 consists in examples of TSDL meta-data, with template values.
1090
1091 The stream "id" can be left out if there is only one stream in the
1092 trace. The event "id" field can be left out if there is only one event
1093 in a stream.
1094
1095 trace {
1096 major = value; /* Trace format version */
1097 minor = value;
1098 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
1099 byte_order = be OR le; /* Endianness (required) */
1100 packet.header := struct {
1101 uint32_t magic;
1102 uint8_t uuid[16];
1103 uint32_t stream_id;
1104 };
1105 };
1106
1107 stream {
1108 id = stream_id;
1109 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
1110 event.header := event_header_1 OR event_header_2;
1111 event.context := struct {
1112 ...
1113 };
1114 packet.context := struct {
1115 ...
1116 };
1117 };
1118
1119 event {
1120 name = event_name;
1121 id = value; /* Numeric identifier within the stream */
1122 stream_id = stream_id;
1123 context := struct {
1124 ...
1125 };
1126 fields := struct {
1127 ...
1128 };
1129 };
1130
1131 /* More detail on types in section 4. Types */
1132
1133 /*
1134 * Named types:
1135 *
1136 * Type declarations behave similarly to the C standard.
1137 */
1138
1139 typedef aliased_type_specifiers new_type_declarators;
1140
1141 /* e.g.: typedef struct example new_type_name[10]; */
1142
1143 /*
1144 * typealias
1145 *
1146 * The "typealias" declaration can be used to give a name (including
1147 * pointer declarator specifier) to a type. It should also be used to
1148 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1149 * Typealias is a superset of "typedef": it also allows assignment of a
1150 * simple variable identifier to a type.
1151 */
1152
1153 typealias type_class {
1154 ...
1155 } := type_specifiers type_declarator;
1156
1157 /*
1158 * e.g.:
1159 * typealias integer {
1160 * size = 32;
1161 * align = 32;
1162 * signed = false;
1163 * } := struct page *;
1164 *
1165 * typealias integer {
1166 * size = 32;
1167 * align = 32;
1168 * signed = true;
1169 * } := int;
1170 */
1171
1172 struct name {
1173 ...
1174 };
1175
1176 variant name {
1177 ...
1178 };
1179
1180 enum name : integer_type {
1181 ...
1182 };
1183
1184
1185 /*
1186 * Unnamed types, contained within compound type fields, typedef or typealias.
1187 */
1188
1189 struct {
1190 ...
1191 }
1192
1193 struct {
1194 ...
1195 } align(value)
1196
1197 variant {
1198 ...
1199 }
1200
1201 enum : integer_type {
1202 ...
1203 }
1204
1205 typedef type new_type[length];
1206
1207 struct {
1208 type field_name[length];
1209 }
1210
1211 typedef type new_type[length_type];
1212
1213 struct {
1214 type field_name[length_type];
1215 }
1216
1217 integer {
1218 ...
1219 }
1220
1221 floating_point {
1222 ...
1223 }
1224
1225 struct {
1226 integer_type field_name:size; /* GNU/C bitfield */
1227 }
1228
1229 struct {
1230 string field_name;
1231 }
1232
1233
1234 A. Helper macros
1235
1236 The two following macros keep track of the size of a GNU/C structure without
1237 padding at the end by placing HEADER_END as the last field. A one byte end field
1238 is used for C90 compatibility (C99 flexible arrays could be used here). Note
1239 that this does not affect the effective structure size, which should always be
1240 calculated with the header_sizeof() helper.
1241
1242 #define HEADER_END char end_field
1243 #define header_sizeof(type) offsetof(typeof(type), end_field)
1244
1245
1246 B. Stream Header Rationale
1247
1248 An event stream is divided in contiguous event packets of variable size. These
1249 subdivisions allow the trace analyzer to perform a fast binary search by time
1250 within the stream (typically requiring to index only the event packet headers)
1251 without reading the whole stream. These subdivisions have a variable size to
1252 eliminate the need to transfer the event packet padding when partially filled
1253 event packets must be sent when streaming a trace for live viewing/analysis.
1254 An event packet can contain a certain amount of padding at the end. Dividing
1255 streams into event packets is also useful for network streaming over UDP and
1256 flight recorder mode tracing (a whole event packet can be swapped out of the
1257 buffer atomically for reading).
1258
1259 The stream header is repeated at the beginning of each event packet to allow
1260 flexibility in terms of:
1261
1262 - streaming support,
1263 - allowing arbitrary buffers to be discarded without making the trace
1264 unreadable,
1265 - allow UDP packet loss handling by either dealing with missing event packet
1266 or asking for re-transmission.
1267 - transparently support flight recorder mode,
1268 - transparently support crash dump.
1269
1270
1271 C. TSDL Grammar
1272
1273 /*
1274 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
1275 *
1276 * Inspired from the C99 grammar:
1277 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
1278 * and c++1x grammar (draft)
1279 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
1280 *
1281 * Specialized for CTF needs by including only constant and declarations from
1282 * C99 (excluding function declarations), and by adding support for variants,
1283 * sequences and CTF-specific specifiers. Enumeration container types
1284 * semantic is inspired from c++1x enum-base.
1285 */
1286
1287 1) Lexical grammar
1288
1289 1.1) Lexical elements
1290
1291 token:
1292 keyword
1293 identifier
1294 constant
1295 string-literal
1296 punctuator
1297
1298 1.2) Keywords
1299
1300 keyword: is one of
1301
1302 align
1303 const
1304 char
1305 double
1306 enum
1307 event
1308 floating_point
1309 float
1310 integer
1311 int
1312 long
1313 short
1314 signed
1315 stream
1316 string
1317 struct
1318 trace
1319 typealias
1320 typedef
1321 unsigned
1322 variant
1323 void
1324 _Bool
1325 _Complex
1326 _Imaginary
1327
1328
1329 1.3) Identifiers
1330
1331 identifier:
1332 identifier-nondigit
1333 identifier identifier-nondigit
1334 identifier digit
1335
1336 identifier-nondigit:
1337 nondigit
1338 universal-character-name
1339 any other implementation-defined characters
1340
1341 nondigit:
1342 _
1343 [a-zA-Z] /* regular expression */
1344
1345 digit:
1346 [0-9] /* regular expression */
1347
1348 1.4) Universal character names
1349
1350 universal-character-name:
1351 \u hex-quad
1352 \U hex-quad hex-quad
1353
1354 hex-quad:
1355 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1356
1357 1.5) Constants
1358
1359 constant:
1360 integer-constant
1361 enumeration-constant
1362 character-constant
1363
1364 integer-constant:
1365 decimal-constant integer-suffix-opt
1366 octal-constant integer-suffix-opt
1367 hexadecimal-constant integer-suffix-opt
1368
1369 decimal-constant:
1370 nonzero-digit
1371 decimal-constant digit
1372
1373 octal-constant:
1374 0
1375 octal-constant octal-digit
1376
1377 hexadecimal-constant:
1378 hexadecimal-prefix hexadecimal-digit
1379 hexadecimal-constant hexadecimal-digit
1380
1381 hexadecimal-prefix:
1382 0x
1383 0X
1384
1385 nonzero-digit:
1386 [1-9]
1387
1388 integer-suffix:
1389 unsigned-suffix long-suffix-opt
1390 unsigned-suffix long-long-suffix
1391 long-suffix unsigned-suffix-opt
1392 long-long-suffix unsigned-suffix-opt
1393
1394 unsigned-suffix:
1395 u
1396 U
1397
1398 long-suffix:
1399 l
1400 L
1401
1402 long-long-suffix:
1403 ll
1404 LL
1405
1406 enumeration-constant:
1407 identifier
1408 string-literal
1409
1410 character-constant:
1411 ' c-char-sequence '
1412 L' c-char-sequence '
1413
1414 c-char-sequence:
1415 c-char
1416 c-char-sequence c-char
1417
1418 c-char:
1419 any member of source charset except single-quote ('), backslash
1420 (\), or new-line character.
1421 escape-sequence
1422
1423 escape-sequence:
1424 simple-escape-sequence
1425 octal-escape-sequence
1426 hexadecimal-escape-sequence
1427 universal-character-name
1428
1429 simple-escape-sequence: one of
1430 \' \" \? \\ \a \b \f \n \r \t \v
1431
1432 octal-escape-sequence:
1433 \ octal-digit
1434 \ octal-digit octal-digit
1435 \ octal-digit octal-digit octal-digit
1436
1437 hexadecimal-escape-sequence:
1438 \x hexadecimal-digit
1439 hexadecimal-escape-sequence hexadecimal-digit
1440
1441 1.6) String literals
1442
1443 string-literal:
1444 " s-char-sequence-opt "
1445 L" s-char-sequence-opt "
1446
1447 s-char-sequence:
1448 s-char
1449 s-char-sequence s-char
1450
1451 s-char:
1452 any member of source charset except double-quote ("), backslash
1453 (\), or new-line character.
1454 escape-sequence
1455
1456 1.7) Punctuators
1457
1458 punctuator: one of
1459 [ ] ( ) { } . -> * + - < > : ; ... = ,
1460
1461
1462 2) Phrase structure grammar
1463
1464 primary-expression:
1465 identifier
1466 constant
1467 string-literal
1468 ( unary-expression )
1469
1470 postfix-expression:
1471 primary-expression
1472 postfix-expression [ unary-expression ]
1473 postfix-expression . identifier
1474 postfix-expressoin -> identifier
1475
1476 unary-expression:
1477 postfix-expression
1478 unary-operator postfix-expression
1479
1480 unary-operator: one of
1481 + -
1482
1483 assignment-operator:
1484 =
1485
1486 type-assignment-operator:
1487 :=
1488
1489 constant-expression-range:
1490 unary-expression ... unary-expression
1491
1492 2.2) Declarations:
1493
1494 declaration:
1495 declaration-specifiers declarator-list-opt ;
1496 ctf-specifier ;
1497
1498 declaration-specifiers:
1499 storage-class-specifier declaration-specifiers-opt
1500 type-specifier declaration-specifiers-opt
1501 type-qualifier declaration-specifiers-opt
1502
1503 declarator-list:
1504 declarator
1505 declarator-list , declarator
1506
1507 abstract-declarator-list:
1508 abstract-declarator
1509 abstract-declarator-list , abstract-declarator
1510
1511 storage-class-specifier:
1512 typedef
1513
1514 type-specifier:
1515 void
1516 char
1517 short
1518 int
1519 long
1520 float
1521 double
1522 signed
1523 unsigned
1524 _Bool
1525 _Complex
1526 _Imaginary
1527 struct-specifier
1528 variant-specifier
1529 enum-specifier
1530 typedef-name
1531 ctf-type-specifier
1532
1533 align-attribute:
1534 align ( unary-expression )
1535
1536 struct-specifier:
1537 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1538 struct identifier align-attribute-opt
1539
1540 struct-or-variant-declaration-list:
1541 struct-or-variant-declaration
1542 struct-or-variant-declaration-list struct-or-variant-declaration
1543
1544 struct-or-variant-declaration:
1545 specifier-qualifier-list struct-or-variant-declarator-list ;
1546 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
1547 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1548 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
1549
1550 specifier-qualifier-list:
1551 type-specifier specifier-qualifier-list-opt
1552 type-qualifier specifier-qualifier-list-opt
1553
1554 struct-or-variant-declarator-list:
1555 struct-or-variant-declarator
1556 struct-or-variant-declarator-list , struct-or-variant-declarator
1557
1558 struct-or-variant-declarator:
1559 declarator
1560 declarator-opt : unary-expression
1561
1562 variant-specifier:
1563 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1564 variant identifier variant-tag
1565
1566 variant-tag:
1567 < unary-expression >
1568
1569 enum-specifier:
1570 enum identifier-opt { enumerator-list }
1571 enum identifier-opt { enumerator-list , }
1572 enum identifier
1573 enum identifier-opt : declaration-specifiers { enumerator-list }
1574 enum identifier-opt : declaration-specifiers { enumerator-list , }
1575
1576 enumerator-list:
1577 enumerator
1578 enumerator-list , enumerator
1579
1580 enumerator:
1581 enumeration-constant
1582 enumeration-constant assignment-operator unary-expression
1583 enumeration-constant assignment-operator constant-expression-range
1584
1585 type-qualifier:
1586 const
1587
1588 declarator:
1589 pointer-opt direct-declarator
1590
1591 direct-declarator:
1592 identifier
1593 ( declarator )
1594 direct-declarator [ unary-expression ]
1595
1596 abstract-declarator:
1597 pointer-opt direct-abstract-declarator
1598
1599 direct-abstract-declarator:
1600 identifier-opt
1601 ( abstract-declarator )
1602 direct-abstract-declarator [ unary-expression ]
1603 direct-abstract-declarator [ ]
1604
1605 pointer:
1606 * type-qualifier-list-opt
1607 * type-qualifier-list-opt pointer
1608
1609 type-qualifier-list:
1610 type-qualifier
1611 type-qualifier-list type-qualifier
1612
1613 typedef-name:
1614 identifier
1615
1616 2.3) CTF-specific declarations
1617
1618 ctf-specifier:
1619 event { ctf-assignment-expression-list-opt }
1620 stream { ctf-assignment-expression-list-opt }
1621 trace { ctf-assignment-expression-list-opt }
1622 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1623 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
1624
1625 ctf-type-specifier:
1626 floating_point { ctf-assignment-expression-list-opt }
1627 integer { ctf-assignment-expression-list-opt }
1628 string { ctf-assignment-expression-list-opt }
1629 string
1630
1631 ctf-assignment-expression-list:
1632 ctf-assignment-expression ;
1633 ctf-assignment-expression-list ctf-assignment-expression ;
1634
1635 ctf-assignment-expression:
1636 unary-expression assignment-operator unary-expression
1637 unary-expression type-assignment-operator type-specifier
1638 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
1639 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1640 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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