CTF: Get rid of duplicate OR
[ctf.git] / common-trace-format-specification.txt
1 Common Trace Format (CTF) Specification (v1.8.2)
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 Stream Event Context and 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 8. Clocks
69
70
71 1. Preliminary definitions
72
73 - Event Trace: An ordered sequence of events.
74 - Event Stream: An ordered sequence of events, containing a subset of the
75 trace event types.
76 - Event Packet: A sequence of physically contiguous events within an event
77 stream.
78 - Event: This is the basic entry in a trace. (aka: a trace record).
79 - An event identifier (ID) relates to the class (a type) of event within
80 an event stream.
81 e.g. event: irq_entry.
82 - An event (or event record) relates to a specific instance of an event
83 class.
84 e.g. event: irq_entry, at time X, on CPU Y
85 - Source Architecture: Architecture writing the trace.
86 - Reader Architecture: Architecture reading the trace.
87
88
89 2. High-level representation of a trace
90
91 A trace is divided into multiple event streams. Each event stream contains a
92 subset of the trace event types.
93
94 The final output of the trace, after its generation and optional transport over
95 the network, is expected to be either on permanent or temporary storage in a
96 virtual file system. Because each event stream is appended to while a trace is
97 being recorded, each is associated with a distinct set of files for
98 output. Therefore, a stored trace can be represented as a directory
99 containing zero, one or more files per stream.
100
101 Meta-data description associated with the trace contains information on
102 trace event types expressed in the Trace Stream Description Language
103 (TSDL). This language describes:
104
105 - Trace version.
106 - Types available.
107 - Per-trace event header description.
108 - Per-stream event header description.
109 - Per-stream event context description.
110 - Per-event
111 - Event type to stream mapping.
112 - Event type to name mapping.
113 - Event type to ID mapping.
114 - Event context description.
115 - Event fields description.
116
117
118 3. Event stream
119
120 An event stream can be divided into contiguous event packets of variable
121 size. An event packet can contain a certain amount of padding at the
122 end. The stream header is repeated at the beginning of each event
123 packet. The rationale for the event stream design choices is explained
124 in Appendix B. Stream Header 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 The base offset used for field alignment is the start of the packet
169 containing the field. For instance, a field aligned on 32-bit needs to
170 be at an offset multiple of 32-bit from the start of the packet that
171 contains it.
172
173 TSDL meta-data attribute representation of a specific alignment:
174
175 align = value; /* value in bits */
176
177 4.1.3 Byte order
178
179 By default, byte order of a basic type is the byte order described in
180 the trace description. It can be overridden by specifying a
181 "byte_order" attribute for a basic type. Typical use-case is to specify
182 the network byte order (big endian: "be") to save data captured from the
183 network into the trace without conversion.
184
185 TSDL meta-data representation:
186
187 byte_order = native OR network OR be OR le; /* network and be are aliases */
188
189 The "native" keyword selects the byte order described in the trace
190 description. The "network" byte order is an alias for big endian.
191
192 Even though the trace description section is not per se a type, for sake
193 of clarity, it should be noted that "native" and "network" byte orders
194 are only allowed within type declaration. The byte_order specified in
195 the trace description section only accepts "be" or "le" values.
196
197 4.1.4 Size
198
199 Type size, in bits, for integers and floats is that returned by "sizeof()" in C
200 multiplied by CHAR_BIT.
201 We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
202 to 8 bits for cross-endianness compatibility.
203
204 TSDL meta-data representation:
205
206 size = value; (value is in bits)
207
208 4.1.5 Integers
209
210 Signed integers are represented in two-complement. Integer alignment,
211 size, signedness and byte ordering are defined in the TSDL meta-data.
212 Integers aligned on byte size (8-bit) and with length multiple of byte
213 size (8-bit) correspond to the C99 standard integers. In addition,
214 integers with alignment and/or size that are _not_ a multiple of the
215 byte size are permitted; these correspond to the C99 standard bitfields,
216 with the added specification that the CTF integer bitfields have a fixed
217 binary representation. A MIT-licensed reference implementation of the
218 CTF portable bitfields is available at:
219
220 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
221
222 Binary representation of integers:
223
224 - On little and big endian:
225 - Within a byte, high bits correspond to an integer high bits, and low bits
226 correspond to low bits.
227 - On little endian:
228 - Integer across multiple bytes are placed from the less significant to the
229 most significant.
230 - Consecutive integers are placed from lower bits to higher bits (even within
231 a byte).
232 - On big endian:
233 - Integer across multiple bytes are placed from the most significant to the
234 less significant.
235 - Consecutive integers are placed from higher bits to lower bits (even within
236 a byte).
237
238 This binary representation is derived from the bitfield implementation in GCC
239 for little and big endian. However, contrary to what GCC does, integers can
240 cross units boundaries (no padding is required). Padding can be explicitly
241 added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
242
243 TSDL meta-data representation:
244
245 integer {
246 signed = true OR false; /* default false */
247 byte_order = native OR network OR be OR le; /* default native */
248 size = value; /* value in bits, no default */
249 align = value; /* value in bits */
250 /* based used for pretty-printing output, default: decimal. */
251 base = decimal OR dec OR d OR i OR u OR 10 OR hexadecimal OR hex OR x OR X OR p OR 16
252 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
253 /* character encoding, default: none */
254 encoding = none or UTF8 or ASCII;
255 }
256
257 Example of type inheritance (creation of a uint32_t named type):
258
259 typealias integer {
260 size = 32;
261 signed = false;
262 align = 32;
263 } := uint32_t;
264
265 Definition of a named 5-bit signed bitfield:
266
267 typealias integer {
268 size = 5;
269 signed = true;
270 align = 1;
271 } := int5_t;
272
273 The character encoding field can be used to specify that the integer
274 must be printed as a text character when read. e.g.:
275
276 typealias integer {
277 size = 8;
278 align = 8;
279 signed = false;
280 encoding = UTF8;
281 } := utf_char;
282
283
284 4.1.6 GNU/C bitfields
285
286 The GNU/C bitfields follow closely the integer representation, with a
287 particularity on alignment: if a bitfield cannot fit in the current unit, the
288 unit is padded and the bitfield starts at the following unit. The unit size is
289 defined by the size of the type "unit_type".
290
291 TSDL meta-data representation:
292
293 unit_type name:size;
294
295 As an example, the following structure declared in C compiled by GCC:
296
297 struct example {
298 short a:12;
299 short b:5;
300 };
301
302 The example structure is aligned on the largest element (short). The second
303 bitfield would be aligned on the next unit boundary, because it would not fit in
304 the current unit.
305
306 4.1.7 Floating point
307
308 The floating point values byte ordering is defined in the TSDL meta-data.
309
310 Floating point values follow the IEEE 754-2008 standard interchange formats.
311 Description of the floating point values include the exponent and mantissa size
312 in bits. Some requirements are imposed on the floating point values:
313
314 - FLT_RADIX must be 2.
315 - mant_dig is the number of digits represented in the mantissa. It is specified
316 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
317 LDBL_MANT_DIG as defined by <float.h>.
318 - exp_dig is the number of digits represented in the exponent. Given that
319 mant_dig is one bit more than its actual size in bits (leading 1 is not
320 needed) and also given that the sign bit always takes one bit, exp_dig can be
321 specified as:
322
323 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
324 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
325 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
326
327 TSDL meta-data representation:
328
329 floating_point {
330 exp_dig = value;
331 mant_dig = value;
332 byte_order = native OR network OR be OR le;
333 align = value;
334 }
335
336 Example of type inheritance:
337
338 typealias floating_point {
339 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
340 mant_dig = 24; /* FLT_MANT_DIG */
341 byte_order = native;
342 align = 32;
343 } := float;
344
345 TODO: define NaN, +inf, -inf behavior.
346
347 Bit-packed, byte-packed or larger alignments can be used for floating
348 point values, similarly to integers.
349
350 4.1.8 Enumerations
351
352 Enumerations are a mapping between an integer type and a table of strings. The
353 numerical representation of the enumeration follows the integer type specified
354 by the meta-data. The enumeration mapping table is detailed in the enumeration
355 description within the meta-data. The mapping table maps inclusive value
356 ranges (or single values) to strings. Instead of being limited to simple
357 "value -> string" mappings, these enumerations map
358 "[ start_value ... end_value ] -> string", which map inclusive ranges of
359 values to strings. An enumeration from the C language can be represented in
360 this format by having the same start_value and end_value for each element, which
361 is in fact a range of size 1. This single-value range is supported without
362 repeating the start and end values with the value = string declaration.
363
364 enum name : integer_type {
365 somestring = start_value1 ... end_value1,
366 "other string" = start_value2 ... end_value2,
367 yet_another_string, /* will be assigned to end_value2 + 1 */
368 "some other string" = value,
369 ...
370 };
371
372 If the values are omitted, the enumeration starts at 0 and increment of 1 for
373 each entry. An entry with omitted value that follows a range entry takes
374 as value the end_value of the previous range + 1:
375
376 enum name : unsigned int {
377 ZERO,
378 ONE,
379 TWO,
380 TEN = 10,
381 ELEVEN,
382 };
383
384 Overlapping ranges within a single enumeration are implementation defined.
385
386 A nameless enumeration can be declared as a field type or as part of a typedef:
387
388 enum : integer_type {
389 ...
390 }
391
392 Enumerations omitting the container type ": integer_type" use the "int"
393 type (for compatibility with C99). The "int" type must be previously
394 declared. E.g.:
395
396 typealias integer { size = 32; align = 32; signed = true; } := int;
397
398 enum {
399 ...
400 }
401
402
403 4.2 Compound types
404
405 Compound are aggregation of type declarations. Compound types include
406 structures, variant, arrays, sequences, and strings.
407
408 4.2.1 Structures
409
410 Structures are aligned on the largest alignment required by basic types
411 contained within the structure. (This follows the ISO/C standard for structures)
412
413 TSDL meta-data representation of a named structure:
414
415 struct name {
416 field_type field_name;
417 field_type field_name;
418 ...
419 };
420
421 Example:
422
423 struct example {
424 integer { /* Nameless type */
425 size = 16;
426 signed = true;
427 align = 16;
428 } first_field_name;
429 uint64_t second_field_name; /* Named type declared in the meta-data */
430 };
431
432 The fields are placed in a sequence next to each other. They each
433 possess a field name, which is a unique identifier within the structure.
434 The identifier is not allowed to use any reserved keyword
435 (see Section C.1.2). Replacing reserved keywords with
436 underscore-prefixed field names is recommended. Fields starting with an
437 underscore should have their leading underscore removed by the CTF trace
438 readers.
439
440 A nameless structure can be declared as a field type or as part of a typedef:
441
442 struct {
443 ...
444 }
445
446 Alignment for a structure compound type can be forced to a minimum value
447 by adding an "align" specifier after the declaration of a structure
448 body. This attribute is read as: align(value). The value is specified in
449 bits. The structure will be aligned on the maximum value between this
450 attribute and the alignment required by the basic types contained within
451 the structure. e.g.
452
453 struct {
454 ...
455 } align(32)
456
457 4.2.2 Variants (Discriminated/Tagged Unions)
458
459 A CTF variant is a selection between different types. A CTF variant must
460 always be defined within the scope of a structure or within fields
461 contained within a structure (defined recursively). A "tag" enumeration
462 field must appear in either the same static scope, prior to the variant
463 field (in field declaration order), in an upper static scope , or in an
464 upper dynamic scope (see Section 7.3.2). The type selection is indicated
465 by the mapping from the enumeration value to the string used as variant
466 type selector. The field to use as tag is specified by the "tag_field",
467 specified between "< >" after the "variant" keyword for unnamed
468 variants, and after "variant name" for named variants.
469
470 The alignment of the variant is the alignment of the type as selected by
471 the tag value for the specific instance of the variant. The size of the
472 variant is the size as selected by the tag value for the specific
473 instance of the variant.
474
475 The alignment of the type containing the variant is independent of the
476 variant alignment. For instance, if a structure contains two fields, a
477 32-bit integer, aligned on 32 bits, and a variant, which contains two
478 choices: either a 32-bit field, aligned on 32 bits, or a 64-bit field,
479 aligned on 64 bits, the alignment of the outmost structure will be
480 32-bit (the alignment of its largest field, disregarding the alignment
481 of the variant). The alignment of the variant will depend on the
482 selector: if the variant's 32-bit field is selected, its alignment will
483 be 32-bit, or 64-bit otherwise. It is important to note that variants
484 are specifically tailored for compactness in a stream. Therefore, the
485 relative offsets of compound type fields can vary depending on
486 the offset at which the compound type starts if it contains a variant
487 that itself contains a type with alignment larger than the largest field
488 contained within the compound type. This is caused by the fact that the
489 compound type may contain the enumeration that select the variant's
490 choice, and therefore the alignment to be applied to the compound type
491 cannot be determined before encountering the enumeration.
492
493 Each variant type selector possess a field name, which is a unique
494 identifier within the variant. The identifier is not allowed to use any
495 reserved keyword (see Section C.1.2). Replacing reserved keywords with
496 underscore-prefixed field names is recommended. Fields starting with an
497 underscore should have their leading underscore removed by the CTF trace
498 readers.
499
500
501 A named variant declaration followed by its definition within a structure
502 declaration:
503
504 variant name {
505 field_type sel1;
506 field_type sel2;
507 field_type sel3;
508 ...
509 };
510
511 struct {
512 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
513 ...
514 variant name <tag_field> v;
515 }
516
517 An unnamed variant definition within a structure is expressed by the following
518 TSDL meta-data:
519
520 struct {
521 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
522 ...
523 variant <tag_field> {
524 field_type sel1;
525 field_type sel2;
526 field_type sel3;
527 ...
528 } v;
529 }
530
531 Example of a named variant within a sequence that refers to a single tag field:
532
533 variant example {
534 uint32_t a;
535 uint64_t b;
536 short c;
537 };
538
539 struct {
540 enum : uint2_t { a, b, c } choice;
541 unsigned int seqlen;
542 variant example <choice> v[seqlen];
543 }
544
545 Example of an unnamed variant:
546
547 struct {
548 enum : uint2_t { a, b, c, d } choice;
549 /* Unrelated fields can be added between the variant and its tag */
550 int32_t somevalue;
551 variant <choice> {
552 uint32_t a;
553 uint64_t b;
554 short c;
555 struct {
556 unsigned int field1;
557 uint64_t field2;
558 } d;
559 } s;
560 }
561
562 Example of an unnamed variant within an array:
563
564 struct {
565 enum : uint2_t { a, b, c } choice;
566 variant <choice> {
567 uint32_t a;
568 uint64_t b;
569 short c;
570 } v[10];
571 }
572
573 Example of a variant type definition within a structure, where the defined type
574 is then declared within an array of structures. This variant refers to a tag
575 located in an upper static scope. This example clearly shows that a variant
576 type definition referring to the tag "x" uses the closest preceding field from
577 the static scope of the type definition.
578
579 struct {
580 enum : uint2_t { a, b, c, d } x;
581
582 typedef variant <x> { /*
583 * "x" refers to the preceding "x" enumeration in the
584 * static scope of the type definition.
585 */
586 uint32_t a;
587 uint64_t b;
588 short c;
589 } example_variant;
590
591 struct {
592 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
593 example_variant v; /*
594 * "v" uses the "enum : uint2_t { a, b, c, d }"
595 * tag.
596 */
597 } a[10];
598 }
599
600 4.2.3 Arrays
601
602 Arrays are fixed-length. Their length is declared in the type
603 declaration within the meta-data. They contain an array of "inner type"
604 elements, which can refer to any type not containing the type of the
605 array being declared (no circular dependency). The length is the number
606 of elements in an array.
607
608 TSDL meta-data representation of a named array:
609
610 typedef elem_type name[length];
611
612 A nameless array can be declared as a field type within a structure, e.g.:
613
614 uint8_t field_name[10];
615
616 Arrays are always aligned on their element alignment requirement.
617
618 4.2.4 Sequences
619
620 Sequences are dynamically-sized arrays. They refer to a "length"
621 unsigned integer field, which must appear in either the same static scope,
622 prior to the sequence field (in field declaration order), in an upper
623 static scope, or in an upper dynamic scope (see Section 7.3.2). This
624 length field represents the number of elements in the sequence. The
625 sequence per se is an array of "inner type" elements.
626
627 TSDL meta-data representation for a sequence type definition:
628
629 struct {
630 unsigned int length_field;
631 typedef elem_type typename[length_field];
632 typename seq_field_name;
633 }
634
635 A sequence can also be declared as a field type, e.g.:
636
637 struct {
638 unsigned int length_field;
639 long seq_field_name[length_field];
640 }
641
642 Multiple sequences can refer to the same length field, and these length
643 fields can be in a different upper dynamic scope:
644
645 e.g., assuming the stream.event.header defines:
646
647 stream {
648 ...
649 id = 1;
650 event.header := struct {
651 uint16_t seq_len;
652 };
653 };
654
655 event {
656 ...
657 stream_id = 1;
658 fields := struct {
659 long seq_a[stream.event.header.seq_len];
660 char seq_b[stream.event.header.seq_len];
661 };
662 };
663
664 The sequence elements follow the "array" specifications.
665
666 4.2.5 Strings
667
668 Strings are an array of bytes of variable size and are terminated by a '\0'
669 "NULL" character. Their encoding is described in the TSDL meta-data. In
670 absence of encoding attribute information, the default encoding is
671 UTF-8.
672
673 TSDL meta-data representation of a named string type:
674
675 typealias string {
676 encoding = UTF8 OR ASCII;
677 } := name;
678
679 A nameless string type can be declared as a field type:
680
681 string field_name; /* Use default UTF8 encoding */
682
683 Strings are always aligned on byte size.
684
685 5. Event Packet Header
686
687 The event packet header consists of two parts: the "event packet header"
688 is the same for all streams of a trace. The second part, the "event
689 packet context", is described on a per-stream basis. Both are described
690 in the TSDL meta-data.
691
692 Event packet header (all fields are optional, specified by TSDL meta-data):
693
694 - Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
695 CTF packet. This magic number is optional, but when present, it should
696 come at the very beginning of the packet.
697 - Trace UUID, used to ensure the event packet match the meta-data used.
698 (note: we cannot use a meta-data checksum in every cases instead of a
699 UUID because meta-data can be appended to while tracing is active)
700 This field is optional.
701 - Stream ID, used as reference to stream description in meta-data.
702 This field is optional if there is only one stream description in the
703 meta-data, but becomes required if there are more than one stream in
704 the TSDL meta-data description.
705
706 Event packet context (all fields are optional, specified by TSDL meta-data):
707
708 - Event packet content size (in bits).
709 - Event packet size (in bits, includes padding).
710 - Event packet content checksum. Checksum excludes the event packet
711 header.
712 - Per-stream event packet sequence count (to deal with UDP packet loss). The
713 number of significant sequence counter bits should also be present, so
714 wrap-arounds are dealt with correctly.
715 - Time-stamp at the beginning and time-stamp at the end of the event packet.
716 Both timestamps are written in the packet header, but sampled respectively
717 while (or before) writing the first event and while (or after) writing the
718 last event in the packet. The inclusive range between these timestamps should
719 include all event timestamps assigned to events contained within the packet.
720 See Section 8. Clocks for more detail.
721 - Events discarded count
722 - Snapshot of a per-stream free-running counter, counting the number of
723 events discarded that were supposed to be written in the stream after
724 the last event in the event packet.
725 * Note: producer-consumer buffer full condition can fill the current
726 event packet with padding so we know exactly where events have been
727 discarded. However, if the buffer full condition chooses not
728 to fill the current event packet with padding, all we know
729 about the timestamp range in which the events have been
730 discarded is that it is somewhere between the beginning and
731 the end of the packet.
732 - Lossless compression scheme used for the event packet content. Applied
733 directly to raw data. New types of compression can be added in following
734 versions of the format.
735 0: no compression scheme
736 1: bzip2
737 2: gzip
738 3: xz
739 - Cypher used for the event packet content. Applied after compression.
740 0: no encryption
741 1: AES
742 - Checksum scheme used for the event packet content. Applied after encryption.
743 0: no checksum
744 1: md5
745 2: sha1
746 3: crc32
747
748 5.1 Event Packet Header Description
749
750 The event packet header layout is indicated by the trace packet.header
751 field. Here is a recommended structure type for the packet header with
752 the fields typically expected (although these fields are each optional):
753
754 struct event_packet_header {
755 uint32_t magic;
756 uint8_t uuid[16];
757 uint32_t stream_id;
758 };
759
760 trace {
761 ...
762 packet.header := struct event_packet_header;
763 };
764
765 If the magic number is not present, tools such as "file" will have no
766 mean to discover the file type.
767
768 If the uuid is not present, no validation that the meta-data actually
769 corresponds to the stream is performed.
770
771 If the stream_id packet header field is missing, the trace can only
772 contain a single stream. Its "id" field can be left out, and its events
773 don't need to declare a "stream_id" field.
774
775
776 5.2 Event Packet Context Description
777
778 Event packet context example. These are declared within the stream declaration
779 in the meta-data. All these fields are optional. If the packet size field is
780 missing, the whole stream only contains a single packet. If the content
781 size field is missing, the packet is filled (no padding). The content
782 and packet sizes include all headers.
783
784 An example event packet context type:
785
786 struct event_packet_context {
787 uint64_t timestamp_begin;
788 uint64_t timestamp_end;
789 uint32_t checksum;
790 uint32_t stream_packet_count;
791 uint32_t events_discarded;
792 uint32_t cpu_id;
793 uint64_t/uint32_t/uint16_t content_size;
794 uint64_t/uint32_t/uint16_t packet_size;
795 uint8_t compression_scheme;
796 uint8_t encryption_scheme;
797 uint8_t checksum_scheme;
798 };
799
800
801 6. Event Structure
802
803 The overall structure of an event is:
804
805 1 - Event Header (as specified by the stream meta-data)
806 2 - Stream Event Context (as specified by the stream meta-data)
807 3 - Event Context (as specified by the event meta-data)
808 4 - Event Payload (as specified by the event meta-data)
809
810 This structure defines an implicit dynamic scoping, where variants
811 located in inner structures (those with a higher number in the listing
812 above) can refer to the fields of outer structures (with lower number in
813 the listing above). See Section 7.3 TSDL Scopes for more detail.
814
815 6.1 Event Header
816
817 Event headers can be described within the meta-data. We hereby propose, as an
818 example, two types of events headers. Type 1 accommodates streams with less than
819 31 event IDs. Type 2 accommodates streams with 31 or more event IDs.
820
821 One major factor can vary between streams: the number of event IDs assigned to
822 a stream. Luckily, this information tends to stay relatively constant (modulo
823 event registration while trace is being recorded), so we can specify different
824 representations for streams containing few event IDs and streams containing
825 many event IDs, so we end up representing the event ID and time-stamp as
826 densely as possible in each case.
827
828 The header is extended in the rare occasions where the information cannot be
829 represented in the ranges available in the standard event header. They are also
830 used in the rare occasions where the data required for a field could not be
831 collected: the flag corresponding to the missing field within the missing_fields
832 array is then set to 1.
833
834 Types uintX_t represent an X-bit unsigned integer, as declared with
835 either:
836
837 typealias integer { size = X; align = X; signed = false; } := uintX_t;
838
839 or
840
841 typealias integer { size = X; align = 1; signed = false; } := uintX_t;
842
843 For more information about timestamp fields, see Section 8. Clocks.
844
845 6.1.1 Type 1 - Few event IDs
846
847 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
848 preference).
849 - Native architecture byte ordering.
850 - For "compact" selection
851 - Fixed size: 32 bits.
852 - For "extended" selection
853 - Size depends on the architecture and variant alignment.
854
855 struct event_header_1 {
856 /*
857 * id: range: 0 - 30.
858 * id 31 is reserved to indicate an extended header.
859 */
860 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
861 variant <id> {
862 struct {
863 uint27_t timestamp;
864 } compact;
865 struct {
866 uint32_t id; /* 32-bit event IDs */
867 uint64_t timestamp; /* 64-bit timestamps */
868 } extended;
869 } v;
870 } align(32); /* or align(8) */
871
872
873 6.1.2 Type 2 - Many event IDs
874
875 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
876 preference).
877 - Native architecture byte ordering.
878 - For "compact" selection
879 - Size depends on the architecture and variant alignment.
880 - For "extended" selection
881 - Size depends on the architecture and variant alignment.
882
883 struct event_header_2 {
884 /*
885 * id: range: 0 - 65534.
886 * id 65535 is reserved to indicate an extended header.
887 */
888 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
889 variant <id> {
890 struct {
891 uint32_t timestamp;
892 } compact;
893 struct {
894 uint32_t id; /* 32-bit event IDs */
895 uint64_t timestamp; /* 64-bit timestamps */
896 } extended;
897 } v;
898 } align(16); /* or align(8) */
899
900
901 6.2 Stream Event Context and Event Context
902
903 The event context contains information relative to the current event.
904 The choice and meaning of this information is specified by the TSDL
905 stream and event meta-data descriptions. The stream context is applied
906 to all events within the stream. The stream context structure follows
907 the event header. The event context is applied to specific events. Its
908 structure follows the stream context structure.
909
910 An example of stream-level event context is to save the event payload size with
911 each event, or to save the current PID with each event. These are declared
912 within the stream declaration within the meta-data:
913
914 stream {
915 ...
916 event.context := struct {
917 uint pid;
918 uint16_t payload_size;
919 };
920 };
921
922 An example of event-specific event context is to declare a bitmap of missing
923 fields, only appended after the stream event context if the extended event
924 header is selected. NR_FIELDS is the number of fields within the event (a
925 numeric value).
926
927 event {
928 context = struct {
929 variant <id> {
930 struct { } compact;
931 struct {
932 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
933 } extended;
934 } v;
935 };
936 ...
937 }
938
939 6.3 Event Payload
940
941 An event payload contains fields specific to a given event type. The fields
942 belonging to an event type are described in the event-specific meta-data
943 within a structure type.
944
945 6.3.1 Padding
946
947 No padding at the end of the event payload. This differs from the ISO/C standard
948 for structures, but follows the CTF standard for structures. In a trace, even
949 though it makes sense to align the beginning of a structure, it really makes no
950 sense to add padding at the end of the structure, because structures are usually
951 not followed by a structure of the same type.
952
953 This trick can be done by adding a zero-length "end" field at the end of the C
954 structures, and by using the offset of this field rather than using sizeof()
955 when calculating the size of a structure (see Appendix "A. Helper macros").
956
957 6.3.2 Alignment
958
959 The event payload is aligned on the largest alignment required by types
960 contained within the payload. (This follows the ISO/C standard for structures)
961
962
963 7. Trace Stream Description Language (TSDL)
964
965 The Trace Stream Description Language (TSDL) allows expression of the
966 binary trace streams layout in a C99-like Domain Specific Language
967 (DSL).
968
969
970 7.1 Meta-data
971
972 The trace stream layout description is located in the trace meta-data.
973 The meta-data is itself located in a stream identified by its name:
974 "metadata".
975
976 The meta-data description can be expressed in two different formats:
977 text-only and packet-based. The text-only description facilitates
978 generation of meta-data and provides a convenient way to enter the
979 meta-data information by hand. The packet-based meta-data provides the
980 CTF stream packet facilities (checksumming, compression, encryption,
981 network-readiness) for meta-data stream generated and transported by a
982 tracer.
983
984 The text-only meta-data file is a plain-text TSDL description. This file
985 must begin with the following characters to identify the file as a CTF
986 TSDL text-based metadata file (without the double-quotes) :
987
988 "/* CTF"
989
990 It must be followed by a space, and the version of the specification
991 followed by the CTF trace, e.g.:
992
993 " 1.8"
994
995 These characters allow automated discovery of file type and CTF
996 specification version. They are interpreted as a the beginning of a
997 comment by the TSDL metadata parser. The comment can be continued to
998 contain extra commented characters before it is closed.
999
1000 The packet-based meta-data is made of "meta-data packets", which each
1001 start with a meta-data packet header. The packet-based meta-data
1002 description is detected by reading the magic number "0x75D11D57" at the
1003 beginning of the file. This magic number is also used to detect the
1004 endianness of the architecture by trying to read the CTF magic number
1005 and its counterpart in reversed endianness. The events within the
1006 meta-data stream have no event header nor event context. Each event only
1007 contains a special "sequence" payload, which is a sequence of bits which
1008 length is implicitly calculated by using the
1009 "trace.packet.header.content_size" field, minus the packet header size.
1010 The formatting of this sequence of bits is a plain-text representation
1011 of the TSDL description. Each meta-data packet start with a special
1012 packet header, specific to the meta-data stream, which contains,
1013 exactly:
1014
1015 struct metadata_packet_header {
1016 uint32_t magic; /* 0x75D11D57 */
1017 uint8_t uuid[16]; /* Unique Universal Identifier */
1018 uint32_t checksum; /* 0 if unused */
1019 uint32_t content_size; /* in bits */
1020 uint32_t packet_size; /* in bits */
1021 uint8_t compression_scheme; /* 0 if unused */
1022 uint8_t encryption_scheme; /* 0 if unused */
1023 uint8_t checksum_scheme; /* 0 if unused */
1024 uint8_t major; /* CTF spec version major number */
1025 uint8_t minor; /* CTF spec version minor number */
1026 };
1027
1028 The packet-based meta-data can be converted to a text-only meta-data by
1029 concatenating all the strings it contains.
1030
1031 In the textual representation of the meta-data, the text contained
1032 within "/*" and "*/", as well as within "//" and end of line, are
1033 treated as comments. Boolean values can be represented as true, TRUE,
1034 or 1 for true, and false, FALSE, or 0 for false. Within the string-based
1035 meta-data description, the trace UUID is represented as a string of
1036 hexadecimal digits and dashes "-". In the event packet header, the trace
1037 UUID is represented as an array of bytes.
1038
1039
1040 7.2 Declaration vs Definition
1041
1042 A declaration associates a layout to a type, without specifying where
1043 this type is located in the event structure hierarchy (see Section 6).
1044 This therefore includes typedef, typealias, as well as all type
1045 specifiers. In certain circumstances (typedef, structure field and
1046 variant field), a declaration is followed by a declarator, which specify
1047 the newly defined type name (for typedef), or the field name (for
1048 declarations located within structure and variants). Array and sequence,
1049 declared with square brackets ("[" "]"), are part of the declarator,
1050 similarly to C99. The enumeration base type is specified by
1051 ": enum_base", which is part of the type specifier. The variant tag
1052 name, specified between "<" ">", is also part of the type specifier.
1053
1054 A definition associates a type to a location in the event structure
1055 hierarchy (see Section 6). This association is denoted by ":=", as shown
1056 in Section 7.3.
1057
1058
1059 7.3 TSDL Scopes
1060
1061 TSDL uses three different types of scoping: a lexical scope is used for
1062 declarations and type definitions, and static and dynamic scopes are
1063 used for variants references to tag fields (with relative and absolute
1064 path lookups) and for sequence references to length fields.
1065
1066 7.3.1 Lexical Scope
1067
1068 Each of "trace", "env", "stream", "event", "struct" and "variant" have
1069 their own nestable declaration scope, within which types can be declared
1070 using "typedef" and "typealias". A root declaration scope also contains
1071 all declarations located outside of any of the aforementioned
1072 declarations. An inner declaration scope can refer to type declared
1073 within its container lexical scope prior to the inner declaration scope.
1074 Redefinition of a typedef or typealias is not valid, although hiding an
1075 upper scope typedef or typealias is allowed within a sub-scope.
1076
1077 7.3.2 Static and Dynamic Scopes
1078
1079 A local static scope consists in the scope generated by the declaration
1080 of fields within a compound type. A static scope is a local static scope
1081 augmented with the nested sub-static-scopes it contains.
1082
1083 A dynamic scope consists in the static scope augmented with the
1084 implicit event structure definition hierarchy presented at Section 6.
1085
1086 Multiple declarations of the same field name within a local static scope
1087 is not valid. It is however valid to re-use the same field name in
1088 different local scopes.
1089
1090 Nested static and dynamic scopes form lookup paths. These are used for
1091 variant tag and sequence length references. They are used at the variant
1092 and sequence definition site to look up the location of the tag field
1093 associated with a variant, and to lookup up the location of the length
1094 field associated with a sequence.
1095
1096 Variants and sequences can refer to a tag field either using a relative
1097 path or an absolute path. The relative path is relative to the scope in
1098 which the variant or sequence performing the lookup is located.
1099 Relative paths are only allowed to lookup within the same static scope,
1100 which includes its nested static scopes. Lookups targeting parent static
1101 scopes need to be performed with an absolute path.
1102
1103 Absolute path lookups use the full path including the dynamic scope
1104 followed by a "." and then the static scope. Therefore, variants (or
1105 sequences) in lower levels in the dynamic scope (e.g. event context) can
1106 refer to a tag (or length) field located in upper levels (e.g. in the
1107 event header) by specifying, in this case, the associated tag with
1108 <stream.event.header.field_name>. This allows, for instance, the event
1109 context to define a variant referring to the "id" field of the event
1110 header as selector.
1111
1112 The dynamic scope prefixes are thus:
1113
1114 - Trace Environment: <env. >,
1115 - Trace Packet Header: <trace.packet.header. >,
1116 - Stream Packet Context: <stream.packet.context. >,
1117 - Event Header: <stream.event.header. >,
1118 - Stream Event Context: <stream.event.context. >,
1119 - Event Context: <event.context. >,
1120 - Event Payload: <event.fields. >.
1121
1122
1123 The target dynamic scope must be specified explicitly when referring to
1124 a field outside of the static scope (absolute scope reference). No
1125 conflict can occur between relative and dynamic paths, because the
1126 keywords "trace", "stream", and "event" are reserved, and thus
1127 not permitted as field names. It is recommended that field names
1128 clashing with CTF and C99 reserved keywords use an underscore prefix to
1129 eliminate the risk of generating a description containing an invalid
1130 field name. Consequently, fields starting with an underscore should have
1131 their leading underscore removed by the CTF trace readers.
1132
1133
1134 The information available in the dynamic scopes can be thought of as the
1135 current tracing context. At trace production, information about the
1136 current context is saved into the specified scope field levels. At trace
1137 consumption, for each event, the current trace context is therefore
1138 readable by accessing the upper dynamic scopes.
1139
1140
1141 7.4 TSDL Examples
1142
1143 The grammar representing the TSDL meta-data is presented in Appendix C.
1144 TSDL Grammar. This section presents a rather lighter reading that
1145 consists in examples of TSDL meta-data, with template values.
1146
1147 The stream "id" can be left out if there is only one stream in the
1148 trace. The event "id" field can be left out if there is only one event
1149 in a stream.
1150
1151 trace {
1152 major = value; /* CTF spec version major number */
1153 minor = value; /* CTF spec version minor number */
1154 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
1155 byte_order = be OR le; /* Endianness (required) */
1156 packet.header := struct {
1157 uint32_t magic;
1158 uint8_t uuid[16];
1159 uint32_t stream_id;
1160 };
1161 };
1162
1163 /*
1164 * The "env" (environment) scope contains assignment expressions. The
1165 * field names and content are implementation-defined.
1166 */
1167 env {
1168 pid = value; /* example */
1169 proc_name = "name"; /* example */
1170 ...
1171 };
1172
1173 stream {
1174 id = stream_id;
1175 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
1176 event.header := event_header_1 OR event_header_2;
1177 event.context := struct {
1178 ...
1179 };
1180 packet.context := struct {
1181 ...
1182 };
1183 };
1184
1185 event {
1186 name = "event_name";
1187 id = value; /* Numeric identifier within the stream */
1188 stream_id = stream_id;
1189 loglevel = value;
1190 model.emf.uri = "string";
1191 context := struct {
1192 ...
1193 };
1194 fields := struct {
1195 ...
1196 };
1197 };
1198
1199 callsite {
1200 name = "event_name";
1201 func = "func_name";
1202 file = "myfile.c";
1203 line = 39;
1204 ip = 0x40096c;
1205 };
1206
1207 /* More detail on types in section 4. Types */
1208
1209 /*
1210 * Named types:
1211 *
1212 * Type declarations behave similarly to the C standard.
1213 */
1214
1215 typedef aliased_type_specifiers new_type_declarators;
1216
1217 /* e.g.: typedef struct example new_type_name[10]; */
1218
1219 /*
1220 * typealias
1221 *
1222 * The "typealias" declaration can be used to give a name (including
1223 * pointer declarator specifier) to a type. It should also be used to
1224 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1225 * Typealias is a superset of "typedef": it also allows assignment of a
1226 * simple variable identifier to a type.
1227 */
1228
1229 typealias type_class {
1230 ...
1231 } := type_specifiers type_declarator;
1232
1233 /*
1234 * e.g.:
1235 * typealias integer {
1236 * size = 32;
1237 * align = 32;
1238 * signed = false;
1239 * } := struct page *;
1240 *
1241 * typealias integer {
1242 * size = 32;
1243 * align = 32;
1244 * signed = true;
1245 * } := int;
1246 */
1247
1248 struct name {
1249 ...
1250 };
1251
1252 variant name {
1253 ...
1254 };
1255
1256 enum name : integer_type {
1257 ...
1258 };
1259
1260
1261 /*
1262 * Unnamed types, contained within compound type fields, typedef or typealias.
1263 */
1264
1265 struct {
1266 ...
1267 }
1268
1269 struct {
1270 ...
1271 } align(value)
1272
1273 variant {
1274 ...
1275 }
1276
1277 enum : integer_type {
1278 ...
1279 }
1280
1281 typedef type new_type[length];
1282
1283 struct {
1284 type field_name[length];
1285 }
1286
1287 typedef type new_type[length_type];
1288
1289 struct {
1290 type field_name[length_type];
1291 }
1292
1293 integer {
1294 ...
1295 }
1296
1297 floating_point {
1298 ...
1299 }
1300
1301 struct {
1302 integer_type field_name:size; /* GNU/C bitfield */
1303 }
1304
1305 struct {
1306 string field_name;
1307 }
1308
1309
1310 8. Clocks
1311
1312 Clock metadata allows to describe the clock topology of the system, as
1313 well as to detail each clock parameter. In absence of clock description,
1314 it is assumed that all fields named "timestamp" use the same clock
1315 source, which increments once per nanosecond.
1316
1317 Describing a clock and how it is used by streams is threefold: first,
1318 the clock and clock topology should be described in a "clock"
1319 description block, e.g.:
1320
1321 clock {
1322 name = cycle_counter_sync;
1323 uuid = "62189bee-96dc-11e0-91a8-cfa3d89f3923";
1324 description = "Cycle counter synchronized across CPUs";
1325 freq = 1000000000; /* frequency, in Hz */
1326 /* precision in seconds is: 1000 * (1/freq) */
1327 precision = 1000;
1328 /*
1329 * clock value offset from Epoch is:
1330 * offset_s + (offset * (1/freq))
1331 */
1332 offset_s = 1326476837;
1333 offset = 897235420;
1334 absolute = FALSE;
1335 };
1336
1337 The mandatory "name" field specifies the name of the clock identifier,
1338 which can later be used as a reference. The optional field "uuid" is the
1339 unique identifier of the clock. It can be used to correlate different
1340 traces that use the same clock. An optional textual description string
1341 can be added with the "description" field. The "freq" field is the
1342 initial frequency of the clock, in Hz. If the "freq" field is not
1343 present, the frequency is assumed to be 1000000000 (providing clock
1344 increment of 1 ns). The optional "precision" field details the
1345 uncertainty on the clock measurements, in (1/freq) units. The "offset_s"
1346 and "offset" fields indicate the offset from POSIX.1 Epoch, 1970-01-01
1347 00:00:00 +0000 (UTC), to the zero of value of the clock. The "offset_s"
1348 field is in seconds. The "offset" field is in (1/freq) units. If any of
1349 the "offset_s" or "offset" field is not present, it is assigned the 0
1350 value. The field "absolute" is TRUE if the clock is a global reference
1351 across different clock uuid (e.g. NTP time). Otherwise, "absolute" is
1352 FALSE, and the clock can be considered as synchronized only with other
1353 clocks that have the same uuid.
1354
1355
1356 Secondly, a reference to this clock should be added within an integer
1357 type:
1358
1359 typealias integer {
1360 size = 64; align = 1; signed = false;
1361 map = clock.cycle_counter_sync.value;
1362 } := uint64_ccnt_t;
1363
1364 Thirdly, stream declarations can reference the clock they use as a
1365 time-stamp source:
1366
1367 struct packet_context {
1368 uint64_ccnt_t ccnt_begin;
1369 uint64_ccnt_t ccnt_end;
1370 /* ... */
1371 };
1372
1373 stream {
1374 /* ... */
1375 event.header := struct {
1376 uint64_ccnt_t timestamp;
1377 /* ... */
1378 }
1379 packet.context := struct packet_context;
1380 };
1381
1382 For a N-bit integer type referring to a clock, if the integer overflows
1383 compared to the N low order bits of the clock prior value found in the
1384 same stream, then it is assumed that one, and only one, overflow
1385 occurred. It is therefore important that events encoding time on a small
1386 number of bits happen frequently enough to detect when more than one
1387 N-bit overflow occurs.
1388
1389 In a packet context, clock field names ending with "_begin" and "_end"
1390 have a special meaning: this refers to the time-stamps at, respectively,
1391 the beginning and the end of each packet.
1392
1393
1394 A. Helper macros
1395
1396 The two following macros keep track of the size of a GNU/C structure without
1397 padding at the end by placing HEADER_END as the last field. A one byte end field
1398 is used for C90 compatibility (C99 flexible arrays could be used here). Note
1399 that this does not affect the effective structure size, which should always be
1400 calculated with the header_sizeof() helper.
1401
1402 #define HEADER_END char end_field
1403 #define header_sizeof(type) offsetof(typeof(type), end_field)
1404
1405
1406 B. Stream Header Rationale
1407
1408 An event stream is divided in contiguous event packets of variable size. These
1409 subdivisions allow the trace analyzer to perform a fast binary search by time
1410 within the stream (typically requiring to index only the event packet headers)
1411 without reading the whole stream. These subdivisions have a variable size to
1412 eliminate the need to transfer the event packet padding when partially filled
1413 event packets must be sent when streaming a trace for live viewing/analysis.
1414 An event packet can contain a certain amount of padding at the end. Dividing
1415 streams into event packets is also useful for network streaming over UDP and
1416 flight recorder mode tracing (a whole event packet can be swapped out of the
1417 buffer atomically for reading).
1418
1419 The stream header is repeated at the beginning of each event packet to allow
1420 flexibility in terms of:
1421
1422 - streaming support,
1423 - allowing arbitrary buffers to be discarded without making the trace
1424 unreadable,
1425 - allow UDP packet loss handling by either dealing with missing event packet
1426 or asking for re-transmission.
1427 - transparently support flight recorder mode,
1428 - transparently support crash dump.
1429
1430
1431 C. TSDL Grammar
1432
1433 /*
1434 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
1435 *
1436 * Inspired from the C99 grammar:
1437 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
1438 * and c++1x grammar (draft)
1439 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
1440 *
1441 * Specialized for CTF needs by including only constant and declarations from
1442 * C99 (excluding function declarations), and by adding support for variants,
1443 * sequences and CTF-specific specifiers. Enumeration container types
1444 * semantic is inspired from c++1x enum-base.
1445 */
1446
1447 1) Lexical grammar
1448
1449 1.1) Lexical elements
1450
1451 token:
1452 keyword
1453 identifier
1454 constant
1455 string-literal
1456 punctuator
1457
1458 1.2) Keywords
1459
1460 keyword: is one of
1461
1462 align
1463 callsite
1464 const
1465 char
1466 clock
1467 double
1468 enum
1469 env
1470 event
1471 floating_point
1472 float
1473 integer
1474 int
1475 long
1476 short
1477 signed
1478 stream
1479 string
1480 struct
1481 trace
1482 typealias
1483 typedef
1484 unsigned
1485 variant
1486 void
1487 _Bool
1488 _Complex
1489 _Imaginary
1490
1491
1492 1.3) Identifiers
1493
1494 identifier:
1495 identifier-nondigit
1496 identifier identifier-nondigit
1497 identifier digit
1498
1499 identifier-nondigit:
1500 nondigit
1501 universal-character-name
1502 any other implementation-defined characters
1503
1504 nondigit:
1505 _
1506 [a-zA-Z] /* regular expression */
1507
1508 digit:
1509 [0-9] /* regular expression */
1510
1511 1.4) Universal character names
1512
1513 universal-character-name:
1514 \u hex-quad
1515 \U hex-quad hex-quad
1516
1517 hex-quad:
1518 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1519
1520 1.5) Constants
1521
1522 constant:
1523 integer-constant
1524 enumeration-constant
1525 character-constant
1526
1527 integer-constant:
1528 decimal-constant integer-suffix-opt
1529 octal-constant integer-suffix-opt
1530 hexadecimal-constant integer-suffix-opt
1531
1532 decimal-constant:
1533 nonzero-digit
1534 decimal-constant digit
1535
1536 octal-constant:
1537 0
1538 octal-constant octal-digit
1539
1540 hexadecimal-constant:
1541 hexadecimal-prefix hexadecimal-digit
1542 hexadecimal-constant hexadecimal-digit
1543
1544 hexadecimal-prefix:
1545 0x
1546 0X
1547
1548 nonzero-digit:
1549 [1-9]
1550
1551 integer-suffix:
1552 unsigned-suffix long-suffix-opt
1553 unsigned-suffix long-long-suffix
1554 long-suffix unsigned-suffix-opt
1555 long-long-suffix unsigned-suffix-opt
1556
1557 unsigned-suffix:
1558 u
1559 U
1560
1561 long-suffix:
1562 l
1563 L
1564
1565 long-long-suffix:
1566 ll
1567 LL
1568
1569 enumeration-constant:
1570 identifier
1571 string-literal
1572
1573 character-constant:
1574 ' c-char-sequence '
1575 L' c-char-sequence '
1576
1577 c-char-sequence:
1578 c-char
1579 c-char-sequence c-char
1580
1581 c-char:
1582 any member of source charset except single-quote ('), backslash
1583 (\), or new-line character.
1584 escape-sequence
1585
1586 escape-sequence:
1587 simple-escape-sequence
1588 octal-escape-sequence
1589 hexadecimal-escape-sequence
1590 universal-character-name
1591
1592 simple-escape-sequence: one of
1593 \' \" \? \\ \a \b \f \n \r \t \v
1594
1595 octal-escape-sequence:
1596 \ octal-digit
1597 \ octal-digit octal-digit
1598 \ octal-digit octal-digit octal-digit
1599
1600 hexadecimal-escape-sequence:
1601 \x hexadecimal-digit
1602 hexadecimal-escape-sequence hexadecimal-digit
1603
1604 1.6) String literals
1605
1606 string-literal:
1607 " s-char-sequence-opt "
1608 L" s-char-sequence-opt "
1609
1610 s-char-sequence:
1611 s-char
1612 s-char-sequence s-char
1613
1614 s-char:
1615 any member of source charset except double-quote ("), backslash
1616 (\), or new-line character.
1617 escape-sequence
1618
1619 1.7) Punctuators
1620
1621 punctuator: one of
1622 [ ] ( ) { } . -> * + - < > : ; ... = ,
1623
1624
1625 2) Phrase structure grammar
1626
1627 primary-expression:
1628 identifier
1629 constant
1630 string-literal
1631 ( unary-expression )
1632
1633 postfix-expression:
1634 primary-expression
1635 postfix-expression [ unary-expression ]
1636 postfix-expression . identifier
1637 postfix-expressoin -> identifier
1638
1639 unary-expression:
1640 postfix-expression
1641 unary-operator postfix-expression
1642
1643 unary-operator: one of
1644 + -
1645
1646 assignment-operator:
1647 =
1648
1649 type-assignment-operator:
1650 :=
1651
1652 constant-expression-range:
1653 unary-expression ... unary-expression
1654
1655 2.2) Declarations:
1656
1657 declaration:
1658 declaration-specifiers declarator-list-opt ;
1659 ctf-specifier ;
1660
1661 declaration-specifiers:
1662 storage-class-specifier declaration-specifiers-opt
1663 type-specifier declaration-specifiers-opt
1664 type-qualifier declaration-specifiers-opt
1665
1666 declarator-list:
1667 declarator
1668 declarator-list , declarator
1669
1670 abstract-declarator-list:
1671 abstract-declarator
1672 abstract-declarator-list , abstract-declarator
1673
1674 storage-class-specifier:
1675 typedef
1676
1677 type-specifier:
1678 void
1679 char
1680 short
1681 int
1682 long
1683 float
1684 double
1685 signed
1686 unsigned
1687 _Bool
1688 _Complex
1689 _Imaginary
1690 struct-specifier
1691 variant-specifier
1692 enum-specifier
1693 typedef-name
1694 ctf-type-specifier
1695
1696 align-attribute:
1697 align ( unary-expression )
1698
1699 struct-specifier:
1700 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1701 struct identifier align-attribute-opt
1702
1703 struct-or-variant-declaration-list:
1704 struct-or-variant-declaration
1705 struct-or-variant-declaration-list struct-or-variant-declaration
1706
1707 struct-or-variant-declaration:
1708 specifier-qualifier-list struct-or-variant-declarator-list ;
1709 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
1710 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1711 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
1712
1713 specifier-qualifier-list:
1714 type-specifier specifier-qualifier-list-opt
1715 type-qualifier specifier-qualifier-list-opt
1716
1717 struct-or-variant-declarator-list:
1718 struct-or-variant-declarator
1719 struct-or-variant-declarator-list , struct-or-variant-declarator
1720
1721 struct-or-variant-declarator:
1722 declarator
1723 declarator-opt : unary-expression
1724
1725 variant-specifier:
1726 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1727 variant identifier variant-tag
1728
1729 variant-tag:
1730 < unary-expression >
1731
1732 enum-specifier:
1733 enum identifier-opt { enumerator-list }
1734 enum identifier-opt { enumerator-list , }
1735 enum identifier
1736 enum identifier-opt : declaration-specifiers { enumerator-list }
1737 enum identifier-opt : declaration-specifiers { enumerator-list , }
1738
1739 enumerator-list:
1740 enumerator
1741 enumerator-list , enumerator
1742
1743 enumerator:
1744 enumeration-constant
1745 enumeration-constant assignment-operator unary-expression
1746 enumeration-constant assignment-operator constant-expression-range
1747
1748 type-qualifier:
1749 const
1750
1751 declarator:
1752 pointer-opt direct-declarator
1753
1754 direct-declarator:
1755 identifier
1756 ( declarator )
1757 direct-declarator [ unary-expression ]
1758
1759 abstract-declarator:
1760 pointer-opt direct-abstract-declarator
1761
1762 direct-abstract-declarator:
1763 identifier-opt
1764 ( abstract-declarator )
1765 direct-abstract-declarator [ unary-expression ]
1766 direct-abstract-declarator [ ]
1767
1768 pointer:
1769 * type-qualifier-list-opt
1770 * type-qualifier-list-opt pointer
1771
1772 type-qualifier-list:
1773 type-qualifier
1774 type-qualifier-list type-qualifier
1775
1776 typedef-name:
1777 identifier
1778
1779 2.3) CTF-specific declarations
1780
1781 ctf-specifier:
1782 clock { ctf-assignment-expression-list-opt }
1783 event { ctf-assignment-expression-list-opt }
1784 stream { ctf-assignment-expression-list-opt }
1785 env { ctf-assignment-expression-list-opt }
1786 trace { ctf-assignment-expression-list-opt }
1787 callsite { ctf-assignment-expression-list-opt }
1788 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1789 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
1790
1791 ctf-type-specifier:
1792 floating_point { ctf-assignment-expression-list-opt }
1793 integer { ctf-assignment-expression-list-opt }
1794 string { ctf-assignment-expression-list-opt }
1795 string
1796
1797 ctf-assignment-expression-list:
1798 ctf-assignment-expression ;
1799 ctf-assignment-expression-list ctf-assignment-expression ;
1800
1801 ctf-assignment-expression:
1802 unary-expression assignment-operator unary-expression
1803 unary-expression type-assignment-operator type-specifier
1804 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
1805 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1806 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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