4ab3ed99861b15af950a26d75722dcec382a2c12
[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 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 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 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 Even though the trace description section is not per se a type, for sake
185 of clarity, it should be noted that native and network byte orders are
186 only allowed within type declaration. The byte_order specified in the
187 trace description section only accepts be OR le values.
188
189 4.1.4 Size
190
191 Type size, in bits, for integers and floats is that returned by "sizeof()" in C
192 multiplied by CHAR_BIT.
193 We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
194 to 8 bits for cross-endianness compatibility.
195
196 TSDL meta-data representation:
197
198 size = value; (value is in bits)
199
200 4.1.5 Integers
201
202 Signed integers are represented in two-complement. Integer alignment,
203 size, signedness and byte ordering are defined in the TSDL meta-data.
204 Integers aligned on byte size (8-bit) and with length multiple of byte
205 size (8-bit) correspond to the C99 standard integers. In addition,
206 integers with alignment and/or size that are _not_ a multiple of the
207 byte size are permitted; these correspond to the C99 standard bitfields,
208 with the added specification that the CTF integer bitfields have a fixed
209 binary representation. A MIT-licensed reference implementation of the
210 CTF portable bitfields is available at:
211
212 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
213
214 Binary representation of integers:
215
216 - On little and big endian:
217 - Within a byte, high bits correspond to an integer high bits, and low bits
218 correspond to low bits.
219 - On little endian:
220 - Integer across multiple bytes are placed from the less significant to the
221 most significant.
222 - Consecutive integers are placed from lower bits to higher bits (even within
223 a byte).
224 - On big endian:
225 - Integer across multiple bytes are placed from the most significant to the
226 less significant.
227 - Consecutive integers are placed from higher bits to lower bits (even within
228 a byte).
229
230 This binary representation is derived from the bitfield implementation in GCC
231 for little and big endian. However, contrary to what GCC does, integers can
232 cross units boundaries (no padding is required). Padding can be explicitly
233 added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
234
235 TSDL meta-data representation:
236
237 integer {
238 signed = true OR false; /* default false */
239 byte_order = native OR network OR be OR le; /* default native */
240 size = value; /* value in bits, no default */
241 align = value; /* value in bits */
242 /* based used for pretty-printing output, default: decimal. */
243 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
244 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
245 /* character encoding, default: none */
246 encoding = none or UTF8 or ASCII;
247 }
248
249 Example of type inheritance (creation of a uint32_t named type):
250
251 typealias integer {
252 size = 32;
253 signed = false;
254 align = 32;
255 } := uint32_t;
256
257 Definition of a named 5-bit signed bitfield:
258
259 typealias integer {
260 size = 5;
261 signed = true;
262 align = 1;
263 } := int5_t;
264
265 The character encoding field can be used to specify that the integer
266 must be printed as a text character when read. e.g.:
267
268 typealias integer {
269 size = 8;
270 align = 8;
271 signed = false;
272 encoding = UTF8;
273 } := utf_char;
274
275
276 4.1.6 GNU/C bitfields
277
278 The GNU/C bitfields follow closely the integer representation, with a
279 particularity on alignment: if a bitfield cannot fit in the current unit, the
280 unit is padded and the bitfield starts at the following unit. The unit size is
281 defined by the size of the type "unit_type".
282
283 TSDL meta-data representation:
284
285 unit_type name:size;
286
287 As an example, the following structure declared in C compiled by GCC:
288
289 struct example {
290 short a:12;
291 short b:5;
292 };
293
294 The example structure is aligned on the largest element (short). The second
295 bitfield would be aligned on the next unit boundary, because it would not fit in
296 the current unit.
297
298 4.1.7 Floating point
299
300 The floating point values byte ordering is defined in the TSDL meta-data.
301
302 Floating point values follow the IEEE 754-2008 standard interchange formats.
303 Description of the floating point values include the exponent and mantissa size
304 in bits. Some requirements are imposed on the floating point values:
305
306 - FLT_RADIX must be 2.
307 - mant_dig is the number of digits represented in the mantissa. It is specified
308 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
309 LDBL_MANT_DIG as defined by <float.h>.
310 - exp_dig is the number of digits represented in the exponent. Given that
311 mant_dig is one bit more than its actual size in bits (leading 1 is not
312 needed) and also given that the sign bit always takes one bit, exp_dig can be
313 specified as:
314
315 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
316 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
317 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
318
319 TSDL meta-data representation:
320
321 floating_point {
322 exp_dig = value;
323 mant_dig = value;
324 byte_order = native OR network OR be OR le;
325 align = value;
326 }
327
328 Example of type inheritance:
329
330 typealias floating_point {
331 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
332 mant_dig = 24; /* FLT_MANT_DIG */
333 byte_order = native;
334 align = 32;
335 } := float;
336
337 TODO: define NaN, +inf, -inf behavior.
338
339 Bit-packed, byte-packed or larger alignments can be used for floating
340 point values, similarly to integers.
341
342 4.1.8 Enumerations
343
344 Enumerations are a mapping between an integer type and a table of strings. The
345 numerical representation of the enumeration follows the integer type specified
346 by the meta-data. The enumeration mapping table is detailed in the enumeration
347 description within the meta-data. The mapping table maps inclusive value
348 ranges (or single values) to strings. Instead of being limited to simple
349 "value -> string" mappings, these enumerations map
350 "[ start_value ... end_value ] -> string", which map inclusive ranges of
351 values to strings. An enumeration from the C language can be represented in
352 this format by having the same start_value and end_value for each element, which
353 is in fact a range of size 1. This single-value range is supported without
354 repeating the start and end values with the value = string declaration.
355
356 enum name : integer_type {
357 somestring = start_value1 ... end_value1,
358 "other string" = start_value2 ... end_value2,
359 yet_another_string, /* will be assigned to end_value2 + 1 */
360 "some other string" = value,
361 ...
362 };
363
364 If the values are omitted, the enumeration starts at 0 and increment of 1 for
365 each entry. An entry with omitted value that follows a range entry takes
366 as value the end_value of the previous range + 1:
367
368 enum name : unsigned int {
369 ZERO,
370 ONE,
371 TWO,
372 TEN = 10,
373 ELEVEN,
374 };
375
376 Overlapping ranges within a single enumeration are implementation defined.
377
378 A nameless enumeration can be declared as a field type or as part of a typedef:
379
380 enum : integer_type {
381 ...
382 }
383
384 Enumerations omitting the container type ": integer_type" use the "int"
385 type (for compatibility with C99). The "int" type must be previously
386 declared. E.g.:
387
388 typealias integer { size = 32; align = 32; signed = true } := int;
389
390 enum {
391 ...
392 }
393
394
395 4.2 Compound types
396
397 Compound are aggregation of type declarations. Compound types include
398 structures, variant, arrays, sequences, and strings.
399
400 4.2.1 Structures
401
402 Structures are aligned on the largest alignment required by basic types
403 contained within the structure. (This follows the ISO/C standard for structures)
404
405 TSDL meta-data representation of a named structure:
406
407 struct name {
408 field_type field_name;
409 field_type field_name;
410 ...
411 };
412
413 Example:
414
415 struct example {
416 integer { /* Nameless type */
417 size = 16;
418 signed = true;
419 align = 16;
420 } first_field_name;
421 uint64_t second_field_name; /* Named type declared in the meta-data */
422 };
423
424 The fields are placed in a sequence next to each other. They each
425 possess a field name, which is a unique identifier within the structure.
426 The identifier is not allowed to use any reserved keyword
427 (see Section C.1.2). Replacing reserved keywords with
428 underscore-prefixed field names is recommended. Fields starting with an
429 underscore should have their leading underscore removed by the CTF trace
430 readers.
431
432 A nameless structure can be declared as a field type or as part of a typedef:
433
434 struct {
435 ...
436 }
437
438 Alignment for a structure compound type can be forced to a minimum value
439 by adding an "align" specifier after the declaration of a structure
440 body. This attribute is read as: align(value). The value is specified in
441 bits. The structure will be aligned on the maximum value between this
442 attribute and the alignment required by the basic types contained within
443 the structure. e.g.
444
445 struct {
446 ...
447 } align(32)
448
449 4.2.2 Variants (Discriminated/Tagged Unions)
450
451 A CTF variant is a selection between different types. A CTF variant must
452 always be defined within the scope of a structure or within fields
453 contained within a structure (defined recursively). A "tag" enumeration
454 field must appear in either the same static scope, prior to the variant
455 field (in field declaration order), in an upper static scope , or in an
456 upper dynamic scope (see Section 7.3.2). The type selection is indicated
457 by the mapping from the enumeration value to the string used as variant
458 type selector. The field to use as tag is specified by the "tag_field",
459 specified between "< >" after the "variant" keyword for unnamed
460 variants, and after "variant name" for named variants.
461
462 The alignment of the variant is the alignment of the type as selected by
463 the tag value for the specific instance of the variant. The size of the
464 variant is the size as selected by the tag value for the specific
465 instance of the variant.
466
467 The alignment of the type containing the variant is independent of the
468 variant alignment. For instance, if a structure contains two fields, a
469 32-bit integer, aligned on 32 bits, and a variant, which contains two
470 choices: either a 32-bit field, aligned on 32 bits, or a 64-bit field,
471 aligned on 64 bits, the alignment of the outmost structure will be
472 32-bit (the alignment of its largest field, disregarding the alignment
473 of the variant). The alignment of the variant will depend on the
474 selector: if the variant's 32-bit field is selected, its alignment will
475 be 32-bit, or 64-bit otherwise. It is important to note that variants
476 are specifically tailored for compactness in a stream. Therefore, the
477 relative offsets of compound type fields can vary depending on
478 the offset at which the compound type starts if it contains a variant
479 that itself contains a type with alignment larger than the largest field
480 contained within the compound type. This is caused by the fact that the
481 compound type may contain the enumeration that select the variant's
482 choice, and therefore the alignment to be applied to the compound type
483 cannot be determined before encountering the enumeration.
484
485 Each variant type selector possess a field name, which is a unique
486 identifier within the variant. The identifier is not allowed to use any
487 reserved keyword (see Section C.1.2). Replacing reserved keywords with
488 underscore-prefixed field names is recommended. Fields starting with an
489 underscore should have their leading underscore removed by the CTF trace
490 readers.
491
492
493 A named variant declaration followed by its definition within a structure
494 declaration:
495
496 variant name {
497 field_type sel1;
498 field_type sel2;
499 field_type sel3;
500 ...
501 };
502
503 struct {
504 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
505 ...
506 variant name <tag_field> v;
507 }
508
509 An unnamed variant definition within a structure is expressed by the following
510 TSDL meta-data:
511
512 struct {
513 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
514 ...
515 variant <tag_field> {
516 field_type sel1;
517 field_type sel2;
518 field_type sel3;
519 ...
520 } v;
521 }
522
523 Example of a named variant within a sequence that refers to a single tag field:
524
525 variant example {
526 uint32_t a;
527 uint64_t b;
528 short c;
529 };
530
531 struct {
532 enum : uint2_t { a, b, c } choice;
533 unsigned int seqlen;
534 variant example <choice> v[seqlen];
535 }
536
537 Example of an unnamed variant:
538
539 struct {
540 enum : uint2_t { a, b, c, d } choice;
541 /* Unrelated fields can be added between the variant and its tag */
542 int32_t somevalue;
543 variant <choice> {
544 uint32_t a;
545 uint64_t b;
546 short c;
547 struct {
548 unsigned int field1;
549 uint64_t field2;
550 } d;
551 } s;
552 }
553
554 Example of an unnamed variant within an array:
555
556 struct {
557 enum : uint2_t { a, b, c } choice;
558 variant <choice> {
559 uint32_t a;
560 uint64_t b;
561 short c;
562 } v[10];
563 }
564
565 Example of a variant type definition within a structure, where the defined type
566 is then declared within an array of structures. This variant refers to a tag
567 located in an upper static scope. This example clearly shows that a variant
568 type definition referring to the tag "x" uses the closest preceding field from
569 the static scope of the type definition.
570
571 struct {
572 enum : uint2_t { a, b, c, d } x;
573
574 typedef variant <x> { /*
575 * "x" refers to the preceding "x" enumeration in the
576 * static scope of the type definition.
577 */
578 uint32_t a;
579 uint64_t b;
580 short c;
581 } example_variant;
582
583 struct {
584 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
585 example_variant v; /*
586 * "v" uses the "enum : uint2_t { a, b, c, d }"
587 * tag.
588 */
589 } a[10];
590 }
591
592 4.2.3 Arrays
593
594 Arrays are fixed-length. Their length is declared in the type
595 declaration within the meta-data. They contain an array of "inner type"
596 elements, which can refer to any type not containing the type of the
597 array being declared (no circular dependency). The length is the number
598 of elements in an array.
599
600 TSDL meta-data representation of a named array:
601
602 typedef elem_type name[length];
603
604 A nameless array can be declared as a field type within a structure, e.g.:
605
606 uint8_t field_name[10];
607
608 Arrays are always aligned on their element alignment requirement.
609
610 4.2.4 Sequences
611
612 Sequences are dynamically-sized arrays. They refer to a "length"
613 unsigned integer field, which must appear in either the same static scope,
614 prior to the sequence field (in field declaration order), in an upper
615 static scope, or in an upper dynamic scope (see Section 7.3.2). This
616 length field represents the number of elements in the sequence. The
617 sequence per se is an array of "inner type" elements.
618
619 TSDL meta-data representation for a sequence type definition:
620
621 struct {
622 unsigned int length_field;
623 typedef elem_type typename[length_field];
624 typename seq_field_name;
625 }
626
627 A sequence can also be declared as a field type, e.g.:
628
629 struct {
630 unsigned int length_field;
631 long seq_field_name[length_field];
632 }
633
634 Multiple sequences can refer to the same length field, and these length
635 fields can be in a different upper dynamic scope:
636
637 e.g., assuming the stream.event.header defines:
638
639 stream {
640 ...
641 id = 1;
642 event.header := struct {
643 uint16_t seq_len;
644 };
645 };
646
647 event {
648 ...
649 stream_id = 1;
650 fields := struct {
651 long seq_a[stream.event.header.seq_len];
652 char seq_b[stream.event.header.seq_len];
653 };
654 };
655
656 The sequence elements follow the "array" specifications.
657
658 4.2.5 Strings
659
660 Strings are an array of bytes of variable size and are terminated by a '\0'
661 "NULL" character. Their encoding is described in the TSDL meta-data. In
662 absence of encoding attribute information, the default encoding is
663 UTF-8.
664
665 TSDL meta-data representation of a named string type:
666
667 typealias string {
668 encoding = UTF8 OR ASCII;
669 } := name;
670
671 A nameless string type can be declared as a field type:
672
673 string field_name; /* Use default UTF8 encoding */
674
675 Strings are always aligned on byte size.
676
677 5. Event Packet Header
678
679 The event packet header consists of two parts: the "event packet header"
680 is the same for all streams of a trace. The second part, the "event
681 packet context", is described on a per-stream basis. Both are described
682 in the TSDL meta-data. The packets are aligned on architecture-page-sized
683 addresses.
684
685 Event packet header (all fields are optional, specified by TSDL meta-data):
686
687 - Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
688 CTF packet. This magic number is optional, but when present, it should
689 come at the very beginning of the packet.
690 - Trace UUID, used to ensure the event packet match the meta-data used.
691 (note: we cannot use a meta-data checksum in every cases instead of a
692 UUID because meta-data can be appended to while tracing is active)
693 This field is optional.
694 - Stream ID, used as reference to stream description in meta-data.
695 This field is optional if there is only one stream description in the
696 meta-data, but becomes required if there are more than one stream in
697 the TSDL meta-data description.
698
699 Event packet context (all fields are optional, specified by TSDL meta-data):
700
701 - Event packet content size (in bits).
702 - Event packet size (in bits, includes padding).
703 - Event packet content checksum. Checksum excludes the event packet
704 header.
705 - Per-stream event packet sequence count (to deal with UDP packet loss). The
706 number of significant sequence counter bits should also be present, so
707 wrap-arounds are dealt with correctly.
708 - Time-stamp at the beginning and time-stamp at the end of the event packet.
709 Both timestamps are written in the packet header, but sampled respectively
710 while (or before) writing the first event and while (or after) writing the
711 last event in the packet. The inclusive range between these timestamps should
712 include all event timestamps assigned to events contained within the packet.
713 - Events discarded count
714 - Snapshot of a per-stream free-running counter, counting the number of
715 events discarded that were supposed to be written in the stream after
716 the last event in the event packet.
717 * Note: producer-consumer buffer full condition can fill the current
718 event packet with padding so we know exactly where events have been
719 discarded. However, if the buffer full condition chooses not
720 to fill the current event packet with padding, all we know
721 about the timestamp range in which the events have been
722 discarded is that it is somewhere between the beginning and
723 the end of the packet.
724 - Lossless compression scheme used for the event packet content. Applied
725 directly to raw data. New types of compression can be added in following
726 versions of the format.
727 0: no compression scheme
728 1: bzip2
729 2: gzip
730 3: xz
731 - Cypher used for the event packet content. Applied after compression.
732 0: no encryption
733 1: AES
734 - Checksum scheme used for the event packet content. Applied after encryption.
735 0: no checksum
736 1: md5
737 2: sha1
738 3: crc32
739
740 5.1 Event Packet Header Description
741
742 The event packet header layout is indicated by the trace packet.header
743 field. Here is a recommended structure type for the packet header with
744 the fields typically expected (although these fields are each optional):
745
746 struct event_packet_header {
747 uint32_t magic;
748 uint8_t uuid[16];
749 uint32_t stream_id;
750 };
751
752 trace {
753 ...
754 packet.header := struct event_packet_header;
755 };
756
757 If the magic number is not present, tools such as "file" will have no
758 mean to discover the file type.
759
760 If the uuid is not present, no validation that the meta-data actually
761 corresponds to the stream is performed.
762
763 If the stream_id packet header field is missing, the trace can only
764 contain a single stream. Its "id" field can be left out, and its events
765 don't need to declare a "stream_id" field.
766
767
768 5.2 Event Packet Context Description
769
770 Event packet context example. These are declared within the stream declaration
771 in the meta-data. All these fields are optional. If the packet size field is
772 missing, the whole stream only contains a single packet. If the content
773 size field is missing, the packet is filled (no padding). The content
774 and packet sizes include all headers.
775
776 An example event packet context type:
777
778 struct event_packet_context {
779 uint64_t timestamp_begin;
780 uint64_t timestamp_end;
781 uint32_t checksum;
782 uint32_t stream_packet_count;
783 uint32_t events_discarded;
784 uint32_t cpu_id;
785 uint64_t/uint32_t/uint16_t content_size;
786 uint64_t/uint32_t/uint16_t packet_size;
787 uint8_t compression_scheme;
788 uint8_t encryption_scheme;
789 uint8_t checksum_scheme;
790 };
791
792
793 6. Event Structure
794
795 The overall structure of an event is:
796
797 1 - Stream Packet Context (as specified by the stream meta-data)
798 2 - Event Header (as specified by the stream meta-data)
799 3 - Stream Event Context (as specified by the stream meta-data)
800 4 - Event Context (as specified by the event meta-data)
801 5 - Event Payload (as specified by the event meta-data)
802
803 This structure defines an implicit dynamic scoping, where variants
804 located in inner structures (those with a higher number in the listing
805 above) can refer to the fields of outer structures (with lower number in
806 the listing above). See Section 7.3 TSDL Scopes for more detail.
807
808 6.1 Event Header
809
810 Event headers can be described within the meta-data. We hereby propose, as an
811 example, two types of events headers. Type 1 accommodates streams with less than
812 31 event IDs. Type 2 accommodates streams with 31 or more event IDs.
813
814 One major factor can vary between streams: the number of event IDs assigned to
815 a stream. Luckily, this information tends to stay relatively constant (modulo
816 event registration while trace is being recorded), so we can specify different
817 representations for streams containing few event IDs and streams containing
818 many event IDs, so we end up representing the event ID and time-stamp as
819 densely as possible in each case.
820
821 The header is extended in the rare occasions where the information cannot be
822 represented in the ranges available in the standard event header. They are also
823 used in the rare occasions where the data required for a field could not be
824 collected: the flag corresponding to the missing field within the missing_fields
825 array is then set to 1.
826
827 Types uintX_t represent an X-bit unsigned integer, as declared with
828 either:
829
830 typealias integer { size = X; align = X; signed = false } := uintX_t;
831
832 or
833
834 typealias integer { size = X; align = 1; signed = false } := uintX_t;
835
836 6.1.1 Type 1 - Few event IDs
837
838 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
839 preference).
840 - Native architecture byte ordering.
841 - For "compact" selection
842 - Fixed size: 32 bits.
843 - For "extended" selection
844 - Size depends on the architecture and variant alignment.
845
846 struct event_header_1 {
847 /*
848 * id: range: 0 - 30.
849 * id 31 is reserved to indicate an extended header.
850 */
851 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
852 variant <id> {
853 struct {
854 uint27_t timestamp;
855 } compact;
856 struct {
857 uint32_t id; /* 32-bit event IDs */
858 uint64_t timestamp; /* 64-bit timestamps */
859 } extended;
860 } v;
861 } align(32); /* or align(8) */
862
863
864 6.1.2 Type 2 - Many event IDs
865
866 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
867 preference).
868 - Native architecture byte ordering.
869 - For "compact" selection
870 - Size depends on the architecture and variant alignment.
871 - For "extended" selection
872 - Size depends on the architecture and variant alignment.
873
874 struct event_header_2 {
875 /*
876 * id: range: 0 - 65534.
877 * id 65535 is reserved to indicate an extended header.
878 */
879 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
880 variant <id> {
881 struct {
882 uint32_t timestamp;
883 } compact;
884 struct {
885 uint32_t id; /* 32-bit event IDs */
886 uint64_t timestamp; /* 64-bit timestamps */
887 } extended;
888 } v;
889 } align(16); /* or align(8) */
890
891
892 6.2 Event Context
893
894 The event context contains information relative to the current event.
895 The choice and meaning of this information is specified by the TSDL
896 stream and event meta-data descriptions. The stream context is applied
897 to all events within the stream. The stream context structure follows
898 the event header. The event context is applied to specific events. Its
899 structure follows the stream context structure.
900
901 An example of stream-level event context is to save the event payload size with
902 each event, or to save the current PID with each event. These are declared
903 within the stream declaration within the meta-data:
904
905 stream {
906 ...
907 event.context := struct {
908 uint pid;
909 uint16_t payload_size;
910 };
911 };
912
913 An example of event-specific event context is to declare a bitmap of missing
914 fields, only appended after the stream event context if the extended event
915 header is selected. NR_FIELDS is the number of fields within the event (a
916 numeric value).
917
918 event {
919 context = struct {
920 variant <id> {
921 struct { } compact;
922 struct {
923 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
924 } extended;
925 } v;
926 };
927 ...
928 }
929
930 6.3 Event Payload
931
932 An event payload contains fields specific to a given event type. The fields
933 belonging to an event type are described in the event-specific meta-data
934 within a structure type.
935
936 6.3.1 Padding
937
938 No padding at the end of the event payload. This differs from the ISO/C standard
939 for structures, but follows the CTF standard for structures. In a trace, even
940 though it makes sense to align the beginning of a structure, it really makes no
941 sense to add padding at the end of the structure, because structures are usually
942 not followed by a structure of the same type.
943
944 This trick can be done by adding a zero-length "end" field at the end of the C
945 structures, and by using the offset of this field rather than using sizeof()
946 when calculating the size of a structure (see Appendix "A. Helper macros").
947
948 6.3.2 Alignment
949
950 The event payload is aligned on the largest alignment required by types
951 contained within the payload. (This follows the ISO/C standard for structures)
952
953
954 7. Trace Stream Description Language (TSDL)
955
956 The Trace Stream Description Language (TSDL) allows expression of the
957 binary trace streams layout in a C99-like Domain Specific Language
958 (DSL).
959
960
961 7.1 Meta-data
962
963 The trace stream layout description is located in the trace meta-data.
964 The meta-data is itself located in a stream identified by its name:
965 "metadata".
966
967 The meta-data description can be expressed in two different formats:
968 text-only and packet-based. The text-only description facilitates
969 generation of meta-data and provides a convenient way to enter the
970 meta-data information by hand. The packet-based meta-data provides the
971 CTF stream packet facilities (checksumming, compression, encryption,
972 network-readiness) for meta-data stream generated and transported by a
973 tracer.
974
975 The text-only meta-data file is a plain-text TSDL description. This file
976 must begin with the following characters to identify the file as a CTF
977 TSDL text-based metadata file (without the double-quotes) :
978
979 "/* CTF"
980
981 It must be followed by a space, and the version of the specification
982 followed by the CTF trace, e.g.:
983
984 " 1.8"
985
986 These characters allow automated discovery of file type and CTF
987 specification version. They are interpreted as a the beginning of a
988 comment by the TSDL metadata parser. The comment can be continued to
989 contain extra commented characters before it is closed.
990
991 The packet-based meta-data is made of "meta-data packets", which each
992 start with a meta-data packet header. The packet-based meta-data
993 description is detected by reading the magic number "0x75D11D57" at the
994 beginning of the file. This magic number is also used to detect the
995 endianness of the architecture by trying to read the CTF magic number
996 and its counterpart in reversed endianness. The events within the
997 meta-data stream have no event header nor event context. Each event only
998 contains a special "sequence" payload, which is a sequence of bits which
999 length is implicitly calculated by using the
1000 "trace.packet.header.content_size" field, minus the packet header size.
1001 The formatting of this sequence of bits is a plain-text representation
1002 of the TSDL description. Each meta-data packet start with a special
1003 packet header, specific to the meta-data stream, which contains,
1004 exactly:
1005
1006 struct metadata_packet_header {
1007 uint32_t magic; /* 0x75D11D57 */
1008 uint8_t uuid[16]; /* Unique Universal Identifier */
1009 uint32_t checksum; /* 0 if unused */
1010 uint32_t content_size; /* in bits */
1011 uint32_t packet_size; /* in bits */
1012 uint8_t compression_scheme; /* 0 if unused */
1013 uint8_t encryption_scheme; /* 0 if unused */
1014 uint8_t checksum_scheme; /* 0 if unused */
1015 uint8_t major; /* CTF spec version major number */
1016 uint8_t minor; /* CTF spec version minor number */
1017 };
1018
1019 The packet-based meta-data can be converted to a text-only meta-data by
1020 concatenating all the strings it contains.
1021
1022 In the textual representation of the meta-data, the text contained
1023 within "/*" and "*/", as well as within "//" and end of line, are
1024 treated as comments. Boolean values can be represented as true, TRUE,
1025 or 1 for true, and false, FALSE, or 0 for false. Within the string-based
1026 meta-data description, the trace UUID is represented as a string of
1027 hexadecimal digits and dashes "-". In the event packet header, the trace
1028 UUID is represented as an array of bytes.
1029
1030
1031 7.2 Declaration vs Definition
1032
1033 A declaration associates a layout to a type, without specifying where
1034 this type is located in the event structure hierarchy (see Section 6).
1035 This therefore includes typedef, typealias, as well as all type
1036 specifiers. In certain circumstances (typedef, structure field and
1037 variant field), a declaration is followed by a declarator, which specify
1038 the newly defined type name (for typedef), or the field name (for
1039 declarations located within structure and variants). Array and sequence,
1040 declared with square brackets ("[" "]"), are part of the declarator,
1041 similarly to C99. The enumeration base type is specified by
1042 ": enum_base", which is part of the type specifier. The variant tag
1043 name, specified between "<" ">", is also part of the type specifier.
1044
1045 A definition associates a type to a location in the event structure
1046 hierarchy (see Section 6). This association is denoted by ":=", as shown
1047 in Section 7.3.
1048
1049
1050 7.3 TSDL Scopes
1051
1052 TSDL uses three different types of scoping: a lexical scope is used for
1053 declarations and type definitions, and static and dynamic scopes are
1054 used for variants references to tag fields (with relative and absolute
1055 path lookups) and for sequence references to length fields.
1056
1057 7.3.1 Lexical Scope
1058
1059 Each of "trace", "env", "stream", "event", "struct" and "variant" have
1060 their own nestable declaration scope, within which types can be declared
1061 using "typedef" and "typealias". A root declaration scope also contains
1062 all declarations located outside of any of the aforementioned
1063 declarations. An inner declaration scope can refer to type declared
1064 within its container lexical scope prior to the inner declaration scope.
1065 Redefinition of a typedef or typealias is not valid, although hiding an
1066 upper scope typedef or typealias is allowed within a sub-scope.
1067
1068 7.3.2 Static and Dynamic Scopes
1069
1070 A local static scope consists in the scope generated by the declaration
1071 of fields within a compound type. A static scope is a local static scope
1072 augmented with the nested sub-static-scopes it contains.
1073
1074 A dynamic scope consists in the static scope augmented with the
1075 implicit event structure definition hierarchy presented at Section 6.
1076
1077 Multiple declarations of the same field name within a local static scope
1078 is not valid. It is however valid to re-use the same field name in
1079 different local scopes.
1080
1081 Nested static and dynamic scopes form lookup paths. These are used for
1082 variant tag and sequence length references. They are used at the variant
1083 and sequence definition site to look up the location of the tag field
1084 associated with a variant, and to lookup up the location of the length
1085 field associated with a sequence.
1086
1087 Variants and sequences can refer to a tag field either using a relative
1088 path or an absolute path. The relative path is relative to the scope in
1089 which the variant or sequence performing the lookup is located.
1090 Relative paths are only allowed to lookup within the same static scope,
1091 which includes its nested static scopes. Lookups targeting parent static
1092 scopes need to be performed with an absolute path.
1093
1094 Absolute path lookups use the full path including the dynamic scope
1095 followed by a "." and then the static scope. Therefore, variants (or
1096 sequences) in lower levels in the dynamic scope (e.g. event context) can
1097 refer to a tag (or length) field located in upper levels (e.g. in the
1098 event header) by specifying, in this case, the associated tag with
1099 <stream.event.header.field_name>. This allows, for instance, the event
1100 context to define a variant referring to the "id" field of the event
1101 header as selector.
1102
1103 The dynamic scope prefixes are thus:
1104
1105 - Trace Environment: <env. >,
1106 - Trace Packet Header: <trace.packet.header. >,
1107 - Stream Packet Context: <stream.packet.context. >,
1108 - Event Header: <stream.event.header. >,
1109 - Stream Event Context: <stream.event.context. >,
1110 - Event Context: <event.context. >,
1111 - Event Payload: <event.fields. >.
1112
1113
1114 The target dynamic scope must be specified explicitly when referring to
1115 a field outside of the static scope (absolute scope reference). No
1116 conflict can occur between relative and dynamic paths, because the
1117 keywords "trace", "stream", and "event" are reserved, and thus
1118 not permitted as field names. It is recommended that field names
1119 clashing with CTF and C99 reserved keywords use an underscore prefix to
1120 eliminate the risk of generating a description containing an invalid
1121 field name. Consequently, fields starting with an underscore should have
1122 their leading underscore removed by the CTF trace readers.
1123
1124
1125 The information available in the dynamic scopes can be thought of as the
1126 current tracing context. At trace production, information about the
1127 current context is saved into the specified scope field levels. At trace
1128 consumption, for each event, the current trace context is therefore
1129 readable by accessing the upper dynamic scopes.
1130
1131
1132 7.4 TSDL Examples
1133
1134 The grammar representing the TSDL meta-data is presented in Appendix C.
1135 TSDL Grammar. This section presents a rather lighter reading that
1136 consists in examples of TSDL meta-data, with template values.
1137
1138 The stream "id" can be left out if there is only one stream in the
1139 trace. The event "id" field can be left out if there is only one event
1140 in a stream.
1141
1142 trace {
1143 major = value; /* CTF spec version major number */
1144 minor = value; /* CTF spec version minor number */
1145 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
1146 byte_order = be OR le; /* Endianness (required) */
1147 packet.header := struct {
1148 uint32_t magic;
1149 uint8_t uuid[16];
1150 uint32_t stream_id;
1151 };
1152 };
1153
1154 /*
1155 * The "env" (environment) scope contains assignment expressions. The
1156 * field names and content are implementation-defined.
1157 */
1158 env {
1159 pid = value; /* example */
1160 proc_name = "name"; /* example */
1161 ...
1162 };
1163
1164 stream {
1165 id = stream_id;
1166 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
1167 event.header := event_header_1 OR event_header_2;
1168 event.context := struct {
1169 ...
1170 };
1171 packet.context := struct {
1172 ...
1173 };
1174 };
1175
1176 event {
1177 name = "event_name";
1178 id = value; /* Numeric identifier within the stream */
1179 stream_id = stream_id;
1180 loglevel = value;
1181 model.emf.uri = "string";
1182 context := struct {
1183 ...
1184 };
1185 fields := struct {
1186 ...
1187 };
1188 };
1189
1190 callsite {
1191 name = "event_name";
1192 func = "func_name";
1193 file = "myfile.c";
1194 line = 39;
1195 ip = 0x40096c;
1196 };
1197
1198 /* More detail on types in section 4. Types */
1199
1200 /*
1201 * Named types:
1202 *
1203 * Type declarations behave similarly to the C standard.
1204 */
1205
1206 typedef aliased_type_specifiers new_type_declarators;
1207
1208 /* e.g.: typedef struct example new_type_name[10]; */
1209
1210 /*
1211 * typealias
1212 *
1213 * The "typealias" declaration can be used to give a name (including
1214 * pointer declarator specifier) to a type. It should also be used to
1215 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1216 * Typealias is a superset of "typedef": it also allows assignment of a
1217 * simple variable identifier to a type.
1218 */
1219
1220 typealias type_class {
1221 ...
1222 } := type_specifiers type_declarator;
1223
1224 /*
1225 * e.g.:
1226 * typealias integer {
1227 * size = 32;
1228 * align = 32;
1229 * signed = false;
1230 * } := struct page *;
1231 *
1232 * typealias integer {
1233 * size = 32;
1234 * align = 32;
1235 * signed = true;
1236 * } := int;
1237 */
1238
1239 struct name {
1240 ...
1241 };
1242
1243 variant name {
1244 ...
1245 };
1246
1247 enum name : integer_type {
1248 ...
1249 };
1250
1251
1252 /*
1253 * Unnamed types, contained within compound type fields, typedef or typealias.
1254 */
1255
1256 struct {
1257 ...
1258 }
1259
1260 struct {
1261 ...
1262 } align(value)
1263
1264 variant {
1265 ...
1266 }
1267
1268 enum : integer_type {
1269 ...
1270 }
1271
1272 typedef type new_type[length];
1273
1274 struct {
1275 type field_name[length];
1276 }
1277
1278 typedef type new_type[length_type];
1279
1280 struct {
1281 type field_name[length_type];
1282 }
1283
1284 integer {
1285 ...
1286 }
1287
1288 floating_point {
1289 ...
1290 }
1291
1292 struct {
1293 integer_type field_name:size; /* GNU/C bitfield */
1294 }
1295
1296 struct {
1297 string field_name;
1298 }
1299
1300
1301 8. Clocks
1302
1303 Clock metadata allows to describe the clock topology of the system, as
1304 well as to detail each clock parameter. In absence of clock description,
1305 it is assumed that all fields named "timestamp" use the same clock
1306 source, which increments once per nanosecond.
1307
1308 Describing a clock and how it is used by streams is threefold: first,
1309 the clock and clock topology should be described in a "clock"
1310 description block, e.g.:
1311
1312 clock {
1313 name = cycle_counter_sync;
1314 uuid = "62189bee-96dc-11e0-91a8-cfa3d89f3923";
1315 description = "Cycle counter synchronized across CPUs";
1316 freq = 1000000000; /* frequency, in Hz */
1317 /* precision in seconds is: 1000 * (1/freq) */
1318 precision = 1000;
1319 /*
1320 * clock value offset from Epoch is:
1321 * offset_s + (offset * (1/freq))
1322 */
1323 offset_s = 1326476837;
1324 offset = 897235420;
1325 absolute = FALSE;
1326 };
1327
1328 The mandatory "name" field specifies the name of the clock identifier,
1329 which can later be used as a reference. The optional field "uuid" is the
1330 unique identifier of the clock. It can be used to correlate different
1331 traces that use the same clock. An optional textual description string
1332 can be added with the "description" field. The "freq" field is the
1333 initial frequency of the clock, in Hz. If the "freq" field is not
1334 present, the frequency is assumed to be 1000000000 (providing clock
1335 increment of 1 ns). The optional "precision" field details the
1336 uncertainty on the clock measurements, in (1/freq) units. The "offset_s"
1337 and "offset" fields indicate the offset from POSIX.1 Epoch, 1970-01-01
1338 00:00:00 +0000 (UTC), to the zero of value of the clock. The "offset_s"
1339 field is in seconds. The "offset" field is in (1/freq) units. If any of
1340 the "offset_s" or "offset" field is not present, it is assigned the 0
1341 value. The field "absolute" is TRUE if the clock is a global reference
1342 across different clock uuid (e.g. NTP time). Otherwise, "absolute" is
1343 FALSE, and the clock can be considered as synchronized only with other
1344 clocks that have the same uuid.
1345
1346
1347 Secondly, a reference to this clock should be added within an integer
1348 type:
1349
1350 typealias integer {
1351 size = 64; align = 1; signed = false;
1352 map = clock.cycle_counter_sync.value;
1353 } := uint64_ccnt_t;
1354
1355 Thirdly, stream declarations can reference the clock they use as a
1356 time-stamp source:
1357
1358 struct packet_context {
1359 uint64_ccnt_t ccnt_begin;
1360 uint64_ccnt_t ccnt_end;
1361 /* ... */
1362 };
1363
1364 stream {
1365 /* ... */
1366 event.header := struct {
1367 uint64_ccnt_t timestamp;
1368 /* ... */
1369 }
1370 packet.context := struct packet_context;
1371 };
1372
1373 For a N-bit integer type referring to a clock, if the integer overflows
1374 compared to the N low order bits of the clock prior value, then it is
1375 assumed that one, and only one, overflow occurred. It is therefore
1376 important that events encoding time on a small number of bits happen
1377 frequently enough to detect when more than one N-bit overflow occurs.
1378
1379 In a packet context, clock field names ending with "_begin" and "_end"
1380 have a special meaning: this refers to the time-stamps at, respectively,
1381 the beginning and the end of each packet.
1382
1383
1384 A. Helper macros
1385
1386 The two following macros keep track of the size of a GNU/C structure without
1387 padding at the end by placing HEADER_END as the last field. A one byte end field
1388 is used for C90 compatibility (C99 flexible arrays could be used here). Note
1389 that this does not affect the effective structure size, which should always be
1390 calculated with the header_sizeof() helper.
1391
1392 #define HEADER_END char end_field
1393 #define header_sizeof(type) offsetof(typeof(type), end_field)
1394
1395
1396 B. Stream Header Rationale
1397
1398 An event stream is divided in contiguous event packets of variable size. These
1399 subdivisions allow the trace analyzer to perform a fast binary search by time
1400 within the stream (typically requiring to index only the event packet headers)
1401 without reading the whole stream. These subdivisions have a variable size to
1402 eliminate the need to transfer the event packet padding when partially filled
1403 event packets must be sent when streaming a trace for live viewing/analysis.
1404 An event packet can contain a certain amount of padding at the end. Dividing
1405 streams into event packets is also useful for network streaming over UDP and
1406 flight recorder mode tracing (a whole event packet can be swapped out of the
1407 buffer atomically for reading).
1408
1409 The stream header is repeated at the beginning of each event packet to allow
1410 flexibility in terms of:
1411
1412 - streaming support,
1413 - allowing arbitrary buffers to be discarded without making the trace
1414 unreadable,
1415 - allow UDP packet loss handling by either dealing with missing event packet
1416 or asking for re-transmission.
1417 - transparently support flight recorder mode,
1418 - transparently support crash dump.
1419
1420
1421 C. TSDL Grammar
1422
1423 /*
1424 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
1425 *
1426 * Inspired from the C99 grammar:
1427 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
1428 * and c++1x grammar (draft)
1429 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
1430 *
1431 * Specialized for CTF needs by including only constant and declarations from
1432 * C99 (excluding function declarations), and by adding support for variants,
1433 * sequences and CTF-specific specifiers. Enumeration container types
1434 * semantic is inspired from c++1x enum-base.
1435 */
1436
1437 1) Lexical grammar
1438
1439 1.1) Lexical elements
1440
1441 token:
1442 keyword
1443 identifier
1444 constant
1445 string-literal
1446 punctuator
1447
1448 1.2) Keywords
1449
1450 keyword: is one of
1451
1452 align
1453 callsite
1454 const
1455 char
1456 clock
1457 double
1458 enum
1459 env
1460 event
1461 floating_point
1462 float
1463 integer
1464 int
1465 long
1466 short
1467 signed
1468 stream
1469 string
1470 struct
1471 trace
1472 typealias
1473 typedef
1474 unsigned
1475 variant
1476 void
1477 _Bool
1478 _Complex
1479 _Imaginary
1480
1481
1482 1.3) Identifiers
1483
1484 identifier:
1485 identifier-nondigit
1486 identifier identifier-nondigit
1487 identifier digit
1488
1489 identifier-nondigit:
1490 nondigit
1491 universal-character-name
1492 any other implementation-defined characters
1493
1494 nondigit:
1495 _
1496 [a-zA-Z] /* regular expression */
1497
1498 digit:
1499 [0-9] /* regular expression */
1500
1501 1.4) Universal character names
1502
1503 universal-character-name:
1504 \u hex-quad
1505 \U hex-quad hex-quad
1506
1507 hex-quad:
1508 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1509
1510 1.5) Constants
1511
1512 constant:
1513 integer-constant
1514 enumeration-constant
1515 character-constant
1516
1517 integer-constant:
1518 decimal-constant integer-suffix-opt
1519 octal-constant integer-suffix-opt
1520 hexadecimal-constant integer-suffix-opt
1521
1522 decimal-constant:
1523 nonzero-digit
1524 decimal-constant digit
1525
1526 octal-constant:
1527 0
1528 octal-constant octal-digit
1529
1530 hexadecimal-constant:
1531 hexadecimal-prefix hexadecimal-digit
1532 hexadecimal-constant hexadecimal-digit
1533
1534 hexadecimal-prefix:
1535 0x
1536 0X
1537
1538 nonzero-digit:
1539 [1-9]
1540
1541 integer-suffix:
1542 unsigned-suffix long-suffix-opt
1543 unsigned-suffix long-long-suffix
1544 long-suffix unsigned-suffix-opt
1545 long-long-suffix unsigned-suffix-opt
1546
1547 unsigned-suffix:
1548 u
1549 U
1550
1551 long-suffix:
1552 l
1553 L
1554
1555 long-long-suffix:
1556 ll
1557 LL
1558
1559 enumeration-constant:
1560 identifier
1561 string-literal
1562
1563 character-constant:
1564 ' c-char-sequence '
1565 L' c-char-sequence '
1566
1567 c-char-sequence:
1568 c-char
1569 c-char-sequence c-char
1570
1571 c-char:
1572 any member of source charset except single-quote ('), backslash
1573 (\), or new-line character.
1574 escape-sequence
1575
1576 escape-sequence:
1577 simple-escape-sequence
1578 octal-escape-sequence
1579 hexadecimal-escape-sequence
1580 universal-character-name
1581
1582 simple-escape-sequence: one of
1583 \' \" \? \\ \a \b \f \n \r \t \v
1584
1585 octal-escape-sequence:
1586 \ octal-digit
1587 \ octal-digit octal-digit
1588 \ octal-digit octal-digit octal-digit
1589
1590 hexadecimal-escape-sequence:
1591 \x hexadecimal-digit
1592 hexadecimal-escape-sequence hexadecimal-digit
1593
1594 1.6) String literals
1595
1596 string-literal:
1597 " s-char-sequence-opt "
1598 L" s-char-sequence-opt "
1599
1600 s-char-sequence:
1601 s-char
1602 s-char-sequence s-char
1603
1604 s-char:
1605 any member of source charset except double-quote ("), backslash
1606 (\), or new-line character.
1607 escape-sequence
1608
1609 1.7) Punctuators
1610
1611 punctuator: one of
1612 [ ] ( ) { } . -> * + - < > : ; ... = ,
1613
1614
1615 2) Phrase structure grammar
1616
1617 primary-expression:
1618 identifier
1619 constant
1620 string-literal
1621 ( unary-expression )
1622
1623 postfix-expression:
1624 primary-expression
1625 postfix-expression [ unary-expression ]
1626 postfix-expression . identifier
1627 postfix-expressoin -> identifier
1628
1629 unary-expression:
1630 postfix-expression
1631 unary-operator postfix-expression
1632
1633 unary-operator: one of
1634 + -
1635
1636 assignment-operator:
1637 =
1638
1639 type-assignment-operator:
1640 :=
1641
1642 constant-expression-range:
1643 unary-expression ... unary-expression
1644
1645 2.2) Declarations:
1646
1647 declaration:
1648 declaration-specifiers declarator-list-opt ;
1649 ctf-specifier ;
1650
1651 declaration-specifiers:
1652 storage-class-specifier declaration-specifiers-opt
1653 type-specifier declaration-specifiers-opt
1654 type-qualifier declaration-specifiers-opt
1655
1656 declarator-list:
1657 declarator
1658 declarator-list , declarator
1659
1660 abstract-declarator-list:
1661 abstract-declarator
1662 abstract-declarator-list , abstract-declarator
1663
1664 storage-class-specifier:
1665 typedef
1666
1667 type-specifier:
1668 void
1669 char
1670 short
1671 int
1672 long
1673 float
1674 double
1675 signed
1676 unsigned
1677 _Bool
1678 _Complex
1679 _Imaginary
1680 struct-specifier
1681 variant-specifier
1682 enum-specifier
1683 typedef-name
1684 ctf-type-specifier
1685
1686 align-attribute:
1687 align ( unary-expression )
1688
1689 struct-specifier:
1690 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1691 struct identifier align-attribute-opt
1692
1693 struct-or-variant-declaration-list:
1694 struct-or-variant-declaration
1695 struct-or-variant-declaration-list struct-or-variant-declaration
1696
1697 struct-or-variant-declaration:
1698 specifier-qualifier-list struct-or-variant-declarator-list ;
1699 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
1700 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1701 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
1702
1703 specifier-qualifier-list:
1704 type-specifier specifier-qualifier-list-opt
1705 type-qualifier specifier-qualifier-list-opt
1706
1707 struct-or-variant-declarator-list:
1708 struct-or-variant-declarator
1709 struct-or-variant-declarator-list , struct-or-variant-declarator
1710
1711 struct-or-variant-declarator:
1712 declarator
1713 declarator-opt : unary-expression
1714
1715 variant-specifier:
1716 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1717 variant identifier variant-tag
1718
1719 variant-tag:
1720 < unary-expression >
1721
1722 enum-specifier:
1723 enum identifier-opt { enumerator-list }
1724 enum identifier-opt { enumerator-list , }
1725 enum identifier
1726 enum identifier-opt : declaration-specifiers { enumerator-list }
1727 enum identifier-opt : declaration-specifiers { enumerator-list , }
1728
1729 enumerator-list:
1730 enumerator
1731 enumerator-list , enumerator
1732
1733 enumerator:
1734 enumeration-constant
1735 enumeration-constant assignment-operator unary-expression
1736 enumeration-constant assignment-operator constant-expression-range
1737
1738 type-qualifier:
1739 const
1740
1741 declarator:
1742 pointer-opt direct-declarator
1743
1744 direct-declarator:
1745 identifier
1746 ( declarator )
1747 direct-declarator [ unary-expression ]
1748
1749 abstract-declarator:
1750 pointer-opt direct-abstract-declarator
1751
1752 direct-abstract-declarator:
1753 identifier-opt
1754 ( abstract-declarator )
1755 direct-abstract-declarator [ unary-expression ]
1756 direct-abstract-declarator [ ]
1757
1758 pointer:
1759 * type-qualifier-list-opt
1760 * type-qualifier-list-opt pointer
1761
1762 type-qualifier-list:
1763 type-qualifier
1764 type-qualifier-list type-qualifier
1765
1766 typedef-name:
1767 identifier
1768
1769 2.3) CTF-specific declarations
1770
1771 ctf-specifier:
1772 clock { ctf-assignment-expression-list-opt }
1773 event { ctf-assignment-expression-list-opt }
1774 stream { ctf-assignment-expression-list-opt }
1775 env { ctf-assignment-expression-list-opt }
1776 trace { ctf-assignment-expression-list-opt }
1777 callsite { ctf-assignment-expression-list-opt }
1778 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1779 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
1780
1781 ctf-type-specifier:
1782 floating_point { ctf-assignment-expression-list-opt }
1783 integer { ctf-assignment-expression-list-opt }
1784 string { ctf-assignment-expression-list-opt }
1785 string
1786
1787 ctf-assignment-expression-list:
1788 ctf-assignment-expression ;
1789 ctf-assignment-expression-list ctf-assignment-expression ;
1790
1791 ctf-assignment-expression:
1792 unary-expression assignment-operator unary-expression
1793 unary-expression type-assignment-operator type-specifier
1794 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
1795 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1796 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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