00ffe4a81ae8dbf571e28bd5335766562be03979
[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 The timestamp at the beginning of an event packet is guaranteed to be
721 below or equal the timestamp at the end of that event packet.
722 The timestamp at the end of an event packet is guaranteed to be below
723 or equal the timestamps at the end of any following packet within the
724 same stream. See Section 8. Clocks for more detail.
725 - Events discarded count
726 - Snapshot of a per-stream free-running counter, counting the number of
727 events discarded that were supposed to be written in the stream after
728 the last event in the event packet.
729 * Note: producer-consumer buffer full condition can fill the current
730 event packet with padding so we know exactly where events have been
731 discarded. However, if the buffer full condition chooses not
732 to fill the current event packet with padding, all we know
733 about the timestamp range in which the events have been
734 discarded is that it is somewhere between the beginning and
735 the end of the packet.
736 - Lossless compression scheme used for the event packet content. Applied
737 directly to raw data. New types of compression can be added in following
738 versions of the format.
739 0: no compression scheme
740 1: bzip2
741 2: gzip
742 3: xz
743 - Cypher used for the event packet content. Applied after compression.
744 0: no encryption
745 1: AES
746 - Checksum scheme used for the event packet content. Applied after encryption.
747 0: no checksum
748 1: md5
749 2: sha1
750 3: crc32
751
752 5.1 Event Packet Header Description
753
754 The event packet header layout is indicated by the trace packet.header
755 field. Here is a recommended structure type for the packet header with
756 the fields typically expected (although these fields are each optional):
757
758 struct event_packet_header {
759 uint32_t magic;
760 uint8_t uuid[16];
761 uint32_t stream_id;
762 };
763
764 trace {
765 ...
766 packet.header := struct event_packet_header;
767 };
768
769 If the magic number is not present, tools such as "file" will have no
770 mean to discover the file type.
771
772 If the uuid is not present, no validation that the meta-data actually
773 corresponds to the stream is performed.
774
775 If the stream_id packet header field is missing, the trace can only
776 contain a single stream. Its "id" field can be left out, and its events
777 don't need to declare a "stream_id" field.
778
779
780 5.2 Event Packet Context Description
781
782 Event packet context example. These are declared within the stream declaration
783 in the meta-data. All these fields are optional. If the packet size field is
784 missing, the whole stream only contains a single packet. If the content
785 size field is missing, the packet is filled (no padding). The content
786 and packet sizes include all headers.
787
788 An example event packet context type:
789
790 struct event_packet_context {
791 uint64_t timestamp_begin;
792 uint64_t timestamp_end;
793 uint32_t checksum;
794 uint32_t stream_packet_count;
795 uint32_t events_discarded;
796 uint32_t cpu_id;
797 uint64_t/uint32_t/uint16_t content_size;
798 uint64_t/uint32_t/uint16_t packet_size;
799 uint8_t compression_scheme;
800 uint8_t encryption_scheme;
801 uint8_t checksum_scheme;
802 };
803
804
805 6. Event Structure
806
807 The overall structure of an event is:
808
809 1 - Event Header (as specified by the stream meta-data)
810 2 - Stream Event Context (as specified by the stream meta-data)
811 3 - Event Context (as specified by the event meta-data)
812 4 - Event Payload (as specified by the event meta-data)
813
814 This structure defines an implicit dynamic scoping, where variants
815 located in inner structures (those with a higher number in the listing
816 above) can refer to the fields of outer structures (with lower number in
817 the listing above). See Section 7.3 TSDL Scopes for more detail.
818
819 6.1 Event Header
820
821 Event headers can be described within the meta-data. We hereby propose, as an
822 example, two types of events headers. Type 1 accommodates streams with less than
823 31 event IDs. Type 2 accommodates streams with 31 or more event IDs.
824
825 One major factor can vary between streams: the number of event IDs assigned to
826 a stream. Luckily, this information tends to stay relatively constant (modulo
827 event registration while trace is being recorded), so we can specify different
828 representations for streams containing few event IDs and streams containing
829 many event IDs, so we end up representing the event ID and time-stamp as
830 densely as possible in each case.
831
832 The header is extended in the rare occasions where the information cannot be
833 represented in the ranges available in the standard event header. They are also
834 used in the rare occasions where the data required for a field could not be
835 collected: the flag corresponding to the missing field within the missing_fields
836 array is then set to 1.
837
838 Types uintX_t represent an X-bit unsigned integer, as declared with
839 either:
840
841 typealias integer { size = X; align = X; signed = false; } := uintX_t;
842
843 or
844
845 typealias integer { size = X; align = 1; signed = false; } := uintX_t;
846
847 For more information about timestamp fields, see Section 8. Clocks.
848
849 6.1.1 Type 1 - Few event IDs
850
851 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
852 preference).
853 - Native architecture byte ordering.
854 - For "compact" selection
855 - Fixed size: 32 bits.
856 - For "extended" selection
857 - Size depends on the architecture and variant alignment.
858
859 struct event_header_1 {
860 /*
861 * id: range: 0 - 30.
862 * id 31 is reserved to indicate an extended header.
863 */
864 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
865 variant <id> {
866 struct {
867 uint27_t timestamp;
868 } compact;
869 struct {
870 uint32_t id; /* 32-bit event IDs */
871 uint64_t timestamp; /* 64-bit timestamps */
872 } extended;
873 } v;
874 } align(32); /* or align(8) */
875
876
877 6.1.2 Type 2 - Many event IDs
878
879 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
880 preference).
881 - Native architecture byte ordering.
882 - For "compact" selection
883 - Size depends on the architecture and variant alignment.
884 - For "extended" selection
885 - Size depends on the architecture and variant alignment.
886
887 struct event_header_2 {
888 /*
889 * id: range: 0 - 65534.
890 * id 65535 is reserved to indicate an extended header.
891 */
892 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
893 variant <id> {
894 struct {
895 uint32_t timestamp;
896 } compact;
897 struct {
898 uint32_t id; /* 32-bit event IDs */
899 uint64_t timestamp; /* 64-bit timestamps */
900 } extended;
901 } v;
902 } align(16); /* or align(8) */
903
904
905 6.2 Stream Event Context and Event Context
906
907 The event context contains information relative to the current event.
908 The choice and meaning of this information is specified by the TSDL
909 stream and event meta-data descriptions. The stream context is applied
910 to all events within the stream. The stream context structure follows
911 the event header. The event context is applied to specific events. Its
912 structure follows the stream context structure.
913
914 An example of stream-level event context is to save the event payload size with
915 each event, or to save the current PID with each event. These are declared
916 within the stream declaration within the meta-data:
917
918 stream {
919 ...
920 event.context := struct {
921 uint pid;
922 uint16_t payload_size;
923 };
924 };
925
926 An example of event-specific event context is to declare a bitmap of missing
927 fields, only appended after the stream event context if the extended event
928 header is selected. NR_FIELDS is the number of fields within the event (a
929 numeric value).
930
931 event {
932 context = struct {
933 variant <id> {
934 struct { } compact;
935 struct {
936 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
937 } extended;
938 } v;
939 };
940 ...
941 }
942
943 6.3 Event Payload
944
945 An event payload contains fields specific to a given event type. The fields
946 belonging to an event type are described in the event-specific meta-data
947 within a structure type.
948
949 6.3.1 Padding
950
951 No padding at the end of the event payload. This differs from the ISO/C standard
952 for structures, but follows the CTF standard for structures. In a trace, even
953 though it makes sense to align the beginning of a structure, it really makes no
954 sense to add padding at the end of the structure, because structures are usually
955 not followed by a structure of the same type.
956
957 This trick can be done by adding a zero-length "end" field at the end of the C
958 structures, and by using the offset of this field rather than using sizeof()
959 when calculating the size of a structure (see Appendix "A. Helper macros").
960
961 6.3.2 Alignment
962
963 The event payload is aligned on the largest alignment required by types
964 contained within the payload. (This follows the ISO/C standard for structures)
965
966
967 7. Trace Stream Description Language (TSDL)
968
969 The Trace Stream Description Language (TSDL) allows expression of the
970 binary trace streams layout in a C99-like Domain Specific Language
971 (DSL).
972
973
974 7.1 Meta-data
975
976 The trace stream layout description is located in the trace meta-data.
977 The meta-data is itself located in a stream identified by its name:
978 "metadata".
979
980 The meta-data description can be expressed in two different formats:
981 text-only and packet-based. The text-only description facilitates
982 generation of meta-data and provides a convenient way to enter the
983 meta-data information by hand. The packet-based meta-data provides the
984 CTF stream packet facilities (checksumming, compression, encryption,
985 network-readiness) for meta-data stream generated and transported by a
986 tracer.
987
988 The text-only meta-data file is a plain-text TSDL description. This file
989 must begin with the following characters to identify the file as a CTF
990 TSDL text-based metadata file (without the double-quotes) :
991
992 "/* CTF"
993
994 It must be followed by a space, and the version of the specification
995 followed by the CTF trace, e.g.:
996
997 " 1.8"
998
999 These characters allow automated discovery of file type and CTF
1000 specification version. They are interpreted as a the beginning of a
1001 comment by the TSDL metadata parser. The comment can be continued to
1002 contain extra commented characters before it is closed.
1003
1004 The packet-based meta-data is made of "meta-data packets", which each
1005 start with a meta-data packet header. The packet-based meta-data
1006 description is detected by reading the magic number "0x75D11D57" at the
1007 beginning of the file. This magic number is also used to detect the
1008 endianness of the architecture by trying to read the CTF magic number
1009 and its counterpart in reversed endianness. The events within the
1010 meta-data stream have no event header nor event context. Each event only
1011 contains a special "sequence" payload, which is a sequence of bits which
1012 length is implicitly calculated by using the
1013 "trace.packet.header.content_size" field, minus the packet header size.
1014 The formatting of this sequence of bits is a plain-text representation
1015 of the TSDL description. Each meta-data packet start with a special
1016 packet header, specific to the meta-data stream, which contains,
1017 exactly:
1018
1019 struct metadata_packet_header {
1020 uint32_t magic; /* 0x75D11D57 */
1021 uint8_t uuid[16]; /* Unique Universal Identifier */
1022 uint32_t checksum; /* 0 if unused */
1023 uint32_t content_size; /* in bits */
1024 uint32_t packet_size; /* in bits */
1025 uint8_t compression_scheme; /* 0 if unused */
1026 uint8_t encryption_scheme; /* 0 if unused */
1027 uint8_t checksum_scheme; /* 0 if unused */
1028 uint8_t major; /* CTF spec version major number */
1029 uint8_t minor; /* CTF spec version minor number */
1030 };
1031
1032 The packet-based meta-data can be converted to a text-only meta-data by
1033 concatenating all the strings it contains.
1034
1035 In the textual representation of the meta-data, the text contained
1036 within "/*" and "*/", as well as within "//" and end of line, are
1037 treated as comments. Boolean values can be represented as true, TRUE,
1038 or 1 for true, and false, FALSE, or 0 for false. Within the string-based
1039 meta-data description, the trace UUID is represented as a string of
1040 hexadecimal digits and dashes "-". In the event packet header, the trace
1041 UUID is represented as an array of bytes.
1042
1043
1044 7.2 Declaration vs Definition
1045
1046 A declaration associates a layout to a type, without specifying where
1047 this type is located in the event structure hierarchy (see Section 6).
1048 This therefore includes typedef, typealias, as well as all type
1049 specifiers. In certain circumstances (typedef, structure field and
1050 variant field), a declaration is followed by a declarator, which specify
1051 the newly defined type name (for typedef), or the field name (for
1052 declarations located within structure and variants). Array and sequence,
1053 declared with square brackets ("[" "]"), are part of the declarator,
1054 similarly to C99. The enumeration base type is specified by
1055 ": enum_base", which is part of the type specifier. The variant tag
1056 name, specified between "<" ">", is also part of the type specifier.
1057
1058 A definition associates a type to a location in the event structure
1059 hierarchy (see Section 6). This association is denoted by ":=", as shown
1060 in Section 7.3.
1061
1062
1063 7.3 TSDL Scopes
1064
1065 TSDL uses three different types of scoping: a lexical scope is used for
1066 declarations and type definitions, and static and dynamic scopes are
1067 used for variants references to tag fields (with relative and absolute
1068 path lookups) and for sequence references to length fields.
1069
1070 7.3.1 Lexical Scope
1071
1072 Each of "trace", "env", "stream", "event", "struct" and "variant" have
1073 their own nestable declaration scope, within which types can be declared
1074 using "typedef" and "typealias". A root declaration scope also contains
1075 all declarations located outside of any of the aforementioned
1076 declarations. An inner declaration scope can refer to type declared
1077 within its container lexical scope prior to the inner declaration scope.
1078 Redefinition of a typedef or typealias is not valid, although hiding an
1079 upper scope typedef or typealias is allowed within a sub-scope.
1080
1081 7.3.2 Static and Dynamic Scopes
1082
1083 A local static scope consists in the scope generated by the declaration
1084 of fields within a compound type. A static scope is a local static scope
1085 augmented with the nested sub-static-scopes it contains.
1086
1087 A dynamic scope consists in the static scope augmented with the
1088 implicit event structure definition hierarchy presented at Section 6.
1089
1090 Multiple declarations of the same field name within a local static scope
1091 is not valid. It is however valid to re-use the same field name in
1092 different local scopes.
1093
1094 Nested static and dynamic scopes form lookup paths. These are used for
1095 variant tag and sequence length references. They are used at the variant
1096 and sequence definition site to look up the location of the tag field
1097 associated with a variant, and to lookup up the location of the length
1098 field associated with a sequence.
1099
1100 Variants and sequences can refer to a tag field either using a relative
1101 path or an absolute path. The relative path is relative to the scope in
1102 which the variant or sequence performing the lookup is located.
1103 Relative paths are only allowed to lookup within the same static scope,
1104 which includes its nested static scopes. Lookups targeting parent static
1105 scopes need to be performed with an absolute path.
1106
1107 Absolute path lookups use the full path including the dynamic scope
1108 followed by a "." and then the static scope. Therefore, variants (or
1109 sequences) in lower levels in the dynamic scope (e.g. event context) can
1110 refer to a tag (or length) field located in upper levels (e.g. in the
1111 event header) by specifying, in this case, the associated tag with
1112 <stream.event.header.field_name>. This allows, for instance, the event
1113 context to define a variant referring to the "id" field of the event
1114 header as selector.
1115
1116 The dynamic scope prefixes are thus:
1117
1118 - Trace Environment: <env. >,
1119 - Trace Packet Header: <trace.packet.header. >,
1120 - Stream Packet Context: <stream.packet.context. >,
1121 - Event Header: <stream.event.header. >,
1122 - Stream Event Context: <stream.event.context. >,
1123 - Event Context: <event.context. >,
1124 - Event Payload: <event.fields. >.
1125
1126
1127 The target dynamic scope must be specified explicitly when referring to
1128 a field outside of the static scope (absolute scope reference). No
1129 conflict can occur between relative and dynamic paths, because the
1130 keywords "trace", "stream", and "event" are reserved, and thus
1131 not permitted as field names. It is recommended that field names
1132 clashing with CTF and C99 reserved keywords use an underscore prefix to
1133 eliminate the risk of generating a description containing an invalid
1134 field name. Consequently, fields starting with an underscore should have
1135 their leading underscore removed by the CTF trace readers.
1136
1137
1138 The information available in the dynamic scopes can be thought of as the
1139 current tracing context. At trace production, information about the
1140 current context is saved into the specified scope field levels. At trace
1141 consumption, for each event, the current trace context is therefore
1142 readable by accessing the upper dynamic scopes.
1143
1144
1145 7.4 TSDL Examples
1146
1147 The grammar representing the TSDL meta-data is presented in Appendix C.
1148 TSDL Grammar. This section presents a rather lighter reading that
1149 consists in examples of TSDL meta-data, with template values.
1150
1151 The stream "id" can be left out if there is only one stream in the
1152 trace. The event "id" field can be left out if there is only one event
1153 in a stream.
1154
1155 trace {
1156 major = value; /* CTF spec version major number */
1157 minor = value; /* CTF spec version minor number */
1158 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
1159 byte_order = be OR le; /* Endianness (required) */
1160 packet.header := struct {
1161 uint32_t magic;
1162 uint8_t uuid[16];
1163 uint32_t stream_id;
1164 };
1165 };
1166
1167 /*
1168 * The "env" (environment) scope contains assignment expressions. The
1169 * field names and content are implementation-defined.
1170 */
1171 env {
1172 pid = value; /* example */
1173 proc_name = "name"; /* example */
1174 ...
1175 };
1176
1177 stream {
1178 id = stream_id;
1179 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
1180 event.header := event_header_1 OR event_header_2;
1181 event.context := struct {
1182 ...
1183 };
1184 packet.context := struct {
1185 ...
1186 };
1187 };
1188
1189 event {
1190 name = "event_name";
1191 id = value; /* Numeric identifier within the stream */
1192 stream_id = stream_id;
1193 loglevel = value;
1194 model.emf.uri = "string";
1195 context := struct {
1196 ...
1197 };
1198 fields := struct {
1199 ...
1200 };
1201 };
1202
1203 callsite {
1204 name = "event_name";
1205 func = "func_name";
1206 file = "myfile.c";
1207 line = 39;
1208 ip = 0x40096c;
1209 };
1210
1211 /* More detail on types in section 4. Types */
1212
1213 /*
1214 * Named types:
1215 *
1216 * Type declarations behave similarly to the C standard.
1217 */
1218
1219 typedef aliased_type_specifiers new_type_declarators;
1220
1221 /* e.g.: typedef struct example new_type_name[10]; */
1222
1223 /*
1224 * typealias
1225 *
1226 * The "typealias" declaration can be used to give a name (including
1227 * pointer declarator specifier) to a type. It should also be used to
1228 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1229 * Typealias is a superset of "typedef": it also allows assignment of a
1230 * simple variable identifier to a type.
1231 */
1232
1233 typealias type_class {
1234 ...
1235 } := type_specifiers type_declarator;
1236
1237 /*
1238 * e.g.:
1239 * typealias integer {
1240 * size = 32;
1241 * align = 32;
1242 * signed = false;
1243 * } := struct page *;
1244 *
1245 * typealias integer {
1246 * size = 32;
1247 * align = 32;
1248 * signed = true;
1249 * } := int;
1250 */
1251
1252 struct name {
1253 ...
1254 };
1255
1256 variant name {
1257 ...
1258 };
1259
1260 enum name : integer_type {
1261 ...
1262 };
1263
1264
1265 /*
1266 * Unnamed types, contained within compound type fields, typedef or typealias.
1267 */
1268
1269 struct {
1270 ...
1271 }
1272
1273 struct {
1274 ...
1275 } align(value)
1276
1277 variant {
1278 ...
1279 }
1280
1281 enum : integer_type {
1282 ...
1283 }
1284
1285 typedef type new_type[length];
1286
1287 struct {
1288 type field_name[length];
1289 }
1290
1291 typedef type new_type[length_type];
1292
1293 struct {
1294 type field_name[length_type];
1295 }
1296
1297 integer {
1298 ...
1299 }
1300
1301 floating_point {
1302 ...
1303 }
1304
1305 struct {
1306 integer_type field_name:size; /* GNU/C bitfield */
1307 }
1308
1309 struct {
1310 string field_name;
1311 }
1312
1313
1314 8. Clocks
1315
1316 Clock metadata allows to describe the clock topology of the system, as
1317 well as to detail each clock parameter. In absence of clock description,
1318 it is assumed that all fields named "timestamp" use the same clock
1319 source, which increments once per nanosecond.
1320
1321 Describing a clock and how it is used by streams is threefold: first,
1322 the clock and clock topology should be described in a "clock"
1323 description block, e.g.:
1324
1325 clock {
1326 name = cycle_counter_sync;
1327 uuid = "62189bee-96dc-11e0-91a8-cfa3d89f3923";
1328 description = "Cycle counter synchronized across CPUs";
1329 freq = 1000000000; /* frequency, in Hz */
1330 /* precision in seconds is: 1000 * (1/freq) */
1331 precision = 1000;
1332 /*
1333 * clock value offset from Epoch is:
1334 * offset_s + (offset * (1/freq))
1335 */
1336 offset_s = 1326476837;
1337 offset = 897235420;
1338 absolute = FALSE;
1339 };
1340
1341 The mandatory "name" field specifies the name of the clock identifier,
1342 which can later be used as a reference. The optional field "uuid" is the
1343 unique identifier of the clock. It can be used to correlate different
1344 traces that use the same clock. An optional textual description string
1345 can be added with the "description" field. The "freq" field is the
1346 initial frequency of the clock, in Hz. If the "freq" field is not
1347 present, the frequency is assumed to be 1000000000 (providing clock
1348 increment of 1 ns). The optional "precision" field details the
1349 uncertainty on the clock measurements, in (1/freq) units. The "offset_s"
1350 and "offset" fields indicate the offset from POSIX.1 Epoch, 1970-01-01
1351 00:00:00 +0000 (UTC), to the zero of value of the clock. The "offset_s"
1352 field is in seconds. The "offset" field is in (1/freq) units. If any of
1353 the "offset_s" or "offset" field is not present, it is assigned the 0
1354 value. The field "absolute" is TRUE if the clock is a global reference
1355 across different clock uuid (e.g. NTP time). Otherwise, "absolute" is
1356 FALSE, and the clock can be considered as synchronized only with other
1357 clocks that have the same uuid.
1358
1359
1360 Secondly, a reference to this clock should be added within an integer
1361 type:
1362
1363 typealias integer {
1364 size = 64; align = 1; signed = false;
1365 map = clock.cycle_counter_sync.value;
1366 } := uint64_ccnt_t;
1367
1368 Thirdly, stream declarations can reference the clock they use as a
1369 time-stamp source:
1370
1371 struct packet_context {
1372 uint64_ccnt_t ccnt_begin;
1373 uint64_ccnt_t ccnt_end;
1374 /* ... */
1375 };
1376
1377 stream {
1378 /* ... */
1379 event.header := struct {
1380 uint64_ccnt_t timestamp;
1381 /* ... */
1382 }
1383 packet.context := struct packet_context;
1384 };
1385
1386 For a N-bit integer type referring to a clock, if the integer overflows
1387 compared to the N low order bits of the clock prior value found in the
1388 same stream, then it is assumed that one, and only one, overflow
1389 occurred. It is therefore important that events encoding time on a small
1390 number of bits happen frequently enough to detect when more than one
1391 N-bit overflow occurs.
1392
1393 In a packet context, clock field names ending with "_begin" and "_end"
1394 have a special meaning: this refers to the time-stamps at, respectively,
1395 the beginning and the end of each packet.
1396
1397
1398 A. Helper macros
1399
1400 The two following macros keep track of the size of a GNU/C structure without
1401 padding at the end by placing HEADER_END as the last field. A one byte end field
1402 is used for C90 compatibility (C99 flexible arrays could be used here). Note
1403 that this does not affect the effective structure size, which should always be
1404 calculated with the header_sizeof() helper.
1405
1406 #define HEADER_END char end_field
1407 #define header_sizeof(type) offsetof(typeof(type), end_field)
1408
1409
1410 B. Stream Header Rationale
1411
1412 An event stream is divided in contiguous event packets of variable size. These
1413 subdivisions allow the trace analyzer to perform a fast binary search by time
1414 within the stream (typically requiring to index only the event packet headers)
1415 without reading the whole stream. These subdivisions have a variable size to
1416 eliminate the need to transfer the event packet padding when partially filled
1417 event packets must be sent when streaming a trace for live viewing/analysis.
1418 An event packet can contain a certain amount of padding at the end. Dividing
1419 streams into event packets is also useful for network streaming over UDP and
1420 flight recorder mode tracing (a whole event packet can be swapped out of the
1421 buffer atomically for reading).
1422
1423 The stream header is repeated at the beginning of each event packet to allow
1424 flexibility in terms of:
1425
1426 - streaming support,
1427 - allowing arbitrary buffers to be discarded without making the trace
1428 unreadable,
1429 - allow UDP packet loss handling by either dealing with missing event packet
1430 or asking for re-transmission.
1431 - transparently support flight recorder mode,
1432 - transparently support crash dump.
1433
1434
1435 C. TSDL Grammar
1436
1437 /*
1438 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
1439 *
1440 * Inspired from the C99 grammar:
1441 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
1442 * and c++1x grammar (draft)
1443 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
1444 *
1445 * Specialized for CTF needs by including only constant and declarations from
1446 * C99 (excluding function declarations), and by adding support for variants,
1447 * sequences and CTF-specific specifiers. Enumeration container types
1448 * semantic is inspired from c++1x enum-base.
1449 */
1450
1451 1) Lexical grammar
1452
1453 1.1) Lexical elements
1454
1455 token:
1456 keyword
1457 identifier
1458 constant
1459 string-literal
1460 punctuator
1461
1462 1.2) Keywords
1463
1464 keyword: is one of
1465
1466 align
1467 callsite
1468 const
1469 char
1470 clock
1471 double
1472 enum
1473 env
1474 event
1475 floating_point
1476 float
1477 integer
1478 int
1479 long
1480 short
1481 signed
1482 stream
1483 string
1484 struct
1485 trace
1486 typealias
1487 typedef
1488 unsigned
1489 variant
1490 void
1491 _Bool
1492 _Complex
1493 _Imaginary
1494
1495
1496 1.3) Identifiers
1497
1498 identifier:
1499 identifier-nondigit
1500 identifier identifier-nondigit
1501 identifier digit
1502
1503 identifier-nondigit:
1504 nondigit
1505 universal-character-name
1506 any other implementation-defined characters
1507
1508 nondigit:
1509 _
1510 [a-zA-Z] /* regular expression */
1511
1512 digit:
1513 [0-9] /* regular expression */
1514
1515 1.4) Universal character names
1516
1517 universal-character-name:
1518 \u hex-quad
1519 \U hex-quad hex-quad
1520
1521 hex-quad:
1522 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1523
1524 1.5) Constants
1525
1526 constant:
1527 integer-constant
1528 enumeration-constant
1529 character-constant
1530
1531 integer-constant:
1532 decimal-constant integer-suffix-opt
1533 octal-constant integer-suffix-opt
1534 hexadecimal-constant integer-suffix-opt
1535
1536 decimal-constant:
1537 nonzero-digit
1538 decimal-constant digit
1539
1540 octal-constant:
1541 0
1542 octal-constant octal-digit
1543
1544 hexadecimal-constant:
1545 hexadecimal-prefix hexadecimal-digit
1546 hexadecimal-constant hexadecimal-digit
1547
1548 hexadecimal-prefix:
1549 0x
1550 0X
1551
1552 nonzero-digit:
1553 [1-9]
1554
1555 integer-suffix:
1556 unsigned-suffix long-suffix-opt
1557 unsigned-suffix long-long-suffix
1558 long-suffix unsigned-suffix-opt
1559 long-long-suffix unsigned-suffix-opt
1560
1561 unsigned-suffix:
1562 u
1563 U
1564
1565 long-suffix:
1566 l
1567 L
1568
1569 long-long-suffix:
1570 ll
1571 LL
1572
1573 enumeration-constant:
1574 identifier
1575 string-literal
1576
1577 character-constant:
1578 ' c-char-sequence '
1579 L' c-char-sequence '
1580
1581 c-char-sequence:
1582 c-char
1583 c-char-sequence c-char
1584
1585 c-char:
1586 any member of source charset except single-quote ('), backslash
1587 (\), or new-line character.
1588 escape-sequence
1589
1590 escape-sequence:
1591 simple-escape-sequence
1592 octal-escape-sequence
1593 hexadecimal-escape-sequence
1594 universal-character-name
1595
1596 simple-escape-sequence: one of
1597 \' \" \? \\ \a \b \f \n \r \t \v
1598
1599 octal-escape-sequence:
1600 \ octal-digit
1601 \ octal-digit octal-digit
1602 \ octal-digit octal-digit octal-digit
1603
1604 hexadecimal-escape-sequence:
1605 \x hexadecimal-digit
1606 hexadecimal-escape-sequence hexadecimal-digit
1607
1608 1.6) String literals
1609
1610 string-literal:
1611 " s-char-sequence-opt "
1612 L" s-char-sequence-opt "
1613
1614 s-char-sequence:
1615 s-char
1616 s-char-sequence s-char
1617
1618 s-char:
1619 any member of source charset except double-quote ("), backslash
1620 (\), or new-line character.
1621 escape-sequence
1622
1623 1.7) Punctuators
1624
1625 punctuator: one of
1626 [ ] ( ) { } . -> * + - < > : ; ... = ,
1627
1628
1629 2) Phrase structure grammar
1630
1631 primary-expression:
1632 identifier
1633 constant
1634 string-literal
1635 ( unary-expression )
1636
1637 postfix-expression:
1638 primary-expression
1639 postfix-expression [ unary-expression ]
1640 postfix-expression . identifier
1641 postfix-expressoin -> identifier
1642
1643 unary-expression:
1644 postfix-expression
1645 unary-operator postfix-expression
1646
1647 unary-operator: one of
1648 + -
1649
1650 assignment-operator:
1651 =
1652
1653 type-assignment-operator:
1654 :=
1655
1656 constant-expression-range:
1657 unary-expression ... unary-expression
1658
1659 2.2) Declarations:
1660
1661 declaration:
1662 declaration-specifiers declarator-list-opt ;
1663 ctf-specifier ;
1664
1665 declaration-specifiers:
1666 storage-class-specifier declaration-specifiers-opt
1667 type-specifier declaration-specifiers-opt
1668 type-qualifier declaration-specifiers-opt
1669
1670 declarator-list:
1671 declarator
1672 declarator-list , declarator
1673
1674 abstract-declarator-list:
1675 abstract-declarator
1676 abstract-declarator-list , abstract-declarator
1677
1678 storage-class-specifier:
1679 typedef
1680
1681 type-specifier:
1682 void
1683 char
1684 short
1685 int
1686 long
1687 float
1688 double
1689 signed
1690 unsigned
1691 _Bool
1692 _Complex
1693 _Imaginary
1694 struct-specifier
1695 variant-specifier
1696 enum-specifier
1697 typedef-name
1698 ctf-type-specifier
1699
1700 align-attribute:
1701 align ( unary-expression )
1702
1703 struct-specifier:
1704 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1705 struct identifier align-attribute-opt
1706
1707 struct-or-variant-declaration-list:
1708 struct-or-variant-declaration
1709 struct-or-variant-declaration-list struct-or-variant-declaration
1710
1711 struct-or-variant-declaration:
1712 specifier-qualifier-list struct-or-variant-declarator-list ;
1713 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
1714 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1715 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
1716
1717 specifier-qualifier-list:
1718 type-specifier specifier-qualifier-list-opt
1719 type-qualifier specifier-qualifier-list-opt
1720
1721 struct-or-variant-declarator-list:
1722 struct-or-variant-declarator
1723 struct-or-variant-declarator-list , struct-or-variant-declarator
1724
1725 struct-or-variant-declarator:
1726 declarator
1727 declarator-opt : unary-expression
1728
1729 variant-specifier:
1730 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1731 variant identifier variant-tag
1732
1733 variant-tag:
1734 < unary-expression >
1735
1736 enum-specifier:
1737 enum identifier-opt { enumerator-list }
1738 enum identifier-opt { enumerator-list , }
1739 enum identifier
1740 enum identifier-opt : declaration-specifiers { enumerator-list }
1741 enum identifier-opt : declaration-specifiers { enumerator-list , }
1742
1743 enumerator-list:
1744 enumerator
1745 enumerator-list , enumerator
1746
1747 enumerator:
1748 enumeration-constant
1749 enumeration-constant assignment-operator unary-expression
1750 enumeration-constant assignment-operator constant-expression-range
1751
1752 type-qualifier:
1753 const
1754
1755 declarator:
1756 pointer-opt direct-declarator
1757
1758 direct-declarator:
1759 identifier
1760 ( declarator )
1761 direct-declarator [ unary-expression ]
1762
1763 abstract-declarator:
1764 pointer-opt direct-abstract-declarator
1765
1766 direct-abstract-declarator:
1767 identifier-opt
1768 ( abstract-declarator )
1769 direct-abstract-declarator [ unary-expression ]
1770 direct-abstract-declarator [ ]
1771
1772 pointer:
1773 * type-qualifier-list-opt
1774 * type-qualifier-list-opt pointer
1775
1776 type-qualifier-list:
1777 type-qualifier
1778 type-qualifier-list type-qualifier
1779
1780 typedef-name:
1781 identifier
1782
1783 2.3) CTF-specific declarations
1784
1785 ctf-specifier:
1786 clock { ctf-assignment-expression-list-opt }
1787 event { ctf-assignment-expression-list-opt }
1788 stream { ctf-assignment-expression-list-opt }
1789 env { ctf-assignment-expression-list-opt }
1790 trace { ctf-assignment-expression-list-opt }
1791 callsite { ctf-assignment-expression-list-opt }
1792 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1793 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
1794
1795 ctf-type-specifier:
1796 floating_point { ctf-assignment-expression-list-opt }
1797 integer { ctf-assignment-expression-list-opt }
1798 string { ctf-assignment-expression-list-opt }
1799 string
1800
1801 ctf-assignment-expression-list:
1802 ctf-assignment-expression ;
1803 ctf-assignment-expression-list ctf-assignment-expression ;
1804
1805 ctf-assignment-expression:
1806 unary-expression assignment-operator unary-expression
1807 unary-expression type-assignment-operator type-specifier
1808 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
1809 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1810 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
This page took 0.108213 seconds and 3 git commands to generate.