enum: Clarify behavior for omitted values after range
[ctf.git] / common-trace-format-specification.txt
1 Common Trace Format (CTF) Specification (v1.8.1)
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. These subdivisions have a variable size. An event packet can
122 contain a certain amount of padding at the end. The stream header is
123 repeated at the beginning of each event packet. The rationale for the
124 event stream design choices is explained in Appendix B. Stream Header
125 Rationale.
126
127 The event stream header will therefore be referred to as the "event packet
128 header" throughout the rest of this document.
129
130
131 4. Types
132
133 Types are organized as type classes. Each type class belong to either of two
134 kind of types: basic types or compound types.
135
136 4.1 Basic types
137
138 A basic type is a scalar type, as described in this section. It includes
139 integers, GNU/C bitfields, enumerations, and floating point values.
140
141 4.1.1 Type inheritance
142
143 Type specifications can be inherited to allow deriving types from a
144 type class. For example, see the uint32_t named type derived from the "integer"
145 type class below ("Integers" section). Types have a precise binary
146 representation in the trace. A type class has methods to read and write these
147 types, but must be derived into a type to be usable in an event field.
148
149 4.1.2 Alignment
150
151 We define "byte-packed" types as aligned on the byte size, namely 8-bit.
152 We define "bit-packed" types as following on the next bit, as defined by the
153 "Integers" section.
154
155 Each basic type must specify its alignment, in bits. Examples of
156 possible alignments are: bit-packed (align = 1), byte-packed (align =
157 8), or word-aligned (e.g. align = 32 or align = 64). The choice depends
158 on the architecture preference and compactness vs performance trade-offs
159 of the implementation. Architectures providing fast unaligned write
160 byte-packed basic types to save space, aligning each type on byte
161 boundaries (8-bit). Architectures with slow unaligned writes align types
162 on specific alignment values. If no specific alignment is declared for a
163 type, it is assumed to be bit-packed for integers with size not multiple
164 of 8 bits and for gcc bitfields. All other basic types are byte-packed
165 by default. It is however recommended to always specify the alignment
166 explicitly. Alignment values must be power of two. Compound types are
167 aligned as specified in their individual specification.
168
169 TSDL meta-data attribute representation of a specific alignment:
170
171 align = value; /* value in bits */
172
173 4.1.3 Byte order
174
175 By default, the native endianness of the source architecture the trace is used.
176 Byte order can be overridden for a basic type by specifying a "byte_order"
177 attribute. Typical use-case is to specify the network byte order (big endian:
178 "be") to save data captured from the network into the trace without conversion.
179 If not specified, the byte order is native.
180
181 TSDL meta-data representation:
182
183 byte_order = native OR network OR be OR le; /* network and be are aliases */
184
185 4.1.4 Size
186
187 Type size, in bits, for integers and floats is that returned by "sizeof()" in C
188 multiplied by CHAR_BIT.
189 We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
190 to 8 bits for cross-endianness compatibility.
191
192 TSDL meta-data representation:
193
194 size = value; (value is in bits)
195
196 4.1.5 Integers
197
198 Signed integers are represented in two-complement. Integer alignment,
199 size, signedness and byte ordering are defined in the TSDL meta-data.
200 Integers aligned on byte size (8-bit) and with length multiple of byte
201 size (8-bit) correspond to the C99 standard integers. In addition,
202 integers with alignment and/or size that are _not_ a multiple of the
203 byte size are permitted; these correspond to the C99 standard bitfields,
204 with the added specification that the CTF integer bitfields have a fixed
205 binary representation. A MIT-licensed reference implementation of the
206 CTF portable bitfields is available at:
207
208 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
209
210 Binary representation of integers:
211
212 - On little and big endian:
213 - Within a byte, high bits correspond to an integer high bits, and low bits
214 correspond to low bits.
215 - On little endian:
216 - Integer across multiple bytes are placed from the less significant to the
217 most significant.
218 - Consecutive integers are placed from lower bits to higher bits (even within
219 a byte).
220 - On big endian:
221 - Integer across multiple bytes are placed from the most significant to the
222 less significant.
223 - Consecutive integers are placed from higher bits to lower bits (even within
224 a byte).
225
226 This binary representation is derived from the bitfield implementation in GCC
227 for little and big endian. However, contrary to what GCC does, integers can
228 cross units boundaries (no padding is required). Padding can be explicitly
229 added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
230
231 TSDL meta-data representation:
232
233 integer {
234 signed = true OR false; /* default false */
235 byte_order = native OR network OR be OR le; /* default native */
236 size = value; /* value in bits, no default */
237 align = value; /* value in bits */
238 /* based used for pretty-printing output, default: decimal. */
239 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
240 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
241 /* character encoding, default: none */
242 encoding = none or UTF8 or ASCII;
243 }
244
245 Example of type inheritance (creation of a uint32_t named type):
246
247 typealias integer {
248 size = 32;
249 signed = false;
250 align = 32;
251 } := uint32_t;
252
253 Definition of a named 5-bit signed bitfield:
254
255 typealias integer {
256 size = 5;
257 signed = true;
258 align = 1;
259 } := int5_t;
260
261 The character encoding field can be used to specify that the integer
262 must be printed as a text character when read. e.g.:
263
264 typealias integer {
265 size = 8;
266 align = 8;
267 signed = false;
268 encoding = UTF8;
269 } := utf_char;
270
271
272 4.1.6 GNU/C bitfields
273
274 The GNU/C bitfields follow closely the integer representation, with a
275 particularity on alignment: if a bitfield cannot fit in the current unit, the
276 unit is padded and the bitfield starts at the following unit. The unit size is
277 defined by the size of the type "unit_type".
278
279 TSDL meta-data representation:
280
281 unit_type name:size;
282
283 As an example, the following structure declared in C compiled by GCC:
284
285 struct example {
286 short a:12;
287 short b:5;
288 };
289
290 The example structure is aligned on the largest element (short). The second
291 bitfield would be aligned on the next unit boundary, because it would not fit in
292 the current unit.
293
294 4.1.7 Floating point
295
296 The floating point values byte ordering is defined in the TSDL meta-data.
297
298 Floating point values follow the IEEE 754-2008 standard interchange formats.
299 Description of the floating point values include the exponent and mantissa size
300 in bits. Some requirements are imposed on the floating point values:
301
302 - FLT_RADIX must be 2.
303 - mant_dig is the number of digits represented in the mantissa. It is specified
304 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
305 LDBL_MANT_DIG as defined by <float.h>.
306 - exp_dig is the number of digits represented in the exponent. Given that
307 mant_dig is one bit more than its actual size in bits (leading 1 is not
308 needed) and also given that the sign bit always takes one bit, exp_dig can be
309 specified as:
310
311 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
312 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
313 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
314
315 TSDL meta-data representation:
316
317 floating_point {
318 exp_dig = value;
319 mant_dig = value;
320 byte_order = native OR network OR be OR le;
321 align = value;
322 }
323
324 Example of type inheritance:
325
326 typealias floating_point {
327 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
328 mant_dig = 24; /* FLT_MANT_DIG */
329 byte_order = native;
330 align = 32;
331 } := float;
332
333 TODO: define NaN, +inf, -inf behavior.
334
335 Bit-packed, byte-packed or larger alignments can be used for floating
336 point values, similarly to integers.
337
338 4.1.8 Enumerations
339
340 Enumerations are a mapping between an integer type and a table of strings. The
341 numerical representation of the enumeration follows the integer type specified
342 by the meta-data. The enumeration mapping table is detailed in the enumeration
343 description within the meta-data. The mapping table maps inclusive value
344 ranges (or single values) to strings. Instead of being limited to simple
345 "value -> string" mappings, these enumerations map
346 "[ start_value ... end_value ] -> string", which map inclusive ranges of
347 values to strings. An enumeration from the C language can be represented in
348 this format by having the same start_value and end_value for each element, which
349 is in fact a range of size 1. This single-value range is supported without
350 repeating the start and end values with the value = string declaration.
351
352 enum name : integer_type {
353 somestring = start_value1 ... end_value1,
354 "other string" = start_value2 ... end_value2,
355 yet_another_string, /* will be assigned to end_value2 + 1 */
356 "some other string" = value,
357 ...
358 };
359
360 If the values are omitted, the enumeration starts at 0 and increment of 1 for
361 each entry. An entry with omitted value that follows a range entry takes
362 as value the end_value of the previous range + 1:
363
364 enum name : unsigned int {
365 ZERO,
366 ONE,
367 TWO,
368 TEN = 10,
369 ELEVEN,
370 };
371
372 Overlapping ranges within a single enumeration are implementation defined.
373
374 A nameless enumeration can be declared as a field type or as part of a typedef:
375
376 enum : integer_type {
377 ...
378 }
379
380 Enumerations omitting the container type ": integer_type" use the "int"
381 type (for compatibility with C99). The "int" type must be previously
382 declared. E.g.:
383
384 typealias integer { size = 32; align = 32; signed = true } := int;
385
386 enum {
387 ...
388 }
389
390
391 4.2 Compound types
392
393 Compound are aggregation of type declarations. Compound types include
394 structures, variant, arrays, sequences, and strings.
395
396 4.2.1 Structures
397
398 Structures are aligned on the largest alignment required by basic types
399 contained within the structure. (This follows the ISO/C standard for structures)
400
401 TSDL meta-data representation of a named structure:
402
403 struct name {
404 field_type field_name;
405 field_type field_name;
406 ...
407 };
408
409 Example:
410
411 struct example {
412 integer { /* Nameless type */
413 size = 16;
414 signed = true;
415 align = 16;
416 } first_field_name;
417 uint64_t second_field_name; /* Named type declared in the meta-data */
418 };
419
420 The fields are placed in a sequence next to each other. They each
421 possess a field name, which is a unique identifier within the structure.
422 The identifier is not allowed to use any reserved keyword
423 (see Section C.1.2). Replacing reserved keywords with
424 underscore-prefixed field names is recommended. Fields starting with an
425 underscore should have their leading underscore removed by the CTF trace
426 readers.
427
428 A nameless structure can be declared as a field type or as part of a typedef:
429
430 struct {
431 ...
432 }
433
434 Alignment for a structure compound type can be forced to a minimum value
435 by adding an "align" specifier after the declaration of a structure
436 body. This attribute is read as: align(value). The value is specified in
437 bits. The structure will be aligned on the maximum value between this
438 attribute and the alignment required by the basic types contained within
439 the structure. e.g.
440
441 struct {
442 ...
443 } align(32)
444
445 4.2.2 Variants (Discriminated/Tagged Unions)
446
447 A CTF variant is a selection between different types. A CTF variant must
448 always be defined within the scope of a structure or within fields
449 contained within a structure (defined recursively). A "tag" enumeration
450 field must appear in either the same static scope, prior to the variant
451 field (in field declaration order), in an upper static scope , or in an
452 upper dynamic scope (see Section 7.3.2). The type selection is indicated
453 by the mapping from the enumeration value to the string used as variant
454 type selector. The field to use as tag is specified by the "tag_field",
455 specified between "< >" after the "variant" keyword for unnamed
456 variants, and after "variant name" for named variants.
457
458 The alignment of the variant is the alignment of the type as selected by the tag
459 value for the specific instance of the variant. The alignment of the type
460 containing the variant is independent of the variant alignment. The size of the
461 variant is the size as selected by the tag value for the specific instance of
462 the variant.
463
464 Each variant type selector possess a field name, which is a unique
465 identifier within the variant. The identifier is not allowed to use any
466 reserved keyword (see Section C.1.2). Replacing reserved keywords with
467 underscore-prefixed field names is recommended. Fields starting with an
468 underscore should have their leading underscore removed by the CTF trace
469 readers.
470
471
472 A named variant declaration followed by its definition within a structure
473 declaration:
474
475 variant name {
476 field_type sel1;
477 field_type sel2;
478 field_type sel3;
479 ...
480 };
481
482 struct {
483 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
484 ...
485 variant name <tag_field> v;
486 }
487
488 An unnamed variant definition within a structure is expressed by the following
489 TSDL meta-data:
490
491 struct {
492 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
493 ...
494 variant <tag_field> {
495 field_type sel1;
496 field_type sel2;
497 field_type sel3;
498 ...
499 } v;
500 }
501
502 Example of a named variant within a sequence that refers to a single tag field:
503
504 variant example {
505 uint32_t a;
506 uint64_t b;
507 short c;
508 };
509
510 struct {
511 enum : uint2_t { a, b, c } choice;
512 unsigned int seqlen;
513 variant example <choice> v[seqlen];
514 }
515
516 Example of an unnamed variant:
517
518 struct {
519 enum : uint2_t { a, b, c, d } choice;
520 /* Unrelated fields can be added between the variant and its tag */
521 int32_t somevalue;
522 variant <choice> {
523 uint32_t a;
524 uint64_t b;
525 short c;
526 struct {
527 unsigned int field1;
528 uint64_t field2;
529 } d;
530 } s;
531 }
532
533 Example of an unnamed variant within an array:
534
535 struct {
536 enum : uint2_t { a, b, c } choice;
537 variant <choice> {
538 uint32_t a;
539 uint64_t b;
540 short c;
541 } v[10];
542 }
543
544 Example of a variant type definition within a structure, where the defined type
545 is then declared within an array of structures. This variant refers to a tag
546 located in an upper static scope. This example clearly shows that a variant
547 type definition referring to the tag "x" uses the closest preceding field from
548 the static scope of the type definition.
549
550 struct {
551 enum : uint2_t { a, b, c, d } x;
552
553 typedef variant <x> { /*
554 * "x" refers to the preceding "x" enumeration in the
555 * static scope of the type definition.
556 */
557 uint32_t a;
558 uint64_t b;
559 short c;
560 } example_variant;
561
562 struct {
563 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
564 example_variant v; /*
565 * "v" uses the "enum : uint2_t { a, b, c, d }"
566 * tag.
567 */
568 } a[10];
569 }
570
571 4.2.3 Arrays
572
573 Arrays are fixed-length. Their length is declared in the type
574 declaration within the meta-data. They contain an array of "inner type"
575 elements, which can refer to any type not containing the type of the
576 array being declared (no circular dependency). The length is the number
577 of elements in an array.
578
579 TSDL meta-data representation of a named array:
580
581 typedef elem_type name[length];
582
583 A nameless array can be declared as a field type within a structure, e.g.:
584
585 uint8_t field_name[10];
586
587 Arrays are always aligned on their element alignment requirement.
588
589 4.2.4 Sequences
590
591 Sequences are dynamically-sized arrays. They refer to a a "length"
592 unsigned integer field, which must appear in either the same static scope,
593 prior to the sequence field (in field declaration order), in an upper
594 static scope, or in an upper dynamic scope (see Section 7.3.2). This
595 length field represents the number of elements in the sequence. The
596 sequence per se is an array of "inner type" elements.
597
598 TSDL meta-data representation for a sequence type definition:
599
600 struct {
601 unsigned int length_field;
602 typedef elem_type typename[length_field];
603 typename seq_field_name;
604 }
605
606 A sequence can also be declared as a field type, e.g.:
607
608 struct {
609 unsigned int length_field;
610 long seq_field_name[length_field];
611 }
612
613 Multiple sequences can refer to the same length field, and these length
614 fields can be in a different upper dynamic scope:
615
616 e.g., assuming the stream.event.header defines:
617
618 stream {
619 ...
620 id = 1;
621 event.header := struct {
622 uint16_t seq_len;
623 };
624 };
625
626 event {
627 ...
628 stream_id = 1;
629 fields := struct {
630 long seq_a[stream.event.header.seq_len];
631 char seq_b[stream.event.header.seq_len];
632 };
633 };
634
635 The sequence elements follow the "array" specifications.
636
637 4.2.5 Strings
638
639 Strings are an array of bytes of variable size and are terminated by a '\0'
640 "NULL" character. Their encoding is described in the TSDL meta-data. In
641 absence of encoding attribute information, the default encoding is
642 UTF-8.
643
644 TSDL meta-data representation of a named string type:
645
646 typealias string {
647 encoding = UTF8 OR ASCII;
648 } := name;
649
650 A nameless string type can be declared as a field type:
651
652 string field_name; /* Use default UTF8 encoding */
653
654 Strings are always aligned on byte size.
655
656 5. Event Packet Header
657
658 The event packet header consists of two parts: the "event packet header"
659 is the same for all streams of a trace. The second part, the "event
660 packet context", is described on a per-stream basis. Both are described
661 in the TSDL meta-data. The packets are aligned on architecture-page-sized
662 addresses.
663
664 Event packet header (all fields are optional, specified by TSDL meta-data):
665
666 - Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
667 CTF packet. This magic number is optional, but when present, it should
668 come at the very beginning of the packet.
669 - Trace UUID, used to ensure the event packet match the meta-data used.
670 (note: we cannot use a meta-data checksum in every cases instead of a
671 UUID because meta-data can be appended to while tracing is active)
672 This field is optional.
673 - Stream ID, used as reference to stream description in meta-data.
674 This field is optional if there is only one stream description in the
675 meta-data, but becomes required if there are more than one stream in
676 the TSDL meta-data description.
677
678 Event packet context (all fields are optional, specified by TSDL meta-data):
679
680 - Event packet content size (in bits).
681 - Event packet size (in bits, includes padding).
682 - Event packet content checksum. Checksum excludes the event packet
683 header.
684 - Per-stream event packet sequence count (to deal with UDP packet loss). The
685 number of significant sequence counter bits should also be present, so
686 wrap-arounds are dealt with correctly.
687 - Time-stamp at the beginning and time-stamp at the end of the event packet.
688 Both timestamps are written in the packet header, but sampled respectively
689 while (or before) writing the first event and while (or after) writing the
690 last event in the packet. The inclusive range between these timestamps should
691 include all event timestamps assigned to events contained within the packet.
692 - Events discarded count
693 - Snapshot of a per-stream free-running counter, counting the number of
694 events discarded that were supposed to be written in the stream prior to
695 the first event in the event packet.
696 * Note: producer-consumer buffer full condition should fill the current
697 event packet with padding so we know exactly where events have been
698 discarded.
699 - Lossless compression scheme used for the event packet content. Applied
700 directly to raw data. New types of compression can be added in following
701 versions of the format.
702 0: no compression scheme
703 1: bzip2
704 2: gzip
705 3: xz
706 - Cypher used for the event packet content. Applied after compression.
707 0: no encryption
708 1: AES
709 - Checksum scheme used for the event packet content. Applied after encryption.
710 0: no checksum
711 1: md5
712 2: sha1
713 3: crc32
714
715 5.1 Event Packet Header Description
716
717 The event packet header layout is indicated by the trace packet.header
718 field. Here is a recommended structure type for the packet header with
719 the fields typically expected (although these fields are each optional):
720
721 struct event_packet_header {
722 uint32_t magic;
723 uint8_t uuid[16];
724 uint32_t stream_id;
725 };
726
727 trace {
728 ...
729 packet.header := struct event_packet_header;
730 };
731
732 If the magic number is not present, tools such as "file" will have no
733 mean to discover the file type.
734
735 If the uuid is not present, no validation that the meta-data actually
736 corresponds to the stream is performed.
737
738 If the stream_id packet header field is missing, the trace can only
739 contain a single stream. Its "id" field can be left out, and its events
740 don't need to declare a "stream_id" field.
741
742
743 5.2 Event Packet Context Description
744
745 Event packet context example. These are declared within the stream declaration
746 in the meta-data. All these fields are optional. If the packet size field is
747 missing, the whole stream only contains a single packet. If the content
748 size field is missing, the packet is filled (no padding). The content
749 and packet sizes include all headers.
750
751 An example event packet context type:
752
753 struct event_packet_context {
754 uint64_t timestamp_begin;
755 uint64_t timestamp_end;
756 uint32_t checksum;
757 uint32_t stream_packet_count;
758 uint32_t events_discarded;
759 uint32_t cpu_id;
760 uint32_t/uint16_t content_size;
761 uint32_t/uint16_t packet_size;
762 uint8_t compression_scheme;
763 uint8_t encryption_scheme;
764 uint8_t checksum_scheme;
765 };
766
767
768 6. Event Structure
769
770 The overall structure of an event is:
771
772 1 - Stream Packet Context (as specified by the stream meta-data)
773 2 - Event Header (as specified by the stream meta-data)
774 3 - Stream Event Context (as specified by the stream meta-data)
775 4 - Event Context (as specified by the event meta-data)
776 5 - Event Payload (as specified by the event meta-data)
777
778 This structure defines an implicit dynamic scoping, where variants
779 located in inner structures (those with a higher number in the listing
780 above) can refer to the fields of outer structures (with lower number in
781 the listing above). See Section 7.3 TSDL Scopes for more detail.
782
783 6.1 Event Header
784
785 Event headers can be described within the meta-data. We hereby propose, as an
786 example, two types of events headers. Type 1 accommodates streams with less than
787 31 event IDs. Type 2 accommodates streams with 31 or more event IDs.
788
789 One major factor can vary between streams: the number of event IDs assigned to
790 a stream. Luckily, this information tends to stay relatively constant (modulo
791 event registration while trace is being recorded), so we can specify different
792 representations for streams containing few event IDs and streams containing
793 many event IDs, so we end up representing the event ID and time-stamp as
794 densely as possible in each case.
795
796 The header is extended in the rare occasions where the information cannot be
797 represented in the ranges available in the standard event header. They are also
798 used in the rare occasions where the data required for a field could not be
799 collected: the flag corresponding to the missing field within the missing_fields
800 array is then set to 1.
801
802 Types uintX_t represent an X-bit unsigned integer, as declared with
803 either:
804
805 typealias integer { size = X; align = X; signed = false } := uintX_t;
806
807 or
808
809 typealias integer { size = X; align = 1; signed = false } := uintX_t;
810
811 6.1.1 Type 1 - Few event IDs
812
813 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
814 preference).
815 - Native architecture byte ordering.
816 - For "compact" selection
817 - Fixed size: 32 bits.
818 - For "extended" selection
819 - Size depends on the architecture and variant alignment.
820
821 struct event_header_1 {
822 /*
823 * id: range: 0 - 30.
824 * id 31 is reserved to indicate an extended header.
825 */
826 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
827 variant <id> {
828 struct {
829 uint27_t timestamp;
830 } compact;
831 struct {
832 uint32_t id; /* 32-bit event IDs */
833 uint64_t timestamp; /* 64-bit timestamps */
834 } extended;
835 } v;
836 } align(32); /* or align(8) */
837
838
839 6.1.2 Type 2 - Many event IDs
840
841 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
842 preference).
843 - Native architecture byte ordering.
844 - For "compact" selection
845 - Size depends on the architecture and variant alignment.
846 - For "extended" selection
847 - Size depends on the architecture and variant alignment.
848
849 struct event_header_2 {
850 /*
851 * id: range: 0 - 65534.
852 * id 65535 is reserved to indicate an extended header.
853 */
854 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
855 variant <id> {
856 struct {
857 uint32_t timestamp;
858 } compact;
859 struct {
860 uint32_t id; /* 32-bit event IDs */
861 uint64_t timestamp; /* 64-bit timestamps */
862 } extended;
863 } v;
864 } align(16); /* or align(8) */
865
866
867 6.2 Event Context
868
869 The event context contains information relative to the current event.
870 The choice and meaning of this information is specified by the TSDL
871 stream and event meta-data descriptions. The stream context is applied
872 to all events within the stream. The stream context structure follows
873 the event header. The event context is applied to specific events. Its
874 structure follows the stream context structure.
875
876 An example of stream-level event context is to save the event payload size with
877 each event, or to save the current PID with each event. These are declared
878 within the stream declaration within the meta-data:
879
880 stream {
881 ...
882 event.context := struct {
883 uint pid;
884 uint16_t payload_size;
885 };
886 };
887
888 An example of event-specific event context is to declare a bitmap of missing
889 fields, only appended after the stream event context if the extended event
890 header is selected. NR_FIELDS is the number of fields within the event (a
891 numeric value).
892
893 event {
894 context = struct {
895 variant <id> {
896 struct { } compact;
897 struct {
898 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
899 } extended;
900 } v;
901 };
902 ...
903 }
904
905 6.3 Event Payload
906
907 An event payload contains fields specific to a given event type. The fields
908 belonging to an event type are described in the event-specific meta-data
909 within a structure type.
910
911 6.3.1 Padding
912
913 No padding at the end of the event payload. This differs from the ISO/C standard
914 for structures, but follows the CTF standard for structures. In a trace, even
915 though it makes sense to align the beginning of a structure, it really makes no
916 sense to add padding at the end of the structure, because structures are usually
917 not followed by a structure of the same type.
918
919 This trick can be done by adding a zero-length "end" field at the end of the C
920 structures, and by using the offset of this field rather than using sizeof()
921 when calculating the size of a structure (see Appendix "A. Helper macros").
922
923 6.3.2 Alignment
924
925 The event payload is aligned on the largest alignment required by types
926 contained within the payload. (This follows the ISO/C standard for structures)
927
928
929 7. Trace Stream Description Language (TSDL)
930
931 The Trace Stream Description Language (TSDL) allows expression of the
932 binary trace streams layout in a C99-like Domain Specific Language
933 (DSL).
934
935
936 7.1 Meta-data
937
938 The trace stream layout description is located in the trace meta-data.
939 The meta-data is itself located in a stream identified by its name:
940 "metadata".
941
942 The meta-data description can be expressed in two different formats:
943 text-only and packet-based. The text-only description facilitates
944 generation of meta-data and provides a convenient way to enter the
945 meta-data information by hand. The packet-based meta-data provides the
946 CTF stream packet facilities (checksumming, compression, encryption,
947 network-readiness) for meta-data stream generated and transported by a
948 tracer.
949
950 The text-only meta-data file is a plain-text TSDL description. This file
951 must begin with the following characters to identify the file as a CTF
952 TSDL text-based metadata file (without the double-quotes) :
953
954 "/* CTF"
955
956 It must be followed by a space, and the version of the specification
957 followed by the CTF trace, e.g.:
958
959 " 1.8"
960
961 These characters allow automated discovery of file type and CTF
962 specification version. They are interpreted as a the beginning of a
963 comment by the TSDL metadata parser. The comment can be continued to
964 contain extra commented characters before it is closed.
965
966 The packet-based meta-data is made of "meta-data packets", which each
967 start with a meta-data packet header. The packet-based meta-data
968 description is detected by reading the magic number "0x75D11D57" at the
969 beginning of the file. This magic number is also used to detect the
970 endianness of the architecture by trying to read the CTF magic number
971 and its counterpart in reversed endianness. The events within the
972 meta-data stream have no event header nor event context. Each event only
973 contains a "sequence" payload, which is a sequence of bits using the
974 "trace.packet.header.content_size" field as a placeholder for its length
975 (the packet header size should be substracted). The formatting of this
976 sequence of bits is a plain-text representation of the TSDL description.
977 Each meta-data packet start with a special packet header, specific to
978 the meta-data stream, which contains, exactly:
979
980 struct metadata_packet_header {
981 uint32_t magic; /* 0x75D11D57 */
982 uint8_t uuid[16]; /* Unique Universal Identifier */
983 uint32_t checksum; /* 0 if unused */
984 uint32_t content_size; /* in bits */
985 uint32_t packet_size; /* in bits */
986 uint8_t compression_scheme; /* 0 if unused */
987 uint8_t encryption_scheme; /* 0 if unused */
988 uint8_t checksum_scheme; /* 0 if unused */
989 uint8_t major; /* CTF spec version major number */
990 uint8_t minor; /* CTF spec version minor number */
991 };
992
993 The packet-based meta-data can be converted to a text-only meta-data by
994 concatenating all the strings in contains.
995
996 In the textual representation of the meta-data, the text contained
997 within "/*" and "*/", as well as within "//" and end of line, are
998 treated as comments. Boolean values can be represented as true, TRUE,
999 or 1 for true, and false, FALSE, or 0 for false. Within the string-based
1000 meta-data description, the trace UUID is represented as a string of
1001 hexadecimal digits and dashes "-". In the event packet header, the trace
1002 UUID is represented as an array of bytes.
1003
1004
1005 7.2 Declaration vs Definition
1006
1007 A declaration associates a layout to a type, without specifying where
1008 this type is located in the event structure hierarchy (see Section 6).
1009 This therefore includes typedef, typealias, as well as all type
1010 specifiers. In certain circumstances (typedef, structure field and
1011 variant field), a declaration is followed by a declarator, which specify
1012 the newly defined type name (for typedef), or the field name (for
1013 declarations located within structure and variants). Array and sequence,
1014 declared with square brackets ("[" "]"), are part of the declarator,
1015 similarly to C99. The enumeration base type is specified by
1016 ": enum_base", which is part of the type specifier. The variant tag
1017 name, specified between "<" ">", is also part of the type specifier.
1018
1019 A definition associates a type to a location in the event structure
1020 hierarchy (see Section 6). This association is denoted by ":=", as shown
1021 in Section 7.3.
1022
1023
1024 7.3 TSDL Scopes
1025
1026 TSDL uses three different types of scoping: a lexical scope is used for
1027 declarations and type definitions, and static and dynamic scopes are
1028 used for variants references to tag fields (with relative and absolute
1029 path lookups) and for sequence references to length fields.
1030
1031 7.3.1 Lexical Scope
1032
1033 Each of "trace", "env", "stream", "event", "struct" and "variant" have
1034 their own nestable declaration scope, within which types can be declared
1035 using "typedef" and "typealias". A root declaration scope also contains
1036 all declarations located outside of any of the aforementioned
1037 declarations. An inner declaration scope can refer to type declared
1038 within its container lexical scope prior to the inner declaration scope.
1039 Redefinition of a typedef or typealias is not valid, although hiding an
1040 upper scope typedef or typealias is allowed within a sub-scope.
1041
1042 7.3.2 Static and Dynamic Scopes
1043
1044 A local static scope consists in the scope generated by the declaration
1045 of fields within a compound type. A static scope is a local static scope
1046 augmented with the nested sub-static-scopes it contains.
1047
1048 A dynamic scope consists in the static scope augmented with the
1049 implicit event structure definition hierarchy presented at Section 6.
1050
1051 Multiple declarations of the same field name within a local static scope
1052 is not valid. It is however valid to re-use the same field name in
1053 different local scopes.
1054
1055 Nested static and dynamic scopes form lookup paths. These are used for
1056 variant tag and sequence length references. They are used at the variant
1057 and sequence definition site to look up the location of the tag field
1058 associated with a variant, and to lookup up the location of the length
1059 field associated with a sequence.
1060
1061 Variants and sequences can refer to a tag field either using a relative
1062 path or an absolute path. The relative path is relative to the scope in
1063 which the variant or sequence performing the lookup is located.
1064 Relative paths are only allowed to lookup within the same static scope,
1065 which includes its nested static scopes. Lookups targeting parent static
1066 scopes need to be performed with an absolute path.
1067
1068 Absolute path lookups use the full path including the dynamic scope
1069 followed by a "." and then the static scope. Therefore, variants (or
1070 sequences) in lower levels in the dynamic scope (e.g. event context) can
1071 refer to a tag (or length) field located in upper levels (e.g. in the
1072 event header) by specifying, in this case, the associated tag with
1073 <stream.event.header.field_name>. This allows, for instance, the event
1074 context to define a variant referring to the "id" field of the event
1075 header as selector.
1076
1077 The dynamic scope prefixes are thus:
1078
1079 - Trace Environment: <env. >,
1080 - Trace Packet Header: <trace.packet.header. >,
1081 - Stream Packet Context: <stream.packet.context. >,
1082 - Event Header: <stream.event.header. >,
1083 - Stream Event Context: <stream.event.context. >,
1084 - Event Context: <event.context. >,
1085 - Event Payload: <event.fields. >.
1086
1087
1088 The target dynamic scope must be specified explicitly when referring to
1089 a field outside of the static scope (absolute scope reference). No
1090 conflict can occur between relative and dynamic paths, because the
1091 keywords "trace", "stream", and "event" are reserved, and thus
1092 not permitted as field names. It is recommended that field names
1093 clashing with CTF and C99 reserved keywords use an underscore prefix to
1094 eliminate the risk of generating a description containing an invalid
1095 field name. Consequently, fields starting with an underscore should have
1096 their leading underscore removed by the CTF trace readers.
1097
1098
1099 The information available in the dynamic scopes can be thought of as the
1100 current tracing context. At trace production, information about the
1101 current context is saved into the specified scope field levels. At trace
1102 consumption, for each event, the current trace context is therefore
1103 readable by accessing the upper dynamic scopes.
1104
1105
1106 7.4 TSDL Examples
1107
1108 The grammar representing the TSDL meta-data is presented in Appendix C.
1109 TSDL Grammar. This section presents a rather lighter reading that
1110 consists in examples of TSDL meta-data, with template values.
1111
1112 The stream "id" can be left out if there is only one stream in the
1113 trace. The event "id" field can be left out if there is only one event
1114 in a stream.
1115
1116 trace {
1117 major = value; /* CTF spec version major number */
1118 minor = value; /* CTF spec version minor number */
1119 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
1120 byte_order = be OR le; /* Endianness (required) */
1121 packet.header := struct {
1122 uint32_t magic;
1123 uint8_t uuid[16];
1124 uint32_t stream_id;
1125 };
1126 };
1127
1128 /*
1129 * The "env" (environment) scope contains assignment expressions. The
1130 * field names and content are implementation-defined.
1131 */
1132 env {
1133 pid = value; /* example */
1134 proc_name = "name"; /* example */
1135 ...
1136 };
1137
1138 stream {
1139 id = stream_id;
1140 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
1141 event.header := event_header_1 OR event_header_2;
1142 event.context := struct {
1143 ...
1144 };
1145 packet.context := struct {
1146 ...
1147 };
1148 };
1149
1150 event {
1151 name = "event_name";
1152 id = value; /* Numeric identifier within the stream */
1153 stream_id = stream_id;
1154 loglevel = value;
1155 context := struct {
1156 ...
1157 };
1158 fields := struct {
1159 ...
1160 };
1161 };
1162
1163 /* More detail on types in section 4. Types */
1164
1165 /*
1166 * Named types:
1167 *
1168 * Type declarations behave similarly to the C standard.
1169 */
1170
1171 typedef aliased_type_specifiers new_type_declarators;
1172
1173 /* e.g.: typedef struct example new_type_name[10]; */
1174
1175 /*
1176 * typealias
1177 *
1178 * The "typealias" declaration can be used to give a name (including
1179 * pointer declarator specifier) to a type. It should also be used to
1180 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1181 * Typealias is a superset of "typedef": it also allows assignment of a
1182 * simple variable identifier to a type.
1183 */
1184
1185 typealias type_class {
1186 ...
1187 } := type_specifiers type_declarator;
1188
1189 /*
1190 * e.g.:
1191 * typealias integer {
1192 * size = 32;
1193 * align = 32;
1194 * signed = false;
1195 * } := struct page *;
1196 *
1197 * typealias integer {
1198 * size = 32;
1199 * align = 32;
1200 * signed = true;
1201 * } := int;
1202 */
1203
1204 struct name {
1205 ...
1206 };
1207
1208 variant name {
1209 ...
1210 };
1211
1212 enum name : integer_type {
1213 ...
1214 };
1215
1216
1217 /*
1218 * Unnamed types, contained within compound type fields, typedef or typealias.
1219 */
1220
1221 struct {
1222 ...
1223 }
1224
1225 struct {
1226 ...
1227 } align(value)
1228
1229 variant {
1230 ...
1231 }
1232
1233 enum : integer_type {
1234 ...
1235 }
1236
1237 typedef type new_type[length];
1238
1239 struct {
1240 type field_name[length];
1241 }
1242
1243 typedef type new_type[length_type];
1244
1245 struct {
1246 type field_name[length_type];
1247 }
1248
1249 integer {
1250 ...
1251 }
1252
1253 floating_point {
1254 ...
1255 }
1256
1257 struct {
1258 integer_type field_name:size; /* GNU/C bitfield */
1259 }
1260
1261 struct {
1262 string field_name;
1263 }
1264
1265
1266 8. Clocks
1267
1268 Clock metadata allows to describe the clock topology of the system, as
1269 well as to detail each clock parameter. In absence of clock description,
1270 it is assumed that all fields named "timestamp" use the same clock
1271 source, which increments once per nanosecond.
1272
1273 Describing a clock and how it is used by streams is threefold: first,
1274 the clock and clock topology should be described in a "clock"
1275 description block, e.g.:
1276
1277 clock {
1278 name = cycle_counter_sync;
1279 uuid = "62189bee-96dc-11e0-91a8-cfa3d89f3923";
1280 description = "Cycle counter synchronized across CPUs";
1281 freq = 1000000000; /* frequency, in Hz */
1282 /* precision in seconds is: 1000 * (1/freq) */
1283 precision = 1000;
1284 /*
1285 * clock value offset from Epoch is:
1286 * offset_s + (offset * (1/freq))
1287 */
1288 offset_s = 1326476837;
1289 offset = 897235420;
1290 absolute = FALSE;
1291 };
1292
1293 The mandatory "name" field specifies the name of the clock identifier,
1294 which can later be used as a reference. The optional field "uuid" is the
1295 unique identifier of the clock. It can be used to correlate different
1296 traces that use the same clock. An optional textual description string
1297 can be added with the "description" field. The "freq" field is the
1298 initial frequency of the clock, in Hz. If the "freq" field is not
1299 present, the frequency is assumed to be 1000000000 (providing clock
1300 increment of 1 ns). The optional "precision" field details the
1301 uncertainty on the clock measurements, in (1/freq) units. The "offset_s"
1302 and "offset" fields indicate the offset from POSIX.1 Epoch, 1970-01-01
1303 00:00:00 +0000 (UTC), to the zero of value of the clock. The "offset_s"
1304 field is in seconds. The "offset" field is in (1/freq) units. If any of
1305 the "offset_s" or "offset" field is not present, it is assigned the 0
1306 value. The field "absolute" is TRUE if the clock is a global reference
1307 across different clock uuid (e.g. NTP time). Otherwise, "absolute" is
1308 FALSE, and the clock can be considered as synchronized only with other
1309 clocks that have the same uuid.
1310
1311
1312 Secondly, a reference to this clock should be added within an integer
1313 type:
1314
1315 typealias integer {
1316 size = 64; align = 1; signed = false;
1317 map = clock.cycle_counter_sync.value;
1318 } := uint64_ccnt_t;
1319
1320 Thirdly, stream declarations can reference the clock they use as a
1321 time-stamp source:
1322
1323 struct packet_context {
1324 uint64_ccnt_t ccnt_begin;
1325 uint64_ccnt_t ccnt_end;
1326 /* ... */
1327 };
1328
1329 stream {
1330 /* ... */
1331 event.header := struct {
1332 uint64_ccnt_t timestamp;
1333 /* ... */
1334 }
1335 packet.context := struct packet_context;
1336 };
1337
1338 For a N-bit integer type referring to a clock, if the integer overflows
1339 compared to the N low order bits of the clock prior value, then it is
1340 assumed that one, and only one, overflow occurred. It is therefore
1341 important that events encoding time on a small number of bits happen
1342 frequently enough to detect when more than one N-bit overflow occurs.
1343
1344 In a packet context, clock field names ending with "_begin" and "_end"
1345 have a special meaning: this refers to the time-stamps at, respectively,
1346 the beginning and the end of each packet.
1347
1348
1349 A. Helper macros
1350
1351 The two following macros keep track of the size of a GNU/C structure without
1352 padding at the end by placing HEADER_END as the last field. A one byte end field
1353 is used for C90 compatibility (C99 flexible arrays could be used here). Note
1354 that this does not affect the effective structure size, which should always be
1355 calculated with the header_sizeof() helper.
1356
1357 #define HEADER_END char end_field
1358 #define header_sizeof(type) offsetof(typeof(type), end_field)
1359
1360
1361 B. Stream Header Rationale
1362
1363 An event stream is divided in contiguous event packets of variable size. These
1364 subdivisions allow the trace analyzer to perform a fast binary search by time
1365 within the stream (typically requiring to index only the event packet headers)
1366 without reading the whole stream. These subdivisions have a variable size to
1367 eliminate the need to transfer the event packet padding when partially filled
1368 event packets must be sent when streaming a trace for live viewing/analysis.
1369 An event packet can contain a certain amount of padding at the end. Dividing
1370 streams into event packets is also useful for network streaming over UDP and
1371 flight recorder mode tracing (a whole event packet can be swapped out of the
1372 buffer atomically for reading).
1373
1374 The stream header is repeated at the beginning of each event packet to allow
1375 flexibility in terms of:
1376
1377 - streaming support,
1378 - allowing arbitrary buffers to be discarded without making the trace
1379 unreadable,
1380 - allow UDP packet loss handling by either dealing with missing event packet
1381 or asking for re-transmission.
1382 - transparently support flight recorder mode,
1383 - transparently support crash dump.
1384
1385
1386 C. TSDL Grammar
1387
1388 /*
1389 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
1390 *
1391 * Inspired from the C99 grammar:
1392 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
1393 * and c++1x grammar (draft)
1394 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
1395 *
1396 * Specialized for CTF needs by including only constant and declarations from
1397 * C99 (excluding function declarations), and by adding support for variants,
1398 * sequences and CTF-specific specifiers. Enumeration container types
1399 * semantic is inspired from c++1x enum-base.
1400 */
1401
1402 1) Lexical grammar
1403
1404 1.1) Lexical elements
1405
1406 token:
1407 keyword
1408 identifier
1409 constant
1410 string-literal
1411 punctuator
1412
1413 1.2) Keywords
1414
1415 keyword: is one of
1416
1417 align
1418 const
1419 char
1420 clock
1421 double
1422 enum
1423 env
1424 event
1425 floating_point
1426 float
1427 integer
1428 int
1429 long
1430 short
1431 signed
1432 stream
1433 string
1434 struct
1435 trace
1436 typealias
1437 typedef
1438 unsigned
1439 variant
1440 void
1441 _Bool
1442 _Complex
1443 _Imaginary
1444
1445
1446 1.3) Identifiers
1447
1448 identifier:
1449 identifier-nondigit
1450 identifier identifier-nondigit
1451 identifier digit
1452
1453 identifier-nondigit:
1454 nondigit
1455 universal-character-name
1456 any other implementation-defined characters
1457
1458 nondigit:
1459 _
1460 [a-zA-Z] /* regular expression */
1461
1462 digit:
1463 [0-9] /* regular expression */
1464
1465 1.4) Universal character names
1466
1467 universal-character-name:
1468 \u hex-quad
1469 \U hex-quad hex-quad
1470
1471 hex-quad:
1472 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1473
1474 1.5) Constants
1475
1476 constant:
1477 integer-constant
1478 enumeration-constant
1479 character-constant
1480
1481 integer-constant:
1482 decimal-constant integer-suffix-opt
1483 octal-constant integer-suffix-opt
1484 hexadecimal-constant integer-suffix-opt
1485
1486 decimal-constant:
1487 nonzero-digit
1488 decimal-constant digit
1489
1490 octal-constant:
1491 0
1492 octal-constant octal-digit
1493
1494 hexadecimal-constant:
1495 hexadecimal-prefix hexadecimal-digit
1496 hexadecimal-constant hexadecimal-digit
1497
1498 hexadecimal-prefix:
1499 0x
1500 0X
1501
1502 nonzero-digit:
1503 [1-9]
1504
1505 integer-suffix:
1506 unsigned-suffix long-suffix-opt
1507 unsigned-suffix long-long-suffix
1508 long-suffix unsigned-suffix-opt
1509 long-long-suffix unsigned-suffix-opt
1510
1511 unsigned-suffix:
1512 u
1513 U
1514
1515 long-suffix:
1516 l
1517 L
1518
1519 long-long-suffix:
1520 ll
1521 LL
1522
1523 enumeration-constant:
1524 identifier
1525 string-literal
1526
1527 character-constant:
1528 ' c-char-sequence '
1529 L' c-char-sequence '
1530
1531 c-char-sequence:
1532 c-char
1533 c-char-sequence c-char
1534
1535 c-char:
1536 any member of source charset except single-quote ('), backslash
1537 (\), or new-line character.
1538 escape-sequence
1539
1540 escape-sequence:
1541 simple-escape-sequence
1542 octal-escape-sequence
1543 hexadecimal-escape-sequence
1544 universal-character-name
1545
1546 simple-escape-sequence: one of
1547 \' \" \? \\ \a \b \f \n \r \t \v
1548
1549 octal-escape-sequence:
1550 \ octal-digit
1551 \ octal-digit octal-digit
1552 \ octal-digit octal-digit octal-digit
1553
1554 hexadecimal-escape-sequence:
1555 \x hexadecimal-digit
1556 hexadecimal-escape-sequence hexadecimal-digit
1557
1558 1.6) String literals
1559
1560 string-literal:
1561 " s-char-sequence-opt "
1562 L" s-char-sequence-opt "
1563
1564 s-char-sequence:
1565 s-char
1566 s-char-sequence s-char
1567
1568 s-char:
1569 any member of source charset except double-quote ("), backslash
1570 (\), or new-line character.
1571 escape-sequence
1572
1573 1.7) Punctuators
1574
1575 punctuator: one of
1576 [ ] ( ) { } . -> * + - < > : ; ... = ,
1577
1578
1579 2) Phrase structure grammar
1580
1581 primary-expression:
1582 identifier
1583 constant
1584 string-literal
1585 ( unary-expression )
1586
1587 postfix-expression:
1588 primary-expression
1589 postfix-expression [ unary-expression ]
1590 postfix-expression . identifier
1591 postfix-expressoin -> identifier
1592
1593 unary-expression:
1594 postfix-expression
1595 unary-operator postfix-expression
1596
1597 unary-operator: one of
1598 + -
1599
1600 assignment-operator:
1601 =
1602
1603 type-assignment-operator:
1604 :=
1605
1606 constant-expression-range:
1607 unary-expression ... unary-expression
1608
1609 2.2) Declarations:
1610
1611 declaration:
1612 declaration-specifiers declarator-list-opt ;
1613 ctf-specifier ;
1614
1615 declaration-specifiers:
1616 storage-class-specifier declaration-specifiers-opt
1617 type-specifier declaration-specifiers-opt
1618 type-qualifier declaration-specifiers-opt
1619
1620 declarator-list:
1621 declarator
1622 declarator-list , declarator
1623
1624 abstract-declarator-list:
1625 abstract-declarator
1626 abstract-declarator-list , abstract-declarator
1627
1628 storage-class-specifier:
1629 typedef
1630
1631 type-specifier:
1632 void
1633 char
1634 short
1635 int
1636 long
1637 float
1638 double
1639 signed
1640 unsigned
1641 _Bool
1642 _Complex
1643 _Imaginary
1644 struct-specifier
1645 variant-specifier
1646 enum-specifier
1647 typedef-name
1648 ctf-type-specifier
1649
1650 align-attribute:
1651 align ( unary-expression )
1652
1653 struct-specifier:
1654 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1655 struct identifier align-attribute-opt
1656
1657 struct-or-variant-declaration-list:
1658 struct-or-variant-declaration
1659 struct-or-variant-declaration-list struct-or-variant-declaration
1660
1661 struct-or-variant-declaration:
1662 specifier-qualifier-list struct-or-variant-declarator-list ;
1663 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
1664 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1665 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
1666
1667 specifier-qualifier-list:
1668 type-specifier specifier-qualifier-list-opt
1669 type-qualifier specifier-qualifier-list-opt
1670
1671 struct-or-variant-declarator-list:
1672 struct-or-variant-declarator
1673 struct-or-variant-declarator-list , struct-or-variant-declarator
1674
1675 struct-or-variant-declarator:
1676 declarator
1677 declarator-opt : unary-expression
1678
1679 variant-specifier:
1680 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1681 variant identifier variant-tag
1682
1683 variant-tag:
1684 < unary-expression >
1685
1686 enum-specifier:
1687 enum identifier-opt { enumerator-list }
1688 enum identifier-opt { enumerator-list , }
1689 enum identifier
1690 enum identifier-opt : declaration-specifiers { enumerator-list }
1691 enum identifier-opt : declaration-specifiers { enumerator-list , }
1692
1693 enumerator-list:
1694 enumerator
1695 enumerator-list , enumerator
1696
1697 enumerator:
1698 enumeration-constant
1699 enumeration-constant assignment-operator unary-expression
1700 enumeration-constant assignment-operator constant-expression-range
1701
1702 type-qualifier:
1703 const
1704
1705 declarator:
1706 pointer-opt direct-declarator
1707
1708 direct-declarator:
1709 identifier
1710 ( declarator )
1711 direct-declarator [ unary-expression ]
1712
1713 abstract-declarator:
1714 pointer-opt direct-abstract-declarator
1715
1716 direct-abstract-declarator:
1717 identifier-opt
1718 ( abstract-declarator )
1719 direct-abstract-declarator [ unary-expression ]
1720 direct-abstract-declarator [ ]
1721
1722 pointer:
1723 * type-qualifier-list-opt
1724 * type-qualifier-list-opt pointer
1725
1726 type-qualifier-list:
1727 type-qualifier
1728 type-qualifier-list type-qualifier
1729
1730 typedef-name:
1731 identifier
1732
1733 2.3) CTF-specific declarations
1734
1735 ctf-specifier:
1736 clock { ctf-assignment-expression-list-opt }
1737 event { ctf-assignment-expression-list-opt }
1738 stream { ctf-assignment-expression-list-opt }
1739 env { ctf-assignment-expression-list-opt }
1740 trace { ctf-assignment-expression-list-opt }
1741 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1742 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
1743
1744 ctf-type-specifier:
1745 floating_point { ctf-assignment-expression-list-opt }
1746 integer { ctf-assignment-expression-list-opt }
1747 string { ctf-assignment-expression-list-opt }
1748 string
1749
1750 ctf-assignment-expression-list:
1751 ctf-assignment-expression ;
1752 ctf-assignment-expression-list ctf-assignment-expression ;
1753
1754 ctf-assignment-expression:
1755 unary-expression assignment-operator unary-expression
1756 unary-expression type-assignment-operator type-specifier
1757 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
1758 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1759 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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