Update struct event_packet_context
[ctf.git] / common-trace-format-specification.txt
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4dfca05b 1Common Trace Format (CTF) Specification (pre-v1.8)
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2
3Mathieu Desnoyers, EfficiOS Inc.
4
339a7dde 5The goal of the present document is to specify a trace format that suits the
cc089c3a 6needs of the embedded, telecom, high-performance and kernel communities. It is
5ba9f198 7based on the Common Trace Format Requirements (v1.4) document. It is designed to
cc089c3a 8allow traces to be natively generated by the Linux kernel, Linux user-space
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9applications written in C/C++, and hardware components. One major element of
10CTF is the Trace Stream Description Language (TSDL) which flexibility
11enables description of various binary trace stream layouts.
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12
13The 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
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17
18A reference implementation of a library to read and write this trace format is
19being implemented within the BabelTrace project, a converter between trace
20formats. 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
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25The CE Workgroup of the Linux Foundation, Ericsson, and EfficiOS have
26sponsored this work.
27
5ba9f198 28
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29Table of Contents
30
311. Preliminary definitions
322. High-level representation of a trace
333. Event stream
344. 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
444.2 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
505. Event Packet Header
51 5.1 Event Packet Header Description
52 5.2 Event Packet Context Description
536. 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
617. 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
37ab95c3 66 7.3.2 Static and Dynamic Scopes
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67 7.4 TSDL Examples
68
69
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701. Preliminary definitions
71
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72 - Event Trace: An ordered sequence of events.
73 - Event Stream: An ordered sequence of events, containing a subset of the
74 trace event types.
75 - Event Packet: A sequence of physically contiguous events within an event
76 stream.
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77 - Event: This is the basic entry in a trace. (aka: a trace record).
78 - An event identifier (ID) relates to the class (a type) of event within
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79 an event stream.
80 e.g. event: irq_entry.
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81 - An event (or event record) relates to a specific instance of an event
82 class.
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83 e.g. event: irq_entry, at time X, on CPU Y
84 - Source Architecture: Architecture writing the trace.
85 - Reader Architecture: Architecture reading the trace.
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86
87
882. High-level representation of a trace
89
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90A trace is divided into multiple event streams. Each event stream contains a
91subset of the trace event types.
5ba9f198 92
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93The final output of the trace, after its generation and optional transport over
94the network, is expected to be either on permanent or temporary storage in a
95virtual file system. Because each event stream is appended to while a trace is
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96being recorded, each is associated with a distinct set of files for
97output. Therefore, a stored trace can be represented as a directory
98containing zero, one or more files per stream.
5ba9f198 99
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100Meta-data description associated with the trace contains information on
101trace event types expressed in the Trace Stream Description Language
102(TSDL). This language describes:
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103
104- Trace version.
105- Types available.
6672e9e1 106- Per-trace event header description.
3bf79539 107- Per-stream event header description.
6672e9e1 108- Per-stream event context description.
5ba9f198 109- Per-event
3bf79539 110 - Event type to stream mapping.
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111 - Event type to name mapping.
112 - Event type to ID mapping.
6672e9e1 113 - Event context description.
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114 - Event fields description.
115
116
3bf79539 1173. Event stream
5ba9f198 118
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119An event stream can be divided into contiguous event packets of variable
120size. These subdivisions have a variable size. An event packet can
121contain a certain amount of padding at the end. The stream header is
122repeated at the beginning of each event packet. The rationale for the
123event stream design choices is explained in Appendix B. Stream Header
124Rationale.
5ba9f198 125
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126The event stream header will therefore be referred to as the "event packet
127header" throughout the rest of this document.
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128
129
1304. Types
131
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132Types are organized as type classes. Each type class belong to either of two
133kind of types: basic types or compound types.
134
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1354.1 Basic types
136
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137A basic type is a scalar type, as described in this section. It includes
138integers, GNU/C bitfields, enumerations, and floating point values.
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139
1404.1.1 Type inheritance
141
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142Type specifications can be inherited to allow deriving types from a
143type class. For example, see the uint32_t named type derived from the "integer"
144type class below ("Integers" section). Types have a precise binary
145representation in the trace. A type class has methods to read and write these
146types, but must be derived into a type to be usable in an event field.
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147
1484.1.2 Alignment
149
150We define "byte-packed" types as aligned on the byte size, namely 8-bit.
151We define "bit-packed" types as following on the next bit, as defined by the
370eae99 152"Integers" section.
5ba9f198 153
6672e9e1 154Each basic type must specify its alignment, in bits. Examples of
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155possible alignments are: bit-packed (align = 1), byte-packed (align =
1568), or word-aligned (e.g. align = 32 or align = 64). The choice depends
157on the architecture preference and compactness vs performance trade-offs
158of the implementation. Architectures providing fast unaligned write
159byte-packed basic types to save space, aligning each type on byte
160boundaries (8-bit). Architectures with slow unaligned writes align types
161on specific alignment values. If no specific alignment is declared for a
162type, it is assumed to be bit-packed for integers with size not multiple
163of 8 bits and for gcc bitfields. All other basic types are byte-packed
164by default. It is however recommended to always specify the alignment
165explicitly. Alignment values must be power of two. Compound types are
166aligned as specified in their individual specification.
5ba9f198 167
6672e9e1 168TSDL meta-data attribute representation of a specific alignment:
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169
170 align = value; /* value in bits */
171
1724.1.3 Byte order
173
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174By default, the native endianness of the source architecture the trace is used.
175Byte order can be overridden for a basic type by specifying a "byte_order"
176attribute. Typical use-case is to specify the network byte order (big endian:
177"be") to save data captured from the network into the trace without conversion.
178If not specified, the byte order is native.
5ba9f198 179
6672e9e1 180TSDL meta-data representation:
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181
182 byte_order = native OR network OR be OR le; /* network and be are aliases */
183
1844.1.4 Size
185
186Type size, in bits, for integers and floats is that returned by "sizeof()" in C
187multiplied by CHAR_BIT.
188We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed
189to 8 bits for cross-endianness compatibility.
190
6672e9e1 191TSDL meta-data representation:
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192
193 size = value; (value is in bits)
194
1954.1.5 Integers
196
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197Signed integers are represented in two-complement. Integer alignment,
198size, signedness and byte ordering are defined in the TSDL meta-data.
199Integers aligned on byte size (8-bit) and with length multiple of byte
200size (8-bit) correspond to the C99 standard integers. In addition,
201integers with alignment and/or size that are _not_ a multiple of the
202byte size are permitted; these correspond to the C99 standard bitfields,
203with the added specification that the CTF integer bitfields have a fixed
204binary representation. A MIT-licensed reference implementation of the
205CTF portable bitfields is available at:
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206
207 http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h
208
209Binary representation of integers:
210
211- On little and big endian:
212 - Within a byte, high bits correspond to an integer high bits, and low bits
213 correspond to low bits.
214- On little endian:
215 - Integer across multiple bytes are placed from the less significant to the
216 most significant.
217 - Consecutive integers are placed from lower bits to higher bits (even within
218 a byte).
219- On big endian:
220 - Integer across multiple bytes are placed from the most significant to the
221 less significant.
222 - Consecutive integers are placed from higher bits to lower bits (even within
223 a byte).
224
225This binary representation is derived from the bitfield implementation in GCC
226for little and big endian. However, contrary to what GCC does, integers can
6672e9e1 227cross units boundaries (no padding is required). Padding can be explicitly
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228added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed.
229
6672e9e1 230TSDL meta-data representation:
5ba9f198 231
80fd2569 232 integer {
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233 signed = true OR false; /* default false */
234 byte_order = native OR network OR be OR le; /* default native */
235 size = value; /* value in bits, no default */
236 align = value; /* value in bits */
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237 /* based used for pretty-printing output, default: decimal. */
238 base = decimal OR dec OR OR d OR i OR u OR 10 OR hexadecimal OR hex OR x OR X OR p OR 16
239 OR octal OR oct OR o OR 8 OR binary OR b OR 2;
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240 /* character encoding, default: none */
241 encoding = none or UTF8 or ASCII;
2152348f 242 }
5ba9f198 243
80fd2569 244Example of type inheritance (creation of a uint32_t named type):
5ba9f198 245
359894ac 246typealias integer {
9e4e34e9 247 size = 32;
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248 signed = false;
249 align = 32;
38b8da21 250} := uint32_t;
5ba9f198 251
80fd2569 252Definition of a named 5-bit signed bitfield:
5ba9f198 253
359894ac 254typealias integer {
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255 size = 5;
256 signed = true;
257 align = 1;
38b8da21 258} := int5_t;
5ba9f198 259
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260The character encoding field can be used to specify that the integer
261must be printed as a text character when read. e.g.:
262
263typealias integer {
264 size = 8;
265 align = 8;
266 signed = false;
267 encoding = UTF8;
268} := utf_char;
269
270
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2714.1.6 GNU/C bitfields
272
273The GNU/C bitfields follow closely the integer representation, with a
274particularity on alignment: if a bitfield cannot fit in the current unit, the
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275unit is padded and the bitfield starts at the following unit. The unit size is
276defined by the size of the type "unit_type".
5ba9f198 277
6672e9e1 278TSDL meta-data representation:
80fd2569 279
d674f4b8 280 unit_type name:size;
80fd2569 281
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282As an example, the following structure declared in C compiled by GCC:
283
284struct example {
285 short a:12;
286 short b:5;
287};
288
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289The example structure is aligned on the largest element (short). The second
290bitfield would be aligned on the next unit boundary, because it would not fit in
291the current unit.
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292
2934.1.7 Floating point
294
6672e9e1 295The floating point values byte ordering is defined in the TSDL meta-data.
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296
297Floating point values follow the IEEE 754-2008 standard interchange formats.
298Description of the floating point values include the exponent and mantissa size
299in bits. Some requirements are imposed on the floating point values:
300
301- FLT_RADIX must be 2.
302- mant_dig is the number of digits represented in the mantissa. It is specified
303 by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and
304 LDBL_MANT_DIG as defined by <float.h>.
305- exp_dig is the number of digits represented in the exponent. Given that
306 mant_dig is one bit more than its actual size in bits (leading 1 is not
307 needed) and also given that the sign bit always takes one bit, exp_dig can be
308 specified as:
309
310 - sizeof(float) * CHAR_BIT - FLT_MANT_DIG
311 - sizeof(double) * CHAR_BIT - DBL_MANT_DIG
312 - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG
313
6672e9e1 314TSDL meta-data representation:
5ba9f198 315
80fd2569 316floating_point {
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317 exp_dig = value;
318 mant_dig = value;
319 byte_order = native OR network OR be OR le;
320 align = value;
2152348f 321}
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322
323Example of type inheritance:
324
359894ac 325typealias floating_point {
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326 exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */
327 mant_dig = 24; /* FLT_MANT_DIG */
328 byte_order = native;
ec4404a7 329 align = 32;
38b8da21 330} := float;
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331
332TODO: define NaN, +inf, -inf behavior.
333
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334Bit-packed, byte-packed or larger alignments can be used for floating
335point values, similarly to integers.
336
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3374.1.8 Enumerations
338
339Enumerations are a mapping between an integer type and a table of strings. The
340numerical representation of the enumeration follows the integer type specified
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341by the meta-data. The enumeration mapping table is detailed in the enumeration
342description within the meta-data. The mapping table maps inclusive value
343ranges (or single values) to strings. Instead of being limited to simple
3bf79539 344"value -> string" mappings, these enumerations map
80fd2569 345"[ start_value ... end_value ] -> string", which map inclusive ranges of
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346values to strings. An enumeration from the C language can be represented in
347this format by having the same start_value and end_value for each element, which
348is in fact a range of size 1. This single-value range is supported without
4767a9e7 349repeating the start and end values with the value = string declaration.
80fd2569 350
a9b83695 351enum name : integer_type {
359894ac 352 somestring = start_value1 ... end_value1,
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353 "other string" = start_value2 ... end_value2,
354 yet_another_string, /* will be assigned to end_value2 + 1 */
355 "some other string" = value,
356 ...
357};
358
359If the values are omitted, the enumeration starts at 0 and increment of 1 for
360each entry:
361
a9b83695 362enum name : unsigned int {
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363 ZERO,
364 ONE,
365 TWO,
366 TEN = 10,
367 ELEVEN,
3bf79539 368};
5ba9f198 369
80fd2569 370Overlapping ranges within a single enumeration are implementation defined.
5ba9f198 371
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372A nameless enumeration can be declared as a field type or as part of a typedef:
373
a9b83695 374enum : integer_type {
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375 ...
376}
377
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378Enumerations omitting the container type ": integer_type" use the "int"
379type (for compatibility with C99). The "int" type must be previously
380declared. E.g.:
381
382typealias integer { size = 32; align = 32; signed = true } := int;
383
384enum {
385 ...
386}
387
1fad7a85 388
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3894.2 Compound types
390
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391Compound are aggregation of type declarations. Compound types include
392structures, variant, arrays, sequences, and strings.
393
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3944.2.1 Structures
395
396Structures are aligned on the largest alignment required by basic types
397contained within the structure. (This follows the ISO/C standard for structures)
398
6672e9e1 399TSDL meta-data representation of a named structure:
5ba9f198 400
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401struct name {
402 field_type field_name;
403 field_type field_name;
404 ...
405};
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406
407Example:
408
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409struct example {
410 integer { /* Nameless type */
411 size = 16;
412 signed = true;
413 align = 16;
414 } first_field_name;
6672e9e1 415 uint64_t second_field_name; /* Named type declared in the meta-data */
3bf79539 416};
5ba9f198 417
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418The fields are placed in a sequence next to each other. They each
419possess a field name, which is a unique identifier within the structure.
420The identifier is not allowed to use any reserved keyword
421(see Section C.1.2). Replacing reserved keywords with
422underscore-prefixed field names is recommended.
5ba9f198 423
2152348f 424A nameless structure can be declared as a field type or as part of a typedef:
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425
426struct {
427 ...
2152348f 428}
80fd2569 429
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430Alignment for a structure compound type can be forced to a minimum value
431by adding an "align" specifier after the declaration of a structure
432body. This attribute is read as: align(value). The value is specified in
433bits. The structure will be aligned on the maximum value between this
434attribute and the alignment required by the basic types contained within
435the structure. e.g.
436
437struct {
438 ...
439} align(32)
440
77a98c82 4414.2.2 Variants (Discriminated/Tagged Unions)
fcba70d4 442
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443A CTF variant is a selection between different types. A CTF variant must
444always be defined within the scope of a structure or within fields
445contained within a structure (defined recursively). A "tag" enumeration
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446field must appear in either the same static scope, prior to the variant
447field (in field declaration order), in an upper static scope , or in an
448upper dynamic scope (see Section 7.3.2). The type selection is indicated
449by the mapping from the enumeration value to the string used as variant
450type selector. The field to use as tag is specified by the "tag_field",
451specified between "< >" after the "variant" keyword for unnamed
452variants, and after "variant name" for named variants.
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453
454The alignment of the variant is the alignment of the type as selected by the tag
455value for the specific instance of the variant. The alignment of the type
456containing the variant is independent of the variant alignment. The size of the
457variant is the size as selected by the tag value for the specific instance of
458the variant.
459
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460Each variant type selector possess a field name, which is a unique
461identifier within the variant. The identifier is not allowed to use any
462reserved keyword (see Section C.1.2). Replacing reserved keywords with
463underscore-prefixed field names is recommended.
464
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465A named variant declaration followed by its definition within a structure
466declaration:
467
468variant name {
469 field_type sel1;
470 field_type sel2;
471 field_type sel3;
472 ...
473};
474
475struct {
a9b83695 476 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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477 ...
478 variant name <tag_field> v;
479}
480
481An unnamed variant definition within a structure is expressed by the following
6672e9e1 482TSDL meta-data:
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483
484struct {
a9b83695 485 enum : integer_type { sel1, sel2, sel3, ... } tag_field;
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486 ...
487 variant <tag_field> {
488 field_type sel1;
489 field_type sel2;
490 field_type sel3;
491 ...
492 } v;
493}
494
495Example of a named variant within a sequence that refers to a single tag field:
496
497variant example {
498 uint32_t a;
499 uint64_t b;
500 short c;
501};
502
503struct {
a9b83695 504 enum : uint2_t { a, b, c } choice;
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505 unsigned int seqlen;
506 variant example <choice> v[seqlen];
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507}
508
509Example of an unnamed variant:
510
511struct {
a9b83695 512 enum : uint2_t { a, b, c, d } choice;
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513 /* Unrelated fields can be added between the variant and its tag */
514 int32_t somevalue;
515 variant <choice> {
516 uint32_t a;
517 uint64_t b;
518 short c;
519 struct {
520 unsigned int field1;
521 uint64_t field2;
522 } d;
523 } s;
524}
525
526Example of an unnamed variant within an array:
527
528struct {
a9b83695 529 enum : uint2_t { a, b, c } choice;
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530 variant <choice> {
531 uint32_t a;
532 uint64_t b;
533 short c;
15850440 534 } v[10];
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535}
536
537Example of a variant type definition within a structure, where the defined type
538is then declared within an array of structures. This variant refers to a tag
37ab95c3 539located in an upper static scope. This example clearly shows that a variant
fcba70d4 540type definition referring to the tag "x" uses the closest preceding field from
37ab95c3 541the static scope of the type definition.
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542
543struct {
a9b83695 544 enum : uint2_t { a, b, c, d } x;
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545
546 typedef variant <x> { /*
547 * "x" refers to the preceding "x" enumeration in the
37ab95c3 548 * static scope of the type definition.
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549 */
550 uint32_t a;
551 uint64_t b;
552 short c;
553 } example_variant;
554
555 struct {
a9b83695 556 enum : int { x, y, z } x; /* This enumeration is not used by "v". */
fcba70d4 557 example_variant v; /*
a9b83695 558 * "v" uses the "enum : uint2_t { a, b, c, d }"
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559 * tag.
560 */
561 } a[10];
562}
563
5644.2.3 Arrays
5ba9f198 565
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566Arrays are fixed-length. Their length is declared in the type
567declaration within the meta-data. They contain an array of "inner type"
568elements, which can refer to any type not containing the type of the
569array being declared (no circular dependency). The length is the number
570of elements in an array.
5ba9f198 571
6672e9e1 572TSDL meta-data representation of a named array:
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573
574typedef elem_type name[length];
5ba9f198 575
2152348f 576A nameless array can be declared as a field type within a structure, e.g.:
5ba9f198 577
2152348f 578 uint8_t field_name[10];
80fd2569 579
ec4404a7 580Arrays are always aligned on their element alignment requirement.
5ba9f198 581
fcba70d4 5824.2.4 Sequences
5ba9f198 583
1ab22b2a 584Sequences are dynamically-sized arrays. They refer to a a "length"
37ab95c3 585unsigned integer field, which must appear in either the same static scope,
1ab22b2a 586prior to the sequence field (in field declaration order), in an upper
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587static scope, or in an upper dynamic scope (see Section 7.3.2). This
588length field represents the number of elements in the sequence. The
589sequence per se is an array of "inner type" elements.
5ba9f198 590
1ab22b2a 591TSDL meta-data representation for a sequence type definition:
80fd2569 592
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593struct {
594 unsigned int length_field;
595 typedef elem_type typename[length_field];
596 typename seq_field_name;
597}
598
599A sequence can also be declared as a field type, e.g.:
80fd2569 600
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601struct {
602 unsigned int length_field;
603 long seq_field_name[length_field];
604}
80fd2569 605
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606Multiple sequences can refer to the same length field, and these length
607fields can be in a different upper dynamic scope:
608
609e.g., assuming the stream.event.header defines:
610
611stream {
612 ...
613 id = 1;
614 event.header := struct {
615 uint16_t seq_len;
616 };
617};
618
619event {
620 ...
621 stream_id = 1;
622 fields := struct {
623 long seq_a[stream.event.header.seq_len];
624 char seq_b[stream.event.header.seq_len];
625 };
626};
80fd2569 627
1ab22b2a 628The sequence elements follow the "array" specifications.
5ba9f198 629
fcba70d4 6304.2.5 Strings
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631
632Strings are an array of bytes of variable size and are terminated by a '\0'
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633"NULL" character. Their encoding is described in the TSDL meta-data. In
634absence of encoding attribute information, the default encoding is
635UTF-8.
5ba9f198 636
6672e9e1 637TSDL meta-data representation of a named string type:
80fd2569 638
359894ac 639typealias string {
5ba9f198 640 encoding = UTF8 OR ASCII;
38b8da21 641} := name;
5ba9f198 642
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643A nameless string type can be declared as a field type:
644
645string field_name; /* Use default UTF8 encoding */
5ba9f198 646
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647Strings are always aligned on byte size.
648
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6495. Event Packet Header
650
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651The event packet header consists of two parts: the "event packet header"
652is the same for all streams of a trace. The second part, the "event
653packet context", is described on a per-stream basis. Both are described
654in the TSDL meta-data. The packets are aligned on architecture-page-sized
655addresses.
3bf79539 656
6672e9e1 657Event packet header (all fields are optional, specified by TSDL meta-data):
3bf79539 658
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659- Magic number (CTF magic number: 0xC1FC1FC1) specifies that this is a
660 CTF packet. This magic number is optional, but when present, it should
661 come at the very beginning of the packet.
662- Trace UUID, used to ensure the event packet match the meta-data used.
663 (note: we cannot use a meta-data checksum in every cases instead of a
664 UUID because meta-data can be appended to while tracing is active)
665 This field is optional.
666- Stream ID, used as reference to stream description in meta-data.
667 This field is optional if there is only one stream description in the
668 meta-data, but becomes required if there are more than one stream in
669 the TSDL meta-data description.
3bf79539 670
6672e9e1 671Event packet context (all fields are optional, specified by TSDL meta-data):
3bf79539 672
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673- Event packet content size (in bits).
674- Event packet size (in bits, includes padding).
cda89682 675- Event packet content checksum. Checksum excludes the event packet
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676 header.
677- Per-stream event packet sequence count (to deal with UDP packet loss). The
678 number of significant sequence counter bits should also be present, so
b11853af 679 wrap-arounds are dealt with correctly.
6672e9e1 680- Time-stamp at the beginning and time-stamp at the end of the event packet.
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681 Both timestamps are written in the packet header, but sampled respectively
682 while (or before) writing the first event and while (or after) writing the
683 last event in the packet. The inclusive range between these timestamps should
684 include all event timestamps assigned to events contained within the packet.
5ba9f198 685- Events discarded count
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686 - Snapshot of a per-stream free-running counter, counting the number of
687 events discarded that were supposed to be written in the stream prior to
688 the first event in the event packet.
5ba9f198 689 * Note: producer-consumer buffer full condition should fill the current
3bf79539 690 event packet with padding so we know exactly where events have been
5ba9f198 691 discarded.
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692- Lossless compression scheme used for the event packet content. Applied
693 directly to raw data. New types of compression can be added in following
694 versions of the format.
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695 0: no compression scheme
696 1: bzip2
697 2: gzip
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698 3: xz
699- Cypher used for the event packet content. Applied after compression.
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700 0: no encryption
701 1: AES
3bf79539 702- Checksum scheme used for the event packet content. Applied after encryption.
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703 0: no checksum
704 1: md5
705 2: sha1
706 3: crc32
707
6672e9e1 7085.1 Event Packet Header Description
3bf79539 709
fc5425db 710The event packet header layout is indicated by the trace packet.header
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711field. Here is a recommended structure type for the packet header with
712the fields typically expected (although these fields are each optional):
fc5425db 713
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714struct event_packet_header {
715 uint32_t magic;
3fde5da1 716 uint8_t uuid[16];
3bf79539 717 uint32_t stream_id;
80fd2569 718};
5ba9f198 719
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720trace {
721 ...
722 packet.header := struct event_packet_header;
723};
724
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725If the magic number is not present, tools such as "file" will have no
726mean to discover the file type.
727
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728If the uuid is not present, no validation that the meta-data actually
729corresponds to the stream is performed.
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730
731If the stream_id packet header field is missing, the trace can only
732contain a single stream. Its "id" field can be left out, and its events
733don't need to declare a "stream_id" field.
734
735
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7365.2 Event Packet Context Description
737
738Event packet context example. These are declared within the stream declaration
6672e9e1 739in the meta-data. All these fields are optional. If the packet size field is
6a7c61df 740missing, the whole stream only contains a single packet. If the content
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741size field is missing, the packet is filled (no padding). The content
742and packet sizes include all headers.
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743
744An example event packet context type:
745
80fd2569 746struct event_packet_context {
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747 uint64_t timestamp_begin;
748 uint64_t timestamp_end;
749 uint32_t checksum;
750 uint32_t stream_packet_count;
751 uint32_t events_discarded;
752 uint32_t cpu_id;
753 uint32_t/uint16_t content_size;
754 uint32_t/uint16_t packet_size;
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755 uint8_t compression_scheme;
756 uint8_t encryption_scheme;
3b0f8e4d 757 uint8_t checksum_scheme;
3bf79539 758};
5ba9f198 759
fcba70d4 760
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7616. Event Structure
762
763The overall structure of an event is:
764
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7651 - Stream Packet Context (as specified by the stream meta-data)
766 2 - Event Header (as specified by the stream meta-data)
767 3 - Stream Event Context (as specified by the stream meta-data)
768 4 - Event Context (as specified by the event meta-data)
769 5 - Event Payload (as specified by the event meta-data)
5ba9f198 770
fdf2bb05 771This structure defines an implicit dynamic scoping, where variants
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772located in inner structures (those with a higher number in the listing
773above) can refer to the fields of outer structures (with lower number in
6c7226e9 774the listing above). See Section 7.3 TSDL Scopes for more detail.
5ba9f198 775
fdf2bb05 7766.1 Event Header
fcba70d4 777
6672e9e1 778Event headers can be described within the meta-data. We hereby propose, as an
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779example, two types of events headers. Type 1 accommodates streams with less than
78031 event IDs. Type 2 accommodates streams with 31 or more event IDs.
5ba9f198 781
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782One major factor can vary between streams: the number of event IDs assigned to
783a stream. Luckily, this information tends to stay relatively constant (modulo
5ba9f198 784event registration while trace is being recorded), so we can specify different
3bf79539 785representations for streams containing few event IDs and streams containing
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786many event IDs, so we end up representing the event ID and time-stamp as
787densely as possible in each case.
5ba9f198 788
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789The header is extended in the rare occasions where the information cannot be
790represented in the ranges available in the standard event header. They are also
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791used in the rare occasions where the data required for a field could not be
792collected: the flag corresponding to the missing field within the missing_fields
793array is then set to 1.
5ba9f198 794
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795Types uintX_t represent an X-bit unsigned integer, as declared with
796either:
5ba9f198 797
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798 typealias integer { size = X; align = X; signed = false } := uintX_t;
799
800 or
801
802 typealias integer { size = X; align = 1; signed = false } := uintX_t;
5ba9f198 803
fdf2bb05 8046.1.1 Type 1 - Few event IDs
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805
806 - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture
807 preference).
5ba9f198 808 - Native architecture byte ordering.
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809 - For "compact" selection
810 - Fixed size: 32 bits.
811 - For "extended" selection
812 - Size depends on the architecture and variant alignment.
5ba9f198 813
80fd2569 814struct event_header_1 {
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815 /*
816 * id: range: 0 - 30.
817 * id 31 is reserved to indicate an extended header.
818 */
a9b83695 819 enum : uint5_t { compact = 0 ... 30, extended = 31 } id;
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820 variant <id> {
821 struct {
822 uint27_t timestamp;
823 } compact;
824 struct {
825 uint32_t id; /* 32-bit event IDs */
826 uint64_t timestamp; /* 64-bit timestamps */
827 } extended;
828 } v;
cb108fea 829} align(32); /* or align(8) */
5ba9f198 830
5ba9f198 831
fdf2bb05 8326.1.2 Type 2 - Many event IDs
5ba9f198 833
fcba70d4 834 - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture
5ba9f198 835 preference).
5ba9f198 836 - Native architecture byte ordering.
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837 - For "compact" selection
838 - Size depends on the architecture and variant alignment.
839 - For "extended" selection
840 - Size depends on the architecture and variant alignment.
5ba9f198 841
80fd2569 842struct event_header_2 {
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843 /*
844 * id: range: 0 - 65534.
845 * id 65535 is reserved to indicate an extended header.
846 */
a9b83695 847 enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;
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848 variant <id> {
849 struct {
850 uint32_t timestamp;
851 } compact;
852 struct {
853 uint32_t id; /* 32-bit event IDs */
854 uint64_t timestamp; /* 64-bit timestamps */
855 } extended;
856 } v;
cb108fea 857} align(16); /* or align(8) */
5ba9f198 858
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859
8606.2 Event Context
861
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862The event context contains information relative to the current event.
863The choice and meaning of this information is specified by the TSDL
864stream and event meta-data descriptions. The stream context is applied
865to all events within the stream. The stream context structure follows
866the event header. The event context is applied to specific events. Its
867structure follows the stream context structure.
5ba9f198 868
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869An example of stream-level event context is to save the event payload size with
870each event, or to save the current PID with each event. These are declared
6672e9e1 871within the stream declaration within the meta-data:
5ba9f198 872
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873 stream {
874 ...
6672e9e1 875 event.context := struct {
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876 uint pid;
877 uint16_t payload_size;
6672e9e1 878 };
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879 };
880
881An example of event-specific event context is to declare a bitmap of missing
882fields, only appended after the stream event context if the extended event
883header is selected. NR_FIELDS is the number of fields within the event (a
884numeric value).
5ba9f198 885
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886 event {
887 context = struct {
888 variant <id> {
889 struct { } compact;
890 struct {
891 uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */
892 } extended;
893 } v;
894 };
895 ...
896 }
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897
8986.3 Event Payload
899
900An event payload contains fields specific to a given event type. The fields
6672e9e1 901belonging to an event type are described in the event-specific meta-data
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902within a structure type.
903
9046.3.1 Padding
905
906No padding at the end of the event payload. This differs from the ISO/C standard
907for structures, but follows the CTF standard for structures. In a trace, even
908though it makes sense to align the beginning of a structure, it really makes no
909sense to add padding at the end of the structure, because structures are usually
910not followed by a structure of the same type.
911
912This trick can be done by adding a zero-length "end" field at the end of the C
913structures, and by using the offset of this field rather than using sizeof()
3bf79539 914when calculating the size of a structure (see Appendix "A. Helper macros").
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915
9166.3.2 Alignment
917
918The event payload is aligned on the largest alignment required by types
919contained within the payload. (This follows the ISO/C standard for structures)
920
921
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9227. Trace Stream Description Language (TSDL)
923
924The Trace Stream Description Language (TSDL) allows expression of the
925binary trace streams layout in a C99-like Domain Specific Language
926(DSL).
927
928
6672e9e1 9297.1 Meta-data
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MD
930
931The trace stream layout description is located in the trace meta-data.
932The meta-data is itself located in a stream identified by its name:
933"metadata".
5ba9f198 934
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935The meta-data description can be expressed in two different formats:
936text-only and packet-based. The text-only description facilitates
937generation of meta-data and provides a convenient way to enter the
938meta-data information by hand. The packet-based meta-data provides the
939CTF stream packet facilities (checksumming, compression, encryption,
940network-readiness) for meta-data stream generated and transported by a
941tracer.
942
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943The text-only meta-data file is a plain-text TSDL description. This file
944must begin with the following characters to identify the file as a CTF
9486a18c 945TSDL text-based metadata file (without the double-quotes) :
1b4d35eb 946
ec2b4db8 947"/* CTF"
1b4d35eb 948
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949It must be followed by a space, and the version of the specification
950followed by the CTF trace, e.g.:
951
952" 1.8"
953
954These characters allow automated discovery of file type and CTF
955specification version. They are interpreted as a the beginning of a
956comment by the TSDL metadata parser. The comment can be continued to
957contain extra commented characters before it is closed.
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958
959The packet-based meta-data is made of "meta-data packets", which each
960start with a meta-data packet header. The packet-based meta-data
961description is detected by reading the magic number "0x75D11D57" at the
962beginning of the file. This magic number is also used to detect the
963endianness of the architecture by trying to read the CTF magic number
964and its counterpart in reversed endianness. The events within the
965meta-data stream have no event header nor event context. Each event only
5ae2352d 966contains a "sequence" payload, which is a sequence of bits using the
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967"trace.packet.header.content_size" field as a placeholder for its length
968(the packet header size should be substracted). The formatting of this
969sequence of bits is a plain-text representation of the TSDL description.
970Each meta-data packet start with a special packet header, specific to
971the meta-data stream, which contains, exactly:
6672e9e1
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972
973struct metadata_packet_header {
2daeaa3a 974 uint32_t magic; /* 0x75D11D57 */
3fde5da1 975 uint8_t uuid[16]; /* Unique Universal Identifier */
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976 uint32_t checksum; /* 0 if unused */
977 uint32_t content_size; /* in bits */
978 uint32_t packet_size; /* in bits */
979 uint8_t compression_scheme; /* 0 if unused */
980 uint8_t encryption_scheme; /* 0 if unused */
981 uint8_t checksum_scheme; /* 0 if unused */
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982 uint8_t major; /* CTF spec version major number */
983 uint8_t minor; /* CTF spec version minor number */
6672e9e1
MD
984};
985
986The packet-based meta-data can be converted to a text-only meta-data by
987concatenating all the strings in contains.
4fafe1ad 988
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989In the textual representation of the meta-data, the text contained
990within "/*" and "*/", as well as within "//" and end of line, are
991treated as comments. Boolean values can be represented as true, TRUE,
992or 1 for true, and false, FALSE, or 0 for false. Within the string-based
993meta-data description, the trace UUID is represented as a string of
994hexadecimal digits and dashes "-". In the event packet header, the trace
995UUID is represented as an array of bytes.
fcba70d4 996
fdf2bb05 997
6c7226e9 9987.2 Declaration vs Definition
fdf2bb05
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999
1000A declaration associates a layout to a type, without specifying where
1001this type is located in the event structure hierarchy (see Section 6).
1002This therefore includes typedef, typealias, as well as all type
1003specifiers. In certain circumstances (typedef, structure field and
1004variant field), a declaration is followed by a declarator, which specify
1005the newly defined type name (for typedef), or the field name (for
1006declarations located within structure and variants). Array and sequence,
1007declared with square brackets ("[" "]"), are part of the declarator,
a9b83695 1008similarly to C99. The enumeration base type is specified by
6c7226e9 1009": enum_base", which is part of the type specifier. The variant tag
a9b83695 1010name, specified between "<" ">", is also part of the type specifier.
fdf2bb05
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1011
1012A definition associates a type to a location in the event structure
b9606a77
MD
1013hierarchy (see Section 6). This association is denoted by ":=", as shown
1014in Section 7.3.
fdf2bb05
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1015
1016
6c7226e9 10177.3 TSDL Scopes
fdf2bb05 1018
37ab95c3
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1019TSDL uses three different types of scoping: a lexical scope is used for
1020declarations and type definitions, and static and dynamic scopes are
1021used for variants references to tag fields (with relative and absolute
1022path lookups) and for sequence references to length fields.
fdf2bb05 1023
6c7226e9 10247.3.1 Lexical Scope
fdf2bb05 1025
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1026Each of "trace", "stream", "event", "struct" and "variant" have their own
1027nestable declaration scope, within which types can be declared using "typedef"
fdf2bb05 1028and "typealias". A root declaration scope also contains all declarations
7d9d7e92 1029located outside of any of the aforementioned declarations. An inner
fdf2bb05 1030declaration scope can refer to type declared within its container
7d9d7e92
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1031lexical scope prior to the inner declaration scope. Redefinition of a
1032typedef or typealias is not valid, although hiding an upper scope
fdf2bb05
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1033typedef or typealias is allowed within a sub-scope.
1034
37ab95c3 10357.3.2 Static and Dynamic Scopes
fdf2bb05 1036
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1037A local static scope consists in the scope generated by the declaration
1038of fields within a compound type. A static scope is a local static scope
1039augmented with the nested sub-static-scopes it contains.
1040
1041A dynamic scope consists in the static scope augmented with the
7d9d7e92 1042implicit event structure definition hierarchy presented at Section 6.
fdf2bb05 1043
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1044Multiple declarations of the same field name within a local static scope
1045is not valid. It is however valid to re-use the same field name in
1046different local scopes.
1047
1048Nested static and dynamic scopes form lookup paths. These are used for
1049variant tag and sequence length references. They are used at the variant
1050and sequence definition site to look up the location of the tag field
1051associated with a variant, and to lookup up the location of the length
1052field associated with a sequence.
1053
1054Variants and sequences can refer to a tag field either using a relative
4cac83ee
MD
1055path or an absolute path. The relative path is relative to the scope in
1056which the variant or sequence performing the lookup is located.
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1057Relative paths are only allowed to lookup within the same static scope,
1058which includes its nested static scopes. Lookups targeting parent static
1059scopes need to be performed with an absolute path.
1060
1061Absolute path lookups use the full path including the dynamic scope
1062followed by a "." and then the static scope. Therefore, variants (or
1063sequences) in lower levels in the dynamic scope (e.g. event context) can
1064refer to a tag (or length) field located in upper levels (e.g. in the
1065event header) by specifying, in this case, the associated tag with
1066<stream.event.header.field_name>. This allows, for instance, the event
1067context to define a variant referring to the "id" field of the event
1068header as selector.
1069
284724ae 1070The dynamic scope prefixes are thus:
fdf2bb05 1071
e0d9e2c7 1072 - Trace Packet Header: <trace.packet.header. >,
7d9d7e92
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1073 - Stream Packet Context: <stream.packet.context. >,
1074 - Event Header: <stream.event.header. >,
1075 - Stream Event Context: <stream.event.context. >,
1076 - Event Context: <event.context. >,
1077 - Event Payload: <event.fields. >.
fdf2bb05 1078
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1079
1080The target dynamic scope must be specified explicitly when referring to
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1081a field outside of the static scope (absolute scope reference). No
1082conflict can occur between relative and dynamic paths, because the
1083keywords "trace", "stream", and "event" are reserved, and thus
1084not permitted as field names. It is recommended that field names
1085clashing with CTF and C99 reserved keywords use an underscore prefix to
1086eliminate the risk of generating a description containing an invalid
1087field name.
fdf2bb05 1088
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1089The information available in the dynamic scopes can be thought of as the
1090current tracing context. At trace production, information about the
1091current context is saved into the specified scope field levels. At trace
1092consumption, for each event, the current trace context is therefore
1093readable by accessing the upper dynamic scopes.
1094
fdf2bb05 1095
6c7226e9 10967.4 TSDL Examples
d285084f 1097
6672e9e1 1098The grammar representing the TSDL meta-data is presented in Appendix C.
7df6b93a 1099TSDL Grammar. This section presents a rather lighter reading that
6672e9e1 1100consists in examples of TSDL meta-data, with template values.
969f30c0 1101
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1102The stream "id" can be left out if there is only one stream in the
1103trace. The event "id" field can be left out if there is only one event
1104in a stream.
1105
5ba9f198 1106trace {
fdf2bb05 1107 major = value; /* Trace format version */
5ba9f198 1108 minor = value;
fdf2bb05 1109 uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */
58997e9e 1110 byte_order = be OR le; /* Endianness (required) */
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1111 packet.header := struct {
1112 uint32_t magic;
3fde5da1 1113 uint8_t uuid[16];
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1114 uint32_t stream_id;
1115 };
3bf79539 1116};
5ba9f198 1117
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1118stream {
1119 id = stream_id;
fdf2bb05 1120 /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */
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1121 event.header := event_header_1 OR event_header_2;
1122 event.context := struct {
77a98c82 1123 ...
3bf79539 1124 };
4fa992a5 1125 packet.context := struct {
77a98c82 1126 ...
3bf79539
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1127 };
1128};
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1129
1130event {
980015f9 1131 name = "event_name";
3bf79539 1132 id = value; /* Numeric identifier within the stream */
67f02e24 1133 stream_id = stream_id;
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1134 loglevel.identifier = "loglevel_identifier";
1135 loglevel.value = value;
4fa992a5 1136 context := struct {
fcba70d4
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1137 ...
1138 };
4fa992a5 1139 fields := struct {
80fd2569
MD
1140 ...
1141 };
3bf79539 1142};
5ba9f198
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1143
1144/* More detail on types in section 4. Types */
1145
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1146/*
1147 * Named types:
1148 *
4fa992a5 1149 * Type declarations behave similarly to the C standard.
3d13ef1a
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1150 */
1151
80af8ac6 1152typedef aliased_type_specifiers new_type_declarators;
2152348f 1153
3d13ef1a 1154/* e.g.: typedef struct example new_type_name[10]; */
80fd2569 1155
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1156/*
1157 * typealias
1158 *
1159 * The "typealias" declaration can be used to give a name (including
80af8ac6
MD
1160 * pointer declarator specifier) to a type. It should also be used to
1161 * map basic C types (float, int, unsigned long, ...) to a CTF type.
1162 * Typealias is a superset of "typedef": it also allows assignment of a
38b8da21 1163 * simple variable identifier to a type.
4fa992a5
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1164 */
1165
1166typealias type_class {
80fd2569 1167 ...
38b8da21 1168} := type_specifiers type_declarator;
2152348f 1169
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1170/*
1171 * e.g.:
4fa992a5 1172 * typealias integer {
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1173 * size = 32;
1174 * align = 32;
1175 * signed = false;
38b8da21 1176 * } := struct page *;
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1177 *
1178 * typealias integer {
1179 * size = 32;
1180 * align = 32;
1181 * signed = true;
38b8da21 1182 * } := int;
3d13ef1a 1183 */
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1184
1185struct name {
3bf79539
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1186 ...
1187};
5ba9f198 1188
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1189variant name {
1190 ...
1191};
1192
a9b83695 1193enum name : integer_type {
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1194 ...
1195};
1196
2152348f 1197
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1198/*
1199 * Unnamed types, contained within compound type fields, typedef or typealias.
1200 */
2152348f 1201
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1202struct {
1203 ...
2152348f 1204}
5ba9f198 1205
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1206struct {
1207 ...
1208} align(value)
1209
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1210variant {
1211 ...
1212}
1213
a9b83695 1214enum : integer_type {
80fd2569 1215 ...
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1216}
1217
1218typedef type new_type[length];
3bf79539 1219
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1220struct {
1221 type field_name[length];
1222}
1223
1224typedef type new_type[length_type];
1225
1226struct {
1227 type field_name[length_type];
1228}
1229
1230integer {
80fd2569 1231 ...
2152348f 1232}
3bf79539 1233
2152348f 1234floating_point {
80fd2569 1235 ...
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1236}
1237
1238struct {
1239 integer_type field_name:size; /* GNU/C bitfield */
1240}
1241
1242struct {
1243 string field_name;
1244}
3bf79539 1245
fcba70d4 1246
3bf79539 1247A. Helper macros
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1248
1249The two following macros keep track of the size of a GNU/C structure without
1250padding at the end by placing HEADER_END as the last field. A one byte end field
1251is used for C90 compatibility (C99 flexible arrays could be used here). Note
1252that this does not affect the effective structure size, which should always be
1253calculated with the header_sizeof() helper.
1254
1255#define HEADER_END char end_field
1256#define header_sizeof(type) offsetof(typeof(type), end_field)
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1257
1258
1259B. Stream Header Rationale
1260
1261An event stream is divided in contiguous event packets of variable size. These
1262subdivisions allow the trace analyzer to perform a fast binary search by time
1263within the stream (typically requiring to index only the event packet headers)
1264without reading the whole stream. These subdivisions have a variable size to
1265eliminate the need to transfer the event packet padding when partially filled
1266event packets must be sent when streaming a trace for live viewing/analysis.
1267An event packet can contain a certain amount of padding at the end. Dividing
1268streams into event packets is also useful for network streaming over UDP and
1269flight recorder mode tracing (a whole event packet can be swapped out of the
1270buffer atomically for reading).
1271
1272The stream header is repeated at the beginning of each event packet to allow
1273flexibility in terms of:
1274
1275 - streaming support,
1276 - allowing arbitrary buffers to be discarded without making the trace
1277 unreadable,
1278 - allow UDP packet loss handling by either dealing with missing event packet
1279 or asking for re-transmission.
1280 - transparently support flight recorder mode,
1281 - transparently support crash dump.
1282
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1283
1284C. TSDL Grammar
fcba70d4 1285
4fa992a5 1286/*
6c7226e9 1287 * Common Trace Format (CTF) Trace Stream Description Language (TSDL) Grammar.
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1288 *
1289 * Inspired from the C99 grammar:
1290 * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A)
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1291 * and c++1x grammar (draft)
1292 * http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3291.pdf (Annex A)
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1293 *
1294 * Specialized for CTF needs by including only constant and declarations from
1295 * C99 (excluding function declarations), and by adding support for variants,
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1296 * sequences and CTF-specific specifiers. Enumeration container types
1297 * semantic is inspired from c++1x enum-base.
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1298 */
1299
13001) Lexical grammar
1301
13021.1) Lexical elements
1303
1304token:
1305 keyword
1306 identifier
1307 constant
1308 string-literal
1309 punctuator
1310
13111.2) Keywords
1312
1313keyword: is one of
1314
ec4404a7 1315align
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MD
1316const
1317char
1318double
1319enum
1320event
1321floating_point
1322float
1323integer
1324int
1325long
1326short
1327signed
1328stream
1329string
1330struct
1331trace
3e1e1a78 1332typealias
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MD
1333typedef
1334unsigned
1335variant
1336void
1337_Bool
1338_Complex
1339_Imaginary
1340
1341
13421.3) Identifiers
1343
1344identifier:
1345 identifier-nondigit
1346 identifier identifier-nondigit
1347 identifier digit
1348
1349identifier-nondigit:
1350 nondigit
1351 universal-character-name
1352 any other implementation-defined characters
1353
1354nondigit:
1355 _
1356 [a-zA-Z] /* regular expression */
1357
1358digit:
1359 [0-9] /* regular expression */
1360
13611.4) Universal character names
1362
1363universal-character-name:
1364 \u hex-quad
1365 \U hex-quad hex-quad
1366
1367hex-quad:
1368 hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
1369
13701.5) Constants
1371
1372constant:
1373 integer-constant
1374 enumeration-constant
1375 character-constant
1376
1377integer-constant:
1378 decimal-constant integer-suffix-opt
1379 octal-constant integer-suffix-opt
1380 hexadecimal-constant integer-suffix-opt
1381
1382decimal-constant:
1383 nonzero-digit
1384 decimal-constant digit
1385
1386octal-constant:
1387 0
1388 octal-constant octal-digit
1389
1390hexadecimal-constant:
1391 hexadecimal-prefix hexadecimal-digit
1392 hexadecimal-constant hexadecimal-digit
1393
1394hexadecimal-prefix:
1395 0x
1396 0X
1397
1398nonzero-digit:
1399 [1-9]
1400
1401integer-suffix:
1402 unsigned-suffix long-suffix-opt
1403 unsigned-suffix long-long-suffix
1404 long-suffix unsigned-suffix-opt
1405 long-long-suffix unsigned-suffix-opt
1406
1407unsigned-suffix:
1408 u
1409 U
1410
1411long-suffix:
1412 l
1413 L
1414
1415long-long-suffix:
1416 ll
1417 LL
1418
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MD
1419enumeration-constant:
1420 identifier
1421 string-literal
1422
1423character-constant:
1424 ' c-char-sequence '
1425 L' c-char-sequence '
1426
1427c-char-sequence:
1428 c-char
1429 c-char-sequence c-char
1430
1431c-char:
1432 any member of source charset except single-quote ('), backslash
1433 (\), or new-line character.
1434 escape-sequence
1435
1436escape-sequence:
1437 simple-escape-sequence
1438 octal-escape-sequence
1439 hexadecimal-escape-sequence
1440 universal-character-name
1441
1442simple-escape-sequence: one of
1443 \' \" \? \\ \a \b \f \n \r \t \v
1444
1445octal-escape-sequence:
1446 \ octal-digit
1447 \ octal-digit octal-digit
1448 \ octal-digit octal-digit octal-digit
1449
1450hexadecimal-escape-sequence:
1451 \x hexadecimal-digit
1452 hexadecimal-escape-sequence hexadecimal-digit
1453
14541.6) String literals
1455
1456string-literal:
1457 " s-char-sequence-opt "
1458 L" s-char-sequence-opt "
1459
1460s-char-sequence:
1461 s-char
1462 s-char-sequence s-char
1463
1464s-char:
1465 any member of source charset except double-quote ("), backslash
1466 (\), or new-line character.
1467 escape-sequence
1468
14691.7) Punctuators
1470
1471punctuator: one of
1472 [ ] ( ) { } . -> * + - < > : ; ... = ,
1473
1474
14752) Phrase structure grammar
1476
1477primary-expression:
1478 identifier
1479 constant
1480 string-literal
1481 ( unary-expression )
1482
1483postfix-expression:
1484 primary-expression
1485 postfix-expression [ unary-expression ]
1486 postfix-expression . identifier
1487 postfix-expressoin -> identifier
1488
1489unary-expression:
1490 postfix-expression
1491 unary-operator postfix-expression
1492
1493unary-operator: one of
1494 + -
1495
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1496assignment-operator:
1497 =
1498
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1499type-assignment-operator:
1500 :=
1501
4fa992a5 1502constant-expression-range:
73d61ac3 1503 unary-expression ... unary-expression
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1504
15052.2) Declarations:
1506
1507declaration:
689e04b4 1508 declaration-specifiers declarator-list-opt ;
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1509 ctf-specifier ;
1510
1511declaration-specifiers:
689e04b4 1512 storage-class-specifier declaration-specifiers-opt
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1513 type-specifier declaration-specifiers-opt
1514 type-qualifier declaration-specifiers-opt
1515
1516declarator-list:
1517 declarator
1518 declarator-list , declarator
1519
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1520abstract-declarator-list:
1521 abstract-declarator
1522 abstract-declarator-list , abstract-declarator
1523
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1524storage-class-specifier:
1525 typedef
1526
1527type-specifier:
1528 void
1529 char
1530 short
1531 int
1532 long
1533 float
1534 double
1535 signed
1536 unsigned
1537 _Bool
1538 _Complex
cfdd51ec 1539 _Imaginary
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1540 struct-specifier
1541 variant-specifier
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1542 enum-specifier
1543 typedef-name
1544 ctf-type-specifier
1545
ec4404a7 1546align-attribute:
73d61ac3 1547 align ( unary-expression )
ec4404a7 1548
4fa992a5 1549struct-specifier:
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1550 struct identifier-opt { struct-or-variant-declaration-list-opt } align-attribute-opt
1551 struct identifier align-attribute-opt
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1552
1553struct-or-variant-declaration-list:
1554 struct-or-variant-declaration
1555 struct-or-variant-declaration-list struct-or-variant-declaration
1556
1557struct-or-variant-declaration:
1558 specifier-qualifier-list struct-or-variant-declarator-list ;
eacb16d1 1559 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list ;
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1560 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list ;
1561 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list ;
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1562
1563specifier-qualifier-list:
1564 type-specifier specifier-qualifier-list-opt
1565 type-qualifier specifier-qualifier-list-opt
1566
1567struct-or-variant-declarator-list:
1568 struct-or-variant-declarator
1569 struct-or-variant-declarator-list , struct-or-variant-declarator
1570
1571struct-or-variant-declarator:
1572 declarator
73d61ac3 1573 declarator-opt : unary-expression
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1574
1575variant-specifier:
1576 variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list }
1577 variant identifier variant-tag
1578
1579variant-tag:
37ab95c3 1580 < unary-expression >
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1581
1582enum-specifier:
1583 enum identifier-opt { enumerator-list }
1584 enum identifier-opt { enumerator-list , }
1585 enum identifier
a9b83695
MD
1586 enum identifier-opt : declaration-specifiers { enumerator-list }
1587 enum identifier-opt : declaration-specifiers { enumerator-list , }
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1588
1589enumerator-list:
1590 enumerator
1591 enumerator-list , enumerator
1592
1593enumerator:
1594 enumeration-constant
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1595 enumeration-constant assignment-operator unary-expression
1596 enumeration-constant assignment-operator constant-expression-range
4fa992a5
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1597
1598type-qualifier:
1599 const
1600
1601declarator:
1602 pointer-opt direct-declarator
1603
1604direct-declarator:
1605 identifier
1606 ( declarator )
1ab22b2a 1607 direct-declarator [ unary-expression ]
4fa992a5 1608
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1609abstract-declarator:
1610 pointer-opt direct-abstract-declarator
1611
1612direct-abstract-declarator:
1613 identifier-opt
1614 ( abstract-declarator )
1ab22b2a 1615 direct-abstract-declarator [ unary-expression ]
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1616 direct-abstract-declarator [ ]
1617
4fa992a5 1618pointer:
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1619 * type-qualifier-list-opt
1620 * type-qualifier-list-opt pointer
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MD
1621
1622type-qualifier-list:
1623 type-qualifier
1624 type-qualifier-list type-qualifier
1625
4fa992a5
MD
1626typedef-name:
1627 identifier
1628
16292.3) CTF-specific declarations
1630
1631ctf-specifier:
1632 event { ctf-assignment-expression-list-opt }
1633 stream { ctf-assignment-expression-list-opt }
1634 trace { ctf-assignment-expression-list-opt }
b12919a5
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1635 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1636 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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1637
1638ctf-type-specifier:
1639 floating_point { ctf-assignment-expression-list-opt }
1640 integer { ctf-assignment-expression-list-opt }
1641 string { ctf-assignment-expression-list-opt }
7609d3c7 1642 string
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1643
1644ctf-assignment-expression-list:
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1645 ctf-assignment-expression ;
1646 ctf-assignment-expression-list ctf-assignment-expression ;
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1647
1648ctf-assignment-expression:
1649 unary-expression assignment-operator unary-expression
1650 unary-expression type-assignment-operator type-specifier
eacb16d1 1651 declaration-specifiers-opt storage-class-specifier declaration-specifiers-opt declarator-list
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1652 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declaration-specifiers abstract-declarator-list
1653 typealias declaration-specifiers abstract-declarator-list type-assignment-operator declarator-list
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