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5ba9f198 | 1 | |
4767a9e7 | 2 | RFC: Common Trace Format (CTF) Proposal (pre-v1.7) |
5ba9f198 MD |
3 | |
4 | Mathieu Desnoyers, EfficiOS Inc. | |
5 | ||
6 | The goal of the present document is to propose a trace format that suits the | |
cc089c3a | 7 | needs of the embedded, telecom, high-performance and kernel communities. It is |
5ba9f198 | 8 | based on the Common Trace Format Requirements (v1.4) document. It is designed to |
cc089c3a MD |
9 | allow traces to be natively generated by the Linux kernel, Linux user-space |
10 | applications written in C/C++, and hardware components. | |
11 | ||
12 | The latest version of this document can be found at: | |
13 | ||
14 | git tree: git://git.efficios.com/ctf.git | |
15 | gitweb: http://git.efficios.com/?p=ctf.git | |
5ba9f198 MD |
16 | |
17 | A reference implementation of a library to read and write this trace format is | |
18 | being implemented within the BabelTrace project, a converter between trace | |
19 | formats. The development tree is available at: | |
20 | ||
21 | git tree: git://git.efficios.com/babeltrace.git | |
22 | gitweb: http://git.efficios.com/?p=babeltrace.git | |
23 | ||
24 | ||
25 | 1. Preliminary definitions | |
26 | ||
3bf79539 MD |
27 | - Event Trace: An ordered sequence of events. |
28 | - Event Stream: An ordered sequence of events, containing a subset of the | |
29 | trace event types. | |
30 | - Event Packet: A sequence of physically contiguous events within an event | |
31 | stream. | |
5ba9f198 MD |
32 | - Event: This is the basic entry in a trace. (aka: a trace record). |
33 | - An event identifier (ID) relates to the class (a type) of event within | |
3bf79539 MD |
34 | an event stream. |
35 | e.g. event: irq_entry. | |
5ba9f198 MD |
36 | - An event (or event record) relates to a specific instance of an event |
37 | class. | |
3bf79539 MD |
38 | e.g. event: irq_entry, at time X, on CPU Y |
39 | - Source Architecture: Architecture writing the trace. | |
40 | - Reader Architecture: Architecture reading the trace. | |
5ba9f198 MD |
41 | |
42 | ||
43 | 2. High-level representation of a trace | |
44 | ||
3bf79539 MD |
45 | A trace is divided into multiple event streams. Each event stream contains a |
46 | subset of the trace event types. | |
5ba9f198 | 47 | |
3bf79539 MD |
48 | The final output of the trace, after its generation and optional transport over |
49 | the network, is expected to be either on permanent or temporary storage in a | |
50 | virtual file system. Because each event stream is appended to while a trace is | |
51 | being recorded, each is associated with a separate file for output. Therefore, | |
52 | a stored trace can be represented as a directory containing one file per stream. | |
5ba9f198 | 53 | |
3bf79539 | 54 | A metadata event stream contains information on trace event types. It describes: |
5ba9f198 MD |
55 | |
56 | - Trace version. | |
57 | - Types available. | |
3bf79539 MD |
58 | - Per-stream event header description. |
59 | - Per-stream event header selection. | |
60 | - Per-stream event context fields. | |
5ba9f198 | 61 | - Per-event |
3bf79539 | 62 | - Event type to stream mapping. |
5ba9f198 MD |
63 | - Event type to name mapping. |
64 | - Event type to ID mapping. | |
65 | - Event fields description. | |
66 | ||
67 | ||
3bf79539 | 68 | 3. Event stream |
5ba9f198 | 69 | |
3bf79539 | 70 | An event stream is divided in contiguous event packets of variable size. These |
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71 | subdivisions have a variable size. An event packet can contain a certain |
72 | amount of padding at the end. The stream header is repeated at the | |
73 | beginning of each event packet. The rationale for the event stream | |
74 | design choices is explained in Appendix B. Stream Header Rationale. | |
5ba9f198 | 75 | |
3bf79539 MD |
76 | The event stream header will therefore be referred to as the "event packet |
77 | header" throughout the rest of this document. | |
5ba9f198 MD |
78 | |
79 | ||
80 | 4. Types | |
81 | ||
1fad7a85 MD |
82 | Types are organized as type classes. Each type class belong to either of two |
83 | kind of types: basic types or compound types. | |
84 | ||
5ba9f198 MD |
85 | 4.1 Basic types |
86 | ||
1fad7a85 MD |
87 | A basic type is a scalar type, as described in this section. It includes |
88 | integers, GNU/C bitfields, enumerations, and floating point values. | |
5ba9f198 MD |
89 | |
90 | 4.1.1 Type inheritance | |
91 | ||
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92 | Type specifications can be inherited to allow deriving types from a |
93 | type class. For example, see the uint32_t named type derived from the "integer" | |
94 | type class below ("Integers" section). Types have a precise binary | |
95 | representation in the trace. A type class has methods to read and write these | |
96 | types, but must be derived into a type to be usable in an event field. | |
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97 | |
98 | 4.1.2 Alignment | |
99 | ||
100 | We define "byte-packed" types as aligned on the byte size, namely 8-bit. | |
101 | We define "bit-packed" types as following on the next bit, as defined by the | |
370eae99 | 102 | "Integers" section. |
5ba9f198 | 103 | |
3bf79539 MD |
104 | All basic types, except bitfields, are either aligned on an architecture-defined |
105 | specific alignment or byte-packed, depending on the architecture preference. | |
106 | Architectures providing fast unaligned write byte-packed basic types to save | |
5ba9f198 | 107 | space, aligning each type on byte boundaries (8-bit). Architectures with slow |
3bf79539 | 108 | unaligned writes align types on specific alignment values. If no specific |
370eae99 MD |
109 | alignment is declared for a type, it is assumed to be bit-packed for |
110 | integers with size not multiple of 8 bits and for gcc bitfields. All | |
111 | other types are byte-packed. | |
5ba9f198 | 112 | |
3bf79539 | 113 | Metadata attribute representation of a specific alignment: |
5ba9f198 MD |
114 | |
115 | align = value; /* value in bits */ | |
116 | ||
117 | 4.1.3 Byte order | |
118 | ||
3bf79539 MD |
119 | By default, the native endianness of the source architecture the trace is used. |
120 | Byte order can be overridden for a basic type by specifying a "byte_order" | |
121 | attribute. Typical use-case is to specify the network byte order (big endian: | |
122 | "be") to save data captured from the network into the trace without conversion. | |
123 | If not specified, the byte order is native. | |
5ba9f198 MD |
124 | |
125 | Metadata representation: | |
126 | ||
127 | byte_order = native OR network OR be OR le; /* network and be are aliases */ | |
128 | ||
129 | 4.1.4 Size | |
130 | ||
131 | Type size, in bits, for integers and floats is that returned by "sizeof()" in C | |
132 | multiplied by CHAR_BIT. | |
133 | We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed | |
134 | to 8 bits for cross-endianness compatibility. | |
135 | ||
136 | Metadata representation: | |
137 | ||
138 | size = value; (value is in bits) | |
139 | ||
140 | 4.1.5 Integers | |
141 | ||
142 | Signed integers are represented in two-complement. Integer alignment, size, | |
143 | signedness and byte ordering are defined in the metadata. Integers aligned on | |
144 | byte size (8-bit) and with length multiple of byte size (8-bit) correspond to | |
145 | the C99 standard integers. In addition, integers with alignment and/or size that | |
146 | are _not_ a multiple of the byte size are permitted; these correspond to the C99 | |
147 | standard bitfields, with the added specification that the CTF integer bitfields | |
148 | have a fixed binary representation. A MIT-licensed reference implementation of | |
149 | the CTF portable bitfields is available at: | |
150 | ||
151 | http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h | |
152 | ||
153 | Binary representation of integers: | |
154 | ||
155 | - On little and big endian: | |
156 | - Within a byte, high bits correspond to an integer high bits, and low bits | |
157 | correspond to low bits. | |
158 | - On little endian: | |
159 | - Integer across multiple bytes are placed from the less significant to the | |
160 | most significant. | |
161 | - Consecutive integers are placed from lower bits to higher bits (even within | |
162 | a byte). | |
163 | - On big endian: | |
164 | - Integer across multiple bytes are placed from the most significant to the | |
165 | less significant. | |
166 | - Consecutive integers are placed from higher bits to lower bits (even within | |
167 | a byte). | |
168 | ||
169 | This binary representation is derived from the bitfield implementation in GCC | |
170 | for little and big endian. However, contrary to what GCC does, integers can | |
171 | cross units boundaries (no padding is required). Padding can be explicitely | |
172 | added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed. | |
173 | ||
174 | Metadata representation: | |
175 | ||
80fd2569 | 176 | integer { |
5ba9f198 MD |
177 | signed = true OR false; /* default false */ |
178 | byte_order = native OR network OR be OR le; /* default native */ | |
179 | size = value; /* value in bits, no default */ | |
180 | align = value; /* value in bits */ | |
2152348f | 181 | } |
5ba9f198 | 182 | |
80fd2569 | 183 | Example of type inheritance (creation of a uint32_t named type): |
5ba9f198 | 184 | |
359894ac | 185 | typealias integer { |
9e4e34e9 | 186 | size = 32; |
5ba9f198 MD |
187 | signed = false; |
188 | align = 32; | |
38b8da21 | 189 | } := uint32_t; |
5ba9f198 | 190 | |
80fd2569 | 191 | Definition of a named 5-bit signed bitfield: |
5ba9f198 | 192 | |
359894ac | 193 | typealias integer { |
5ba9f198 MD |
194 | size = 5; |
195 | signed = true; | |
196 | align = 1; | |
38b8da21 | 197 | } := int5_t; |
5ba9f198 MD |
198 | |
199 | 4.1.6 GNU/C bitfields | |
200 | ||
201 | The GNU/C bitfields follow closely the integer representation, with a | |
202 | particularity on alignment: if a bitfield cannot fit in the current unit, the | |
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203 | unit is padded and the bitfield starts at the following unit. The unit size is |
204 | defined by the size of the type "unit_type". | |
5ba9f198 | 205 | |
2152348f | 206 | Metadata representation: |
80fd2569 MD |
207 | |
208 | unit_type name:size: | |
209 | ||
5ba9f198 MD |
210 | As an example, the following structure declared in C compiled by GCC: |
211 | ||
212 | struct example { | |
213 | short a:12; | |
214 | short b:5; | |
215 | }; | |
216 | ||
2152348f MD |
217 | The example structure is aligned on the largest element (short). The second |
218 | bitfield would be aligned on the next unit boundary, because it would not fit in | |
219 | the current unit. | |
5ba9f198 MD |
220 | |
221 | 4.1.7 Floating point | |
222 | ||
223 | The floating point values byte ordering is defined in the metadata. | |
224 | ||
225 | Floating point values follow the IEEE 754-2008 standard interchange formats. | |
226 | Description of the floating point values include the exponent and mantissa size | |
227 | in bits. Some requirements are imposed on the floating point values: | |
228 | ||
229 | - FLT_RADIX must be 2. | |
230 | - mant_dig is the number of digits represented in the mantissa. It is specified | |
231 | by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and | |
232 | LDBL_MANT_DIG as defined by <float.h>. | |
233 | - exp_dig is the number of digits represented in the exponent. Given that | |
234 | mant_dig is one bit more than its actual size in bits (leading 1 is not | |
235 | needed) and also given that the sign bit always takes one bit, exp_dig can be | |
236 | specified as: | |
237 | ||
238 | - sizeof(float) * CHAR_BIT - FLT_MANT_DIG | |
239 | - sizeof(double) * CHAR_BIT - DBL_MANT_DIG | |
240 | - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG | |
241 | ||
242 | Metadata representation: | |
243 | ||
80fd2569 | 244 | floating_point { |
5ba9f198 MD |
245 | exp_dig = value; |
246 | mant_dig = value; | |
247 | byte_order = native OR network OR be OR le; | |
2152348f | 248 | } |
5ba9f198 MD |
249 | |
250 | Example of type inheritance: | |
251 | ||
359894ac | 252 | typealias floating_point { |
5ba9f198 MD |
253 | exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */ |
254 | mant_dig = 24; /* FLT_MANT_DIG */ | |
255 | byte_order = native; | |
38b8da21 | 256 | } := float; |
5ba9f198 MD |
257 | |
258 | TODO: define NaN, +inf, -inf behavior. | |
259 | ||
260 | 4.1.8 Enumerations | |
261 | ||
262 | Enumerations are a mapping between an integer type and a table of strings. The | |
263 | numerical representation of the enumeration follows the integer type specified | |
264 | by the metadata. The enumeration mapping table is detailed in the enumeration | |
3bf79539 MD |
265 | description within the metadata. The mapping table maps inclusive value ranges |
266 | (or single values) to strings. Instead of being limited to simple | |
267 | "value -> string" mappings, these enumerations map | |
80fd2569 | 268 | "[ start_value ... end_value ] -> string", which map inclusive ranges of |
3bf79539 MD |
269 | values to strings. An enumeration from the C language can be represented in |
270 | this format by having the same start_value and end_value for each element, which | |
271 | is in fact a range of size 1. This single-value range is supported without | |
4767a9e7 | 272 | repeating the start and end values with the value = string declaration. |
80fd2569 | 273 | |
a9b83695 | 274 | enum name : integer_type { |
359894ac | 275 | somestring = start_value1 ... end_value1, |
80fd2569 MD |
276 | "other string" = start_value2 ... end_value2, |
277 | yet_another_string, /* will be assigned to end_value2 + 1 */ | |
278 | "some other string" = value, | |
279 | ... | |
280 | }; | |
281 | ||
282 | If the values are omitted, the enumeration starts at 0 and increment of 1 for | |
283 | each entry: | |
284 | ||
a9b83695 | 285 | enum name : unsigned int { |
80fd2569 MD |
286 | ZERO, |
287 | ONE, | |
288 | TWO, | |
289 | TEN = 10, | |
290 | ELEVEN, | |
3bf79539 | 291 | }; |
5ba9f198 | 292 | |
80fd2569 | 293 | Overlapping ranges within a single enumeration are implementation defined. |
5ba9f198 | 294 | |
2152348f MD |
295 | A nameless enumeration can be declared as a field type or as part of a typedef: |
296 | ||
a9b83695 | 297 | enum : integer_type { |
2152348f MD |
298 | ... |
299 | } | |
300 | ||
1fad7a85 | 301 | |
5ba9f198 MD |
302 | 4.2 Compound types |
303 | ||
1fad7a85 MD |
304 | Compound are aggregation of type declarations. Compound types include |
305 | structures, variant, arrays, sequences, and strings. | |
306 | ||
5ba9f198 MD |
307 | 4.2.1 Structures |
308 | ||
309 | Structures are aligned on the largest alignment required by basic types | |
310 | contained within the structure. (This follows the ISO/C standard for structures) | |
311 | ||
80fd2569 | 312 | Metadata representation of a named structure: |
5ba9f198 | 313 | |
80fd2569 MD |
314 | struct name { |
315 | field_type field_name; | |
316 | field_type field_name; | |
317 | ... | |
318 | }; | |
5ba9f198 MD |
319 | |
320 | Example: | |
321 | ||
80fd2569 MD |
322 | struct example { |
323 | integer { /* Nameless type */ | |
324 | size = 16; | |
325 | signed = true; | |
326 | align = 16; | |
327 | } first_field_name; | |
328 | uint64_t second_field_name; /* Named type declared in the metadata */ | |
3bf79539 | 329 | }; |
5ba9f198 MD |
330 | |
331 | The fields are placed in a sequence next to each other. They each possess a | |
332 | field name, which is a unique identifier within the structure. | |
333 | ||
2152348f | 334 | A nameless structure can be declared as a field type or as part of a typedef: |
80fd2569 MD |
335 | |
336 | struct { | |
337 | ... | |
2152348f | 338 | } |
80fd2569 | 339 | |
77a98c82 | 340 | 4.2.2 Variants (Discriminated/Tagged Unions) |
fcba70d4 | 341 | |
fdf2bb05 MD |
342 | A CTF variant is a selection between different types. A CTF variant must |
343 | always be defined within the scope of a structure or within fields | |
344 | contained within a structure (defined recursively). A "tag" enumeration | |
345 | field must appear in either the same lexical scope, prior to the variant | |
346 | field (in field declaration order), in an uppermost lexical scope (see | |
347 | Section 7.2.1), or in an uppermost dynamic scope (see Section 7.2.2). | |
348 | The type selection is indicated by the mapping from the enumeration | |
349 | value to the string used as variant type selector. The field to use as | |
350 | tag is specified by the "tag_field", specified between "< >" after the | |
351 | "variant" keyword for unnamed variants, and after "variant name" for | |
352 | named variants. | |
fcba70d4 MD |
353 | |
354 | The alignment of the variant is the alignment of the type as selected by the tag | |
355 | value for the specific instance of the variant. The alignment of the type | |
356 | containing the variant is independent of the variant alignment. The size of the | |
357 | variant is the size as selected by the tag value for the specific instance of | |
358 | the variant. | |
359 | ||
360 | A named variant declaration followed by its definition within a structure | |
361 | declaration: | |
362 | ||
363 | variant name { | |
364 | field_type sel1; | |
365 | field_type sel2; | |
366 | field_type sel3; | |
367 | ... | |
368 | }; | |
369 | ||
370 | struct { | |
a9b83695 | 371 | enum : integer_type { sel1, sel2, sel3, ... } tag_field; |
fcba70d4 MD |
372 | ... |
373 | variant name <tag_field> v; | |
374 | } | |
375 | ||
376 | An unnamed variant definition within a structure is expressed by the following | |
377 | metadata: | |
378 | ||
379 | struct { | |
a9b83695 | 380 | enum : integer_type { sel1, sel2, sel3, ... } tag_field; |
fcba70d4 MD |
381 | ... |
382 | variant <tag_field> { | |
383 | field_type sel1; | |
384 | field_type sel2; | |
385 | field_type sel3; | |
386 | ... | |
387 | } v; | |
388 | } | |
389 | ||
390 | Example of a named variant within a sequence that refers to a single tag field: | |
391 | ||
392 | variant example { | |
393 | uint32_t a; | |
394 | uint64_t b; | |
395 | short c; | |
396 | }; | |
397 | ||
398 | struct { | |
a9b83695 | 399 | enum : uint2_t { a, b, c } choice; |
15850440 | 400 | variant example <choice> v[unsigned int]; |
fcba70d4 MD |
401 | } |
402 | ||
403 | Example of an unnamed variant: | |
404 | ||
405 | struct { | |
a9b83695 | 406 | enum : uint2_t { a, b, c, d } choice; |
fcba70d4 MD |
407 | /* Unrelated fields can be added between the variant and its tag */ |
408 | int32_t somevalue; | |
409 | variant <choice> { | |
410 | uint32_t a; | |
411 | uint64_t b; | |
412 | short c; | |
413 | struct { | |
414 | unsigned int field1; | |
415 | uint64_t field2; | |
416 | } d; | |
417 | } s; | |
418 | } | |
419 | ||
420 | Example of an unnamed variant within an array: | |
421 | ||
422 | struct { | |
a9b83695 | 423 | enum : uint2_t { a, b, c } choice; |
fcba70d4 MD |
424 | variant <choice> { |
425 | uint32_t a; | |
426 | uint64_t b; | |
427 | short c; | |
15850440 | 428 | } v[10]; |
fcba70d4 MD |
429 | } |
430 | ||
431 | Example of a variant type definition within a structure, where the defined type | |
432 | is then declared within an array of structures. This variant refers to a tag | |
433 | located in an upper lexical scope. This example clearly shows that a variant | |
434 | type definition referring to the tag "x" uses the closest preceding field from | |
435 | the lexical scope of the type definition. | |
436 | ||
437 | struct { | |
a9b83695 | 438 | enum : uint2_t { a, b, c, d } x; |
fcba70d4 MD |
439 | |
440 | typedef variant <x> { /* | |
441 | * "x" refers to the preceding "x" enumeration in the | |
442 | * lexical scope of the type definition. | |
443 | */ | |
444 | uint32_t a; | |
445 | uint64_t b; | |
446 | short c; | |
447 | } example_variant; | |
448 | ||
449 | struct { | |
a9b83695 | 450 | enum : int { x, y, z } x; /* This enumeration is not used by "v". */ |
fcba70d4 | 451 | example_variant v; /* |
a9b83695 | 452 | * "v" uses the "enum : uint2_t { a, b, c, d }" |
fcba70d4 MD |
453 | * tag. |
454 | */ | |
455 | } a[10]; | |
456 | } | |
457 | ||
458 | 4.2.3 Arrays | |
5ba9f198 MD |
459 | |
460 | Arrays are fixed-length. Their length is declared in the type declaration within | |
461 | the metadata. They contain an array of "inner type" elements, which can refer to | |
462 | any type not containing the type of the array being declared (no circular | |
3bf79539 | 463 | dependency). The length is the number of elements in an array. |
5ba9f198 | 464 | |
2152348f | 465 | Metadata representation of a named array: |
80fd2569 MD |
466 | |
467 | typedef elem_type name[length]; | |
5ba9f198 | 468 | |
2152348f | 469 | A nameless array can be declared as a field type within a structure, e.g.: |
5ba9f198 | 470 | |
2152348f | 471 | uint8_t field_name[10]; |
80fd2569 | 472 | |
5ba9f198 | 473 | |
fcba70d4 | 474 | 4.2.4 Sequences |
5ba9f198 MD |
475 | |
476 | Sequences are dynamically-sized arrays. They start with an integer that specify | |
477 | the length of the sequence, followed by an array of "inner type" elements. | |
3bf79539 | 478 | The length is the number of elements in the sequence. |
5ba9f198 | 479 | |
2152348f | 480 | Metadata representation for a named sequence: |
80fd2569 MD |
481 | |
482 | typedef elem_type name[length_type]; | |
483 | ||
484 | A nameless sequence can be declared as a field type, e.g.: | |
485 | ||
80fd2569 MD |
486 | long field_name[int]; |
487 | ||
488 | The length type follows the integer types specifications, and the sequence | |
5ba9f198 MD |
489 | elements follow the "array" specifications. |
490 | ||
fcba70d4 | 491 | 4.2.5 Strings |
5ba9f198 MD |
492 | |
493 | Strings are an array of bytes of variable size and are terminated by a '\0' | |
494 | "NULL" character. Their encoding is described in the metadata. In absence of | |
495 | encoding attribute information, the default encoding is UTF-8. | |
496 | ||
80fd2569 MD |
497 | Metadata representation of a named string type: |
498 | ||
359894ac | 499 | typealias string { |
5ba9f198 | 500 | encoding = UTF8 OR ASCII; |
38b8da21 | 501 | } := name; |
5ba9f198 | 502 | |
80fd2569 MD |
503 | A nameless string type can be declared as a field type: |
504 | ||
505 | string field_name; /* Use default UTF8 encoding */ | |
5ba9f198 | 506 | |
3bf79539 MD |
507 | 5. Event Packet Header |
508 | ||
509 | The event packet header consists of two part: one is mandatory and have a fixed | |
510 | layout. The second part, the "event packet context", has its layout described in | |
511 | the metadata. | |
5ba9f198 | 512 | |
3bf79539 MD |
513 | - Aligned on page size. Fixed size. Fields either aligned or packed (depending |
514 | on the architecture preference). | |
515 | No padding at the end of the event packet header. Native architecture byte | |
5ba9f198 | 516 | ordering. |
3bf79539 MD |
517 | |
518 | Fixed layout (event packet header): | |
519 | ||
5ba9f198 MD |
520 | - Magic number (CTF magic numbers: 0xC1FC1FC1 and its reverse endianness |
521 | representation: 0xC11FFCC1) It needs to have a non-symmetric bytewise | |
522 | representation. Used to distinguish between big and little endian traces (this | |
523 | information is determined by knowing the endianness of the architecture | |
524 | reading the trace and comparing the magic number against its value and the | |
525 | reverse, 0xC11FFCC1). This magic number specifies that we use the CTF metadata | |
526 | description language described in this document. Different magic numbers | |
527 | should be used for other metadata description languages. | |
3bf79539 | 528 | - Trace UUID, used to ensure the event packet match the metadata used. |
5ba9f198 MD |
529 | (note: we cannot use a metadata checksum because metadata can be appended to |
530 | while tracing is active) | |
3bf79539 MD |
531 | - Stream ID, used as reference to stream description in metadata. |
532 | ||
533 | Metadata-defined layout (event packet context): | |
534 | ||
535 | - Event packet content size (in bytes). | |
536 | - Event packet size (in bytes, includes padding). | |
537 | - Event packet content checksum (optional). Checksum excludes the event packet | |
538 | header. | |
539 | - Per-stream event packet sequence count (to deal with UDP packet loss). The | |
540 | number of significant sequence counter bits should also be present, so | |
541 | wrap-arounds are deal with correctly. | |
542 | - Timestamp at the beginning and timestamp at the end of the event packet. | |
543 | Both timestamps are written in the packet header, but sampled respectively | |
544 | while (or before) writing the first event and while (or after) writing the | |
545 | last event in the packet. The inclusive range between these timestamps should | |
546 | include all event timestamps assigned to events contained within the packet. | |
5ba9f198 | 547 | - Events discarded count |
3bf79539 MD |
548 | - Snapshot of a per-stream free-running counter, counting the number of |
549 | events discarded that were supposed to be written in the stream prior to | |
550 | the first event in the event packet. | |
5ba9f198 | 551 | * Note: producer-consumer buffer full condition should fill the current |
3bf79539 | 552 | event packet with padding so we know exactly where events have been |
5ba9f198 | 553 | discarded. |
3bf79539 MD |
554 | - Lossless compression scheme used for the event packet content. Applied |
555 | directly to raw data. New types of compression can be added in following | |
556 | versions of the format. | |
5ba9f198 MD |
557 | 0: no compression scheme |
558 | 1: bzip2 | |
559 | 2: gzip | |
3bf79539 MD |
560 | 3: xz |
561 | - Cypher used for the event packet content. Applied after compression. | |
5ba9f198 MD |
562 | 0: no encryption |
563 | 1: AES | |
3bf79539 | 564 | - Checksum scheme used for the event packet content. Applied after encryption. |
5ba9f198 MD |
565 | 0: no checksum |
566 | 1: md5 | |
567 | 2: sha1 | |
568 | 3: crc32 | |
569 | ||
3bf79539 MD |
570 | 5.1 Event Packet Header Fixed Layout Description |
571 | ||
80fd2569 MD |
572 | struct event_packet_header { |
573 | uint32_t magic; | |
574 | uint8_t trace_uuid[16]; | |
3bf79539 | 575 | uint32_t stream_id; |
80fd2569 | 576 | }; |
5ba9f198 | 577 | |
3bf79539 MD |
578 | 5.2 Event Packet Context Description |
579 | ||
580 | Event packet context example. These are declared within the stream declaration | |
581 | in the metadata. All these fields are optional except for "content_size" and | |
582 | "packet_size", which must be present in the context. | |
583 | ||
584 | An example event packet context type: | |
585 | ||
80fd2569 | 586 | struct event_packet_context { |
3bf79539 MD |
587 | uint64_t timestamp_begin; |
588 | uint64_t timestamp_end; | |
589 | uint32_t checksum; | |
590 | uint32_t stream_packet_count; | |
591 | uint32_t events_discarded; | |
592 | uint32_t cpu_id; | |
593 | uint32_t/uint16_t content_size; | |
594 | uint32_t/uint16_t packet_size; | |
595 | uint8_t stream_packet_count_bits; /* Significant counter bits */ | |
596 | uint8_t compression_scheme; | |
597 | uint8_t encryption_scheme; | |
3b0f8e4d | 598 | uint8_t checksum_scheme; |
3bf79539 | 599 | }; |
5ba9f198 | 600 | |
fcba70d4 | 601 | |
5ba9f198 MD |
602 | 6. Event Structure |
603 | ||
604 | The overall structure of an event is: | |
605 | ||
fcba70d4 | 606 | 1 - Stream Packet Context (as specified by the stream metadata) |
fdf2bb05 MD |
607 | 2 - Event Header (as specified by the stream metadata) |
608 | 3 - Stream Event Context (as specified by the stream metadata) | |
609 | 4 - Event Context (as specified by the event metadata) | |
610 | 5 - Event Payload (as specified by the event metadata) | |
5ba9f198 | 611 | |
fdf2bb05 | 612 | This structure defines an implicit dynamic scoping, where variants |
7d9d7e92 MD |
613 | located in inner structures (those with a higher number in the listing |
614 | above) can refer to the fields of outer structures (with lower number in | |
615 | the listing above). See Section 7.2 Metadata Scopes for more detail. | |
5ba9f198 | 616 | |
fdf2bb05 | 617 | 6.1 Event Header |
fcba70d4 MD |
618 | |
619 | Event headers can be described within the metadata. We hereby propose, as an | |
620 | example, two types of events headers. Type 1 accommodates streams with less than | |
621 | 31 event IDs. Type 2 accommodates streams with 31 or more event IDs. | |
5ba9f198 | 622 | |
3bf79539 MD |
623 | One major factor can vary between streams: the number of event IDs assigned to |
624 | a stream. Luckily, this information tends to stay relatively constant (modulo | |
5ba9f198 | 625 | event registration while trace is being recorded), so we can specify different |
3bf79539 | 626 | representations for streams containing few event IDs and streams containing |
5ba9f198 MD |
627 | many event IDs, so we end up representing the event ID and timestamp as densely |
628 | as possible in each case. | |
629 | ||
fcba70d4 MD |
630 | The header is extended in the rare occasions where the information cannot be |
631 | represented in the ranges available in the standard event header. They are also | |
3bf79539 MD |
632 | used in the rare occasions where the data required for a field could not be |
633 | collected: the flag corresponding to the missing field within the missing_fields | |
634 | array is then set to 1. | |
5ba9f198 MD |
635 | |
636 | Types uintX_t represent an X-bit unsigned integer. | |
637 | ||
638 | ||
fdf2bb05 | 639 | 6.1.1 Type 1 - Few event IDs |
5ba9f198 MD |
640 | |
641 | - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture | |
642 | preference). | |
5ba9f198 | 643 | - Native architecture byte ordering. |
fcba70d4 MD |
644 | - For "compact" selection |
645 | - Fixed size: 32 bits. | |
646 | - For "extended" selection | |
647 | - Size depends on the architecture and variant alignment. | |
5ba9f198 | 648 | |
80fd2569 | 649 | struct event_header_1 { |
fcba70d4 MD |
650 | /* |
651 | * id: range: 0 - 30. | |
652 | * id 31 is reserved to indicate an extended header. | |
653 | */ | |
a9b83695 | 654 | enum : uint5_t { compact = 0 ... 30, extended = 31 } id; |
fcba70d4 MD |
655 | variant <id> { |
656 | struct { | |
657 | uint27_t timestamp; | |
658 | } compact; | |
659 | struct { | |
660 | uint32_t id; /* 32-bit event IDs */ | |
661 | uint64_t timestamp; /* 64-bit timestamps */ | |
662 | } extended; | |
663 | } v; | |
5ba9f198 MD |
664 | }; |
665 | ||
5ba9f198 | 666 | |
fdf2bb05 | 667 | 6.1.2 Type 2 - Many event IDs |
5ba9f198 | 668 | |
fcba70d4 | 669 | - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture |
5ba9f198 | 670 | preference). |
5ba9f198 | 671 | - Native architecture byte ordering. |
fcba70d4 MD |
672 | - For "compact" selection |
673 | - Size depends on the architecture and variant alignment. | |
674 | - For "extended" selection | |
675 | - Size depends on the architecture and variant alignment. | |
5ba9f198 | 676 | |
80fd2569 | 677 | struct event_header_2 { |
fcba70d4 MD |
678 | /* |
679 | * id: range: 0 - 65534. | |
680 | * id 65535 is reserved to indicate an extended header. | |
681 | */ | |
a9b83695 | 682 | enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id; |
fcba70d4 MD |
683 | variant <id> { |
684 | struct { | |
685 | uint32_t timestamp; | |
686 | } compact; | |
687 | struct { | |
688 | uint32_t id; /* 32-bit event IDs */ | |
689 | uint64_t timestamp; /* 64-bit timestamps */ | |
690 | } extended; | |
691 | } v; | |
5ba9f198 MD |
692 | }; |
693 | ||
5ba9f198 MD |
694 | |
695 | 6.2 Event Context | |
696 | ||
697 | The event context contains information relative to the current event. The choice | |
fcba70d4 MD |
698 | and meaning of this information is specified by the metadata "stream" and |
699 | "event" information. The "stream" context is applied to all events within the | |
700 | stream. The "stream" context structure follows the event header. The "event" | |
701 | context is applied to specific events. Its structure follows the "stream" | |
702 | context stucture. | |
5ba9f198 | 703 | |
fcba70d4 MD |
704 | An example of stream-level event context is to save the event payload size with |
705 | each event, or to save the current PID with each event. These are declared | |
706 | within the stream declaration within the metadata: | |
5ba9f198 | 707 | |
fcba70d4 MD |
708 | stream { |
709 | ... | |
710 | event { | |
711 | ... | |
4fa992a5 | 712 | context := struct { |
80fd2569 MD |
713 | uint pid; |
714 | uint16_t payload_size; | |
3bf79539 | 715 | }; |
fcba70d4 MD |
716 | } |
717 | }; | |
718 | ||
719 | An example of event-specific event context is to declare a bitmap of missing | |
720 | fields, only appended after the stream event context if the extended event | |
721 | header is selected. NR_FIELDS is the number of fields within the event (a | |
722 | numeric value). | |
5ba9f198 | 723 | |
fcba70d4 MD |
724 | event { |
725 | context = struct { | |
726 | variant <id> { | |
727 | struct { } compact; | |
728 | struct { | |
729 | uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */ | |
730 | } extended; | |
731 | } v; | |
732 | }; | |
733 | ... | |
734 | } | |
5ba9f198 MD |
735 | |
736 | 6.3 Event Payload | |
737 | ||
738 | An event payload contains fields specific to a given event type. The fields | |
739 | belonging to an event type are described in the event-specific metadata | |
740 | within a structure type. | |
741 | ||
742 | 6.3.1 Padding | |
743 | ||
744 | No padding at the end of the event payload. This differs from the ISO/C standard | |
745 | for structures, but follows the CTF standard for structures. In a trace, even | |
746 | though it makes sense to align the beginning of a structure, it really makes no | |
747 | sense to add padding at the end of the structure, because structures are usually | |
748 | not followed by a structure of the same type. | |
749 | ||
750 | This trick can be done by adding a zero-length "end" field at the end of the C | |
751 | structures, and by using the offset of this field rather than using sizeof() | |
3bf79539 | 752 | when calculating the size of a structure (see Appendix "A. Helper macros"). |
5ba9f198 MD |
753 | |
754 | 6.3.2 Alignment | |
755 | ||
756 | The event payload is aligned on the largest alignment required by types | |
757 | contained within the payload. (This follows the ISO/C standard for structures) | |
758 | ||
759 | ||
5ba9f198 MD |
760 | 7. Metadata |
761 | ||
4fafe1ad MD |
762 | The meta-data is located in a stream identified by its name: "metadata". |
763 | It is made of "event packets", which each start with an event packet | |
764 | header. The event type within the metadata stream have no event header | |
765 | nor event context. Each event only contains a null-terminated "string" | |
766 | payload, which is a metadata description entry. The events are packed | |
767 | one next to another. Each event packet start with an event packet | |
768 | header, which contains, amongst other fields, the magic number and trace | |
769 | UUID. In the event packet header, the trace UUID is represented as an | |
770 | array of bytes. Within the string-based metadata description, the trace | |
771 | UUID is represented as a string of hexadecimal digits and dashes "-". | |
772 | ||
773 | The metadata can be parsed by reading through the metadata strings, | |
774 | skipping null-characters. Type names are made of a single identifier, | |
775 | and can be surrounded by prefix/postfix. Text contained within "/*" and | |
776 | "*/", as well as within "//" and end of line, are treated as comments. | |
777 | Boolean values can be represented as true, TRUE, or 1 for true, and | |
778 | false, FALSE, or 0 for false. | |
fcba70d4 | 779 | |
fdf2bb05 MD |
780 | |
781 | 7.1 Declaration vs Definition | |
782 | ||
783 | A declaration associates a layout to a type, without specifying where | |
784 | this type is located in the event structure hierarchy (see Section 6). | |
785 | This therefore includes typedef, typealias, as well as all type | |
786 | specifiers. In certain circumstances (typedef, structure field and | |
787 | variant field), a declaration is followed by a declarator, which specify | |
788 | the newly defined type name (for typedef), or the field name (for | |
789 | declarations located within structure and variants). Array and sequence, | |
790 | declared with square brackets ("[" "]"), are part of the declarator, | |
a9b83695 MD |
791 | similarly to C99. The enumeration base type is specified by |
792 | ": base_type", which is part of the type specifier. The variant tag | |
793 | name, specified between "<" ">", is also part of the type specifier. | |
fdf2bb05 MD |
794 | |
795 | A definition associates a type to a location in the event structure | |
b9606a77 MD |
796 | hierarchy (see Section 6). This association is denoted by ":=", as shown |
797 | in Section 7.3. | |
fdf2bb05 MD |
798 | |
799 | ||
800 | 7.2 Metadata Scopes | |
801 | ||
802 | CTF metadata uses two different types of scoping: a lexical scope is | |
803 | used for declarations and type definitions, and a dynamic scope is used | |
804 | for variants references to tag fields. | |
805 | ||
806 | 7.2.1 Lexical Scope | |
807 | ||
d285084f MD |
808 | Each of "trace", "stream", "event", "struct" and "variant" have their own |
809 | nestable declaration scope, within which types can be declared using "typedef" | |
fdf2bb05 | 810 | and "typealias". A root declaration scope also contains all declarations |
7d9d7e92 | 811 | located outside of any of the aforementioned declarations. An inner |
fdf2bb05 | 812 | declaration scope can refer to type declared within its container |
7d9d7e92 MD |
813 | lexical scope prior to the inner declaration scope. Redefinition of a |
814 | typedef or typealias is not valid, although hiding an upper scope | |
fdf2bb05 MD |
815 | typedef or typealias is allowed within a sub-scope. |
816 | ||
817 | 7.2.2 Dynamic Scope | |
818 | ||
7d9d7e92 MD |
819 | A dynamic scope consists in the lexical scope augmented with the |
820 | implicit event structure definition hierarchy presented at Section 6. | |
821 | The dynamic scope is only used for variant tag definitions. It is used | |
822 | at definition time to look up the location of the tag field associated | |
823 | with a variant. | |
824 | ||
825 | Therefore, variants in lower levels in the dynamic scope (e.g. event | |
826 | context) can refer to a tag field located in upper levels (e.g. in the | |
827 | event header) by specifying, in this case, the associated tag with | |
828 | <header.field_name>. This allows, for instance, the event context to | |
829 | define a variant referring to the "id" field of the event header as | |
830 | selector. | |
fdf2bb05 MD |
831 | |
832 | The target dynamic scope must be specified explicitly when referring to | |
833 | a field outside of the local static scope. The dynamic scope prefixes | |
834 | are thus: | |
835 | ||
7d9d7e92 MD |
836 | - Stream Packet Context: <stream.packet.context. >, |
837 | - Event Header: <stream.event.header. >, | |
838 | - Stream Event Context: <stream.event.context. >, | |
839 | - Event Context: <event.context. >, | |
840 | - Event Payload: <event.fields. >. | |
fdf2bb05 MD |
841 | |
842 | Multiple declarations of the same field name within a single scope is | |
843 | not valid. It is however valid to re-use the same field name in | |
844 | different scopes. There is no possible conflict, because the dynamic | |
845 | scope must be specified when a variant refers to a tag field located in | |
846 | a different dynamic scope. | |
847 | ||
457d8b0a MD |
848 | The information available in the dynamic scopes can be thought of as the |
849 | current tracing context. At trace production, information about the | |
850 | current context is saved into the specified scope field levels. At trace | |
851 | consumption, for each event, the current trace context is therefore | |
852 | readable by accessing the upper dynamic scopes. | |
853 | ||
fdf2bb05 | 854 | |
b9606a77 | 855 | 7.3 Metadata Examples |
d285084f | 856 | |
fcba70d4 | 857 | The grammar representing the CTF metadata is presented in |
fdf2bb05 MD |
858 | Appendix C. CTF Metadata Grammar. This section presents a rather ligher |
859 | reading that consists in examples of CTF metadata, with template values: | |
5ba9f198 MD |
860 | |
861 | trace { | |
fdf2bb05 | 862 | major = value; /* Trace format version */ |
5ba9f198 | 863 | minor = value; |
fdf2bb05 | 864 | uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */ |
3bf79539 MD |
865 | word_size = value; |
866 | }; | |
5ba9f198 | 867 | |
3bf79539 MD |
868 | stream { |
869 | id = stream_id; | |
fdf2bb05 | 870 | /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */ |
4fa992a5 MD |
871 | event.header := event_header_1 OR event_header_2; |
872 | event.context := struct { | |
77a98c82 | 873 | ... |
3bf79539 | 874 | }; |
4fa992a5 | 875 | packet.context := struct { |
77a98c82 | 876 | ... |
3bf79539 MD |
877 | }; |
878 | }; | |
5ba9f198 MD |
879 | |
880 | event { | |
3d13ef1a | 881 | name = event_name; |
3bf79539 MD |
882 | id = value; /* Numeric identifier within the stream */ |
883 | stream = stream_id; | |
4fa992a5 | 884 | context := struct { |
fcba70d4 MD |
885 | ... |
886 | }; | |
4fa992a5 | 887 | fields := struct { |
80fd2569 MD |
888 | ... |
889 | }; | |
3bf79539 | 890 | }; |
5ba9f198 MD |
891 | |
892 | /* More detail on types in section 4. Types */ | |
893 | ||
3d13ef1a MD |
894 | /* |
895 | * Named types: | |
896 | * | |
4fa992a5 | 897 | * Type declarations behave similarly to the C standard. |
3d13ef1a MD |
898 | */ |
899 | ||
80af8ac6 | 900 | typedef aliased_type_specifiers new_type_declarators; |
2152348f | 901 | |
3d13ef1a | 902 | /* e.g.: typedef struct example new_type_name[10]; */ |
80fd2569 | 903 | |
4fa992a5 MD |
904 | /* |
905 | * typealias | |
906 | * | |
907 | * The "typealias" declaration can be used to give a name (including | |
80af8ac6 MD |
908 | * pointer declarator specifier) to a type. It should also be used to |
909 | * map basic C types (float, int, unsigned long, ...) to a CTF type. | |
910 | * Typealias is a superset of "typedef": it also allows assignment of a | |
38b8da21 | 911 | * simple variable identifier to a type. |
4fa992a5 MD |
912 | */ |
913 | ||
914 | typealias type_class { | |
80fd2569 | 915 | ... |
38b8da21 | 916 | } := type_specifiers type_declarator; |
2152348f | 917 | |
3d13ef1a MD |
918 | /* |
919 | * e.g.: | |
4fa992a5 | 920 | * typealias integer { |
3d13ef1a MD |
921 | * size = 32; |
922 | * align = 32; | |
923 | * signed = false; | |
38b8da21 | 924 | * } := struct page *; |
359894ac MD |
925 | * |
926 | * typealias integer { | |
927 | * size = 32; | |
928 | * align = 32; | |
929 | * signed = true; | |
38b8da21 | 930 | * } := int; |
3d13ef1a | 931 | */ |
80fd2569 MD |
932 | |
933 | struct name { | |
3bf79539 MD |
934 | ... |
935 | }; | |
5ba9f198 | 936 | |
fcba70d4 MD |
937 | variant name { |
938 | ... | |
939 | }; | |
940 | ||
a9b83695 | 941 | enum name : integer_type { |
3bf79539 MD |
942 | ... |
943 | }; | |
944 | ||
2152348f | 945 | |
4fa992a5 MD |
946 | /* |
947 | * Unnamed types, contained within compound type fields, typedef or typealias. | |
948 | */ | |
2152348f | 949 | |
80fd2569 MD |
950 | struct { |
951 | ... | |
2152348f | 952 | } |
5ba9f198 | 953 | |
fcba70d4 MD |
954 | variant { |
955 | ... | |
956 | } | |
957 | ||
a9b83695 | 958 | enum : integer_type { |
80fd2569 | 959 | ... |
2152348f MD |
960 | } |
961 | ||
962 | typedef type new_type[length]; | |
3bf79539 | 963 | |
2152348f MD |
964 | struct { |
965 | type field_name[length]; | |
966 | } | |
967 | ||
968 | typedef type new_type[length_type]; | |
969 | ||
970 | struct { | |
971 | type field_name[length_type]; | |
972 | } | |
973 | ||
974 | integer { | |
80fd2569 | 975 | ... |
2152348f | 976 | } |
3bf79539 | 977 | |
2152348f | 978 | floating_point { |
80fd2569 | 979 | ... |
2152348f MD |
980 | } |
981 | ||
982 | struct { | |
983 | integer_type field_name:size; /* GNU/C bitfield */ | |
984 | } | |
985 | ||
986 | struct { | |
987 | string field_name; | |
988 | } | |
3bf79539 | 989 | |
fcba70d4 | 990 | |
3bf79539 | 991 | A. Helper macros |
5ba9f198 MD |
992 | |
993 | The two following macros keep track of the size of a GNU/C structure without | |
994 | padding at the end by placing HEADER_END as the last field. A one byte end field | |
995 | is used for C90 compatibility (C99 flexible arrays could be used here). Note | |
996 | that this does not affect the effective structure size, which should always be | |
997 | calculated with the header_sizeof() helper. | |
998 | ||
999 | #define HEADER_END char end_field | |
1000 | #define header_sizeof(type) offsetof(typeof(type), end_field) | |
3bf79539 MD |
1001 | |
1002 | ||
1003 | B. Stream Header Rationale | |
1004 | ||
1005 | An event stream is divided in contiguous event packets of variable size. These | |
1006 | subdivisions allow the trace analyzer to perform a fast binary search by time | |
1007 | within the stream (typically requiring to index only the event packet headers) | |
1008 | without reading the whole stream. These subdivisions have a variable size to | |
1009 | eliminate the need to transfer the event packet padding when partially filled | |
1010 | event packets must be sent when streaming a trace for live viewing/analysis. | |
1011 | An event packet can contain a certain amount of padding at the end. Dividing | |
1012 | streams into event packets is also useful for network streaming over UDP and | |
1013 | flight recorder mode tracing (a whole event packet can be swapped out of the | |
1014 | buffer atomically for reading). | |
1015 | ||
1016 | The stream header is repeated at the beginning of each event packet to allow | |
1017 | flexibility in terms of: | |
1018 | ||
1019 | - streaming support, | |
1020 | - allowing arbitrary buffers to be discarded without making the trace | |
1021 | unreadable, | |
1022 | - allow UDP packet loss handling by either dealing with missing event packet | |
1023 | or asking for re-transmission. | |
1024 | - transparently support flight recorder mode, | |
1025 | - transparently support crash dump. | |
1026 | ||
1027 | The event stream header will therefore be referred to as the "event packet | |
1028 | header" throughout the rest of this document. | |
fcba70d4 MD |
1029 | |
1030 | C. CTF Metadata Grammar | |
1031 | ||
4fa992a5 MD |
1032 | /* |
1033 | * Common Trace Format (CTF) Metadata Grammar. | |
1034 | * | |
1035 | * Inspired from the C99 grammar: | |
1036 | * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A) | |
1037 | * | |
1038 | * Specialized for CTF needs by including only constant and declarations from | |
1039 | * C99 (excluding function declarations), and by adding support for variants, | |
1040 | * sequences and CTF-specific specifiers. | |
1041 | */ | |
1042 | ||
1043 | 1) Lexical grammar | |
1044 | ||
1045 | 1.1) Lexical elements | |
1046 | ||
1047 | token: | |
1048 | keyword | |
1049 | identifier | |
1050 | constant | |
1051 | string-literal | |
1052 | punctuator | |
1053 | ||
1054 | 1.2) Keywords | |
1055 | ||
1056 | keyword: is one of | |
1057 | ||
1058 | const | |
1059 | char | |
1060 | double | |
1061 | enum | |
1062 | event | |
1063 | floating_point | |
1064 | float | |
1065 | integer | |
1066 | int | |
1067 | long | |
1068 | short | |
1069 | signed | |
1070 | stream | |
1071 | string | |
1072 | struct | |
1073 | trace | |
3e1e1a78 | 1074 | typealias |
4fa992a5 MD |
1075 | typedef |
1076 | unsigned | |
1077 | variant | |
1078 | void | |
1079 | _Bool | |
1080 | _Complex | |
1081 | _Imaginary | |
1082 | ||
1083 | ||
1084 | 1.3) Identifiers | |
1085 | ||
1086 | identifier: | |
1087 | identifier-nondigit | |
1088 | identifier identifier-nondigit | |
1089 | identifier digit | |
1090 | ||
1091 | identifier-nondigit: | |
1092 | nondigit | |
1093 | universal-character-name | |
1094 | any other implementation-defined characters | |
1095 | ||
1096 | nondigit: | |
1097 | _ | |
1098 | [a-zA-Z] /* regular expression */ | |
1099 | ||
1100 | digit: | |
1101 | [0-9] /* regular expression */ | |
1102 | ||
1103 | 1.4) Universal character names | |
1104 | ||
1105 | universal-character-name: | |
1106 | \u hex-quad | |
1107 | \U hex-quad hex-quad | |
1108 | ||
1109 | hex-quad: | |
1110 | hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit | |
1111 | ||
1112 | 1.5) Constants | |
1113 | ||
1114 | constant: | |
1115 | integer-constant | |
1116 | enumeration-constant | |
1117 | character-constant | |
1118 | ||
1119 | integer-constant: | |
1120 | decimal-constant integer-suffix-opt | |
1121 | octal-constant integer-suffix-opt | |
1122 | hexadecimal-constant integer-suffix-opt | |
1123 | ||
1124 | decimal-constant: | |
1125 | nonzero-digit | |
1126 | decimal-constant digit | |
1127 | ||
1128 | octal-constant: | |
1129 | 0 | |
1130 | octal-constant octal-digit | |
1131 | ||
1132 | hexadecimal-constant: | |
1133 | hexadecimal-prefix hexadecimal-digit | |
1134 | hexadecimal-constant hexadecimal-digit | |
1135 | ||
1136 | hexadecimal-prefix: | |
1137 | 0x | |
1138 | 0X | |
1139 | ||
1140 | nonzero-digit: | |
1141 | [1-9] | |
1142 | ||
1143 | integer-suffix: | |
1144 | unsigned-suffix long-suffix-opt | |
1145 | unsigned-suffix long-long-suffix | |
1146 | long-suffix unsigned-suffix-opt | |
1147 | long-long-suffix unsigned-suffix-opt | |
1148 | ||
1149 | unsigned-suffix: | |
1150 | u | |
1151 | U | |
1152 | ||
1153 | long-suffix: | |
1154 | l | |
1155 | L | |
1156 | ||
1157 | long-long-suffix: | |
1158 | ll | |
1159 | LL | |
1160 | ||
1161 | digit-sequence: | |
1162 | digit | |
1163 | digit-sequence digit | |
1164 | ||
1165 | hexadecimal-digit-sequence: | |
1166 | hexadecimal-digit | |
1167 | hexadecimal-digit-sequence hexadecimal-digit | |
1168 | ||
1169 | enumeration-constant: | |
1170 | identifier | |
1171 | string-literal | |
1172 | ||
1173 | character-constant: | |
1174 | ' c-char-sequence ' | |
1175 | L' c-char-sequence ' | |
1176 | ||
1177 | c-char-sequence: | |
1178 | c-char | |
1179 | c-char-sequence c-char | |
1180 | ||
1181 | c-char: | |
1182 | any member of source charset except single-quote ('), backslash | |
1183 | (\), or new-line character. | |
1184 | escape-sequence | |
1185 | ||
1186 | escape-sequence: | |
1187 | simple-escape-sequence | |
1188 | octal-escape-sequence | |
1189 | hexadecimal-escape-sequence | |
1190 | universal-character-name | |
1191 | ||
1192 | simple-escape-sequence: one of | |
1193 | \' \" \? \\ \a \b \f \n \r \t \v | |
1194 | ||
1195 | octal-escape-sequence: | |
1196 | \ octal-digit | |
1197 | \ octal-digit octal-digit | |
1198 | \ octal-digit octal-digit octal-digit | |
1199 | ||
1200 | hexadecimal-escape-sequence: | |
1201 | \x hexadecimal-digit | |
1202 | hexadecimal-escape-sequence hexadecimal-digit | |
1203 | ||
1204 | 1.6) String literals | |
1205 | ||
1206 | string-literal: | |
1207 | " s-char-sequence-opt " | |
1208 | L" s-char-sequence-opt " | |
1209 | ||
1210 | s-char-sequence: | |
1211 | s-char | |
1212 | s-char-sequence s-char | |
1213 | ||
1214 | s-char: | |
1215 | any member of source charset except double-quote ("), backslash | |
1216 | (\), or new-line character. | |
1217 | escape-sequence | |
1218 | ||
1219 | 1.7) Punctuators | |
1220 | ||
1221 | punctuator: one of | |
1222 | [ ] ( ) { } . -> * + - < > : ; ... = , | |
1223 | ||
1224 | ||
1225 | 2) Phrase structure grammar | |
1226 | ||
1227 | primary-expression: | |
1228 | identifier | |
1229 | constant | |
1230 | string-literal | |
1231 | ( unary-expression ) | |
1232 | ||
1233 | postfix-expression: | |
1234 | primary-expression | |
1235 | postfix-expression [ unary-expression ] | |
1236 | postfix-expression . identifier | |
1237 | postfix-expressoin -> identifier | |
1238 | ||
1239 | unary-expression: | |
1240 | postfix-expression | |
1241 | unary-operator postfix-expression | |
1242 | ||
1243 | unary-operator: one of | |
1244 | + - | |
1245 | ||
4fa992a5 MD |
1246 | assignment-operator: |
1247 | = | |
1248 | ||
b9606a77 MD |
1249 | type-assignment-operator: |
1250 | := | |
1251 | ||
4fa992a5 MD |
1252 | constant-expression: |
1253 | unary-expression | |
1254 | ||
1255 | constant-expression-range: | |
1256 | constant-expression ... constant-expression | |
1257 | ||
1258 | 2.2) Declarations: | |
1259 | ||
1260 | declaration: | |
689e04b4 | 1261 | declaration-specifiers declarator-list-opt ; |
4fa992a5 MD |
1262 | ctf-specifier ; |
1263 | ||
1264 | declaration-specifiers: | |
689e04b4 | 1265 | storage-class-specifier declaration-specifiers-opt |
4fa992a5 MD |
1266 | type-specifier declaration-specifiers-opt |
1267 | type-qualifier declaration-specifiers-opt | |
1268 | ||
1269 | declarator-list: | |
1270 | declarator | |
1271 | declarator-list , declarator | |
1272 | ||
d285084f MD |
1273 | abstract-declarator-list: |
1274 | abstract-declarator | |
1275 | abstract-declarator-list , abstract-declarator | |
1276 | ||
4fa992a5 MD |
1277 | storage-class-specifier: |
1278 | typedef | |
1279 | ||
1280 | type-specifier: | |
1281 | void | |
1282 | char | |
1283 | short | |
1284 | int | |
1285 | long | |
1286 | float | |
1287 | double | |
1288 | signed | |
1289 | unsigned | |
1290 | _Bool | |
1291 | _Complex | |
cfdd51ec | 1292 | _Imaginary |
9dfcfc0f MD |
1293 | struct-specifier |
1294 | variant-specifier | |
4fa992a5 MD |
1295 | enum-specifier |
1296 | typedef-name | |
1297 | ctf-type-specifier | |
1298 | ||
1299 | struct-specifier: | |
3b0f8e4d | 1300 | struct identifier-opt { struct-or-variant-declaration-list-opt } |
4fa992a5 MD |
1301 | struct identifier |
1302 | ||
1303 | struct-or-variant-declaration-list: | |
1304 | struct-or-variant-declaration | |
1305 | struct-or-variant-declaration-list struct-or-variant-declaration | |
1306 | ||
1307 | struct-or-variant-declaration: | |
1308 | specifier-qualifier-list struct-or-variant-declarator-list ; | |
550aca33 | 1309 | declaration-specifiers storage-class-specifier declaration-specifiers declarator-list ; |
38b8da21 MD |
1310 | typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list ; |
1311 | typealias declaration-specifiers abstract-declarator-list := declarator-list ; | |
4fa992a5 MD |
1312 | |
1313 | specifier-qualifier-list: | |
1314 | type-specifier specifier-qualifier-list-opt | |
1315 | type-qualifier specifier-qualifier-list-opt | |
1316 | ||
1317 | struct-or-variant-declarator-list: | |
1318 | struct-or-variant-declarator | |
1319 | struct-or-variant-declarator-list , struct-or-variant-declarator | |
1320 | ||
1321 | struct-or-variant-declarator: | |
1322 | declarator | |
1323 | declarator-opt : constant-expression | |
1324 | ||
1325 | variant-specifier: | |
1326 | variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list } | |
1327 | variant identifier variant-tag | |
1328 | ||
1329 | variant-tag: | |
1330 | < identifier > | |
1331 | ||
1332 | enum-specifier: | |
1333 | enum identifier-opt { enumerator-list } | |
1334 | enum identifier-opt { enumerator-list , } | |
1335 | enum identifier | |
a9b83695 MD |
1336 | enum identifier-opt : declaration-specifiers { enumerator-list } |
1337 | enum identifier-opt : declaration-specifiers { enumerator-list , } | |
4fa992a5 MD |
1338 | |
1339 | enumerator-list: | |
1340 | enumerator | |
1341 | enumerator-list , enumerator | |
1342 | ||
1343 | enumerator: | |
1344 | enumeration-constant | |
1345 | enumeration-constant = constant-expression | |
1346 | enumeration-constant = constant-expression-range | |
1347 | ||
1348 | type-qualifier: | |
1349 | const | |
1350 | ||
1351 | declarator: | |
1352 | pointer-opt direct-declarator | |
1353 | ||
1354 | direct-declarator: | |
1355 | identifier | |
1356 | ( declarator ) | |
1357 | direct-declarator [ type-specifier ] | |
1358 | direct-declarator [ constant-expression ] | |
1359 | ||
d285084f MD |
1360 | abstract-declarator: |
1361 | pointer-opt direct-abstract-declarator | |
1362 | ||
1363 | direct-abstract-declarator: | |
1364 | identifier-opt | |
1365 | ( abstract-declarator ) | |
1366 | direct-abstract-declarator [ type-specifier ] | |
1367 | direct-abstract-declarator [ constant-expression ] | |
1368 | direct-abstract-declarator [ ] | |
1369 | ||
4fa992a5 | 1370 | pointer: |
3b0f8e4d MD |
1371 | * type-qualifier-list-opt |
1372 | * type-qualifier-list-opt pointer | |
4fa992a5 MD |
1373 | |
1374 | type-qualifier-list: | |
1375 | type-qualifier | |
1376 | type-qualifier-list type-qualifier | |
1377 | ||
4fa992a5 MD |
1378 | typedef-name: |
1379 | identifier | |
1380 | ||
1381 | 2.3) CTF-specific declarations | |
1382 | ||
1383 | ctf-specifier: | |
1384 | event { ctf-assignment-expression-list-opt } | |
1385 | stream { ctf-assignment-expression-list-opt } | |
1386 | trace { ctf-assignment-expression-list-opt } | |
38b8da21 MD |
1387 | typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list ; |
1388 | typealias declaration-specifiers abstract-declarator-list := declarator-list ; | |
4fa992a5 MD |
1389 | |
1390 | ctf-type-specifier: | |
1391 | floating_point { ctf-assignment-expression-list-opt } | |
1392 | integer { ctf-assignment-expression-list-opt } | |
1393 | string { ctf-assignment-expression-list-opt } | |
1394 | ||
1395 | ctf-assignment-expression-list: | |
1396 | ctf-assignment-expression | |
1397 | ctf-assignment-expression-list ; ctf-assignment-expression | |
1398 | ||
1399 | ctf-assignment-expression: | |
1400 | unary-expression assignment-operator unary-expression | |
1401 | unary-expression type-assignment-operator type-specifier | |
550aca33 | 1402 | declaration-specifiers storage-class-specifier declaration-specifiers declarator-list |
38b8da21 MD |
1403 | typealias declaration-specifiers abstract-declarator-list := declaration-specifiers abstract-declarator-list |
1404 | typealias declaration-specifiers abstract-declarator-list := declarator-list |