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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 MD |
70 | An event stream is divided in contiguous event packets of variable size. These |
71 | subdivisions have a variable size. An event packet can contain a certain amount | |
72 | of padding at the end. The rationale for the event stream design choices is | |
73 | explained in Appendix B. Stream Header Rationale. | |
5ba9f198 | 74 | |
3bf79539 MD |
75 | An event stream is divided in contiguous event packets of variable size. These |
76 | subdivisions have a variable size. An event packet can contain a certain amount | |
77 | of padding at the end. The stream header is repeated at the beginning of each | |
78 | event packet. | |
5ba9f198 | 79 | |
3bf79539 MD |
80 | The event stream header will therefore be referred to as the "event packet |
81 | header" throughout the rest of this document. | |
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82 | |
83 | ||
84 | 4. Types | |
85 | ||
1fad7a85 MD |
86 | Types are organized as type classes. Each type class belong to either of two |
87 | kind of types: basic types or compound types. | |
88 | ||
5ba9f198 MD |
89 | 4.1 Basic types |
90 | ||
1fad7a85 MD |
91 | A basic type is a scalar type, as described in this section. It includes |
92 | integers, GNU/C bitfields, enumerations, and floating point values. | |
5ba9f198 MD |
93 | |
94 | 4.1.1 Type inheritance | |
95 | ||
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96 | Type specifications can be inherited to allow deriving types from a |
97 | type class. For example, see the uint32_t named type derived from the "integer" | |
98 | type class below ("Integers" section). Types have a precise binary | |
99 | representation in the trace. A type class has methods to read and write these | |
100 | types, but must be derived into a type to be usable in an event field. | |
5ba9f198 MD |
101 | |
102 | 4.1.2 Alignment | |
103 | ||
104 | We define "byte-packed" types as aligned on the byte size, namely 8-bit. | |
105 | We define "bit-packed" types as following on the next bit, as defined by the | |
106 | "bitfields" section. | |
5ba9f198 | 107 | |
3bf79539 MD |
108 | All basic types, except bitfields, are either aligned on an architecture-defined |
109 | specific alignment or byte-packed, depending on the architecture preference. | |
110 | Architectures providing fast unaligned write byte-packed basic types to save | |
5ba9f198 | 111 | space, aligning each type on byte boundaries (8-bit). Architectures with slow |
3bf79539 MD |
112 | unaligned writes align types on specific alignment values. If no specific |
113 | alignment is declared for a type nor its parents, it is assumed to be bit-packed | |
114 | for bitfields and byte-packed for other types. | |
5ba9f198 | 115 | |
3bf79539 | 116 | Metadata attribute representation of a specific alignment: |
5ba9f198 MD |
117 | |
118 | align = value; /* value in bits */ | |
119 | ||
120 | 4.1.3 Byte order | |
121 | ||
3bf79539 MD |
122 | By default, the native endianness of the source architecture the trace is used. |
123 | Byte order can be overridden for a basic type by specifying a "byte_order" | |
124 | attribute. Typical use-case is to specify the network byte order (big endian: | |
125 | "be") to save data captured from the network into the trace without conversion. | |
126 | If not specified, the byte order is native. | |
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127 | |
128 | Metadata representation: | |
129 | ||
130 | byte_order = native OR network OR be OR le; /* network and be are aliases */ | |
131 | ||
132 | 4.1.4 Size | |
133 | ||
134 | Type size, in bits, for integers and floats is that returned by "sizeof()" in C | |
135 | multiplied by CHAR_BIT. | |
136 | We require the size of "char" and "unsigned char" types (CHAR_BIT) to be fixed | |
137 | to 8 bits for cross-endianness compatibility. | |
138 | ||
139 | Metadata representation: | |
140 | ||
141 | size = value; (value is in bits) | |
142 | ||
143 | 4.1.5 Integers | |
144 | ||
145 | Signed integers are represented in two-complement. Integer alignment, size, | |
146 | signedness and byte ordering are defined in the metadata. Integers aligned on | |
147 | byte size (8-bit) and with length multiple of byte size (8-bit) correspond to | |
148 | the C99 standard integers. In addition, integers with alignment and/or size that | |
149 | are _not_ a multiple of the byte size are permitted; these correspond to the C99 | |
150 | standard bitfields, with the added specification that the CTF integer bitfields | |
151 | have a fixed binary representation. A MIT-licensed reference implementation of | |
152 | the CTF portable bitfields is available at: | |
153 | ||
154 | http://git.efficios.com/?p=babeltrace.git;a=blob;f=include/babeltrace/bitfield.h | |
155 | ||
156 | Binary representation of integers: | |
157 | ||
158 | - On little and big endian: | |
159 | - Within a byte, high bits correspond to an integer high bits, and low bits | |
160 | correspond to low bits. | |
161 | - On little endian: | |
162 | - Integer across multiple bytes are placed from the less significant to the | |
163 | most significant. | |
164 | - Consecutive integers are placed from lower bits to higher bits (even within | |
165 | a byte). | |
166 | - On big endian: | |
167 | - Integer across multiple bytes are placed from the most significant to the | |
168 | less significant. | |
169 | - Consecutive integers are placed from higher bits to lower bits (even within | |
170 | a byte). | |
171 | ||
172 | This binary representation is derived from the bitfield implementation in GCC | |
173 | for little and big endian. However, contrary to what GCC does, integers can | |
174 | cross units boundaries (no padding is required). Padding can be explicitely | |
175 | added (see 4.1.6 GNU/C bitfields) to follow the GCC layout if needed. | |
176 | ||
177 | Metadata representation: | |
178 | ||
80fd2569 | 179 | integer { |
5ba9f198 MD |
180 | signed = true OR false; /* default false */ |
181 | byte_order = native OR network OR be OR le; /* default native */ | |
182 | size = value; /* value in bits, no default */ | |
183 | align = value; /* value in bits */ | |
2152348f | 184 | } |
5ba9f198 | 185 | |
80fd2569 | 186 | Example of type inheritance (creation of a uint32_t named type): |
5ba9f198 | 187 | |
359894ac | 188 | typealias integer { |
9e4e34e9 | 189 | size = 32; |
5ba9f198 MD |
190 | signed = false; |
191 | align = 32; | |
359894ac | 192 | } : uint32_t; |
5ba9f198 | 193 | |
80fd2569 | 194 | Definition of a named 5-bit signed bitfield: |
5ba9f198 | 195 | |
359894ac | 196 | typealias integer { |
5ba9f198 MD |
197 | size = 5; |
198 | signed = true; | |
199 | align = 1; | |
359894ac | 200 | } : int5_t; |
5ba9f198 MD |
201 | |
202 | 4.1.6 GNU/C bitfields | |
203 | ||
204 | The GNU/C bitfields follow closely the integer representation, with a | |
205 | particularity on alignment: if a bitfield cannot fit in the current unit, the | |
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206 | unit is padded and the bitfield starts at the following unit. The unit size is |
207 | defined by the size of the type "unit_type". | |
5ba9f198 | 208 | |
2152348f | 209 | Metadata representation: |
80fd2569 MD |
210 | |
211 | unit_type name:size: | |
212 | ||
5ba9f198 MD |
213 | As an example, the following structure declared in C compiled by GCC: |
214 | ||
215 | struct example { | |
216 | short a:12; | |
217 | short b:5; | |
218 | }; | |
219 | ||
2152348f MD |
220 | The example structure is aligned on the largest element (short). The second |
221 | bitfield would be aligned on the next unit boundary, because it would not fit in | |
222 | the current unit. | |
5ba9f198 MD |
223 | |
224 | 4.1.7 Floating point | |
225 | ||
226 | The floating point values byte ordering is defined in the metadata. | |
227 | ||
228 | Floating point values follow the IEEE 754-2008 standard interchange formats. | |
229 | Description of the floating point values include the exponent and mantissa size | |
230 | in bits. Some requirements are imposed on the floating point values: | |
231 | ||
232 | - FLT_RADIX must be 2. | |
233 | - mant_dig is the number of digits represented in the mantissa. It is specified | |
234 | by the ISO C99 standard, section 5.2.4, as FLT_MANT_DIG, DBL_MANT_DIG and | |
235 | LDBL_MANT_DIG as defined by <float.h>. | |
236 | - exp_dig is the number of digits represented in the exponent. Given that | |
237 | mant_dig is one bit more than its actual size in bits (leading 1 is not | |
238 | needed) and also given that the sign bit always takes one bit, exp_dig can be | |
239 | specified as: | |
240 | ||
241 | - sizeof(float) * CHAR_BIT - FLT_MANT_DIG | |
242 | - sizeof(double) * CHAR_BIT - DBL_MANT_DIG | |
243 | - sizeof(long double) * CHAR_BIT - LDBL_MANT_DIG | |
244 | ||
245 | Metadata representation: | |
246 | ||
80fd2569 | 247 | floating_point { |
5ba9f198 MD |
248 | exp_dig = value; |
249 | mant_dig = value; | |
250 | byte_order = native OR network OR be OR le; | |
2152348f | 251 | } |
5ba9f198 MD |
252 | |
253 | Example of type inheritance: | |
254 | ||
359894ac | 255 | typealias floating_point { |
5ba9f198 MD |
256 | exp_dig = 8; /* sizeof(float) * CHAR_BIT - FLT_MANT_DIG */ |
257 | mant_dig = 24; /* FLT_MANT_DIG */ | |
258 | byte_order = native; | |
359894ac | 259 | } : float; |
5ba9f198 MD |
260 | |
261 | TODO: define NaN, +inf, -inf behavior. | |
262 | ||
263 | 4.1.8 Enumerations | |
264 | ||
265 | Enumerations are a mapping between an integer type and a table of strings. The | |
266 | numerical representation of the enumeration follows the integer type specified | |
267 | by the metadata. The enumeration mapping table is detailed in the enumeration | |
3bf79539 MD |
268 | description within the metadata. The mapping table maps inclusive value ranges |
269 | (or single values) to strings. Instead of being limited to simple | |
270 | "value -> string" mappings, these enumerations map | |
80fd2569 | 271 | "[ start_value ... end_value ] -> string", which map inclusive ranges of |
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272 | values to strings. An enumeration from the C language can be represented in |
273 | this format by having the same start_value and end_value for each element, which | |
274 | is in fact a range of size 1. This single-value range is supported without | |
4767a9e7 | 275 | repeating the start and end values with the value = string declaration. |
80fd2569 | 276 | |
4767a9e7 MD |
277 | If a numeric value is encountered between < >, it represents the integer type |
278 | size used to hold the enumeration, in bits. | |
279 | ||
cfc73fdc | 280 | enum name <integer_type OR size> { |
359894ac | 281 | somestring = start_value1 ... end_value1, |
80fd2569 MD |
282 | "other string" = start_value2 ... end_value2, |
283 | yet_another_string, /* will be assigned to end_value2 + 1 */ | |
284 | "some other string" = value, | |
285 | ... | |
286 | }; | |
287 | ||
288 | If the values are omitted, the enumeration starts at 0 and increment of 1 for | |
289 | each entry: | |
290 | ||
cfc73fdc | 291 | enum name <32> { |
80fd2569 MD |
292 | ZERO, |
293 | ONE, | |
294 | TWO, | |
295 | TEN = 10, | |
296 | ELEVEN, | |
3bf79539 | 297 | }; |
5ba9f198 | 298 | |
80fd2569 | 299 | Overlapping ranges within a single enumeration are implementation defined. |
5ba9f198 | 300 | |
2152348f MD |
301 | A nameless enumeration can be declared as a field type or as part of a typedef: |
302 | ||
303 | enum <integer_type> { | |
304 | ... | |
305 | } | |
306 | ||
1fad7a85 | 307 | |
5ba9f198 MD |
308 | 4.2 Compound types |
309 | ||
1fad7a85 MD |
310 | Compound are aggregation of type declarations. Compound types include |
311 | structures, variant, arrays, sequences, and strings. | |
312 | ||
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313 | 4.2.1 Structures |
314 | ||
315 | Structures are aligned on the largest alignment required by basic types | |
316 | contained within the structure. (This follows the ISO/C standard for structures) | |
317 | ||
80fd2569 | 318 | Metadata representation of a named structure: |
5ba9f198 | 319 | |
80fd2569 MD |
320 | struct name { |
321 | field_type field_name; | |
322 | field_type field_name; | |
323 | ... | |
324 | }; | |
5ba9f198 MD |
325 | |
326 | Example: | |
327 | ||
80fd2569 MD |
328 | struct example { |
329 | integer { /* Nameless type */ | |
330 | size = 16; | |
331 | signed = true; | |
332 | align = 16; | |
333 | } first_field_name; | |
334 | uint64_t second_field_name; /* Named type declared in the metadata */ | |
3bf79539 | 335 | }; |
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336 | |
337 | The fields are placed in a sequence next to each other. They each possess a | |
338 | field name, which is a unique identifier within the structure. | |
339 | ||
2152348f | 340 | A nameless structure can be declared as a field type or as part of a typedef: |
80fd2569 MD |
341 | |
342 | struct { | |
343 | ... | |
2152348f | 344 | } |
80fd2569 | 345 | |
77a98c82 | 346 | 4.2.2 Variants (Discriminated/Tagged Unions) |
fcba70d4 | 347 | |
fdf2bb05 MD |
348 | A CTF variant is a selection between different types. A CTF variant must |
349 | always be defined within the scope of a structure or within fields | |
350 | contained within a structure (defined recursively). A "tag" enumeration | |
351 | field must appear in either the same lexical scope, prior to the variant | |
352 | field (in field declaration order), in an uppermost lexical scope (see | |
353 | Section 7.2.1), or in an uppermost dynamic scope (see Section 7.2.2). | |
354 | The type selection is indicated by the mapping from the enumeration | |
355 | value to the string used as variant type selector. The field to use as | |
356 | tag is specified by the "tag_field", specified between "< >" after the | |
357 | "variant" keyword for unnamed variants, and after "variant name" for | |
358 | named variants. | |
fcba70d4 MD |
359 | |
360 | The alignment of the variant is the alignment of the type as selected by the tag | |
361 | value for the specific instance of the variant. The alignment of the type | |
362 | containing the variant is independent of the variant alignment. The size of the | |
363 | variant is the size as selected by the tag value for the specific instance of | |
364 | the variant. | |
365 | ||
366 | A named variant declaration followed by its definition within a structure | |
367 | declaration: | |
368 | ||
369 | variant name { | |
370 | field_type sel1; | |
371 | field_type sel2; | |
372 | field_type sel3; | |
373 | ... | |
374 | }; | |
375 | ||
376 | struct { | |
377 | enum <integer_type or size> { sel1, sel2, sel3, ... } tag_field; | |
378 | ... | |
379 | variant name <tag_field> v; | |
380 | } | |
381 | ||
382 | An unnamed variant definition within a structure is expressed by the following | |
383 | metadata: | |
384 | ||
385 | struct { | |
386 | enum <integer_type or size> { sel1, sel2, sel3, ... } tag_field; | |
387 | ... | |
388 | variant <tag_field> { | |
389 | field_type sel1; | |
390 | field_type sel2; | |
391 | field_type sel3; | |
392 | ... | |
393 | } v; | |
394 | } | |
395 | ||
396 | Example of a named variant within a sequence that refers to a single tag field: | |
397 | ||
398 | variant example { | |
399 | uint32_t a; | |
400 | uint64_t b; | |
401 | short c; | |
402 | }; | |
403 | ||
404 | struct { | |
405 | enum <uint2_t> { a, b, c } choice; | |
15850440 | 406 | variant example <choice> v[unsigned int]; |
fcba70d4 MD |
407 | } |
408 | ||
409 | Example of an unnamed variant: | |
410 | ||
411 | struct { | |
412 | enum <uint2_t> { a, b, c, d } choice; | |
413 | /* Unrelated fields can be added between the variant and its tag */ | |
414 | int32_t somevalue; | |
415 | variant <choice> { | |
416 | uint32_t a; | |
417 | uint64_t b; | |
418 | short c; | |
419 | struct { | |
420 | unsigned int field1; | |
421 | uint64_t field2; | |
422 | } d; | |
423 | } s; | |
424 | } | |
425 | ||
426 | Example of an unnamed variant within an array: | |
427 | ||
428 | struct { | |
429 | enum <uint2_t> { a, b, c } choice; | |
430 | variant <choice> { | |
431 | uint32_t a; | |
432 | uint64_t b; | |
433 | short c; | |
15850440 | 434 | } v[10]; |
fcba70d4 MD |
435 | } |
436 | ||
437 | Example of a variant type definition within a structure, where the defined type | |
438 | is then declared within an array of structures. This variant refers to a tag | |
439 | located in an upper lexical scope. This example clearly shows that a variant | |
440 | type definition referring to the tag "x" uses the closest preceding field from | |
441 | the lexical scope of the type definition. | |
442 | ||
443 | struct { | |
444 | enum <uint2_t> { a, b, c, d } x; | |
445 | ||
446 | typedef variant <x> { /* | |
447 | * "x" refers to the preceding "x" enumeration in the | |
448 | * lexical scope of the type definition. | |
449 | */ | |
450 | uint32_t a; | |
451 | uint64_t b; | |
452 | short c; | |
453 | } example_variant; | |
454 | ||
455 | struct { | |
456 | enum <int> { x, y, z } x; /* This enumeration is not used by "v". */ | |
457 | example_variant v; /* | |
458 | * "v" uses the "enum <uint2_t> { a, b, c, d }" | |
459 | * tag. | |
460 | */ | |
461 | } a[10]; | |
462 | } | |
463 | ||
464 | 4.2.3 Arrays | |
5ba9f198 MD |
465 | |
466 | Arrays are fixed-length. Their length is declared in the type declaration within | |
467 | the metadata. They contain an array of "inner type" elements, which can refer to | |
468 | any type not containing the type of the array being declared (no circular | |
3bf79539 | 469 | dependency). The length is the number of elements in an array. |
5ba9f198 | 470 | |
2152348f | 471 | Metadata representation of a named array: |
80fd2569 MD |
472 | |
473 | typedef elem_type name[length]; | |
5ba9f198 | 474 | |
2152348f | 475 | A nameless array can be declared as a field type within a structure, e.g.: |
5ba9f198 | 476 | |
2152348f | 477 | uint8_t field_name[10]; |
80fd2569 | 478 | |
5ba9f198 | 479 | |
fcba70d4 | 480 | 4.2.4 Sequences |
5ba9f198 MD |
481 | |
482 | Sequences are dynamically-sized arrays. They start with an integer that specify | |
483 | the length of the sequence, followed by an array of "inner type" elements. | |
3bf79539 | 484 | The length is the number of elements in the sequence. |
5ba9f198 | 485 | |
2152348f | 486 | Metadata representation for a named sequence: |
80fd2569 MD |
487 | |
488 | typedef elem_type name[length_type]; | |
489 | ||
490 | A nameless sequence can be declared as a field type, e.g.: | |
491 | ||
80fd2569 MD |
492 | long field_name[int]; |
493 | ||
494 | The length type follows the integer types specifications, and the sequence | |
5ba9f198 MD |
495 | elements follow the "array" specifications. |
496 | ||
fcba70d4 | 497 | 4.2.5 Strings |
5ba9f198 MD |
498 | |
499 | Strings are an array of bytes of variable size and are terminated by a '\0' | |
500 | "NULL" character. Their encoding is described in the metadata. In absence of | |
501 | encoding attribute information, the default encoding is UTF-8. | |
502 | ||
80fd2569 MD |
503 | Metadata representation of a named string type: |
504 | ||
359894ac | 505 | typealias string { |
5ba9f198 | 506 | encoding = UTF8 OR ASCII; |
359894ac | 507 | } : name; |
5ba9f198 | 508 | |
80fd2569 MD |
509 | A nameless string type can be declared as a field type: |
510 | ||
511 | string field_name; /* Use default UTF8 encoding */ | |
5ba9f198 | 512 | |
3bf79539 MD |
513 | 5. Event Packet Header |
514 | ||
515 | The event packet header consists of two part: one is mandatory and have a fixed | |
516 | layout. The second part, the "event packet context", has its layout described in | |
517 | the metadata. | |
5ba9f198 | 518 | |
3bf79539 MD |
519 | - Aligned on page size. Fixed size. Fields either aligned or packed (depending |
520 | on the architecture preference). | |
521 | No padding at the end of the event packet header. Native architecture byte | |
5ba9f198 | 522 | ordering. |
3bf79539 MD |
523 | |
524 | Fixed layout (event packet header): | |
525 | ||
5ba9f198 MD |
526 | - Magic number (CTF magic numbers: 0xC1FC1FC1 and its reverse endianness |
527 | representation: 0xC11FFCC1) It needs to have a non-symmetric bytewise | |
528 | representation. Used to distinguish between big and little endian traces (this | |
529 | information is determined by knowing the endianness of the architecture | |
530 | reading the trace and comparing the magic number against its value and the | |
531 | reverse, 0xC11FFCC1). This magic number specifies that we use the CTF metadata | |
532 | description language described in this document. Different magic numbers | |
533 | should be used for other metadata description languages. | |
3bf79539 | 534 | - Trace UUID, used to ensure the event packet match the metadata used. |
5ba9f198 MD |
535 | (note: we cannot use a metadata checksum because metadata can be appended to |
536 | while tracing is active) | |
3bf79539 MD |
537 | - Stream ID, used as reference to stream description in metadata. |
538 | ||
539 | Metadata-defined layout (event packet context): | |
540 | ||
541 | - Event packet content size (in bytes). | |
542 | - Event packet size (in bytes, includes padding). | |
543 | - Event packet content checksum (optional). Checksum excludes the event packet | |
544 | header. | |
545 | - Per-stream event packet sequence count (to deal with UDP packet loss). The | |
546 | number of significant sequence counter bits should also be present, so | |
547 | wrap-arounds are deal with correctly. | |
548 | - Timestamp at the beginning and timestamp at the end of the event packet. | |
549 | Both timestamps are written in the packet header, but sampled respectively | |
550 | while (or before) writing the first event and while (or after) writing the | |
551 | last event in the packet. The inclusive range between these timestamps should | |
552 | include all event timestamps assigned to events contained within the packet. | |
5ba9f198 | 553 | - Events discarded count |
3bf79539 MD |
554 | - Snapshot of a per-stream free-running counter, counting the number of |
555 | events discarded that were supposed to be written in the stream prior to | |
556 | the first event in the event packet. | |
5ba9f198 | 557 | * Note: producer-consumer buffer full condition should fill the current |
3bf79539 | 558 | event packet with padding so we know exactly where events have been |
5ba9f198 | 559 | discarded. |
3bf79539 MD |
560 | - Lossless compression scheme used for the event packet content. Applied |
561 | directly to raw data. New types of compression can be added in following | |
562 | versions of the format. | |
5ba9f198 MD |
563 | 0: no compression scheme |
564 | 1: bzip2 | |
565 | 2: gzip | |
3bf79539 MD |
566 | 3: xz |
567 | - Cypher used for the event packet content. Applied after compression. | |
5ba9f198 MD |
568 | 0: no encryption |
569 | 1: AES | |
3bf79539 | 570 | - Checksum scheme used for the event packet content. Applied after encryption. |
5ba9f198 MD |
571 | 0: no checksum |
572 | 1: md5 | |
573 | 2: sha1 | |
574 | 3: crc32 | |
575 | ||
3bf79539 MD |
576 | 5.1 Event Packet Header Fixed Layout Description |
577 | ||
80fd2569 MD |
578 | struct event_packet_header { |
579 | uint32_t magic; | |
580 | uint8_t trace_uuid[16]; | |
3bf79539 | 581 | uint32_t stream_id; |
80fd2569 | 582 | }; |
5ba9f198 | 583 | |
3bf79539 MD |
584 | 5.2 Event Packet Context Description |
585 | ||
586 | Event packet context example. These are declared within the stream declaration | |
587 | in the metadata. All these fields are optional except for "content_size" and | |
588 | "packet_size", which must be present in the context. | |
589 | ||
590 | An example event packet context type: | |
591 | ||
80fd2569 | 592 | struct event_packet_context { |
3bf79539 MD |
593 | uint64_t timestamp_begin; |
594 | uint64_t timestamp_end; | |
595 | uint32_t checksum; | |
596 | uint32_t stream_packet_count; | |
597 | uint32_t events_discarded; | |
598 | uint32_t cpu_id; | |
599 | uint32_t/uint16_t content_size; | |
600 | uint32_t/uint16_t packet_size; | |
601 | uint8_t stream_packet_count_bits; /* Significant counter bits */ | |
602 | uint8_t compression_scheme; | |
603 | uint8_t encryption_scheme; | |
3b0f8e4d | 604 | uint8_t checksum_scheme; |
3bf79539 | 605 | }; |
5ba9f198 | 606 | |
fcba70d4 | 607 | |
5ba9f198 MD |
608 | 6. Event Structure |
609 | ||
610 | The overall structure of an event is: | |
611 | ||
fcba70d4 | 612 | 1 - Stream Packet Context (as specified by the stream metadata) |
fdf2bb05 MD |
613 | 2 - Event Header (as specified by the stream metadata) |
614 | 3 - Stream Event Context (as specified by the stream metadata) | |
615 | 4 - Event Context (as specified by the event metadata) | |
616 | 5 - Event Payload (as specified by the event metadata) | |
5ba9f198 | 617 | |
fdf2bb05 | 618 | This structure defines an implicit dynamic scoping, where variants |
7d9d7e92 MD |
619 | located in inner structures (those with a higher number in the listing |
620 | above) can refer to the fields of outer structures (with lower number in | |
621 | the listing above). See Section 7.2 Metadata Scopes for more detail. | |
5ba9f198 | 622 | |
fdf2bb05 | 623 | 6.1 Event Header |
fcba70d4 MD |
624 | |
625 | Event headers can be described within the metadata. We hereby propose, as an | |
626 | example, two types of events headers. Type 1 accommodates streams with less than | |
627 | 31 event IDs. Type 2 accommodates streams with 31 or more event IDs. | |
5ba9f198 | 628 | |
3bf79539 MD |
629 | One major factor can vary between streams: the number of event IDs assigned to |
630 | a stream. Luckily, this information tends to stay relatively constant (modulo | |
5ba9f198 | 631 | event registration while trace is being recorded), so we can specify different |
3bf79539 | 632 | representations for streams containing few event IDs and streams containing |
5ba9f198 MD |
633 | many event IDs, so we end up representing the event ID and timestamp as densely |
634 | as possible in each case. | |
635 | ||
fcba70d4 MD |
636 | The header is extended in the rare occasions where the information cannot be |
637 | represented in the ranges available in the standard event header. They are also | |
3bf79539 MD |
638 | used in the rare occasions where the data required for a field could not be |
639 | collected: the flag corresponding to the missing field within the missing_fields | |
640 | array is then set to 1. | |
5ba9f198 MD |
641 | |
642 | Types uintX_t represent an X-bit unsigned integer. | |
643 | ||
644 | ||
fdf2bb05 | 645 | 6.1.1 Type 1 - Few event IDs |
5ba9f198 MD |
646 | |
647 | - Aligned on 32-bit (or 8-bit if byte-packed, depending on the architecture | |
648 | preference). | |
5ba9f198 | 649 | - Native architecture byte ordering. |
fcba70d4 MD |
650 | - For "compact" selection |
651 | - Fixed size: 32 bits. | |
652 | - For "extended" selection | |
653 | - Size depends on the architecture and variant alignment. | |
5ba9f198 | 654 | |
80fd2569 | 655 | struct event_header_1 { |
fcba70d4 MD |
656 | /* |
657 | * id: range: 0 - 30. | |
658 | * id 31 is reserved to indicate an extended header. | |
659 | */ | |
660 | enum <uint5_t> { compact = 0 ... 30, extended = 31 } id; | |
661 | variant <id> { | |
662 | struct { | |
663 | uint27_t timestamp; | |
664 | } compact; | |
665 | struct { | |
666 | uint32_t id; /* 32-bit event IDs */ | |
667 | uint64_t timestamp; /* 64-bit timestamps */ | |
668 | } extended; | |
669 | } v; | |
5ba9f198 MD |
670 | }; |
671 | ||
5ba9f198 | 672 | |
fdf2bb05 | 673 | 6.1.2 Type 2 - Many event IDs |
5ba9f198 | 674 | |
fcba70d4 | 675 | - Aligned on 16-bit (or 8-bit if byte-packed, depending on the architecture |
5ba9f198 | 676 | preference). |
5ba9f198 | 677 | - Native architecture byte ordering. |
fcba70d4 MD |
678 | - For "compact" selection |
679 | - Size depends on the architecture and variant alignment. | |
680 | - For "extended" selection | |
681 | - Size depends on the architecture and variant alignment. | |
5ba9f198 | 682 | |
80fd2569 | 683 | struct event_header_2 { |
fcba70d4 MD |
684 | /* |
685 | * id: range: 0 - 65534. | |
686 | * id 65535 is reserved to indicate an extended header. | |
687 | */ | |
688 | enum <uint16_t> { compact = 0 ... 65534, extended = 65535 } id; | |
689 | variant <id> { | |
690 | struct { | |
691 | uint32_t timestamp; | |
692 | } compact; | |
693 | struct { | |
694 | uint32_t id; /* 32-bit event IDs */ | |
695 | uint64_t timestamp; /* 64-bit timestamps */ | |
696 | } extended; | |
697 | } v; | |
5ba9f198 MD |
698 | }; |
699 | ||
5ba9f198 MD |
700 | |
701 | 6.2 Event Context | |
702 | ||
703 | The event context contains information relative to the current event. The choice | |
fcba70d4 MD |
704 | and meaning of this information is specified by the metadata "stream" and |
705 | "event" information. The "stream" context is applied to all events within the | |
706 | stream. The "stream" context structure follows the event header. The "event" | |
707 | context is applied to specific events. Its structure follows the "stream" | |
708 | context stucture. | |
5ba9f198 | 709 | |
fcba70d4 MD |
710 | An example of stream-level event context is to save the event payload size with |
711 | each event, or to save the current PID with each event. These are declared | |
712 | within the stream declaration within the metadata: | |
5ba9f198 | 713 | |
fcba70d4 MD |
714 | stream { |
715 | ... | |
716 | event { | |
717 | ... | |
4fa992a5 | 718 | context := struct { |
80fd2569 MD |
719 | uint pid; |
720 | uint16_t payload_size; | |
3bf79539 | 721 | }; |
fcba70d4 MD |
722 | } |
723 | }; | |
724 | ||
725 | An example of event-specific event context is to declare a bitmap of missing | |
726 | fields, only appended after the stream event context if the extended event | |
727 | header is selected. NR_FIELDS is the number of fields within the event (a | |
728 | numeric value). | |
5ba9f198 | 729 | |
fcba70d4 MD |
730 | event { |
731 | context = struct { | |
732 | variant <id> { | |
733 | struct { } compact; | |
734 | struct { | |
735 | uint1_t missing_fields[NR_FIELDS]; /* missing event fields bitmap */ | |
736 | } extended; | |
737 | } v; | |
738 | }; | |
739 | ... | |
740 | } | |
5ba9f198 MD |
741 | |
742 | 6.3 Event Payload | |
743 | ||
744 | An event payload contains fields specific to a given event type. The fields | |
745 | belonging to an event type are described in the event-specific metadata | |
746 | within a structure type. | |
747 | ||
748 | 6.3.1 Padding | |
749 | ||
750 | No padding at the end of the event payload. This differs from the ISO/C standard | |
751 | for structures, but follows the CTF standard for structures. In a trace, even | |
752 | though it makes sense to align the beginning of a structure, it really makes no | |
753 | sense to add padding at the end of the structure, because structures are usually | |
754 | not followed by a structure of the same type. | |
755 | ||
756 | This trick can be done by adding a zero-length "end" field at the end of the C | |
757 | structures, and by using the offset of this field rather than using sizeof() | |
3bf79539 | 758 | when calculating the size of a structure (see Appendix "A. Helper macros"). |
5ba9f198 MD |
759 | |
760 | 6.3.2 Alignment | |
761 | ||
762 | The event payload is aligned on the largest alignment required by types | |
763 | contained within the payload. (This follows the ISO/C standard for structures) | |
764 | ||
765 | ||
5ba9f198 MD |
766 | 7. Metadata |
767 | ||
3bf79539 MD |
768 | The meta-data is located in a stream named "metadata". It is made of "event |
769 | packets", which each start with an event packet header. The event type within | |
770 | the metadata stream have no event header nor event context. Each event only | |
5ba9f198 | 771 | contains a null-terminated "string" payload, which is a metadata description |
3bf79539 MD |
772 | entry. The events are packed one next to another. Each event packet start with |
773 | an event packet header, which contains, amongst other fields, the magic number | |
fdf2bb05 MD |
774 | and trace UUID. The trace UUID is represented as a string of hexadecimal digits |
775 | and dashes "-". | |
5ba9f198 MD |
776 | |
777 | The metadata can be parsed by reading through the metadata strings, skipping | |
fcba70d4 MD |
778 | newlines and null-characters. Type names are made of a single identifier, and |
779 | can be surrounded by prefix/postfix. Text contained within "/*" and "*/", as | |
c6d7abc5 MD |
780 | well as within "//" and end of line, are treated as comments. Boolean values can |
781 | be represented as true, TRUE, or 1 for true, and false, FALSE, or 0 for false. | |
fcba70d4 | 782 | |
fdf2bb05 MD |
783 | |
784 | 7.1 Declaration vs Definition | |
785 | ||
786 | A declaration associates a layout to a type, without specifying where | |
787 | this type is located in the event structure hierarchy (see Section 6). | |
788 | This therefore includes typedef, typealias, as well as all type | |
789 | specifiers. In certain circumstances (typedef, structure field and | |
790 | variant field), a declaration is followed by a declarator, which specify | |
791 | the newly defined type name (for typedef), or the field name (for | |
792 | declarations located within structure and variants). Array and sequence, | |
793 | declared with square brackets ("[" "]"), are part of the declarator, | |
457d8b0a MD |
794 | similarly to C99. The enumeration type specifier and variant tag name |
795 | (both specified with "<" ">") are part of the type specifier. | |
fdf2bb05 MD |
796 | |
797 | A definition associates a type to a location in the event structure | |
798 | hierarchy (see Section 6). | |
799 | ||
800 | ||
801 | 7.2 Metadata Scopes | |
802 | ||
803 | CTF metadata uses two different types of scoping: a lexical scope is | |
804 | used for declarations and type definitions, and a dynamic scope is used | |
805 | for variants references to tag fields. | |
806 | ||
807 | 7.2.1 Lexical Scope | |
808 | ||
d285084f MD |
809 | Each of "trace", "stream", "event", "struct" and "variant" have their own |
810 | nestable declaration scope, within which types can be declared using "typedef" | |
fdf2bb05 | 811 | and "typealias". A root declaration scope also contains all declarations |
7d9d7e92 | 812 | located outside of any of the aforementioned declarations. An inner |
fdf2bb05 | 813 | declaration scope can refer to type declared within its container |
7d9d7e92 MD |
814 | lexical scope prior to the inner declaration scope. Redefinition of a |
815 | typedef or typealias is not valid, although hiding an upper scope | |
fdf2bb05 MD |
816 | typedef or typealias is allowed within a sub-scope. |
817 | ||
818 | 7.2.2 Dynamic Scope | |
819 | ||
7d9d7e92 MD |
820 | A dynamic scope consists in the lexical scope augmented with the |
821 | implicit event structure definition hierarchy presented at Section 6. | |
822 | The dynamic scope is only used for variant tag definitions. It is used | |
823 | at definition time to look up the location of the tag field associated | |
824 | with a variant. | |
825 | ||
826 | Therefore, variants in lower levels in the dynamic scope (e.g. event | |
827 | context) can refer to a tag field located in upper levels (e.g. in the | |
828 | event header) by specifying, in this case, the associated tag with | |
829 | <header.field_name>. This allows, for instance, the event context to | |
830 | define a variant referring to the "id" field of the event header as | |
831 | selector. | |
fdf2bb05 MD |
832 | |
833 | The target dynamic scope must be specified explicitly when referring to | |
834 | a field outside of the local static scope. The dynamic scope prefixes | |
835 | are thus: | |
836 | ||
7d9d7e92 MD |
837 | - Stream Packet Context: <stream.packet.context. >, |
838 | - Event Header: <stream.event.header. >, | |
839 | - Stream Event Context: <stream.event.context. >, | |
840 | - Event Context: <event.context. >, | |
841 | - Event Payload: <event.fields. >. | |
fdf2bb05 MD |
842 | |
843 | Multiple declarations of the same field name within a single scope is | |
844 | not valid. It is however valid to re-use the same field name in | |
845 | different scopes. There is no possible conflict, because the dynamic | |
846 | scope must be specified when a variant refers to a tag field located in | |
847 | a different dynamic scope. | |
848 | ||
457d8b0a MD |
849 | The information available in the dynamic scopes can be thought of as the |
850 | current tracing context. At trace production, information about the | |
851 | current context is saved into the specified scope field levels. At trace | |
852 | consumption, for each event, the current trace context is therefore | |
853 | readable by accessing the upper dynamic scopes. | |
854 | ||
fdf2bb05 MD |
855 | |
856 | 7.2 Metadata Examples | |
d285084f | 857 | |
fcba70d4 | 858 | The grammar representing the CTF metadata is presented in |
fdf2bb05 MD |
859 | Appendix C. CTF Metadata Grammar. This section presents a rather ligher |
860 | reading that consists in examples of CTF metadata, with template values: | |
5ba9f198 MD |
861 | |
862 | trace { | |
fdf2bb05 | 863 | major = value; /* Trace format version */ |
5ba9f198 | 864 | minor = value; |
fdf2bb05 | 865 | uuid = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"; /* Trace UUID */ |
3bf79539 MD |
866 | word_size = value; |
867 | }; | |
5ba9f198 | 868 | |
3bf79539 MD |
869 | stream { |
870 | id = stream_id; | |
fdf2bb05 | 871 | /* Type 1 - Few event IDs; Type 2 - Many event IDs. See section 6.1. */ |
4fa992a5 MD |
872 | event.header := event_header_1 OR event_header_2; |
873 | event.context := struct { | |
77a98c82 | 874 | ... |
3bf79539 | 875 | }; |
4fa992a5 | 876 | packet.context := struct { |
77a98c82 | 877 | ... |
3bf79539 MD |
878 | }; |
879 | }; | |
5ba9f198 MD |
880 | |
881 | event { | |
3d13ef1a | 882 | name = event_name; |
3bf79539 MD |
883 | id = value; /* Numeric identifier within the stream */ |
884 | stream = stream_id; | |
4fa992a5 | 885 | context := struct { |
fcba70d4 MD |
886 | ... |
887 | }; | |
4fa992a5 | 888 | fields := struct { |
80fd2569 MD |
889 | ... |
890 | }; | |
3bf79539 | 891 | }; |
5ba9f198 MD |
892 | |
893 | /* More detail on types in section 4. Types */ | |
894 | ||
3d13ef1a MD |
895 | /* |
896 | * Named types: | |
897 | * | |
4fa992a5 | 898 | * Type declarations behave similarly to the C standard. |
3d13ef1a MD |
899 | */ |
900 | ||
901 | typedef aliased_type_prefix aliased_type new_type aliased_type_postfix; | |
2152348f | 902 | |
3d13ef1a | 903 | /* e.g.: typedef struct example new_type_name[10]; */ |
80fd2569 | 904 | |
4fa992a5 MD |
905 | /* |
906 | * typealias | |
907 | * | |
908 | * The "typealias" declaration can be used to give a name (including | |
359894ac MD |
909 | * prefix/postfix) to a type. It should also be used to map basic C types |
910 | * (float, int, unsigned long, ...) to a CTF type. Typealias is a superset of | |
911 | * "typedef": it also allows assignment of a simple variable identifier to a | |
912 | * type. | |
4fa992a5 MD |
913 | */ |
914 | ||
915 | typealias type_class { | |
80fd2569 | 916 | ... |
fcba70d4 | 917 | } : new_type_prefix new_type new_type_postfix; |
2152348f | 918 | |
3d13ef1a MD |
919 | /* |
920 | * e.g.: | |
4fa992a5 | 921 | * typealias integer { |
3d13ef1a MD |
922 | * size = 32; |
923 | * align = 32; | |
924 | * signed = false; | |
fcba70d4 | 925 | * } : struct page *; |
359894ac MD |
926 | * |
927 | * typealias integer { | |
928 | * size = 32; | |
929 | * align = 32; | |
930 | * signed = true; | |
931 | * } : int; | |
3d13ef1a | 932 | */ |
80fd2569 MD |
933 | |
934 | struct name { | |
3bf79539 MD |
935 | ... |
936 | }; | |
5ba9f198 | 937 | |
fcba70d4 MD |
938 | variant name { |
939 | ... | |
940 | }; | |
941 | ||
cfc73fdc | 942 | enum name <integer_type or size> { |
3bf79539 MD |
943 | ... |
944 | }; | |
945 | ||
2152348f | 946 | |
4fa992a5 MD |
947 | /* |
948 | * Unnamed types, contained within compound type fields, typedef or typealias. | |
949 | */ | |
2152348f | 950 | |
80fd2569 MD |
951 | struct { |
952 | ... | |
2152348f | 953 | } |
5ba9f198 | 954 | |
fcba70d4 MD |
955 | variant { |
956 | ... | |
957 | } | |
958 | ||
4767a9e7 | 959 | enum <integer_type or size> { |
80fd2569 | 960 | ... |
2152348f MD |
961 | } |
962 | ||
963 | typedef type new_type[length]; | |
3bf79539 | 964 | |
2152348f MD |
965 | struct { |
966 | type field_name[length]; | |
967 | } | |
968 | ||
969 | typedef type new_type[length_type]; | |
970 | ||
971 | struct { | |
972 | type field_name[length_type]; | |
973 | } | |
974 | ||
975 | integer { | |
80fd2569 | 976 | ... |
2152348f | 977 | } |
3bf79539 | 978 | |
2152348f | 979 | floating_point { |
80fd2569 | 980 | ... |
2152348f MD |
981 | } |
982 | ||
983 | struct { | |
984 | integer_type field_name:size; /* GNU/C bitfield */ | |
985 | } | |
986 | ||
987 | struct { | |
988 | string field_name; | |
989 | } | |
3bf79539 | 990 | |
fcba70d4 | 991 | |
3bf79539 | 992 | A. Helper macros |
5ba9f198 MD |
993 | |
994 | The two following macros keep track of the size of a GNU/C structure without | |
995 | padding at the end by placing HEADER_END as the last field. A one byte end field | |
996 | is used for C90 compatibility (C99 flexible arrays could be used here). Note | |
997 | that this does not affect the effective structure size, which should always be | |
998 | calculated with the header_sizeof() helper. | |
999 | ||
1000 | #define HEADER_END char end_field | |
1001 | #define header_sizeof(type) offsetof(typeof(type), end_field) | |
3bf79539 MD |
1002 | |
1003 | ||
1004 | B. Stream Header Rationale | |
1005 | ||
1006 | An event stream is divided in contiguous event packets of variable size. These | |
1007 | subdivisions allow the trace analyzer to perform a fast binary search by time | |
1008 | within the stream (typically requiring to index only the event packet headers) | |
1009 | without reading the whole stream. These subdivisions have a variable size to | |
1010 | eliminate the need to transfer the event packet padding when partially filled | |
1011 | event packets must be sent when streaming a trace for live viewing/analysis. | |
1012 | An event packet can contain a certain amount of padding at the end. Dividing | |
1013 | streams into event packets is also useful for network streaming over UDP and | |
1014 | flight recorder mode tracing (a whole event packet can be swapped out of the | |
1015 | buffer atomically for reading). | |
1016 | ||
1017 | The stream header is repeated at the beginning of each event packet to allow | |
1018 | flexibility in terms of: | |
1019 | ||
1020 | - streaming support, | |
1021 | - allowing arbitrary buffers to be discarded without making the trace | |
1022 | unreadable, | |
1023 | - allow UDP packet loss handling by either dealing with missing event packet | |
1024 | or asking for re-transmission. | |
1025 | - transparently support flight recorder mode, | |
1026 | - transparently support crash dump. | |
1027 | ||
1028 | The event stream header will therefore be referred to as the "event packet | |
1029 | header" throughout the rest of this document. | |
fcba70d4 MD |
1030 | |
1031 | C. CTF Metadata Grammar | |
1032 | ||
4fa992a5 MD |
1033 | /* |
1034 | * Common Trace Format (CTF) Metadata Grammar. | |
1035 | * | |
1036 | * Inspired from the C99 grammar: | |
1037 | * http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf (Annex A) | |
1038 | * | |
1039 | * Specialized for CTF needs by including only constant and declarations from | |
1040 | * C99 (excluding function declarations), and by adding support for variants, | |
1041 | * sequences and CTF-specific specifiers. | |
1042 | */ | |
1043 | ||
1044 | 1) Lexical grammar | |
1045 | ||
1046 | 1.1) Lexical elements | |
1047 | ||
1048 | token: | |
1049 | keyword | |
1050 | identifier | |
1051 | constant | |
1052 | string-literal | |
1053 | punctuator | |
1054 | ||
1055 | 1.2) Keywords | |
1056 | ||
1057 | keyword: is one of | |
1058 | ||
1059 | const | |
1060 | char | |
1061 | double | |
1062 | enum | |
1063 | event | |
1064 | floating_point | |
1065 | float | |
1066 | integer | |
1067 | int | |
1068 | long | |
1069 | short | |
1070 | signed | |
1071 | stream | |
1072 | string | |
1073 | struct | |
1074 | trace | |
3e1e1a78 | 1075 | typealias |
4fa992a5 MD |
1076 | typedef |
1077 | unsigned | |
1078 | variant | |
1079 | void | |
1080 | _Bool | |
1081 | _Complex | |
1082 | _Imaginary | |
1083 | ||
1084 | ||
1085 | 1.3) Identifiers | |
1086 | ||
1087 | identifier: | |
1088 | identifier-nondigit | |
1089 | identifier identifier-nondigit | |
1090 | identifier digit | |
1091 | ||
1092 | identifier-nondigit: | |
1093 | nondigit | |
1094 | universal-character-name | |
1095 | any other implementation-defined characters | |
1096 | ||
1097 | nondigit: | |
1098 | _ | |
1099 | [a-zA-Z] /* regular expression */ | |
1100 | ||
1101 | digit: | |
1102 | [0-9] /* regular expression */ | |
1103 | ||
1104 | 1.4) Universal character names | |
1105 | ||
1106 | universal-character-name: | |
1107 | \u hex-quad | |
1108 | \U hex-quad hex-quad | |
1109 | ||
1110 | hex-quad: | |
1111 | hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit | |
1112 | ||
1113 | 1.5) Constants | |
1114 | ||
1115 | constant: | |
1116 | integer-constant | |
1117 | enumeration-constant | |
1118 | character-constant | |
1119 | ||
1120 | integer-constant: | |
1121 | decimal-constant integer-suffix-opt | |
1122 | octal-constant integer-suffix-opt | |
1123 | hexadecimal-constant integer-suffix-opt | |
1124 | ||
1125 | decimal-constant: | |
1126 | nonzero-digit | |
1127 | decimal-constant digit | |
1128 | ||
1129 | octal-constant: | |
1130 | 0 | |
1131 | octal-constant octal-digit | |
1132 | ||
1133 | hexadecimal-constant: | |
1134 | hexadecimal-prefix hexadecimal-digit | |
1135 | hexadecimal-constant hexadecimal-digit | |
1136 | ||
1137 | hexadecimal-prefix: | |
1138 | 0x | |
1139 | 0X | |
1140 | ||
1141 | nonzero-digit: | |
1142 | [1-9] | |
1143 | ||
1144 | integer-suffix: | |
1145 | unsigned-suffix long-suffix-opt | |
1146 | unsigned-suffix long-long-suffix | |
1147 | long-suffix unsigned-suffix-opt | |
1148 | long-long-suffix unsigned-suffix-opt | |
1149 | ||
1150 | unsigned-suffix: | |
1151 | u | |
1152 | U | |
1153 | ||
1154 | long-suffix: | |
1155 | l | |
1156 | L | |
1157 | ||
1158 | long-long-suffix: | |
1159 | ll | |
1160 | LL | |
1161 | ||
1162 | digit-sequence: | |
1163 | digit | |
1164 | digit-sequence digit | |
1165 | ||
1166 | hexadecimal-digit-sequence: | |
1167 | hexadecimal-digit | |
1168 | hexadecimal-digit-sequence hexadecimal-digit | |
1169 | ||
1170 | enumeration-constant: | |
1171 | identifier | |
1172 | string-literal | |
1173 | ||
1174 | character-constant: | |
1175 | ' c-char-sequence ' | |
1176 | L' c-char-sequence ' | |
1177 | ||
1178 | c-char-sequence: | |
1179 | c-char | |
1180 | c-char-sequence c-char | |
1181 | ||
1182 | c-char: | |
1183 | any member of source charset except single-quote ('), backslash | |
1184 | (\), or new-line character. | |
1185 | escape-sequence | |
1186 | ||
1187 | escape-sequence: | |
1188 | simple-escape-sequence | |
1189 | octal-escape-sequence | |
1190 | hexadecimal-escape-sequence | |
1191 | universal-character-name | |
1192 | ||
1193 | simple-escape-sequence: one of | |
1194 | \' \" \? \\ \a \b \f \n \r \t \v | |
1195 | ||
1196 | octal-escape-sequence: | |
1197 | \ octal-digit | |
1198 | \ octal-digit octal-digit | |
1199 | \ octal-digit octal-digit octal-digit | |
1200 | ||
1201 | hexadecimal-escape-sequence: | |
1202 | \x hexadecimal-digit | |
1203 | hexadecimal-escape-sequence hexadecimal-digit | |
1204 | ||
1205 | 1.6) String literals | |
1206 | ||
1207 | string-literal: | |
1208 | " s-char-sequence-opt " | |
1209 | L" s-char-sequence-opt " | |
1210 | ||
1211 | s-char-sequence: | |
1212 | s-char | |
1213 | s-char-sequence s-char | |
1214 | ||
1215 | s-char: | |
1216 | any member of source charset except double-quote ("), backslash | |
1217 | (\), or new-line character. | |
1218 | escape-sequence | |
1219 | ||
1220 | 1.7) Punctuators | |
1221 | ||
1222 | punctuator: one of | |
1223 | [ ] ( ) { } . -> * + - < > : ; ... = , | |
1224 | ||
1225 | ||
1226 | 2) Phrase structure grammar | |
1227 | ||
1228 | primary-expression: | |
1229 | identifier | |
1230 | constant | |
1231 | string-literal | |
1232 | ( unary-expression ) | |
1233 | ||
1234 | postfix-expression: | |
1235 | primary-expression | |
1236 | postfix-expression [ unary-expression ] | |
1237 | postfix-expression . identifier | |
1238 | postfix-expressoin -> identifier | |
1239 | ||
1240 | unary-expression: | |
1241 | postfix-expression | |
1242 | unary-operator postfix-expression | |
1243 | ||
1244 | unary-operator: one of | |
1245 | + - | |
1246 | ||
4fa992a5 MD |
1247 | assignment-operator: |
1248 | = | |
1249 | ||
1250 | constant-expression: | |
1251 | unary-expression | |
1252 | ||
1253 | constant-expression-range: | |
1254 | constant-expression ... constant-expression | |
1255 | ||
1256 | 2.2) Declarations: | |
1257 | ||
1258 | declaration: | |
3b0f8e4d MD |
1259 | declaration-specifiers ; |
1260 | declaration-specifiers storage-class-specifier declaration-specifiers declarator-list ; | |
4fa992a5 MD |
1261 | ctf-specifier ; |
1262 | ||
1263 | declaration-specifiers: | |
4fa992a5 MD |
1264 | type-specifier declaration-specifiers-opt |
1265 | type-qualifier declaration-specifiers-opt | |
1266 | ||
1267 | declarator-list: | |
1268 | declarator | |
1269 | declarator-list , declarator | |
1270 | ||
d285084f MD |
1271 | abstract-declarator-list: |
1272 | abstract-declarator | |
1273 | abstract-declarator-list , abstract-declarator | |
1274 | ||
4fa992a5 MD |
1275 | storage-class-specifier: |
1276 | typedef | |
1277 | ||
1278 | type-specifier: | |
1279 | void | |
1280 | char | |
1281 | short | |
1282 | int | |
1283 | long | |
1284 | float | |
1285 | double | |
1286 | signed | |
1287 | unsigned | |
1288 | _Bool | |
1289 | _Complex | |
9dfcfc0f MD |
1290 | struct-specifier |
1291 | variant-specifier | |
4fa992a5 MD |
1292 | enum-specifier |
1293 | typedef-name | |
1294 | ctf-type-specifier | |
1295 | ||
1296 | struct-specifier: | |
3b0f8e4d | 1297 | struct identifier-opt { struct-or-variant-declaration-list-opt } |
4fa992a5 MD |
1298 | struct identifier |
1299 | ||
1300 | struct-or-variant-declaration-list: | |
1301 | struct-or-variant-declaration | |
1302 | struct-or-variant-declaration-list struct-or-variant-declaration | |
1303 | ||
1304 | struct-or-variant-declaration: | |
1305 | specifier-qualifier-list struct-or-variant-declarator-list ; | |
550aca33 | 1306 | declaration-specifiers storage-class-specifier declaration-specifiers declarator-list ; |
d285084f MD |
1307 | typealias declaration-specifiers abstract-declarator-list : declaration-specifiers abstract-declarator-list ; |
1308 | typealias declaration-specifiers abstract-declarator-list : declarator-list ; | |
4fa992a5 MD |
1309 | |
1310 | specifier-qualifier-list: | |
1311 | type-specifier specifier-qualifier-list-opt | |
1312 | type-qualifier specifier-qualifier-list-opt | |
1313 | ||
1314 | struct-or-variant-declarator-list: | |
1315 | struct-or-variant-declarator | |
1316 | struct-or-variant-declarator-list , struct-or-variant-declarator | |
1317 | ||
1318 | struct-or-variant-declarator: | |
1319 | declarator | |
1320 | declarator-opt : constant-expression | |
1321 | ||
1322 | variant-specifier: | |
1323 | variant identifier-opt variant-tag-opt { struct-or-variant-declaration-list } | |
1324 | variant identifier variant-tag | |
1325 | ||
1326 | variant-tag: | |
1327 | < identifier > | |
1328 | ||
1329 | enum-specifier: | |
1330 | enum identifier-opt { enumerator-list } | |
1331 | enum identifier-opt { enumerator-list , } | |
1332 | enum identifier | |
359894ac MD |
1333 | enum identifier-opt < declaration-specifiers > { enumerator-list } |
1334 | enum identifier-opt < declaration-specifiers > { enumerator-list , } | |
1335 | enum identifier < declaration-specifiers > | |
4fa992a5 MD |
1336 | enum identifier-opt < integer-constant > { enumerator-list } |
1337 | enum identifier-opt < integer-constant > { enumerator-list , } | |
1338 | enum identifier < integer-constant > | |
1339 | ||
1340 | enumerator-list: | |
1341 | enumerator | |
1342 | enumerator-list , enumerator | |
1343 | ||
1344 | enumerator: | |
1345 | enumeration-constant | |
1346 | enumeration-constant = constant-expression | |
1347 | enumeration-constant = constant-expression-range | |
1348 | ||
1349 | type-qualifier: | |
1350 | const | |
1351 | ||
1352 | declarator: | |
1353 | pointer-opt direct-declarator | |
1354 | ||
1355 | direct-declarator: | |
1356 | identifier | |
1357 | ( declarator ) | |
1358 | direct-declarator [ type-specifier ] | |
1359 | direct-declarator [ constant-expression ] | |
1360 | ||
d285084f MD |
1361 | abstract-declarator: |
1362 | pointer-opt direct-abstract-declarator | |
1363 | ||
1364 | direct-abstract-declarator: | |
1365 | identifier-opt | |
1366 | ( abstract-declarator ) | |
1367 | direct-abstract-declarator [ type-specifier ] | |
1368 | direct-abstract-declarator [ constant-expression ] | |
1369 | direct-abstract-declarator [ ] | |
1370 | ||
4fa992a5 | 1371 | pointer: |
3b0f8e4d MD |
1372 | * type-qualifier-list-opt |
1373 | * type-qualifier-list-opt pointer | |
4fa992a5 MD |
1374 | |
1375 | type-qualifier-list: | |
1376 | type-qualifier | |
1377 | type-qualifier-list type-qualifier | |
1378 | ||
4fa992a5 MD |
1379 | typedef-name: |
1380 | identifier | |
1381 | ||
1382 | 2.3) CTF-specific declarations | |
1383 | ||
1384 | ctf-specifier: | |
1385 | event { ctf-assignment-expression-list-opt } | |
1386 | stream { ctf-assignment-expression-list-opt } | |
1387 | trace { ctf-assignment-expression-list-opt } | |
d285084f MD |
1388 | typealias declaration-specifiers abstract-declarator-list : declaration-specifiers abstract-declarator-list ; |
1389 | typealias declaration-specifiers abstract-declarator-list : declarator-list ; | |
4fa992a5 MD |
1390 | |
1391 | ctf-type-specifier: | |
1392 | floating_point { ctf-assignment-expression-list-opt } | |
1393 | integer { ctf-assignment-expression-list-opt } | |
1394 | string { ctf-assignment-expression-list-opt } | |
1395 | ||
1396 | ctf-assignment-expression-list: | |
1397 | ctf-assignment-expression | |
1398 | ctf-assignment-expression-list ; ctf-assignment-expression | |
1399 | ||
1400 | ctf-assignment-expression: | |
1401 | unary-expression assignment-operator unary-expression | |
1402 | unary-expression type-assignment-operator type-specifier | |
550aca33 | 1403 | declaration-specifiers storage-class-specifier declaration-specifiers declarator-list |
d285084f MD |
1404 | typealias declaration-specifiers abstract-declarator-list : declaration-specifiers abstract-declarator-list |
1405 | typealias declaration-specifiers abstract-declarator-list : declarator-list |