objects.md

Objects internal structure

Each structure consists of 32-bit unsigned int numbers. They are stored and loaded in memory order, which means they follow current architecture endiannes. In tables below, each offset and size is in 4-byte increments (so offset 10 means 40 bytes from beginning of the file).

After un-gzipping, each file start with a file header, consisting of magic and version.

Types

Type	Description
uint	32-bit integer without a sign. E.g. uint32_t.
magic	uint with recognizable mnemonic.
version	uint with major in upper 16 bits and minor in lower 16 bits. Currently, only version 1.0 (or 0x0001'00000) is defined, but changes to minor must be backwards compatible.
str	uint referencing into file's string block
oid	20 byte (4 uint) SHA256 reference to another object.
timestamp	uint64 number of seconds since UNIX epoch; when looking at it as a pair of uints, first will contain upper 32bits and second - lower 32 bits of timestamp.
UTF8Z	Block of ASCIIZ-like strings. Like ASCIIZ, each string ends with a byte zero, unlike ASCIIZ, each string is encoded with UTF-8.

Common structures

block

Offset	Size	Value	Ref	Type
0	1	offset	SO	uint
1	1	size	SIZE	uint

array_ref

Offset	Size	Value	Ref	Type
0	1	offset	EO	uint
2	1	size	ES	uint
3	1	count	EC	uint

stats

Offset	Size	Value	Type
0	1	total	uint
1	1	visited	uint

REPORT

Offset	Size	Value	Type
			file header
0	1	"rprt"	magic
1	1	1.0	version
			header
2	2	strings	block
4	5	parent	oid
4	5	file_list	oid
9	3	builds	array_ref
12	2	added	timestamp
		git	report::commit
14	1	branch	str
15	2	author	email_ref
17	2	committer	email_ref
19	1	message	str
20	5	commit_id	oid
25	2	committed	timestamp
		stats	coverage_stats
27	1	lines_total	uint
28	2	lines	stats
30	2	functions	stats
32	2	branches	stats
SO	SIZE	bytes	UTF8Z
EO	ES×EC	entries	report_set_entry[EC]

report::build

Offset	Size	Value	Type
0	5	build	oid
5	1	propset	str
		set	coverage_stats
6	1	lines_total	uint
7	2	lines	stats
9	2	functions	stats
11	2	branches	stats

email_ref

Offset	Size	Value	Type
0	1	name	str
1	1	email	str

BUILD

Offset	Size	Value	Type
			file header
0	1	"bld "	magic
1	1	1.0	version
			report_header
2	1	strings	block
3	5	file list	oid
8	2	added	timestamp
10	1	propset	str
			coverage_stats
11	1	lines_total	uint
12	2	lines	stats
14	2	functions	stats
16	2	branches	stats
			strings
SO	SIZE	bytes	UTF8Z

FILES

Offset	Size	Value	Type
			file header
0	1	"list"	magic
1	1	1.0	version
			files
2	2	strings	block
4	3	entries	array_ref
SO	SIZE	bytes	UTF8Z
EO	ES×EC	entries	files::entry[EC]

report_entry_stats

Offset	Size	Value	Type
0	2	summary	stats
2	5	details	oid

files::entry

Report entry has variadic length. For reports, where no file has reported function or branch coverage, the EC will be 14 uints. If at least one file has function or branch coverage, EC will be 28 uints.

EC == 14, files::basic

Offset	Size	Value	Type
0	1	path	str
1	5	contents	oid
6	1	lines_total	uint
7	7	lines	report_entry_stats

EC > 14, files::ext

Offset	Size	Value	Type
14	7	functions	report_entry_stats
21	7	branches	report_entry_stats

LINE COVERAGE

Offset	Size	Value	Ref	Type
				file header
0	1	"lnes"		magic
1	1	1.0		version
				line_coverage
2	1	line_count	LC	uint
3	LC	coverage		uint

coverage

To get the line number, start with 1. Then, if flag is set, add value to the line number, otherwise increment line number by 1. If flag is cleared, value is execution count for current line.

Bit from	Bit to	Value	Type
31	31	is_null	flag
30	0	value	uint

FUNCTION COVERAGE

Offset	Size	Value	Type
			file header
0	1	"fnct"	magic
1	1	1.0	version
			function_coverage
2	2	strings	block
4	3	entries	array_ref
SO	SIZE	bytes	UTF8Z
EO	ES×EC	entries	function_coverage_entry[EC]

function_coverage_entry

For each line or column number, 0 denotes that value is missing. Also, a missing demangled name would point to a string of length 0.

Offset	Size	Value	Type
0	1	name	str
1	1	demangled_name	str
2	1	count	uint
3	1	line_start	uint
4	1	column_start	uint
5	1	line_end	uint
6	1	column_end	uint