High level conclusions

Fuzzers reach 51.88% code coverage.

Fuzzer fuzz_lib2to3_parse is blocked:

The runtime code coverage of fuzz_lib2to3_parse covers 0.0% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Reachability and coverage overview

Functions statically reachable by fuzzers

72 / 318

Cyclomatic complexity statically reachable by fuzzers

341 / 1300

Runtime code coverage of functions

165 / 318

Warning: The number of runtime covered functions are larger than the number of reachable functions. This means that Fuzz Introspector found there are more functions covered at runtime than what is considered reachable based on the static analysis. This is a limitation in the analysis as anything covered at runtime is by definition reachable by the fuzzers.
This is likely due to a limitation in the static analysis. In this case, the count of functions covered at runtime is the true value, which means this is what should be considered "achieved" by the fuzzer.

Use the project functions table below to query all functions that were not covered at runtime.

The following table shows data about each function in the project. The functions included in this table correspond to all functions that exist in the executables of the fuzzers. As such, there may be functions that are from third-party libraries.

For further technical details on the meaning of columns in the below table, please see the Glossary .

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

Fuzzer: fuzz_lib2to3_parse

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	4	100.%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	0	0.0%
All colors	4	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
3	0	EP	call site: 00000	atheris.FuzzedDataProvider

Runtime coverage analysis

Covered functions

217

Functions that are reachable but not covered

4

Reachable functions

4

Percentage of reachable functions covered

0.0%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/	1
...fuzz_lib2to3_parse	3

Fuzzer: fuzz_format_filecontents

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	192	50.3%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	189	49.6%
All colors	381	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
50	0	EP	call site: 00000	black.format_file_contents
28	146	black.nodes.preceding_leaf	call site: 00146	black.comments.generate_ignored_nodes
14	363	black.assert_stable	call site: 00363	black.handle_ipynb_magics.put_trailing_semicolon_back
11	99	black.get_features_used	call site: 00099	black.nodes.is_simple_decorator_expression
11	211	black.lines.is_line_short_enough	call site: 00211	black.nodes.is_multiline_string
7	72	black.get_future_imports	call site: 00072	black.get_future_imports.get_imports_from_children
7	224	black.strings.has_triple_quotes	call site: 00224	.len
7	309	black.parsing.parse_single_version	call site: 00309	typed_ast.ast3.parse
6	58	black.mode.supports_feature	call site: 00058	black.mode.supports_feature
6	116	black.get_features_used	call site: 00116	.len
5	195	black.lines.EmptyLineTracker._maybe_empty_lines	call site: 00195	black.lines.EmptyLineTracker._maybe_empty_lines_for_class_or_def
4	124	black.get_features_used	call site: 00124	black.mode.supports_feature

Runtime coverage analysis

Covered functions

217

Functions that are reachable but not covered

131

Reachable functions

191

Percentage of reachable functions covered

31.41%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/	1
...fuzz_format_filecontents	5
black	59
black.handle_ipynb_magics	24
black.parsing	26
black.mode	1
black.trans	3
black.nodes	16
black.comments	30
black.linegen	20
black.lines	37
black.strings	1
black.output	6

Fuzzer: fuzz_raw_format_filecontents

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	191	50.2%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	189	49.7%
All colors	380	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
50	0	EP	call site: 00000	black.format_file_contents
28	146	black.nodes.preceding_leaf	call site: 00146	black.comments.generate_ignored_nodes
14	363	black.assert_stable	call site: 00363	black.handle_ipynb_magics.put_trailing_semicolon_back
11	99	black.get_features_used	call site: 00099	black.nodes.is_simple_decorator_expression
11	211	black.lines.is_line_short_enough	call site: 00211	black.nodes.is_multiline_string
7	72	black.get_future_imports	call site: 00072	black.get_future_imports.get_imports_from_children
7	224	black.strings.has_triple_quotes	call site: 00224	.len
7	309	black.parsing.parse_single_version	call site: 00309	ast.parse
6	58	black.mode.supports_feature	call site: 00058	black.mode.supports_feature
6	116	black.get_features_used	call site: 00116	.len
5	195	black.lines.EmptyLineTracker._maybe_empty_lines	call site: 00195	black.lines.EmptyLineTracker._maybe_empty_lines_for_class_or_def
4	124	black.get_features_used	call site: 00124	black.mode.supports_feature

Runtime coverage analysis

Covered functions

217

Functions that are reachable but not covered

129

Reachable functions

189

Percentage of reachable functions covered

31.75%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/	1
...fuzz_raw_format_filecontents	4
black	59
black.handle_ipynb_magics	24
black.parsing	26
black.mode	1
black.trans	3
black.nodes	16
black.comments	30
black.linegen	20
black.lines	37
black.strings	1
black.output	6

Optimal target analysis

Remaining optimal interesting functions

The following table shows a list of functions that are optimal targets. Optimal targets are identified by finding the functions that in combination, yield a high code coverage.

Func name	Functions filename	Arg count	Args	Function depth	hitcount	instr count	bb count	cyclomatic complexity	Reachable functions	Incoming references	total cyclomatic complexity	Unreached complexity
black.main	black	27	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	6	0	25	17	10	324	3	1142	458
black.trans.StringTransformer.__call__	black.trans	4	['N/A', 'N/A', 'N/A', 'N/A']	5	0	2	3	4	145	0	525	336
black.linegen.LineGenerator.visit_power	black.linegen	2	['N/A', 'N/A']	3	0	3	2	4	100	0	384	179
black.linegen._maybe_split_omitting_optional_parens	black.linegen	5	['N/A', 'N/A', 'N/A', 'N/A', 'N/A']	4	0	4	5	5	78	3	313	126
black.read_pyproject_toml	black	3	['N/A', 'N/A', 'N/A']	3	0	3	5	5	47	0	153	81
black.trans.BaseStringSplitter.do_match	black.trans	2	['N/A', 'N/A']	2	0	0	2	4	45	0	165	62
black.linegen.LineGenerator.visit_STRING	black.linegen	2	['N/A', 'N/A']	3	0	2	12	8	90	0	342	49
black.linegen.normalize_invisible_parens	black.linegen	4	['N/A', 'N/A', 'N/A', 'N/A']	3	0	9	14	9	55	3	208	41

Implementing fuzzers that target the above functions will improve reachability such that it becomes:

Functions statically reachable by fuzzers

228 / 318

Cyclomatic complexity statically reachable by fuzzers

990 / 1300

All functions overview

If you implement fuzzers for these functions, the status of all functions in the project will be:

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

This section shows analysis of runtime coverage data.

For futher technical details on how this section is generated, please see the Glossary .

Complex functions with low coverage

Func name	Function total lines	Lines covered at runtime	percentage covered	Reached by fuzzers
black.main	59	0	0.0%	[]
black.get_sources	37	0	0.0%	[]
black.reformat_one	31	0	0.0%	[]
black.format_file_in_place	36	0	0.0%	[]
re.split	1155	342	29.61%	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']
black.comments.convert_one_fmt_off_pair	42	7	16.66%	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']
black.lines.EmptyLineTracker._maybe_empty_lines	37	17	45.94%	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']
black.lines.EmptyLineTracker._maybe_empty_lines_for_class_or_def	39	0	0.0%	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']
black.lines.is_line_short_enough	47	5	10.63%	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']
blib2to3.pytree.Node.splitlines	476	242	50.84%	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']
black.trans.StringMerger._merge_one_string_group.make_naked	52	0	0.0%	[]
black.trans.StringMerger._validate_msg	38	2	5.263%	[]
black.trans.StringParenStripper.do_match	33	0	0.0%	[]
black.trans.BaseStringSplitter._get_max_string_length	39	0	0.0%	[]
black.trans.StringSplitter.do_transform.more_splits_should_be_made	60	0	0.0%	[]
black.trans.StringParenWrapper.do_transform	74	12	16.21%	[]
match.group	162	29	17.90%	[]
os.cpu_count	53	9	16.98%	[]
pathspec.PathSpec.from_lines	68	26	38.23%	[]
i.strip	196	41	20.91%	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']
packaging.version.Version	165	67	40.60%	[]
packaging.specifiers.Specifier	256	83	32.42%	[]
pattern.search	54	25	46.29%	[]

This section shows which files and directories are considered in this report. The main reason for showing this is fuzz introspector may include more code in the reasoning than is desired. This section helps identify if too many files/directories are included, e.g. third party code, which may be irrelevant for the threat model. In the event too much is included, fuzz introspector supports a configuration file that can exclude data from the report. See the following link for more information on how to create a config file: link

Files in report

Source file	Reached by	Covered by
	[]	[]
black.nodes	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
tokenize_rt	[]	[]
black.strings	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
tomllib	[]	[]
typing	[]	[]
tempfile	[]	[]
traceback	[]	[]
blib2to3	[]	[]
os	[]	[]
dataclasses	[]	[]
warnings	[]	[]
black.concurrency	[]	[]
black.output	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
asyncio	[]	[]
black.rusty	[]	[]
black.report	[]	[]
black.numerics	[]	[]
ast	[]	[]
functools	[]	[]
black.const	[]	[]
...fuzz_format_filecontents	['fuzz_format_filecontents']	[]
black.handle_ipynb_magics	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
datetime	[]	[]
sys	[]	[]
black.lines	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
pickle	[]	[]
uvloop	[]	[]
black.brackets	[]	[]
pathlib	[]	[]
...fuzz_raw_format_filecontents	['fuzz_raw_format_filecontents']	[]
concurrent	[]	[]
platform	[]	[]
click	[]	[]
hashlib	[]	[]
re	[]	[]
	[]	[]
mypy_extensions	[]	[]
json	[]	[]
secrets	[]	[]
packaging	[]	[]
tomli	[]	[]
IPython	[]	[]
black.mode	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
black.comments	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
...fuzz_lib2to3_parse	['fuzz_lib2to3_parse']	[]
black.trans	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
typed_ast	[]	[]
black.__main__	[]	[]
itertools	[]	[]
black.files	[]	[]
io	[]	[]
black.debug	[]	[]
black	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
operator	[]	[]
black.linegen	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
logging	[]	[]
platformdirs	[]	[]
black.cache	[]	[]
collections	[]	[]
enum	[]	[]
multiprocessing	[]	[]
pathspec	[]	[]
_black_version	[]	[]
atheris	[]	[]
tokenize	[]	[]
black.parsing	['fuzz_format_filecontents', 'fuzz_raw_format_filecontents']	[]
black._width_table	[]	[]
difflib	[]	[]
colorama	[]	[]

Directories in report

Directory