Fuzz introspector
For issues and ideas: https://github.com/ossf/fuzz-introspector/issues
Report generation date: 2026-10-17

Project overview: pest

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
0.0%
1 / 951
Cyclomatic complexity statically reachable by fuzzers
0.0%
1 / 907
Runtime code coverage of functions
17.0%
163 / 951

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.

Project functions overview

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 Runtime reached by Fuzzers Combined 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 details

Fuzzer: http

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 70 100.%
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 70 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
69 0 EP call site: 00000

Runtime coverage analysis

Covered functions
143
Functions that are reachable but not covered
3
Reachable functions
3
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
grammars/fuzz/fuzz_targets/http.rs 3

Fuzzer: json

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 0 705 89.2%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 85 10.7%
All colors 790 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
205 415 visualize_whitespace call site: 00415 StackAnalysis::steps
132 168 ParserState::match_string call site: 00168 StackAnalysis::repeat
106 6 pest::set_call_limit call site: 00006 TestParser::parse
61 306 ParserState::match_string call site: 00306 ParserState::stack_pop
36 732 CallLimitTracker::limit_reached call site: 00732 bool
22 629 Stack::clear_snapshot call site: 00629 ExprTopDownIterator::next
21 119 ParserState::match_string call site: 00119 Stack::clear_snapshot
19 770 pest::set_call_limit call site: 00770 object
17 714 ParserState::inc_call_check_limit call site: 00714 test_call_limit_small_budget
14 683 ParserState::match_string call site: 00683 StackAnalysis::repeat
13 371 Position::line_col call site: 00371 pop
12 150 Stack::clear_snapshot call site: 00150 ParseAttempts::try_add_new_token

Runtime coverage analysis

Covered functions
133
Functions that are reachable but not covered
6
Reachable functions
7
Percentage of reachable functions covered
14.29%
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
grammars/fuzz/fuzz_targets/json.rs 7
pest/src/parser_state.rs 40
grammars/benches/json.rs 10
meta/src/grammar.rs 19
meta/src/optimizer/restorer.rs 6
meta/src/ast.rs 26
meta/fuzz/fuzz_targets/parser.rs 3
pest/src/iterators/pair.rs 3
meta/src/parser.rs 43
pest/src/macros.rs 8
pest/tests/depth_limit.rs 11
pest/src/stack.rs 11
meta/src/validator/stack_loops.rs 42
meta/src/validator.rs 9
meta/src/lib.rs 7
pest/src/error.rs 19
pest/src/span.rs 9
pest/src/position.rs 7
pest/src/iterators/pairs.rs 1
pest/tests/json.rs 13

Fuzzer: toml

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 0 757 89.9%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 85 10.0%
All colors 842 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
205 415 visualize_whitespace call site: 00415 StackAnalysis::steps
132 168 ParserState::match_string call site: 00168 StackAnalysis::repeat
106 6 pest::set_call_limit call site: 00006 TestParser::parse
71 770 pest::set_call_limit call site: 00770
61 306 ParserState::match_string call site: 00306 ParserState::stack_pop
36 732 CallLimitTracker::limit_reached call site: 00732 bool
22 629 Stack::clear_snapshot call site: 00629 ExprTopDownIterator::next
21 119 ParserState::match_string call site: 00119 Stack::clear_snapshot
17 714 ParserState::inc_call_check_limit call site: 00714 test_call_limit_small_budget
14 683 ParserState::match_string call site: 00683 StackAnalysis::repeat
13 371 Position::line_col call site: 00371 pop
12 150 Stack::clear_snapshot call site: 00150 ParseAttempts::try_add_new_token

Runtime coverage analysis

Covered functions
315
Functions that are reachable but not covered
6
Reachable functions
7
Percentage of reachable functions covered
14.29%
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
grammars/fuzz/fuzz_targets/toml.rs 7
pest/src/parser_state.rs 40
grammars/benches/json.rs 10
meta/src/grammar.rs 19
meta/src/optimizer/restorer.rs 6
meta/src/ast.rs 26
meta/fuzz/fuzz_targets/parser.rs 3
pest/src/iterators/pair.rs 3
meta/src/parser.rs 43
pest/src/macros.rs 8
pest/tests/depth_limit.rs 11
pest/src/stack.rs 11
meta/src/validator/stack_loops.rs 42
meta/src/validator.rs 9
meta/src/lib.rs 7
pest/src/error.rs 19
pest/src/span.rs 9
pest/src/position.rs 7
pest/src/iterators/pairs.rs 1
pest/tests/json.rs 13

Fuzzer: sql

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 70 100.%
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 70 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
69 0 EP call site: 00000

Runtime coverage analysis

Covered functions
1140
Functions that are reachable but not covered
2
Reachable functions
3
Percentage of reachable functions covered
33.33%
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
grammars/fuzz/fuzz_targets/sql.rs 3

Fuzzer: parser

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 0 729 89.5%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 85 10.4%
All colors 814 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
199 6 pest::set_call_limit call site: 00006 J::s::o::n::P::a::r::s::e::r::::::::p::a::r::s::e::value
136 600 visualize_whitespace call site: 00600 StackAnalysis::steps
132 366 ParserState::match_string call site: 00366 StackAnalysis::repeat
61 504 ParserState::match_string call site: 00504 ParserState::stack_pop
41 261 ParserState::match_string call site: 00261 ExprTopDownIterator::next
36 771 CallLimitTracker::limit_reached call site: 00771 bool
22 311 Stack::clear_snapshot call site: 00311 ExprTopDownIterator::next
21 212 ParserState::match_string call site: 00212 Stack::clear_snapshot
17 753 ParserState::inc_call_check_limit call site: 00753 tests::lines_eof
12 243 Stack::clear_snapshot call site: 00243 ParseAttempts::try_add_new_token
11 586 position::Position::line_col call site: 00586 ExprTopDownIterator::next
6 354 ParserState::match_range call site: 00354 number

Runtime coverage analysis

Covered functions
708
Functions that are reachable but not covered
5
Reachable functions
7
Percentage of reachable functions covered
28.57%
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
meta/fuzz/fuzz_targets/parser.rs 7
pest/src/parser_state.rs 40
grammars/benches/json.rs 10
meta/src/grammar.rs 15
meta/src/optimizer/restorer.rs 6
meta/src/ast.rs 22
pest/tests/json.rs 13
meta/src/parser.rs 43
pest/src/macros.rs 8
pest/src/stack.rs 11
pest/tests/depth_limit.rs 1
meta/src/validator/stack_loops.rs 42
meta/src/validator.rs 9
meta/src/lib.rs 7
pest/src/error.rs 19
pest/src/span.rs 9
pest/src/position.rs 7
pest/src/iterators/pair.rs 3
pest/src/iterators/pairs.rs 1

Fuzz engine guidance

This sections provides heuristics that can be used as input to a fuzz engine when running a given fuzz target. The current focus is on providing input that is usable by libFuzzer.

grammars/fuzz/fuzz_targets/http.rs

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


grammars/fuzz/fuzz_targets/json.rs

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['visualize_whitespace', 'ParserState::match_string', 'pest::set_call_limit', 'CallLimitTracker::limit_reached', 'Stack::clear_snapshot', 'ParserState::inc_call_check_limit']

grammars/fuzz/fuzz_targets/toml.rs

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['visualize_whitespace', 'ParserState::match_string', 'pest::set_call_limit', 'CallLimitTracker::limit_reached', 'Stack::clear_snapshot', 'ParserState::inc_call_check_limit']

grammars/fuzz/fuzz_targets/sql.rs

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


meta/fuzz/fuzz_targets/parser.rs

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['pest::set_call_limit', 'visualize_whitespace', 'ParserState::match_string', 'CallLimitTracker::limit_reached', 'Stack::clear_snapshot', 'ParserState::inc_call_check_limit']

Files and Directories in report

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
/src/pest/derive/tests/grammar_inline.rs [] []
/src/pest/meta/src/validator.rs ['json', 'toml', 'parser'] []
/src/pest/pest/benches/stack.rs [] []
/src/pest/pest/src/stack.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/vm/src/macros.rs [] []
/src/pest/pest/src/unicode/mod.rs [] []
/src/pest/derive/tests/grammar.rs [] []
/src/pest/pest/src/iterators/pairs.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/grammars/fuzz/fuzz_targets/json.rs ['json'] []
/src/pest/meta/src/ast.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/meta/src/optimizer/lister.rs [] []
/src/pest/derive/tests/surround.rs [] []
/src/pest/pest/tests/depth_limit.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/vm/tests/grammar.rs [] []
/src/pest/derive/tests/nested_expr.rs [] []
/src/pest/pest/src/iterators/pair.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/vm/tests/surround.rs [] []
/src/pest/meta/src/validator/stack_loops.rs ['json', 'toml', 'parser'] ['toml', 'parser']
/src/pest/meta/src/optimizer/factorizer.rs [] []
/src/pest/pest/examples/parens.rs [] []
/src/pest/pest/src/prec_climber.rs [] []
/src/pest/pest/src/pratt_parser.rs [] []
/src/pest/grammars/benches/http.rs [] []
/src/pest/pest/src/iterators/flat_pairs.rs [] []
/src/pest/derive/tests/reporting.rs [] []
/src/pest/derive/tests/lists.rs [] []
/src/pest/derive/tests/oneormore.rs [] []
/src/pest/derive/tests/implicit.rs [] []
/src/pest/meta/src/optimizer/restorer.rs ['json', 'toml', 'parser'] []
/src/pest/grammars/tests/toml.rs [] []
/src/pest/meta/src/parser.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/pest/src/iterators/pairs_builder.rs [] []
/src/pest/generator/src/generator.rs [] []
/src/pest/grammars/fuzz/fuzz_targets/toml.rs ['toml'] []
/src/pest/pest/benches/pratt.rs [] []
/src/pest/grammars/fuzz/fuzz_targets/http.rs ['http'] []
/src/pest/pest/src/iterators/line_index.rs [] []
/src/pest/derive/tests/opt.rs [] []
/src/pest/derive/examples/calc.rs [] []
/src/pest/meta/fuzz/fuzz_targets/parser.rs ['json', 'toml', 'parser'] []
/src/pest/generator/src/lib.rs [] []
/src/pest/meta/src/optimizer/unroller.rs [] []
/src/pest/meta/src/lib.rs ['json', 'toml', 'parser'] []
/src/pest/grammars/tests/sql.rs [] []
/src/pest/pest/src/error.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/grammars/tests/json.rs [] []
/src/pest/debugger/src/lib.rs [] []
/src/pest/pest/src/span.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/vm/tests/lists.rs [] []
/src/pest/grammars/benches/json.rs ['json', 'toml', 'parser'] []
/src/pest/pest/src/iterators/tokens.rs [] []
/src/pest/pest/tests/calculator.rs [] []
/src/pest/pest/src/position.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/debugger/src/main.rs [] []
/src/pest/grammars/tests/http.rs [] []
/src/pest/grammars/src/lib.rs [] []
/src/pest/vm/src/lib.rs [] []
/src/pest/meta/src/optimizer/rotator.rs [] []
/src/pest/generator/src/docs.rs [] []
/src/pest/meta/src/grammar.rs ['json', 'toml', 'parser'] ['parser']
/src/pest/meta/src/optimizer/skipper.rs [] []
/src/pest/generator/src/macros.rs [] []
/src/pest/grammars/fuzz/fuzz_targets/sql.rs ['sql'] []
/src/pest/pest/src/macros.rs ['json', 'toml', 'parser'] []
/src/pest/generator/src/parse_derive.rs [] []
/src/pest/pest/tests/json.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']
/src/pest/meta/src/optimizer/concatenator.rs [] []
/src/pest/meta/src/optimizer/mod.rs [] []
/src/pest/pest/src/parser_state.rs ['json', 'toml', 'parser'] ['json', 'toml', 'parser']

Directories in report

Directory
/src/pest/vm/tests/
/src/pest/grammars/src/
/src/pest/pest/examples/
/src/pest/pest/src/unicode/
/src/pest/derive/examples/
/src/pest/vm/src/
/src/pest/pest/src/
/src/pest/generator/src/
/src/pest/meta/src/validator/
/src/pest/pest/src/iterators/
/src/pest/meta/fuzz/fuzz_targets/
/src/pest/grammars/benches/
/src/pest/meta/src/
/src/pest/pest/benches/
/src/pest/derive/tests/
/src/pest/grammars/fuzz/fuzz_targets/
/src/pest/grammars/tests/
/src/pest/debugger/src/
/src/pest/meta/src/optimizer/
/src/pest/pest/tests/