Fuzz introspector
For issues and ideas: https://github.com/ossf/fuzz-introspector/issues
Report generation date: 2025-07-18

Project overview: dulwich

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
5.0%
99 / 2063
Cyclomatic complexity statically reachable by fuzzers
5.0%
359 / 7392
Runtime code coverage of functions
14.0%
296 / 2063

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: fuzz_object_store

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 75.2%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 23 24.7%
All colors 93 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
40 27 ...dulwich.fuzzing.fuzz-targets.fuzz_object_store.TestOneInput call site: 00027 dulwich.patch.write_tree_diff
24 68 dulwich.objects.S_ISGITLINK call site: 00068 dulwich.patch.write_object_diff.content
2 0 EP call site: 00000 dulwich.repo.MemoryRepo.__init__
2 19 ...dulwich.fuzzing.fuzz-targets.fuzz_object_store.TestOneInput call site: 00019 dulwich.objects.Commit.__init__
2 23 ...dulwich.fuzzing.fuzz-targets.fuzz_object_store.TestOneInput call site: 00023 test_utils.EnhancedFuzzedDataProvider.ConsumeRandomBytes

Runtime coverage analysis

Covered functions
327
Functions that are reachable but not covered
36
Reachable functions
48
Percentage of reachable functions covered
25.0%
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
...dulwich.fuzzing.fuzz-targets.fuzz_object_store 12
dulwich.repo 4
dulwich.refs 2
dulwich.object_store 1
dulwich.config 2
dulwich.objects 4
dulwich.patch 23
dulwich.diff 5

Fuzzer: fuzz_repo

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 0 124 41.4%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 175 58.5%
All colors 299 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
25 161 dulwich.config.ConfigDict.items call site: 00161 dulwich.object_store.DiskObjectStore.from_config
23 190 dulwich.config.StackedConfig.get call site: 00190 dulwich.reftable.ReftableRefsContainer.__init__
16 255 dulwich.config.StackedConfig.default_backends call site: 00255 dulwich.config.get_win_system_paths
9 215 dulwich.repo.Repo.__init__ call site: 00215 dulwich.repo.parse_graftpoints
7 37 dulwich.repo.Repo.__init__ call site: 00037 os.path.isfile
7 277 dulwich.repo.Repo._init_maybe_bare call site: 00277 test_utils.EnhancedFuzzedDataProvider.ConsumeRandomBytes
6 45 dulwich.repo.Repo.__init__ call site: 00045 dulwich.repo.read_gitfile
4 56 dulwich.repo.Repo.get_named_file call site: 00056 os.path.join
4 288 ...dulwich.fuzzing.fuzz-targets.fuzz_repo.TestOneInput call site: 00288 repo.stage
4 294 ...dulwich.fuzzing.fuzz-targets.fuzz_repo.TestOneInput call site: 00294 test_utils.EnhancedFuzzedDataProvider.ConsumeRandomInt
3 0 EP call site: 00000 dulwich.repo.Repo.init
3 10 dulwich.repo.Repo.init call site: 00010 ctypes.WINFUNCTYPE

Runtime coverage analysis

Covered functions
327
Functions that are reachable but not covered
88
Reachable functions
126
Percentage of reachable functions covered
30.16%
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
...dulwich.fuzzing.fuzz-targets.fuzz_repo 17
dulwich.repo 45
dulwich.object_store 7
dulwich.refs 3
dulwich.config 64
dulwich.reftable 11
dulwich.objects 3
dulwich.hooks 2

Fuzzer: fuzz_bundle

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 0 195 92.8%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 15 7.14%
All colors 210 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
100 10 ...dulwich.fuzzing.fuzz-targets.fuzz_bundle.TestOneInput call site: 00010 dulwich.pack.pack_objects_to_data
59 124 dulwich.file.GitFile call site: 00124 dulwich.bundle.write_bundle
24 184 ...dulwich.fuzzing.fuzz-targets.fuzz_bundle.TestOneInput call site: 00184 dulwich.bundle._read_bundle
7 1 ...dulwich.fuzzing.fuzz-targets.fuzz_bundle.TestOneInput call site: 00001 test_utils.EnhancedFuzzedDataProvider.PickValueInList
4 111 ...dulwich.fuzzing.fuzz-targets.fuzz_bundle.TestOneInput call site: 00111 dulwich.pack.PackData.from_file
1 119 dulwich.file._GitFile.__init__ call site: 00119 .getattr

Runtime coverage analysis

Covered functions
327
Functions that are reachable but not covered
110
Reachable functions
113
Percentage of reachable functions covered
2.65%
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
...dulwich.fuzzing.fuzz-targets.fuzz_bundle 13
dulwich.pack 76
dulwich.file 8
dulwich.contrib.swift 6
dulwich.bundle 24

Fuzzer: fuzz_configfile

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 1 1.31%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 75 98.6%
All colors 76 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
1 5 dulwich.config.ConfigFile.__init__ call site: 00005 included_paths.copy

Runtime coverage analysis

Covered functions
328
Functions that are reachable but not covered
27
Reachable functions
35
Percentage of reachable functions covered
22.86%
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
...dulwich.fuzzing.fuzz-targets.fuzz_configfile 3
dulwich.config 31

Analyses and suggestions

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
dulwich.porcelain.clone dulwich.porcelain 14 ['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'] 9 0 7 9 7 383 4 1280 877
dulwich.repo.Repo.clone dulwich.repo 10 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 8 0 12 8 6 405 0 1347 771
dulwich.cli.cmd_lfs.run dulwich.cli 2 ['N/A', 'N/A'] 10 0 42 20 11 324 0 1099 655
dulwich.client.GitClient.fetch dulwich.client 9 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 7 0 4 2 4 325 0 1080 307
dulwich.repo.BaseRepo.do_commit dulwich.repo 14 ['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 14 24 13 289 0 965 269
dulwich.porcelain.pull dulwich.porcelain 11 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 8 0 5 8 6 317 1 1070 217
dulwich.object_store.DiskObjectStore._complete_pack dulwich.object_store 6 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 8 0 13 3 4 129 2 408 167

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

Functions statically reachable by fuzzers
26.0%
535 / 2063
Cyclomatic complexity statically reachable by fuzzers
28.0%
2053 / 7392

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 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

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.

/src/dulwich/fuzzing/fuzz-targets/fuzz_object_store.py

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=['...dulwich.fuzzing.fuzz-targets.fuzz_object_store.TestOneInput', 'dulwich.objects.S_ISGITLINK']

/src/dulwich/fuzzing/fuzz-targets/fuzz_repo.py

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=['dulwich.config.ConfigDict.items', 'dulwich.config.StackedConfig.get', 'dulwich.config.StackedConfig.default_backends', 'dulwich.repo.Repo.__init__', 'dulwich.repo.Repo._init_maybe_bare', 'dulwich.repo.Repo.get_named_file', '...dulwich.fuzzing.fuzz-targets.fuzz_repo.TestOneInput']

/src/dulwich/fuzzing/fuzz-targets/fuzz_bundle.py

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=['...dulwich.fuzzing.fuzz-targets.fuzz_bundle.TestOneInput', 'dulwich.file.GitFile', 'dulwich.file._GitFile.__init__']

/src/dulwich/fuzzing/fuzz-targets/fuzz_configfile.py

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=['dulwich.config.ConfigFile.__init__']

Runtime coverage analysis

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
dulwich.repo.Repo.stage 39 21 53.84% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
dulwich.repo.Repo.clone 40 0 0.0% []
dulwich.repo.Repo.get_gitattributes 37 13 35.13% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
dulwich.objects.Tag._deserialize 31 0 0.0% []
dulwich.objects.parse_commit 45 5 11.11% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
dulwich.objects.Commit.check 32 0 0.0% []
dulwich.patch.parse_patch_message 39 0 0.0% []
dulwich.config.ConfigFile._evaluate_hasconfig_condition 34 0 0.0% []
dulwich.object_store.DiskObjectStore.from_config 44 0 0.0% ['fuzz_repo']
dulwich.object_store.DiskObjectStore._complete_pack 31 0 0.0% []
dulwich.object_store.DiskObjectStore.write_commit_graph 33 0 0.0% []
dulwich.pack.read_zlib_chunks 33 0 0.0% []
dulwich.pack.unpack_object 32 0 0.0% []
dulwich.pack.PackChunkGenerator._pack_data_chunks 38 0 0.0% ['fuzz_bundle']
dulwich.pack.apply_delta.get_delta_header_size 44 0 0.0% []
dulwich.pack.write_pack_index_v3 37 0 0.0% []
dulwich.refs.DiskRefsContainer.set_if_equals 39 0 0.0% []
dulwich.refs.DiskRefsContainer.remove_if_equals 34 0 0.0% []
dulwich.index._decompress_path_from_stream 47 19 40.42% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
dulwich.index.read_index_dict_with_version 42 18 42.85% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
dulwich.index._transition_to_file 32 0 0.0% []
dulwich.index.detect_case_only_renames.normalize_path 43 0 0.0% []
dulwich.index.update_working_tree 88 0 0.0% []
dulwich.gc.find_reachable_objects 38 0 0.0% []
dulwich.gc.garbage_collect 52 0 0.0% []
dulwich.gc.maybe_auto_gc 34 2 5.882% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
dulwich.diff_tree.walk_trees 50 9 18.0% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
dulwich.attrs._translate_pattern 44 2 4.545% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
repo.object_store.tree_changes 44 23 52.27% ['fuzz_configfile', 'fuzz_bundle', 'fuzz_object_store', 'fuzz_repo']
dulwich.protocol.ReceivableProtocol.read 31 0 0.0% []

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
[] []
datetime [] []
gc [] []
replace_me [] []
gpg [] []
dulwich.gc [] []
wsgiref [] []
dulwich.porcelain [] []
dulwich.sparse_patterns [] []
nturl2path [] []
dulwich.cli [] []
dulwich.lfs [] []
...dulwich.fuzzing.fuzz-targets.fuzz_repo ['fuzz_repo'] []
dulwich.notes [] []
gzip [] []
sys [] []
collections [] []
typing [] []
os [] []
paramiko [] []
dulwich.cloud [] []
dulwich.bisect [] []
select [] []
glob [] []
configparser [] []
socket [] []
dulwich.bundle ['fuzz_bundle'] []
json [] []
itertools [] []
cdifflib [] []
dulwich.attrs [] []
shlex [] []
dulwich.ignore [] []
pwd [] []
re [] []
dataclasses [] []
http [] []
typing_extensions [] []
dulwich.file ['fuzz_bundle'] []
zlib [] []
functools [] []
socketserver [] []
dulwich.log_utils [] []
dulwich.lru_cache [] []
dulwich.reftable ['fuzz_repo'] []
merge3 [] []
dulwich.client [] []
ctypes [] []
warnings [] []
pathlib [] []
dulwich.filter_branch [] []
dulwich.protocol [] []
...dulwich.fuzzing.fuzz-targets.fuzz_configfile ['fuzz_configfile'] []
dulwich.diff_tree [] []
dulwich.submodule [] []
...dulwich.fuzzing.fuzz-targets.fuzz_bundle ['fuzz_bundle'] []
dulwich.walk [] []
dulwich.diff ['fuzz_object_store'] []
fastimport [] []
optparse [] []
dulwich.credentials [] []
contextlib [] []
stat [] []
dulwich.stash [] []
dulwich [] []
dulwich.cloud.gcs [] []
dulwich.filters [] []
difflib [] []
requests [] []
signal [] []
atheris [] []
dulwich.contrib.release_robot [] []
dulwich.patch ['fuzz_object_store'] []
dulwich.dumb [] []
test_utils [] []
winreg [] []
win32api [] []
dulwich.greenthreads [] []
dulwich.reflog [] []
struct [] []
dulwich.__main__ [] []
binascii [] []
[] []
dulwich.commit_graph [] []
dulwich.fastexport [] []
msvcrt [] []
pdb [] []
dulwich.objects ['fuzz_object_store', 'fuzz_repo'] []
heapq [] []
dulwich.contrib.paramiko_vendor [] []
time [] []
dulwich.repo ['fuzz_object_store', 'fuzz_repo'] []
urllib [] []
dulwich.merge_drivers [] []
logging [] []
random [] []
mmap [] []
tarfile [] []
dulwich.config ['fuzz_object_store', 'fuzz_repo', 'fuzz_configfile'] []
dulwich.errors [] []
posixpath [] []
dulwich.pack ['fuzz_bundle'] []
dulwich.contrib.diffstat [] []
io [] []
geventhttpclient [] []
dulwich.index [] []
dulwich.line_ending [] []
hashlib [] []
unicodedata [] []
...dulwich.fuzzing.fuzz-targets.fuzz_object_store ['fuzz_object_store'] []
dulwich.web [] []
argparse [] []
rich [] []
fnmatch [] []
copy [] []
subprocess [] []
dulwich.contrib.requests_vendor [] []
shutil [] []
urllib3 [] []
dulwich.hooks ['fuzz_repo'] []
dulwich.objectspec [] []
dulwich.server [] []
dulwich.annotate [] []
dulwich.mailmap [] []
platform [] []
dulwich.refs ['fuzz_object_store', 'fuzz_repo'] []
dulwich.contrib.swift ['fuzz_bundle'] []
dulwich.contrib [] []
dulwich.graph [] []
dulwich.object_store ['fuzz_object_store', 'fuzz_repo'] []
dulwich.archive [] []
dulwich.merge [] []
tempfile [] []
dulwich.lfs_server [] []
gevent [] []
dulwich.rebase [] []
ipaddress [] []

Directories in report

Directory