High level conclusions

Fuzzers reach 55.30% code coverage.

Fuzzers reach 39.29% of cyclomatic complexity.

Fuzzers reach 25.39% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

304 / 1197

Cyclomatic complexity statically reachable by fuzzers

4043 / 10288

Runtime code coverage of functions

662 / 1197

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	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: cbor_fuzzer

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	23	16.5%
gold	[1:9]	2	1.43%
yellow	[10:29]	1	0.71%
greenyellow	[30:49]	1	0.71%
lawngreen	50+	112	80.5%
All colors	139	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
5	13	fuzz_complex	call site: 00013	wuffs_base__make_status
4	25	fuzz_complex	call site: 00025	wuffs_base__make_status
2	133	llvmFuzzerTestOneInput	call site: 00133	fprintf
2	136	llvmFuzzerTestOneInput	call site: 00136	fprintf
1	19	fuzz_complex	call site: 00019	wuffs_base__status__message
1	30	wuffs_cbor__decoder__decode_tokens	call site: 00030	wuffs_base__make_status
1	43	wuffs_cbor__decoder__decode_tokens	call site: 00043	wuffs_base__make_status
1	58	wuffs_cbor__decoder__decode_tokens	call site: 00058	wuffs_base__make_status
1	68	wuffs_base__utf_8__longest_valid_prefix	call site: 00068	wuffs_base__make_utf_8__next__output
1	79	wuffs_cbor__decoder__decode_tokens	call site: 00079	wuffs_base__make_status
1	92	wuffs_cbor__decoder__decode_tokens	call site: 00092	wuffs_base__make_status
1	97	wuffs_cbor__decoder__decode_tokens	call site: 00097	wuffs_base__make_status

Runtime coverage analysis

Covered functions

42

Functions that are reachable but not covered

5

Reachable functions

47

Percentage of reachable functions covered

89.36%

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.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	6
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	32
/src/wuffs/fuzz/c/std/cbor_fuzzer.c	6

Fuzzer: bzip2_fuzzer

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	23	17.5%
gold	[1:9]	14	10.6%
yellow	[10:29]	14	10.6%
greenyellow	[30:49]	8	6.10%
lawngreen	50+	72	54.9%
All colors	131	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
5	7	fuzz	call site: 00007	wuffs_base__make_status
4	22	fuzz	call site: 00022	wuffs_base__make_status
2	15	fuzz	call site: 00015	wuffs_base__make_status
2	120	wuffs_bzip2__decoder__transform_io	call site: 00120	fprintf
2	125	llvmFuzzerTestOneInput	call site: 00125	fprintf
2	128	llvmFuzzerTestOneInput	call site: 00128	fprintf
1	13	fuzz	call site: 00013	wuffs_base__status__message
1	18	wuffs_bzip2__decoder__set_quirk	call site: 00018	wuffs_base__make_status
1	31	wuffs_bzip2__decoder__do_transform_io	call site: 00031	wuffs_base__make_status
1	80	wuffs_bzip2__decoder__decode_huffman_fast	call site: 00080	wuffs_base__make_status
1	85	wuffs_bzip2__decoder__decode_huffman_fast	call site: 00085	wuffs_base__make_status
1	97	wuffs_bzip2__decoder__decode_huffman_slow	call site: 00097	wuffs_base__make_status

Runtime coverage analysis

Covered functions

31

Functions that are reachable but not covered

4

Reachable functions

35

Percentage of reachable functions covered

88.57%

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.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	26
/src/wuffs/fuzz/c/std/bzip2_fuzzer.c	1

Fuzzer: targa_fuzzer

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	38	43.6%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	49	56.3%
All colors	87	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
5	7	fuzz	call site: 00007	wuffs_base__make_status
4	29	fuzz_image_decoder	call site: 00029	wuffs_base__malloc_slice_u8
4	48	wuffs_base__pixel_buffer__set_from_slice	call site: 00048	wuffs_base__make_status
3	18	fuzz_image_decoder	call site: 00018	wuffs_base__make_status
3	53	fuzz_image_decoder	call site: 00053	wuffs_base__make_status
3	59	fuzz_image_decoder	call site: 00059	wuffs_base__make_status
3	64	fuzz_image_decoder	call site: 00064	wuffs_base__empty_rect_ie_u32
2	41	fuzz_image_decoder	call site: 00041	wuffs_base__make_status
2	74	wuffs_base__rect_ie_u32__contains_rect	call site: 00074	wuffs_base__rect_ie_u32__is_empty
2	81	llvmFuzzerTestOneInput	call site: 00081	fprintf
2	84	llvmFuzzerTestOneInput	call site: 00084	fprintf
1	14	fuzz	call site: 00014	wuffs_base__status__message

Runtime coverage analysis

Covered functions

82

Functions that are reachable but not covered

7

Reachable functions

44

Percentage of reachable functions covered

84.09%

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
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	34
/src/wuffs/fuzz/c/std/targa_fuzzer.c	1
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib_image_decoder.c	1

Fuzzer: zlib_fuzzer

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	88	37.4%
gold	[1:9]	11	4.68%
yellow	[10:29]	12	5.10%
greenyellow	[30:49]	6	2.55%
lawngreen	50+	118	50.2%
All colors	235	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
17	95	wuffs_deflate__decoder__init_huff	call site: 00095	wuffs_base__make_status
6	19	wuffs_zlib__decoder__initialize	call site: 00019	wuffs_base__make_status
5	12	wuffs_zlib__decoder__initialize	call site: 00012	wuffs_base__make_status
4	7	fuzz	call site: 00007	wuffs_base__make_status
4	37	fuzz	call site: 00037	wuffs_base__make_status
4	54	wuffs_zlib__decoder__do_transform_io	call site: 00054	wuffs_base__make_status
4	59	wuffs_zlib__decoder__do_transform_io	call site: 00059	wuffs_base__make_status
3	28	fuzz	call site: 00028	wuffs_base__make_status
3	118	wuffs_deflate__decoder__decode_blocks	call site: 00118	wuffs_base__status__is_error
3	153	wuffs_deflate__decoder__decode_huffman_slow	call site: 00153	wuffs_base__make_status
3	165	wuffs_deflate__decoder__decode_huffman_slow	call site: 00165	wuffs_private_impl__io_writer__limited_copy_u32_from_slice
3	193	wuffs_base__slice_u8__subslice_i	call site: 00193	wuffs_private_impl__slice_u8__copy_from_slice

Runtime coverage analysis

Covered functions

58

Functions that are reachable but not covered

9

Reachable functions

57

Percentage of reachable functions covered

84.21%

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
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	45
/src/wuffs/fuzz/c/std/zlib_fuzzer.c	1
/usr/local/lib/clang/22/include/cpuid.h	3

Fuzzer: gif_fuzzer

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	39	40.6%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	57	59.3%
All colors	96	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
5	7	fuzz	call site: 00007	wuffs_base__make_status
4	36	fuzz_image_decoder	call site: 00036	wuffs_base__malloc_slice_u8
4	55	wuffs_base__pixel_buffer__set_from_slice	call site: 00055	wuffs_base__make_status
3	25	fuzz_image_decoder	call site: 00025	wuffs_base__make_status
3	62	fuzz_image_decoder	call site: 00062	wuffs_base__make_status
3	68	fuzz_image_decoder	call site: 00068	wuffs_base__make_status
3	73	fuzz_image_decoder	call site: 00073	wuffs_base__empty_rect_ie_u32
2	18	set_quirks	call site: 00018	wuffs_base__make_status
2	48	fuzz_image_decoder	call site: 00048	wuffs_base__make_status
2	90	llvmFuzzerTestOneInput	call site: 00090	fprintf
2	93	llvmFuzzerTestOneInput	call site: 00093	fprintf
1	15	fuzz	call site: 00015	wuffs_base__status__message

Runtime coverage analysis

Covered functions

101

Functions that are reachable but not covered

6

Reachable functions

46

Percentage of reachable functions covered

86.96%

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
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	35
/src/wuffs/fuzz/c/std/gif_fuzzer.c	2
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib_image_decoder.c	1

Fuzzer: bmp_fuzzer

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	38	43.6%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	49	56.3%
All colors	87	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
5	7	fuzz	call site: 00007	wuffs_base__make_status
4	29	fuzz_image_decoder	call site: 00029	wuffs_base__malloc_slice_u8
4	48	wuffs_base__pixel_buffer__set_from_slice	call site: 00048	wuffs_base__make_status
3	18	fuzz_image_decoder	call site: 00018	wuffs_base__make_status
3	53	fuzz_image_decoder	call site: 00053	wuffs_base__make_status
3	59	fuzz_image_decoder	call site: 00059	wuffs_base__make_status
3	64	fuzz_image_decoder	call site: 00064	wuffs_base__empty_rect_ie_u32
2	41	fuzz_image_decoder	call site: 00041	wuffs_base__make_status
2	74	wuffs_base__rect_ie_u32__contains_rect	call site: 00074	wuffs_base__rect_ie_u32__is_empty
2	81	llvmFuzzerTestOneInput	call site: 00081	fprintf
2	84	llvmFuzzerTestOneInput	call site: 00084	fprintf
1	14	fuzz	call site: 00014	wuffs_base__status__message

Runtime coverage analysis

Covered functions

104

Functions that are reachable but not covered

7

Reachable functions

44

Percentage of reachable functions covered

84.09%

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
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	34
/src/wuffs/fuzz/c/std/bmp_fuzzer.c	1
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib_image_decoder.c	1

Fuzzer: pixel_swizzler_fuzzer

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	24	14.7%
gold	[1:9]	13	7.97%
yellow	[10:29]	1	0.61%
greenyellow	[30:49]	2	1.22%
lawngreen	50+	123	75.4%
All colors	163	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
4	87	wuffs_base__pixel_buffer__set_from_slice	call site: 00087	wuffs_base__make_status
3	103	fuzz_swizzle_ycck	call site: 00103	wuffs_base__make_status
2	80	fuzz_swizzle_ycck	call site: 00080	wuffs_base__make_status
2	157	llvmFuzzerTestOneInput	call site: 00157	fprintf
2	160	llvmFuzzerTestOneInput	call site: 00160	fprintf
1	12	fuzz_swizzle_interleaved_from_slice	call site: 00012	wuffs_base__make_status
1	14	wuffs_base__pixel_swizzler__prepare	call site: 00014	wuffs_base__make_status
1	16	wuffs_base__pixel_swizzler__prepare	call site: 00016	wuffs_base__make_status
1	19	wuffs_base__cpu_arch__have_x86_sse42	call site: 00019	__get_cpuid_max
1	47	wuffs_base__pixel_swizzler__prepare	call site: 00047	wuffs_base__cpu_arch__have_x86_sse42
1	83	wuffs_base__pixel_buffer__set_from_slice	call site: 00083	wuffs_base__make_status
1	85	wuffs_base__pixel_buffer__set_from_slice	call site: 00085	wuffs_base__make_status

Runtime coverage analysis

Covered functions

262

Functions that are reachable but not covered

10

Reachable functions

55

Percentage of reachable functions covered

81.82%

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
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	36
/src/wuffs/fuzz/c/std/pixel_swizzler_fuzzer.c	5
/usr/local/lib/clang/22/include/cpuid.h	3

Fuzzer: png_fuzzer

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	57	50.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	57	50.0%
All colors	114	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
7	30	wuffs_zlib__decoder__initialize	call site: 00030	wuffs_base__make_status
5	12	wuffs_png__decoder__initialize	call site: 00012	wuffs_base__make_status
5	23	wuffs_zlib__decoder__initialize	call site: 00023	wuffs_base__make_status
4	7	fuzz	call site: 00007	wuffs_base__make_status
4	18	wuffs_png__decoder__initialize	call site: 00018	wuffs_base__make_status
4	73	wuffs_base__pixel_buffer__set_from_slice	call site: 00073	wuffs_base__make_status
3	43	fuzz_image_decoder	call site: 00043	wuffs_base__make_status
3	54	fuzz_image_decoder	call site: 00054	wuffs_base__empty_range_ii_u64
3	80	fuzz_image_decoder	call site: 00080	wuffs_base__make_status
3	86	fuzz_image_decoder	call site: 00086	wuffs_base__make_status
3	91	fuzz_image_decoder	call site: 00091	wuffs_base__empty_rect_ie_u32
2	66	fuzz_image_decoder	call site: 00066	wuffs_base__make_status

Runtime coverage analysis

Covered functions

180

Functions that are reachable but not covered

7

Reachable functions

48

Percentage of reachable functions covered

85.42%

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
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	38
/src/wuffs/fuzz/c/std/png_fuzzer.c	1
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib_image_decoder.c	1

Fuzzer: json_fuzzer

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	57	12.8%
gold	[1:9]	9	2.03%
yellow	[10:29]	6	1.35%
greenyellow	[30:49]	8	1.80%
lawngreen	50+	363	81.9%
All colors	443	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
11	342	wuffs_base__parse_number_f64	call site: 00342
5	28	wuffs_json__decoder__alloc	call site: 00028
4	44	wuffs_json__decoder__struct::decode_tokens(wuffs_base__token_buffer__struct*, wuffs_base__io_buffer__struct*, wuffs_base__slice_u8)	call site: 00044
3	354	wuffs_private_impl__high_prec_dec__parse(wuffs_private_impl__high_prec_dec__struct*, wuffs_base__slice_u8, unsigned int)	call site: 00354
2	35	wuffs_json__decoder__struct::set_quirk(unsigned int, unsigned long)	call site: 00035
2	49	wuffs_json__decoder__decode_tokens	call site: 00049
2	131	wuffs_json__decoder__decode_tokens	call site: 00131
2	254	wuffs_aux::(anonymous namespace)::DecodeJson_WalkJsonPointerFragment(wuffs_base__token_buffer__struct&, wuffs_base__status__struct&, std::__1::unique_ptr &, wuffs_base__io_buffer__struct*, std::__1::basic_string , std::__1::allocator >&, unsigned long&, wuffs_aux::sync_io::Input&, std::__1::basic_string , std::__1::allocator >&)	call site: 00254
2	421	wuffs_base__utf_8__next	call site: 00421	wuffs_base__ascii__longest_valid_prefix
2	437	llvmFuzzerTestOneInput(unsigned char const*, unsigned long)	call site: 00437	fprintf
2	440	llvmFuzzerTestOneInput(unsigned char const*, unsigned long)	call site: 00440	fprintf
1	16	fuzz_cpp(unsigned char const*, unsigned long, unsigned long)	call site: 00016

Runtime coverage analysis

Covered functions

102

Functions that are reachable but not covered

24

Reachable functions

199

Percentage of reachable functions covered

87.94%

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.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	6
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	89
/src/wuffs/fuzz/c/std/json_fuzzer.cc	9

Fuzzer: xz_fuzzer

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	130	24.3%
gold	[1:9]	45	8.42%
yellow	[10:29]	32	5.99%
greenyellow	[30:49]	21	3.93%
lawngreen	50+	306	57.3%
All colors	534	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
11	162	wuffs_lzma__decoder__do_transform_io	call site: 00162	wuffs_lzma__decoder__initialize_probs
8	102	wuffs_xz__decoder__decode_block_header_sans_padding	call site: 00102	wuffs_lzma__decoder__set_quirk
6	30	wuffs_xz__decoder__initialize	call site: 00030	wuffs_base__make_status
5	12	wuffs_xz__decoder__initialize	call site: 00012	wuffs_base__make_status
5	18	wuffs_xz__decoder__initialize	call site: 00018	wuffs_base__make_status
5	24	wuffs_xz__decoder__initialize	call site: 00024	wuffs_base__make_status
4	7	fuzz	call site: 00007	wuffs_base__make_status
4	47	fuzz	call site: 00047	wuffs_base__make_status
4	152	wuffs_xz__decoder__do_transform_io	call site: 00152	wuffs_base__make_status
4	514	wuffs_xz__decoder__do_transform_io	call site: 00514	wuffs_base__make_status
2	39	fuzz	call site: 00039	wuffs_base__make_status
2	42	wuffs_xz__decoder__set_quirk	call site: 00042	wuffs_base__make_status

Runtime coverage analysis

Covered functions

96

Functions that are reachable but not covered

9

Reachable functions

93

Percentage of reachable functions covered

90.32%

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
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	82
/src/wuffs/fuzz/c/std/xz_fuzzer.c	1
/usr/local/lib/clang/22/include/cpuid.h	2

Fuzzer: jpeg_fuzzer

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	37	42.5%
gold	[1:9]	1	1.14%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	49	56.3%
All colors	87	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
5	7	fuzz	call site: 00007	wuffs_base__make_status
4	48	wuffs_base__pixel_buffer__set_from_slice	call site: 00048	wuffs_base__make_status
3	18	fuzz_image_decoder	call site: 00018	wuffs_base__make_status
3	29	fuzz_image_decoder	call site: 00029	wuffs_base__empty_range_ii_u64
3	53	fuzz_image_decoder	call site: 00053	wuffs_base__make_status
3	59	fuzz_image_decoder	call site: 00059	wuffs_base__make_status
3	64	fuzz_image_decoder	call site: 00064	wuffs_base__empty_rect_ie_u32
2	41	fuzz_image_decoder	call site: 00041	wuffs_base__make_status
2	74	wuffs_base__rect_ie_u32__contains_rect	call site: 00074	wuffs_base__rect_ie_u32__is_empty
2	81	llvmFuzzerTestOneInput	call site: 00081	fprintf
2	84	llvmFuzzerTestOneInput	call site: 00084	fprintf
1	14	fuzz	call site: 00014	wuffs_base__status__message

Runtime coverage analysis

Covered functions

146

Functions that are reachable but not covered

7

Reachable functions

44

Percentage of reachable functions covered

84.09%

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
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	5
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	34
/src/wuffs/fuzz/c/std/jpeg_fuzzer.c	1
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib_image_decoder.c	1

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
wuffs_png__decoder__decode_frame	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	7	['N/A', 'N/A', 'N/A', 'char', 'N/A', 'size_t', 'N/A']	10	0	267	43	14	101	0	1702	586
wuffs_jpeg__decoder__decode_frame	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	7	['N/A', 'N/A', 'N/A', 'char', 'N/A', 'size_t', 'N/A']	6	0	397	62	21	91	0	1381	548
wuffs_gif__decoder__decode_frame	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	7	['N/A', 'N/A', 'N/A', 'char', 'N/A', 'size_t', 'N/A']	8	0	267	43	14	72	0	1141	394
wuffs_bmp__decoder__decode_frame	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	7	['N/A', 'N/A', 'N/A', 'char', 'N/A', 'size_t', 'N/A']	5	0	267	43	14	60	0	1123	385
wuffs_targa__decoder__decode_frame	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	7	['N/A', 'N/A', 'N/A', 'char', 'N/A', 'size_t', 'N/A']	5	0	267	43	14	43	0	892	172
wuffs_base__render_number_f64	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	5	['N/A', 'size_t', 'double', 'int', 'int']	4	0	369	52	17	19	0	150	146
wuffs_png__decoder__tell_me_more	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	4	['N/A', 'N/A', 'N/A', 'N/A']	9	0	255	43	14	56	0	579	139
wuffs_base__pixel_buffer__set_color_u32_fill_rect	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	4	['N/A', 'size_t', 'size_t', 'int']	3	0	255	33	7	36	0	117	76
wuffs_aux::private_impl::HandleMetadata(wuffs_aux::private_impl::ErrorMessagesconst&,wuffs_aux::sync_io::Input&,wuffs_base__io_buffer__struct&,wuffs_aux::sync_io::DynIOBuffer&,wuffs_base__status__struct(*)(void*,wuffs_base__io_buffer__struct*,wuffs_base__more_information__struct*,wuffs_base__io_buffer__struct*),void*,std::__1::basic_string ,std::__1::allocator >(*)(void*,wuffs_base__more_information__structconst*,wuffs_base__slice_u8),void*)	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	9	['N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A', 'N/A']	4	0	457	70	10	63	0	97	68
wuffs_private_impl__high_prec_dec__parse	/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	4	['N/A', 'N/A', 'size_t', 'int']	1	0	978	202	63	2	1	68	63

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

Functions statically reachable by fuzzers

471 / 1197

Cyclomatic complexity statically reachable by fuzzers

6618 / 10288

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

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/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['fuzz_complex', 'llvmFuzzerTestOneInput', 'wuffs_cbor__decoder__decode_tokens', 'wuffs_base__utf_8__longest_valid_prefix']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['fuzz', 'wuffs_bzip2__decoder__transform_io', 'llvmFuzzerTestOneInput', 'wuffs_bzip2__decoder__set_quirk', 'wuffs_bzip2__decoder__do_transform_io', 'wuffs_bzip2__decoder__decode_huffman_fast']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['fuzz', 'fuzz_image_decoder', 'wuffs_base__pixel_buffer__set_from_slice', 'wuffs_base__rect_ie_u32__contains_rect', 'llvmFuzzerTestOneInput']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['wuffs_deflate__decoder__init_huff', 'wuffs_zlib__decoder__initialize', 'fuzz', 'wuffs_zlib__decoder__do_transform_io', 'wuffs_deflate__decoder__decode_blocks', 'wuffs_deflate__decoder__decode_huffman_slow']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['fuzz', 'fuzz_image_decoder', 'wuffs_base__pixel_buffer__set_from_slice', 'set_quirks', 'llvmFuzzerTestOneInput']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['fuzz', 'fuzz_image_decoder', 'wuffs_base__pixel_buffer__set_from_slice', 'wuffs_base__rect_ie_u32__contains_rect', 'llvmFuzzerTestOneInput']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['wuffs_base__pixel_buffer__set_from_slice', 'fuzz_swizzle_ycck', 'llvmFuzzerTestOneInput', 'fuzz_swizzle_interleaved_from_slice', 'wuffs_base__pixel_swizzler__prepare', 'wuffs_base__cpu_arch__have_x86_sse42']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['wuffs_zlib__decoder__initialize', 'wuffs_png__decoder__initialize', 'fuzz', 'wuffs_base__pixel_buffer__set_from_slice', 'fuzz_image_decoder']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['wuffs_base__parse_number_f64', 'wuffs_json__decoder__alloc', 'wuffs_json__decoder__struct::decode_tokens(wuffs_base__token_buffer__struct*, wuffs_base__io_buffer__struct*, wuffs_base__slice_u8)', 'wuffs_private_impl__high_prec_dec__parse(wuffs_private_impl__high_prec_dec__struct*, wuffs_base__slice_u8, unsigned int)', 'wuffs_json__decoder__struct::set_quirk(unsigned int, unsigned long)', 'wuffs_json__decoder__decode_tokens', 'wuffs_aux::(anonymous namespace)::DecodeJson_WalkJsonPointerFragment(wuffs_base__token_buffer__struct&, wuffs_base__status__struct&, std::__1::unique_ptr&, wuffs_base__io_buffer__struct*, std::__1::basic_string, std::__1::allocator >&, unsigned long&, wuffs_aux::sync_io::Input&, std::__1::basic_string, std::__1::allocator >&)', 'wuffs_base__utf_8__next', 'llvmFuzzerTestOneInput(unsigned char const*, unsigned long)']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['wuffs_lzma__decoder__do_transform_io', 'wuffs_xz__decoder__decode_block_header_sans_padding', 'wuffs_xz__decoder__initialize', 'fuzz', 'wuffs_xz__decoder__do_transform_io']

/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c

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=['fuzz', 'wuffs_base__pixel_buffer__set_from_slice', 'fuzz_image_decoder', 'wuffs_base__rect_ie_u32__contains_rect', 'llvmFuzzerTestOneInput']

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
wuffs_targa__decoder__decode_frame_config	52	27	51.92%	['targa_fuzzer']
wuffs_bmp__decoder__decode_frame_config	52	27	51.92%	['bmp_fuzzer']
wuffs_base__parse_number_u64	131	57	43.51%	['json_fuzzer']
wuffs_lzma__decoder__set_quirk	46	24	52.17%	['xz_fuzzer']
wuffs_jpeg__decoder__decode_frame_config	52	27	51.92%	['jpeg_fuzzer']

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
	[]	[]
/usr/local/bin/../include/c++/v1/stdexcept	[]	[]
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib_image_decoder.c	['targa_fuzzer', 'gif_fuzzer', 'bmp_fuzzer', 'png_fuzzer', 'jpeg_fuzzer']	[]
/usr/local/bin/../include/c++/v1/string	[]	[]
/src/wuffs/fuzz/c/std/bzip2_fuzzer.c	['bzip2_fuzzer']	['bzip2_fuzzer']
/src/wuffs/fuzz/c/std/zlib_fuzzer.c	['zlib_fuzzer']	['zlib_fuzzer']
/src/wuffs/fuzz/c/std/jpeg_fuzzer.c	['jpeg_fuzzer']	['jpeg_fuzzer']
/src/wuffs/fuzz/c/std/xz_fuzzer.c	['xz_fuzzer']	['xz_fuzzer']
/usr/local/lib/clang/22/include/cpuid.h	['zlib_fuzzer', 'pixel_swizzler_fuzzer', 'xz_fuzzer']	[]
/src/wuffs/fuzz/c/std/json_fuzzer.cc	['json_fuzzer']	['json_fuzzer']
/src/wuffs/fuzz/c/std/targa_fuzzer.c	['targa_fuzzer']	['targa_fuzzer']
/src/wuffs/fuzz/c/std/gif_fuzzer.c	['gif_fuzzer']	['gif_fuzzer']
/src/wuffs/fuzz/c/std/pixel_swizzler_fuzzer.c	['pixel_swizzler_fuzzer']	['pixel_swizzler_fuzzer']
/src/wuffs/fuzz/c/std/cbor_fuzzer.c	['cbor_fuzzer']	['cbor_fuzzer']
/src/wuffs/fuzz/c/std/../fuzzlib/fuzzlib.c	['cbor_fuzzer', 'bzip2_fuzzer', 'targa_fuzzer', 'zlib_fuzzer', 'gif_fuzzer', 'bmp_fuzzer', 'pixel_swizzler_fuzzer', 'png_fuzzer', 'json_fuzzer', 'xz_fuzzer', 'jpeg_fuzzer']	[]
/src/wuffs/fuzz/c/std/png_fuzzer.c	['png_fuzzer']	['png_fuzzer']
/src/wuffs/fuzz/c/std/bmp_fuzzer.c	['bmp_fuzzer']	['bmp_fuzzer']
/src/wuffs/fuzz/c/std/../../../release/c/wuffs-unsupported-snapshot.c	['cbor_fuzzer', 'bzip2_fuzzer', 'targa_fuzzer', 'zlib_fuzzer', 'gif_fuzzer', 'bmp_fuzzer', 'pixel_swizzler_fuzzer', 'png_fuzzer', 'json_fuzzer', 'xz_fuzzer', 'jpeg_fuzzer']	[]

Directories in report

Directory
/usr/local/lib/clang/22/include/
/usr/local/bin/../include/c++/v1/
/src/wuffs/fuzz/c/std/../fuzzlib/
/src/wuffs/fuzz/c/std/
/src/wuffs/fuzz/c/std/../../../release/c/