[llvm] [libfuzzer][docs] Update and clarify Output section (PR #125075)
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Fri Jan 31 01:24:37 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-compiler-rt-sanitizer
Author: Paweł Bylica (chfast)
<details>
<summary>Changes</summary>
In the documentation page for the libfuzzer update the example snippets of outputs. They are now slightly different than what is documented.
Improve the documentation of the output section `L:`. It now shows two numbers.
Closes https://github.com/llvm/llvm-project/issues/42571.
---
Full diff: https://github.com/llvm/llvm-project/pull/125075.diff
1 Files Affected:
- (modified) llvm/docs/LibFuzzer.rst (+32-22)
``````````diff
diff --git a/llvm/docs/LibFuzzer.rst b/llvm/docs/LibFuzzer.rst
index 9e34530e7e3e78..2137740896ddb2 100644
--- a/llvm/docs/LibFuzzer.rst
+++ b/llvm/docs/LibFuzzer.rst
@@ -354,16 +354,18 @@ Output
During operation the fuzzer prints information to ``stderr``, for example::
- INFO: Seed: 1523017872
- INFO: Loaded 1 modules (16 guards): [0x744e60, 0x744ea0),
- INFO: -max_len is not provided, using 64
+ INFO: Running with entropic power schedule (0xFF, 100).
+ INFO: Seed: 1434179311
+ INFO: Loaded 1 modules (8 inline 8-bit counters): 8 [0x5f03d189be90, 0x5f03d189be98),
+ INFO: Loaded 1 PC tables (8 PCs): 8 [0x5f03d189be98,0x5f03d189bf18),
+ INFO: -max_len is not provided; libFuzzer will not generate inputs larger than 4096 bytes
INFO: A corpus is not provided, starting from an empty corpus
- #0 READ units: 1
- #1 INITED cov: 3 ft: 2 corp: 1/1b exec/s: 0 rss: 24Mb
- #3811 NEW cov: 4 ft: 3 corp: 2/2b exec/s: 0 rss: 25Mb L: 1 MS: 5 ChangeBit-ChangeByte-ChangeBit-ShuffleBytes-ChangeByte-
- #3827 NEW cov: 5 ft: 4 corp: 3/4b exec/s: 0 rss: 25Mb L: 2 MS: 1 CopyPart-
- #3963 NEW cov: 6 ft: 5 corp: 4/6b exec/s: 0 rss: 25Mb L: 2 MS: 2 ShuffleBytes-ChangeBit-
- #4167 NEW cov: 7 ft: 6 corp: 5/9b exec/s: 0 rss: 25Mb L: 3 MS: 1 InsertByte-
+ #2 INITED cov: 2 ft: 2 corp: 1/1b exec/s: 0 rss: 31Mb
+ #144 NEW cov: 3 ft: 3 corp: 2/2b lim: 4 exec/s: 0 rss: 31Mb L: 1/1 MS: 2 ChangeByte-ChangeByte-
+ #157 NEW cov: 4 ft: 4 corp: 3/4b lim: 4 exec/s: 0 rss: 31Mb L: 2/2 MS: 3 CrossOver-ChangeBit-CrossOver-
+ #1345 NEW cov: 5 ft: 5 corp: 4/8b lim: 14 exec/s: 0 rss: 32Mb L: 4/4 MS: 3 InsertByte-ChangeBit-CrossOver-
+ #1696 NEW cov: 6 ft: 6 corp: 5/10b lim: 17 exec/s: 0 rss: 32Mb L: 2/4 MS: 1 EraseBytes-
+ #1832 REDUCE cov: 6 ft: 6 corp: 5/9b lim: 17 exec/s: 0 rss: 32Mb L: 3/3 MS: 1 EraseBytes-
...
The early parts of the output include information about the fuzzer options and
@@ -407,7 +409,7 @@ Each output line also reports the following statistics (when non-zero):
``corp:``
Number of entries in the current in-memory test corpus and its size in bytes.
``lim:``
- Current limit on the length of new entries in the corpus. Increases over time
+ Current limit on the length of new entries in the corpus. Increases over time
until the max length (``-max_len``) is reached.
``exec/s:``
Number of fuzzer iterations per second.
@@ -418,7 +420,8 @@ For ``NEW`` and ``REDUCE`` events, the output line also includes information
about the mutation operation that produced the new input:
``L:``
- Size of the new input in bytes.
+ Size of the new/reduced input in bytes and the size of the largest input
+ in current in-memory test corpus.
``MS: <n> <operations>``
Count and list of the mutation operations used to generate the input.
@@ -453,19 +456,26 @@ A simple function that does something interesting if it receives the input
You should get an error pretty quickly::
- INFO: Seed: 1523017872
- INFO: Loaded 1 modules (16 guards): [0x744e60, 0x744ea0),
- INFO: -max_len is not provided, using 64
+ INFO: Running with entropic power schedule (0xFF, 100).
+ INFO: Seed: 1434179311
+ INFO: Loaded 1 modules (8 inline 8-bit counters): 8 [0x5f03d189be90, 0x5f03d189be98),
+ INFO: Loaded 1 PC tables (8 PCs): 8 [0x5f03d189be98,0x5f03d189bf18),
+ INFO: -max_len is not provided; libFuzzer will not generate inputs larger than 4096 bytes
INFO: A corpus is not provided, starting from an empty corpus
- #0 READ units: 1
- #1 INITED cov: 3 ft: 2 corp: 1/1b exec/s: 0 rss: 24Mb
- #3811 NEW cov: 4 ft: 3 corp: 2/2b exec/s: 0 rss: 25Mb L: 1 MS: 5 ChangeBit-ChangeByte-ChangeBit-ShuffleBytes-ChangeByte-
- #3827 NEW cov: 5 ft: 4 corp: 3/4b exec/s: 0 rss: 25Mb L: 2 MS: 1 CopyPart-
- #3963 NEW cov: 6 ft: 5 corp: 4/6b exec/s: 0 rss: 25Mb L: 2 MS: 2 ShuffleBytes-ChangeBit-
- #4167 NEW cov: 7 ft: 6 corp: 5/9b exec/s: 0 rss: 25Mb L: 3 MS: 1 InsertByte-
- ==31511== ERROR: libFuzzer: deadly signal
+ #2 INITED cov: 2 ft: 2 corp: 1/1b exec/s: 0 rss: 31Mb
+ #144 NEW cov: 3 ft: 3 corp: 2/2b lim: 4 exec/s: 0 rss: 31Mb L: 1/1 MS: 2 ChangeByte-ChangeByte-
+ #157 NEW cov: 4 ft: 4 corp: 3/4b lim: 4 exec/s: 0 rss: 31Mb L: 2/2 MS: 3 CrossOver-ChangeBit-CrossOver-
+ #1345 NEW cov: 5 ft: 5 corp: 4/8b lim: 14 exec/s: 0 rss: 32Mb L: 4/4 MS: 3 InsertByte-ChangeBit-CrossOver-
+ #1696 NEW cov: 6 ft: 6 corp: 5/10b lim: 17 exec/s: 0 rss: 32Mb L: 2/4 MS: 1 EraseBytes-
+ #1832 REDUCE cov: 6 ft: 6 corp: 5/9b lim: 17 exec/s: 0 rss: 32Mb L: 3/3 MS: 1 EraseBytes-
+ ==840148== ERROR: libFuzzer: deadly signal
...
- artifact_prefix='./'; Test unit written to ./crash-b13e8756b13a00cf168300179061fb4b91fefbed
+ SUMMARY: libFuzzer: deadly signal
+ MS: 2 CopyPart-ChangeByte-; base unit: dbee5f8c7a5da845446e75b4a5708e74428b520a
+ 0x48,0x49,0x21,
+ HI!
+ artifact_prefix='./'; Test unit written to ./crash-7a8dc3985d2a90fb6e62e94910fc11d31949c348
+ Base64: SEkh
More examples
``````````
</details>
https://github.com/llvm/llvm-project/pull/125075
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