Fix: disable custom hooks during coverage report generation

[kyakdan]

Fixes #878

[Copilot]

Pull request overview

This PR fixes issue #878 where custom hooks are not properly disabled during coverage report generation, causing NoClassDefFoundError when hooked classes are used during coverage dumping and the hook class is no longer loadable.

Changes:

• Enable conditional hooks automatically when custom user hooks are used with coverage reporting
• Disable hooks before generating coverage reports in the shutdown sequence
• Add regression test to verify hooks are disabled during coverage report generation

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/main/java/com/code_intelligence/jazzer/agent/Agent.kt	Automatically enables conditional hooks when user hooks are used with coverage reporting to allow runtime hook disabling
src/main/java/com/code_intelligence/jazzer/driver/FuzzTargetRunner.java	Disables hooks before coverage dump/report generation in shutdown sequence
src/main/java/com/code_intelligence/jazzer/driver/Opt.java	Updates comment to document that conditional hooks are used during coverage report generation
tests/src/test/java/com/example/CoverageWithHooksFuzzer.java	Regression test verifying hooks are disabled during coverage generation
tests/src/test/java/com/example/CoverageWithHooksFuzzerHooks.java	Custom hook for regression test that sets system property when called
tests/BUILD.bazel	Test configuration for the regression test with custom hook JAR

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.

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[oetr]

It's interesting that you can alternatively also "fix" this issue by disabling our RegexRoadblocks sanitizer: --disabled_hooks=com.code_intelligence.jazzer.sanitizers.RegexRoadblocks.
I am still looking into this..

Edit: The issue exists only in Jazzer standalone, and not in the JUnit integration code path.

[oetr]

LGTM !

Ideally, Jazzer should internally not use any classes that we instrument. For example, Jazzer internally uses java.util.regex.Pattern that is instrumented by RegexRoadblocks.

It would be nice if we could keep original functions, and force all internall Jazzer dependencies to use the original functions.

But your fix is good enough!