30 lines
1.8 KiB
Markdown
30 lines
1.8 KiB
Markdown
# Entry-Point Runtime — Java
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## Signals to gather
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- `argv0` equals `java` / `javaw` or resides under `*/bin/java`.
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- `-jar <app.jar>` argument with the jar present in the VFS.
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- Manifest metadata (`META-INF/MANIFEST.MF`) containing `Main-Class` or `Start-Class`.
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- Spring Boot layout (`BOOT-INF/**`).
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- Classpath form (`-cp/-classpath`) followed by a main class token.
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- Presence of an embedded JRE (`lib/modules`, `jre/bin/java`).
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- `JAVA_OPTS`, `JAVA_TOOL_OPTIONS`, or `JAVA_HOME` environment hints.
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- `EXPOSE` ports often associated with Java servers (`8080`, `8443`).
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## Implementation notes
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- Expand env variables before resolving jar/class paths (supports `${VAR}`, `${VAR:-default}`).
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- For classpath mode, open a subset of jars to corroborate `Main-Class`.
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- Track when the app is started through shell wrappers (`exec java -jar "$APP_JAR"`); ShellFlow should already collapse these.
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- Distinguish between installers (e.g., `java -version`) and actual app launches by checking for jar/class arguments.
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- When multiple jars/classes are possible, prefer manifest-backed artefacts but record alternates in evidence.
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## Evidence & scoring
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- Reward concrete artefacts (jar exists, manifest resolved).
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- Add evidence entries for each heuristic (`"MANIFEST Main-Class=com.example.Main"`, `"Spring Boot BOOT-INF detected"`).
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- Penalise missing artefacts or ambiguous classpaths.
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- Surface runtime-specific env/ports as supplementary clues, but keep their weight low to avoid false positives.
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## Edge cases
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- Launcher scripts that eventually run `java` — ensure ShellFlow surfaces the final command.
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- Multi-module fat jars: only expose the main entry jar in evidence; keep supporting jars as context.
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- Native image (`native-image` / GraalVM) should fall through to Go/Rust/C++ detectors when `java` binary is absent.
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