61 lines
2.1 KiB
Python
61 lines
2.1 KiB
Python
"""AST-level resource leak injection for JavaScript using esprima."""
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from typing import Optional
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import esprima
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from app.dataset.rules.base import Mutation, MutationRule
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class JSResourceLeakRule(MutationRule):
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"""Remove a fetch Response body close/usage, leaking the reader.
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Uses `esprima` to locate a `try/finally` that closes a reader and removes
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the finally block.
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"""
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name = "js_resource_leak"
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language = "javascript"
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defect_type = "resource_not_closed"
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def detect_and_mutate(self, source: str, filename: str = "") -> Optional[Mutation]:
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# Modern JS is usually ESM: try module grammar first, then script.
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try:
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tree = esprima.parseModule(source, loc=True)
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except Exception:
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try:
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tree = esprima.parseScript(source, loc=True)
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except Exception:
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return None
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def walk(node):
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yield node
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for key in node.__dict__:
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child = getattr(node, key)
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if isinstance(child, list):
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for item in child:
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if hasattr(item, "type"):
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yield from walk(item)
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elif hasattr(child, "type"):
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yield from walk(child)
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for node in walk(tree):
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if node.type != "TryStatement" or not node.finalizer:
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continue
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start = node.loc.start.line
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end = node.finalizer.loc.end.line
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lines = source.splitlines(keepends=True)
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# Drop the finally block entirely, close the try block
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finally_start = node.finalizer.loc.start.line - 1
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mutated = "".join(lines[:finally_start] + [" }\n"] + lines[end:])
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return Mutation(
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defect_type=self.defect_type,
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language=self.language,
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line_start=start,
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line_end=end,
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mutated_source=mutated,
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reference_fix="Restore finally block to close/release resources.",
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description="Removed finally block, leaving resource unreleased.",
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)
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return None
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