pysymex 0.1.1a1

EDUCATIONAL PURPOSES ONLY: A symbolic execution engine for studying formal verification concepts. Not for production use.

pysymex

python symbolic execution and formal verification research engine

Bytecode-level path exploration for supported Python programs, backed by Z3 and explicit unknown, unsupported, inconclusive, and blocked states when a definite answer is not justified.

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[!WARNING] pysymex is an alpha research prototype for studying symbolic execution and formal verification concepts. It is not production verification software, a security audit substitute, or a guarantee that a target program is safe.

At a Glance

Area	Current focus
Execution model	CPython bytecode execution for Python 3.11 through 3.13
Reasoning engine	Z3-backed path constraints and feasibility checks
Result model	Definite issues only when the path is feasible; uncertainty remains explicit
Output formats	Text, JSON, Markdown, HTML, and SARIF
Primary interfaces	pysymex scan, pysymex analyze, pysymex verify, and Python APIs
Project phase	Alpha, research-oriented, closed to external pull requests

Install

Use Python 3.11 or newer.

pip install pysymex

For local development from this repository:

git clone https://github.com/darkoss1/pysymex.git
cd pysymex
uv sync

uv sync creates .venv and sets the shell activation prompt to the project name (pysymex). Prefer uv sync over bare uv venv for first-time setup.

Core runtime dependencies are pinned or constrained in pyproject.toml, including z3-solver, pydantic, immutables, rich, and psutil.

Quick Start

Scan a file:

pysymex scan mycode.py

Scan a directory recursively:

pysymex scan src/ -r

Generate SARIF for CI systems:

pysymex scan src/ -r --format sarif -o report.sarif

Analyze a specific function:

pysymex analyze mycode.py -f risky_divide --args x:int y:int

Run the benchmark command:

pysymex benchmark --format markdown

Command Map

Need	Interface
Scan a file or tree for supported issue patterns	pysymex scan PATH [-r]
Inspect one function with typed symbolic inputs	pysymex analyze FILE -f NAME --args x:int
Verify contract-decorated code	pysymex verify FILE -f NAME
Fail a CI job by severity and optionally write SARIF	pysymex check PATH --fail-on high --sarif report.sarif
Measure benchmark cases or compare baselines	pysymex benchmark [--case NAME]

Python API

import asyncio

from pysymex import analyze


def risky_divide(x: int, y: int) -> int:
    return x // y


result = asyncio.run(analyze(risky_divide, {"x": "int", "y": "int"}))

for issue in result.issues:
    print(issue.kind)
    print(issue.message)
    print(issue.get_counterexample())

Use the Python API when you want direct access to symbolic execution results. Use the CLI when you want scanner workflows, report files, or CI-friendly output.

Supported Inputs and Reports

Surface	Current support
Python versions	CPython 3.11, 3.12, and 3.13 bytecode families
CLI symbolic argument types	int, str, list, bool, and dict
Scan	Symbolic execution only (pysymex scan; static/pipeline modes removed)
Report formats	text, json, sarif, rich, html, and markdown
CI workflow	pysymex check for severity-gated exits; SARIF for external viewers
Sandbox boundary	Target loading can go through the sandbox bridge; denials remain visible

Result Semantics

pysymex should not turn uncertainty into success. A result can include definite issues, unsupported behavior, blocked execution, or inconclusive paths depending on what the engine can justify.

State	Meaning
Definite issue	A feasible path reaches a detector condition or runtime failure
No issue reported	No definite issue was found within the explored supported paths
Unsupported	The target used behavior outside the implemented semantic model
Unknown or inconclusive	Solver uncertainty, path limits, incomplete modeling, or other limits prevented a definite answer
Blocked	Isolation, import, sandbox, or environment policy prevented execution

Practical Boundaries

Boundary	What it means for users
Feasibility first	A definite bug report should correspond to a feasible path, not just a syntactic pattern
Bounded exploration	Timeouts, path limits, and iteration limits can leave reachable behavior unexplored
Model coverage	Builtins, stdlib calls, imports, and dynamic Python features are only as precise as their models
Solver uncertainty	Z3 unknown, timeouts, or encoding gaps must remain inconclusive instead of becoming success
Sandbox policy	Native isolation and sandbox bridge failures are blocked states, not proof that code is safe
Report confidence	JSON, SARIF, HTML, and Markdown change presentation, not the underlying certainty level

Detection Surface

The detector surface includes runtime failures and static or logical signals. Coverage depends on supported syntax, bytecode, models, path limits, and solver outcomes.

Family	Examples
Arithmetic	division by zero, modulo by zero, overflow
Containers	index error, key error, missing attributes, symbolic container access
Runtime state	unbound local, name error, type error, value error, none dereference
Control flow	assertion failure, unreachable code, infinite loop signals
Resources	resource leak patterns
Contracts	precondition, postcondition, and contract validation failures
Logical checks	contradictions, impossible branches, path-level inconsistencies

Architecture

pysymex/
  api/                  public Python API facade
  cli/                  command-line interface and formatters
  scanner/              file and directory scanning workflows
  execution/            symbolic VM, opcode dispatch, and execution strategies
  core/                 symbolic state, memory, solver, and shared types
  models/               builtin, stdlib, and runtime behavior models
  analysis/             detectors, scanner range checks, and higher-level analyses
  sandbox/              isolation-facing execution boundaries
  reporting/            text, JSON, Markdown, HTML, and SARIF report generation
  tracing/              Z3 and execution trace support

The important boundary is trust: execution, solver, scanner, model, sandbox, and reporting layers should keep unsupported or inconclusive behavior visible instead of silently treating it as a successful verification result.

Examples

The examples directory contains small, numbered scenarios:

File	Focus
01_basic_safety_guards.py	Basic guard patterns
02_common_runtime_bugs.py	Common runtime failures
03_hidden_branch_constraints.py	Nested branches found via symbolic scan
04_contract_verification.py	Contract checking
05_deep_path_loops.py	Loop and path-depth behavior
06_sandbox_security.py	Sandbox-oriented examples
07_symbolic_containers.py	Symbolic container behavior
08_exception_handling.py	Exception paths

Development

Use the locked uv workflow when possible:

uv sync
uv run ruff check pysymex tests
uv run pyright pysymex tests
uv run pytest

Run a focused test while iterating:

uv run pytest tests/unit/path/to/test_file.py -q

Run multi-version Docker validation through the one-click script:

python tests/docker.py -- -q

Documentation

Document	Purpose
docs/README.md	Documentation index and recommended read order
docs/API.md	Public Python API reference
docs/CLI.md	Command-line usage and examples
docs/LIMITATIONS.md	Supported scope, uncertainty states, and safety boundaries
docs/arch/README.md	Source-grounded architecture reference
docs/GLOSSARY.md	Terms used across the project

An automatically generated Code Wiki is also available for exploratory architecture browsing: deepwiki.com/darkoss1/pysymex/. Treat it as secondary material that may lag behind this repository.

Contribution Policy

pysymex is currently open source but closed to external pull requests during its alpha phase. Issues and bug reports are welcome through the repository issue tracker.

See CONTRIBUTING.md for the current policy.

License

pysymex is licensed under the AGPL-3.0-only.

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Research engine. Explicit uncertainty. Feasible bugs over optimistic claims.