libxml-rs

Phase 1: Compatibility Skeleton — C ABI drop-in skeleton verified.

Custodial native-Rust reimplementation of the libxml2 + libxslt ecosystem: a forensic reconstruction of observable behavior, implemented in native Rust, with C ABI compatibility for drop-in replacement.

This is not an XML crate. This is not an XSLT crate. This is not a wrapper. This is a custodial forensic archive and native-Rust reimplementation of the complete observable behavior of libxml2 and libxslt across their historical lifetimes.

Current Status: Phase 1 — Compatibility Skeleton (§85)

Phase 1 establishes the C ABI compatibility skeleton: the structural and linker-level foundations necessary before any parser implementation begins. Per §85:

Deliverable: Existing trivial C consumers compile and load the Rust artifacts.

What exists now

• Single Cargo package: One crate with deeply organized module tree matching upstream subsystem boundaries
• C headers (45 libxml + 19 libxslt): Compatible C headers in include/ — compile with both gcc and g++, strict warning flags, zero warnings
• ABI exports: 211 libxml2 + 26 libxslt #[no_mangle] extern "C" symbols exported from liblibxml_rs.so
• SONAME symlinks: libxml2.so.2.12.0, libxslt.so.1.1.39 with full symlink chain — -lxml2 and -lxslt link correctly
• pkg-config: libxml-2.0.pc and libxslt.pc generated by build.rs
• Config scripts: xml2-config and xslt-config shell scripts
• Tree implementation: Complete xmlNode, xmlDoc, xmlAttr, xmlNs, xmlDtd with create/free/copy/link/unlink/replace — 16 tree tests
• Dictionary: FNV-1a hashed dictionary with create/lookup/copy/free — 8 tests
• Hash table: Full hash table implementation — 10 tests
• List: Doubly-linked list with push/pop/insert/delete/search/sort — 9 tests
• Memory hooks: Allocator replacement infrastructure with parking_lot::RwLock
• Error subsystem: Error stack with domains/codes/levels, structured error handling
• Globals/Threads: Library initialization, cleanup, thread-local state
• Versioning: xmlParserVersion, xmlLibVersion, LIBXML_TEST_VERSION macros
• Docker oracle: Reproducible libxml2 2.12.0 / libxslt 1.1.39 build (Debian bookworm)
• ABI courts: 6/6 passing — struct layout, symbol enumeration, enum value verification — against both candidate headers and oracle
• 62 passing tests: cargo test --lib — 0 failures, 0 errors

What does NOT exist yet

• No XML parser (Phase 2)
• No SAX callback dispatching (Phase 2)
• No XPath engine (Phase 5)
• No XSLT engine (Phase 8)
• No CLI tools (Phase 10)
• No validation (Phase 6)
• 211 exported symbols are stubs returning NULL/0 — function bodies implemented progressively in Phases 2–10

Build

cargo build                          # Build library + CLI stubs
cargo build --lib                    # Build only the library
cargo test --lib                     # Run library tests (62 passing)

# Test C consumer compilation against our headers:
gcc -I include courts/suites/sanity/ABI-STRUCT-NODE-0001-abicheck.c -o /tmp/abicheck
clang -I include courts/suites/sanity/ABI-ENUM-0001-enumcheck.c -o /tmp/enumcheck

# Build and run oracle container:
docker build -f docker/Dockerfile.oracle -t libxml-rs/oracle:2.12.0 docker/

Oracle verification

The oracle Docker container builds libxml2 2.12.0 and libxslt 1.1.39 from source. All ABI courts pass against the oracle. The candidate (libxml-rs) does not link against system libxml2/libxslt — verified by oracle contamination court.

Project Structure

libxml-rs/
├── Cargo.toml              # Single Cargo package (no workspace)
├── src/
│   ├── lib.rs              # Library entry point
│   ├── abi/                # C ABI compatibility layer (§4, §14)
│   ├── xml/                # libxml2 implementation (§1, §3, §31)
│   ├── xslt/               # libxslt implementation (§31–§34)
│   ├── exslt/              # EXSLT modules (§35)
│   ├── compatibility/      # Historical profiles, quirks, platform (§68, §69)
│   └── bin/                # CLI tools: xmllint, xmlcatalog, xsltproc (§36)
├── include/                # Compatible C headers (§15)
├── atlas/                  # Forensic archive (§7–§12)
│   ├── releases/           # Release manifests per version
│   ├── api/                # Public API inventories
│   ├── abi/                # ABI snapshots
│   ├── symbols/            # Symbol table comparisons
│   ├── config/             # Build configuration profiles
│   ├── standards/          # Standards mapping
│   ├── HISTORY.md          # Complete release history
│   ├── LORE.md             # Undocumented behavior archive
│   ├── QUIRKS.md           # Confirmed compatibility quirks
│   ├── PARITY_MATRIX.md    # Current parity status
│   ├── RESIDUAL_LEDGER.md  # Unexplained differences
│   └── SECURITY_HISTORY.md # Vulnerability custody
├── oracle/                 # Reproducible upstream build environment (§39)
├── courts/                 # Differential testing framework (§40–§50)
│   ├── schema.json         # Casefile schema
│   ├── suites/             # Court case suites
│   ├── receipts/           # Execution receipts
│   └── tools/              # Court runner
├── tools/                  # Archaeology and analysis tooling
│   ├── archaeology/        # manifest.py, apiatlas.py, symbols.py, delta.py, profileconfig.py
│   └── courts/             # Court runner
├── docker/                 # Reproducible Docker oracle images
├── docs/                   # Technical documentation
└── archaeology/            # Upstream git clones (immutable, offline)

Build

cargo build              # Build the library
cargo build --lib        # Build only the library (not CLI stubs)
cargo test               # Run tests (Phase 0: limited)

License

Licensed under either of:

• MIT license (LICENSE-MIT)
• Apache License, Version 2.0 (LICENSE-APACHE)

at your option.

Project Status

See atlas/PARITY_MATRIX.md for the detailed, evidence-bounded parity matrix.