layout-audit

Detect memory layout inefficiencies in C/C++/Rust/Go binaries.

layout-audit reads DWARF debug info to visualize struct layouts, find padding, and flag cache-inefficient layouts. Great for catching regressions in CI.

Install

• cargo install layout-audit
• Or download a prebuilt binary from GitHub Releases.

Quick start

# Inspect all structs
layout-audit inspect ./target/debug/myapp

# JSON output
layout-audit inspect ./target/debug/myapp -o json

# SARIF output (for GitHub code scanning)
layout-audit inspect ./target/debug/myapp -o sarif > layout-audit.sarif

Commands

• inspect — analyze struct layouts
• diff — compare two binaries (use --fail-on-regression in CI)
• check — enforce budgets from a config file
• suggest — propose field reordering (review for ABI/serialization impact)

Budget config (.layout-audit.yaml)

budgets:
  Order:
    max_size: 64
    max_padding: 8
    max_padding_percent: 15.0

  "hot_path::*":
    max_padding_percent: 5.0

  "*":
    max_size: 256

GitHub Action

Basic usage:

- uses: avifenesh/layout-audit@v0.5.0
  with:
    binary: ./target/debug/myapp
    command: inspect

SARIF (GitHub code scanning). The action uploads SARIF automatically when output: sarif is set. Your workflow must grant security-events: write.

permissions:
  security-events: write

- uses: avifenesh/layout-audit@v0.5.0
  with:
    command: diff
    binary: ./target/debug/myapp
    baseline: ./target/debug/myapp-baseline
    output: sarif

Action inputs

Input	Description	Default
binary	Path to binary file (required)	-
command	inspect, diff, check, or suggest	inspect
baseline	Baseline binary for diff	-
config	Config file for check	.layout-audit.yaml
filter	Filter structs by name	-
output	Output format: table, json, or sarif	table
sort-by	Sort by: name, size, padding, padding-pct	padding
top	Show only top N structs	-
min-padding	Minimum padding bytes to show	-
min-savings	Minimum savings bytes to show (suggest)	-
sort-by-savings	Sort suggestions by savings (suggest)	false
fail-on-regression	Fail if layout regressed (diff)	false
version	layout-audit version to use	latest

Action outputs

Output	Description
report	The layout-audit output
sarif-path	Path to SARIF file (when output: sarif)

Requirements

• Rust 1.85+
• Binaries must include DWARF debug info (-g)
• Formats: ELF (Linux), Mach-O (macOS), PE (Windows with MinGW)
• On macOS, pass the dSYM path: ./binary.dSYM/Contents/Resources/DWARF/binary

Go notes

Go is supported on Linux/macOS (Windows uses PDB). Use full debug info:

go build -gcflags=all="-N -l" -o myapp

Runtime types are filtered by default; use --include-go-runtime to show them.

License

MIT OR Apache-2.0