crabgrind

Valgrind Client Request interface for Rust programs

Summary

crabgrind is a small library that enables Rust programs to tap into Valgrind's tools and environment.

It exposes full set of Valgrind's client requests in Rust, manages the structure, type conversions and enforces static typing where possible.

Usage

Minimum Supported Rust Version: 1.64

First, add crabgrind to Cargo.toml

[dependencies]
crabgrind = "0.2"

Note: This crate is no_std and dependency free

Build Configuration

We need to build against local Valgrind installation to read C macro definition, constants, and supported requests.

The build script (build.rs) attempts to locate headers in this order:

1. Environment Variable: If VALGRIND_INCLUDE is set, it is used as the include path.
2. pkg-config: The system is queried via pkg-config.
3. Standard Paths: Using standard include paths.

If headers cannot be located, the crate compiles using dummy headers; any request will panic! at runtime.

Example

Use some of the Client Requests:

use crabgrind::valgrind::{running_mode, RunningMode};

fn main() {
    assert_eq!(
        running_mode(), RunningMode::Valgrind,
        ":~$ valgrind {}", std::env::current_exe().unwrap().display()
    );

    crabgrind::println!("Hey, Valgrind!");
}

And run under Valgrind

:~$ cargo build
:~$ valgrind ./target/debug/app

Features

If you need your builds to be free of Valgrind artifacts, enable the opt-out feature. This turns every request into no-op.

crabgrind = { version = "0.2", features = ["opt-out"] }

More Examples

• Valgrind: Deterministic regression testing(e.g. CI or unit tests)
• Callgrind: Profiling specific code blocks in isolation
• Callgrind: Clearing setup costs to isolate some operation
• Memcheck: Checking for memory leaks at runtime(e.g. CI or unit tests)
• Memcheck: Enforcing bounds in a custom allocator
• DHAT: Tracking data volumes
• DRD: Tracking races in a custom shared memory
• DRD: Tracing memory accesses over some memory

Implementation

Valgrind's client request mechanism is a C implementation detail, exposed strictly via C macros. Since Rust does not support C preprocessor, these macros cannot be used directly.

crabgrind wraps the foundational VALGRIND_DO_CLIENT_REQUEST_EXPR macro via FFI binding. All higher-level client requests are implemented in Rust on top of this binding.

The overhead per request, compared to using C macros directly is strictly the cost of a single function call.

The implementation is independent of any specific Valgrind version. Instead, mismatches between requests and local Valgrind instance are handled at compile-time in a zero-cost way for supported requests.

Runtime Safety

We are coupled to the Valgrind version present during compilation.

If a request is invoked at runtime that is unsupported by the active Valgrind instance (e.g. running under an older Valgrind), the call panics immediately, showing the version mismatch message and request requirements.

If your application is running without Valgrind, these requests execute as harmless machine code. They will not panic or segfault, and overhead is probably undetectable except in a tight loops.

License

crabgrind is distributed under MIT license.

Valgrind itself is a GPL2, however valgrind/*.h headers are distributed under a BSD-style license, so we can use them without worrying about license conflicts.