cargo-valgrind

A cargo subcommand, that runs valgrind and collects its output in a helpful manner.

This command extends cargo with the capability to directly run valgrind on the executable (either a bin-crate or an example). The output of valgrind is then used to mark the binary as pass/fail.

This command should not be necessary for ordinary Rust programs, especially if you are only using safe Rust code. But if you do FFI-related stuff (either by simply using a FFI-binding crate or because you are developing a safe wrapper for such FFI bindings) it may be really helpful to check, whether the memory usages across the FFI borders are correct.

A typical mistake would be:

use std::ffi::CString;
use std::os::raw::c_char;

extern "C" {
    fn puts(s: *const c_char);
}

fn main() {
    let string = CString::new("Test").unwrap();

    let ptr = string.into_raw();
    unsafe { puts(ptr) };

    // unsafe { CString::from_raw(ptr) };
}

The memory of the variable string will never be freed. cargo valgrind detects it:

$ cargo valgrind
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
   Analyzing `target/debug/cstring`
Test
       Error Leaked 5 bytes
        Info at realloc (vg_replace_malloc.c:826)
             at realloc (alloc.rs:125)
             at realloc (alloc.rs:184)
             at reserve_internal<u8,alloc::alloc::Global> (raw_vec.rs:666)
             at reserve_exact<u8,alloc::alloc::Global> (raw_vec.rs:411)
             at reserve_exact<u8> (vec.rs:482)
             at std::ffi::c_str::CString::from_vec_unchecked (c_str.rs:355)
             at std::ffi::c_str::CString::_new (c_str.rs:330)
             at std::ffi::c_str::CString::new (c_str.rs:324)
             at cstring::main (main.rs:9)
             at std::rt::lang_start::{{closure}} (rt.rs:64)
             at {{closure}} (rt.rs:49)
             at std::panicking::try::do_call (panicking.rs:293)
             at __rust_maybe_catch_panic (lib.rs:85)
             at try<i32,closure> (panicking.rs:272)
             at catch_unwind<closure,i32> (panic.rs:394)
             at std::rt::lang_start_internal (rt.rs:48)
             at std::rt::lang_start (rt.rs:64)
             at main

Un-commenting the unsafe { CString::from_raw(ptr) }; re-takes the memory and frees it correctly. cargo valgrind will compile the binary for you and won't detect a leak, since there is no leak anymore.

Installation

Requirements

You need to have valgrind installed and in the PATH (you can test this by running valgrind --help in your shell).

You'll also need to have cargo installed and in the PATH, but since this is a cargo subcommand, you will almost certainly have it already installed.

Install the binary

Run the following command:

cargo install --git https://github.com/jfrimmel/cargo-valgrind