It looks to be the case that Rust's standard allocator, jemalloc, is
incompatible with sanitizers. The incompatibility, for whatever reason,
seems to cause segfaults at runtime when jemalloc is linked with
sanitizers.

Without actually trying to figure out what's going on here this commit
instead takes the hammer of "let's remove jemalloc when testing". The
`tor_allocate` crate now by default switches to the system allocator
(eventually this will want to be the tor allocator). Most crates then
link to `tor_allocate` ot pick this up, but the `smartlist` crate had to
manually switch to the system allocator in testing and the `external`
crate had to be sure to link to `tor_allocate`.

The final gotcha here is that this patch also switches to
unconditionally passing `--target` to Cargo. For weird and arcane
reasons passing `--target` with the host target of the compiler (which
Cargo otherwise uses as the default) is different than not passing
`--target` at all. This ensure that our custom `RUSTFLAGS` with
sanitizer options doesn't make its way into build scripts, just the
final testing artifacts.

 * FIXES #24659: https://bugs.torproject.org/24659

Once we need a PRNG, we'll likely want to change the dev-dependency on the rand
crate to be a real dependency, and use rand::SmallRng as our PRNG.

 * FIXES #24660: https://bugs.torproject.org/24660

Isis Lovecruft authored 7 years ago and Nick Mathewson committed 7 years ago

Requires the update/libc-0.2.39 branch from
https://github.com/isislovecruft/tor-rust-dependencies to be merged
first.

Allows an optional no-op for testing purposes

Sebastian Hahn authored 7 years ago and Nick Mathewson committed 7 years ago

This gives an indication in the log that Tor was built with Rust
support, as well as laying some groundwork for further string-returning
APIs to be converted to Rust