httm VS cxx

My projects and many projects include a THIRD-PARTY-LICENSES.html file when I distribute binaries. See: https://github.com/kimono-koans/httm/blob/master/third_party/LICENSES_THIRD_PARTY.html

The only real advantage I can think of with nested ZFS is that the files in the KVM would obviously be individual inodes in the nested ZFS filesystem and datasets, in addition to the one inode per virtual volume on the hypervisor (or zvol). This would allow for granular file management on the kvm and the use of tools like https://github.com/kimono-koans/httm which is like a command line time machine for ZFS.

> It's worth noting that copy_file_range is used by a lot of things.

Yes, but the trigger feature, block cloning, only landed in the latest 2.2 release. If you immediately hopped on 2.2, and used a system with lots copy_file_range and FICLONE use, yes, you may have a problem (like, as you note, on Gentoo, where this problem surfaced).

Most people were just hopping on the bandwagon. My distro ships 2.1.5, so I have a 6 month wait until this feature lands, so I was just building copy_file_range support into my ZFS apps, right before news of this bug hit.[0]

> There are other things required to trigger the bug that are a lot less common though.

Exactly. My guess is the incidence of this will exceedingly rare for the common user/small NAS user/etc. I've run a corruption detector[0], and what I've found mostly indicates false positives. Some are build artifact fingerprints, which I don't care about, and which were deleted with the next build. The ones with an extant file on another system, I confirmed were a diff match with the origin using `rsync -rincv` and whats on snapshots with `httm --map-aliases`. So far no positive matches.

[0]: https://github.com/kimono-koans/httm

cargo install --git https://github.com/kimono-koans/httm --branch clones strace -f -o stderr.txt -e ioctl -- httm -r -R ~/.zshenv

httm prints the size, date and corresponding locations of available unique versions (deduplicated by modify time and size) of files residing on snapshots, but can also be used interactively to select and restore files, even snapshot mounts by file! httm might change the way you use snapshots (because ZFS/BTRFS/NILFS2 aren't designed for finding for unique file versions) or the Time Machine concept (because httm is very fast!).

All btrfs snapshot tools can have different layouts. It's mostly a nightmare for any one tool to support. Although its not the tool you're looking for, FYI AFAIK httm supports all/most btrfs layouts, but it took more work than necessary to get there.

ZFS only option which requires super user privileges.

[0]: https://github.com/kimono-koans/httm/blob/master/httm.1

httm - Interactive, file-level Time Machine-like tool for ZFS/btrfs/nilfs2

There are cxx and autocxx, what else do you propose to do?

I would like to see a comparison of how this compares to Rust. In terms of interoperability it has Cxx (https://cxx.rs) to offer safe bindings to C++ but also has great support for Android, Linux and many other systems. You don't even need to hack together Windows bindings (as explained in the blog post) because Microsoft offers official bindings (https://crates.io/crates/windows). I'm not sure if I'd call it a superpower if any potential interoperability has to be written to be used (compared to it already being available). Or rather, in comparison to what is interoperability a Swift superpower? Certainly not C++ or C which can be used in a far wider set of targets.

We selected Qt as a cross-platform solution. The C++/Rust interface is the clunkiest and ugliest part of the application, and rather complex because some state is shared between several windows in the GUI and several threads in the backend, and any component might modify that state at any time, and updates have to be transmitted to the other components without introducing inconsistencies. Using cxx [1] helped a little, though.

The project began in 2020, and I'm not sure what I'd choose as a GUI framework today – definitely not Qt Widgets, though.

[1] https://cxx.rs/

If the build process for the C library isn't too involved I recommend using cxx bridge (https://cxx.rs/) and letting cargo handle the build and linking. cxx basically allows you to describe the bidirectional interface (although it sounds like you only need 1 direction, which is fine too) in Rust code and it provides a "good enough" API for compiling C code inside the build.rs file.

The tooling for the first kind -- calling Rust from another language -- is a bit less developed, and tends to rely on code generation that doesn't necessarily produce a natural C API. cbindgen, uniffi, cxx, and Diplomat all take this course.

I would like to utilize OMPL's functionality in Rust code, so I want to call into OMPL C++ code somehow in Rust. I've seen two (non-mutually-exclusive) options so far: - rust-cpp, which allows you to write C++ code in Rust within the cpp!() macro. - cxx, which allows you to define both sides of the FFI boundary manually (as opposed to bindgen's automatic generation).

I'm not sure how to do this in cxx; issues like https://github.com/dtolnay/cxx/issues/447 suggest that this isn't settled yet?

I use non-vendored dependencies for the Buck build in https://github.com/dtolnay/cxx.

There's also the cpp and cxx crates for doing C++/Rust interop, but they probably aren't appropriate to use in all cases. The C ABI is definitely the safest way to go unless you're really trying to marry Rust and C++ code bases, not just writing library bindings.

There's also cxx (can't vouch for it personally but it claims to make things a lot easier) https://github.com/dtolnay/cxx