snapdir for C/C++

cargo build --release                       # -> target/release/libsnapdir_ffi.a
cbindgen --config cbindgen.toml --crate snapdir-ffi --output snapdir.h .
g++ -std=c++20 app.cpp -I. -L. -lsnapdir_ffi -lpthread -ldl -lm -o app

#include <snapdir.hpp>
#include <iostream>

int main() {
    const std::string store = "file:///tmp/store";

    // Synchronous: the 64-char snapshot id and the full manifest.
    const std::string id = snapdir::id("./my-dir");
    snapdir::Manifest m = snapdir::manifest("./my-dir");
    for (const snapdir::ManifestEntry &e : m.entries) {
        // e.type (PathType), e.perm, e.checksum, e.size, e.path
    }
    // snapdir::id_from_manifest(m) == id

    // Options mirror the C ABI defaults.
    snapdir::ManifestOptions opts;
    opts.no_follow = true;                  // do not follow symlinks
    opts.exclude   = std::string("\\.tmp$"); // extended-regex exclusion

    // Async transfer ops.
    const std::string pushed = snapdir::push("./my-dir", store).get();  // <snapshot-id>
    snapdir::pull(pushed, store, "./restored").get();
    snapdir::fetch(pushed, store).get();    // fetch into the local catalog

    // Diff two stores; each ref follows the store@id convention
    // (the last '@' splits the store URI from the 64-hex id).
    std::vector<snapdir::DiffEntry> changes =
        snapdir::diff("file:///tmp/store-a", "file:///tmp/store-b").get();
    for (const auto &e : changes) {
        // e.status is one of A / D / M / = ; e.path is the entry path
        std::cout << static_cast<char>(e.status) << '\t' << e.path << '\n';
    }
}

try {
    auto id = snapdir::id("/no/such/path");
} catch (const snapdir::Error &e) {
    // e.code() is one of: IO_ERROR, HASH_MISMATCH, STORE_ERROR, IN_FLUX,
    // CATALOG_ERROR, INVALID_ID, INVALID_STORE, CONFLICT.
    std::fprintf(stderr, "snapdir error [%s]: %s\n", e.code().c_str(), e.what());
}