programming-rust-examples/libgit2-rs/src/main.rs

#![warn(rust_2018_idioms)]
#![allow(elided_lifetimes_in_paths)]

mod raw;

use std::ffi::CStr;
use std::os::raw::c_int;

fn check(activity: &'static str, status: c_int) -> c_int {
    if status < 0 {
        unsafe {
            let error = &*raw::giterr_last();
            println!("error while {}: {} ({})",
                     activity,
                     CStr::from_ptr(error.message).to_string_lossy(),
                     error.klass);
            std::process::exit(1);
        }
    }

    status
}

unsafe fn show_commit(commit: *const raw::git_commit) {
    let author = raw::git_commit_author(commit);

    let name = CStr::from_ptr((*author).name).to_string_lossy();
    let email = CStr::from_ptr((*author).email).to_string_lossy();
    println!("{} <{}>\n", name, email);

    let message = raw::git_commit_message(commit);
    println!("{}", CStr::from_ptr(message).to_string_lossy());
}

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

fn main() {
    let path = std::env::args().skip(1).next()
        .expect("usage: git-toy PATH");
    let path = CString::new(path)
        .expect("path contains null characters");

    unsafe {
        check("initializing library", raw::git_libgit2_init());

        let mut repo = ptr::null_mut();
        check("opening repository",
              raw::git_repository_open(&mut repo, path.as_ptr()));

        let c_name = b"HEAD\0".as_ptr() as *const c_char;
        let oid = {
            let mut oid = mem::MaybeUninit::uninit();
            check("looking up HEAD",
                  raw::git_reference_name_to_id(oid.as_mut_ptr(), repo, c_name));
            oid.assume_init()
        };

        let mut commit = ptr::null_mut();
        check("looking up commit",
              raw::git_commit_lookup(&mut commit, repo, &oid));

        show_commit(commit);

        raw::git_commit_free(commit);

        raw::git_repository_free(repo);

        check("shutting down library", raw::git_libgit2_shutdown());
    }
}