Function open_scratch_directory

crates/test-programs/src/preview1.rs:16–41

Opens a fresh file descriptor for `path` where `path` should be a preopened directory.

(path: &str)

/// Opens a fresh file descriptor for `path` where `path` should be a preopened
/// directory.
pub fn open_scratch_directory(path: &str) -> Result<wasip1::Fd, String> {
    unsafe {
        for i in 3.. {
            let stat = match wasip1::fd_prestat_get(i) {
                Ok(s) => s,
                Err(_) => break,
            };
            if stat.tag != wasip1::PREOPENTYPE_DIR.raw() {
                continue;
            }
            let mut dst = Vec::with_capacity(stat.u.dir.pr_name_len);
            if wasip1::fd_prestat_dir_name(i, dst.as_mut_ptr(), dst.capacity()).is_err() {
                continue;
            }
            dst.set_len(stat.u.dir.pr_name_len);
            if dst == path.as_bytes() {
                return Ok(
                    wasip1::path_open(i, 0, ".", wasip1::OFLAGS_DIRECTORY, 0, 0, 0)
                        .expect("failed to open dir"),
                );
            }
        }

        Err(format!("failed to find scratch dir"))
    }
}

pub unsafe fn create_file(dir_fd: wasip1::Fd, filename: &str) {
    unsafe {