Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/wasi-common/wasi-misc-tests/src/lib.rs

@@ -0,0 +1,25 @@
+pub mod utils;
+pub mod wasi_wrappers;
+
+use libc;
+use std::ffi::CString;
+use std::io;
+use wasi::wasi_unstable;
+
+pub fn open_scratch_directory(path: &str) -> Result<wasi_unstable::Fd, String> {
+    // Open the scratch directory.
+    let dir_fd: wasi_unstable::Fd = unsafe {
+        let cstr = CString::new(path.as_bytes()).unwrap();
+        libc::open(cstr.as_ptr(), libc::O_RDONLY | libc::O_DIRECTORY)
+    } as wasi_unstable::Fd;
+
+    if (dir_fd as std::os::raw::c_int) < 0 {
+        Err(format!(
+            "error opening scratch directory '{}': {}",
+            path,
+            io::Error::last_os_error()
+        ))
+    } else {
+        Ok(dir_fd)
+    }
+}