fix write to flush buffer; fix warnings

CHANGELOG.md

@@ -5,6 +5,7 @@ All PRs to the Wasmer repository must add to this file.
 Blocks of changes will separated by version increments.
 
 ## **[Unreleased]**
+- [#368](https://github.com/wasmerio/wasmer/pull/368) Fix issue with write buffering
 - [#343](https://github.com/wasmerio/wasmer/pull/343) Implement preopened files for WASI and fix aligment issue when accessing WASI memory
 - [#367](https://github.com/wasmerio/wasmer/pull/367) Add caching support to the LLVM backend.
 - [#366](https://github.com/wasmerio/wasmer/pull/366) Remove `UserTrapper` trait to fix [#365](https://github.com/wasmerio/wasmer/issues/365).

lib/wasi/src/state.rs

@@ -12,12 +12,13 @@ use std::{
     time::SystemTime,
 };
 use wasmer_runtime_core::debug;
-use zbox::{init_env as zbox_init_env, FileType, OpenOptions, Repo, RepoOpener};
+use zbox::init_env as zbox_init_env;
 
 pub const MAX_SYMLINKS: usize = 100;
 
 #[derive(Debug)]
 pub enum WasiFile {
+    #[allow(dead_code)]
     ZboxFile(zbox::File),
     HostFile(fs::File),
 }
@@ -236,7 +237,7 @@ impl WasiFs {
     fn get_inode(&mut self, path: &str) -> Option<Inode> {
         Some(match self.name_map.entry(path.to_string()) {
             Entry::Occupied(o) => *o.get(),
-            Entry::Vacant(v) => {
+            Entry::Vacant(_v) => {
                 return None;
                 // let file = if let Ok(file) = OpenOptions::new()
                 //     .read(true)

lib/wasi/src/syscalls/mod.rs

@@ -37,11 +37,15 @@ fn write_bytes<T: Write>(
         let bytes = iov_inner.buf.deref(memory, 0, iov_inner.buf_len)?;
         write_loc
             .write(&bytes.iter().map(|b_cell| b_cell.get()).collect::<Vec<u8>>())
-            .map_err(|_| __WASI_EIO)?;
+            .map_err(|_| {
+                write_loc.flush();
+                __WASI_EIO
+            })?;
 
         // TODO: handle failure more accurately
         bytes_written += iov_inner.buf_len;
     }
+    write_loc.flush();
     Ok(bytes_written)
 }