Try #554:

lib/wasi-tests/build/wasitests.rs

@@ -32,7 +32,6 @@ pub fn compile(file: &str, ignores: &HashSet<String>) -> Option<String> {
     };
 
     Command::new("rustc")
-        .arg("+nightly")
         .arg(file)
         .arg("-o")
         .arg(&normalized_name)

lib/wasi-tests/tests/wasitests/_common.rs

@@ -54,10 +54,9 @@ macro_rules! assert_wasi_output {
         let expected_output = include_str!($expected);
 
         assert!(
-            output.contains(expected_output),
+            assert_cond,
             "Output: `{}` does not contain expected output: `{}`",
-            output,
-            expected_output
+            output, expected_output
         );
     }};
 }

lib/wasi-tests/tests/wasitests/fseek.rs

@@ -0,0 +1,10 @@
+#[test]
+fn test_fseek() {
+    assert_wasi_output!(
+        "../../wasitests/fseek.wasm",
+        "fseek",
+        vec![],
+        vec![],
+        "../../wasitests/fseek.out"
+    );
+}

lib/wasi-tests/tests/wasitests/mod.rs

@@ -9,6 +9,7 @@ mod create_dir;
 mod envvar;
 mod file_metadata;
 mod fs_sandbox_test;
+mod fseek;
 mod hello;
 mod mapdir;
 mod quine;

lib/wasi-tests/wasitests/fseek.out

@@ -0,0 +1,11 @@
+SCENE III. A room in Polonius' h
+ouse.
+
+    Enter LAERTES and OPH
+    And, sister, as the winds gi
+r talk with the Lord Hamlet.
+
+uits,
+    Breathing like sanctif
+is is for all:
+    I would not, 

lib/wasi-tests/wasitests/fseek.rs

@@ -0,0 +1,47 @@
+// Args:
+// mapdir: .:wasitests/test_fs/hamlet
+
+use std::fs;
+use std::io::{Read, Seek, SeekFrom};
+use std::path::PathBuf;
+
+fn main() {
+    #[cfg(not(target_os = "wasi"))]
+    let mut base = PathBuf::from("wasitests/test_fs/hamlet");
+    #[cfg(target_os = "wasi")]
+    let mut base = PathBuf::from(".");
+
+    base.push("act1/scene3.txt");
+
+    let mut file = fs::File::open(&base).expect("Could not open file");
+
+    let mut buffer = [0u8; 32];
+
+    assert_eq!(file.read(&mut buffer).unwrap(), 32);
+    let str_val = std::str::from_utf8(&buffer[..]).unwrap();
+    println!("{}", str_val);
+
+    assert_eq!(file.read(&mut buffer).unwrap(), 32);
+    let str_val = std::str::from_utf8(&buffer[..]).unwrap();
+    println!("{}", str_val);
+
+    assert_eq!(file.seek(SeekFrom::Start(123)).unwrap(), 123);
+    assert_eq!(file.read(&mut buffer).unwrap(), 32);
+    let str_val = std::str::from_utf8(&buffer[..]).unwrap();
+    println!("{}", str_val);
+
+    assert_eq!(file.seek(SeekFrom::End(-123)).unwrap(), 6617);
+    assert_eq!(file.read(&mut buffer).unwrap(), 32);
+    let str_val = std::str::from_utf8(&buffer[..]).unwrap();
+    println!("{}", str_val);
+
+    assert_eq!(file.seek(SeekFrom::Current(-250)).unwrap(), 6399);
+    assert_eq!(file.read(&mut buffer).unwrap(), 32);
+    let str_val = std::str::from_utf8(&buffer[..]).unwrap();
+    println!("{}", str_val);
+
+    assert_eq!(file.seek(SeekFrom::Current(50)).unwrap(), 6481);
+    assert_eq!(file.read(&mut buffer).unwrap(), 32);
+    let str_val = std::str::from_utf8(&buffer[..]).unwrap();
+    println!("{}", str_val);
+}

lib/wasi-tests/wasitests/mapdir.rs

@@ -4,9 +4,9 @@
 use std::fs;
 
 fn main() {
-    #[cfg(not(target = "wasi"))]
+    #[cfg(not(target_os = "wasi"))]
     let read_dir = fs::read_dir("wasitests/test_fs/hamlet").unwrap();
-    #[cfg(target = "wasi")]
+    #[cfg(target_os = "wasi")]
     let read_dir = fs::read_dir(".").unwrap();
     let mut out = vec![];
     for entry in read_dir {

lib/wasi/src/syscalls/mod.rs

@@ -903,7 +903,28 @@ pub fn fd_seek(
     // TODO: handle case if fd is a dir?
     match whence {
         __WASI_WHENCE_CUR => fd_entry.offset = (fd_entry.offset as i64 + offset) as u64,
-        __WASI_WHENCE_END => unimplemented!("__WASI__WHENCE_END in wasi::fd_seek"),
+        __WASI_WHENCE_END => {
+            use std::io::SeekFrom;
+            match state.fs.inodes[fd_entry.inode].kind {
+                Kind::File { ref mut handle } => {
+                    let end = wasi_try!(handle.seek(SeekFrom::End(0)).ok().ok_or(__WASI_EIO));
+                    // TODO: handle case if fd_entry.offset uses 64 bits of a u64
+                    fd_entry.offset = (end as i64 + offset) as u64;
+                }
+                Kind::Symlink { .. } => {
+                    unimplemented!("wasi::fd_seek not implemented for symlinks")
+                }
+                Kind::Dir { .. } => {
+                    // TODO: check this
+                    return __WASI_EINVAL;
+                }
+                Kind::Buffer { .. } => {
+                    // seeking buffers probably makes sense
+                    // TODO: implement this
+                    return __WASI_EINVAL;
+                }
+            }
+        }
         __WASI_WHENCE_SET => fd_entry.offset = offset as u64,
         _ => return __WASI_EINVAL,
     }
@@ -1235,6 +1256,7 @@ pub fn path_filestat_get(
             let last_segment = path_vec.last().unwrap();
             cumulative_path.push(last_segment);
 
+            // read it from wasi FS cache first, otherwise check host system
             if entries.contains_key(last_segment) {
                 state.fs.inodes[entries[last_segment]].stat
             } else {
@@ -1244,7 +1266,25 @@ pub fn path_filestat_get(
                 }
                 let final_path_metadata =
                     wasi_try!(cumulative_path.metadata().map_err(|_| __WASI_EIO));
-                wasi_try!(get_stat_for_kind(&state.fs.inodes[inode].kind).ok_or(__WASI_EIO))
+                let kind = if final_path_metadata.is_file() {
+                    let file =
+                        wasi_try!(std::fs::File::open(&cumulative_path).ok().ok_or(__WASI_EIO));
+                    Kind::File {
+                        handle: WasiFile::HostFile(file),
+                    }
+                } else if final_path_metadata.is_dir() {
+                    Kind::Dir {
+                        parent: Some(inode),
+                        // TODO: verify that this doesn't cause issues with relative paths
+                        path: cumulative_path.clone(),
+                        entries: Default::default(),
+                    }
+                } else {
+                    // TODO: check this
+                    return __WASI_EINVAL;
+                };
+
+                wasi_try!(get_stat_for_kind(&kind).ok_or(__WASI_EIO))
             }
         }
         _ => {