implement wasi::path_rename

CHANGELOG.md

@@ -8,6 +8,7 @@ Blocks of changes will separated by version increments.
 
 Special thanks to @YaronWittenstein @penberg for their contributions.
 
+- [#650](https://github.com/wasmerio/wasmer/issues/650) Implement `wasi::path_rename`, improve WASI FS public api, and allow open files to exist even when the underlying file is deleted
 - [#643](https://github.com/wasmerio/wasmer/issues/643) Implement `wasi::path_symlink` and improve WASI FS public api IO error reporting
 - [#608](https://github.com/wasmerio/wasmer/issues/608) Implement wasi syscalls `fd_allocate`, `fd_sync`, `fd_pread`, `path_link`, `path_filestat_set_times`; update WASI fs API in a WIP way; reduce coupling of WASI code to host filesystem; make debug messages from WASI more readable; improve rights-checking when calling syscalls; implement reference counting on inodes; misc bug fixes and improvements
 - [#616](https://github.com/wasmerio/wasmer/issues/616) Create the import object separately from instance instantiation in `runtime-c-api`

Makefile

@@ -7,7 +7,7 @@ generate-spectests:
 generate-emtests:
 	WASM_EMSCRIPTEN_GENERATE_EMTESTS=1 cargo build -p wasmer-emscripten-tests --release
 
-generate-wasitests:
+generate-wasitests: wasitests-setup
 	WASM_WASI_GENERATE_WASITESTS=1 cargo build -p wasmer-wasi-tests --release -vv \
 	&& echo "formatting" \
 	&& cargo fmt

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

@@ -16,6 +16,7 @@ mod fseek;
 mod hello;
 mod mapdir;
 mod path_link;
+mod path_rename;
 mod path_symlink;
 mod quine;
 mod readlink;

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

@@ -0,0 +1,14 @@
+#[test]
+fn test_path_rename() {
+    assert_wasi_output!(
+        "../../wasitests/path_rename.wasm",
+        "path_rename",
+        vec![],
+        vec![(
+            "temp".to_string(),
+            ::std::path::PathBuf::from("wasitests/test_fs/temp")
+        ),],
+        vec![],
+        "../../wasitests/path_rename.out"
+    );
+}

lib/wasi-tests/wasitests/path_rename.out

@@ -0,0 +1,2 @@
+The original file does not still exist!
+柴犬

lib/wasi-tests/wasitests/path_rename.rs

@@ -0,0 +1,56 @@
+// Args:
+// mapdir: temp:wasitests/test_fs/temp
+
+use std::fs;
+use std::io::{Read, Write};
+use std::path::PathBuf;
+
+fn main() {
+    #[cfg(not(target_os = "wasi"))]
+    let mut base = PathBuf::from("wasitests/test_fs");
+    #[cfg(target_os = "wasi")]
+    let mut base = PathBuf::from("/");
+
+    let file_to_create = base.join("temp/path_rename_file.txt");
+    let file_to_rename_to = base.join("temp/path_renamed_file.txt");
+
+    {
+        let mut f = std::fs::OpenOptions::new()
+            .create_new(true)
+            .write(true)
+            .open(&file_to_create)
+            .unwrap();
+
+        // text from https://ja.wikipedia.org/wiki/柴犬
+        let shiba_string = "「柴犬」という名前は中央高地で使われていたもので、文献上では、昭和初期の日本犬保存会の会誌「日本犬」で用いられている。一般的には、「柴」は小ぶりな雑木を指す。
+由来には諸説があり、
+
+    柴藪を巧みにくぐり抜けて猟を助けることから
+    赤褐色の毛色が枯れ柴に似ている（柴赤）ことから
+    小さなものを表す古語の「柴」から
+
+の3つの説が代表的。";
+        let shiba_bytes: Vec<u8> = shiba_string.bytes().collect();
+        f.write_all(&shiba_bytes[..]).unwrap();
+    }
+
+    std::fs::rename(&file_to_create, &file_to_rename_to).unwrap();
+    let mut file = fs::File::open(&file_to_rename_to).expect("Could not open file");
+    if file_to_create.exists() {
+        println!("The original file still exists!");
+        return;
+    } else {
+        println!("The original file does not still exist!");
+    }
+
+    let mut out_str = String::new();
+    file.read_to_string(&mut out_str).unwrap();
+    let mut test_str = String::new();
+    let mut out_chars = out_str.chars();
+    out_chars.next().unwrap();
+    test_str.push(out_chars.next().unwrap());
+    test_str.push(out_chars.next().unwrap());
+
+    println!("{}", test_str);
+    std::fs::remove_file(file_to_rename_to).unwrap();
+}

lib/wasi/src/macros.rs

@@ -17,3 +17,9 @@ macro_rules! wasi_try {
         wasi_try!(opt.ok_or($e))
     }};
 }
+
+macro_rules! get_input_str {
+    ($memory:expr, $data:expr, $len:expr) => {{
+        wasi_try!($data.get_utf8_string($memory, $len), __WASI_EINVAL)
+    }};
+}

lib/wasi/src/state/mod.rs

@@ -106,7 +106,7 @@ pub enum Kind {
     },
 }
 
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct Fd {
     pub rights: __wasi_rights_t,
     pub rights_inheriting: __wasi_rights_t,
@@ -126,6 +126,8 @@ pub struct WasiFs {
     pub fd_map: HashMap<u32, Fd>,
     pub next_fd: Cell<u32>,
     inode_counter: Cell<u64>,
+    /// for fds still open after the file has been deleted
+    pub orphan_fds: HashMap<Inode, InodeVal>,
 
     pub stdout: Box<dyn WasiFile>,
     pub stderr: Box<dyn WasiFile>,
@@ -146,6 +148,7 @@ impl WasiFs {
             fd_map: HashMap::new(),
             next_fd: Cell::new(3),
             inode_counter: Cell::new(1024),
+            orphan_fds: HashMap::new(),
 
             stdin: Box::new(Stdin(io::stdin())),
             stdout: Box::new(Stdout(io::stdout())),
@@ -683,6 +686,16 @@ impl WasiFs {
         self.fd_map.get(&fd).ok_or(__WASI_EBADF)
     }
 
+    /// gets either a normal inode or an orphaned inode
+    pub fn get_inodeval_mut(&mut self, fd: __wasi_fd_t) -> Result<&mut InodeVal, __wasi_errno_t> {
+        let inode = self.get_fd(fd)?.inode;
+        if let Some(iv) = self.inodes.get_mut(inode) {
+            Ok(iv)
+        } else {
+            self.orphan_fds.get_mut(&inode).ok_or(__WASI_EBADF)
+        }
+    }
+
     pub fn filestat_fd(&self, fd: __wasi_fd_t) -> Result<__wasi_filestat_t, __wasi_errno_t> {
         let fd = self.get_fd(fd)?;
 
@@ -818,8 +831,8 @@ impl WasiFs {
     /// all refences to the given inode have been removed from the filesystem
     ///
     /// returns true if the inode existed and was removed
-    pub unsafe fn remove_inode(&mut self, inode: Inode) -> bool {
-        self.inodes.remove(inode).is_some()
+    pub unsafe fn remove_inode(&mut self, inode: Inode) -> Option<InodeVal> {
+        self.inodes.remove(inode)
     }
 
     fn create_virtual_root(&mut self) -> Inode {

lib/wasi/src/state/types.rs

@@ -158,6 +158,13 @@ pub trait WasiFile: std::fmt::Debug + Write + Read + Seek {
     fn sync_to_disk(&self) -> Result<(), WasiFsError> {
         panic!("Default implementation for compatibilty in the 0.6.X releases; this will be removed in 0.7.0.  Please implement WasiFile::sync_to_disk for your type before then");
     }
+
+    /// Moves the file to a new location
+    /// NOTE: the signature of this function will change before stabilization
+    // TODO: stablizie this in 0.7.0 or 0.8.0 by removing default impl
+    fn rename_file(&self, _new_name: &std::path::Path) -> Result<(), WasiFsError> {
+        panic!("Default implementation for compatibilty in the 0.6.X releases; this will be removed in 0.7.0 or 0.8.0.  Please implement WasiFile::rename_file for your type before then");
+    }
 }
 
 pub trait WasiPath {}
@@ -271,6 +278,10 @@ impl WasiFile for HostFile {
     fn sync_to_disk(&self) -> Result<(), WasiFsError> {
         self.inner.sync_all().map_err(Into::into)
     }
+
+    fn rename_file(&self, new_name: &std::path::Path) -> Result<(), WasiFsError> {
+        std::fs::rename(&self.host_path, new_name).map_err(Into::into)
+    }
 }
 
 impl From<io::Error> for WasiFsError {