simplify life for readdir implementors

crates/wasi-common/cap-std-sync/src/dir.rs

@@ -1,7 +1,6 @@
 use crate::file::{filetype_from, File};
 use cap_fs_ext::{DirEntryExt, DirExt, MetadataExt, SystemTimeSpec};
 use std::any::Any;
-use std::convert::TryInto;
 use std::path::{Path, PathBuf};
 use system_interface::fs::GetSetFdFlags;
 use wasi_common::{
@@ -101,7 +100,7 @@ impl WasiDir for Dir {
     fn readdir(
         &self,
         cursor: ReaddirCursor,
-    ) -> Result<Box<dyn Iterator<Item = Result<(ReaddirEntity, String), Error>>>, Error> {
+    ) -> Result<Box<dyn Iterator<Item = Result<ReaddirEntity, Error>>>, Error> {
         // cap_std's read_dir does not include . and .., we should prepend these.
         // Why does the Ok contain a tuple? We can't construct a cap_std::fs::DirEntry, and we don't
         // have enough info to make a ReaddirEntity yet.
@@ -109,13 +108,11 @@ impl WasiDir for Dir {
         let rd = vec![
             {
                 let name = ".".to_owned();
-                let namelen = name.as_bytes().len().try_into().expect("1 wont overflow");
-                Ok((FileType::Directory, dir_meta.ino(), namelen, name))
+                Ok((FileType::Directory, dir_meta.ino(), name))
             },
             {
                 let name = "..".to_owned();
-                let namelen = name.as_bytes().len().try_into().expect("2 wont overflow");
-                Ok((FileType::Directory, dir_meta.ino(), namelen, name))
+                Ok((FileType::Directory, dir_meta.ino(), name))
             },
         ]
         .into_iter()
@@ -130,22 +127,18 @@ impl WasiDir for Dir {
                     .file_name()
                     .into_string()
                     .map_err(|_| Error::illegal_byte_sequence().context("filename"))?;
-                let namelen = name.as_bytes().len().try_into()?;
-                Ok((filetype, inode, namelen, name))
+                Ok((filetype, inode, name))
             }),
         )
         // Enumeration of the iterator makes it possible to define the ReaddirCursor
         .enumerate()
         .map(|(ix, r)| match r {
-            Ok((filetype, inode, namelen, name)) => Ok((
-                ReaddirEntity {
-                    next: ReaddirCursor::from(ix as u64 + 1),
-                    filetype,
-                    inode,
-                    namelen,
-                },
+            Ok((filetype, inode, name)) => Ok(ReaddirEntity {
+                next: ReaddirCursor::from(ix as u64 + 1),
+                filetype,
+                inode,
                 name,
-            )),
+            }),
             Err(e) => Err(e),
         })
         .skip(u64::from(cursor) as usize);
@@ -286,8 +279,8 @@ mod test {
                 .readdir(ReaddirCursor::from(0))
                 .expect("readdir succeeds")
             {
-                let (entity, name) = readdir_result.expect("readdir entry is valid");
-                out.insert(name, entity);
+                let entity = readdir_result.expect("readdir entry is valid");
+                out.insert(entity.name.clone(), entity);
             }
             out
         }

crates/wasi-common/src/dir.rs

@@ -22,7 +22,7 @@ pub trait WasiDir {
     fn readdir(
         &self,
         cursor: ReaddirCursor,
-    ) -> Result<Box<dyn Iterator<Item = Result<(ReaddirEntity, String), Error>>>, Error>;
+    ) -> Result<Box<dyn Iterator<Item = Result<ReaddirEntity, Error>>>, Error>;
     fn symlink(&self, old_path: &str, new_path: &str) -> Result<(), Error>;
     fn remove_dir(&self, path: &str) -> Result<(), Error>;
     fn unlink_file(&self, path: &str) -> Result<(), Error>;
@@ -166,7 +166,7 @@ impl TableDirExt for crate::table::Table {
 pub struct ReaddirEntity {
     pub next: ReaddirCursor,
     pub inode: u64,
-    pub namelen: u32,
+    pub name: String,
     pub filetype: FileType,
 }
 

crates/wasi-common/src/snapshots/preview_1.rs

@@ -640,16 +640,16 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
     ) -> Result<types::Size, Error> {
         let mut bufused = 0;
         let mut buf = buf.clone();
-        for pair in self
+        for entity in self
             .table()
             .get_dir(u32::from(fd))?
             .get_cap(DirCaps::READDIR)?
             .readdir(ReaddirCursor::from(cookie))?
         {
-            let (entity, name) = pair?;
-            let dirent_raw = dirent_bytes(types::Dirent::from(&entity));
+            let entity = entity?;
+            let dirent_raw = dirent_bytes(types::Dirent::try_from(&entity)?);
             let dirent_len: types::Size = dirent_raw.len().try_into()?;
-            let name_raw = name.as_bytes();
+            let name_raw = entity.name.as_bytes();
             let name_len: types::Size = name_raw.len().try_into()?;
 
             // Copy as many bytes of the dirent as we can, up to the end of the buffer
@@ -1438,14 +1438,15 @@ impl From<Filestat> for types::Filestat {
     }
 }
 
-impl From<&ReaddirEntity> for types::Dirent {
-    fn from(e: &ReaddirEntity) -> types::Dirent {
-        types::Dirent {
+impl TryFrom<&ReaddirEntity> for types::Dirent {
+    type Error = Error;
+    fn try_from(e: &ReaddirEntity) -> Result<types::Dirent, Error> {
+        Ok(types::Dirent {
             d_ino: e.inode,
-            d_namlen: e.namelen,
+            d_namlen: e.name.as_bytes().len().try_into()?,
             d_type: types::Filetype::from(&e.filetype),
             d_next: e.next.into(),
-        }
+        })
     }
 }