Dir::open_file can just pass read/write as bools, centralizing FileCaps decoding

this way the impls of File/Dir don't need to know about any caps!

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

@@ -5,7 +5,7 @@ use std::convert::TryInto;
 use std::path::{Path, PathBuf};
 use wasi_common::{
     dir::{ReaddirCursor, ReaddirEntity, WasiDir},
-    file::{FdFlags, FileCaps, FileType, Filestat, OFlags, WasiFile},
+    file::{FdFlags, FileType, Filestat, OFlags, WasiFile},
     Error, ErrorExt,
 };
 
@@ -26,7 +26,8 @@ impl WasiDir for Dir {
         symlink_follow: bool,
         path: &str,
         oflags: OFlags,
-        caps: FileCaps,
+        read: bool,
+        write: bool,
         fdflags: FdFlags,
     ) -> Result<Box<dyn WasiFile>, Error> {
         use cap_fs_ext::{FollowSymlinks, OpenOptionsFollowExt};
@@ -43,11 +44,10 @@ impl WasiDir for Dir {
         if oflags.contains(OFlags::TRUNCATE) {
             opts.truncate(true);
         }
-        if caps.contains(FileCaps::WRITE)
-            || caps.contains(FileCaps::DATASYNC)
-            || caps.contains(FileCaps::ALLOCATE)
-            || caps.contains(FileCaps::FILESTAT_SET_SIZE)
-        {
+        if read {
+            opts.read(true);
+        }
+        if write {
             opts.write(true);
         } else {
             // If not opened write, open read. This way the OS lets us open the file.
@@ -55,9 +55,6 @@ impl WasiDir for Dir {
             // get_cap check.
             opts.read(true);
         }
-        if caps.contains(FileCaps::READ) {
-            opts.read(true);
-        }
         if fdflags.contains(FdFlags::APPEND) {
             opts.append(true);
         }

crates/wasi-common/src/dir.rs

@@ -13,7 +13,8 @@ pub trait WasiDir {
         symlink_follow: bool,
         path: &str,
         oflags: OFlags,
-        caps: FileCaps,
+        read: bool,
+        write: bool,
         fdflags: FdFlags,
     ) -> Result<Box<dyn WasiFile>, Error>;
     fn open_dir(&self, symlink_follow: bool, path: &str) -> Result<Box<dyn WasiDir>, Error>;

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

@@ -813,7 +813,11 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
 
             let file_caps = dir_entry.child_file_caps(FileCaps::from(&fs_rights_base));
             let dir = dir_entry.get_cap(required_caps)?;
-            let file = dir.open_file(symlink_follow, path.deref(), oflags, file_caps, fdflags)?;
+            let read = file_caps.contains(FileCaps::READ);
+            let write = file_caps.contains(FileCaps::WRITE)
+                || file_caps.contains(FileCaps::ALLOCATE)
+                || file_caps.contains(FileCaps::FILESTAT_SET_SIZE);
+            let file = dir.open_file(symlink_follow, path.deref(), oflags, read, write, fdflags)?;
             drop(dir);
             let fd = table.push(Box::new(FileEntry::new(file_caps, file)))?;
             Ok(types::Fd::from(fd))