Reenable cap-async-std. (#370)

* Reenable cap-async-std.

async-std 1.13.0 is now released with the "io_safety" feature, which
means we can now reenable cap-async-std.

* Update to io-extras 0.18.3.

Author: sunfishcode

Cargo.toml

@@ -17,15 +17,15 @@ exclude = ["/.*"]
 rust-version = "1.63"
 
 [dev-dependencies]
-#async-std = { version = "1.10.0", features = ["attributes"] }
+async-std = { version = "1.13.0", features = ["attributes", "io_safety"] }
 anyhow = "1.0.37"
-#cap-async-std = { path = "cap-async-std", version = "^0.25.0" }
-cap-fs-ext = { path = "cap-fs-ext", version = "^3.3.0" }
-cap-net-ext = { path = "cap-net-ext", version = "^3.3.0" }
-cap-directories = { path = "cap-directories", version = "^3.3.0" }
-cap-std = { path = "cap-std", version = "^3.3.0" }
-cap-tempfile = { path = "cap-tempfile", version = "^3.3.0" }
-cap-rand = { path = "cap-rand", version = "^3.3.0" }
+cap-async-std = { path = "cap-async-std", version = "3.3.0" }
+cap-fs-ext = { path = "cap-fs-ext", version = "3.3.0" }
+cap-net-ext = { path = "cap-net-ext", version = "3.3.0" }
+cap-directories = { path = "cap-directories", version = "3.3.0" }
+cap-std = { path = "cap-std", version = "3.3.0" }
+cap-tempfile = { path = "cap-tempfile", version = "3.3.0" }
+cap-rand = { path = "cap-rand", version = "3.3.0" }
 rand = "0.8.1"
 tempfile = "3.1.0"
 camino = "1.0.5"
@@ -55,23 +55,23 @@ fs_utf8 = [
     "cap-fs-ext/fs_utf8",
     "cap-tempfile/fs_utf8",
 ]
-#async_std_fs_utf8 = [
-#    "cap-async-std/fs_utf8",
-#    "cap-fs-ext/async_std_fs_utf8"
-#]
+async_std_fs_utf8 = [
+    "cap-async-std/fs_utf8",
+    "cap-fs-ext/async_std_fs_utf8"
+]
 arf_strings = [
     "cap-std/arf_strings",
     "cap-fs-ext/arf_strings",
     "cap-tempfile/arf_strings",
 ]
-#async_std_arf_strings = [
-#    "cap-async-std/arf_strings",
-#    "cap-fs-ext/async_std_arf_strings"
-#]
+async_std_arf_strings = [
+    "cap-async-std/arf_strings",
+    "cap-fs-ext/async_std_arf_strings"
+]
 
 [workspace]
 members = [
-  #"cap-async-std",
+  "cap-async-std",
   "cap-fs-ext",
   "cap-net-ext",
   "cap-directories",

cap-async-std/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cap-async-std"
-version = "0.25.2"
+version = "3.3.0"
 description = "Capability-based version of async-std"
 authors = [
     "Dan Gohman <[email protected]>",
@@ -11,15 +11,13 @@ keywords = ["network", "file", "async", "future", "await"]
 categories = ["filesystem", "network-programming", "asynchronous", "concurrency"]
 repository = "https://github.com/bytecodealliance/cap-std"
 edition = "2021"
-publish = false # temporary, until async-rs/async-std#1036 is available
 
 [dependencies]
 arf-strings = { version = "0.7.0", optional = true }
-# Enable "unstable" for `spawn_blocking`.
-async-std = { version = "1.10.0", features = ["attributes", "unstable"] }
-cap-primitives = { path = "../cap-primitives", version = "^0.25.0" }
+async-std = { version = "1.13.0", features = ["attributes", "io_safety"] }
+cap-primitives = { path = "../cap-primitives", version = "^3.3.0" }
 io-lifetimes = { version = "2.0.0", default-features = false, features = ["async-std"] }
-io-extras = { version = "0.17.0", features = ["use_async_std"] }
+io-extras = { version = "0.18.3", features = ["use_async_std"] }
 camino = { version = "1.0.5", optional = true }
 
 [target.'cfg(not(windows))'.dependencies]

cap-async-std/build.rs

@@ -0,0 +1,84 @@
+use std::env::var;
+use std::io::Write;
+
+fn main() {
+    use_feature_or_nothing("windows_file_type_ext");
+
+    // Cfgs that users may set.
+    println!("cargo:rustc-check-cfg=cfg(io_lifetimes_use_std)");
+
+    // Don't rerun this on changes other than build.rs, as we only depend on
+    // the rustc version.
+    println!("cargo:rerun-if-changed=build.rs");
+}
+
+fn use_feature_or_nothing(feature: &str) {
+    if has_feature(feature) {
+        use_feature(feature);
+    }
+    println!("cargo:rustc-check-cfg=cfg({})", feature);
+}
+
+fn use_feature(feature: &str) {
+    println!("cargo:rustc-cfg={}", feature);
+}
+
+/// Test whether the rustc at `var("RUSTC")` supports the given feature.
+fn has_feature(feature: &str) -> bool {
+    can_compile(&format!(
+        "#![allow(stable_features)]\n#![feature({})]",
+        feature
+    ))
+}
+
+/// Test whether the rustc at `var("RUSTC")` can compile the given code.
+fn can_compile<T: AsRef<str>>(test: T) -> bool {
+    use std::process::Stdio;
+
+    let out_dir = var("OUT_DIR").unwrap();
+    let rustc = var("RUSTC").unwrap();
+    let target = var("TARGET").unwrap();
+
+    // Use `RUSTC_WRAPPER` if it's set, unless it's set to an empty string,
+    // as documented [here].
+    // [here]: https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-reads
+    let wrapper = var("RUSTC_WRAPPER")
+        .ok()
+        .and_then(|w| if w.is_empty() { None } else { Some(w) });
+
+    let mut cmd = if let Some(wrapper) = wrapper {
+        let mut cmd = std::process::Command::new(wrapper);
+        // The wrapper's first argument is supposed to be the path to rustc.
+        cmd.arg(rustc);
+        cmd
+    } else {
+        std::process::Command::new(rustc)
+    };
+
+    cmd.arg("--crate-type=rlib") // Don't require `main`.
+        .arg("--emit=metadata") // Do as little as possible but still parse.
+        .arg("--target")
+        .arg(target)
+        .arg("--out-dir")
+        .arg(out_dir); // Put the output somewhere inconsequential.
+
+    // If Cargo wants to set RUSTFLAGS, use that.
+    if let Ok(rustflags) = var("CARGO_ENCODED_RUSTFLAGS") {
+        if !rustflags.is_empty() {
+            for arg in rustflags.split('\x1f') {
+                cmd.arg(arg);
+            }
+        }
+    }
+
+    let mut child = cmd
+        .arg("-") // Read from stdin.
+        .stdin(Stdio::piped()) // Stdin is a pipe.
+        .stderr(Stdio::null()) // Errors from feature detection aren't interesting and can be confusing.
+        .spawn()
+        .unwrap();
+
+    writeln!(child.stdin.take().unwrap(), "{}", test.as_ref()).unwrap();
+
+    child.wait().unwrap().success()
+}

cap-async-std/src/fs/dir.rs

@@ -13,12 +13,14 @@ use cap_primitives::fs::{
     remove_open_dir_all, rename, set_permissions, stat, DirOptions, FollowSymlinks, Permissions,
 };
 use cap_primitives::AmbientAuthority;
+use io_lifetimes::raw::{AsRawFilelike, FromRawFilelike};
 #[cfg(not(windows))]
 use io_lifetimes::{AsFd, BorrowedFd, OwnedFd};
 use io_lifetimes::{AsFilelike, FromFilelike};
 #[cfg(windows)]
 use io_lifetimes::{AsHandle, BorrowedHandle, OwnedHandle};
 use std::fmt;
+use std::mem::ManuallyDrop;
 #[cfg(unix)]
 use {
     crate::os::unix::net::{UnixDatagram, UnixListener, UnixStream},
@@ -883,15 +885,20 @@ impl Dir {
     /// This can be useful when interacting with other libraries and or C/C++
     /// code which has invoked `openat(..., O_DIRECTORY)` external to this
     /// crate.
-    pub fn reopen_dir<Filelike: AsFilelike>(dir: &Filelike) -> io::Result<Self> {
-        spawn_blocking(move || {
-            cap_primitives::fs::open_dir(
-                &dir.as_filelike_view::<std::fs::File>(),
-                std::path::Component::CurDir.as_ref(),
-            )
+    pub async fn reopen_dir<Filelike: AsFilelike + Send>(dir: &Filelike) -> io::Result<Self> {
+        // Our public API has a `&Filelike` here, which prevents us from doing
+        // a `clone` as we usually do. So instead, we use the raw filelike, which
+        // we can clone and depend on it remaining open until we return.
+        let raw_filelike = dir.as_filelike_view::<std::fs::File>().as_raw_filelike();
+        // SAFETY: `raw_filelike` remains open for the duration of the
+        // `reopen_dir` call.
+        let file = ManuallyDrop::new(unsafe { std::fs::File::from_raw_filelike(raw_filelike) });
+        let dir = spawn_blocking(move || {
+            cap_primitives::fs::open_dir(&*file, std::path::Component::CurDir.as_ref())
         })
-        .await
-        .map(Self::from_std_file)
+        .await?
+        .into();
+        Ok(Self::from_std_file(dir))
     }
 }
 

cap-async-std/src/fs/file.rs

@@ -90,8 +90,7 @@ impl File {
     #[inline]
     pub async fn metadata(&self) -> io::Result<Metadata> {
         let clone = self.clone();
-        let sync = clone.std.as_filelike_view::<std::fs::File>();
-        spawn_blocking(move || metadata_from(&*sync)).await
+        spawn_blocking(move || metadata_from(&*clone.std.as_filelike_view::<std::fs::File>())).await
     }
 
     // async_std doesn't have `try_clone`.

cap-async-std/src/fs/mod.rs

@@ -40,9 +40,9 @@ pub use cap_primitives::fs::{DirBuilder, FileType, Metadata, OpenOptions, Permis
 // Re-export conditional types from `cap_primitives`.
 #[cfg(any(unix, target_os = "vxworks", all(windows, windows_file_type_ext)))]
 pub use cap_primitives::fs::FileTypeExt;
-pub use cap_primitives::fs::{FileExt, OpenOptionsExt, MetadataExt};
 #[cfg(unix)]
 pub use cap_primitives::fs::{DirBuilderExt, PermissionsExt};
+pub use cap_primitives::fs::{FileExt, MetadataExt, OpenOptionsExt};
 
 // Re-export things from `async_std` that we can use as-is.
 #[cfg(target_os = "wasi")]

cap-async-std/src/fs_utf8/dir.rs

@@ -3,12 +3,14 @@ use crate::fs_utf8::{from_utf8, to_utf8, DirBuilder, File, Metadata, ReadDir};
 use async_std::{fs, io};
 use camino::{Utf8Path, Utf8PathBuf};
 use cap_primitives::AmbientAuthority;
+use io_lifetimes::raw::{AsRawFilelike, FromRawFilelike};
 use io_lifetimes::AsFilelike;
 #[cfg(not(windows))]
-use io_lifetimes::{AsFd, BorrowedFd, FromFd, IntoFd, OwnedFd};
+use io_lifetimes::{AsFd, BorrowedFd, OwnedFd};
 #[cfg(windows)]
 use io_lifetimes::{AsHandle, BorrowedHandle, OwnedHandle};
 use std::fmt;
+use std::mem::ManuallyDrop;
 #[cfg(unix)]
 use {
     crate::os::unix::net::{UnixDatagram, UnixListener, UnixStream},
@@ -170,8 +172,8 @@ impl Dir {
         to_dir: &Self,
         to: Q,
     ) -> io::Result<u64> {
-        let from = from_utf8(from)?;
-        let to = from_utf8(to)?;
+        let from = from_utf8(from.as_ref())?;
+        let to = from_utf8(to.as_ref())?;
         self.cap_std.copy(from, &to_dir.cap_std, to).await
     }
 
@@ -186,8 +188,8 @@ impl Dir {
         dst_dir: &Self,
         dst: Q,
     ) -> io::Result<()> {
-        let src = from_utf8(src)?;
-        let dst = from_utf8(dst)?;
+        let src = from_utf8(src.as_ref())?;
+        let dst = from_utf8(dst.as_ref())?;
         self.cap_std.hard_link(src, &dst_dir.cap_std, dst).await
     }
 
@@ -321,8 +323,8 @@ impl Dir {
         to_dir: &Self,
         to: Q,
     ) -> io::Result<()> {
-        let from = from_utf8(from)?;
-        let to = from_utf8(to)?;
+        let from = from_utf8(from.as_ref())?;
+        let to = from_utf8(to.as_ref())?;
         self.cap_std.rename(from, &to_dir.cap_std, to).await
     }
 
@@ -388,8 +390,8 @@ impl Dir {
         original: P,
         link: Q,
     ) -> io::Result<()> {
-        let original = from_utf8(original)?;
-        let link = from_utf8(link)?;
+        let original = from_utf8(original.as_ref())?;
+        let link = from_utf8(link.as_ref())?;
         self.cap_std.symlink(original, link).await
     }
 
@@ -416,8 +418,8 @@ impl Dir {
         original: P,
         link: Q,
     ) -> io::Result<()> {
-        let original = from_utf8(original)?;
-        let link = from_utf8(link)?;
+        let original = from_utf8(original.as_ref())?;
+        let link = from_utf8(link.as_ref())?;
         self.cap_std.symlink_file(original, link).await
     }
 
@@ -444,8 +446,8 @@ impl Dir {
         original: P,
         link: Q,
     ) -> io::Result<()> {
-        let original = from_utf8(original)?;
-        let link = from_utf8(link)?;
+        let original = from_utf8(original.as_ref())?;
+        let link = from_utf8(link.as_ref())?;
         self.cap_std.symlink_dir(original, link).await
     }
 
@@ -655,15 +657,17 @@ impl Dir {
     /// This can be useful when interacting with other libraries and or C/C++
     /// code which has invoked `openat(..., O_DIRECTORY)` external to this
     /// crate.
-    pub fn reopen_dir<Filelike: AsFilelike>(dir: &Filelike) -> io::Result<Self> {
-        spawn_blocking(move || {
-            cap_primitives::fs::open_dir(
-                &dir.as_filelike_view::<std::fs::File>(),
-                std::path::Component::CurDir.as_ref(),
-            )
-        })
-        .await
-        .map(Self::from_std_file)
+    pub async fn reopen_dir<Filelike: AsFilelike>(dir: &Filelike) -> io::Result<Self> {
+        // Our public API has a `&Filelike` here, which prevents us from doing
+        // a `clone` as we usually do. So instead, we use the raw fd, which we
+        // can clone and depend on it remaining open until we return.
+        let raw_filelike = dir.as_filelike_view::<std::fs::File>().as_raw_filelike();
+        // SAFETY: `raw_filelike` remains open for the duration of the `reopen_dir`
+        // call.
+        let file = ManuallyDrop::new(unsafe { std::fs::File::from_raw_filelike(raw_filelike) });
+        crate::fs::Dir::reopen_dir(&*file)
+            .await
+            .map(Self::from_cap_std)
     }
 }
 

cap-async-std/src/fs_utf8/file.rs

@@ -10,7 +10,7 @@ use async_std::task::{Context, Poll};
 use camino::Utf8Path;
 use cap_primitives::AmbientAuthority;
 #[cfg(not(windows))]
-use io_lifetimes::{AsFd, BorrowedFd, FromFd, IntoFd, OwnedFd};
+use io_lifetimes::{AsFd, BorrowedFd, OwnedFd};
 #[cfg(windows)]
 use io_lifetimes::{AsHandle, BorrowedHandle, OwnedHandle};
 use std::fmt;
@@ -93,8 +93,7 @@ impl File {
     /// This corresponds to [`async_std::fs::File::metadata`].
     #[inline]
     pub async fn metadata(&self) -> io::Result<Metadata> {
-        let clone = self.clone();
-        spawn_blocking(move || clone.metadata()).await
+        self.cap_std.metadata().await
     }
 
     // async_std doesn't have `try_clone`.
@@ -119,7 +118,7 @@ impl File {
         path: P,
         ambient_authority: AmbientAuthority,
     ) -> io::Result<Self> {
-        let path = from_utf8(path)?;
+        let path = from_utf8(path.as_ref())?;
         crate::fs::File::open_ambient(path, ambient_authority)
             .await
             .map(Self::from_cap_std)
@@ -134,11 +133,11 @@ impl File {
     /// This function is not sandboxed and may access any path that the host
     /// process has access to.
     #[inline]
-    pub async fn create_ambient<P: AsRef<Path>>(
+    pub async fn create_ambient<P: AsRef<Utf8Path>>(
         path: P,
         ambient_authority: AmbientAuthority,
     ) -> io::Result<Self> {
-        let path = from_utf8(path)?;
+        let path = from_utf8(path.as_ref())?;
         crate::fs::File::create_ambient(path, ambient_authority)
             .await
             .map(Self::from_cap_std)
@@ -158,7 +157,7 @@ impl File {
         options: &OpenOptions,
         ambient_authority: AmbientAuthority,
     ) -> io::Result<Self> {
-        let path = from_utf8(path)?;
+        let path = from_utf8(path.as_ref())?;
         crate::fs::File::open_ambient_with(path, options, ambient_authority)
             .await
             .map(Self::from_cap_std)