cp: support symlinks on WASI

.github/workflows/wasi.yml

@@ -60,7 +60,7 @@ jobs:
         # Tests incompatible with WASI are annotated with
         # #[cfg_attr(wasi_runner, ignore)] in the test source files.
         # TODO: add integration tests for these tools as WASI support is extended:
-        #   arch b2sum cat cksum cp csplit date dir dircolors fmt join
+        #   arch b2sum cat cksum csplit date dir dircolors fmt join
         #   ls md5sum mkdir mv nproc pathchk pr printenv ptx pwd readlink
         #   realpath rm rmdir seq sha1sum sha224sum sha256sum sha384sum
         #   sha512sum shred sleep sort split tail touch tsort uname uniq
@@ -69,6 +69,7 @@ jobs:
         UUTESTS_WASM_RUNNER=wasmtime \
         cargo test --test tests -- \
           test_base32:: test_base64:: test_basenc:: test_basename:: \
+          test_cp::test_cp_arg_symlink \
           test_comm:: test_cut:: test_dirname:: test_echo:: \
           test_expand:: test_factor:: test_false:: test_fold:: \
           test_head:: test_link:: test_ln:: test_nl:: test_numfmt:: \

src/uu/cp/Cargo.toml

@@ -49,6 +49,9 @@ windows-sys = { workspace = true, features = [
   "Win32_Storage_FileSystem",
 ] }
 
+[target.'cfg(target_os = "wasi")'.dependencies]
+rustix = { workspace = true, features = ["fs"] }
+
 [[bin]]
 name = "cp"
 path = "src/main.rs"

src/uu/cp/src/cp.rs

@@ -1959,18 +1959,8 @@ pub(crate) fn copy_attributes(
 fn symlink_file(
     source: &Path,
     dest: &Path,
-    #[cfg(not(target_os = "wasi"))] symlinked_files: &mut HashSet<FileInformation>,
-    #[cfg(target_os = "wasi")] _symlinked_files: &mut HashSet<FileInformation>,
+    symlinked_files: &mut HashSet<FileInformation>,
 ) -> CopyResult<()> {
-    #[cfg(target_os = "wasi")]
-    {
-        Err(CpError::IoErrContext(
-            io::Error::new(io::ErrorKind::Unsupported, "symlinks not supported"),
-            translate!("cp-error-cannot-create-symlink",
-                       "dest" => get_filename(dest).unwrap_or("?").quote(),
-                       "source" => get_filename(source).unwrap_or("?").quote()),
-        ))
-    }
     #[cfg(not(any(windows, target_os = "wasi")))]
     {
         std::os::unix::fs::symlink(source, dest).map_err(|e| {
@@ -1993,13 +1983,21 @@ fn symlink_file(
             )
         })?;
     }
-    #[cfg(not(target_os = "wasi"))]
+    #[cfg(target_os = "wasi")]
     {
-        if let Ok(file_info) = FileInformation::from_path(dest, false) {
-            symlinked_files.insert(file_info);
-        }
-        Ok(())
+        platform::create_symlink(source, dest).map_err(|e| {
+            CpError::IoErrContext(
+                e,
+                translate!("cp-error-cannot-create-symlink",
+                           "dest" => get_filename(dest).unwrap_or("?").quote(),
+                           "source" => get_filename(source).unwrap_or("?").quote()),
+            )
+        })?;
     }
+    if let Ok(file_info) = FileInformation::from_path(dest, false) {
+        symlinked_files.insert(file_info);
+    }
+    Ok(())
 }
 
 fn context_for(src: &Path, dest: &Path) -> String {

src/uu/cp/src/platform/mod.rs

@@ -33,3 +33,8 @@ pub(crate) use self::windows::copy_on_write;
 mod other;
 #[cfg(not(any(unix, target_os = "windows")))]
 pub(crate) use self::other::copy_on_write;
+
+#[cfg(target_os = "wasi")]
+mod wasi;
+#[cfg(target_os = "wasi")]
+pub(crate) use self::wasi::create_symlink;

src/uu/cp/src/platform/wasi.rs

@@ -0,0 +1,11 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use std::io;
+use std::path::Path;
+
+pub(crate) fn create_symlink(source: &Path, dest: &Path) -> io::Result<()> {
+    rustix::fs::symlink(source, dest).map_err(io::Error::from)
+}

tests/by-util/test_cp.rs

@@ -28,7 +28,6 @@ use std::os::unix::fs::PermissionsExt;
 use std::os::unix::fs::{FileTypeExt, MetadataExt};
 #[cfg(windows)]
 use std::os::windows::fs::symlink_file;
-#[cfg(not(windows))]
 use std::path::Path;
 #[cfg(target_os = "linux")]
 use std::path::PathBuf;
@@ -924,6 +923,11 @@ fn test_cp_arg_symlink() {
         .succeeds();
 
     assert!(at.is_symlink(TEST_HELLO_WORLD_DEST));
+    assert_eq!(
+        std::fs::read_link(at.plus(TEST_HELLO_WORLD_DEST)).unwrap(),
+        Path::new(TEST_HELLO_WORLD_SOURCE)
+    );
+    assert_eq!(at.read(TEST_HELLO_WORLD_DEST), "Hello, World!\n");
 }
 
 // Recursively copying a tree that contains a symlink must not run chmod through