add a test of symlink happy path to isolate the windows failure

crates/test-programs/wasi-tests/src/bin/symlink_create.rs

@@ -0,0 +1,93 @@
+use libc;
+use more_asserts::assert_gt;
+use std::{env, process};
+use wasi_tests::open_scratch_directory;
+
+unsafe fn create_symlink_to_file(dir_fd: wasi::Fd) {
+    // Create a directory for the symlink to point to.
+    let target_fd =
+        wasi::path_open(dir_fd, 0, "target", wasi::OFLAGS_CREAT, 0, 0, 0).expect("creating a file");
+    wasi::fd_close(target_fd).expect("closing file");
+
+    // Create a symlink.
+    wasi::path_symlink("target", dir_fd, "symlink").expect("creating a symlink");
+
+    // Try to open it as a directory without O_NOFOLLOW.
+    let target_file_via_symlink = wasi::path_open(
+        dir_fd,
+        wasi::LOOKUPFLAGS_SYMLINK_FOLLOW,
+        "symlink",
+        0,
+        0,
+        0,
+        0,
+    )
+    .expect("opening a symlink as a directory");
+    assert_gt!(
+        target_file_via_symlink,
+        libc::STDERR_FILENO as wasi::Fd,
+        "file descriptor range check",
+    );
+    wasi::fd_close(target_file_via_symlink).expect("close the symlink file");
+
+    // Replace the target directory with a file.
+    wasi::path_unlink_file(dir_fd, "symlink").expect("removing the symlink");
+    wasi::path_unlink_file(dir_fd, "target").expect("removing the target file");
+}
+
+unsafe fn create_symlink_to_directory(dir_fd: wasi::Fd) {
+    // Create a directory for the symlink to point to.
+    wasi::path_create_directory(dir_fd, "target").expect("creating a dir");
+
+    // Create a symlink.
+    wasi::path_symlink("target", dir_fd, "symlink").expect("creating a symlink");
+
+    // Try to open it as a directory without O_NOFOLLOW.
+    let target_dir_via_symlink = wasi::path_open(
+        dir_fd,
+        wasi::LOOKUPFLAGS_SYMLINK_FOLLOW,
+        "symlink",
+        wasi::OFLAGS_DIRECTORY,
+        0,
+        0,
+        0,
+    )
+    .expect("opening a symlink as a directory");
+    assert_gt!(
+        target_dir_via_symlink,
+        libc::STDERR_FILENO as wasi::Fd,
+        "file descriptor range check",
+    );
+    wasi::fd_close(target_dir_via_symlink).expect("closing a file");
+
+    // Replace the target directory with a file.
+    wasi::path_unlink_file(dir_fd, "symlink").expect("removing a file");
+    wasi::path_remove_directory(dir_fd, "target")
+        .expect("remove_directory on a directory should succeed");
+}
+
+fn main() {
+    let mut args = env::args();
+    let prog = args.next().unwrap();
+    let arg = if let Some(arg) = args.next() {
+        arg
+    } else {
+        eprintln!("usage: {} <scratch directory>", prog);
+        process::exit(1);
+    };
+
+    // Open scratch directory
+    let dir_fd = match open_scratch_directory(&arg) {
+        Ok(dir_fd) => dir_fd,
+        Err(err) => {
+            eprintln!("{}", err);
+            process::exit(1)
+        }
+    };
+
+    // Run the tests.
+    unsafe {
+        create_symlink_to_file(dir_fd);
+        create_symlink_to_directory(dir_fd);
+    }
+}