Test path_open O_EXCL behaviour

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

@@ -0,0 +1,65 @@
+use std::{env, process};
+use wasi::wasi_unstable;
+use wasi_tests::open_scratch_directory;
+use wasi_tests::utils::{cleanup_file, close_fd};
+use wasi_tests::wasi_wrappers::wasi_path_open;
+
+unsafe fn test_path_open_create_existing(dir_fd: wasi_unstable::Fd) {
+    let mut fd: wasi_unstable::Fd = wasi_unstable::Fd::max_value() - 1;
+    let mut status = wasi_path_open(
+        dir_fd,
+        0,
+        "file",
+        wasi_unstable::O_CREAT | wasi_unstable::O_EXCL,
+        0,
+        0,
+        0,
+        &mut fd,
+    );
+    assert_eq!(
+        status,
+        wasi_unstable::raw::__WASI_ESUCCESS,
+        "creating a file"
+    );
+    close_fd(fd);
+    fd = wasi_unstable::Fd::max_value() - 1;
+    status = wasi_path_open(
+        dir_fd,
+        0,
+        "file",
+        wasi_unstable::O_CREAT | wasi_unstable::O_EXCL,
+        0,
+        0,
+        0,
+        &mut fd,
+    );
+    assert_eq!(
+        status,
+        wasi_unstable::raw::__WASI_EEXIST,
+        "trying to create a file that already exists"
+    );
+    cleanup_file(dir_fd, "file");
+}
+
+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 { test_path_open_create_existing(dir_fd) }
+}