vexos: dedupe fs create/create_new status logic

Author: tropicaaal

library/std/src/sys/fs/vexos.rs

@@ -222,6 +222,24 @@ impl OpenOptions {
 impl File {
     pub fn open(path: &Path, opts: &OpenOptions) -> io::Result<File> {
         run_path_with_cstr(path, &|path| {
+            // Enforce the invariants of `create_new`/`create`.
+            //
+            // Since VEXos doesn't have anything akin to POSIX's `oflags`, we need to enforce
+            // the requirements that `create_new` can't have an existing file and `!create`
+            // doesn't create a file ourselves.
+            if !opts.read && (opts.write || opts.append) && (opts.create_new || !opts.create) {
+                let status = vex_sdk::vexFileStatus(path.as_ptr());
+
+                if opts.create_new && status != 0 {
+                    return Err(io::const_error!(io::ErrorKind::AlreadyExists, "File exists",));
+                } else if !opts.create && status == 0 {
+                    return Err(io::const_error!(
+                        io::ErrorKind::NotFound,
+                        "No such file or directory",
+                    ));
+                }
+            }
+
             let file = match opts {
                 // read + write - unsupported
                 OpenOptions { read: true, write: true, .. } => {
@@ -247,53 +265,19 @@ impl File {
                     write: _,
                     append: true,
                     truncate: false,
-                    create,
-                    create_new,
-                } => unsafe {
-                    if *create_new {
-                        if vex_sdk::vexFileStatus(path.as_ptr()) != 0 {
-                            return Err(io::const_error!(
-                                io::ErrorKind::AlreadyExists,
-                                "File exists",
-                            ));
-                        }
-                    } else if !*create {
-                        if vex_sdk::vexFileStatus(path.as_ptr()) == 0 {
-                            return Err(io::const_error!(
-                                io::ErrorKind::NotFound,
-                                "No such file or directory",
-                            ));
-                        }
-                    }
-
-                    vex_sdk::vexFileOpenWrite(path.as_ptr())
-                },
+                    create: _,
+                    create_new: _,
+                } => unsafe { vex_sdk::vexFileOpenWrite(path.as_ptr()) },
 
                 // write
                 OpenOptions {
                     read: false,
                     write: true,
                     append: false,
                     truncate,
-                    create,
-                    create_new,
+                    create: _,
+                    create_new: _,
                 } => unsafe {
-                    if *create_new {
-                        if vex_sdk::vexFileStatus(path.as_ptr()) != 0 {
-                            return Err(io::const_error!(
-                                io::ErrorKind::AlreadyExists,
-                                "File exists",
-                            ));
-                        }
-                    } else if !*create {
-                        if vex_sdk::vexFileStatus(path.as_ptr()) == 0 {
-                            return Err(io::const_error!(
-                                io::ErrorKind::NotFound,
-                                "No such file or directory",
-                            ));
-                        }
-                    }
-
                     if *truncate {
                         vex_sdk::vexFileOpenCreate(path.as_ptr())
                     } else {