requested changes

Author: Qelxiros

library/std/src/fs.rs

@@ -153,7 +153,6 @@ pub enum TryLockError {
     WouldBlock,
 }
 
-#[unstable(feature = "dirfd", issue = "120426")]
 /// An object providing access to a directory on the filesystem.
 ///
 /// Files are automatically closed when they go out of scope.  Errors detected
@@ -165,14 +164,18 @@ pub enum TryLockError {
 ///
 /// ```no_run
 /// #![feature(dirfd)]
-/// use std::fs::Dir;
+/// use std::{fs::Dir, io::Read};
 ///
 /// fn main() -> std::io::Result<()> {
 ///     let dir = Dir::new("foo")?;
-///     let file = dir.open("bar.txt")?;
+///     let mut file = dir.open("bar.txt")?;
+///     let mut s = String::new();
+///     file.read_to_string(&mut s)?;
+///     println!("{}", s);
 ///     Ok(())
 /// }
 /// ```
+#[unstable(feature = "dirfd", issue = "120426")]
 pub struct Dir {
     inner: fs_imp::Dir,
 }
@@ -1500,10 +1503,8 @@ impl Dir {
     ///
     /// # Errors
     ///
-    /// This function will return an error in these (and other) situations:
-    /// * The path doesn't exist
-    /// * The path doesn't specify a directory
-    /// * The process doesn't have permission to read the directory
+    /// This function will return an error if `path` does not point to an existing directory.
+    /// Other errors may also be returned according to [`OpenOptions::open`].
     ///
     /// # Examples
     ///
@@ -1530,10 +1531,7 @@ impl Dir {
     ///
     /// # Errors
     ///
-    /// This function will return an error in these (and other) situations:
-    /// * The path doesn't exist
-    /// * The path doesn't specify a directory
-    /// * The process doesn't have permission to read/write (according to `opts`) the directory
+    /// This function may return an error according to [`OpenOptions::open`].
     ///
     /// # Examples
     ///
@@ -1556,10 +1554,8 @@ impl Dir {
     ///
     /// # Errors
     ///
-    /// This function will return an error in these (and other) situations:
-    /// * The path doesn't exist
-    /// * The path doesn't specify a regular file
-    /// * The process doesn't have permission to read/write (according to `opts`) the directory
+    /// This function will return an error if `path` does not point to an existing file.
+    /// Other errors may also be returned according to [`OpenOptions::open`].
     ///
     /// # Examples
     ///
@@ -1584,11 +1580,7 @@ impl Dir {
     ///
     /// # Errors
     ///
-    /// This function may return an error in these (and other) situations, depending on the
-    /// specified `opts`:
-    /// * The path doesn't exist
-    /// * The path doesn't specify a regular file
-    /// * The process doesn't have permission to read/write (according to `opts`) the directory
+    /// This function may return an error according to [`OpenOptions::open`].
     ///
     /// # Examples
     ///
@@ -1613,9 +1605,8 @@ impl Dir {
     ///
     /// # Errors
     ///
-    /// This function will return an error in these (and other) situations:
-    /// * The path exists
-    /// * The process doesn't have permission to create the directory
+    /// This function will return an error if `path` points to an existing file or directory.
+    /// Other errors may also be returned according to [`OpenOptions::open`].
     ///
     /// # Examples
     ///
@@ -1640,10 +1631,8 @@ impl Dir {
     ///
     /// # Errors
     ///
-    /// This function will return an error in these (and other) situations:
-    /// * The path doesn't exist
-    /// * The path doesn't specify a regular file
-    /// * The process doesn't have permission to delete the file.
+    /// This function will return an error if `path` does not point to an existing file.
+    /// Other errors may also be returned according to [`OpenOptions::open`].
     ///
     /// # Examples
     ///
@@ -1666,11 +1655,8 @@ impl Dir {
     ///
     /// # Errors
     ///
-    /// This function will return an error in these (and other) situations:
-    /// * The path doesn't exist
-    /// * The path doesn't specify a directory
-    /// * The directory isn't empty
-    /// * The process doesn't have permission to delete the directory.
+    /// This function will return an error if `path` does not point to an existing, non-empty directory.
+    /// Other errors may also be returned according to [`OpenOptions::open`].
     ///
     /// # Examples
     ///
@@ -1694,10 +1680,8 @@ impl Dir {
     ///
     /// # Errors
     ///
-    /// This function will return an error in these (and other) situations:
-    /// * The `from` path doesn't exist
-    /// * The `from` path doesn't specify a directory
-    /// * `self` and `to_dir` are on different mount points
+    /// This function will return an error if `from` does not point to an existing file or directory.
+    /// Other errors may also be returned according to [`OpenOptions::open`].
     ///
     /// # Examples
     ///

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

@@ -1066,19 +1066,21 @@ impl Dir {
         let handle = run_path_with_utf16(from, &|u| self.open_native(u, &opts))?;
         // Calculate the layout of the `FILE_RENAME_INFO` we pass to `SetFileInformation`
         // This is a dynamically sized struct so we need to get the position of the last field to calculate the actual size.
-        let Ok(new_len_without_nul_in_bytes): Result<u32, _> =
-            ((to.count_bytes() - 1) * 2).try_into()
-        else {
-            return Err(io::Error::new(io::ErrorKind::InvalidFilename, "Filename too long"));
-        };
-        let offset: u32 = offset_of!(c::FILE_RENAME_INFO, FileName).try_into().unwrap();
-        let struct_size = offset + new_len_without_nul_in_bytes + 2;
-        let layout =
-            Layout::from_size_align(struct_size as usize, align_of::<c::FILE_RENAME_INFO>())
-                .unwrap();
+        const too_long_err: io::Error =
+            io::const_error!(io::ErrorKind::InvalidFilename, "Filename too long");
+        let struct_size = to
+            .count_bytes()
+            .checked_mul(2)
+            .and_then(|x| x.checked_add(offset_of!(c::FILE_RENAME_INFO, FileName)))
+            .ok_or(too_long_err)?;
+        let layout = Layout::from_size_align(struct_size, align_of::<c::FILE_RENAME_INFO>())
+            .map_err(|_| too_long_err)?;
+        let to_byte_len_without_nul =
+            u32::try_from((to.count_bytes() - 1) * 2).map_err(|_| too_long_err)?;
+        let struct_size = u32::try_from(struct_size).map_err(|_| too_long_err)?;
 
-        // SAFETY: We allocate enough memory for a full FILE_RENAME_INFO struct and a filename.
         let file_rename_info;
+        // SAFETY: We allocate enough memory for a full FILE_RENAME_INFO struct and a filename.
         unsafe {
             file_rename_info = alloc(layout).cast::<c::FILE_RENAME_INFO>();
             if file_rename_info.is_null() {
@@ -1091,7 +1093,7 @@ impl Dir {
 
             (&raw mut (*file_rename_info).RootDirectory).write(to_dir.handle.as_raw_handle());
             // Don't include the NULL in the size
-            (&raw mut (*file_rename_info).FileNameLength).write(new_len_without_nul_in_bytes);
+            (&raw mut (*file_rename_info).FileNameLength).write(to_byte_len_without_nul);
 
             to.as_ptr().copy_to_nonoverlapping(
                 (&raw mut (*file_rename_info).FileName).cast::<u16>(),
@@ -1540,8 +1542,8 @@ pub fn rename(old: &WCStr, new: &WCStr) -> io::Result<()> {
                 Layout::from_size_align(struct_size as usize, align_of::<c::FILE_RENAME_INFO>())
                     .unwrap();
 
-            // SAFETY: We allocate enough memory for a full FILE_RENAME_INFO struct and a filename.
             let file_rename_info;
+            // SAFETY: We allocate enough memory for a full FILE_RENAME_INFO struct and a filename.
             unsafe {
                 file_rename_info = alloc(layout).cast::<c::FILE_RENAME_INFO>();
                 if file_rename_info.is_null() {