Auto merge of rust-lang#131972 - klensy:FindFirstFileExW, r=ChrisDenton

speedup directory traversal on windows

Optimizes walking over dirs on windows by replacing `FindFirstFileW` with `FindFirstFileExW` with `FindExInfoBasic` option, that allows skipping filling unused struct field which should be faster.

Also adds the same change for fallback call of `FindFirstFileExW` in metadata call.

Locally shows small speedup, but bench results from other users are welcome.

library/std/src/fs.rs

@@ -2618,7 +2618,7 @@ pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
 /// # Platform-specific behavior
 ///
 /// This function currently corresponds to the `opendir` function on Unix
-/// and the `FindFirstFile` function on Windows. Advancing the iterator
+/// and the `FindFirstFileEx` function on Windows. Advancing the iterator
 /// currently corresponds to `readdir` on Unix and `FindNextFile` on Windows.
 /// Note that, this [may change in the future][changes].
 ///

library/std/src/sys/pal/windows/c/bindings.txt

@@ -2337,7 +2337,9 @@ Windows.Win32.Storage.FileSystem.FileStandardInfo
 Windows.Win32.Storage.FileSystem.FileStorageInfo
 Windows.Win32.Storage.FileSystem.FileStreamInfo
 Windows.Win32.Storage.FileSystem.FindClose
-Windows.Win32.Storage.FileSystem.FindFirstFileW
+Windows.Win32.Storage.FileSystem.FindExInfoBasic
+Windows.Win32.Storage.FileSystem.FindExSearchNameMatch
+Windows.Win32.Storage.FileSystem.FindFirstFileExW
 Windows.Win32.Storage.FileSystem.FindNextFileW
 Windows.Win32.Storage.FileSystem.FlushFileBuffers
 Windows.Win32.Storage.FileSystem.GetFileAttributesW

library/std/src/sys/pal/windows/c/windows_sys.rs

@@ -26,7 +26,7 @@ windows_targets::link!("kernel32.dll" "system" fn DeviceIoControl(hdevice : HAND
 windows_targets::link!("kernel32.dll" "system" fn DuplicateHandle(hsourceprocesshandle : HANDLE, hsourcehandle : HANDLE, htargetprocesshandle : HANDLE, lptargethandle : *mut HANDLE, dwdesiredaccess : u32, binherithandle : BOOL, dwoptions : DUPLICATE_HANDLE_OPTIONS) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn ExitProcess(uexitcode : u32) -> !);
 windows_targets::link!("kernel32.dll" "system" fn FindClose(hfindfile : HANDLE) -> BOOL);
-windows_targets::link!("kernel32.dll" "system" fn FindFirstFileW(lpfilename : PCWSTR, lpfindfiledata : *mut WIN32_FIND_DATAW) -> HANDLE);
+windows_targets::link!("kernel32.dll" "system" fn FindFirstFileExW(lpfilename : PCWSTR, finfolevelid : FINDEX_INFO_LEVELS, lpfindfiledata : *mut core::ffi::c_void, fsearchop : FINDEX_SEARCH_OPS, lpsearchfilter : *const core::ffi::c_void, dwadditionalflags : FIND_FIRST_EX_FLAGS) -> HANDLE);
 windows_targets::link!("kernel32.dll" "system" fn FindNextFileW(hfindfile : HANDLE, lpfindfiledata : *mut WIN32_FIND_DATAW) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn FlushFileBuffers(hfile : HANDLE) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn FormatMessageW(dwflags : FORMAT_MESSAGE_OPTIONS, lpsource : *const core::ffi::c_void, dwmessageid : u32, dwlanguageid : u32, lpbuffer : PWSTR, nsize : u32, arguments : *const *const i8) -> u32);
@@ -2501,6 +2501,9 @@ pub const FILE_WRITE_ATTRIBUTES: FILE_ACCESS_RIGHTS = 256u32;
 pub const FILE_WRITE_DATA: FILE_ACCESS_RIGHTS = 2u32;
 pub const FILE_WRITE_EA: FILE_ACCESS_RIGHTS = 16u32;
 pub const FILE_WRITE_THROUGH: NTCREATEFILE_CREATE_OPTIONS = 2u32;
+pub type FINDEX_INFO_LEVELS = i32;
+pub type FINDEX_SEARCH_OPS = i32;
+pub type FIND_FIRST_EX_FLAGS = u32;
 pub const FIONBIO: i32 = -2147195266i32;
 #[repr(C)]
 #[cfg(any(target_arch = "aarch64", target_arch = "arm64ec", target_arch = "x86_64"))]
@@ -2565,6 +2568,8 @@ pub const FileRenameInfoEx: FILE_INFO_BY_HANDLE_CLASS = 22i32;
 pub const FileStandardInfo: FILE_INFO_BY_HANDLE_CLASS = 1i32;
 pub const FileStorageInfo: FILE_INFO_BY_HANDLE_CLASS = 16i32;
 pub const FileStreamInfo: FILE_INFO_BY_HANDLE_CLASS = 7i32;
+pub const FindExInfoBasic: FINDEX_INFO_LEVELS = 1i32;
+pub const FindExSearchNameMatch: FINDEX_SEARCH_OPS = 0i32;
 pub type GENERIC_ACCESS_RIGHTS = u32;
 pub const GENERIC_ALL: GENERIC_ACCESS_RIGHTS = 268435456u32;
 pub const GENERIC_EXECUTE: GENERIC_ACCESS_RIGHTS = 536870912u32;
@@ -3307,7 +3312,6 @@ pub struct XSAVE_FORMAT {
  pub XmmRegisters: [M128A; 8],
  pub Reserved4: [u8; 224],
 }
-
 #[cfg(target_arch = "arm")]
 #[repr(C)]
 pub struct WSADATA {

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

@@ -114,7 +114,7 @@ impl Iterator for ReadDir {
  fn next(&mut self) -> Option<io::Result<DirEntry>> {
  if self.handle.0 == c::INVALID_HANDLE_VALUE {
  // This iterator was initialized with an `INVALID_HANDLE_VALUE` as its handle.
- // Simply return `None` because this is only the case when `FindFirstFileW` in
+ // Simply return `None` because this is only the case when `FindFirstFileExW` in
  // the construction of this iterator returns `ERROR_FILE_NOT_FOUND` which means
  // no matchhing files can be found.
  return None;
@@ -1047,8 +1047,22 @@ pub fn readdir(p: &Path) -> io::Result<ReadDir> {
  let path = maybe_verbatim(&star)?;
 
  unsafe {
- let mut wfd = mem::zeroed();
- let find_handle = c::FindFirstFileW(path.as_ptr(), &mut wfd);
+ let mut wfd: c::WIN32_FIND_DATAW = mem::zeroed();
+ // this is like FindFirstFileW (see https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-findfirstfileexw),
+ // but with FindExInfoBasic it should skip filling WIN32_FIND_DATAW.cAlternateFileName
+ // (see https://learn.microsoft.com/en-us/windows/win32/api/minwinbase/ns-minwinbase-win32_find_dataw)
+ // (which will be always null string value and currently unused) and should be faster.
+ //
+ // We can pass FIND_FIRST_EX_LARGE_FETCH to dwAdditionalFlags to speed up things more,
+ // but as we don't know user's use profile of this function, lets be conservative.
+ let find_handle = c::FindFirstFileExW(
+ path.as_ptr(),
+ c::FindExInfoBasic,
+ &mut wfd as *mut _ as _,
+ c::FindExSearchNameMatch,
+ ptr::null(),
+ 0,
+ );
 
  if find_handle != c::INVALID_HANDLE_VALUE {
  Ok(ReadDir {
@@ -1057,7 +1071,7 @@ pub fn readdir(p: &Path) -> io::Result<ReadDir> {
  first: Some(wfd),
  })
  } else {
- // The status `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function
+ // The status `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileExW` function
  // if no matching files can be found, but not necessarily that the path to find the
  // files in does not exist.
  //
@@ -1079,7 +1093,7 @@ pub fn readdir(p: &Path) -> io::Result<ReadDir> {
 
  // Just return the error constructed from the raw OS error if the above is not the case.
  //
- // Note: `ERROR_PATH_NOT_FOUND` would have been returned by the `FindFirstFileW` function
+ // Note: `ERROR_PATH_NOT_FOUND` would have been returned by the `FindFirstFileExW` function
  // when the path to search in does not exist in the first place.
  Err(Error::from_raw_os_error(last_error.code as i32))
  }
@@ -1220,7 +1234,7 @@ fn metadata(path: &Path, reparse: ReparsePoint) -> io::Result<FileAttr> {
  opts.custom_flags(c::FILE_FLAG_BACKUP_SEMANTICS | reparse.as_flag());
 
  // Attempt to open the file normally.
- // If that fails with `ERROR_SHARING_VIOLATION` then retry using `FindFirstFileW`.
+ // If that fails with `ERROR_SHARING_VIOLATION` then retry using `FindFirstFileExW`.
  // If the fallback fails for any reason we return the original error.
  match File::open(path, &opts) {
  Ok(file) => file.file_attr(),
@@ -1237,13 +1251,20 @@ fn metadata(path: &Path, reparse: ReparsePoint) -> io::Result<FileAttr> {
  unsafe {
  let path = maybe_verbatim(path)?;
 
- // `FindFirstFileW` accepts wildcard file names.
+ // `FindFirstFileExW` accepts wildcard file names.
  // Fortunately wildcards are not valid file names and
  // `ERROR_SHARING_VIOLATION` means the file exists (but is locked)
  // therefore it's safe to assume the file name given does not
  // include wildcards.
- let mut wfd = mem::zeroed();
- let handle = c::FindFirstFileW(path.as_ptr(), &mut wfd);
+ let mut wfd: c::WIN32_FIND_DATAW = mem::zeroed();
+ let handle = c::FindFirstFileExW(
+ path.as_ptr(),
+ c::FindExInfoBasic,
+ &mut wfd as *mut _ as _,
+ c::FindExSearchNameMatch,
+ ptr::null(),
+ 0,
+ );
 
  if handle == c::INVALID_HANDLE_VALUE {
  // This can fail if the user does not have read access to the
@@ -1253,7 +1274,7 @@ fn metadata(path: &Path, reparse: ReparsePoint) -> io::Result<FileAttr> {
  // We no longer need the find handle.
  c::FindClose(handle);
 
- // `FindFirstFileW` reads the cached file information from the
+ // `FindFirstFileExW` reads the cached file information from the
  // directory. The downside is that this metadata may be outdated.
  let attrs = FileAttr::from(wfd);
  if reparse == ReparsePoint::Follow && attrs.file_type().is_symlink() {