Auto merge of #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.

4 files changed, 41 insertions, 14 deletions

diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index 675140ff18f..8a0d2a7f5cf 100644
--- a/library/std/src/fs.rs
+++ b/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].
 ///
diff --git a/library/std/src/sys/pal/windows/c/bindings.txt b/library/std/src/sys/pal/windows/c/bindings.txt
index 9c2e4500da0..192c95fd203 100644
--- a/library/std/src/sys/pal/windows/c/bindings.txt
+++ b/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
diff --git a/library/std/src/sys/pal/windows/c/windows_sys.rs b/library/std/src/sys/pal/windows/c/windows_sys.rs
index ab5f8919d7a..52444c2c009 100644
--- a/library/std/src/sys/pal/windows/c/windows_sys.rs
+++ b/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 {
diff --git a/library/std/src/sys/pal/windows/fs.rs b/library/std/src/sys/pal/windows/fs.rs
index aab471e28ea..b237fa481e2 100644
--- a/library/std/src/sys/pal/windows/fs.rs
+++ b/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() {