Fall back to old impl for remove_dir_all

The recursive directory removal implementation falls back to the old one
if the necessary APIs are not available (`NtCreateFile`,
`GetFileInformationByHandleEx`, `SetFileInformationByHandle`). The APIs
are available on Vista/Server 2008.

See notes on `fileextd.lib` above to extend the support to Windows
XP/Server 2003. **This might cause security issues**, see
rust-lang#93112

Author: seritools

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

@@ -563,6 +563,18 @@ compat_fn_with_fallback! {
     ) -> COMPARESTRING_RESULT {
         rtabort!("unavailable")
     }
+
+    // >= Vista / Server 2008 (XP / Server 2003 when linking a supported FileExtd.lib)
+    // https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getfileinformationbyhandleex
+    pub fn GetFileInformationByHandleEx(
+        hFile: HANDLE,
+        fileInfoClass: FILE_INFO_BY_HANDLE_CLASS,
+        lpFileInformation: *mut ::core::ffi::c_void,
+        dwBufferSize: u32
+    ) -> BOOL {
+        SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD);
+        FALSE
+    }
 }
 
 compat_fn_optional! {
@@ -579,6 +591,22 @@ compat_fn_optional! {
 compat_fn_with_fallback! {
     pub static NTDLL: &CStr = ansi_str!("ntdll");
 
+    pub fn NtCreateFile(
+        filehandle: *mut HANDLE,
+        desiredaccess: FILE_ACCESS_RIGHTS,
+        objectattributes: *const OBJECT_ATTRIBUTES,
+        iostatusblock: *mut IO_STATUS_BLOCK,
+        allocationsize: *const i64,
+        fileattributes: FILE_FLAGS_AND_ATTRIBUTES,
+        shareaccess: FILE_SHARE_MODE,
+        createdisposition: NTCREATEFILE_CREATE_DISPOSITION,
+        createoptions: NTCREATEFILE_CREATE_OPTIONS,
+        eabuffer: *const ::core::ffi::c_void,
+        ealength: u32,
+    ) -> NTSTATUS {
+        rtabort!("unavailable")
+    }
+
     pub fn NtCreateKeyedEvent(
         KeyedEventHandle: LPHANDLE,
         DesiredAccess: ACCESS_MASK,

library/std/src/sys/windows/c/windows_sys.lst

@@ -28,7 +28,6 @@ Windows.Wdk.Storage.FileSystem.FILE_SUPERSEDE
 Windows.Wdk.Storage.FileSystem.FILE_SYNCHRONOUS_IO_ALERT
 Windows.Wdk.Storage.FileSystem.FILE_SYNCHRONOUS_IO_NONALERT
 Windows.Wdk.Storage.FileSystem.FILE_WRITE_THROUGH
-Windows.Wdk.Storage.FileSystem.NtCreateFile
 Windows.Wdk.Storage.FileSystem.NTCREATEFILE_CREATE_DISPOSITION
 Windows.Wdk.Storage.FileSystem.NTCREATEFILE_CREATE_OPTIONS
 Windows.Wdk.Storage.FileSystem.NtReadFile
@@ -2325,7 +2324,6 @@ Windows.Win32.Storage.FileSystem.FindNextFileW
 Windows.Win32.Storage.FileSystem.FlushFileBuffers
 Windows.Win32.Storage.FileSystem.GetFileAttributesW
 Windows.Win32.Storage.FileSystem.GetFileInformationByHandle
-Windows.Win32.Storage.FileSystem.GetFileInformationByHandleEx
 Windows.Win32.Storage.FileSystem.GetFileType
 Windows.Win32.Storage.FileSystem.GETFINALPATHNAMEBYHANDLE_FLAGS
 Windows.Win32.Storage.FileSystem.GetFullPathNameW

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

@@ -194,15 +194,6 @@ extern "system" {
     ) -> BOOL;
 }
 #[link(name = "kernel32")]
-extern "system" {
-    pub fn GetFileInformationByHandleEx(
-        hfile: HANDLE,
-        fileinformationclass: FILE_INFO_BY_HANDLE_CLASS,
-        lpfileinformation: *mut ::core::ffi::c_void,
-        dwbuffersize: u32,
-    ) -> BOOL;
-}
-#[link(name = "kernel32")]
 extern "system" {
     pub fn GetFileType(hfile: HANDLE) -> FILE_TYPE;
 }
@@ -445,22 +436,6 @@ extern "system" {
     ) -> BOOL;
 }
 #[link(name = "ntdll")]
-extern "system" {
-    pub fn NtCreateFile(
-        filehandle: *mut HANDLE,
-        desiredaccess: FILE_ACCESS_RIGHTS,
-        objectattributes: *const OBJECT_ATTRIBUTES,
-        iostatusblock: *mut IO_STATUS_BLOCK,
-        allocationsize: *const i64,
-        fileattributes: FILE_FLAGS_AND_ATTRIBUTES,
-        shareaccess: FILE_SHARE_MODE,
-        createdisposition: NTCREATEFILE_CREATE_DISPOSITION,
-        createoptions: NTCREATEFILE_CREATE_OPTIONS,
-        eabuffer: *const ::core::ffi::c_void,
-        ealength: u32,
-    ) -> NTSTATUS;
-}
-#[link(name = "ntdll")]
 extern "system" {
     pub fn NtReadFile(
         filehandle: HANDLE,

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

@@ -1161,6 +1161,22 @@ fn open_link(path: &Path, access_mode: u32) -> io::Result<File> {
 }
 
 pub fn remove_dir_all(path: &Path) -> io::Result<()> {
+    // if the modern file/directory APIs are not available, we'll fall back to the old (unsafe, see
+    // https://github.com/rust-lang/rust/pull/93112) directory removal implementation
+    if !c::NtCreateFile::available()
+        || !c::GetFileInformationByHandleEx::available()
+        || !c::SetFileInformationByHandle::available()
+    {
+        let filetype = lstat(path)?.file_type();
+        if filetype.is_symlink() {
+            // On Windows symlinks to files and directories are removed differently.
+            // rmdir only deletes dir symlinks and junctions, not file symlinks.
+            return rmdir(path);
+        } else {
+            return remove_dir_all_recursive_old(path);
+        }
+    }
+
     let file = open_link(path, c::DELETE | c::FILE_LIST_DIRECTORY)?;
 
     // Test if the file is not a directory or a symlink to a directory.
@@ -1260,6 +1276,21 @@ fn remove_dir_all_iterative(f: &File, delete: fn(&File) -> io::Result<()>) -> io
     Ok(())
 }
 
+fn remove_dir_all_recursive_old(path: &Path) -> io::Result<()> {
+    for child in readdir(path)? {
+        let child = child?;
+        let child_type = child.file_type()?;
+        if child_type.is_dir() {
+            remove_dir_all_recursive_old(&child.path())?;
+        } else if child_type.is_symlink_dir() {
+            rmdir(&child.path())?;
+        } else {
+            unlink(&child.path())?;
+        }
+    }
+    rmdir(path)
+}
+
 pub fn readlink(path: &Path) -> io::Result<PathBuf> {
     // Open the link with no access mode, instead of generic read.
     // By default FILE_LIST_DIRECTORY is denied for the junction "C:\Documents and Settings", so