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

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

@@ -282,7 +282,7 @@ pub unsafe fn NtReadFile(
     byteoffset: Option<&LARGE_INTEGER>,
     key: Option<&ULONG>,
 ) -> NTSTATUS {
-    windows_sys::NtReadFile(
+    ntdll::NtReadFile(
         filehandle.as_raw_handle(),
         event,
         apcroutine,
@@ -305,7 +305,7 @@ pub unsafe fn NtWriteFile(
     byteoffset: Option<&LARGE_INTEGER>,
     key: Option<&ULONG>,
 ) -> NTSTATUS {
-    windows_sys::NtWriteFile(
+    ntdll::NtWriteFile(
         filehandle.as_raw_handle(),
         event,
         apcroutine,
@@ -565,6 +565,53 @@ pub const RtlGenRandom: unsafe fn(
     randombufferlength: u32,
 ) -> BOOLEAN = SystemFunction036;
 
+compat_fn_lazy! {
+    pub static NTDLL: &CStr = c"ntdll" => { load: true, unicows: false };
+
+    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;
+}
+
+pub mod ntdll {
+    use super::*;
+    compat_fn_lazy! {
+        pub static NTDLL: &CStr = c"ntdll" => { load: true, unicows: false };
+
+        pub fn NtReadFile(
+            filehandle: HANDLE,
+            event: HANDLE,
+            apcroutine: PIO_APC_ROUTINE,
+            apccontext: *const ::core::ffi::c_void,
+            iostatusblock: *mut IO_STATUS_BLOCK,
+            buffer: *mut ::core::ffi::c_void,
+            length: u32,
+            byteoffset: *const i64,
+            key: *const u32,
+        ) -> NTSTATUS;
+        pub fn NtWriteFile(
+            filehandle: HANDLE,
+            event: HANDLE,
+            apcroutine: PIO_APC_ROUTINE,
+            apccontext: *const ::core::ffi::c_void,
+            iostatusblock: *mut IO_STATUS_BLOCK,
+            buffer: *const ::core::ffi::c_void,
+            length: u32,
+            byteoffset: *const i64,
+            key: *const u32,
+        ) -> NTSTATUS;
+    }
+}
 compat_fn_with_fallback! {
     pub static NTDLL: &CStr = c"ntdll" => { load: true, unicows: false };
 
@@ -592,53 +639,6 @@ compat_fn_with_fallback! {
     ) -> NTSTATUS {
         panic!("keyed events not available")
     }
-
-    // These functions are available on UWP when lazily loaded. They will fail WACK if loaded statically.
-    #[cfg(target_vendor = "uwp")]
-    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 {
-        STATUS_NOT_IMPLEMENTED
-    }
-    #[cfg(target_vendor = "uwp")]
-    pub fn NtReadFile(
-        filehandle: BorrowedHandle<'_>,
-        event: HANDLE,
-        apcroutine: PIO_APC_ROUTINE,
-        apccontext: *mut c_void,
-        iostatusblock: &mut IO_STATUS_BLOCK,
-        buffer: *mut crate::mem::MaybeUninit<u8>,
-        length: ULONG,
-        byteoffset: Option<&LARGE_INTEGER>,
-        key: Option<&ULONG>
-    ) -> NTSTATUS {
-        STATUS_NOT_IMPLEMENTED
-    }
-    #[cfg(target_vendor = "uwp")]
-    pub fn NtWriteFile(
-        filehandle: BorrowedHandle<'_>,
-        event: HANDLE,
-        apcroutine: PIO_APC_ROUTINE,
-        apccontext: *mut c_void,
-        iostatusblock: &mut IO_STATUS_BLOCK,
-        buffer: *const u8,
-        length: ULONG,
-        byteoffset: Option<&LARGE_INTEGER>,
-        key: Option<&ULONG>
-    ) -> NTSTATUS {
-        STATUS_NOT_IMPLEMENTED
-    }
-    #[cfg(target_vendor = "uwp")]
     pub fn RtlNtStatusToDosError(Status: NTSTATUS) -> u32 {
         Status as u32
     }

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

@@ -1133,6 +1133,22 @@ 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::option().is_none()
+        || c::GetFileInformationByHandleEx::option().is_none()
+        || c::SetFileInformationByHandle::option().is_none()
+    {
+        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.
@@ -1232,6 +1248,21 @@ 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