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Win: Use FILE_RENAME_FLAG_POSIX_SEMANTICS for std::fs::rename if available

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Windows 10 1601 introduced `FileRenameInfoEx` as well as
`FILE_RENAME_FLAG_POSIX_SEMANTICS`, allowing for atomic renaming. If it
isn't supported, we fall back to `FileRenameInfo`.

This commit also replicates `MoveFileExW`'s behavior of checking whether
the source file is a mount point and moving the mount point instead of
resolving the target path.
This commit is contained in:
George Tokmaji 2024-09-30 19:12:05 +02:00
parent ed04567ba1
commit 1e414f1fff
4 changed files with 168 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

8
library/std/src/fs.rs
View file

@ -2171,12 +2171,14 @@ pub fn symlink_metadata<P: AsRef<Path>>(path: P) -> io::Result<Metadata> {
/// # Platform-specific behavior
///
/// This function currently corresponds to the `rename` function on Unix
/// and the `MoveFileEx` function with the `MOVEFILE_REPLACE_EXISTING` flag on Windows.
/// and the `SetFileInformationByHandle` function on Windows.
///
/// Because of this, the behavior when both `from` and `to` exist differs. On
/// Unix, if `from` is a directory, `to` must also be an (empty) directory. If
/// `from` is not a directory, `to` must also be not a directory. In contrast,
/// on Windows, `from` can be anything, but `to` must *not* be a directory.
/// `from` is not a directory, `to` must also be not a directory. The behavior
/// on Windows is the same on Windows 10 1607 and higher if `FileRenameInfoEx`
/// is supported by the filesystem; otherwise, `from` can be anything, but
/// `to` must *not* be a directory.
///
/// Note that, this [may change in the future][changes].
///

3
library/std/src/sys/pal/windows/c/bindings.txt
View file

@ -2295,6 +2295,7 @@ Windows.Win32.Storage.FileSystem.FILE_NAME_OPENED
Windows.Win32.Storage.FileSystem.FILE_READ_ATTRIBUTES
Windows.Win32.Storage.FileSystem.FILE_READ_DATA
Windows.Win32.Storage.FileSystem.FILE_READ_EA
Windows.Win32.Storage.FileSystem.FILE_RENAME_INFO
Windows.Win32.Storage.FileSystem.FILE_SHARE_DELETE
Windows.Win32.Storage.FileSystem.FILE_SHARE_MODE
Windows.Win32.Storage.FileSystem.FILE_SHARE_NONE
@ -2597,5 +2598,7 @@ Windows.Win32.System.Threading.WaitForMultipleObjects
Windows.Win32.System.Threading.WaitForSingleObject
Windows.Win32.System.Threading.WakeAllConditionVariable
Windows.Win32.System.Threading.WakeConditionVariable
Windows.Win32.System.WindowsProgramming.FILE_RENAME_FLAG_POSIX_SEMANTICS
Windows.Win32.System.WindowsProgramming.FILE_RENAME_FLAG_REPLACE_IF_EXISTS
Windows.Win32.System.WindowsProgramming.PROGRESS_CONTINUE
Windows.Win32.UI.Shell.GetUserProfileDirectoryW

16
library/std/src/sys/pal/windows/c/windows_sys.rs
View file

@ -2470,6 +2470,22 @@ pub const FILE_RANDOM_ACCESS: NTCREATEFILE_CREATE_OPTIONS = 2048u32;
pub const FILE_READ_ATTRIBUTES: FILE_ACCESS_RIGHTS = 128u32;
pub const FILE_READ_DATA: FILE_ACCESS_RIGHTS = 1u32;
pub const FILE_READ_EA: FILE_ACCESS_RIGHTS = 8u32;
pub const FILE_RENAME_FLAG_POSIX_SEMANTICS: u32 = 2u32;
pub const FILE_RENAME_FLAG_REPLACE_IF_EXISTS: u32 = 1u32;
#[repr(C)]
#[derive(Clone, Copy)]
pub struct FILE_RENAME_INFO {
pub Anonymous: FILE_RENAME_INFO_0,
pub RootDirectory: HANDLE,
pub FileNameLength: u32,
pub FileName: [u16; 1],
}
#[repr(C)]
#[derive(Clone, Copy)]
pub union FILE_RENAME_INFO_0 {
pub ReplaceIfExists: BOOLEAN,
pub Flags: u32,
}
pub const FILE_RESERVE_OPFILTER: NTCREATEFILE_CREATE_OPTIONS = 1048576u32;
pub const FILE_SEQUENTIAL_ONLY: NTCREATEFILE_CREATE_OPTIONS = 4u32;
pub const FILE_SESSION_AWARE: NTCREATEFILE_CREATE_OPTIONS = 262144u32;

145
library/std/src/sys/pal/windows/fs.rs
View file

@ -1,5 +1,6 @@
use super::api::{self, WinError};
use super::{IoResult, to_u16s};
use crate::alloc::{alloc, handle_alloc_error};
use crate::borrow::Cow;
use crate::ffi::{OsStr, OsString, c_void};
use crate::io::{self, BorrowedCursor, Error, IoSlice, IoSliceMut, SeekFrom};
@ -1095,7 +1096,149 @@ pub fn unlink(p: &Path) -> io::Result<()> {
pub fn rename(old: &Path, new: &Path) -> io::Result<()> {
let old = maybe_verbatim(old)?;
let new = maybe_verbatim(new)?;
cvt(unsafe { c::MoveFileExW(old.as_ptr(), new.as_ptr(), c::MOVEFILE_REPLACE_EXISTING) })?;
let new_len_without_nul_in_bytes = (new.len() - 1).try_into().unwrap();
let struct_size = mem::size_of::<c::FILE_RENAME_INFO>() - mem::size_of::<u16>()
+ new.len() * mem::size_of::<u16>();
let struct_size: u32 = struct_size.try_into().unwrap();
let create_file = |extra_access, extra_flags| {
let handle = unsafe {
HandleOrInvalid::from_raw_handle(c::CreateFileW(
old.as_ptr(),
c::SYNCHRONIZE | c::DELETE | extra_access,
c::FILE_SHARE_READ | c::FILE_SHARE_WRITE | c::FILE_SHARE_DELETE,
ptr::null(),
c::OPEN_EXISTING,
c::FILE_ATTRIBUTE_NORMAL | c::FILE_FLAG_BACKUP_SEMANTICS | extra_flags,
ptr::null_mut(),
))
};
OwnedHandle::try_from(handle).map_err(|_| io::Error::last_os_error())
};
// The following code replicates `MoveFileEx`'s behavior as reverse-engineered from its disassembly.
// If `old` refers to a mount point, we move it instead of the target.
let handle = match create_file(c::FILE_READ_ATTRIBUTES, c::FILE_FLAG_OPEN_REPARSE_POINT) {
Ok(handle) => {
let mut file_attribute_tag_info: MaybeUninit<c::FILE_ATTRIBUTE_TAG_INFO> =
MaybeUninit::uninit();
let result = unsafe {
cvt(c::GetFileInformationByHandleEx(
handle.as_raw_handle(),
c::FileAttributeTagInfo,
file_attribute_tag_info.as_mut_ptr().cast(),
mem::size_of::<c::FILE_ATTRIBUTE_TAG_INFO>().try_into().unwrap(),
))
};
if let Err(err) = result {
if err.raw_os_error() == Some(c::ERROR_INVALID_PARAMETER as _)
|| err.raw_os_error() == Some(c::ERROR_INVALID_FUNCTION as _)
{
// `GetFileInformationByHandleEx` documents that not all underlying drivers support all file information classes.
// Since we know we passed the correct arguments, this means the underlying driver didn't understand our request;
// `MoveFileEx` proceeds by reopening the file without inhibiting reparse point behavior.
None
} else {
Some(Err(err))
}
} else {
// SAFETY: The struct has been initialized by GetFileInformationByHandleEx
let file_attribute_tag_info = unsafe { file_attribute_tag_info.assume_init() };
if file_attribute_tag_info.FileAttributes & c::FILE_ATTRIBUTE_REPARSE_POINT != 0
&& file_attribute_tag_info.ReparseTag != c::IO_REPARSE_TAG_MOUNT_POINT
{
// The file is not a mount point: Reopen the file without inhibiting reparse point behavior.
None
} else {
// The file is a mount point: Don't reopen the file so that the mount point gets renamed.
Some(Ok(handle))
}
}
}
// The underlying driver may not support `FILE_FLAG_OPEN_REPARSE_POINT`: Retry without it.
Err(err) if err.raw_os_error() == Some(c::ERROR_INVALID_PARAMETER as _) => None,
Err(err) => Some(Err(err)),
}
.unwrap_or_else(|| create_file(0, 0))?;
// The last field of FILE_RENAME_INFO, the file name, is unsized.
// Therefore we need to subtract the size of one wide char.
let layout = core::alloc::Layout::from_size_align(
struct_size as _,
mem::align_of::<c::FILE_RENAME_INFO>(),
)
.unwrap();
let file_rename_info = unsafe { alloc(layout) } as *mut c::FILE_RENAME_INFO;
if file_rename_info.is_null() {
handle_alloc_error(layout);
}
// SAFETY: file_rename_info is a non-null pointer pointing to memory allocated by the global allocator.
let mut file_rename_info = unsafe { Box::from_raw(file_rename_info) };
// SAFETY: We have allocated enough memory for a full FILE_RENAME_INFO struct and a filename.
unsafe {
(&raw mut (*file_rename_info).Anonymous).write(c::FILE_RENAME_INFO_0 {
// Don't bother with FileRenameInfo on Windows 7 since it doesn't exist.
#[cfg(not(target_vendor = "win7"))]
Flags: c::FILE_RENAME_FLAG_REPLACE_IF_EXISTS | c::FILE_RENAME_FLAG_POSIX_SEMANTICS,
#[cfg(target_vendor = "win7")]
ReplaceIfExists: 1,
});
(&raw mut (*file_rename_info).RootDirectory).write(ptr::null_mut());
(&raw mut (*file_rename_info).FileNameLength).write(new_len_without_nul_in_bytes);
new.as_ptr()
.copy_to_nonoverlapping((&raw mut (*file_rename_info).FileName) as *mut u16, new.len());
}
#[cfg(not(target_vendor = "win7"))]
const FileInformationClass: c::FILE_INFO_BY_HANDLE_CLASS = c::FileRenameInfoEx;
#[cfg(target_vendor = "win7")]
const FileInformationClass: c::FILE_INFO_BY_HANDLE_CLASS = c::FileRenameInfo;
// We don't use `set_file_information_by_handle` here as `FILE_RENAME_INFO` is used for both `FileRenameInfo` and `FileRenameInfoEx`.
let result = unsafe {
cvt(c::SetFileInformationByHandle(
handle.as_raw_handle(),
FileInformationClass,
(&raw const *file_rename_info).cast::<c_void>(),
struct_size,
))
};
#[cfg(not(target_vendor = "win7"))]
if let Err(err) = result {
if err.raw_os_error() == Some(c::ERROR_INVALID_PARAMETER as _) {
// FileRenameInfoEx and FILE_RENAME_FLAG_POSIX_SEMANTICS were added in Windows 10 1607; retry with FileRenameInfo.
file_rename_info.Anonymous.ReplaceIfExists = 1;
cvt(unsafe {
c::SetFileInformationByHandle(
handle.as_raw_handle(),
c::FileRenameInfo,
(&raw const *file_rename_info).cast::<c_void>(),
struct_size,
)
})?;
} else {
return Err(err);
}
}
#[cfg(target_vendor = "win7")]
result?;
Ok(())
}