rust/library/std/src/sys/pal/windows/fs.rs
2024-08-31 12:19:42 +00:00

1452 lines
51 KiB
Rust

use core::ptr::addr_of;
use super::api::{self, WinError};
use super::{to_u16s, IoResult};
use crate::borrow::Cow;
use crate::ffi::{c_void, OsStr, OsString};
use crate::io::{self, BorrowedCursor, Error, IoSlice, IoSliceMut, SeekFrom};
use crate::mem::{self, MaybeUninit};
use crate::os::windows::io::{AsHandle, BorrowedHandle};
use crate::os::windows::prelude::*;
use crate::path::{Path, PathBuf};
use crate::sync::Arc;
use crate::sys::handle::Handle;
use crate::sys::path::maybe_verbatim;
use crate::sys::time::SystemTime;
use crate::sys::{c, cvt, Align8};
use crate::sys_common::{AsInner, FromInner, IntoInner};
use crate::{fmt, ptr, slice};
mod remove_dir_all;
use remove_dir_all::remove_dir_all_iterative;
pub struct File {
handle: Handle,
}
#[derive(Clone)]
pub struct FileAttr {
attributes: u32,
creation_time: c::FILETIME,
last_access_time: c::FILETIME,
last_write_time: c::FILETIME,
change_time: Option<c::FILETIME>,
file_size: u64,
reparse_tag: u32,
volume_serial_number: Option<u32>,
number_of_links: Option<u32>,
file_index: Option<u64>,
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
pub struct FileType {
attributes: u32,
reparse_tag: u32,
}
pub struct ReadDir {
handle: FindNextFileHandle,
root: Arc<PathBuf>,
first: Option<c::WIN32_FIND_DATAW>,
}
struct FindNextFileHandle(c::HANDLE);
unsafe impl Send for FindNextFileHandle {}
unsafe impl Sync for FindNextFileHandle {}
pub struct DirEntry {
root: Arc<PathBuf>,
data: c::WIN32_FIND_DATAW,
}
unsafe impl Send for OpenOptions {}
unsafe impl Sync for OpenOptions {}
#[derive(Clone, Debug)]
pub struct OpenOptions {
// generic
read: bool,
write: bool,
append: bool,
truncate: bool,
create: bool,
create_new: bool,
// system-specific
custom_flags: u32,
access_mode: Option<u32>,
attributes: u32,
share_mode: u32,
security_qos_flags: u32,
security_attributes: *mut c::SECURITY_ATTRIBUTES,
}
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct FilePermissions {
attrs: u32,
}
#[derive(Copy, Clone, Debug, Default)]
pub struct FileTimes {
accessed: Option<c::FILETIME>,
modified: Option<c::FILETIME>,
created: Option<c::FILETIME>,
}
impl fmt::Debug for c::FILETIME {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let time = ((self.dwHighDateTime as u64) << 32) | self.dwLowDateTime as u64;
f.debug_tuple("FILETIME").field(&time).finish()
}
}
#[derive(Debug)]
pub struct DirBuilder;
impl fmt::Debug for ReadDir {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// This will only be called from std::fs::ReadDir, which will add a "ReadDir()" frame.
// Thus the result will be e g 'ReadDir("C:\")'
fmt::Debug::fmt(&*self.root, f)
}
}
impl Iterator for ReadDir {
type Item = io::Result<DirEntry>;
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
// the construction of this iterator returns `ERROR_FILE_NOT_FOUND` which means
// no matchhing files can be found.
return None;
}
if let Some(first) = self.first.take() {
if let Some(e) = DirEntry::new(&self.root, &first) {
return Some(Ok(e));
}
}
unsafe {
let mut wfd = mem::zeroed();
loop {
if c::FindNextFileW(self.handle.0, &mut wfd) == 0 {
match api::get_last_error() {
WinError::NO_MORE_FILES => return None,
WinError { code } => {
return Some(Err(Error::from_raw_os_error(code as i32)));
}
}
}
if let Some(e) = DirEntry::new(&self.root, &wfd) {
return Some(Ok(e));
}
}
}
}
}
impl Drop for FindNextFileHandle {
fn drop(&mut self) {
let r = unsafe { c::FindClose(self.0) };
debug_assert!(r != 0);
}
}
impl DirEntry {
fn new(root: &Arc<PathBuf>, wfd: &c::WIN32_FIND_DATAW) -> Option<DirEntry> {
match &wfd.cFileName[0..3] {
// check for '.' and '..'
&[46, 0, ..] | &[46, 46, 0, ..] => return None,
_ => {}
}
Some(DirEntry { root: root.clone(), data: *wfd })
}
pub fn path(&self) -> PathBuf {
self.root.join(self.file_name())
}
pub fn file_name(&self) -> OsString {
let filename = super::truncate_utf16_at_nul(&self.data.cFileName);
OsString::from_wide(filename)
}
pub fn file_type(&self) -> io::Result<FileType> {
Ok(FileType::new(
self.data.dwFileAttributes,
/* reparse_tag = */ self.data.dwReserved0,
))
}
pub fn metadata(&self) -> io::Result<FileAttr> {
Ok(self.data.into())
}
}
impl OpenOptions {
pub fn new() -> OpenOptions {
OpenOptions {
// generic
read: false,
write: false,
append: false,
truncate: false,
create: false,
create_new: false,
// system-specific
custom_flags: 0,
access_mode: None,
share_mode: c::FILE_SHARE_READ | c::FILE_SHARE_WRITE | c::FILE_SHARE_DELETE,
attributes: 0,
security_qos_flags: 0,
security_attributes: ptr::null_mut(),
}
}
pub fn read(&mut self, read: bool) {
self.read = read;
}
pub fn write(&mut self, write: bool) {
self.write = write;
}
pub fn append(&mut self, append: bool) {
self.append = append;
}
pub fn truncate(&mut self, truncate: bool) {
self.truncate = truncate;
}
pub fn create(&mut self, create: bool) {
self.create = create;
}
pub fn create_new(&mut self, create_new: bool) {
self.create_new = create_new;
}
pub fn custom_flags(&mut self, flags: u32) {
self.custom_flags = flags;
}
pub fn access_mode(&mut self, access_mode: u32) {
self.access_mode = Some(access_mode);
}
pub fn share_mode(&mut self, share_mode: u32) {
self.share_mode = share_mode;
}
pub fn attributes(&mut self, attrs: u32) {
self.attributes = attrs;
}
pub fn security_qos_flags(&mut self, flags: u32) {
// We have to set `SECURITY_SQOS_PRESENT` here, because one of the valid flags we can
// receive is `SECURITY_ANONYMOUS = 0x0`, which we can't check for later on.
self.security_qos_flags = flags | c::SECURITY_SQOS_PRESENT;
}
pub fn security_attributes(&mut self, attrs: *mut c::SECURITY_ATTRIBUTES) {
self.security_attributes = attrs;
}
fn get_access_mode(&self) -> io::Result<u32> {
match (self.read, self.write, self.append, self.access_mode) {
(.., Some(mode)) => Ok(mode),
(true, false, false, None) => Ok(c::GENERIC_READ),
(false, true, false, None) => Ok(c::GENERIC_WRITE),
(true, true, false, None) => Ok(c::GENERIC_READ | c::GENERIC_WRITE),
(false, _, true, None) => Ok(c::FILE_GENERIC_WRITE & !c::FILE_WRITE_DATA),
(true, _, true, None) => {
Ok(c::GENERIC_READ | (c::FILE_GENERIC_WRITE & !c::FILE_WRITE_DATA))
}
(false, false, false, None) => {
Err(Error::from_raw_os_error(c::ERROR_INVALID_PARAMETER as i32))
}
}
}
fn get_creation_mode(&self) -> io::Result<u32> {
match (self.write, self.append) {
(true, false) => {}
(false, false) => {
if self.truncate || self.create || self.create_new {
return Err(Error::from_raw_os_error(c::ERROR_INVALID_PARAMETER as i32));
}
}
(_, true) => {
if self.truncate && !self.create_new {
return Err(Error::from_raw_os_error(c::ERROR_INVALID_PARAMETER as i32));
}
}
}
Ok(match (self.create, self.truncate, self.create_new) {
(false, false, false) => c::OPEN_EXISTING,
(true, false, false) => c::OPEN_ALWAYS,
(false, true, false) => c::TRUNCATE_EXISTING,
// `CREATE_ALWAYS` has weird semantics so we emulate it using
// `OPEN_ALWAYS` and a manual truncation step. See #115745.
(true, true, false) => c::OPEN_ALWAYS,
(_, _, true) => c::CREATE_NEW,
})
}
fn get_flags_and_attributes(&self) -> u32 {
self.custom_flags
| self.attributes
| self.security_qos_flags
| if self.create_new { c::FILE_FLAG_OPEN_REPARSE_POINT } else { 0 }
}
}
impl File {
pub fn open(path: &Path, opts: &OpenOptions) -> io::Result<File> {
let path = maybe_verbatim(path)?;
let creation = opts.get_creation_mode()?;
let handle = unsafe {
c::CreateFileW(
path.as_ptr(),
opts.get_access_mode()?,
opts.share_mode,
opts.security_attributes,
creation,
opts.get_flags_and_attributes(),
ptr::null_mut(),
)
};
let handle = unsafe { HandleOrInvalid::from_raw_handle(handle) };
if let Ok(handle) = OwnedHandle::try_from(handle) {
// Manual truncation. See #115745.
if opts.truncate
&& creation == c::OPEN_ALWAYS
&& api::get_last_error() == WinError::ALREADY_EXISTS
{
unsafe {
// This originally used `FileAllocationInfo` instead of
// `FileEndOfFileInfo` but that wasn't supported by WINE.
// It's arguable which fits the semantics of `OpenOptions`
// better so let's just use the more widely supported method.
let eof = c::FILE_END_OF_FILE_INFO { EndOfFile: 0 };
let result = c::SetFileInformationByHandle(
handle.as_raw_handle(),
c::FileEndOfFileInfo,
ptr::addr_of!(eof).cast::<c_void>(),
mem::size_of::<c::FILE_END_OF_FILE_INFO>() as u32,
);
if result == 0 {
return Err(io::Error::last_os_error());
}
}
}
Ok(File { handle: Handle::from_inner(handle) })
} else {
Err(Error::last_os_error())
}
}
pub fn fsync(&self) -> io::Result<()> {
cvt(unsafe { c::FlushFileBuffers(self.handle.as_raw_handle()) })?;
Ok(())
}
pub fn datasync(&self) -> io::Result<()> {
self.fsync()
}
pub fn truncate(&self, size: u64) -> io::Result<()> {
let info = c::FILE_END_OF_FILE_INFO { EndOfFile: size as i64 };
api::set_file_information_by_handle(self.handle.as_raw_handle(), &info).io_result()
}
#[cfg(not(target_vendor = "uwp"))]
pub fn file_attr(&self) -> io::Result<FileAttr> {
unsafe {
let mut info: c::BY_HANDLE_FILE_INFORMATION = mem::zeroed();
cvt(c::GetFileInformationByHandle(self.handle.as_raw_handle(), &mut info))?;
let mut reparse_tag = 0;
if info.dwFileAttributes & c::FILE_ATTRIBUTE_REPARSE_POINT != 0 {
let mut attr_tag: c::FILE_ATTRIBUTE_TAG_INFO = mem::zeroed();
cvt(c::GetFileInformationByHandleEx(
self.handle.as_raw_handle(),
c::FileAttributeTagInfo,
ptr::addr_of_mut!(attr_tag).cast(),
mem::size_of::<c::FILE_ATTRIBUTE_TAG_INFO>().try_into().unwrap(),
))?;
if attr_tag.FileAttributes & c::FILE_ATTRIBUTE_REPARSE_POINT != 0 {
reparse_tag = attr_tag.ReparseTag;
}
}
Ok(FileAttr {
attributes: info.dwFileAttributes,
creation_time: info.ftCreationTime,
last_access_time: info.ftLastAccessTime,
last_write_time: info.ftLastWriteTime,
change_time: None, // Only available in FILE_BASIC_INFO
file_size: (info.nFileSizeLow as u64) | ((info.nFileSizeHigh as u64) << 32),
reparse_tag,
volume_serial_number: Some(info.dwVolumeSerialNumber),
number_of_links: Some(info.nNumberOfLinks),
file_index: Some(
(info.nFileIndexLow as u64) | ((info.nFileIndexHigh as u64) << 32),
),
})
}
}
#[cfg(target_vendor = "uwp")]
pub fn file_attr(&self) -> io::Result<FileAttr> {
unsafe {
let mut info: c::FILE_BASIC_INFO = mem::zeroed();
let size = mem::size_of_val(&info);
cvt(c::GetFileInformationByHandleEx(
self.handle.as_raw_handle(),
c::FileBasicInfo,
core::ptr::addr_of_mut!(info) as *mut c_void,
size as u32,
))?;
let mut attr = FileAttr {
attributes: info.FileAttributes,
creation_time: c::FILETIME {
dwLowDateTime: info.CreationTime as u32,
dwHighDateTime: (info.CreationTime >> 32) as u32,
},
last_access_time: c::FILETIME {
dwLowDateTime: info.LastAccessTime as u32,
dwHighDateTime: (info.LastAccessTime >> 32) as u32,
},
last_write_time: c::FILETIME {
dwLowDateTime: info.LastWriteTime as u32,
dwHighDateTime: (info.LastWriteTime >> 32) as u32,
},
change_time: Some(c::FILETIME {
dwLowDateTime: info.ChangeTime as u32,
dwHighDateTime: (info.ChangeTime >> 32) as u32,
}),
file_size: 0,
reparse_tag: 0,
volume_serial_number: None,
number_of_links: None,
file_index: None,
};
let mut info: c::FILE_STANDARD_INFO = mem::zeroed();
let size = mem::size_of_val(&info);
cvt(c::GetFileInformationByHandleEx(
self.handle.as_raw_handle(),
c::FileStandardInfo,
core::ptr::addr_of_mut!(info) as *mut c_void,
size as u32,
))?;
attr.file_size = info.AllocationSize as u64;
attr.number_of_links = Some(info.NumberOfLinks);
if attr.file_type().is_reparse_point() {
let mut attr_tag: c::FILE_ATTRIBUTE_TAG_INFO = mem::zeroed();
cvt(c::GetFileInformationByHandleEx(
self.handle.as_raw_handle(),
c::FileAttributeTagInfo,
ptr::addr_of_mut!(attr_tag).cast(),
mem::size_of::<c::FILE_ATTRIBUTE_TAG_INFO>().try_into().unwrap(),
))?;
if attr_tag.FileAttributes & c::FILE_ATTRIBUTE_REPARSE_POINT != 0 {
attr.reparse_tag = attr_tag.ReparseTag;
}
}
Ok(attr)
}
}
pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
self.handle.read(buf)
}
pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
self.handle.read_vectored(bufs)
}
#[inline]
pub fn is_read_vectored(&self) -> bool {
self.handle.is_read_vectored()
}
pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
self.handle.read_at(buf, offset)
}
pub fn read_buf(&self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
self.handle.read_buf(cursor)
}
pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
self.handle.write(buf)
}
pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
self.handle.write_vectored(bufs)
}
#[inline]
pub fn is_write_vectored(&self) -> bool {
self.handle.is_write_vectored()
}
pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
self.handle.write_at(buf, offset)
}
pub fn flush(&self) -> io::Result<()> {
Ok(())
}
pub fn seek(&self, pos: SeekFrom) -> io::Result<u64> {
let (whence, pos) = match pos {
// Casting to `i64` is fine, `SetFilePointerEx` reinterprets this
// integer as `u64`.
SeekFrom::Start(n) => (c::FILE_BEGIN, n as i64),
SeekFrom::End(n) => (c::FILE_END, n),
SeekFrom::Current(n) => (c::FILE_CURRENT, n),
};
let pos = pos as i64;
let mut newpos = 0;
cvt(unsafe { c::SetFilePointerEx(self.handle.as_raw_handle(), pos, &mut newpos, whence) })?;
Ok(newpos as u64)
}
pub fn duplicate(&self) -> io::Result<File> {
Ok(Self { handle: self.handle.try_clone()? })
}
// NB: returned pointer is derived from `space`, and has provenance to
// match. A raw pointer is returned rather than a reference in order to
// avoid narrowing provenance to the actual `REPARSE_DATA_BUFFER`.
fn reparse_point(
&self,
space: &mut Align8<[MaybeUninit<u8>]>,
) -> io::Result<(u32, *mut c::REPARSE_DATA_BUFFER)> {
unsafe {
let mut bytes = 0;
cvt({
// Grab this in advance to avoid it invalidating the pointer
// we get from `space.0.as_mut_ptr()`.
let len = space.0.len();
c::DeviceIoControl(
self.handle.as_raw_handle(),
c::FSCTL_GET_REPARSE_POINT,
ptr::null_mut(),
0,
space.0.as_mut_ptr().cast(),
len as u32,
&mut bytes,
ptr::null_mut(),
)
})?;
const _: () = assert!(core::mem::align_of::<c::REPARSE_DATA_BUFFER>() <= 8);
Ok((bytes, space.0.as_mut_ptr().cast::<c::REPARSE_DATA_BUFFER>()))
}
}
fn readlink(&self) -> io::Result<PathBuf> {
let mut space =
Align8([MaybeUninit::<u8>::uninit(); c::MAXIMUM_REPARSE_DATA_BUFFER_SIZE as usize]);
let (_bytes, buf) = self.reparse_point(&mut space)?;
unsafe {
let (path_buffer, subst_off, subst_len, relative) = match (*buf).ReparseTag {
c::IO_REPARSE_TAG_SYMLINK => {
let info: *mut c::SYMBOLIC_LINK_REPARSE_BUFFER =
ptr::addr_of_mut!((*buf).rest).cast();
assert!(info.is_aligned());
(
ptr::addr_of_mut!((*info).PathBuffer).cast::<u16>(),
(*info).SubstituteNameOffset / 2,
(*info).SubstituteNameLength / 2,
(*info).Flags & c::SYMLINK_FLAG_RELATIVE != 0,
)
}
c::IO_REPARSE_TAG_MOUNT_POINT => {
let info: *mut c::MOUNT_POINT_REPARSE_BUFFER =
ptr::addr_of_mut!((*buf).rest).cast();
assert!(info.is_aligned());
(
ptr::addr_of_mut!((*info).PathBuffer).cast::<u16>(),
(*info).SubstituteNameOffset / 2,
(*info).SubstituteNameLength / 2,
false,
)
}
_ => {
return Err(io::const_io_error!(
io::ErrorKind::Uncategorized,
"Unsupported reparse point type",
));
}
};
let subst_ptr = path_buffer.add(subst_off.into());
let subst = slice::from_raw_parts_mut(subst_ptr, subst_len as usize);
// Absolute paths start with an NT internal namespace prefix `\??\`
// We should not let it leak through.
if !relative && subst.starts_with(&[92u16, 63u16, 63u16, 92u16]) {
// Turn `\??\` into `\\?\` (a verbatim path).
subst[1] = b'\\' as u16;
// Attempt to convert to a more user-friendly path.
let user = super::args::from_wide_to_user_path(
subst.iter().copied().chain([0]).collect(),
)?;
Ok(PathBuf::from(OsString::from_wide(user.strip_suffix(&[0]).unwrap_or(&user))))
} else {
Ok(PathBuf::from(OsString::from_wide(subst)))
}
}
}
pub fn set_permissions(&self, perm: FilePermissions) -> io::Result<()> {
let info = c::FILE_BASIC_INFO {
CreationTime: 0,
LastAccessTime: 0,
LastWriteTime: 0,
ChangeTime: 0,
FileAttributes: perm.attrs,
};
api::set_file_information_by_handle(self.handle.as_raw_handle(), &info).io_result()
}
pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
let is_zero = |t: c::FILETIME| t.dwLowDateTime == 0 && t.dwHighDateTime == 0;
if times.accessed.map_or(false, is_zero)
|| times.modified.map_or(false, is_zero)
|| times.created.map_or(false, is_zero)
{
return Err(io::const_io_error!(
io::ErrorKind::InvalidInput,
"Cannot set file timestamp to 0",
));
}
let is_max = |t: c::FILETIME| t.dwLowDateTime == u32::MAX && t.dwHighDateTime == u32::MAX;
if times.accessed.map_or(false, is_max)
|| times.modified.map_or(false, is_max)
|| times.created.map_or(false, is_max)
{
return Err(io::const_io_error!(
io::ErrorKind::InvalidInput,
"Cannot set file timestamp to 0xFFFF_FFFF_FFFF_FFFF",
));
}
cvt(unsafe {
let created =
times.created.as_ref().map(|a| a as *const c::FILETIME).unwrap_or(ptr::null());
let accessed =
times.accessed.as_ref().map(|a| a as *const c::FILETIME).unwrap_or(ptr::null());
let modified =
times.modified.as_ref().map(|a| a as *const c::FILETIME).unwrap_or(ptr::null());
c::SetFileTime(self.as_raw_handle(), created, accessed, modified)
})?;
Ok(())
}
/// Gets only basic file information such as attributes and file times.
fn basic_info(&self) -> io::Result<c::FILE_BASIC_INFO> {
unsafe {
let mut info: c::FILE_BASIC_INFO = mem::zeroed();
let size = mem::size_of_val(&info);
cvt(c::GetFileInformationByHandleEx(
self.handle.as_raw_handle(),
c::FileBasicInfo,
core::ptr::addr_of_mut!(info) as *mut c_void,
size as u32,
))?;
Ok(info)
}
}
/// Deletes the file, consuming the file handle to ensure the delete occurs
/// as immediately as possible.
/// This attempts to use `posix_delete` but falls back to `win32_delete`
/// if that is not supported by the filesystem.
#[allow(unused)]
fn delete(self) -> Result<(), WinError> {
// If POSIX delete is not supported for this filesystem then fallback to win32 delete.
match self.posix_delete() {
Err(WinError::INVALID_PARAMETER)
| Err(WinError::NOT_SUPPORTED)
| Err(WinError::INVALID_FUNCTION) => self.win32_delete(),
result => result,
}
}
/// Delete using POSIX semantics.
///
/// Files will be deleted as soon as the handle is closed. This is supported
/// for Windows 10 1607 (aka RS1) and later. However some filesystem
/// drivers will not support it even then, e.g. FAT32.
///
/// If the operation is not supported for this filesystem or OS version
/// then errors will be `ERROR_NOT_SUPPORTED` or `ERROR_INVALID_PARAMETER`.
#[allow(unused)]
fn posix_delete(&self) -> Result<(), WinError> {
let info = c::FILE_DISPOSITION_INFO_EX {
Flags: c::FILE_DISPOSITION_FLAG_DELETE
| c::FILE_DISPOSITION_FLAG_POSIX_SEMANTICS
| c::FILE_DISPOSITION_FLAG_IGNORE_READONLY_ATTRIBUTE,
};
api::set_file_information_by_handle(self.handle.as_raw_handle(), &info)
}
/// Delete a file using win32 semantics. The file won't actually be deleted
/// until all file handles are closed. However, marking a file for deletion
/// will prevent anyone from opening a new handle to the file.
#[allow(unused)]
fn win32_delete(&self) -> Result<(), WinError> {
let info = c::FILE_DISPOSITION_INFO { DeleteFile: c::TRUE as _ };
api::set_file_information_by_handle(self.handle.as_raw_handle(), &info)
}
/// Fill the given buffer with as many directory entries as will fit.
/// This will remember its position and continue from the last call unless
/// `restart` is set to `true`.
///
/// The returned bool indicates if there are more entries or not.
/// It is an error if `self` is not a directory.
///
/// # Symlinks and other reparse points
///
/// On Windows a file is either a directory or a non-directory.
/// A symlink directory is simply an empty directory with some "reparse" metadata attached.
/// So if you open a link (not its target) and iterate the directory,
/// you will always iterate an empty directory regardless of the target.
#[allow(unused)]
fn fill_dir_buff(&self, buffer: &mut DirBuff, restart: bool) -> Result<bool, WinError> {
let class =
if restart { c::FileIdBothDirectoryRestartInfo } else { c::FileIdBothDirectoryInfo };
unsafe {
let result = c::GetFileInformationByHandleEx(
self.as_raw_handle(),
class,
buffer.as_mut_ptr().cast(),
buffer.capacity() as _,
);
if result == 0 {
let err = api::get_last_error();
if err.code == c::ERROR_NO_MORE_FILES { Ok(false) } else { Err(err) }
} else {
Ok(true)
}
}
}
}
/// A buffer for holding directory entries.
struct DirBuff {
buffer: Box<Align8<[MaybeUninit<u8>; Self::BUFFER_SIZE]>>,
}
impl DirBuff {
const BUFFER_SIZE: usize = 1024;
fn new() -> Self {
Self {
// Safety: `Align8<[MaybeUninit<u8>; N]>` does not need
// initialization.
buffer: unsafe { Box::new_uninit().assume_init() },
}
}
fn capacity(&self) -> usize {
self.buffer.0.len()
}
fn as_mut_ptr(&mut self) -> *mut u8 {
self.buffer.0.as_mut_ptr().cast()
}
/// Returns a `DirBuffIter`.
fn iter(&self) -> DirBuffIter<'_> {
DirBuffIter::new(self)
}
}
impl AsRef<[MaybeUninit<u8>]> for DirBuff {
fn as_ref(&self) -> &[MaybeUninit<u8>] {
&self.buffer.0
}
}
/// An iterator over entries stored in a `DirBuff`.
///
/// Currently only returns file names (UTF-16 encoded).
struct DirBuffIter<'a> {
buffer: Option<&'a [MaybeUninit<u8>]>,
cursor: usize,
}
impl<'a> DirBuffIter<'a> {
fn new(buffer: &'a DirBuff) -> Self {
Self { buffer: Some(buffer.as_ref()), cursor: 0 }
}
}
impl<'a> Iterator for DirBuffIter<'a> {
type Item = (Cow<'a, [u16]>, bool);
fn next(&mut self) -> Option<Self::Item> {
use crate::mem::size_of;
let buffer = &self.buffer?[self.cursor..];
// Get the name and next entry from the buffer.
// SAFETY:
// - The buffer contains a `FILE_ID_BOTH_DIR_INFO` struct but the last
// field (the file name) is unsized. So an offset has to be used to
// get the file name slice.
// - The OS has guaranteed initialization of the fields of
// `FILE_ID_BOTH_DIR_INFO` and the trailing filename (for at least
// `FileNameLength` bytes)
let (name, is_directory, next_entry) = unsafe {
let info = buffer.as_ptr().cast::<c::FILE_ID_BOTH_DIR_INFO>();
// While this is guaranteed to be aligned in documentation for
// https://docs.microsoft.com/en-us/windows/win32/api/winbase/ns-winbase-file_id_both_dir_info
// it does not seem that reality is so kind, and assuming this
// caused crashes in some cases (https://github.com/rust-lang/rust/issues/104530)
// presumably, this can be blamed on buggy filesystem drivers, but who knows.
let next_entry = ptr::addr_of!((*info).NextEntryOffset).read_unaligned() as usize;
let length = ptr::addr_of!((*info).FileNameLength).read_unaligned() as usize;
let attrs = ptr::addr_of!((*info).FileAttributes).read_unaligned();
let name = from_maybe_unaligned(
ptr::addr_of!((*info).FileName).cast::<u16>(),
length / size_of::<u16>(),
);
let is_directory = (attrs & c::FILE_ATTRIBUTE_DIRECTORY) != 0;
(name, is_directory, next_entry)
};
if next_entry == 0 {
self.buffer = None
} else {
self.cursor += next_entry
}
// Skip `.` and `..` pseudo entries.
const DOT: u16 = b'.' as u16;
match &name[..] {
[DOT] | [DOT, DOT] => self.next(),
_ => Some((name, is_directory)),
}
}
}
unsafe fn from_maybe_unaligned<'a>(p: *const u16, len: usize) -> Cow<'a, [u16]> {
unsafe {
if p.is_aligned() {
Cow::Borrowed(crate::slice::from_raw_parts(p, len))
} else {
Cow::Owned((0..len).map(|i| p.add(i).read_unaligned()).collect())
}
}
}
impl AsInner<Handle> for File {
#[inline]
fn as_inner(&self) -> &Handle {
&self.handle
}
}
impl IntoInner<Handle> for File {
fn into_inner(self) -> Handle {
self.handle
}
}
impl FromInner<Handle> for File {
fn from_inner(handle: Handle) -> File {
File { handle }
}
}
impl AsHandle for File {
fn as_handle(&self) -> BorrowedHandle<'_> {
self.as_inner().as_handle()
}
}
impl AsRawHandle for File {
fn as_raw_handle(&self) -> RawHandle {
self.as_inner().as_raw_handle()
}
}
impl IntoRawHandle for File {
fn into_raw_handle(self) -> RawHandle {
self.into_inner().into_raw_handle()
}
}
impl FromRawHandle for File {
unsafe fn from_raw_handle(raw_handle: RawHandle) -> Self {
unsafe {
Self { handle: FromInner::from_inner(FromRawHandle::from_raw_handle(raw_handle)) }
}
}
}
impl fmt::Debug for File {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// FIXME(#24570): add more info here (e.g., mode)
let mut b = f.debug_struct("File");
b.field("handle", &self.handle.as_raw_handle());
if let Ok(path) = get_path(self) {
b.field("path", &path);
}
b.finish()
}
}
impl FileAttr {
pub fn size(&self) -> u64 {
self.file_size
}
pub fn perm(&self) -> FilePermissions {
FilePermissions { attrs: self.attributes }
}
pub fn attrs(&self) -> u32 {
self.attributes
}
pub fn file_type(&self) -> FileType {
FileType::new(self.attributes, self.reparse_tag)
}
pub fn modified(&self) -> io::Result<SystemTime> {
Ok(SystemTime::from(self.last_write_time))
}
pub fn accessed(&self) -> io::Result<SystemTime> {
Ok(SystemTime::from(self.last_access_time))
}
pub fn created(&self) -> io::Result<SystemTime> {
Ok(SystemTime::from(self.creation_time))
}
pub fn modified_u64(&self) -> u64 {
to_u64(&self.last_write_time)
}
pub fn accessed_u64(&self) -> u64 {
to_u64(&self.last_access_time)
}
pub fn created_u64(&self) -> u64 {
to_u64(&self.creation_time)
}
pub fn changed_u64(&self) -> Option<u64> {
self.change_time.as_ref().map(|c| to_u64(c))
}
pub fn volume_serial_number(&self) -> Option<u32> {
self.volume_serial_number
}
pub fn number_of_links(&self) -> Option<u32> {
self.number_of_links
}
pub fn file_index(&self) -> Option<u64> {
self.file_index
}
}
impl From<c::WIN32_FIND_DATAW> for FileAttr {
fn from(wfd: c::WIN32_FIND_DATAW) -> Self {
FileAttr {
attributes: wfd.dwFileAttributes,
creation_time: wfd.ftCreationTime,
last_access_time: wfd.ftLastAccessTime,
last_write_time: wfd.ftLastWriteTime,
change_time: None,
file_size: ((wfd.nFileSizeHigh as u64) << 32) | (wfd.nFileSizeLow as u64),
reparse_tag: if wfd.dwFileAttributes & c::FILE_ATTRIBUTE_REPARSE_POINT != 0 {
// reserved unless this is a reparse point
wfd.dwReserved0
} else {
0
},
volume_serial_number: None,
number_of_links: None,
file_index: None,
}
}
}
fn to_u64(ft: &c::FILETIME) -> u64 {
(ft.dwLowDateTime as u64) | ((ft.dwHighDateTime as u64) << 32)
}
impl FilePermissions {
pub fn readonly(&self) -> bool {
self.attrs & c::FILE_ATTRIBUTE_READONLY != 0
}
pub fn set_readonly(&mut self, readonly: bool) {
if readonly {
self.attrs |= c::FILE_ATTRIBUTE_READONLY;
} else {
self.attrs &= !c::FILE_ATTRIBUTE_READONLY;
}
}
}
impl FileTimes {
pub fn set_accessed(&mut self, t: SystemTime) {
self.accessed = Some(t.into_inner());
}
pub fn set_modified(&mut self, t: SystemTime) {
self.modified = Some(t.into_inner());
}
pub fn set_created(&mut self, t: SystemTime) {
self.created = Some(t.into_inner());
}
}
impl FileType {
fn new(attrs: u32, reparse_tag: u32) -> FileType {
FileType { attributes: attrs, reparse_tag }
}
pub fn is_dir(&self) -> bool {
!self.is_symlink() && self.is_directory()
}
pub fn is_file(&self) -> bool {
!self.is_symlink() && !self.is_directory()
}
pub fn is_symlink(&self) -> bool {
self.is_reparse_point() && self.is_reparse_tag_name_surrogate()
}
pub fn is_symlink_dir(&self) -> bool {
self.is_symlink() && self.is_directory()
}
pub fn is_symlink_file(&self) -> bool {
self.is_symlink() && !self.is_directory()
}
fn is_directory(&self) -> bool {
self.attributes & c::FILE_ATTRIBUTE_DIRECTORY != 0
}
fn is_reparse_point(&self) -> bool {
self.attributes & c::FILE_ATTRIBUTE_REPARSE_POINT != 0
}
fn is_reparse_tag_name_surrogate(&self) -> bool {
self.reparse_tag & 0x20000000 != 0
}
}
impl DirBuilder {
pub fn new() -> DirBuilder {
DirBuilder
}
pub fn mkdir(&self, p: &Path) -> io::Result<()> {
let p = maybe_verbatim(p)?;
cvt(unsafe { c::CreateDirectoryW(p.as_ptr(), ptr::null_mut()) })?;
Ok(())
}
}
pub fn readdir(p: &Path) -> io::Result<ReadDir> {
// We push a `*` to the end of the path which cause the empty path to be
// treated as the current directory. So, for consistency with other platforms,
// we explicitly error on the empty path.
if p.as_os_str().is_empty() {
// Return an error code consistent with other ways of opening files.
// E.g. fs::metadata or File::open.
return Err(io::Error::from_raw_os_error(c::ERROR_PATH_NOT_FOUND as i32));
}
let root = p.to_path_buf();
let star = p.join("*");
let path = maybe_verbatim(&star)?;
unsafe {
let mut wfd = mem::zeroed();
let find_handle = c::FindFirstFileW(path.as_ptr(), &mut wfd);
if find_handle != c::INVALID_HANDLE_VALUE {
Ok(ReadDir {
handle: FindNextFileHandle(find_handle),
root: Arc::new(root),
first: Some(wfd),
})
} else {
// The status `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function
// if no matching files can be found, but not necessarily that the path to find the
// files in does not exist.
//
// Hence, a check for whether the path to search in exists is added when the last
// os error returned by Windows is `ERROR_FILE_NOT_FOUND` to handle this scenario.
// If that is the case, an empty `ReadDir` iterator is returned as it returns `None`
// in the initial `.next()` invocation because `ERROR_NO_MORE_FILES` would have been
// returned by the `FindNextFileW` function.
//
// See issue #120040: https://github.com/rust-lang/rust/issues/120040.
let last_error = api::get_last_error();
if last_error == WinError::FILE_NOT_FOUND {
return Ok(ReadDir {
handle: FindNextFileHandle(find_handle),
root: Arc::new(root),
first: None,
});
}
// 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
// when the path to search in does not exist in the first place.
Err(Error::from_raw_os_error(last_error.code as i32))
}
}
}
pub fn unlink(p: &Path) -> io::Result<()> {
let p_u16s = maybe_verbatim(p)?;
cvt(unsafe { c::DeleteFileW(p_u16s.as_ptr()) })?;
Ok(())
}
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) })?;
Ok(())
}
pub fn rmdir(p: &Path) -> io::Result<()> {
let p = maybe_verbatim(p)?;
cvt(unsafe { c::RemoveDirectoryW(p.as_ptr()) })?;
Ok(())
}
pub fn remove_dir_all(path: &Path) -> io::Result<()> {
// Open a file or directory without following symlinks.
let mut opts = OpenOptions::new();
opts.access_mode(c::FILE_LIST_DIRECTORY);
// `FILE_FLAG_BACKUP_SEMANTICS` allows opening directories.
// `FILE_FLAG_OPEN_REPARSE_POINT` opens a link instead of its target.
opts.custom_flags(c::FILE_FLAG_BACKUP_SEMANTICS | c::FILE_FLAG_OPEN_REPARSE_POINT);
let file = File::open(path, &opts)?;
// Test if the file is not a directory or a symlink to a directory.
if (file.basic_info()?.FileAttributes & c::FILE_ATTRIBUTE_DIRECTORY) == 0 {
return Err(io::Error::from_raw_os_error(c::ERROR_DIRECTORY as _));
}
// Remove the directory and all its contents.
remove_dir_all_iterative(file).io_result()
}
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
// this is needed for a common case.
let mut opts = OpenOptions::new();
opts.access_mode(0);
opts.custom_flags(c::FILE_FLAG_OPEN_REPARSE_POINT | c::FILE_FLAG_BACKUP_SEMANTICS);
let file = File::open(path, &opts)?;
file.readlink()
}
pub fn symlink(original: &Path, link: &Path) -> io::Result<()> {
symlink_inner(original, link, false)
}
pub fn symlink_inner(original: &Path, link: &Path, dir: bool) -> io::Result<()> {
let original = to_u16s(original)?;
let link = maybe_verbatim(link)?;
let flags = if dir { c::SYMBOLIC_LINK_FLAG_DIRECTORY } else { 0 };
// Formerly, symlink creation required the SeCreateSymbolicLink privilege. For the Windows 10
// Creators Update, Microsoft loosened this to allow unprivileged symlink creation if the
// computer is in Developer Mode, but SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE must be
// added to dwFlags to opt into this behaviour.
let result = cvt(unsafe {
c::CreateSymbolicLinkW(
link.as_ptr(),
original.as_ptr(),
flags | c::SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE,
) as c::BOOL
});
if let Err(err) = result {
if err.raw_os_error() == Some(c::ERROR_INVALID_PARAMETER as i32) {
// Older Windows objects to SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE,
// so if we encounter ERROR_INVALID_PARAMETER, retry without that flag.
cvt(unsafe {
c::CreateSymbolicLinkW(link.as_ptr(), original.as_ptr(), flags) as c::BOOL
})?;
} else {
return Err(err);
}
}
Ok(())
}
#[cfg(not(target_vendor = "uwp"))]
pub fn link(original: &Path, link: &Path) -> io::Result<()> {
let original = maybe_verbatim(original)?;
let link = maybe_verbatim(link)?;
cvt(unsafe { c::CreateHardLinkW(link.as_ptr(), original.as_ptr(), ptr::null_mut()) })?;
Ok(())
}
#[cfg(target_vendor = "uwp")]
pub fn link(_original: &Path, _link: &Path) -> io::Result<()> {
return Err(io::const_io_error!(
io::ErrorKind::Unsupported,
"hard link are not supported on UWP",
));
}
pub fn stat(path: &Path) -> io::Result<FileAttr> {
match metadata(path, ReparsePoint::Follow) {
Err(err) if err.raw_os_error() == Some(c::ERROR_CANT_ACCESS_FILE as i32) => {
if let Ok(attrs) = lstat(path) {
if !attrs.file_type().is_symlink() {
return Ok(attrs);
}
}
Err(err)
}
result => result,
}
}
pub fn lstat(path: &Path) -> io::Result<FileAttr> {
metadata(path, ReparsePoint::Open)
}
#[repr(u32)]
#[derive(Clone, Copy, PartialEq, Eq)]
enum ReparsePoint {
Follow = 0,
Open = c::FILE_FLAG_OPEN_REPARSE_POINT,
}
impl ReparsePoint {
fn as_flag(self) -> u32 {
self as u32
}
}
fn metadata(path: &Path, reparse: ReparsePoint) -> io::Result<FileAttr> {
let mut opts = OpenOptions::new();
// No read or write permissions are necessary
opts.access_mode(0);
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 the fallback fails for any reason we return the original error.
match File::open(path, &opts) {
Ok(file) => file.file_attr(),
Err(e)
if [Some(c::ERROR_SHARING_VIOLATION as _), Some(c::ERROR_ACCESS_DENIED as _)]
.contains(&e.raw_os_error()) =>
{
// `ERROR_ACCESS_DENIED` is returned when the user doesn't have permission for the resource.
// One such example is `System Volume Information` as default but can be created as well
// `ERROR_SHARING_VIOLATION` will almost never be returned.
// Usually if a file is locked you can still read some metadata.
// However, there are special system files, such as
// `C:\hiberfil.sys`, that are locked in a way that denies even that.
unsafe {
let path = maybe_verbatim(path)?;
// `FindFirstFileW` 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);
if handle == c::INVALID_HANDLE_VALUE {
// This can fail if the user does not have read access to the
// directory.
Err(e)
} else {
// We no longer need the find handle.
c::FindClose(handle);
// `FindFirstFileW` 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() {
Err(e)
} else {
Ok(attrs)
}
}
}
}
Err(e) => Err(e),
}
}
pub fn set_perm(p: &Path, perm: FilePermissions) -> io::Result<()> {
let p = maybe_verbatim(p)?;
unsafe {
cvt(c::SetFileAttributesW(p.as_ptr(), perm.attrs))?;
Ok(())
}
}
fn get_path(f: &File) -> io::Result<PathBuf> {
super::fill_utf16_buf(
|buf, sz| unsafe {
c::GetFinalPathNameByHandleW(f.handle.as_raw_handle(), buf, sz, c::VOLUME_NAME_DOS)
},
|buf| PathBuf::from(OsString::from_wide(buf)),
)
}
pub fn canonicalize(p: &Path) -> io::Result<PathBuf> {
let mut opts = OpenOptions::new();
// No read or write permissions are necessary
opts.access_mode(0);
// This flag is so we can open directories too
opts.custom_flags(c::FILE_FLAG_BACKUP_SEMANTICS);
let f = File::open(p, &opts)?;
get_path(&f)
}
pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
unsafe extern "system" fn callback(
_TotalFileSize: i64,
_TotalBytesTransferred: i64,
_StreamSize: i64,
StreamBytesTransferred: i64,
dwStreamNumber: u32,
_dwCallbackReason: u32,
_hSourceFile: c::HANDLE,
_hDestinationFile: c::HANDLE,
lpData: *const c_void,
) -> u32 {
unsafe {
if dwStreamNumber == 1 {
*(lpData as *mut i64) = StreamBytesTransferred;
}
c::PROGRESS_CONTINUE
}
}
let pfrom = maybe_verbatim(from)?;
let pto = maybe_verbatim(to)?;
let mut size = 0i64;
cvt(unsafe {
c::CopyFileExW(
pfrom.as_ptr(),
pto.as_ptr(),
Some(callback),
core::ptr::addr_of_mut!(size) as *mut _,
ptr::null_mut(),
0,
)
})?;
Ok(size as u64)
}
pub fn junction_point(original: &Path, link: &Path) -> io::Result<()> {
// Create and open a new directory in one go.
let mut opts = OpenOptions::new();
opts.create_new(true);
opts.write(true);
opts.custom_flags(c::FILE_FLAG_BACKUP_SEMANTICS | c::FILE_FLAG_POSIX_SEMANTICS);
opts.attributes(c::FILE_ATTRIBUTE_DIRECTORY);
let d = File::open(link, &opts)?;
// We need to get an absolute, NT-style path.
let path_bytes = original.as_os_str().as_encoded_bytes();
let abs_path: Vec<u16> = if path_bytes.starts_with(br"\\?\") || path_bytes.starts_with(br"\??\")
{
// It's already an absolute path, we just need to convert the prefix to `\??\`
let bytes = unsafe { OsStr::from_encoded_bytes_unchecked(&path_bytes[4..]) };
r"\??\".encode_utf16().chain(bytes.encode_wide()).collect()
} else {
// Get an absolute path and then convert the prefix to `\??\`
let abs_path = crate::path::absolute(original)?.into_os_string().into_encoded_bytes();
if abs_path.len() > 0 && abs_path[1..].starts_with(br":\") {
let bytes = unsafe { OsStr::from_encoded_bytes_unchecked(&abs_path) };
r"\??\".encode_utf16().chain(bytes.encode_wide()).collect()
} else if abs_path.starts_with(br"\\.\") {
let bytes = unsafe { OsStr::from_encoded_bytes_unchecked(&abs_path[4..]) };
r"\??\".encode_utf16().chain(bytes.encode_wide()).collect()
} else if abs_path.starts_with(br"\\") {
let bytes = unsafe { OsStr::from_encoded_bytes_unchecked(&abs_path[2..]) };
r"\??\UNC\".encode_utf16().chain(bytes.encode_wide()).collect()
} else {
return Err(io::const_io_error!(io::ErrorKind::InvalidInput, "path is not valid"));
}
};
// Defined inline so we don't have to mess about with variable length buffer.
#[repr(C)]
pub struct MountPointBuffer {
ReparseTag: u32,
ReparseDataLength: u16,
Reserved: u16,
SubstituteNameOffset: u16,
SubstituteNameLength: u16,
PrintNameOffset: u16,
PrintNameLength: u16,
PathBuffer: [MaybeUninit<u16>; c::MAXIMUM_REPARSE_DATA_BUFFER_SIZE as usize],
}
let data_len = 12 + (abs_path.len() * 2);
if data_len > u16::MAX as usize {
return Err(io::const_io_error!(
io::ErrorKind::InvalidInput,
"`original` path is too long"
));
}
let data_len = data_len as u16;
let mut header = MountPointBuffer {
ReparseTag: c::IO_REPARSE_TAG_MOUNT_POINT,
ReparseDataLength: data_len,
Reserved: 0,
SubstituteNameOffset: 0,
SubstituteNameLength: (abs_path.len() * 2) as u16,
PrintNameOffset: ((abs_path.len() + 1) * 2) as u16,
PrintNameLength: 0,
PathBuffer: [MaybeUninit::uninit(); c::MAXIMUM_REPARSE_DATA_BUFFER_SIZE as usize],
};
unsafe {
let ptr = header.PathBuffer.as_mut_ptr();
ptr.copy_from(abs_path.as_ptr().cast::<MaybeUninit<u16>>(), abs_path.len());
let mut ret = 0;
cvt(c::DeviceIoControl(
d.as_raw_handle(),
c::FSCTL_SET_REPARSE_POINT,
addr_of!(header).cast::<c_void>(),
data_len as u32 + 8,
ptr::null_mut(),
0,
&mut ret,
ptr::null_mut(),
))
.map(drop)
}
}
// Try to see if a file exists but, unlike `exists`, report I/O errors.
pub fn exists(path: &Path) -> io::Result<bool> {
// Open the file to ensure any symlinks are followed to their target.
let mut opts = OpenOptions::new();
// No read, write, etc access rights are needed.
opts.access_mode(0);
// Backup semantics enables opening directories as well as files.
opts.custom_flags(c::FILE_FLAG_BACKUP_SEMANTICS);
match File::open(path, &opts) {
Err(e) => match e.kind() {
// The file definitely does not exist
io::ErrorKind::NotFound => Ok(false),
// `ERROR_SHARING_VIOLATION` means that the file has been locked by
// another process. This is often temporary so we simply report it
// as the file existing.
_ if e.raw_os_error() == Some(c::ERROR_SHARING_VIOLATION as i32) => Ok(true),
// `ERROR_CANT_ACCESS_FILE` means that a file exists but that the
// reparse point could not be handled by `CreateFile`.
// This can happen for special files such as:
// * Unix domain sockets which you need to `connect` to
// * App exec links which require using `CreateProcess`
_ if e.raw_os_error() == Some(c::ERROR_CANT_ACCESS_FILE as i32) => Ok(true),
// Other errors such as `ERROR_ACCESS_DENIED` may indicate that the
// file exists. However, these types of errors are usually more
// permanent so we report them here.
_ => Err(e),
},
// The file was opened successfully therefore it must exist,
Ok(_) => Ok(true),
}
}