Add fallback impls for File::truncate and File::seek, file_attr

- Fallback for `SetFilePointerEx` based on `SetFilePointer`
- Fallback for file truncation (`SetFileInformationByHandle` with `FileEndOfFileInfo`)
  based on `SetFilePointerEx` and `SetEndOfFile`
- file_attr: Don't query reparse tag if API is not available (`GetFileInformationByHandleEx` with `FileAttributeTagInfo`)

Author: seritools

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

@@ -390,3 +390,58 @@ compat_fn_with_fallback! {
         rtabort!("unimplemented")
     }
 }
+
+#[cfg(target_vendor = "rust9x")]
+compat_fn_with_fallback! {
+    pub static KERNEL32: &CStr = c"kernel32" => { load: false, unicows: false };
+    // >= 2000
+    // https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-setfilepointerex
+    pub fn SetFilePointerEx(
+        hfile: HANDLE,
+        lidistancetomove: i64,
+        lpnewfilepointer: *mut i64,
+        dwmovemethod: SET_FILE_POINTER_MOVE_METHOD,
+    ) -> BOOL {
+        unsafe {
+            let distance_low = lidistancetomove as i32;
+            let mut distance_high = (lidistancetomove >> 32) as i32;
+
+            let new_pos_low = SetFilePointer(hfile, distance_low, &mut distance_high, dwmovemethod);
+
+            // since (-1 as u32) could be a valid value for the lower 32 bits of the new file
+            // pointer position, a call to GetLastError is needed to actually see if it failed
+            if new_pos_low == INVALID_SET_FILE_POINTER && GetLastError() != NO_ERROR {
+                return FALSE;
+            }
+
+            if !lpnewfilepointer.is_null() {
+                *lpnewfilepointer = (distance_high as i64) << 32 | (new_pos_low as i64);
+            }
+
+            TRUE
+        }
+    }
+
+    // >= Vista / Server 2008 (XP / Server 2003 when linking a supported FileExtd.lib)
+    // https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-setfileinformationbyhandle
+    pub fn SetFileInformationByHandle(
+        hfile: HANDLE,
+        fileinformationclass: FILE_INFO_BY_HANDLE_CLASS,
+        lpfileinformation: *const ::core::ffi::c_void,
+        dwbuffersize: u32,
+    ) -> BOOL {
+        unsafe { SetLastError(ERROR_CALL_NOT_IMPLEMENTED as u32); };
+        FALSE
+    }
+    // >= Vista / Server 2008 (XP / Server 2003 when linking a supported FileExtd.lib)
+    // https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getfileinformationbyhandleex
+    pub fn GetFileInformationByHandleEx(
+        hfile: HANDLE,
+        fileinformationclass: FILE_INFO_BY_HANDLE_CLASS,
+        lpfileinformation: *mut ::core::ffi::c_void,
+        dwbuffersize: u32,
+    ) -> BOOL {
+        unsafe { SetLastError(ERROR_CALL_NOT_IMPLEMENTED as u32); };
+        FALSE
+    }
+}

library/std/src/sys/pal/windows/c/bindings.txt

@@ -2352,6 +2352,7 @@ Windows.Win32.Storage.FileSystem.GetFinalPathNameByHandleW
 Windows.Win32.Storage.FileSystem.GetFullPathNameW
 Windows.Win32.Storage.FileSystem.GetTempPathW
 Windows.Win32.Storage.FileSystem.INVALID_FILE_ATTRIBUTES
+Windows.Win32.Storage.FileSystem.INVALID_SET_FILE_POINTER
 Windows.Win32.Storage.FileSystem.LOCKFILE_EXCLUSIVE_LOCK
 Windows.Win32.Storage.FileSystem.LOCKFILE_FAIL_IMMEDIATELY
 Windows.Win32.Storage.FileSystem.LockFileEx
@@ -2385,8 +2386,10 @@ Windows.Win32.Storage.FileSystem.SECURITY_IMPERSONATION
 Windows.Win32.Storage.FileSystem.SECURITY_SQOS_PRESENT
 Windows.Win32.Storage.FileSystem.SECURITY_VALID_SQOS_FLAGS
 Windows.Win32.Storage.FileSystem.SET_FILE_POINTER_MOVE_METHOD
+Windows.Win32.Storage.FileSystem.SetEndOfFile
 Windows.Win32.Storage.FileSystem.SetFileAttributesW
 Windows.Win32.Storage.FileSystem.SetFileInformationByHandle
+Windows.Win32.Storage.FileSystem.SetFilePointer
 Windows.Win32.Storage.FileSystem.SetFilePointerEx
 Windows.Win32.Storage.FileSystem.SetFileTime
 Windows.Win32.Storage.FileSystem.SPECIFIC_RIGHTS_ALL

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

@@ -89,10 +89,12 @@ windows_targets::link!("kernel32.dll" "system" fn ReleaseSRWLockShared(srwlock :
 windows_targets::link!("kernel32.dll" "system" fn RemoveDirectoryW(lppathname : PCWSTR) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn ResetEvent(hevent : HANDLE) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn SetCurrentDirectoryW(lppathname : PCWSTR) -> BOOL);
+windows_targets::link!("kernel32.dll" "system" fn SetEndOfFile(hfile : HANDLE) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn SetEnvironmentVariableW(lpname : PCWSTR, lpvalue : PCWSTR) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn SetEvent(hevent : HANDLE) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn SetFileAttributesW(lpfilename : PCWSTR, dwfileattributes : FILE_FLAGS_AND_ATTRIBUTES) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn SetFileInformationByHandle(hfile : HANDLE, fileinformationclass : FILE_INFO_BY_HANDLE_CLASS, lpfileinformation : *const core::ffi::c_void, dwbuffersize : u32) -> BOOL);
+windows_targets::link!("kernel32.dll" "system" fn SetFilePointer(hfile : HANDLE, ldistancetomove : i32, lpdistancetomovehigh : *mut i32, dwmovemethod : SET_FILE_POINTER_MOVE_METHOD) -> u32);
 windows_targets::link!("kernel32.dll" "system" fn SetFilePointerEx(hfile : HANDLE, lidistancetomove : i64, lpnewfilepointer : *mut i64, dwmovemethod : SET_FILE_POINTER_MOVE_METHOD) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn SetFileTime(hfile : HANDLE, lpcreationtime : *const FILETIME, lplastaccesstime : *const FILETIME, lplastwritetime : *const FILETIME) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn SetHandleInformation(hobject : HANDLE, dwmask : u32, dwflags : HANDLE_FLAGS) -> BOOL);
@@ -2681,6 +2683,7 @@ pub union INIT_ONCE {
 }
 pub const INIT_ONCE_INIT_FAILED: u32 = 4u32;
 pub const INVALID_FILE_ATTRIBUTES: u32 = 4294967295u32;
+pub const INVALID_SET_FILE_POINTER: u32 = 4294967295u32;
 pub const INVALID_SOCKET: SOCKET = -1i32 as _;
 #[repr(C)]
 #[derive(Clone, Copy)]

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

@@ -328,16 +328,7 @@ impl File {
                         mem::size_of::<c::FILE_ALLOCATION_INFO>() as u32,
                     );
                     if result == 0 {
-                        let eof = c::FILE_END_OF_FILE_INFO { EndOfFile: 0 };
-                        let result = c::SetFileInformationByHandle(
-                            handle.as_raw_handle(),
-                            c::FileEndOfFileInfo,
-                            (&raw const 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());
-                        }
+                        Self::truncate_inner(handle.as_raw_handle(), 0)?
                     }
                 }
             }
@@ -471,8 +462,37 @@ impl File {
     }
 
     pub fn truncate(&self, size: u64) -> io::Result<()> {
+        Self::truncate_inner(self.handle.as_raw_handle(), size)
+    }
+
+    #[cfg(not(target_vendor = "rust9x"))]
+    pub fn truncate_inner(handle: RawHandle, 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()
+        api::set_file_information_by_handle(handle, &info).io_result()
+    }
+
+    #[cfg(target_vendor = "rust9x")]
+    pub fn truncate_inner(handle: RawHandle, size: u64) -> io::Result<()> {
+        if c::SetFileInformationByHandle::available().is_some() {
+            let info = c::FILE_END_OF_FILE_INFO { EndOfFile: size as i64 };
+            api::set_file_information_by_handle(handle, &info).io_result()
+        } else {
+            let mut saved_pos = 0i64;
+            unsafe {
+                // get current file pointer position
+                cvt(c::SetFilePointerEx(handle, 0, &mut saved_pos, c::FILE_CURRENT))?;
+
+                // seek to new end position
+                cvt(c::SetFilePointerEx(handle, size as i64, ptr::null_mut(), c::FILE_BEGIN))?;
+
+                // set current position as end of file
+                cvt(c::SetEndOfFile(handle))?;
+
+                // go back to saved position
+                cvt(c::SetFilePointerEx(handle, saved_pos, ptr::null_mut(), c::FILE_BEGIN))?;
+            }
+            Ok(())
+        }
     }
 
     #[cfg(not(target_vendor = "uwp"))]
@@ -482,15 +502,22 @@ impl File {
             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,
-                    (&raw 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;
+                #[cfg(target_vendor = "rust9x")]
+                let f = c::GetFileInformationByHandleEx::available();
+                #[cfg(not(target_vendor = "rust9x"))]
+                let f = Some(c::GetFileInformationByHandleEx);
+
+                if let Some(f) = f {
+                    let mut attr_tag: c::FILE_ATTRIBUTE_TAG_INFO = mem::zeroed();
+                    cvt(f(
+                        self.handle.as_raw_handle(),
+                        c::FileAttributeTagInfo,
+                        (&raw 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 {

library/std/src/sys/pal/windows/io.rs

@@ -124,7 +124,11 @@ fn msys_tty_on(handle: BorrowedHandle<'_>) -> bool {
     let mut name_info = FILE_NAME_INFO { FileNameLength: 0, FileName: [0; c::MAX_PATH as usize] };
     // Safety: buffer length is fixed.
     let res = unsafe {
-        c::GetFileInformationByHandleEx(
+        #[cfg(target_vendor = "rust9x")]
+        let Some(fun) = c::GetFileInformationByHandleEx::available() else { return false };
+        #[cfg(not(target_vendor = "rust9x"))]
+        let fun = c::GetFileInformationByHandleEx;
+        fun(
             handle.as_raw_handle(),
             c::FileNameInfo,
             (&raw mut name_info) as *mut c_void,