Add fallback impl for File::truncate and File::seek

- Fallback for `SetFilePointerEx` based on `SetFilePointer`
- Fallback for `SetFileInformationByHandle` with `FileEndOfFileInfo`
  based on `SetFilePointerEx` and `SetEndOfFile`

Signed-off-by: Dennis Duda <git@seri.tools>

Author: seritools

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

@@ -213,6 +213,8 @@ pub struct SYSTEMTIME {
 
 pub type LPSYSTEMTIME = *mut SYSTEMTIME;
 
+pub const INVALID_SET_FILE_POINTER: WIN32_ERROR = 0xFFFFFFFFu32;
+
 pub unsafe extern "system" fn WriteFileEx(
     hFile: BorrowedHandle<'_>,
     lpBuffer: *mut ::core::ffi::c_void,
@@ -430,6 +432,44 @@ compat_fn_with_fallback! {
         GetSystemTime(&mut st);
         crate::sys::cvt(SystemTimeToFileTime(&st, lpSystemTimeAsFileTime)).unwrap();
     }
+
+    // >= 2000
+    // https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-setfilepointerex
+    pub fn SetFilePointerEx(
+        hFile: HANDLE,
+        liDistanceToMove: LARGE_INTEGER,
+        lpNewFilePointer: PLARGE_INTEGER,
+        dwMoveMethod: DWORD
+    ) -> BOOL {
+        let lDistanceToMove = liDistanceToMove as LONG;
+        let mut distance_to_move_high = (liDistanceToMove >> 32) as LONG;
+
+        let newPos_low = SetFilePointer(hFile, lDistanceToMove, &mut distance_to_move_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 newPos_low == INVALID_SET_FILE_POINTER && GetLastError() != NO_ERROR {
+            return FALSE;
+        }
+
+        if !lpNewFilePointer.is_null() {
+            *lpNewFilePointer = (distance_to_move_high as LARGE_INTEGER) << 32 | (newPos_low as LARGE_INTEGER);
+        }
+
+        TRUE
+    }
+
+    // >= Vista / Server 2008 (XP / Server 2003 when linking a supported FileExtd.lib)
+    // https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-setfileinformationbyhandle
+    pub fn SetFileInformationByHandle(
+        hFile: HANDLE,
+        FileInformationClass: FILE_INFO_BY_HANDLE_CLASS,
+        lpFileInformation: LPVOID,
+        dwBufferSize: DWORD
+    ) -> BOOL {
+        SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD);
+        FALSE
+    }
 }
 
 compat_fn_optional! {
@@ -495,4 +535,13 @@ extern "system" {
 
     pub fn GetSystemTime(lpSystemTime: LPSYSTEMTIME);
     pub fn SystemTimeToFileTime(lpSystemTime: *const SYSTEMTIME, lpFileTime: LPFILETIME) -> BOOL;
+
+    pub fn SetEndOfFile(hFile: HANDLE) -> BOOL;
+
+    pub fn SetFilePointer(
+        hFile: HANDLE,
+        lDistanceToMove: LONG,
+        lpDistanceToMoveHigh: *mut LONG,
+        dwMoveMethod: DWORD,
+    ) -> DWORD;
 }

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

@@ -2372,8 +2372,6 @@ 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.SetFileAttributesW
-Windows.Win32.Storage.FileSystem.SetFileInformationByHandle
-Windows.Win32.Storage.FileSystem.SetFilePointerEx
 Windows.Win32.Storage.FileSystem.SetFileTime
 Windows.Win32.Storage.FileSystem.SPECIFIC_RIGHTS_ALL
 Windows.Win32.Storage.FileSystem.STANDARD_RIGHTS_ALL

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

@@ -435,24 +435,6 @@ extern "system" {
     ) -> BOOL;
 }
 #[link(name = "kernel32")]
-extern "system" {
-    pub fn SetFileInformationByHandle(
-        hfile: HANDLE,
-        fileinformationclass: FILE_INFO_BY_HANDLE_CLASS,
-        lpfileinformation: *const ::core::ffi::c_void,
-        dwbuffersize: u32,
-    ) -> BOOL;
-}
-#[link(name = "kernel32")]
-extern "system" {
-    pub fn SetFilePointerEx(
-        hfile: HANDLE,
-        lidistancetomove: i64,
-        lpnewfilepointer: *mut i64,
-        dwmovemethod: SET_FILE_POINTER_MOVE_METHOD,
-    ) -> BOOL;
-}
-#[link(name = "kernel32")]
 extern "system" {
     pub fn SetFileTime(
         hfile: HANDLE,

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

@@ -316,16 +316,50 @@ impl File {
     }
 
     pub fn truncate(&self, size: u64) -> io::Result<()> {
-        let mut info = c::FILE_END_OF_FILE_INFO { EndOfFile: size as c::LARGE_INTEGER };
-        let size = mem::size_of_val(&info);
-        cvt(unsafe {
-            c::SetFileInformationByHandle(
-                self.handle.as_raw_handle(),
-                c::FileEndOfFileInfo,
-                &mut info as *mut _ as *mut _,
-                size as c::DWORD,
-            )
-        })?;
+        if c::SetFileInformationByHandle::available() {
+            let mut info = c::FILE_END_OF_FILE_INFO { EndOfFile: size as c::LARGE_INTEGER };
+            let size = mem::size_of_val(&info);
+
+            cvt(unsafe {
+                c::SetFileInformationByHandle(
+                    self.handle.as_raw_handle(),
+                    c::FileEndOfFileInfo,
+                    &mut info as *mut _ as *mut _,
+                    size as c::DWORD,
+                )
+            })?;
+        } else {
+            let mut saved_pos = 0;
+            unsafe {
+                // get current file pointer position
+                cvt(c::SetFilePointerEx(
+                    self.handle.as_raw_handle(),
+                    0,
+                    &mut saved_pos,
+                    c::FILE_CURRENT,
+                ))?;
+
+                // seek to new end position
+                cvt(c::SetFilePointerEx(
+                    self.handle.as_raw_handle(),
+                    size as c::LARGE_INTEGER,
+                    ptr::null_mut(),
+                    c::FILE_BEGIN,
+                ))?;
+
+                // set current position as end of file
+                cvt(c::SetEndOfFile(self.handle.as_raw_handle()))?;
+
+                // go back to saved position
+                cvt(c::SetFilePointerEx(
+                    self.handle.as_raw_handle(),
+                    saved_pos as c::LARGE_INTEGER,
+                    ptr::null_mut(),
+                    c::FILE_BEGIN,
+                ))?;
+            }
+        }
+
         Ok(())
     }