From cce566b6bd6e676b917bf0e914a86680a6f268c4 Mon Sep 17 00:00:00 2001
From: Jookia <contact@jookia.org>
Date: Wed, 1 Jul 2026 22:01:59 +1000
Subject: [PATCH] Implement GetFileSizeEx compatibility wrapper

Windows before 2000 lacks GetFileSizeEx which Rust relies on.
Implement a compatibility function that uses GetFileSize as a backup.
---
 library/std/src/sys/pal/windows/c.rs          | 24 +++++++++++++++++++
 .../std/src/sys/pal/windows/c/bindings.txt    |  2 ++
 .../std/src/sys/pal/windows/c/windows_sys.rs  |  2 ++
 3 files changed, 28 insertions(+)

diff --git a/library/std/src/sys/pal/windows/c.rs b/library/std/src/sys/pal/windows/c.rs
index 5f2557804be22..c9074bb780db7 100644
--- a/library/std/src/sys/pal/windows/c.rs
+++ b/library/std/src/sys/pal/windows/c.rs
@@ -800,3 +800,27 @@ compat_fn_with_fallback! {
         rtabort!("unimplemented")
     }
 }
+
+#[cfg(target_family = "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-getfilesizeex
+    pub fn GetFileSizeEx(
+        hfile: HANDLE,
+        lpfilesize: *mut i64
+    ) -> BOOL {
+        if lpfilesize.is_null() {
+            unsafe { SetLastError(ERROR_INVALID_PARAMETER as u32) };
+            return FALSE;
+        }
+        let mut high32 = 0;
+        let low32 = unsafe { GetFileSize(hfile, &mut high32) };
+        let full_size: u64 = ((high32 as u64) << 32) | (low32 as u64);
+        if low32 == INVALID_FILE_SIZE && unsafe { GetLastError() } != NO_ERROR {
+            FALSE
+        } else {
+            TRUE
+        }
+    }
+}
diff --git a/library/std/src/sys/pal/windows/c/bindings.txt b/library/std/src/sys/pal/windows/c/bindings.txt
index d48b2a627ac02..7ba816b7f86b8 100644
--- a/library/std/src/sys/pal/windows/c/bindings.txt
+++ b/library/std/src/sys/pal/windows/c/bindings.txt
@@ -2184,6 +2184,7 @@ GetExitCodeProcess
 GetFileAttributesW
 GetFileInformationByHandle
 GetFileInformationByHandleEx
+GetFileSize
 GetFileSizeEx
 GetFileType
 GETFINALPATHNAMEBYHANDLE_FLAGS
@@ -2234,6 +2235,7 @@ InitializeProcThreadAttributeList
 InitOnceBeginInitialize
 InitOnceComplete
 INVALID_FILE_ATTRIBUTES
+INVALID_FILE_SIZE
 INVALID_SET_FILE_POINTER
 INVALID_SOCKET
 IO_REPARSE_TAG_MOUNT_POINT
diff --git a/library/std/src/sys/pal/windows/c/windows_sys.rs b/library/std/src/sys/pal/windows/c/windows_sys.rs
index d431043b29521..a3caf3cc69ff9 100644
--- a/library/std/src/sys/pal/windows/c/windows_sys.rs
+++ b/library/std/src/sys/pal/windows/c/windows_sys.rs
@@ -53,6 +53,7 @@ windows_link::link!("kernel32.dll" "system" fn GetExitCodeProcess(hprocess : HAN
 windows_link::link!("kernel32.dll" "system" fn GetFileAttributesW(lpfilename : PCWSTR) -> u32);
 windows_link::link!("kernel32.dll" "system" fn GetFileInformationByHandle(hfile : HANDLE, lpfileinformation : *mut BY_HANDLE_FILE_INFORMATION) -> BOOL);
 windows_link::link!("kernel32.dll" "system" fn GetFileInformationByHandleEx(hfile : HANDLE, fileinformationclass : FILE_INFO_BY_HANDLE_CLASS, lpfileinformation : *mut core::ffi::c_void, dwbuffersize : u32) -> BOOL);
+windows_link::link!("kernel32.dll" "system" fn GetFileSize(hfile : HANDLE, lpfilesize : *mut u64) -> u32);
 windows_link::link!("kernel32.dll" "system" fn GetFileSizeEx(hfile : HANDLE, lpfilesize : *mut i64) -> BOOL);
 windows_link::link!("kernel32.dll" "system" fn GetFileType(hfile : HANDLE) -> FILE_TYPE);
 windows_link::link!("kernel32.dll" "system" fn GetFinalPathNameByHandleW(hfile : HANDLE, lpszfilepath : PWSTR, cchfilepath : u32, dwflags : GETFINALPATHNAMEBYHANDLE_FLAGS) -> u32);
@@ -2898,6 +2899,7 @@ impl Default for INIT_ONCE {
 }
 pub const INIT_ONCE_INIT_FAILED: u32 = 4u32;
 pub const INVALID_FILE_ATTRIBUTES: u32 = 4294967295u32;
+pub const INVALID_FILE_SIZE: u32 = 4294967295u32;
 pub const INVALID_SET_FILE_POINTER: u32 = 4294967295u32;
 pub const INVALID_SOCKET: SOCKET = -1i32 as _;
 #[repr(C)]