From cef23cbc46446136bedfa9817cf7a3395c276deb Mon Sep 17 00:00:00 2001
From: Christopher Berner <me@cberner.com>
Date: Fri, 27 Sep 2024 20:11:24 -0700
Subject: [PATCH] WIP: Windows

---
 .../std/src/sys/pal/windows/c/windows_sys.rs  |  2 +
 library/std/src/sys/pal/windows/fs.rs         | 62 +++++++++++++++++--
 2 files changed, 59 insertions(+), 5 deletions(-)

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 ab5f8919d7af6..4cfa747983666 100644
--- a/library/std/src/sys/pal/windows/c/windows_sys.rs
+++ b/library/std/src/sys/pal/windows/c/windows_sys.rs
@@ -65,6 +65,7 @@ windows_targets::link!("kernel32.dll" "system" fn InitOnceBeginInitialize(lpinit
 windows_targets::link!("kernel32.dll" "system" fn InitOnceComplete(lpinitonce : *mut INIT_ONCE, dwflags : u32, lpcontext : *const core::ffi::c_void) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn InitializeProcThreadAttributeList(lpattributelist : LPPROC_THREAD_ATTRIBUTE_LIST, dwattributecount : u32, dwflags : u32, lpsize : *mut usize) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn LocalFree(hmem : HLOCAL) -> HLOCAL);
+windows_targets::link!("kernel32.dll" "system" fn LockFileEx(hfile : HANDLE, dwflags : u32, dwreserved : u32, nnumberofbytestolocklow : u32, nnumberofbytestolockhigh : u32, lpoverlapped : *mut OVERLAPPED) -> bool);
 windows_targets::link!("kernel32.dll" "system" fn MoveFileExW(lpexistingfilename : PCWSTR, lpnewfilename : PCWSTR, dwflags : MOVE_FILE_FLAGS) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn MultiByteToWideChar(codepage : u32, dwflags : MULTI_BYTE_TO_WIDE_CHAR_FLAGS, lpmultibytestr : PCSTR, cbmultibyte : i32, lpwidecharstr : PWSTR, cchwidechar : i32) -> i32);
 windows_targets::link!("kernel32.dll" "system" fn QueryPerformanceCounter(lpperformancecount : *mut i64) -> BOOL);
@@ -96,6 +97,7 @@ windows_targets::link!("kernel32.dll" "system" fn TlsGetValue(dwtlsindex : u32)
 windows_targets::link!("kernel32.dll" "system" fn TlsSetValue(dwtlsindex : u32, lptlsvalue : *const core::ffi::c_void) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn TryAcquireSRWLockExclusive(srwlock : *mut SRWLOCK) -> BOOLEAN);
 windows_targets::link!("kernel32.dll" "system" fn TryAcquireSRWLockShared(srwlock : *mut SRWLOCK) -> BOOLEAN);
+windows_targets::link!("kernel32.dll" "system" fn UnlockFile(hfile : HANDLE, dwfileoffsetlow: u32, dwfileoffsethigh : u32, nnumberofbytestolocklow : u32, nnumberofbytestolockhigh : u32) -> bool);
 windows_targets::link!("kernel32.dll" "system" fn UpdateProcThreadAttribute(lpattributelist : LPPROC_THREAD_ATTRIBUTE_LIST, dwflags : u32, attribute : usize, lpvalue : *const core::ffi::c_void, cbsize : usize, lppreviousvalue : *mut core::ffi::c_void, lpreturnsize : *const usize) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn WaitForMultipleObjects(ncount : u32, lphandles : *const HANDLE, bwaitall : BOOL, dwmilliseconds : u32) -> WAIT_EVENT);
 windows_targets::link!("kernel32.dll" "system" fn WaitForSingleObject(hhandle : HANDLE, dwmilliseconds : u32) -> WAIT_EVENT);
diff --git a/library/std/src/sys/pal/windows/fs.rs b/library/std/src/sys/pal/windows/fs.rs
index 2e41071ada005..3633ad6c3fbd2 100644
--- a/library/std/src/sys/pal/windows/fs.rs
+++ b/library/std/src/sys/pal/windows/fs.rs
@@ -349,23 +349,75 @@ impl File {
     }
 
     pub fn lock(&self) -> io::Result<()> {
-        unsupported()
+        cvt(unsafe {
+            let overlapped = mem::zeroed();
+            c::LockFileEx(
+                self.handle.as_raw_handle(),
+                c::LOCKFILE_EXCLUSIVE_LOCK,
+                0,
+                u32::MAX,
+                u32::MAX,
+                &mut overlapped,
+            )
+        })?;
+        Ok(())
     }
 
     pub fn lock_shared(&self) -> io::Result<()> {
-        unsupported()
+        cvt(unsafe {
+            let overlapped = mem::zeroed();
+            c::LockFileEx(self.handle.as_raw_handle(), 0, 0, u32::MAX, u32::MAX, &mut overlapped)
+        })?;
+        Ok(())
     }
 
     pub fn try_lock(&self) -> io::Result<bool> {
-        unsupported()
+        let result = cvt(unsafe {
+            let overlapped = mem::zeroed();
+            c::LockFileEx(
+                self.handle.as_raw_handle(),
+                c::LOCKFILE_EXCLUSIVE_LOCK | c::LOCKFILE_FAIL_IMMEDIATELY,
+                0,
+                u32::MAX,
+                u32::MAX,
+                &mut overlapped,
+            )
+        });
+
+        if let Err(ref err) = result {
+            if err.raw_os_error() == Some(c::ERROR_IO_PENDING) {
+                return Ok(false);
+            }
+        }
+        result?;
+        Ok(true)
     }
 
     pub fn try_lock_shared(&self) -> io::Result<bool> {
-        unsupported()
+        let result = cvt(unsafe {
+            let overlapped = mem::zeroed();
+            c::LockFileEx(
+                self.handle.as_raw_handle(),
+                c::LOCKFILE_FAIL_IMMEDIATELY,
+                0,
+                u32::MAX,
+                u32::MAX,
+                &mut overlapped,
+            )
+        });
+
+        if let Err(ref err) = result {
+            if err.raw_os_error() == Some(c::ERROR_IO_PENDING) {
+                return Ok(false);
+            }
+        }
+        result?;
+        Ok(true)
     }
 
     pub fn unlock(&self) -> io::Result<()> {
-        unsupported()
+        cvt(unsafe { c::UnlockFile(self.handle.as_raw_handle(), 0, 0, u32::MAX, u32::MAX) })?;
+        Ok(())
     }
 
     pub fn truncate(&self, size: u64) -> io::Result<()> {