[llvm] [Support] Handle delete_pending case for Windows fs::status (PR #90655)

[Jeremy Day via llvm-commits]

https://github.com/z2oh updated https://github.com/llvm/llvm-project/pull/90655

>From 078ba3cea20bc91a60c9daa07df764d72dfd282e Mon Sep 17 00:00:00 2001
From: Jeremy Day <jeremy at thebrowser.company>
Date: Tue, 30 Apr 2024 12:53:40 -0700
Subject: [PATCH] [Support] Handle delete_pending case for Windows fs::status

If a delete is pending on the file queried for status, a misleading `permission_denied` error code will be returned (this is the correct mapping of the error set by GetFileAttributesW). By querying the underlying NTSTATUS code via ntdll's RtlGetLastNtStatus, this case can be disambiguated. If this underlying error code indicates a pending delete, fs::status will return a new `pending_delete` error code to be handled by callers
---
 llvm/include/llvm/Support/Errc.h         |  4 +++
 llvm/include/llvm/Support/WindowsError.h |  1 +
 llvm/lib/Support/CMakeLists.txt          |  3 +-
 llvm/lib/Support/ErrorHandling.cpp       | 35 ++++++++++++++++++++++++
 llvm/lib/Support/Windows/Path.inc        |  8 +++---
 5 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/llvm/include/llvm/Support/Errc.h b/llvm/include/llvm/Support/Errc.h
index 9df522cbe45c7..fcb69d303109a 100644
--- a/llvm/include/llvm/Support/Errc.h
+++ b/llvm/include/llvm/Support/Errc.h
@@ -38,6 +38,10 @@ enum class errc {
   bad_address = int(std::errc::bad_address),
   bad_file_descriptor = int(std::errc::bad_file_descriptor),
   broken_pipe = int(std::errc::broken_pipe),
+  // There is no delete_pending in std::errc; this error code is negative to
+  // avoid conflicts. This error roughly corresponds with Windows'
+  // STATUS_DELETE_PENDING 0xC0000056.
+  delete_pending = -56,
   device_or_resource_busy = int(std::errc::device_or_resource_busy),
   directory_not_empty = int(std::errc::directory_not_empty),
   executable_format_error = int(std::errc::executable_format_error),
diff --git a/llvm/include/llvm/Support/WindowsError.h b/llvm/include/llvm/Support/WindowsError.h
index 1954052241243..d11e9019f5815 100644
--- a/llvm/include/llvm/Support/WindowsError.h
+++ b/llvm/include/llvm/Support/WindowsError.h
@@ -12,6 +12,7 @@
 #include <system_error>
 
 namespace llvm {
+std::error_code mapLastWindowsError();
 std::error_code mapWindowsError(unsigned EV);
 }
 
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 03e888958a071..5d50462ec03d7 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -40,7 +40,8 @@ endif()
 if( MSVC OR MINGW )
   # libuuid required for FOLDERID_Profile usage in lib/Support/Windows/Path.inc.
   # advapi32 required for CryptAcquireContextW in lib/Support/Windows/Path.inc.
-  set(system_libs ${system_libs} psapi shell32 ole32 uuid advapi32 ws2_32)
+  # ntdll required for RtlGetLastNtStatus in lib/Support/ErrorHandling.cpp.
+  set(system_libs ${system_libs} psapi shell32 ole32 uuid advapi32 ws2_32 ntdll)
 elseif( CMAKE_HOST_UNIX )
   if( HAVE_LIBRT )
     set(system_libs ${system_libs} rt)
diff --git a/llvm/lib/Support/ErrorHandling.cpp b/llvm/lib/Support/ErrorHandling.cpp
index d2d3dcc2f478c..cb42e28c04a86 100644
--- a/llvm/lib/Support/ErrorHandling.cpp
+++ b/llvm/lib/Support/ErrorHandling.cpp
@@ -236,8 +236,43 @@ void LLVMResetFatalErrorHandler() {
 
 #ifdef _WIN32
 
+#define WIN32_NO_STATUS
+#include "llvm/Support/Windows/WindowsSupport.h"
+#undef WIN32_NO_STATUS
+#include <ntstatus.h>
 #include <winerror.h>
 
+// This is equivalent to NtCurrentTeb()->LastStatusValue, but the public
+// _TEB definition does not expose the LastStatusValue field directly.
+// Avoid offsetting into this structure by calling RtlGetLastNtStatus
+// from ntdll.dll.
+//
+// The return of this function will roughly match that of
+// GetLastError, but this lower level API disambiguates some cases
+// that GetLastError does not.
+//
+// For more information, see:
+// https://www.geoffchappell.com/studies/windows/km/ntoskrnl/inc/api/pebteb/teb/index.htm
+// https://github.com/llvm/llvm-project/issues/89137
+extern "C" NTSYSAPI NTSTATUS NTAPI RtlGetLastNtStatus();
+
+// This function obtains the last error code and maps it. It may call
+// RtlGetLastNtStatus, which is a lower level API that can return a
+// more specific error code than GetLastError.
+std::error_code llvm::mapLastWindowsError() {
+  unsigned EV = ::GetLastError();
+  // The mapping of NTSTATUS to Win32 error loses some information; special
+  // case the generic ERROR_ACCESS_DENIED code to check the underlying
+  // NTSTATUS and potentially return a more accurate error code.
+  if (EV == ERROR_ACCESS_DENIED) {
+    llvm::errc code = RtlGetLastNtStatus() == STATUS_DELETE_PENDING
+                          ? errc::delete_pending
+                          : errc::permission_denied;
+    return make_error_code(code);
+  }
+  return mapWindowsError(EV);
+}
+
 // I'd rather not double the line count of the following.
 #define MAP_ERR_TO_COND(x, y)                                                  \
   case x:                                                                      \
diff --git a/llvm/lib/Support/Windows/Path.inc b/llvm/lib/Support/Windows/Path.inc
index 4f0336a85daaa..c4bd5e2472351 100644
--- a/llvm/lib/Support/Windows/Path.inc
+++ b/llvm/lib/Support/Windows/Path.inc
@@ -760,14 +760,14 @@ static std::error_code getStatus(HANDLE FileHandle, file_status &Result) {
   return std::error_code();
 
 handle_status_error:
-  DWORD LastError = ::GetLastError();
-  if (LastError == ERROR_FILE_NOT_FOUND || LastError == ERROR_PATH_NOT_FOUND)
+  std::error_code Err = mapLastWindowsError();
+  if (Err == std::errc::no_such_file_or_directory)
     Result = file_status(file_type::file_not_found);
-  else if (LastError == ERROR_SHARING_VIOLATION)
+  else if (Err == std::errc::permission_denied)
     Result = file_status(file_type::type_unknown);
   else
     Result = file_status(file_type::status_error);
-  return mapWindowsError(LastError);
+  return Err;
 }
 
 std::error_code status(const Twine &path, file_status &result, bool Follow) {