From 7b5f1073419d0bca31aec9b1be6ce3e5f72b110f Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Sat, 7 Oct 2023 12:11:38 +0200
Subject: [PATCH] fs/FileInfo: add GetFileInformationByHandleEx() wrapper

---
 src/fs/FileInfo.cxx | 41 +++++++++++++++++++++++++++++++++++++++++
 src/fs/FileInfo.hxx | 15 +++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/src/fs/FileInfo.cxx b/src/fs/FileInfo.cxx
index f59e34deb..86b6904a5 100644
--- a/src/fs/FileInfo.cxx
+++ b/src/fs/FileInfo.cxx
@@ -5,6 +5,11 @@
 #include "lib/fmt/PathFormatter.hxx"
 #include "lib/fmt/SystemError.hxx"
 
+#ifdef _WIN32
+#include <windef.h> // for HWND (needed by winbase.h)
+#include <winbase.h> // for FILE_*_INFO
+#endif
+
 FileInfo::FileInfo(Path path, bool follow_symlinks)
 {
 	if (!GetFileInfo(path, *this, follow_symlinks)) {
@@ -15,3 +20,39 @@ FileInfo::FileInfo(Path path, bool follow_symlinks)
 #endif
 	}
 }
+
+#ifdef _WIN32
+
+FileInfo::FileInfo(HANDLE handle)
+{
+	if (!GetFileInfoByHandle(handle, *this))
+		throw MakeLastError("Failed to access file");
+}
+
+bool
+GetFileInfoByHandle(HANDLE handle, FileInfo &info) noexcept
+{
+	FILE_BASIC_INFO basic;
+	FILE_STANDARD_INFO standard;
+
+	if (!GetFileInformationByHandleEx(handle, FileBasicInfo,
+					  &basic, sizeof(basic)) ||
+	    !GetFileInformationByHandleEx(handle, FileStandardInfo,
+					  &standard, sizeof(standard)))
+		return false;
+
+	info.data.dwFileAttributes = basic.FileAttributes;
+	info.data.ftCreationTime.dwLowDateTime = basic.CreationTime.LowPart;
+	info.data.ftCreationTime.dwHighDateTime = basic.CreationTime.HighPart;
+	info.data.ftLastAccessTime.dwLowDateTime = basic.LastAccessTime.LowPart;
+	info.data.ftLastAccessTime.dwHighDateTime = basic.LastAccessTime.HighPart;
+	info.data.ftLastWriteTime.dwLowDateTime = basic.LastWriteTime.LowPart;
+	info.data.ftLastWriteTime.dwHighDateTime = basic.LastWriteTime.HighPart;
+
+	info.data.nFileSizeLow = standard.EndOfFile.LowPart;
+	info.data.nFileSizeHigh = standard.EndOfFile.HighPart;
+
+	return true;
+}
+
+#endif // _WIN32
diff --git a/src/fs/FileInfo.hxx b/src/fs/FileInfo.hxx
index d82a58208..25ff45a91 100644
--- a/src/fs/FileInfo.hxx
+++ b/src/fs/FileInfo.hxx
@@ -17,6 +17,10 @@
 class FileInfo {
 	friend bool GetFileInfo(Path path, FileInfo &info,
 				bool follow_symlinks) noexcept;
+#ifdef _WIN32
+	friend bool GetFileInfoByHandle(HANDLE handle, FileInfo &info) noexcept;
+#endif
+
 	friend class FileReader;
 
 #ifdef _WIN32
@@ -30,6 +34,10 @@ public:
 
 	explicit FileInfo(Path path, bool follow_symlinks=true);
 
+#ifdef _WIN32
+	explicit FileInfo(HANDLE handle);
+#endif
+
 	constexpr bool IsRegular() const noexcept {
 #ifdef _WIN32
 		return (data.dwFileAttributes &
@@ -97,3 +105,10 @@ GetFileInfo(Path path, FileInfo &info, bool follow_symlinks=true) noexcept
 	return ret == 0;
 #endif
 }
+
+#ifdef _WIN32
+
+bool
+GetFileInfoByHandle(HANDLE handle, FileInfo &info) noexcept;
+
+#endif