forward port of windows symlink fix from RC_1_0

ChangeLog

@@ -78,6 +78,7 @@
 	* almost completely changed the storage interface (for custom storage)
 	* added support for hashing pieces in multiple threads
 
+	* fix support for symlinks on windows
 	* fix long filename issue (on unixes)
 	* fixed performance bug in DHT torrent eviction
 	* fixed win64 build (GetFileAttributesEx)

src/file.cpp

@@ -359,29 +359,39 @@ namespace libtorrent
 
 		TORRENT_UNUSED(flags);
 
-#if TORRENT_USE_WSTRING && defined TORRENT_WINDOWS
+		std::string p = convert_separators(inf);
-#define GetFileAttributesEx_ GetFileAttributesExW
+#if TORRENT_USE_UNC_PATHS
-		std::wstring f = convert_to_wstring(inf);
+		// UNC paths must be absolute
-
+		// network paths are already UNC paths
-		// apparently windows doesn't expect paths
+		if (inf.substr(0,2) == "\\\\") p = inf;
-		// to directories to ever end with a \ or /
+		else p = "\\\\?\\" + (is_complete(p) ? p : combine_path(current_working_directory(), p));
-		if (!f.empty() && (f[f.size() - 1] == L'\\'
-			|| f[f.size() - 1] == L'/'))
-			f.resize(f.size() - 1);
-#else
-#define GetFileAttributesEx_ GetFileAttributesExA
-		std::string f = convert_to_native(inf);
-
-		// apparently windows doesn't expect paths
-		// to directories to ever end with a \ or /
-		if (!f.empty() && (f[f.size() - 1] == '\\'
-			|| f[f.size() - 1] == '/'))
-			f.resize(f.size() - 1);
 #endif
-		WIN32_FILE_ATTRIBUTE_DATA data;
+
-		if (!GetFileAttributesEx_(f.c_str(), GetFileExInfoStandard, &data))
+#if TORRENT_USE_WSTRING
+#define CreateFile_ CreateFileW
+		std::wstring f = convert_to_wstring(p);
+#else
+#define CreateFile_ CreateFileA
+		std::string f = convert_to_native(p);
+#endif
+
+		// in order to open a directory, we need the FILE_FLAG_BACKUP_SEMANTICS
+		HANDLE h = CreateFile_(f.c_str(), 0, FILE_SHARE_DELETE | FILE_SHARE_READ
+			| FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+
+		if (h == INVALID_HANDLE_VALUE)
 		{
 			ec.assign(GetLastError(), system_category());
+			TORRENT_ASSERT(ec);
+			return;
+		}
+
+		BY_HANDLE_FILE_INFORMATION data;
+		if (!GetFileInformationByHandle(h, &data))
+		{
+			ec.assign(GetLastError(), system_category());
+			TORRENT_ASSERT(ec);
+			CloseHandle(h);
 			return;
 		}
 
@@ -394,9 +404,9 @@ namespace libtorrent
 			? file_status::directory
 			: (data.dwFileAttributes & FILE_ATTRIBUTE_DEVICE)
 			? file_status::character_special : file_status::regular_file;
-
+		CloseHandle(h);
 #else
-		
+
 		// posix version
 
 		std::string const& f = convert_to_native(inf);