From 87a2dba14ec82629317e13c2bce4c93b4d0a837d Mon Sep 17 00:00:00 2001 From: Alvin Wong Date: Wed, 15 Jun 2022 16:07:36 +0300 Subject: [PATCH] [lldb] Fix loading DLL from some ramdisk on Windows The WinAPI `GetFinalPathNameByHandle` is used to retrieve the DLL file name from the HANDLE provided to `LOAD_DLL_DEBUG_EVENT` in the debug loop. When this API fails, lldb will simply ignore that module. Certain ramdisk (e.g. ImDisk) does not work with this API, which means it is impossible to use lldb to debug a process which loads DLLs located on this type of ramdisk. In order to make this work, we need to use a fallback routine which involves creating a file mapping, using `GetMappedFileName` to get a device path, then substitutes the device path with its drive letter. References: * https://developercommunity.visualstudio.com/t/cannot-debug-program-when-compiled-to-ram-drive/43004#T-N109926 * https://github.com/jrfonseca/drmingw/issues/65 * https://docs.microsoft.com/en-us/windows/win32/memory/obtaining-a-file-name-from-a-file-handle Reviewed By: labath Differential Revision: https://reviews.llvm.org/D126657 --- .../Process/Windows/Common/DebuggerThread.cpp | 81 +++++++++++++++++-- 1 file changed, 73 insertions(+), 8 deletions(-) diff --git a/lldb/source/Plugins/Process/Windows/Common/DebuggerThread.cpp b/lldb/source/Plugins/Process/Windows/Common/DebuggerThread.cpp index e442650f0920..eddda6efa253 100644 --- a/lldb/source/Plugins/Process/Windows/Common/DebuggerThread.cpp +++ b/lldb/source/Plugins/Process/Windows/Common/DebuggerThread.cpp @@ -13,6 +13,7 @@ #include "lldb/Core/ModuleSpec.h" #include "lldb/Host/ProcessLaunchInfo.h" #include "lldb/Host/ThreadLauncher.h" +#include "lldb/Host/windows/AutoHandle.h" #include "lldb/Host/windows/HostProcessWindows.h" #include "lldb/Host/windows/HostThreadWindows.h" #include "lldb/Host/windows/ProcessLauncherWindows.h" @@ -29,6 +30,8 @@ #include "llvm/Support/Threading.h" #include "llvm/Support/raw_ostream.h" +#include + #ifndef STATUS_WX86_BREAKPOINT #define STATUS_WX86_BREAKPOINT 0x4000001FL // For WOW64 #endif @@ -409,6 +412,61 @@ DebuggerThread::HandleExitProcessEvent(const EXIT_PROCESS_DEBUG_INFO &info, return DBG_CONTINUE; } +static llvm::Optional GetFileNameFromHandleFallback(HANDLE hFile) { + // Check that file is not empty as we cannot map a file with zero length. + DWORD dwFileSizeHi = 0; + DWORD dwFileSizeLo = ::GetFileSize(hFile, &dwFileSizeHi); + if (dwFileSizeLo == 0 && dwFileSizeHi == 0) + return llvm::None; + + AutoHandle filemap( + ::CreateFileMappingW(hFile, nullptr, PAGE_READONLY, 0, 1, NULL), nullptr); + if (!filemap.IsValid()) + return llvm::None; + + auto view_deleter = [](void *pMem) { ::UnmapViewOfFile(pMem); }; + std::unique_ptr pMem( + ::MapViewOfFile(filemap.get(), FILE_MAP_READ, 0, 0, 1), view_deleter); + if (!pMem) + return llvm::None; + + std::array mapped_filename; + if (!::GetMappedFileNameW(::GetCurrentProcess(), pMem.get(), + mapped_filename.data(), mapped_filename.size())) + return llvm::None; + + // A series of null-terminated strings, plus an additional null character + std::array drive_strings; + drive_strings[0] = L'\0'; + if (!::GetLogicalDriveStringsW(drive_strings.size(), drive_strings.data())) + return llvm::None; + + std::array drive = {L"_:"}; + for (const wchar_t *it = drive_strings.data(); *it != L'\0'; + it += wcslen(it) + 1) { + // Copy the drive letter to the template string + drive[0] = it[0]; + std::array device_name; + if (::QueryDosDeviceW(drive.data(), device_name.data(), + device_name.size())) { + size_t device_name_len = wcslen(device_name.data()); + if (device_name_len < mapped_filename.size()) { + bool match = _wcsnicmp(mapped_filename.data(), device_name.data(), + device_name_len) == 0; + if (match && mapped_filename[device_name_len] == L'\\') { + // Replace device path with its drive letter + std::wstring rebuilt_path(drive.data()); + rebuilt_path.append(&mapped_filename[device_name_len]); + std::string path_utf8; + llvm::convertWideToUTF8(rebuilt_path, path_utf8); + return path_utf8; + } + } + } + } + return llvm::None; +} + DWORD DebuggerThread::HandleLoadDllEvent(const LOAD_DLL_DEBUG_INFO &info, DWORD thread_id) { @@ -420,6 +478,17 @@ DebuggerThread::HandleLoadDllEvent(const LOAD_DLL_DEBUG_INFO &info, return DBG_CONTINUE; } + auto on_load_dll = [&](llvm::StringRef path) { + FileSpec file_spec(path); + ModuleSpec module_spec(file_spec); + lldb::addr_t load_addr = reinterpret_cast(info.lpBaseOfDll); + + LLDB_LOG(log, "Inferior {0} - DLL '{1}' loaded at address {2:x}...", + m_process.GetProcessId(), path, info.lpBaseOfDll); + + m_debug_delegate->OnLoadDll(module_spec, load_addr); + }; + std::vector buffer(1); DWORD required_size = GetFinalPathNameByHandleW(info.hFile, &buffer[0], 0, VOLUME_NAME_DOS); @@ -434,14 +503,10 @@ DebuggerThread::HandleLoadDllEvent(const LOAD_DLL_DEBUG_INFO &info, if (path_str.startswith("\\\\?\\")) path += 4; - FileSpec file_spec(path); - ModuleSpec module_spec(file_spec); - lldb::addr_t load_addr = reinterpret_cast(info.lpBaseOfDll); - - LLDB_LOG(log, "Inferior {0} - DLL '{1}' loaded at address {2:x}...", - m_process.GetProcessId(), path, info.lpBaseOfDll); - - m_debug_delegate->OnLoadDll(module_spec, load_addr); + on_load_dll(path); + } else if (llvm::Optional path = + GetFileNameFromHandleFallback(info.hFile)) { + on_load_dll(*path); } else { LLDB_LOG( log,