diff options
Diffstat (limited to 'other-licenses/nsis/Contrib/ExecInExplorer/ExecInExplorer.cpp')
| -rw-r--r-- | other-licenses/nsis/Contrib/ExecInExplorer/ExecInExplorer.cpp | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/other-licenses/nsis/Contrib/ExecInExplorer/ExecInExplorer.cpp b/other-licenses/nsis/Contrib/ExecInExplorer/ExecInExplorer.cpp new file mode 100644 index 0000000000..05e0ed5e92 --- /dev/null +++ b/other-licenses/nsis/Contrib/ExecInExplorer/ExecInExplorer.cpp @@ -0,0 +1,212 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, you can obtain one at http://mozilla.org/MPL/2.0/. */ + +// This file is an NSIS plugin which exports a function that starts a process +// from a provided path by using the shell automation API to have explorer.exe +// invoke ShellExecute. This roundabout method of starting a process is useful +// because it means the new process will use the integrity level and security +// token of the shell, so it allows starting an unelevated process from inside +// an elevated one. The method is based on +// https://blogs.msdn.microsoft.com/oldnewthing/20131118-00/?p=2643 +// but the code has been rewritten to remove the need for ATL or the C runtime. + +// Normally an NSIS installer would use the UAC plugin, which itself uses both +// an unelevated and an elevated process, and the elevated process can invoke +// functions in the unelevated one, so this plugin wouldn't be needed. +// But uninstallers are often directly run elevated because that's just how +// the Windows UI launches them, so there is no unelevated process. This +// plugin allows starting a needed unelevated process in that situation. + +#include <windows.h> +#include <shlobj.h> + +#pragma comment(lib, "shlwapi.lib") + +static IShellView* +GetDesktopWindowShellView() +{ + IShellView* view = nullptr; + IShellWindows* shell = nullptr; + CoCreateInstance(CLSID_ShellWindows, NULL, CLSCTX_LOCAL_SERVER, + IID_PPV_ARGS(&shell)); + if (shell) { + VARIANT empty; + VariantInit(&empty); + + VARIANT loc; + loc.vt = VT_VARIANT | VT_BYREF; + PIDLIST_ABSOLUTE locList; + SHGetFolderLocation(nullptr, CSIDL_DESKTOP, nullptr, 0, &locList); + loc.byref = locList; + + HWND windowHandle = 0; + IDispatch* dispatch = nullptr; + + shell->FindWindowSW(&loc, &empty, SWC_DESKTOP, (long*)&windowHandle, + SWFO_NEEDDISPATCH, &dispatch); + if (dispatch) { + IServiceProvider* provider = nullptr; + dispatch->QueryInterface(IID_PPV_ARGS(&provider)); + if (provider) { + IShellBrowser* browser = nullptr; + provider->QueryService(SID_STopLevelBrowser, IID_PPV_ARGS(&browser)); + if (browser) { + browser->QueryActiveShellView(&view); + browser->Release(); + } + provider->Release(); + } + dispatch->Release(); + } + shell->Release(); + } + + return view; +} + +static IShellDispatch2* +GetApplicationFromShellView(IShellView* view) +{ + IShellDispatch2* shellDispatch = nullptr; + IDispatch* viewDisp = nullptr; + HRESULT hr = view->GetItemObject(SVGIO_BACKGROUND, IID_PPV_ARGS(&viewDisp)); + if (SUCCEEDED(hr)) { + IShellFolderViewDual* shellViewFolder = nullptr; + viewDisp->QueryInterface(IID_PPV_ARGS(&shellViewFolder)); + if (shellViewFolder) { + IDispatch* dispatch = nullptr; + shellViewFolder->get_Application(&dispatch); + if (dispatch) { + dispatch->QueryInterface(IID_PPV_ARGS(&shellDispatch)); + dispatch->Release(); + } + shellViewFolder->Release(); + } + viewDisp->Release(); + } + return shellDispatch; +} + +static bool +ShellExecInExplorerProcess(wchar_t* path, wchar_t* args = nullptr) +{ + bool rv = false; + if (SUCCEEDED(CoInitialize(nullptr))) { + IShellView *desktopView = GetDesktopWindowShellView(); + if (desktopView) { + IShellDispatch2 *shellDispatch = GetApplicationFromShellView(desktopView); + if (shellDispatch) { + BSTR bstrPath = SysAllocString(path); + VARIANT vArgs; + VariantInit(&vArgs); + if (args) { + vArgs.vt = VT_BSTR; + vArgs.bstrVal = SysAllocString(args); + } + rv = SUCCEEDED(shellDispatch->ShellExecuteW(bstrPath, vArgs, VARIANT{}, + VARIANT{}, VARIANT{})); + VariantClear(&vArgs); + SysFreeString(bstrPath); + shellDispatch->Release(); + } + desktopView->Release(); + } + CoUninitialize(); + } + return rv; +} + +struct stack_t { + stack_t* next; + TCHAR text[MAX_PATH]; +}; + +/** + * Removes an element from the top of the NSIS stack + * + * @param stacktop A pointer to the top of the stack + * @param str The string to pop to + * @param len The max length + * @return 0 on success + */ +int +popstring(stack_t **stacktop, TCHAR *str, int len) +{ + // Removes the element from the top of the stack and puts it in the buffer + stack_t *th; + if (!stacktop || !*stacktop) { + return 1; + } + + th = (*stacktop); + lstrcpyn(str, th->text, len); + *stacktop = th->next; + HeapFree(GetProcessHeap(), 0, th); + return 0; +} + +/** + * Adds an element to the top of the NSIS stack + * + * @param stacktop A pointer to the top of the stack + * @param str The string to push on the stack + * @param len The length of the string to push on the stack + * @return 0 on success + */ +void +pushstring(stack_t **stacktop, const TCHAR *str, int len) +{ + stack_t *th; + if (!stacktop) { + return; + } + th = (stack_t*)HeapAlloc(GetProcessHeap(), 0, sizeof(stack_t) + len); + lstrcpyn(th->text, str, len); + th->next = *stacktop; + *stacktop = th; +} + +/** +* Starts an executable or URL from the shell process. +* +* @param stacktop Pointer to the top of the stack, AKA the first parameter to + the plugin call. Should contain the file or URL to execute. +* @return 1 if the file/URL was executed successfully, 0 if it was not +*/ +extern "C" void __declspec(dllexport) +Exec(HWND, int, TCHAR *, stack_t **stacktop, void *) +{ + wchar_t path[MAX_PATH + 1]; + wchar_t args[MAX_PATH + 1]; + bool rv = false; + bool restoreArgString = false; + // We're skipping building the C runtime to keep the file size low, so we + // can't use a normal string initialization because that would call memset. + path[0] = L'\0'; + args[0] = L'\0'; + popstring(stacktop, path, MAX_PATH); + if (popstring(stacktop, args, MAX_PATH) == 0) { + // This stack item may not be for us, but we don't know yet. + restoreArgString = true; + } + + if (lstrcmpW(args, L"/cmdargs") == 0) { + popstring(stacktop, args, MAX_PATH); + rv = ShellExecInExplorerProcess(path, args); + } else { + // If the stack wasn't empty, then we popped something that wasn't for us. + if (restoreArgString) { + pushstring(stacktop, args, lstrlenW(args)); + } + rv = ShellExecInExplorerProcess(path); + } + + pushstring(stacktop, rv ? L"1" : L"0", 2); +} + +BOOL APIENTRY +DllMain(HMODULE, DWORD, LPVOID) +{ + return TRUE; +} |