From 00999694f9ce98ad7ef54b66c9e82186edcf55a6 Mon Sep 17 00:00:00 2001
From: Egor Tensin <Egor.Tensin@gmail.com>
Date: Sun, 18 Oct 2020 23:59:02 +0300
Subject: Process: add runas()

---
 include/winapi/process.hpp  |  2 ++
 src/process.cpp             | 31 +++++++++++++++++++++++++++++++
 test/unit_tests/process.cpp |  7 +++++++
 3 files changed, 40 insertions(+)

diff --git a/include/winapi/process.hpp b/include/winapi/process.hpp
index d52ad0a..05411cd 100644
--- a/include/winapi/process.hpp
+++ b/include/winapi/process.hpp
@@ -24,6 +24,8 @@ public:
     static Process create(const CommandLine&);
     static Process create(const CommandLine&, process::IO);
 
+    static Process runas(const CommandLine&);
+
     void wait() const;
 
     int get_exit_code() const;
diff --git a/src/process.cpp b/src/process.cpp
index 9fe19e5..a9f24cc 100644
--- a/src/process.cpp
+++ b/src/process.cpp
@@ -12,7 +12,10 @@
 
 #include <boost/config.hpp>
 
+// clang-format off
 #include <windows.h>
+#include <shellapi.h>
+// clang-format on
 
 #include <cstddef>
 #include <cstring>
@@ -69,6 +72,30 @@ Handle create_process(const CommandLine& cmd_line, process::IO& io) {
     return create_process(escape_command_line(cmd_line), io);
 }
 
+Handle shell_execute(const CommandLine& cmd_line) {
+    BOOST_STATIC_CONSTEXPR unsigned long flags =
+        SEE_MASK_NOCLOSEPROCESS | SEE_MASK_FLAG_NO_UI | SEE_MASK_NO_CONSOLE;
+
+    const auto exe_path = widen(cmd_line.get_argv0());
+    const auto args = widen(cmd_line.args_to_string());
+
+    SHELLEXECUTEINFOW info;
+    std::memset(&info, 0, sizeof(info));
+    info.cbSize = sizeof(info);
+    info.fMask = flags;
+    info.lpVerb = L"runas";
+    info.lpFile = exe_path.c_str();
+    if (!args.empty())
+        info.lpParameters = args.c_str();
+    info.nShow = SW_SHOWDEFAULT;
+
+    if (!::ShellExecuteExW(&info)) {
+        throw error::windows(GetLastError(), "ShellExecuteExW");
+    }
+
+    return Handle{info.hProcess};
+}
+
 } // namespace
 
 Process Process::create(const CommandLine& cmd_line) {
@@ -79,6 +106,10 @@ Process Process::create(const CommandLine& cmd_line, process::IO io) {
     return Process{create_process(cmd_line, io)};
 }
 
+Process Process::runas(const CommandLine& cmd_line) {
+    return Process{shell_execute(cmd_line)};
+}
+
 void Process::wait() const {
     const auto ret = ::WaitForSingleObject(static_cast<HANDLE>(m_handle), INFINITE);
 
diff --git a/test/unit_tests/process.cpp b/test/unit_tests/process.cpp
index a126f86..715364f 100644
--- a/test/unit_tests/process.cpp
+++ b/test/unit_tests/process.cpp
@@ -82,4 +82,11 @@ BOOST_FIXTURE_TEST_CASE(echo_stdin_from_file, WithEchoExe) {
     BOOST_TEST(stdout8 == stdin8);
 }
 
+BOOST_FIXTURE_TEST_CASE(echo_runas, WithEchoExe) {
+    const CommandLine cmd_line{get_echo_exe(), {"foo", "bar"}};
+    const auto process = Process::runas(cmd_line);
+    process.wait();
+    BOOST_TEST(process.get_exit_code() == 0);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
-- 
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