Fix bootstrapper getting stuck on "installing dotnet" (#5565)

src/common/common.cpp

@@ -774,28 +774,34 @@ bool find_app_name_in_path(const std::wstring& where, const std::vector<std::wst
     return false;
 }
 
-std::optional<std::string> exec_and_read_output(const std::wstring_view command, const DWORD timeout)
+std::optional<std::string> exec_and_read_output(const std::wstring_view command, DWORD timeout_ms)
 {
     SECURITY_ATTRIBUTES saAttr{ sizeof(saAttr) };
-    saAttr.bInheritHandle = true;
+    saAttr.bInheritHandle = false;
 
-    wil::unique_handle childStdoutRead;
-    wil::unique_handle childStdoutWrite;
-    if (!CreatePipe(&childStdoutRead, &childStdoutWrite, &saAttr, 0))
+    constexpr size_t bufferSize = 4096;
+    // We must use a named pipe for async I/O
+    char pipename[MAX_PATH + 1];
+    if (!GetTempFileNameA(R"(\\.\pipe\)", "tmp", 1, pipename))
     {
         return std::nullopt;
     }
 
-    if (!SetHandleInformation(childStdoutRead.get(), HANDLE_FLAG_INHERIT, 0))
+    wil::unique_handle readPipe{ CreateNamedPipeA(pipename, PIPE_ACCESS_INBOUND | FILE_FLAG_OVERLAPPED, PIPE_TYPE_BYTE | PIPE_READMODE_BYTE, PIPE_UNLIMITED_INSTANCES, bufferSize, bufferSize, 0, &saAttr) };
+
+    saAttr.bInheritHandle = true;
+    wil::unique_handle writePipe{ CreateFileA(pipename, GENERIC_WRITE, 0, &saAttr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr) };
+
+    if (!readPipe || !writePipe)
     {
         return std::nullopt;
     }
 
     PROCESS_INFORMATION piProcInfo{};
     STARTUPINFOW siStartInfo{ sizeof(siStartInfo) };
 
-    siStartInfo.hStdError = childStdoutWrite.get();
-    siStartInfo.hStdOutput = childStdoutWrite.get();
+    siStartInfo.hStdError = writePipe.get();
+    siStartInfo.hStdOutput = writePipe.get();
     siStartInfo.dwFlags |= STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
     siStartInfo.wShowWindow = SW_HIDE;
 
@@ -813,24 +819,49 @@ std::optional<std::string> exec_and_read_output(const std::wstring_view command,
     {
         return std::nullopt;
     }
+    // Child process inherited the write end of the pipe, we can close it now
+    writePipe.reset();
 
-    WaitForSingleObject(piProcInfo.hProcess, timeout);
-
-    childStdoutWrite.reset();
-    CloseHandle(piProcInfo.hThread);
+    auto closeProcessHandles = wil::scope_exit([&] {
+        CloseHandle(piProcInfo.hThread);
+        CloseHandle(piProcInfo.hProcess);
+    });
 
     std::string childOutput;
+    bool processExited = false;
     for (;;)
     {
-        char buffer[4096];
+        char buffer[bufferSize];
         DWORD gotBytes = 0;
-        if (!ReadFile(childStdoutRead.get(), buffer, sizeof(buffer), &gotBytes, nullptr) || !gotBytes)
+        wil::unique_handle IOEvent{ CreateEventW(nullptr, true, false, nullptr) };
+        OVERLAPPED overlapped{ .hEvent = IOEvent.get() };
+        ReadFile(readPipe.get(), buffer, sizeof(buffer), nullptr, &overlapped);
+
+        const std::array<HANDLE, 2> handlesToWait = { overlapped.hEvent, piProcInfo.hProcess };
+        switch (WaitForMultipleObjects(1 + !processExited, handlesToWait.data(), false, timeout_ms))
         {
-            break;
+        case WAIT_OBJECT_0 + 1:
+            if (!processExited)
+            {
+                // When the process exits, we can reduce timeout and read the rest of the output w/o possibly big timeout
+                timeout_ms = 1000;
+                processExited = true;
+                closeProcessHandles.reset();
+            }
+            [[fallthrough]];
+        case WAIT_OBJECT_0:
+            if (GetOverlappedResultEx(readPipe.get(), &overlapped, &gotBytes, timeout_ms, true))
+            {
+                childOutput += std::string_view{ buffer, gotBytes };
+                break;
+            }
+            // Timeout
+            [[fallthrough]];
+        default:
+            goto exit;
         }
-        childOutput += std::string_view{ buffer, gotBytes };
     }
-
-    CloseHandle(piProcInfo.hProcess);
+exit:
+    CancelIo(readPipe.get());
     return childOutput;
 }

src/common/common.h

@@ -99,7 +99,7 @@ std::wstring get_resource_string(UINT resource_id, HINSTANCE instance, const wch
 // is added to the .cpp file.
 #define GET_RESOURCE_STRING(resource_id) get_resource_string(resource_id, reinterpret_cast<HINSTANCE>(&__ImageBase), L#resource_id)
 
-std::optional<std::string> exec_and_read_output(const std::wstring_view command, const DWORD timeout = INFINITE);
+std::optional<std::string> exec_and_read_output(const std::wstring_view command, DWORD timeout_ms = 30000);
 
 // Helper class for various COM-related APIs, e.g working with security descriptors
 template<typename T>