From bb2a72f67f4b90e1b31ccbc0f3c3ea9b280d2ffd Mon Sep 17 00:00:00 2001
From: Martin Pulec <martin.pulec@cesnet.cz>
Date: Fri, 26 Jan 2024 15:04:53 +0100
Subject: [PATCH] issue a warning in legacy W10 terminals (PS/cmd)

Those terminal emulators block stdout/stderr output when scrolled,
which effectively stops UltraGrid. The behavior doesn't occur in MS
Terminal app, which is encouraged instead.

Note that Windows Terminal still runs cmd.exe or powershell.exe as a shell
while the cmd/PS process can acts like both terminal emulator and
shell. We also do not trigger the warning if UG is run from within
MSYS2 terminal.
---
 src/host.cpp        | 12 ++++++++++
 src/utils/windows.c | 56 ++++++++++++++++++++++++++++++++++++++-------
 src/utils/windows.h |  1 +
 3 files changed, 61 insertions(+), 8 deletions(-)

diff --git a/src/host.cpp b/src/host.cpp
index 106296917..a5ab09755 100644
--- a/src/host.cpp
+++ b/src/host.cpp
@@ -116,6 +116,8 @@ extern "C" {
 #include <mcheck.h>
 #endif
 
+#define MOD_NAME "[host] "
+
 using std::array;
 using std::cout;
 using std::endl;
@@ -458,6 +460,16 @@ struct init_data *common_preinit(int argc, char *argv[])
         if (init_com) {
                 com_initialize(&init.com_initialized, nullptr);
         }
+
+        // warn in W10 "legacy" terminal emulators
+        if ((win_has_ancestor_process("powershell.exe") ||
+             win_has_ancestor_process("cmd.exe")) &&
+            !win_has_ancestor_process("WindowsTerminal.exe")) {
+                MSG(WARNING, "Running inside PS/cmd terminal is not recommended "
+                             "because scrolling the output freezes the process, "
+                             "consider using Windows Terminal instead!\n");
+                Sleep(1000);
+        }
 #endif
 
         if (strstr(argv[0], "run_tests") == nullptr) {
diff --git a/src/utils/windows.c b/src/utils/windows.c
index a3f0ea296..ce099b8d5 100644
--- a/src/utils/windows.c
+++ b/src/utils/windows.c
@@ -35,21 +35,18 @@
  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#include "config_unix.h"
-#include "config_win32.h"
-#endif
-
-#include "utils/windows.h"
-
 #ifdef _WIN32
 #include <audioclient.h>
 #include <objbase.h>
+#include <tlhelp32.h>
 #include <vfwmsgs.h>
 #include "debug.h"
 #endif // defined _WIN32
 
+#include "utils/windows.h"
+
+#define MOD_NAME "[utils/win] "
+
 bool com_initialize(bool *com_initialized, const char *err_prefix)
 {
 #ifdef _WIN32
@@ -183,6 +180,49 @@ const char *win_wstr_to_str(const wchar_t *wstr) {
         }
         return res;
 }
+
+static bool
+GetProcessInfo(HANDLE hSnapshot, DWORD processId, PROCESSENTRY32 *pe32)
+{
+        if (!Process32First(hSnapshot, pe32)) {
+                return false;
+        }
+
+        do {
+                if (pe32->th32ProcessID == processId) {
+                        return true;
+                }
+        } while (Process32Next(hSnapshot, pe32));
+
+        return false;
+}
+
+/**
+ * @returns true if there is a process "name" among current process ancestors
+ * @param name the searched process name (case insensitive)
+ */
+bool
+win_has_ancestor_process(const char *name)
+{
+        HANDLE hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
+        if (hSnapshot == INVALID_HANDLE_VALUE) {
+                return false;
+        }
+        DWORD          pid  = GetCurrentProcessId();
+        PROCESSENTRY32 pe32 = { .dwSize = sizeof(PROCESSENTRY32) };
+        while (GetProcessInfo(hSnapshot, pid, &pe32)) {
+                MSG(DEBUG, "%s: %s PID: %ld, PPID: %ld\n", __func__
+                    pe32.szExeFile, pid, pe32.th32ParentProcessID);
+                if (_stricmp(pe32.szExeFile, name) == 0) {
+                        CloseHandle(hSnapshot);
+                        return true;
+                }
+                pid = pe32.th32ParentProcessID;
+        }
+        CloseHandle(hSnapshot);
+        return false;
+}
+
 #endif // defined _WIN32
 
 /* vim: set expandtab sw=8 tw=120: */
diff --git a/src/utils/windows.h b/src/utils/windows.h
index 1e5fd01d3..41c3859c3 100644
--- a/src/utils/windows.h
+++ b/src/utils/windows.h
@@ -85,6 +85,7 @@ void com_uninitialize(bool *com_initialized);
 const char *hresult_to_str(HRESULT res);
 const char *get_win32_error(DWORD error);
 const char *win_wstr_to_str(const wchar_t *wstr);
+bool win_has_ancestor_process(const char *name);
 #endif // defined _WIN32
 
 #ifdef __cplusplus