Eric Pouech : winedbg: Detect debuggee termination before first exception.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: fdd1c1c7765a2d863975fb1ed9e310f453934ec5
URL:    https://gitlab.winehq.org/wine/wine/-/commit/fdd1c1c7765a2d863975fb1ed9e310f...

Author: Eric Pouech 
Date:   Wed Jul  5 19:29:04 2023 +0200

winedbg: Detect debuggee termination before first exception.

When a crash in a program happens, and the debugger in launched in --auto
mode, in some cases the program terminates before the debugger has gotten
proper context on debuggee.
(Could be a watchdog in programs checking if it's debugged and terminating
itself if so).

Detect debuggee termination and still provide some information on debuggee
(threads, modules, system info). The backtrace will not be available as
no exception is gotten from debuggee.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55187
Signed-off-by: Eric Pouech

---

programs/winedbg/tgt_active.c | 39 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/programs/winedbg/tgt_active.c b/programs/winedbg/tgt_active.c
index a339a586eca..5ac9a4d1229 100644
--- a/programs/winedbg/tgt_active.c
+++ b/programs/winedbg/tgt_active.c
@@ -597,6 +597,26 @@ void     dbg_active_wait_for_first_exception(void)
     wait_exception();
 }

+static BOOL dbg_active_wait_for_startup(DEBUG_EVENT* de)
+{
+    dbg_interactiveP = FALSE;
+    while (dbg_num_processes() && WaitForDebugEvent(de, INFINITE))
+    {
+        switch (de->dwDebugEventCode)
+        {
+        case CREATE_PROCESS_DEBUG_EVENT:
+        case CREATE_THREAD_DEBUG_EVENT:
+        case LOAD_DLL_DEBUG_EVENT:
+        case EXCEPTION_DEBUG_EVENT:
+            if (dbg_handle_debug_event(de)) return TRUE;
+            break;
+        default:
+            return FALSE;
+        }
+    }
+    return FALSE;
+}
+
 static BOOL dbg_start_debuggee(LPSTR cmdLine)
 {
     PROCESS_INFORMATION	info;
@@ -862,6 +882,8 @@ enum dbg_start dbg_active_auto(int argc, char* argv[])
 {
     HANDLE thread = 0, event = 0, input, output = INVALID_HANDLE_VALUE;
     enum dbg_start      ds = start_error_parse;
+    BOOL first_exception = TRUE;
+    DEBUG_EVENT de;

DBG_IVAR(BreakOnDllLoad) = 0;

@@ -894,12 +916,25 @@ enum dbg_start dbg_active_auto(int argc, char* argv[])
                                          NULL);
     if (input == INVALID_HANDLE_VALUE) return start_error_parse;

-    if (dbg_curr_process->active_debuggee)
-        dbg_active_wait_for_first_exception();
+    /* debuggee can terminate before we get the first exception.
+     * so detect end of attach load sequence, and then print information.
+     */
+    if (dbg_curr_process->active_debuggee && !(first_exception = dbg_active_wait_for_startup(&de)))
+    {
+        dbg_printf("Couldn't get first exception for process %04lx %ls%s.\n"
+                   "No backtrace available\n",
+                   dbg_curr_pid, dbg_curr_process->imageName, dbg_curr_process->is_wow64 ? " (WOW64)" : "");
+    }

dbg_interactiveP = TRUE;
     parser_handle(NULL, input);

+    if (!first_exception)
+    {
+        /* continue managing debug events, in case the exception event comes after current debug event */
+        ContinueDebugEvent(de.dwProcessId, de.dwThreadId, DBG_CONTINUE);
+        dbg_active_wait_for_first_exception();
+    }
     if (output != INVALID_HANDLE_VALUE)
     {
         SetEvent( event );