[PATCH 0/3] Misc dumper improvements

[PATCH 0/3] Misc dumper improvements

[Jon Turney]

Jon Turney (3):
  Cygwin: Add --nokill dumper option
  CYgwin: Remove synchronization event from dumper
  Cygwin: Speed up dumper

 winsup/doc/utils.xml   |  9 ++++++---
 winsup/utils/dumper.cc | 41 +++++++++++++++++++++--------------------
 2 files changed, 27 insertions(+), 23 deletions(-)

-- 
2.27.0

[PATCH 1/3] Cygwin: Add --nokill dumper option

[Jon Turney]

Add --nokill option to dumper, for compatibility with minidumper, and to
assist with testing.
---
 winsup/doc/utils.xml   |  9 ++++++---
 winsup/utils/dumper.cc | 20 +++++++++++++++++++-
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/winsup/doc/utils.xml b/winsup/doc/utils.xml
index 8b92bfdf1..176f9a0d3 100644
--- a/winsup/doc/utils.xml
+++ b/winsup/doc/utils.xml
@@ -496,6 +496,7 @@ dumper [OPTION] FILENAME WIN32PID
     <refsect1 id="dumper-options">
       <title>Options</title>
       <screen>
+-n, --nokill   don't terminate the dumped process
 -d, --verbose  be verbose while dumping
 -h, --help     output help information and exit
 -q, --quiet    be quiet while dumping (default)
@@ -519,9 +520,11 @@ error_start=x:\path\to\dumper.exe
       be started whenever some program encounters a fatal error. </para>
 
     <para> <command>dumper</command> can be also be started from the command
-      line to create a core dump of any running process. Unfortunately, because
-      of a Windows API limitation, when a core dump is created and
-      <command>dumper</command> exits, the target process is terminated too. </para>
+      line to create a core dump of any running process.</para>
+
+    <para>Unless the <literal>-n</literal> option is given, after the core dump
+    is created and when the <command>dumper</command> exits, the target process
+    is also terminated.</para>
 
     <para> To save space in the core dump, <command>dumper</command> doesn't
       write those portions of the target process's memory space that are loaded
diff --git a/winsup/utils/dumper.cc b/winsup/utils/dumper.cc
index 3af138b9e..fa6d9641a 100644
--- a/winsup/utils/dumper.cc
+++ b/winsup/utils/dumper.cc
@@ -64,6 +64,7 @@ __attribute__ ((packed))
   note_header;
 
 BOOL verbose = FALSE;
+BOOL nokill = FALSE;
 
 int deb_printf (const char *format,...)
 {
@@ -716,7 +717,19 @@ dumper::collect_process_information ()
 			  current_event.dwThreadId,
 			  DBG_CONTINUE);
     }
+
 failed:
+  if (nokill)
+    {
+      if (!DebugActiveProcessStop (pid))
+	{
+	  fprintf (stderr, "Cannot detach from process #%u, error %ld",
+		   (unsigned int) pid, (long) GetLastError ());
+	}
+    }
+  /* Otherwise, the debuggee is terminated when this process exits
+     (as DebugSetProcessKillOnExit() defaults to TRUE) */
+
   /* set debugee free */
   if (sync_with_debugee)
     SetEvent (sync_with_debugee);
@@ -960,6 +973,7 @@ Usage: %s [OPTION] FILENAME WIN32PID\n\
 \n\
 Dump core from WIN32PID to FILENAME.core\n\
 \n\
+ -n, --nokill   don't terminate the dumped process\n\
  -d, --verbose  be verbose while dumping\n\
  -h, --help     output help information and exit\n\
  -q, --quiet    be quiet while dumping (default)\n\
@@ -969,13 +983,14 @@ Dump core from WIN32PID to FILENAME.core\n\
 }
 
 struct option longopts[] = {
+  {"nokill", no_argument, NULL, 'n'},
   {"verbose", no_argument, NULL, 'd'},
   {"help", no_argument, NULL, 'h'},
   {"quiet", no_argument, NULL, 'q'},
   {"version", no_argument, 0, 'V'},
   {0, no_argument, NULL, 0}
 };
-const char *opts = "dhqV";
+const char *opts = "ndhqV";
 
 static void
 print_version ()
@@ -1001,6 +1016,9 @@ main (int argc, char **argv)
   while ((opt = getopt_long (argc, argv, opts, longopts, NULL) ) != EOF)
     switch (opt)
       {
+      case 'n':
+	nokill = TRUE;
+	break;
       case 'd':
 	verbose = TRUE;
 	break;
-- 
2.27.0

[PATCH 2/3] CYgwin: Remove synchronization event from dumper

[Jon Turney]

The use of the 'cygwin_error_start_event' for synchronization with
dumper was removed from the DLL in commit 8abeff1e (April 2001).
---
 winsup/utils/dumper.cc | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/winsup/utils/dumper.cc b/winsup/utils/dumper.cc
index fa6d9641a..ace752464 100644
--- a/winsup/utils/dumper.cc
+++ b/winsup/utils/dumper.cc
@@ -627,10 +627,6 @@ dumper::collect_process_information ()
       return 0;
     }
 
-  char event_name[sizeof ("cygwin_error_start_event") + 20];
-  sprintf (event_name, "cygwin_error_start_event%16x", (unsigned int) pid);
-  HANDLE sync_with_debugee = OpenEvent (EVENT_MODIFY_STATE, FALSE, event_name);
-
   DEBUG_EVENT current_event;
 
   while (1)
@@ -701,10 +697,6 @@ dumper::collect_process_information ()
 	      goto failed;
 	    };
 
-	  /* signal a debugee that we've finished */
-	  if (sync_with_debugee)
-	    SetEvent (sync_with_debugee);
-
 	  break;
 
 	default:
@@ -730,10 +722,6 @@ failed:
   /* Otherwise, the debuggee is terminated when this process exits
      (as DebugSetProcessKillOnExit() defaults to TRUE) */
 
-  /* set debugee free */
-  if (sync_with_debugee)
-    SetEvent (sync_with_debugee);
-
   return 0;
 }
 
-- 
2.27.0

[PATCH 3/3] Cygwin: Speed up dumper

[Jon Turney]

Stop after we've written the dump in response to the initial breakpoint
EXCEPTION_DEBUG_EVENT we recieve for attaching to the process.

(rather than bogusly sitting there for 20 seconds waiting for more debug
events from a stopped process after we've already written the dump).
---
 winsup/utils/dumper.cc | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/winsup/utils/dumper.cc b/winsup/utils/dumper.cc
index ace752464..e80758e0c 100644
--- a/winsup/utils/dumper.cc
+++ b/winsup/utils/dumper.cc
@@ -615,8 +615,6 @@ out:
 int
 dumper::collect_process_information ()
 {
-  int exception_level = 0;
-
   if (!sane ())
     return 0;
 
@@ -631,7 +629,7 @@ dumper::collect_process_information ()
 
   while (1)
     {
-      if (!WaitForDebugEvent (&current_event, 20000))
+      if (!WaitForDebugEvent (&current_event, INFINITE))
 	return 0;
 
       deb_printf ("got debug event %d\n", current_event.dwDebugEventCode);
@@ -675,12 +673,6 @@ dumper::collect_process_information ()
 
 	case EXCEPTION_DEBUG_EVENT:
 
-	  exception_level++;
-	  if (exception_level == 2)
-	    break;
-	  else if (exception_level > 2)
-	    return 0;
-
 	  collect_memory_sections ();
 
 	  /* got all info. time to dump */
@@ -697,6 +689,9 @@ dumper::collect_process_information ()
 	      goto failed;
 	    };
 
+	  /* We're done */
+	  goto failed;
+
 	  break;
 
 	default:
-- 
2.27.0