[newlib-cygwin] Cygwin: Add --nokill dumper option

[Jon TURNEY]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=a5218ff7721bd5df023f576a0e9afb8f099c3b09

commit a5218ff7721bd5df023f576a0e9afb8f099c3b09
Author: Jon Turney <jon.turney@dronecode.org.uk>
Date:   Mon Jul 6 14:51:32 2020 +0100

    Cygwin: Add --nokill dumper option
    
    Add --nokill option to dumper, for compatibility with minidumper, and to
    assist with testing.

Diff:
---
 winsup/doc/utils.xml   | 10 +++++++---
 winsup/utils/dumper.cc | 20 +++++++++++++++++++-
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/winsup/doc/utils.xml b/winsup/doc/utils.xml
index 8b92bfdf1..22bd86904 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 +520,12 @@ 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>For historical reasons, 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 36dbf9dbb..3eb4af275 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;