On Feb  8 14:06, Corinna Vinschen wrote:
> On Feb  8 13:52, Michael Haubenwallner wrote:
> > On 2/8/19 1:23 PM, Corinna Vinschen wrote:
> > > On Feb  8 13:21, Corinna Vinschen wrote:
> > >> On Feb  8 12:51, Michael Haubenwallner wrote:
> > >>>
> > >>> For now it seems like there's an inconsistency with PIDs:
> > >>> A first process PID 100, receives PID 101 from spawn(),
> > >>> but in the new process getpid() returns 102:
> > >>>
> > >>> $ ./dospawn /bin/bash -c 'echo $$'
> > >>> 12625
> > >>> waitpid: pid 12624 status 0x0
> > >>
> > >> Oh, hmm.  If you call spawnve, rather than execve, a new child pid
> > >> is generated in spawnve, rather than just keeping the callers pid.
> > >>
> > >> However, apparently the child invents its own pid in pinfo::thisproc
> > >> after being spawned.  But actually this should only occur for forked
> > >> processes aore processes started from non-Cygwin parents.
> > > 
> > > Does that help, by any chance:
> > > [nope]
> > 
> > How should the child be informed at all about the new cygpid value generated in
> > parent's child_info_spawn::worker() ?
> 
> I just realized this myself.  The old method creating Cygwin pids just
> fetched the pid from GetCurrentProcessId(), which was right for spawned
> (but not execed) processes.  For the new pid we might have to give this
> to the child via child_info_spawn.

This works for me, can you test this, too, please?

diff --git a/winsup/cygwin/child_info.h b/winsup/cygwin/child_info.h
index 67264119eae9..847614ff299a 100644
--- a/winsup/cygwin/child_info.h
+++ b/winsup/cygwin/child_info.h
@@ -144,6 +144,7 @@ class child_info_spawn: public child_info
 {
   HANDLE hExeced;
   HANDLE ev;
+  pid_t cygpid;
 public:
   cygheap_exec_info *moreinfo;
   int __stdin;
diff --git a/winsup/cygwin/dcrt0.cc b/winsup/cygwin/dcrt0.cc
index 78506d43de29..11edcdf0d21b 100644
--- a/winsup/cygwin/dcrt0.cc
+++ b/winsup/cygwin/dcrt0.cc
@@ -652,11 +652,16 @@ child_info_spawn::handle_spawn ()
 	cygheap_fixup_in_child (true);
 	memory_init ();
       }
+
+  cygheap->pid = cygpid;
+
+  /* Spawned process sets h to INVALID_HANDLE_VALUE to notify
+     pinfo::thisproc not to create another pid. */
   if (!moreinfo->myself_pinfo ||
       !DuplicateHandle (GetCurrentProcess (), moreinfo->myself_pinfo,
 			GetCurrentProcess (), &h, 0,
 			FALSE, DUPLICATE_SAME_ACCESS | DUPLICATE_CLOSE_SOURCE))
-    h = NULL;
+    h = (type == _CH_SPAWN) ? INVALID_HANDLE_VALUE : NULL;
 
   /* Setup our write end of the process pipe.  Clear the one in the structure.
      The destructor should never be called for this but, it can't hurt to be
diff --git a/winsup/cygwin/pinfo.cc b/winsup/cygwin/pinfo.cc
index 445bd35b224e..61fbc9bc19bf 100644
--- a/winsup/cygwin/pinfo.cc
+++ b/winsup/cygwin/pinfo.cc
@@ -57,11 +57,15 @@ pinfo::thisproc (HANDLE h)
   procinfo = NULL;
 
   DWORD flags = PID_IN_USE | PID_ACTIVE;
+  /* Forked process or process started from non-Cygwin parent needs a pid. */
   if (!h)
     {
       cygheap->pid = create_cygwin_pid ();
       flags |= PID_NEW;
     }
+  /* spawnve'd process got pid from parent. */
+  else if (h == INVALID_HANDLE_VALUE)
+    h = NULL;
 
   init (cygheap->pid, flags, h);
   procinfo->process_state |= PID_IN_USE;
diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index d969c66ea19a..ebc34d10542f 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -258,7 +258,6 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 			  int in__stdin, int in__stdout)
 {
   bool rc;
-  pid_t cygpid;
   int res = -1;
 
   /* Check if we have been called from exec{lv}p or spawn{lv}p and mask
@@ -578,6 +577,8 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
       if (!real_path.iscygexec () && mode == _P_OVERLAY)
 	myself->process_state |= PID_NOTCYGWIN;
 
+      cygpid = (mode != _P_OVERLAY) ? create_cygwin_pid () : myself->pid;
+
       wchar_t wcmd[(size_t) cmd];
       if (!::cygheap->user.issetuid ()
 	  || (::cygheap->user.saved_uid == ::cygheap->user.real_uid
@@ -708,11 +709,6 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
       if (::cygheap->fdtab.need_fixup_before ())
 	::cygheap->fdtab.fixup_before_exec (pi.dwProcessId);
 
-      if (mode != _P_OVERLAY)
-	cygpid = create_cygwin_pid ();
-      else
-	cygpid = myself->pid;
-
       /* Print the original program name here so the user can see that too.  */
       syscall_printf ("pid %d, prog_arg %s, cmd line %.9500s)",
 		      rc ? cygpid : (unsigned int) -1, prog_arg, (const char *) cmd);


I pushed your forkable branch to master, btw.  Would you mind to do the
honors in the ;rease notes at cygwin/release/3.0 and doc/new-features.xml?


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer