[PATCH v7 2/3] Cygwin: spawn: Lock cygheap from refresh_cygheap() until child_copy()

[Takashi Yano]

...completion in child process because the cygheap should not be
changed to avoid mismatch between child_info::cygheap_max and
::cygheap_max. Otherwise, child_copy() might copy cygheap being
modified by other process.

In addition, to avoid deadlock, move close_all_files() for non-
Cygwin processes after unlocking cygheap, since close_all_files()
calls cfree(), which attempts to lock cygheap even when it's already
locked.

Fixes: 977ad5434cc0 ("* spawn.cc (spawn_guts): Call refresh_cygheap before 
creating a new process to ensure that cygheap_max is up-to-date.")
Reviewed-by: Corinna Vinschen <cori...@vinschen.de>
Signed-off-by: Takashi Yano <takashi.y...@nifty.ne.jp>
---
 winsup/cygwin/spawn.cc | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index cb58b6eed..7f2f5a8aa 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -542,7 +542,6 @@ child_info_spawn::worker (const char *prog_arg, const char 
*const *argv,
        ::cygheap->ctty ? ::cygheap->ctty->tc_getpgid () : 0;
       if (!iscygwin () && ctty_pgid && ctty_pgid != myself->pgid)
        c_flags |= CREATE_NEW_PROCESS_GROUP;
-      refresh_cygheap ();
 
       if (mode == _P_DETACH)
        /* all set */;
@@ -611,6 +610,8 @@ child_info_spawn::worker (const char *prog_arg, const char 
*const *argv,
 
       cygpid = (mode != _P_OVERLAY) ? create_cygwin_pid () : myself->pid;
 
+      cygheap->lock ();
+      refresh_cygheap ();
       wchar_t wcmd[(size_t) cmd];
       if (!::cygheap->user.issetuid ()
          || (::cygheap->user.saved_uid == ::cygheap->user.real_uid
@@ -728,6 +729,7 @@ child_info_spawn::worker (const char *prog_arg, const char 
*const *argv,
            ::cygheap->user.reimpersonate ();
 
          res = -1;
+         cygheap->unlock ();
          __leave;
        }
 
@@ -764,8 +766,6 @@ child_info_spawn::worker (const char *prog_arg, const char 
*const *argv,
          NtClose (old_winpid_hdl);
          real_path.get_wide_win32_path (myself->progname); // FIXME: race?
          sigproc_printf ("new process name %W", myself->progname);
-         if (!iscygwin ())
-           close_all_files ();
        }
       else
        {
@@ -781,6 +781,7 @@ child_info_spawn::worker (const char *prog_arg, const char 
*const *argv,
              if (get_errno () != ENOMEM)
                set_errno (EAGAIN);
              res = -1;
+             cygheap->unlock ();
              __leave;
            }
          child->dwProcessId = pi.dwProcessId;
@@ -816,6 +817,7 @@ child_info_spawn::worker (const char *prog_arg, const char 
*const *argv,
              CloseHandle (pi.hProcess);
              ForceCloseHandle (pi.hThread);
              res = -1;
+             cygheap->unlock ();
              __leave;
            }
        }
@@ -844,6 +846,7 @@ child_info_spawn::worker (const char *prog_arg, const char 
*const *argv,
        /* Just mark a non-cygwin process as 'synced'.  We will still eventually
           wait for it to exit in maybe_set_exit_code_from_windows(). */
        synced = iscygwin () ? sync (pi.dwProcessId, pi.hProcess, INFINITE) : 
true;
+      cygheap->unlock ();
 
       switch (mode)
        {
@@ -860,8 +863,7 @@ child_info_spawn::worker (const char *prog_arg, const char 
*const *argv,
            }
          else
            {
-             if (iscygwin ())
-               close_all_files (true);
+             close_all_files (iscygwin ());
              if (!my_wr_proc_pipe
                  && WaitForSingleObject (pi.hProcess, 0) == WAIT_TIMEOUT)
                wait_for_myself ();
-- 
2.45.1