Don't raise SIGTTIN from poll/select

SIGTTIN should be raised when read() is made on a tty in a backgrounded
process, but not when it's tested with poll()/select().

I guess poll()/select() does need to call bg_check(), in order to detect the
error conditions that notices (that is, if bg_check() returns bg_eof or
bg_error, then fd is ready as an error condition exists) so add an optional
parameter to fhandler_base::bg_select() to indicate that signals aren't
desired.

See https://cygwin.com/ml/cygwin-developers/2016-07/msg00004.html

1 files changed, 2 insertions, 2 deletions

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 9f9d9bd8f..3321523ef 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -427,7 +427,7 @@ public:
   {
     return dev ().native ();
   }
-  virtual bg_check_types bg_check (int) {return bg_ok;}
+  virtual bg_check_types bg_check (int, bool = false) {return bg_ok;}
   void clear_readahead ()
   {
     raixput = raixget = ralen = rabuflen = 0;
@@ -1233,7 +1233,7 @@ class fhandler_termios: public fhandler_base
   void sigflush ();
   int tcgetpgrp ();
   int tcsetpgrp (int pid);
-  bg_check_types bg_check (int sig);
+  bg_check_types bg_check (int sig, bool dontsignal = false);
   virtual DWORD __acquire_output_mutex (const char *fn, int ln, DWORD ms) {return 1;}
   virtual void __release_output_mutex (const char *fn, int ln) {}
   void echo_erase (int force = 0);