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Date: Sun, 23 May 1999 23:37:57 +0400
From: Egor Duda <deo AT logos-m DOT ru>
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Reply-To: Egor Duda <deo AT logos-m DOT ru>
Organization: DEO
Message-ID: <15984.990523@logos-m.ru>
To: cygwin-developers <cygwin-developers AT sourceware DOT cygnus DOT com>
Subject: bash fails to handle background jobs
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Hi!

  Trying to run background jobs in bash causes it to exit. According
to traces, is seems that when background job exits, pty-master writes
dummy data to tty_slave:

fhandler_pty_master::accept_input ()
{
  DWORD written;
  DWORD n = eat_readahead (-1);   // returns 0;
  const char dummy[1] = {'X'};
  const char *buf;

  if (n != 0)
    buf = rabuf;
  else
    {
      n = 1;
      buf = dummy;
    }
  termios_printf ("about to write %d chars to slave", n);
  if (!WriteFile (get_output_handle (), buf, n, &written, NULL))
      return -1;
  return buf == dummy ? 0 : (int)n;
    /* returns 0, but still puts 1 byte of data into the pipe between
     * master and slave. Later on, peek_pipe () detects this data and
     * marks slave as "ready to read". Slave tries to read, retrives 0
     * bytes (as long tc->read_retval is set to 0 in
     * fhandler_termios.cc:191) and interprets it as EOF. bash sees
     * EOF and exits.
     */
}

Applying following patch seems to fix a problem, but it really looks
like quick'n'dirty workaround to me. i'm not so good with tty stuff,
so i hope someone will find a way to fix this problem properly.

Index: fhandler_tty.cc
===================================================================
RCS file: /usr/local/src/cvs/cygnus/cygwin/winsup/fhandler_tty.cc,v
retrieving revision 1.1.1.1
diff -u -2 -r1.1.1.1 fhandler_tty.cc
--- fhandler_tty.cc 1999/04/10 14:55:01 1.1.1.1
+++ fhandler_tty.cc 1999/05/23 19:25:05
@@ -136,5 +136,5 @@
   else
     {
-      n = 1;
+      n = 0;
       buf = dummy;
     }


Egor.            mailto:deo AT logos-m DOT ru ICQ 5165414 FidoNet 2:5020/496.19