Fix: termios.error: (22, 'Invalid argument') during `become` on Solaris/Illumos/SmartOS (#1089)

This fixes compatibility with Solaris/Illumos/SmartOS, addressing an issue that shows up most frequently with become. The issue was mostly due to differences in how the TTY driver is handled and the pty driver not supporting echo on both sides of the pipe (as designed, from a Solaris point of view).

Fixes #950

Co-authored-by: Alex Willmer <alex@moreati.org.uk>

docs/changelog.rst

@@ -21,6 +21,7 @@ To avail of fixes in an unreleased version, please download a ZIP file
 Unreleased
 ----------
 
+* :gh:issue:`950` Fix Solaris/Illumos/SmartOS compatibility with become
 * :gh:issue:`1087` Fix :exc:`mitogen.core.StreamError` when Ansible template
   module is called with a ``dest:`` filename that has an extension
 * :gh:issue:`1110` Fix :exc:`mitogen.core.StreamError` when Ansible copy

mitogen/parent.py

@@ -147,6 +147,8 @@ LINUX_TIOCGPTN = _ioctl_cast(2147767344)
 LINUX_TIOCSPTLCK = _ioctl_cast(1074025521)
 
 IS_LINUX = os.uname()[0] == 'Linux'
+IS_SOLARIS = os.uname()[0] == 'SunOS'
+
 
 SIGNAL_BY_NUM = dict(
     (getattr(signal, name), name)
@@ -411,7 +413,7 @@ def _acquire_controlling_tty():
         # On Linux, the controlling tty becomes the first tty opened by a
         # process lacking any prior tty.
         os.close(os.open(os.ttyname(2), os.O_RDWR))
-    if hasattr(termios, 'TIOCSCTTY') and not mitogen.core.IS_WSL:
+    if hasattr(termios, 'TIOCSCTTY') and not mitogen.core.IS_WSL and not IS_SOLARIS:
         # #550: prehistoric WSL does not like TIOCSCTTY.
         # On BSD an explicit ioctl is required. For some inexplicable reason,
         # Python 2.6 on Travis also requires it.
@@ -479,6 +481,7 @@ def openpty():
 
     master_fp = os.fdopen(master_fd, 'r+b', 0)
     slave_fp = os.fdopen(slave_fd, 'r+b', 0)
+    if not IS_SOLARIS:
         disable_echo(master_fd)
     disable_echo(slave_fd)
     mitogen.core.set_block(slave_fd)