Fixes issue7208 - getpass would still allow the password to be echoed on

Solaris due to not flushing the input buffer.

This change also incorporates some additional getpass implementation
suggestions for security based on an analysis of getpass.c linked to from the
issue.

Lib/getpass.py

@@ -62,12 +62,16 @@ def unix_getpass(prompt='Password: ', stream=None):
         try:
             old = termios.tcgetattr(fd)     # a copy to save
             new = old[:]
-            new[3] &= ~termios.ECHO  # 3 == 'lflags'
+            new[3] &= ~(termios.ECHO|termios.ISIG)  # 3 == 'lflags'
+            tcsetattr_flags = termios.TCSAFLUSH
+            if hasattr(termios, 'TCSASOFT'):
+                tcsetattr_flags |= termios.TCSASOFT
             try:
-                termios.tcsetattr(fd, termios.TCSADRAIN, new)
+                termios.tcsetattr(fd, tcsetattr_flags, new)
                 passwd = _raw_input(prompt, stream, input=input)
             finally:
-                termios.tcsetattr(fd, termios.TCSADRAIN, old)
+                termios.tcsetattr(fd, tcsetattr_flags, old)
+                stream.flush()  # issue7208
         except termios.error, e:
             if passwd is not None:
                 # _raw_input succeeded.  The final tcsetattr failed.  Reraise
@@ -125,6 +129,7 @@ def _raw_input(prompt="", stream=None, input=None):
     if prompt:
         stream.write(prompt)
         stream.flush()
+    # NOTE: The Python C API calls flockfile() (and unlock) during readline.
     line = input.readline()
     if not line:
         raise EOFError