Fix enabling of windows color terminal processing (#25529)

This was broken in #25502 and we only have limited testing of this
features. Specifically we only test that the ANSI codes are generated,
not that they are successfully processed.

The change here is not only to check for
ENABLE_VIRTUAL_TERMINAL_PROCESSING mode but to actually set this mode.

Replaces #25525

Author: sbc100

tools/colored_logger.py

@@ -67,14 +67,16 @@ def ansi_color_available():
   kernel32 = ctypes.windll.kernel32
   stdout_handle = kernel32.GetStdHandle(STD_OUTPUT_HANDLE)
 
-  # Get the current console mode
   console_mode = ctypes.c_uint()
-  if not kernel32.GetConsoleMode(stdout_handle, ctypes.byref(console_mode)):
-    # Handle error if GetConsoleMode fails
+  # Attempt to enable ANSI color processing (ENABLE_VIRTUAL_TERMINAL_PROCESSING).
+  # Assume that failure of either GetConsoleMode or SetConsoleMode means that stdout
+  # is not attached to a terminal or that the terminal does not support this mode.
+  if kernel32.GetConsoleMode(stdout_handle, ctypes.byref(console_mode)) == 0:
+    return False
+  if kernel32.SetConsoleMode(stdout_handle, console_mode.value | ENABLE_VIRTUAL_TERMINAL_PROCESSING) == 0:
     return False
 
-  # Check if the flag is set in the current console mode
-  return (console_mode.value & ENABLE_VIRTUAL_TERMINAL_PROCESSING) != 0
+  return True
 
 
 def add_coloring_to_emit_ansi(fn):
@@ -101,13 +103,15 @@ def new(*args):
 
 def enable(force=False):
   global color_enabled
-  if force or ansi_color_available():
-    logging.StreamHandler.emit = add_coloring_to_emit_ansi(logging.StreamHandler.emit)
-    color_enabled = True
+  if not color_enabled:
+    if ansi_color_available() or force:
+      logging.StreamHandler.emit = add_coloring_to_emit_ansi(logging.StreamHandler.emit)
+      color_enabled = True
 
 
 def disable():
   global color_enabled
-  if hasattr(logging.StreamHandler.emit, 'orig_func'):
-    logging.StreamHandler.emit = logging.StreamHandler.emit.orig_func
-  color_enabled = False
+  if color_enabled:
+    if hasattr(logging.StreamHandler.emit, 'orig_func'):
+      logging.StreamHandler.emit = logging.StreamHandler.emit.orig_func
+    color_enabled = False