gh-128636: Fix crash in PyREPL when os.environ is overwritten with an invalid value for mac

Lib/_colorize.py

@@ -286,25 +286,30 @@ def decolor(text: str) -> str:
     return text
 
 
-def can_colorize(*, file: IO[str] | IO[bytes] | None = None, already_colorize: bool = False) -> bool:
-    if already_colorize:
-        return True
+def can_colorize(*, file: IO[str] | IO[bytes] | None = None) -> bool:
+
+    def _safe_getenv(k: str, fallback: str | None = None) -> str | None:
+        """Exception-safe environment retrieval. See gh-128636."""
+        try:
+            return os.environ.get(k, fallback)
+        except Exception:
+            return fallback
 
     if file is None:
         file = sys.stdout
 
     if not sys.flags.ignore_environment:
-        if os.environ.get("PYTHON_COLORS") == "0":
+        if _safe_getenv("PYTHON_COLORS") == "0":
             return False
-        if os.environ.get("PYTHON_COLORS") == "1":
+        if _safe_getenv("PYTHON_COLORS") == "1":
             return True
-    if os.environ.get("NO_COLOR"):
+    if _safe_getenv("NO_COLOR"):
         return False
     if not COLORIZE:
         return False
-    if os.environ.get("FORCE_COLOR"):
+    if _safe_getenv("FORCE_COLOR"):
         return True
-    if os.environ.get("TERM") == "dumb":
+    if _safe_getenv("TERM") == "dumb":
         return False
 
     if not hasattr(file, "fileno"):
@@ -334,7 +339,6 @@ def get_theme(
     tty_file: IO[str] | IO[bytes] | None = None,
     force_color: bool = False,
     force_no_color: bool = False,
-    already_colorize: bool = False,
 ) -> Theme:
     """Returns the currently set theme, potentially in a zero-color variant.
 
@@ -349,7 +353,7 @@ def get_theme(
     on Windows) can also change in the course of the application life cycle.
     """
     if force_color or (not force_no_color and
-                       can_colorize(file=tty_file, already_colorize=already_colorize)):
+                       can_colorize(file=tty_file)):
         return _theme
     return theme_no_color
 

Lib/_pyrepl/reader.py

@@ -343,7 +343,7 @@ def calc_screen(self) -> list[str]:
                 screeninfo.append((0, []))
             pos -= line_len + 1
             prompt, prompt_len = self.process_prompt(prompt)
-            chars, char_widths = disp_str(line, colors, offset, already_colorize=self.can_colorize)
+            chars, char_widths = disp_str(line, colors, offset)
             wrapcount = (sum(char_widths) + prompt_len) // self.console.width
             if wrapcount == 0 or not char_widths:
                 offset += line_len + 1  # Takes all of the line plus the newline
@@ -491,7 +491,7 @@ def get_prompt(self, lineno: int, cursor_on_line: bool) -> str:
             prompt = self.ps1
 
         if self.can_colorize:
-            t = THEME(already_colorize=self.can_colorize)
+            t = THEME()
             prompt = f"{t.prompt}{prompt}{t.reset}"
         return prompt
 

Lib/_pyrepl/unix_console.py

@@ -159,7 +159,7 @@ def __init__(
         self.pollob.register(self.input_fd, select.POLLIN)
         self.terminfo = terminfo.TermInfo(term or None)
         self.term = term
-        self.is_mac = (
+        self.is_apple_terminal = (
             platform.system() == "Darwin"
             and os.getenv("TERM_PROGRAM") == "Apple_Terminal"
         )
@@ -343,7 +343,7 @@ def prepare(self):
         tcsetattr(self.input_fd, termios.TCSADRAIN, raw)
 
         # In macOS terminal we need to deactivate line wrap via ANSI escape code
-        if self.is_mac:
+        if self.is_apple_terminal:
             os.write(self.output_fd, b"\033[?7l")
 
         self.screen = []
@@ -374,7 +374,7 @@ def restore(self):
         self.flushoutput()
         tcsetattr(self.input_fd, termios.TCSADRAIN, self.__svtermstate)
 
-        if self.is_mac:
+        if self.is_apple_terminal:
             os.write(self.output_fd, b"\033[?7h")
 
         if hasattr(self, "old_sigwinch"):

Lib/_pyrepl/utils.py

@@ -266,7 +266,6 @@ def disp_str(
     colors: list[ColorSpan] | None = None,
     start_index: int = 0,
     force_color: bool = False,
-    already_colorize: bool = False,
 ) -> tuple[CharBuffer, CharWidths]:
     r"""Decompose the input buffer into a printable variant with applied colors.
 
@@ -307,7 +306,7 @@ def disp_str(
         # move past irrelevant spans
         colors.pop(0)
 
-    theme = THEME(force_color=force_color, already_colorize=already_colorize)
+    theme = THEME(force_color=force_color)
     pre_color = ""
     post_color = ""
     if colors and colors[0].span.start < start_index:

Lib/test/support/__init__.py

@@ -2898,7 +2898,7 @@ def force_color(color: bool):
     from .os_helper import EnvironmentVarGuard
 
     with (
-        swap_attr(_colorize, "can_colorize", lambda *, file=None, already_colorize=False: color),
+        swap_attr(_colorize, "can_colorize", lambda *, file=None: color),
         EnvironmentVarGuard() as env,
     ):
         env.unset("FORCE_COLOR", "NO_COLOR", "PYTHON_COLORS")