Hermes-agent

hermes_cli/secret_prompt.py

@@ -0,0 +1,126 @@
+"""Secret input prompts with masked typing feedback."""
+
+from __future__ import annotations
+
+import getpass
+import os
+import sys
+from collections.abc import Callable
+
+
+_BACKSPACE_CHARS = {"\b", "\x7f"}
+_ENTER_CHARS = {"\r", "\n"}
+_EOF_CHARS = {"\x04", "\x1a"}
+
+
+def _collect_masked_input(
+    read_char: Callable[[], str],
+    write: Callable[[str], object],
+    prompt: str,
+    *,
+    mask: str = "*",
+) -> str:
+    """Read one secret line while writing a mask character per typed char."""
+    value: list[str] = []
+    write(prompt)
+
+    while True:
+        ch = read_char()
+        if ch == "":
+            write("\n")
+            raise EOFError
+        if ch in _ENTER_CHARS:
+            write("\n")
+            return "".join(value)
+        if ch == "\x03":
+            write("\n")
+            raise KeyboardInterrupt
+        if ch in _EOF_CHARS:
+            write("\n")
+            raise EOFError
+        if ch in _BACKSPACE_CHARS:
+            if value:
+                value.pop()
+                write("\b \b")
+            continue
+        if ch == "\x1b":
+            # Ignore escape itself. Terminals commonly send escape-prefixed
+            # navigation/delete sequences; they should not become secret text.
+            continue
+
+        value.append(ch)
+        if mask:
+            write(mask)
+
+
+def masked_secret_prompt(prompt: str, *, mask: str = "*") -> str:
+    """Prompt for a secret while showing masked typing feedback.
+
+    Falls back to ``getpass.getpass`` when stdin/stdout are not interactive or
+    when raw terminal handling is unavailable.
+    """
+    stdin = sys.stdin
+    stdout = sys.stdout
+
+    if not _stream_is_tty(stdin) or not _stream_is_tty(stdout):
+        return getpass.getpass(prompt)
+
+    if os.name == "nt":
+        try:
+            return _masked_secret_prompt_windows(prompt, mask=mask)
+        except (KeyboardInterrupt, EOFError):
+            raise
+        except Exception:
+            return getpass.getpass(prompt)
+
+    try:
+        return _masked_secret_prompt_posix(prompt, mask=mask)
+    except (KeyboardInterrupt, EOFError):
+        raise
+    except Exception:
+        return getpass.getpass(prompt)
+
+
+def _stream_is_tty(stream) -> bool:
+    try:
+        return bool(stream.isatty())
+    except Exception:
+        return False
+
+
+def _masked_secret_prompt_windows(prompt: str, *, mask: str) -> str:
+    import msvcrt
+
+    def read_char() -> str:
+        ch = msvcrt.getwch()
+        if ch in {"\x00", "\xe0"}:
+            msvcrt.getwch()
+            return "\x1b"
+        return ch
+
+    def write(text: str) -> None:
+        sys.stdout.write(text)
+        sys.stdout.flush()
+
+    return _collect_masked_input(read_char, write, prompt, mask=mask)
+
+
+def _masked_secret_prompt_posix(prompt: str, *, mask: str) -> str:
+    import termios
+    import tty
+
+    fd = sys.stdin.fileno()
+    old_attrs = termios.tcgetattr(fd)
+
+    def read_char() -> str:
+        return sys.stdin.read(1)
+
+    def write(text: str) -> None:
+        sys.stdout.write(text)
+        sys.stdout.flush()
+
+    try:
+        tty.setraw(fd)
+        return _collect_masked_input(read_char, write, prompt, mask=mask)
+    finally:
+        termios.tcsetattr(fd, termios.TCSADRAIN, old_attrs)