Files
hermes-agent/tools/environments/local_gitbash_probe.py
kshitijk4poor 99e1c16868 test(tools): pin the Git Bash probe's detached stdin in the existing probe test
The new standalone test file duplicated TestGitBashExternalProgramProbe's
harness; one assertion on the recorded kwargs covers the #78820 contract.
The sibling ASLR-probe assertion is dropped (unchanged code, already green
on main). Comment trimmed to the WHY.
2026-09-08 02:26:39 +05:30

106 lines
4.8 KiB
Python

"""Git Bash health probe + Mandatory-ASLR diagnostics (Windows), used by
``local._find_bash`` to pick a bash.exe that can actually launch MSYS children
and to build the targeted remediation when none can."""
import logging
import ntpath
import platform
import shutil
import subprocess
from hermes_cli._subprocess_compat import windows_hide_flags
_IS_WINDOWS = platform.system() == "Windows"
# Same logger as the origin module so log routing is unchanged.
logger = logging.getLogger("tools.environments.local")
_bash_starts_cache: dict[str, bool] = {}
_bash_probe_details_cache: dict[str, str] = {}
_mandatory_aslr_enabled_cache: "bool | None" = None
# External ``true`` and ``cat`` are intentional: a builtin-only ``exit 0`` probe
# misses Git-for-Windows fork/spawn failures under system-wide Mandatory ASLR.
_BASH_EXTERNAL_PROGRAM_PROBE = "/usr/bin/true; /usr/bin/cat --version >/dev/null"
_MSYS_SPAWN_FAILURE_MARKERS = ("dofork:", "child_copy:", "0xc0000142", "0xc0000005")
def _looks_like_msys_spawn_failure(details: str) -> bool:
"""Match Git-for-Windows child-launch failures associated with ASLR."""
lowered = details.lower()
return any(marker in lowered for marker in _MSYS_SPAWN_FAILURE_MARKERS)
def _mandatory_aslr_enabled() -> "bool | None":
"""Return Windows' system-wide ForceRelocateImages state when available."""
global _mandatory_aslr_enabled_cache
if _mandatory_aslr_enabled_cache is not None:
return _mandatory_aslr_enabled_cache
cmd = [shutil.which("powershell.exe") or "powershell.exe", "-NoProfile", "-NonInteractive",
"-Command", "(Get-ProcessMitigation -System).Aslr.ForceRelocateImages.ToString()"]
try:
result = subprocess.run(cmd, capture_output=True, text=True, encoding="utf-8",
errors="replace", timeout=10, creationflags=windows_hide_flags(), stdin=subprocess.DEVNULL)
except Exception as exc:
logger.debug("Could not query Windows Mandatory ASLR state: %s", exc)
return None
if result.returncode != 0:
return None
value = (result.stdout or "").strip().upper()
_mandatory_aslr_enabled_cache = {"ON": True, "OFF": False, "NOTSET": False}.get(value)
return _mandatory_aslr_enabled_cache
def _git_root_from_bash(bash: str) -> str:
"""Resolve Git's root from either <root>/bin or <root>/usr/bin bash."""
bin_dir = ntpath.dirname(ntpath.normpath(bash))
if ntpath.basename(bin_dir).lower() != "bin":
return ntpath.dirname(bin_dir)
parent = ntpath.dirname(bin_dir)
return ntpath.dirname(parent) if ntpath.basename(parent).lower() == "usr" else parent
def _git_bash_aslr_help(bash: str, details: str = "") -> str:
"""Build the targeted per-program Mandatory-ASLR remediation."""
escaped_root = _git_root_from_bash(bash).replace("'", "''")
detail_line = f"\nGit Bash probe output: {details[:500]}" if details else ""
return (
f"Git Bash at {bash} cannot launch required MSYS child processes while "
"Windows Mandatory ASLR (ForceRelocateImages) is enabled, or its output "
f"matches that Git-for-Windows failure class.{detail_line}\n"
"Reinstalling Git will not change the Windows mitigation policy. Open "
"PowerShell as Administrator and run:\n"
f"$gitRoot = '{escaped_root}'\n"
'Get-Item "$gitRoot\\bin\\bash.exe", "$gitRoot\\usr\\bin\\*.exe" '
"-ErrorAction SilentlyContinue | ForEach-Object { "
"Set-ProcessMitigation -Name $_.FullName -Disable ForceRelocateImages }\n"
"Then restart Hermes. If the override is blocked or later re-applied, "
"ask your Windows administrator to allow this per-program exception."
)
def _bash_starts(bash: str) -> bool:
"""True if *bash* can launch external MSYS programs (cached per path).
``--noprofile --norc`` so a broken login post-install (``Directory
\\drivers\\etc``) does not falsely condemn an otherwise usable bash."""
if bash in _bash_starts_cache:
return _bash_starts_cache[bash]
try:
result = subprocess.run(
[bash, "--noprofile", "--norc", "-c", _BASH_EXTERNAL_PROGRAM_PROBE],
capture_output=True, text=True, encoding="utf-8", errors="replace",
timeout=15, creationflags=windows_hide_flags() if _IS_WINDOWS else 0,
stdin=subprocess.DEVNULL) # #78820: never hand the TUI gateway's stdin pipe to MSYS bash
ok = result.returncode == 0
if not ok:
combined = f"{result.stdout or ''}{result.stderr or ''}".strip()
_bash_probe_details_cache[bash] = combined[:2000]
logger.debug("bash probe failed for %s: %s", bash, combined[:200])
except Exception as exc:
_bash_probe_details_cache[bash] = str(exc)[:2000]
logger.debug("bash probe error for %s: %s", bash, exc)
ok = False
_bash_starts_cache[bash] = ok
return ok