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esphome/esphome/platformio/pch.py.script
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import hashlib
import os
from pathlib import Path
import posixpath
import re
import shlex
import stat
import subprocess
import traceback
# pylint: disable=E0602
Import("env") # noqa: F821
_projenv_error = None
try:
Import("projenv") # noqa: F821
except Exception as err: # noqa: BLE001 -- not exported under -t nobuild
projenv = None
_projenv_error = err
# Precompile the src force-includes plus defines.h and force-include the
# result into C++ src compiles only; their preprocessed output is unchanged.
# Registration is gated host-side (pch_enabled()). Keep the closure, ccache
# values, probe flow, stamp flow, and env-knob spellings in sync with
# build_helpers/pch.py.
# Compiler failures that clear on their own must not latch the .failed marker
_TRANSIENT_ERRORS = ("No space left", "Cannot allocate", "Resource temporarily")
# Keep in sync with helpers.TRUTHY_ENV_STRINGS / FALSY_ENV_STRINGS
_TRUTHY = ("1", "true", "yes", "on", "enable")
_FALSY = ("", "0", "false", "no", "off", "disable")
_STRICT_RAW = os.environ.get("ESPHOME_PCH_STRICT")
_STRICT_VALUE = (_STRICT_RAW or "").strip().lower()
_STRICT = _STRICT_VALUE in _TRUTHY
if _STRICT_RAW is not None and _STRICT_VALUE not in _TRUTHY + _FALSY:
# A typo must not silently turn the gate into a no-op
raise RuntimeError(f"Unrecognized ESPHOME_PCH_STRICT={_STRICT_RAW!r}; use 1 or 0")
_INCLUDE_RE = re.compile(rb'^\s*#\s*include\s+["<]([^">]+)[">]', re.MULTILINE)
_CORE_HEADER = "esphome/core/defines.h"
def _raise_walk_error(err: OSError) -> None:
raise err
def _resolves_dir(path: Path) -> bool:
"""False when missing; other stat failures propagate."""
try:
return stat.S_ISDIR(path.stat().st_mode)
except (FileNotFoundError, NotADirectoryError):
return False
def _resolves(path: Path) -> bool:
"""False when missing; other stat failures propagate (identity unknown)."""
try:
return stat.S_ISREG(path.stat().st_mode)
except (FileNotFoundError, NotADirectoryError):
return False
def _include_closure(src_dir: Path, roots: list) -> dict:
"""Quoted-include closure: src-relative name -> contents (mirror of
build_helpers/pch.py)."""
seen = {}
stack = [(name, "") for name in roots]
while stack:
name, from_dir = stack.pop()
for candidate in (f"{from_dir}/{name}" if from_dir else name, name):
rel = posixpath.normpath(candidate)
if not rel.startswith("..") and _resolves(src_dir / rel):
break
else:
continue
if rel in seen:
continue
try:
data = (src_dir / rel).read_bytes()
except OSError as err:
# A marker would truncate the transitive walk; fail closed
print(f"ESPHome: could not read {rel} for the pch checksum: {err}")
raise
seen[rel] = data
parent = posixpath.dirname(rel)
stack.extend(
(inc.decode(errors="surrogateescape"), parent)
for inc in _INCLUDE_RE.findall(data)
)
return seen
def _shell_arg(element) -> str | None:
"""One compiler argv from one SCons element, matching the real spawn:
spaced elements pass whole, the rest get one shell unquote (skipped on
Windows, where shlex would eat path backslashes)."""
arg = str(element)
if " " in arg or os.name == "nt":
return arg.replace('\\"', '"')
if not arg.strip():
return arg
try:
tokens = shlex.split(arg)
except ValueError as err:
print(f"ESPHome: could not lex flag {arg!r} for the pch: {err}")
return None
if len(tokens) != 1:
# A flag the model cannot reproduce would diverge the .gch's flags
print(f"ESPHome: cannot model flag {arg!r} for the pch")
return None
return tokens[0]
def _compile_gch(cxx, flags, header: Path, gch: Path, proj_dir: Path):
"""Compile the .gch, then probe that the toolchain can load it back
(GCC 10 on macOS arm64 rejects its own per-process). Returns an error
string or None; OSError propagates as transient."""
result = subprocess.run( # noqa: PLW1510
[cxx, "-x", "c++-header", *flags, "-c", str(header), "-o", str(gch)],
cwd=proj_dir,
# C locale keeps diagnostics matchable by _TRANSIENT_ERRORS
env={**os.environ, "LC_ALL": "C"},
capture_output=True,
text=True,
)
if result.returncode < 0:
# Signal-killed (OOM, ^C): route to the transient no-marker path
raise OSError(f"compiler killed by signal {-result.returncode}")
if result.returncode != 0:
return result.stderr
return _probe_gch(cxx, flags, header, proj_dir)
def _probe_run(cxx, flags, extra, proj_dir: Path):
probe = subprocess.run( # noqa: PLW1510
[cxx, *flags, *extra, "-fsyntax-only", "-x", "c++", "-"],
cwd=proj_dir,
env={**os.environ, "LC_ALL": "C"},
input="",
capture_output=True,
text=True,
)
if probe.returncode < 0:
raise OSError(f"probe killed by signal {-probe.returncode}")
return probe
def _probe_gch(cxx, flags, header: Path, proj_dir: Path):
"""Load-check an existing .gch; error string or None. Rejection must
be a nonzero exit (keep in sync with pch_probe_args); a baseline run
without the pch keeps environmental failures from being blamed on it."""
# -MF is only legal alongside a dependency flag; pass it solely to
# redirect a depfile that -MD/-MMD in the flags would otherwise write
dep_redirect = (
["-MF", os.devnull]
if any(f in ("-MD", "-MMD", "-M", "-MM") for f in flags)
else []
)
probe = _probe_run(
cxx,
flags,
[*dep_redirect, "-Winvalid-pch", "-Werror=invalid-pch", "-include", str(header)],
proj_dir,
)
if probe.returncode == 0:
return None
baseline = _probe_run(cxx, flags, dep_redirect, proj_dir)
if baseline.returncode != 0:
# Deterministic and latchable; the transient filter at the caller
# keeps resource exhaustion from latching
return f"probe cannot run at all: {baseline.stderr.strip()[:200]}"
return f"toolchain cannot load the pch: {probe.stderr.strip()}"
def _read_stamp(path: Path) -> str:
"""A corrupt sidecar must read as stale, not kill the pch forever."""
try:
return path.read_text(encoding="utf-8").strip()
except (OSError, UnicodeDecodeError):
return ""
def _setup_pch() -> bool | None:
if projenv is None:
print(f"ESPHome: projenv unavailable ({_projenv_error}); skipping pch")
try:
from SCons.Script import COMMAND_LINE_TARGETS
except ImportError:
# No SCons is an anomaly under PlatformIO: the unknown state
# must not read as success (strict decides fatality at the gate)
return False
# Expected under -t nobuild (nothing compiles); a missing
# projenv on a real compile must not pass strict
return "nobuild" in [str(t) for t in COMMAND_LINE_TARGETS]
# Project root: SCons compiles run here, so the relative -include
# resolves; an absolute path would break cross-device ccache sharing.
proj_dir = Path(env.subst("$PROJECT_DIR")) # noqa: F821
src_dir = Path(env.subst("$PROJECT_SRC_DIR")) # noqa: F821
header = proj_dir / "esphome_pch.h"
gch = Path(f"{header}.gch")
sum_path = Path(f"{gch}.sum")
cxx = projenv.subst("$CXX") # noqa: F821
# The header holds the -include entries itself, so the .gch compile must
# not see them; consumers keep theirs, which the .gch then satisfies.
flags = []
include_headers = []
raw_args = [
_shell_arg(element)
for element in projenv.subst_list("$CXXFLAGS $CCFLAGS $_CCCOMCOM")[0] # noqa: F821
]
if any(arg is None for arg in raw_args):
print("ESPHome: skipping precompiled header: unmodelable flag")
return
flag_it = iter(raw_args)
for tok in flag_it:
if tok == "-include":
include_headers.append(next(flag_it, ""))
elif tok.startswith("-include") and not tok.startswith("-include-"):
include_headers.append(tok[len("-include") :])
else:
flags.append(tok)
if any(not name for name in include_headers):
print("ESPHome: build_src_flags has a trailing -include; skipping pch")
return
# Fold only relative names resolving under src/: consumers keep their
# own -include entries, so folding an unguarded user header would
# include it twice; unfolded ones stay consumer-only.
try:
folded = [
name
for name in include_headers
if not Path(name).is_absolute() and _resolves(src_dir / name)
]
except OSError as err:
print(f"ESPHome: skipping precompiled header: {err}")
return
if unfolded := [n for n in include_headers if n not in folded]:
print(f"ESPHome: not precompiling non-src force-includes: {unfolded}")
content = "".join(f'#include "{name}"\n' for name in (*folded, _CORE_HEADER))
digest = hashlib.sha256()
digest.update(content.encode(errors="surrogateescape"))
digest.update(cxx.encode(errors="surrogateescape"))
# Mirror CCACHE_BASEDIR: strip the per-device build path so identical
# configs produce identical .sum files and share cache entries
flags_id = " ".join(flags)
if basedir := os.environ.get("CCACHE_BASEDIR"):
flags_id = flags_id.replace(basedir, "")
digest.update(flags_id.encode(errors="surrogateescape"))
# GCC never validates a .gch against its source headers, and PlatformIO
# package paths carry no version, so a package bump must invalidate here
platform = env.PioPlatform() # noqa: F821
for package in sorted(platform.packages):
try:
version = platform.get_package_version(package)
except KeyError:
# An unresolved manifest must not hash as a constant
if platform.get_package(package) is not None:
print(f"ESPHome: skipping precompiled header: no version for {package}")
return
version = None # absent optional package
except Exception as err: # noqa: BLE001
# No trustworthy package identity: a stale .gch could survive
print(f"ESPHome: skipping precompiled header: {err}")
return
digest.update(f"{package}={version}".encode())
digest.update(b"\0")
try:
closure = _include_closure(src_dir, [*folded, _CORE_HEADER])
except OSError as err:
print(f"ESPHome: skipping precompiled header: {err}")
return
for rel in sorted(closure):
digest.update(rel.encode(errors="surrogateescape"))
digest.update(closure[rel])
digest.update(b"\0")
# Project-local -I dirs (e.g. rp2's lwip_override) hold generated
# headers the src closure cannot see; hash them too
prev = ""
try:
for tok in flags:
inc = tok[2:] if tok.startswith("-I") and len(tok) > 2 else ""
if prev == "-I":
inc = tok
prev = tok
if not inc:
continue
inc_dir = Path(inc)
if not (
_resolves_dir(inc_dir)
and inc_dir.is_relative_to(proj_dir)
and not inc_dir.is_relative_to(src_dir)
# Library trees never enter the prefix closure; walking them
# would read every library file each build
and not inc_dir.is_relative_to(proj_dir / ".piolibdeps")
and not inc_dir.is_relative_to(proj_dir / ".pioenvs")
):
continue
local_headers = []
# os.walk with onerror: rglob would swallow unlistable subtrees
for root, _dirs, files in os.walk(inc_dir, onerror=_raise_walk_error):
local_headers.extend(
Path(root) / f
for f in files
if f.endswith((".h", ".hpp", ".hh", ".inc"))
)
for local in sorted(local_headers):
digest.update(str(local.relative_to(proj_dir)).encode())
digest.update(local.read_bytes())
digest.update(b"\0")
except OSError as err:
print(f"ESPHome: skipping precompiled header: {err}")
return
checksum = digest.hexdigest()
# The ccache .sum sidecar doubles as the freshness stamp
fresh = (
header.is_file()
and gch.is_file()
and sum_path.is_file()
and (_read_stamp(sum_path) == checksum)
)
if fresh and _STRICT:
# Rejection is per-process: strict re-proves a cached .gch loads
# (mirrors the pch_strict() re-probe in build_helpers/pch.py)
error = _probe_gch(cxx, flags, header, proj_dir)
if error is not None:
print(f"ESPHome: {error}")
gch.unlink(missing_ok=True)
sum_path.unlink(missing_ok=True)
return
if not fresh:
failed_marker = Path(f"{gch}.failed")
if _read_stamp(failed_marker) == checksum:
print(
"ESPHome: skipping precompiled header (previous attempt "
f"failed); delete {failed_marker.name} to retry"
)
return
header.write_text(content, encoding="utf-8")
try:
error = _compile_gch(cxx, flags, header, gch, proj_dir)
except OSError as err:
# Transient spawn/IO failure: no marker, retry next build
print(f"ESPHome: precompiled header compile did not run: {err}")
gch.unlink(missing_ok=True)
sum_path.unlink(missing_ok=True)
return
if error is not None:
print("ESPHome: precompiled header failed; compiling without it")
print(error)
gch.unlink(missing_ok=True)
sum_path.unlink(missing_ok=True)
if any(m in error for m in _TRANSIENT_ERRORS):
# Resource exhaustion clears on its own; retry next build
return
# Skip retries until a flag/header/platform change alters the checksum
failed_marker.write_text(checksum + "\n", encoding="utf-8")
return
failed_marker.unlink(missing_ok=True)
sum_path.write_text(checksum + "\n", encoding="utf-8")
# Computed first so the flags and env land together: a raise between
# them would leave a pch-consuming build without its ccache settings.
# projenv["ENV"] aliases os.environ, so these reach all TUs; only
# time_macros affects non-pch TUs. User values win.
ccache_updates = {
key: value
for key, value in (
("CCACHE_SLOPPINESS", "pch_defines,time_macros"),
("CCACHE_PCH_EXTSUM", "true"),
)
if key not in os.environ
}
sloppiness = os.environ.get("CCACHE_SLOPPINESS")
if sloppiness is not None:
tokens = {tok.strip() for tok in sloppiness.split(",")}
missing = [t for t in ("pch_defines", "time_macros") if t not in tokens]
if missing:
# Without these ccache declines every pch-consuming compile
ccache_updates["CCACHE_SLOPPINESS"] = ",".join((sloppiness, *missing))
print(f"ESPHome: adding {','.join(missing)} to CCACHE_SLOPPINESS for the pch")
extsum = os.environ.get("CCACHE_PCH_EXTSUM")
if extsum is not None and extsum.strip().lower() not in ("1", "true", "yes", "on"):
# ccache then hashes the non-reproducible .gch bytes: permanent misses
print(f"ESPHome: CCACHE_PCH_EXTSUM={extsum} disables pch caching")
# Prepended: GCC only uses a .gch while no other tokens precede it.
# The relative name also reaches "pio run -t idedata" output.
# -Wno-error: the per-process probe can pass while a later cc1plus
# rejects the .gch; that must stay a warning under user -Werror.
projenv.Prepend( # noqa: F821
CXXFLAGS=[
"-Winvalid-pch",
# Strict inverts: a per-process consumer rejection reds the build
"-Werror=invalid-pch" if _STRICT else "-Wno-error=invalid-pch",
"-include",
header.name,
]
)
projenv["ENV"].update(ccache_updates) # noqa: F821
print("ESPHome: Compiling with precompiled header")
return True
try:
_used = _setup_pch()
except Exception: # noqa: BLE001 -- a speedup must never break the build
if _STRICT:
raise
print("ESPHome: pch internal error; compiling without it")
traceback.print_exc()
else:
if _STRICT and not _used:
raise RuntimeError("ESPHOME_PCH_STRICT: precompiled header was not used")