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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at
import buildconfig
import shutil
import subprocess
import os
import sys
def relativize(path, base=None):
# For absolute path in Unix builds, we need relative paths because
# Windows programs run via Wine don't like these Unix absolute paths
# (they look like command line arguments).
if path.startswith("/"):
return os.path.relpath(path, base)
# For Windows absolute paths, we can just use the unmodified path.
# And if the path starts with '-', it's a command line argument.
if os.path.isabs(path) or path.startswith("-"):
return path
# Remaining case is relative paths, which may be relative to a different
# directory (os.getcwd()) than the needed `base`, so we "rebase" it.
return os.path.relpath(path, base)
def search_path(paths, path):
for p in paths:
f = os.path.join(p, path)
if os.path.isfile(f):
return f
raise RuntimeError(f"Cannot find {path}")
# Preprocess all the direct and indirect inputs of midl, and put all the
# preprocessed inputs in the given `base` directory. Returns a tuple containing
# the path of the main preprocessed input, and the modified flags to use instead
# of the flags given as argument.
def preprocess(base, input, flags):
import argparse
import re
from collections import deque
IMPORT_RE = re.compile('import\s*"([^"]+)";')
parser = argparse.ArgumentParser()
parser.add_argument("-I", action="append")
parser.add_argument("-D", action="append")
args, remainder = parser.parse_known_args(flags)
preprocessor = (
# Ideally we'd use the real midl version, but querying it adds a
# significant overhead to configure. In practice, the version number
# doesn't make a difference at the moment.
+ ["-E", "-D__midl=801"]
+ [f"-D{d}" for d in args.D or ()]
+ [f"-I{i}" for i in args.I or ()]
includes = ["."] + buildconfig.substs["INCLUDE"].split(";") + (args.I or [])
seen = set()
queue = deque([input])
if args.acf:
output = os.path.join(base, os.path.basename(input))
while True:
input = queue.popleft()
except IndexError:
if os.path.basename(input) in seen:
input = search_path(includes, input)
# If there is a .acf file corresponding to the .idl we're processing,
# we also want to preprocess that file because midl might look for it too.
if input.endswith(".idl") and os.path.exists(input[:-4] + ".acf"):
queue.append(input[:-4] + ".acf")
command = preprocessor + [input]
preprocessed = os.path.join(base, os.path.basename(input)), stdout=open(preprocessed, "wb"), check=True)
# Read the resulting file, and search for imports, that we'll want to
# preprocess as well.
with open(preprocessed, "r") as fh:
for line in fh:
if not line.startswith("import"):
m = IMPORT_RE.match(line)
if not m:
imp =
flags = []
# Add -I<base> first in the flags, so that midl resolves imports to the
# preprocessed files we created.
for i in [base] + (args.I or []):
flags.extend(["-I", i])
# Add the preprocessed acf file if one was given on the command line.
if args.acf:
flags.extend(["-acf", os.path.join(base, os.path.basename(args.acf))])
return output, flags
def midl(out, input, *flags):
midl_flags = buildconfig.substs["MIDL_FLAGS"]
base = os.path.dirname( or "."
tmpdir = None
# If the build system is asking to not use the preprocessor to midl,
# we need to do the preprocessing ourselves.
if "-no_cpp" in midl_flags:
# Normally, we'd use tempfile.TemporaryDirectory, but in this specific
# case, we actually want a deterministic directory name, because it's
# recorded in the code midl generates.
tmpdir = os.path.join(base, os.path.basename(input) + ".tmp")
os.makedirs(tmpdir, exist_ok=True)
input, flags = preprocess(tmpdir, input, flags)
except subprocess.CalledProcessError as e:
return e.returncode
midl = buildconfig.substs["MIDL"]
wine = buildconfig.substs.get("WINE")
if midl.lower().endswith(".exe") and wine:
command = [wine, midl]
command = [midl]
command.extend([relativize(f, base) for f in flags])
command.append(relativize(input, base))
print("Executing:", " ".join(command))
result =, cwd=base)
return result.returncode
if tmpdir:
# midl outputs dlldata to a single dlldata.c file by default. This prevents running
# midl in parallel in the same directory for idl files that would generate dlldata.c
# because of race conditions updating the file. Instead, we ask midl to create
# separate files, and we merge them manually.
def merge_dlldata(out, *inputs):
inputs = [open(i) for i in inputs]
read_a_line = [True] * len(inputs)
while True:
lines = [
f.readline() if read_a_line[n] else lines[n] for n, f in enumerate(inputs)
unique_lines = set(lines)
if len(unique_lines) == 1:
# All the lines are identical
if not lines[0]:
read_a_line = [True] * len(inputs)
elif (
len(unique_lines) == 2
and len([l for l in unique_lines if "#define" in l]) == 1
# Most lines are identical. When they aren't, it's typically because some
# files have an extra #define that others don't. When that happens, we
# print out the #define, and get a new input line from the files that had
# a #define on the next iteration. We expect that next line to match what
# the other files had on this iteration.
# Note: we explicitly don't support the case where there are different
# defines across different files, except when there's a different one
# for each file, in which case it's handled further below.
a = unique_lines.pop()
if "#define" in a:
read_a_line = ["#define" in l for l in lines]
elif len(unique_lines) != len(lines):
# If for some reason, we don't get lines that are entirely different
# from each other, we have some unexpected input.
"Error while merging dlldata. Last lines read: {}".format(lines),
return 1
for line in lines:
read_a_line = [True] * len(inputs)
return 0