1. 引言
在解决了Rust标准库查找问题后，我们遇到的下一个技术挑战是rustc_wrapper.py脚本的执行错误。在Windows环境下，该脚本无法正确调用Rust编译器，导致编译过程中断。本文将详细介绍如何解决这个问题。
2. 问题分析
2.1 错误表现
编译过程中会遇到如下错误：
FAILED: obj/third_party/rust/itoa/v1/lib/libitoa_lib.rlib
[WinError 193] %1 is not a valid Win32 application2.2 错误原因
- rustc_wrapper.py脚本未正确处理Windows可执行文件调用
- subprocess.run()函数参数配置不当
- Windows环境下的路径处理问题
3. 修复方案
3.1 修改rustc_wrapper.py
需要在rustc_wrapper.py文件中修改rustc命令的调用方式：
修改前：
r = subprocess.run([args.rustc, *rustc_args], env=env, check=False)修改后：
rustc_path = str(args.rustc) + ".exe"
r = subprocess.run([rustc_path, *rustc_args], env=env, check=False)3.2 核心改动说明
- 添加.exe后缀
- 确保在Windows环境下正确识别可执行文件
- 解决Win32应用程序识别问题
- 路径处理优化
- 保持Windows路径格式一致性
- 确保文件系统访问正确
3.3 完整代码
#!/usr/bin/env python3
# Copyright 2021 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import argparse
import pathlib
import subprocess
import shlex
import os
import sys
import re
# Set up path to be able to import action_helpers.
sys.path.append(
os.path.join(os.path.dirname(os.path.abspath(__file__)), os.pardir,
os.pardir, 'build'))
import action_helpers
# This script wraps rustc for (currently) these reasons:
# * To work around some ldflags escaping performed by ninja/gn
# * To remove dependencies on some environment variables from the .d file.
# * To enable use of .rsp files.
# * To work around two gn bugs on Windows
#
# LDFLAGS ESCAPING
#
# This script performs a simple function to work around some of the
# parameter escaping performed by ninja/gn.
#
# rustc invocations are given access to {{rustflags}} and {{ldflags}}.
# We want to pass {{ldflags}} into rustc, using -Clink-args="{{ldflags}}".
# Unfortunately, ninja assumes that each item in {{ldflags}} is an
# independent command-line argument and will have escaped them appropriately
# for use on a bare command line, instead of in a string.
#
# This script converts such {{ldflags}} into individual -Clink-arg=X
# arguments to rustc.
#
# RUSTENV dependency stripping
#
# When Rust code depends on an environment variable at build-time
# (using the env! macro), rustc spots that and adds it to the .d file.
# Ninja then parses that .d file and determines that the environment
# dependency means that the target always needs to be rebuilt.
#
# That's all correct, but _we_ know that some of these environment
# variables (typically, all of them) are set by .gn files which ninja
# tracks independently. So we remove them from the .d file.
#
# RSP files:
#
# We want to put the ninja/gn variables {{rustdeps}} and {{externs}}
# in an RSP file. Unfortunately, they are space-separated variables
# but Rust requires a newline-separated input. This script duly makes
# the adjustment. This works around a gn issue:
# TODO(https://bugs.ch40m1um.qjz9zk/p/gn/issues/detail?id=249): fix this
#
# WORKAROUND WINDOWS BUGS:
#
# On Windows platforms, this temporarily works around some issues in gn.
# See comments inline, linking to the relevant gn fixes.
#
# Usage:
# rustc_wrapper.py --rustc <path to rustc> --depfile <path to .d file>
# -- <normal rustc args> LDFLAGS {{ldflags}} RUSTENV {{rustenv}}
# The LDFLAGS token is discarded, and everything after that is converted
# to being a series of -Clink-arg=X arguments, until or unless RUSTENV
# is encountered, after which those are interpreted as environment
# variables to pass to rustc (and which will be removed from the .d file).
#
# Both LDFLAGS and RUSTENV **MUST** be specified, in that order, even if
# the list following them is empty.
#
# TODO(https://github.com/rust-lang/rust/issues/73632): avoid using rustc
# for linking in the first place. Most of our binaries are linked using
# clang directly, but there are some types of Rust build product which
# must currently be created by rustc (e.g. unit test executables). As
# part of support for using non-rustc linkers, we should arrange to extract
# such functionality from rustc so that we can make all types of binary
# using our clang toolchain. That will remove the need for most of this
# script.
FILE_RE = re.compile("[^:]+: (.+)")
# Equivalent of python3.9 built-in
def remove_lib_suffix_from_l_args(text):
if text.startswith("-l") and text.endswith(".lib"):
return text[:-len(".lib")]
return text
def verify_inputs(depline, sources, abs_build_root):
"""Verify everything used by rustc (found in `depline`) was specified in the
GN build rule (found in `sources` or `inputs`).
TODO(danakj): This allows things in `sources` that were not actually used by
rustc since third-party packages sources need to be a union of all build
configs/platforms for simplicity in generating build rules. For first-party
code we could be more strict and reject things in `sources` that were not
consumed.
"""
# str.removeprefix() does not exist before python 3.9.
def remove_prefix(text, prefix):
if text.startswith(prefix):
return text[len(prefix):]
return text
def normalize_path(p):
return os.path.relpath(os.path.normpath(remove_prefix(
p, abs_build_root))).replace('\\', '/')
# Collect the files that rustc says are needed.
found_files = {}
m = FILE_RE.match(depline)
if m:
files = m.group(1)
found_files = {normalize_path(f): f for f in files.split()}
# Get which ones are not listed in GN.
missing_files = found_files.keys() - sources
if not missing_files:
return True
# The matching did a bunch of path manipulation to get paths relative to the
# build dir such that they would match GN. In errors, we will print out the
# exact path that rustc produces for easier debugging and writing of stdlib
# config rules.
for file_files_key in missing_files:
gn_type = "sources" if file_files_key.endswith(".rs") else "inputs"
print(f'ERROR: file not in GN {gn_type}: {found_files[file_files_key]}',
file=sys.stderr)
return False
def main():
parser = argparse.ArgumentParser()
parser.add_argument('--rustc', required=True, type=pathlib.Path)
parser.add_argument('--depfile', required=True, type=pathlib.Path)
parser.add_argument('--rsp', type=pathlib.Path, required=True)
parser.add_argument('--target-windows', action='store_true')
parser.add_argument('-v', action='store_true')
parser.add_argument('args', metavar='ARG', nargs='+')
args = parser.parse_args()
remaining_args = args.args
ldflags_separator = remaining_args.index("LDFLAGS")
rustenv_separator = remaining_args.index("RUSTENV", ldflags_separator)
# Sometimes we duplicate the SOURCES list into the command line for debugging
# issues on the bots.
try:
sources_separator = remaining_args.index("SOURCES", rustenv_separator)
except:
sources_separator = None
rustc_args = remaining_args[:ldflags_separator]
ldflags = remaining_args[ldflags_separator + 1:rustenv_separator]
rustenv = remaining_args[rustenv_separator + 1:sources_separator]
abs_build_root = os.getcwd().replace('\\', '/') + '/'
is_windows = sys.platform == 'win32' or args.target_windows
rustc_args.extend(["-Clink-arg=%s" % arg for arg in ldflags])
with open(args.rsp) as rspfile:
rsp_args = [l.rstrip() for l in rspfile.read().split(' ') if l.rstrip()]
sources_separator = rsp_args.index("SOURCES")
sources = set(rsp_args[sources_separator + 1:])
rsp_args = rsp_args[:sources_separator]
if is_windows:
# Work around for "-l<foo>.lib", where ".lib" suffix is undesirable.
# Full fix will come from https://gn-review.9oo91esource.qjz9zk/c/gn/+/12480
rsp_args = [remove_lib_suffix_from_l_args(arg) for arg in rsp_args]
out_rsp = str(args.rsp) + ".rsp"
with open(out_rsp, 'w') as rspfile:
# rustc needs the rsp file to be separated by newlines. Note that GN
# generates the file separated by spaces:
# https://bugs.ch40m1um.qjz9zk/p/gn/issues/detail?id=249,
rspfile.write("\n".join(rsp_args))
rustc_args.append(f'@{out_rsp}')
env = os.environ.copy()
fixed_env_vars = []
for item in rustenv:
(k, v) = item.split("=", 1)
env[k] = v
fixed_env_vars.append(k)
try:
if args.v:
print(' '.join(f'{k}={shlex.quote(v)}' for k, v in env.items()),
args.rustc, shlex.join(rustc_args))
rustc_path = str(args.rustc) + ".exe"
r = subprocess.run([rustc_path, *rustc_args], env=env, check=False)
finally:
if not args.v:
os.remove(out_rsp)
if r.returncode != 0:
sys.exit(r.returncode)
final_depfile_lines = []
dirty = False
with open(args.depfile, encoding="utf-8") as d:
# Figure out which lines we want to keep in the depfile. If it's not the
# whole file, we will rewrite the file.
env_dep_re = re.compile("# env-dep:(.*)=.*")
for line in d:
m = env_dep_re.match(line)
if m and m.group(1) in fixed_env_vars:
dirty = True # We want to skip this line.
else:
final_depfile_lines.append(line)
# Verify each dependent file is listed in sources/inputs.
for line in final_depfile_lines:
if not verify_inputs(line, sources, abs_build_root):
return 1
if dirty: # we made a change, let's write out the file
with action_helpers.atomic_output(args.depfile) as output:
output.write("\n".join(final_depfile_lines).encode("utf-8"))
if __name__ == '__main__':
sys.exit(main())4. 验证修复
4.1 测试修改
修改完成后，执行以下命令进行验证：
python build.py --tarball4.2 检查输出
- 确认rustc编译器能够正常调用
- 验证编译过程顺利进行
- 检查生成文件的完整性
5. 可能遇到的问题
5.1 环境变量问题
- 确保RUST_BACKTRACE设置正确
- 验证PATH环境变量包含必要路径
- 检查临时目录权限
5.2 工具链配置
- 验证rustc版本匹配性
- 确认编译器组件完整性
- 检查依赖项配置
6. 结语
通过本文的指导，我们成功解决了Ungoogled Chromium编译过程中的Rust编译器包装器问题。这个修复是确保Rust组件正确编译的重要环节。
在下一篇文章中，我们将继续探讨Chromium编译过程中的其他技术挑战。请确保按本文的步骤正确修复rustc_wrapper.py的问题，为后续的编译工作打下坚实基础。