cargo-linker - mozsearch

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#!/usr/bin/env python3

# If you want to use a custom linker with Cargo, Cargo requires that you

# specify it in Cargo.toml or via the matching environment variable.

# Passing extra options to the linker is possible with Cargo via

# RUSTFLAGS='-C link-args', but testing showed that doing this reliably

# was difficult.

# Our solution to these problems is to use this wrapper script.  We pass

# in the LD and the LDFLAGS to use via environment variables.

# * MOZ_CARGO_WRAP_LD is equivalent to CC on Unix-y platforms, and CC

#   frequently has additional arguments in addition to the compiler

#   itself.

# * MOZ_CARGO_WRAP_LDFLAGS contains space-separated arguments to pass,

#   and not quoting it ensures that each of those arguments is passed

#   as a separate argument to the actual LD.

# * In rare cases, we also need MOZ_CARGO_WRAP_LD_CXX, which is the

#   equivalent of CXX, when linking C++ code. Usually, this should

#   simply work by the use of CC and -lstdc++ (added by cc-rs).

#   However, in the case of sanitizer runtimes, there is a separate

#   runtime for C and C++ and linking C++ code with the C runtime can

#   fail if the requested feature is in the C++ runtime only (bug 1747298).

import os

import sys

# This is not necessarily run with a virtualenv python, so add

# the necessary directory for the shellutil module.

base_dir = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))

sys.path.insert(0, os.path.join(base_dir, "python", "mozbuild"))

from mozbuild.shellutil import split

SANITIZERS = {

    "asan": "address",

    "hwasan": "hwaddress",

    "lsan": "leak",

    "msan": "memory",

    "tsan": "thread",

use_clang_sanitizer = os.environ.get("MOZ_CLANG_NEWER_THAN_RUSTC_LLVM")

wrap_ld = os.environ["MOZ_CARGO_WRAP_LD"]

args = []

for arg in sys.argv[1:]:

    if arg in ["-lc++", "-lstdc++"]:

        wrap_ld = os.environ["MOZ_CARGO_WRAP_LD_CXX"]

    elif use_clang_sanitizer and arg.endswith("san.a"):

        # When clang is newer than rustc's LLVM, we replace rust's sanitizer

        # runtimes with clang's.

        filename = os.path.basename(arg)

        prefix, dot, suffix = filename[:-2].rpartition(".")

        if (

            prefix.startswith("librustc-")

            and prefix.endswith("_rt") and dot == "."

):

            args.append(f"-fsanitize={SANITIZERS[suffix]}")

            continue

    args.append(arg)

args.extend(split(os.environ["MOZ_CARGO_WRAP_LDFLAGS"]))

wrap_ld = split(wrap_ld)

os.execvp(wrap_ld[0], wrap_ld + args)