Re: [RFC PATCH v1 1/6] build-sys: Add rust feature option

[Manos Pitsidianakis]

On Tue, 11 Jun 2024 at 17:05, Stefan Hajnoczi <stefanha@redhat.com> wrote:
>
> On Mon, Jun 10, 2024 at 09:22:36PM +0300, Manos Pitsidianakis wrote:
> > Add options for Rust in meson_options.txt, meson.build, configure to
> > prepare for adding Rust code in the followup commits.
> >
> > `rust` is a reserved meson name, so we have to use an alternative.
> > `with_rust` was chosen.
> >
> > Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
> > ---
> > The cargo wrapper script hardcodes some rust target triples. This is
> > just temporary.
> > ---
> >  .gitignore               |   2 +
> >  configure                |  12 +++
> >  meson.build              |  11 ++
> >  meson_options.txt        |   4 +
> >  scripts/cargo_wrapper.py | 211 +++++++++++++++++++++++++++++++++++++++
> >  5 files changed, 240 insertions(+)
> >  create mode 100644 scripts/cargo_wrapper.py
> >
> > diff --git a/.gitignore b/.gitignore
> > index 61fa39967b..f42b0d937e 100644
> > --- a/.gitignore
> > +++ b/.gitignore
> > @@ -2,6 +2,8 @@
> >  /build/
> >  /.cache/
> >  /.vscode/
> > +/target/
> > +rust/**/target
>
> Are these necessary since the cargo build command-line below uses
> --target-dir <meson-build-dir>?
>
> Adding new build output directories outside build/ makes it harder to
> clean up the source tree and ensure no state from previous builds
> remains.

Agreed! These build directories would show up when using cargo
directly instead of through the cargo_wrapper.py script, i.e. during
development. I'd consider it an edge case, it won't happen much and if
it does it's better to gitignore them than accidentally checking them
in. Also, whatever artifacts are in a `target` directory won't be used
for compilation with qemu inside a build directory.


> >  *.pyc
> >  .sdk
> >  .stgit-*
> > diff --git a/configure b/configure
> > index 38ee257701..c195630771 100755
> > --- a/configure
> > +++ b/configure
> > @@ -302,6 +302,9 @@ else
> >    objcc="${objcc-${cross_prefix}clang}"
> >  fi
> >
> > +with_rust="auto"
> > +with_rust_target_triple=""
> > +
> >  ar="${AR-${cross_prefix}ar}"
> >  as="${AS-${cross_prefix}as}"
> >  ccas="${CCAS-$cc}"
> > @@ -760,6 +763,12 @@ for opt do
> >    ;;
> >    --gdb=*) gdb_bin="$optarg"
> >    ;;
> > +  --enable-rust) with_rust=enabled
> > +  ;;
> > +  --disable-rust) with_rust=disabled
> > +  ;;
> > +  --rust-target-triple=*) with_rust_target_triple="$optarg"
> > +  ;;
> >    # everything else has the same name in configure and meson
> >    --*) meson_option_parse "$opt" "$optarg"
> >    ;;
> > @@ -1796,6 +1805,9 @@ if test "$skip_meson" = no; then
> >    test -n "${LIB_FUZZING_ENGINE+xxx}" && meson_option_add 
> > "-Dfuzzing_engine=$LIB_FUZZING_ENGINE"
> >    test "$plugins" = yes && meson_option_add "-Dplugins=true"
> >    test "$tcg" != enabled && meson_option_add "-Dtcg=$tcg"
> > +  test "$with_rust" != enabled && meson_option_add "-Dwith_rust=$with_rust"
> > +  test "$with_rust" != enabled && meson_option_add "-Dwith_rust=$with_rust"
>
> Duplicate line.

Thanks!

>
> > +  test "$with_rust_target_triple" != "" && meson_option_add 
> > "-Dwith_rust_target_triple=$with_rust_target_triple"
> >    run_meson() {
> >      NINJA=$ninja $meson setup "$@" "$PWD" "$source_path"
> >    }
> > diff --git a/meson.build b/meson.build
> > index a9de71d450..3533889852 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -290,6 +290,12 @@ foreach lang : all_languages
> >    endif
> >  endforeach
> >
> > +cargo = not_found
> > +if get_option('with_rust').allowed()
> > +  cargo = find_program('cargo', required: get_option('with_rust'))
> > +endif
> > +with_rust = cargo.found()
> > +
> >  # default flags for all hosts
> >  # We use -fwrapv to tell the compiler that we require a C dialect where
> >  # left shift of signed integers is well defined and has the expected
> > @@ -2066,6 +2072,7 @@ endif
> >
> >  config_host_data = configuration_data()
> >
> > +config_host_data.set('CONFIG_WITH_RUST', with_rust)
> >  audio_drivers_selected = []
> >  if have_system
> >    audio_drivers_available = {
> > @@ -4190,6 +4197,10 @@ if 'objc' in all_languages
> >  else
> >    summary_info += {'Objective-C compiler': false}
> >  endif
> > +summary_info += {'Rust support':      with_rust}
> > +if with_rust and get_option('with_rust_target_triple') != ''
> > +  summary_info += {'Rust target':     
> > get_option('with_rust_target_triple')}
> > +endif
> >  option_cflags = (get_option('debug') ? ['-g'] : [])
> >  if get_option('optimization') != 'plain'
> >    option_cflags += ['-O' + get_option('optimization')]
> > diff --git a/meson_options.txt b/meson_options.txt
> > index 4c1583eb40..223491b731 100644
> > --- a/meson_options.txt
> > +++ b/meson_options.txt
> > @@ -366,3 +366,7 @@ option('qemu_ga_version', type: 'string', value: '',
> >
> >  option('hexagon_idef_parser', type : 'boolean', value : true,
> >         description: 'use idef-parser to automatically generate TCG code 
> > for the Hexagon frontend')
> > +option('with_rust', type: 'feature', value: 'auto',
> > +       description: 'Enable Rust support')
> > +option('with_rust_target_triple', type : 'string', value: '',
> > +       description: 'Rust target triple')
> > diff --git a/scripts/cargo_wrapper.py b/scripts/cargo_wrapper.py
> > new file mode 100644
> > index 0000000000..d338effdaa
> > --- /dev/null
> > +++ b/scripts/cargo_wrapper.py
> > @@ -0,0 +1,211 @@
> > +#!/usr/bin/env python3
> > +# Copyright (c) 2020 Red Hat, Inc.
> > +# Copyright (c) 2023 Linaro Ltd.
> > +#
> > +# Authors:
> > +#  Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
> > +#  Marc-André Lureau <marcandre.lureau@redhat.com>
> > +#
> > +# This work is licensed under the terms of the GNU GPL, version 2 or
> > +# later.  See the COPYING file in the top-level directory.
> > +
> > +import argparse
> > +import configparser
> > +import distutils.file_util
> > +import json
> > +import logging
> > +import os
> > +import os.path
> > +import re
> > +import subprocess
> > +import sys
> > +import pathlib
> > +import shutil
> > +import tomllib
> > +
> > +from pathlib import Path
> > +from typing import Any, Dict, List, Tuple
> > +
> > +RUST_TARGET_TRIPLES = (
> > +    "aarch64-unknown-linux-gnu",
> > +    "x86_64-unknown-linux-gnu",
> > +    "x86_64-apple-darwin",
> > +    "aarch64-apple-darwin",
> > +)
>
> Is this hardcoded to avoid calling `rustc --print target-list`?
>
> Or is this the support matrix? In that case it would be interesting to
> figure out the target triples for all host OSes and CPUs that QEMU is
> supported on.

Yes, it's what I tested it on (the x86-64-apple-darwin part through rosetta).

Do you think running -print target-list would be a better choice here?
This is only for providing the valid choices for the target triplet
CLI argument in argparse.


>
> > +
> > +
> > +def cfg_name(name: str) -> str:
> > +    if (
> > +        name.startswith("CONFIG_")
> > +        or name.startswith("TARGET_")
> > +        or name.startswith("HAVE_")
> > +    ):
> > +        return name
> > +    return ""
> > +
> > +
> > +def generate_cfg_flags(header: str) -> List[str]:
> > +    with open(header, encoding="utf-8") as cfg:
> > +        config = [l.split()[1:] for l in cfg if l.startswith("#define")]
> > +
> > +    cfg_list = []
> > +    for cfg in config:
> > +        name = cfg_name(cfg[0])
> > +        if not name:
> > +            continue
> > +        if len(cfg) >= 2 and cfg[1] != "1":
> > +            continue
> > +        cfg_list.append("--cfg")
> > +        cfg_list.append(name)
> > +    return cfg_list
> > +
> > +
> > +def cargo_target_dir(args: argparse.Namespace) -> pathlib.Path:
> > +    return args.meson_build_dir
> > +
> > +
> > +def manifest_path(args: argparse.Namespace) -> pathlib.Path:
> > +    return args.crate_dir / "Cargo.toml"
> > +
> > +
> > +def get_cargo_rustc(args: argparse.Namespace) -> tuple[Dict[str, Any], 
> > List[str]]:
> > +    # See 
> > https://doc.rust-lang.org/cargo/reference/environment-variables.html
> > +    # Item `CARGO_ENCODED_RUSTFLAGS — A list of custom flags separated by
> > +    # 0x1f (ASCII Unit Separator) to pass to all compiler invocations that 
> > Cargo
> > +    # performs`
> > +    cfg = chr(0x1F).join(
> > +        [c for h in args.config_headers for c in generate_cfg_flags(h)]
> > +    )
> > +    target_dir = cargo_target_dir(args)
> > +    cargo_path = manifest_path(args)
> > +
> > +    cargo_cmd = [
> > +        "cargo",
> > +        "build",
> > +        "--target-dir",
> > +        str(target_dir),
> > +        "--manifest-path",
> > +        str(cargo_path),
> > +    ]
> > +    if args.target_triple:
> > +        cargo_cmd += ["--target", args.target_triple]
> > +    if args.profile == "release":
> > +        cargo_cmd += ["--release"]
> > +
> > +    env = os.environ
> > +    env["CARGO_ENCODED_RUSTFLAGS"] = cfg
> > +
> > +    return (env, cargo_cmd)
> > +
> > +
> > +def run_cargo(env: Dict[str, Any], cargo_cmd: List[str]) -> str:
> > +    envlog = " ".join(["{}={}".format(k, v) for k, v in env.items()])
> > +    cmdlog = " ".join(cargo_cmd)
> > +    logging.debug("Running %s %s", envlog, cmdlog)
> > +    try:
> > +        out = subprocess.check_output(
> > +            cargo_cmd,
> > +            env=dict(os.environ, **env),
> > +            stderr=subprocess.STDOUT,
> > +            universal_newlines=True,
> > +        )
> > +    except subprocess.CalledProcessError as err:
> > +        print("Environment: " + envlog)
> > +        print("Command: " + cmdlog)
> > +        print(err.output)
> > +        sys.exit(1)
> > +
> > +    return out
> > +
> > +
> > +def build_lib(args: argparse.Namespace) -> None:
> > +    logging.debug("build-lib")
> > +    target_dir = cargo_target_dir(args)
> > +    cargo_toml_path = manifest_path(args)
> > +
> > +    with open(cargo_toml_path, "rb") as f:
> > +        config = tomllib.load(f)
> > +
> > +    package_name = config["package"]["name"].strip('"').replace("-", "_")
> > +
> > +    liba_filename = "lib" + package_name + ".a"
> > +    liba = target_dir / args.target_triple / args.profile / liba_filename
> > +
> > +    env, cargo_cmd = get_cargo_rustc(args)
> > +    out = run_cargo(env, cargo_cmd)
> > +    logging.debug("cp %s %s", liba, args.outdir)
> > +    shutil.copy2(liba, args.outdir)
> > +
> > +
> > +def main() -> None:
> > +    parser = argparse.ArgumentParser()
> > +    parser.add_argument("-v", "--verbose", action="store_true")
> > +    parser.add_argument(
> > +        "--color",
> > +        metavar="WHEN",
> > +        choices=["auto", "always", "never"],
> > +        default="auto",
> > +        help="Coloring: auto, always, never",
> > +    )
> > +    parser.add_argument(
> > +        "--config-headers",
> > +        metavar="CONFIG_HEADER",
> > +        action="append",
> > +        dest="config_headers",
> > +        required=False,
> > +        default=[],
> > +    )
> > +    parser.add_argument(
> > +        "--meson-build-dir",
> > +        metavar="BUILD_DIR",
> > +        help="meson.current_build_dir()",
> > +        type=pathlib.Path,
> > +        dest="meson_build_dir",
> > +        required=True,
> > +    )
> > +    parser.add_argument(
> > +        "--meson-source-dir",
> > +        metavar="SOURCE_DIR",
> > +        help="meson.current_source_dir()",
> > +        type=pathlib.Path,
> > +        dest="meson_source_dir",
> > +        required=True,
> > +    )
> > +    parser.add_argument(
> > +        "--crate-dir",
> > +        metavar="CRATE_DIR",
> > +        type=pathlib.Path,
> > +        dest="crate_dir",
> > +        help="Absolute path that contains the manifest file of the crate 
> > to compile",
> > +        required=True,
> > +    )
> > +    parser.add_argument(
> > +        "--outdir",
> > +        metavar="OUTDIR",
> > +        type=pathlib.Path,
> > +        dest="outdir",
> > +        help="Path to copy compiled artifacts to for Meson to use.",
> > +        required=True,
> > +    )
> > +    parser.add_argument(
> > +        "--profile", type=str, choices=["release", "debug"], required=True
> > +    )
> > +    parser.add_argument(
> > +        "--target-triple", type=str, choices=RUST_TARGET_TRIPLES, 
> > required=True
> > +    )
> > +
> > +    subparsers = parser.add_subparsers()
> > +
> > +    buildlib = subparsers.add_parser("build-lib")
> > +    buildlib.set_defaults(func=build_lib)
> > +
> > +    args = parser.parse_args()
> > +    if args.verbose:
> > +        logging.basicConfig(level=logging.DEBUG)
> > +    logging.debug("args: %s", args)
> > +
> > +    args.func(args)
> > +
> > +
> > +if __name__ == "__main__":
> > +    main()
> > --
> > γαῖα πυρί μιχθήτω
> >