On Tue, Jul 22, 2025 at 11:36 AM Paolo Bonzini <pbonz...@redhat.com> wrote:
>
> Some distros prefer to avoid vendored crate sources, and instead use
> local sources from e.g. ``/usr/share/cargo/registry``. Add a
> script, inspired by the Mesa spec file(*), that automatically
> performs this task. The script is meant to be invoked after unpacking
> the QEMU tarball.
>
> (*) This is the hack that Mesa uses:
>
> export MESON_PACKAGE_CACHE_DIR="%{cargo_registry}/"
> %define inst_crate_nameversion() %(basename %{cargo_registry}/%{1}-*)
> %define rewrite_wrap_file() sed -e "/source.*/d" -e
> "s/%{1}-.*/%{inst_crate_nameversion %{1}}/" -i subprojects/%{1}.wrap
> %rewrite_wrap_file proc-macro2
> ... more %rewrite_wrap_file invocations follow ...
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> docs/about/build-platforms.rst | 8 +
> scripts/get-wraps-from-cargo-registry.py | 191 +++++++++++++++++++++++
> 2 files changed, 199 insertions(+)
> create mode 100755 scripts/get-wraps-from-cargo-registry.py
>
> diff --git a/docs/about/build-platforms.rst b/docs/about/build-platforms.rst
> index 8ecbd6b26f7..8671c3be9cd 100644
> --- a/docs/about/build-platforms.rst
> +++ b/docs/about/build-platforms.rst
> @@ -127,6 +127,14 @@ Rust build dependencies
> (or newer) package. The path to ``rustc`` and ``rustdoc`` must be
> provided manually to the configure script.
>
> + Some distros prefer to avoid vendored crate sources, and instead use
> + local sources from e.g. ``/usr/share/cargo/registry``. QEMU includes a
> + script, ``scripts/get-wraps-from-cargo-registry.py``, that automatically
> + performs this task. The script is meant to be invoked after unpacking
> + the QEMU tarball. QEMU also includes ``rust/Cargo.toml`` and
> + ``rust/Cargo.lock`` files that can be used to compute QEMU's build
> + dependencies, e.g. using ``cargo2rpm -p rust/Cargo.toml buildrequires``.
> +
> Optional build dependencies
> Build components whose absence does not affect the ability to build QEMU
> may not be available in distros, or may be too old for our requirements.
> diff --git a/scripts/get-wraps-from-cargo-registry.py
> b/scripts/get-wraps-from-cargo-registry.py
> new file mode 100755
> index 00000000000..6b76d00a6d9
> --- /dev/null
> +++ b/scripts/get-wraps-from-cargo-registry.py
> @@ -0,0 +1,191 @@
> +#!/usr/bin/env python3
> +
> +"""
> +get-wraps-from-cargo-registry.py - Update Meson subprojects from a global
> registry
> +"""
> +
> +# Copyright (C) 2025 Red Hat, Inc.
> +#
> +# Author: Paolo Bonzini <pbonz...@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.
> +
Nit, missing:
# SPDX-License-Identifier:
> +import argparse
> +import configparser
> +import filecmp
> +import glob
> +import os
> +import subprocess
> +import sys
> +
> +
> +def get_name_and_semver(namever: str) -> tuple[str, str]:
> + """Split a subproject name into its name and semantic version parts"""
> + parts = namever.rsplit("-", 1)
> + if len(parts) != 2:
> + return namever, ""
> +
> + return parts[0], parts[1]
> +
> +
> +class UpdateSubprojects:
> + cargo_registry: str
> + top_srcdir: str
> + dry_run: bool
> + changes: int = 0
> +
> + def find_installed_crate(self, namever: str) -> str | None:
> + """Find installed crate matching name and semver prefix"""
> + name, semver = get_name_and_semver(namever)
> +
> + # exact version match
> + path = os.path.join(self.cargo_registry, f"{name}-{semver}")
> + if os.path.exists(path):
> + return f"{name}-{semver}"
> +
> + # semver match
> + matches = sorted(glob.glob(f"{path}.*"))
> + return os.path.basename(matches[0]) if matches else None
> +
> + def compare_build_rs(self, orig_dir: str, registry_namever: str) -> None:
> + """Warn if the build.rs in the original directory differs from the
> registry version."""
> + orig_build_rs = os.path.join(orig_dir, "build.rs")
> + new_build_rs = os.path.join(self.cargo_registry, registry_namever,
> "build.rs")
> +
> + msg = None
> + if os.path.isfile(orig_build_rs) != os.path.isfile(new_build_rs):
> + if os.path.isfile(orig_build_rs):
> + msg = f"build.rs removed in {registry_namever}"
> + if os.path.isfile(new_build_rs):
> + msg = f"build.rs added in {registry_namever}"
> +
> + elif os.path.isfile(orig_build_rs) and not
> filecmp.cmp(orig_build_rs, new_build_rs):
> + msg = f"build.rs changed from {orig_dir} to {registry_namever}"
> +
> + if msg:
> + print(f"⚠️ Warning: {msg}")
> + print(" This may affect the build process - please review the
> differences.")
> +
> + def update_subproject(self, wrap_file: str, registry_namever: str) ->
> None:
> + """Modify [wrap-file] section to point to self.cargo_registry."""
> + assert wrap_file.endswith("-rs.wrap")
> + wrap_name = wrap_file[:-5]
> +
> + env = os.environ.copy()
> + env["MESON_PACKAGE_CACHE_DIR"] = self.cargo_registry
> +
> + config = configparser.ConfigParser()
> + config.read(wrap_file)
> + if "wrap-file" not in config:
> + return
> +
> + # do not download the wrap, always use the local copy
> + orig_dir = config["wrap-file"]["directory"]
> + if os.path.exists(orig_dir) and orig_dir != registry_namever:
> + self.compare_build_rs(orig_dir, registry_namever)
> + if self.dry_run:
> + if orig_dir == registry_namever:
> + print(f"Will install {orig_dir} from registry.")
> + else:
> + print(f"Will replace {orig_dir} with {registry_namever}.")
> + self.changes += 1
> + return
> +
> + config["wrap-file"]["directory"] = registry_namever
> + for key in list(config["wrap-file"].keys()):
> + if key.startswith("source"):
> + del config["wrap-file"][key]
> +
> + # replace existing directory with installed version
> + if os.path.exists(orig_dir):
> + subprocess.run(
> + ["meson", "subprojects", "purge", "--confirm", wrap_name],
> + cwd=self.top_srcdir,
> + env=env,
> + check=True,
> + )
> +
> + with open(wrap_file, "w") as f:
> + config.write(f)
> +
> + if orig_dir == registry_namever:
> + print(f"Installing {orig_dir} from registry.")
> + else:
> + print(f"Replacing {orig_dir} with {registry_namever}.")
> +
> + if orig_dir != registry_namever:
> + patch_dir = config["wrap-file"]["patch_directory"]
> + patch_dir = os.path.join("packagefiles", patch_dir)
> + _, ver = registry_namever.rsplit("-", 1)
> + subprocess.run(
> + ["meson", "rewrite", "kwargs", "set", "project", "/",
> "version", ver],
> + cwd=patch_dir,
> + env=env,
> + check=True,
> + )
> +
> + subprocess.run(
> + ["meson", "subprojects", "download", wrap_name],
> + cwd=self.top_srcdir,
> + env=env,
> + check=True,
> + )
> +
> + @staticmethod
> + def parse_cmdline() -> argparse.Namespace:
> + parser = argparse.ArgumentParser(
> + description="Replace Meson subprojects with packages in a Cargo
> registry"
> + )
> + parser.add_argument(
> + "--cargo-registry",
> + default=os.environ.get("CARGO_REGISTRY"),
> + help="Path to Cargo registry (default: CARGO_REGISTRY env var)",
> + )
> + parser.add_argument(
> + "--dry-run",
> + action="store_true",
> + default=False,
> + help="Do not actually replace anything",
> + )
> +
> + args = parser.parse_args()
> + if not args.cargo_registry:
> + print("error: CARGO_REGISTRY environment variable not set and
> --cargo-registry not provided")
> + sys.exit(1)
> +
> + return args
> +
> + def __init__(self, args: argparse.Namespace):
> + self.cargo_registry = args.cargo_registry
> + self.dry_run = args.dry_run
> + self.top_srcdir = os.getcwd()
> +
> + def main(self) -> None:
> + if not os.path.exists("subprojects"):
> + print("'subprojects' directory not found, nothing to do.")
> + return
> +
> + os.chdir("subprojects")
> + for wrap_file in sorted(glob.glob("*-rs.wrap")):
> + namever = wrap_file[:-8] # Remove '-rs.wrap'
> +
> + registry_namever = self.find_installed_crate(namever)
> + if not registry_namever:
> + print(f"No installed crate found for {wrap_file}")
> + continue
> +
> + self.update_subproject(wrap_file, registry_namever)
> +
> + if self.changes:
> + if self.dry_run:
> + print("Rerun without --dry-run to apply changes.")
> + else:
> + print(f"✨ {self.changes} subproject(s) updated!")
> + else:
> + print("No changes.")
> +
> +
> +if __name__ == "__main__":
> + args = UpdateSubprojects.parse_cmdline()
> + UpdateSubprojects(args).main()
> --
> 2.50.1
>
>
