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.
+
+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
