Merge branch 'ps/ci-rust'

CI improvements to handle the recent Rust integration better.

* ps/ci-rust:
rust: support for Windows
ci: verify minimum supported Rust version
ci: check for common Rust mistakes via Clippy
rust/varint: add safety comments
ci: check formatting of our Rust code
ci: deduplicate calls to `apt-get update`

.github/workflows/main.yml

···
     - run: ci/install-dependencies.sh
     - run: ci/run-static-analysis.sh
     - run: ci/check-directional-formatting.bash
+  rust-analysis:
+    needs: ci-config
+    if: needs.ci-config.outputs.enabled == 'yes'
+    env:
+      jobname: RustAnalysis
+      CI_JOB_IMAGE: ubuntu:rolling
+    runs-on: ubuntu-latest
+    container: ubuntu:rolling
+    concurrency:
+      group: rust-analysis-${{ github.ref }}
+      cancel-in-progress: ${{ needs.ci-config.outputs.skip_concurrent == 'yes' }}
+    steps:
+    - uses: actions/checkout@v4
+    - run: ci/install-dependencies.sh
+    - run: ci/run-rust-checks.sh
   sparse:
     needs: ci-config
     if: needs.ci-config.outputs.enabled == 'yes'

.gitlab-ci.yml

···
     - saas-windows-medium-amd64
   before_script:
     - *windows_before_script
-    - choco install -y git meson ninja
+    - choco install -y git meson ninja rust-ms
     - Import-Module $env:ChocolateyInstall\helpers\chocolateyProfile.psm1
     - refreshenv
 
···
   script:
     - ./ci/run-static-analysis.sh
     - ./ci/check-directional-formatting.bash
+
+rust-analysis:
+  image: ubuntu:rolling
+  stage: analyze
+  needs: [ ]
+  variables:
+    jobname: RustAnalysis
+  before_script:
+    - ./ci/install-dependencies.sh
+  script:
+    - ./ci/run-rust-checks.sh
 
 check-whitespace:
   image: ubuntu:latest

Cargo.toml

···
 name = "gitcore"
 version = "0.1.0"
 edition = "2018"
+rust-version = "1.49.0"
 
 [lib]
 crate-type = ["staticlib"]

Makefile

···
 TEST_SHELL_PATH = $(SHELL_PATH)
 
 LIB_FILE = libgit.a
+
 ifdef DEBUG
-RUST_LIB = target/debug/libgitcore.a
+RUST_TARGET_DIR = target/debug
+else
+RUST_TARGET_DIR = target/release
+endif
+
+ifeq ($(uname_S),Windows)
+RUST_LIB = $(RUST_TARGET_DIR)/gitcore.lib
 else
-RUST_LIB = target/release/libgitcore.a
+RUST_LIB = $(RUST_TARGET_DIR)/libgitcore.a
 endif
 
 GITLIBS = common-main.o $(LIB_FILE)
···
 ifdef WITH_RUST
 BASIC_CFLAGS += -DWITH_RUST
 GITLIBS += $(RUST_LIB)
+ifeq ($(uname_S),Windows)
+EXTLIBS += -luserenv
+endif
 endif
 
 ifdef SANITIZE

ci/install-dependencies.sh

···
 P4WHENCE=https://cdist2.perforce.com/perforce/r23.2
 LFSWHENCE=https://github.com/github/git-lfs/releases/download/v$LINUX_GIT_LFS_VERSION
 JGITWHENCE=https://repo1.maven.org/maven2/org/eclipse/jgit/org.eclipse.jgit.pgm/6.8.0.202311291450-r/org.eclipse.jgit.pgm-6.8.0.202311291450-r.sh
+CARGO_MSRV_VERSION=0.18.4
+CARGO_MSRV_WHENCE=https://github.com/foresterre/cargo-msrv/releases/download/v$CARGO_MSRV_VERSION/cargo-msrv-x86_64-unknown-linux-musl-v$CARGO_MSRV_VERSION.tgz
 
 # Make sudo a no-op and execute the command directly when running as root.
 # While using sudo would be fine on most platforms when we are root already,
···
 
 case "$jobname" in
 ClangFormat)
-	sudo apt-get -q update
 	sudo apt-get -q -y install clang-format
 	;;
 StaticAnalysis)
-	sudo apt-get -q update
 	sudo apt-get -q -y install coccinelle libcurl4-openssl-dev libssl-dev \
 		libexpat-dev gettext make
 	;;
+RustAnalysis)
+	sudo apt-get -q -y install rustup
+	rustup default stable
+	rustup component add clippy rustfmt
+
+	wget -q "$CARGO_MSRV_WHENCE" -O "cargo-msvc.tgz"
+	sudo mkdir -p "$CUSTOM_PATH"
+	sudo tar -xf "cargo-msvc.tgz" --strip-components=1 \
+		--directory "$CUSTOM_PATH" --wildcards "*/cargo-msrv"
+	sudo chmod a+x "$CUSTOM_PATH/cargo-msrv"
+	;;
 sparse)
-	sudo apt-get -q update -q
 	sudo apt-get -q -y install libssl-dev libcurl4-openssl-dev \
 		libexpat-dev gettext zlib1g-dev sparse
 	;;
 Documentation)
-	sudo apt-get -q update
 	sudo apt-get -q -y install asciidoc xmlto docbook-xsl-ns make
 
 	test -n "$ALREADY_HAVE_ASCIIDOCTOR" ||

ci/run-rust-checks.sh

···
+#!/bin/sh
+
+. ${0%/*}/lib.sh
+
+set +x
+
+if ! group "Check Rust formatting" cargo fmt --all --check
+then
+	RET=1
+fi
+
+if ! group "Check for common Rust mistakes" cargo clippy --all-targets --all-features -- -Dwarnings
+then
+	RET=1
+fi
+
+if ! group "Check for minimum required Rust version" cargo msrv verify
+then
+	RET=1
+fi
+
+exit $RET

meson.build

···
 if rust_option.allowed()
   subdir('src')
   libgit_c_args += '-DWITH_RUST'
+
+  if host_machine.system() == 'windows'
+    libgit_dependencies += compiler.find_library('userenv')
+  endif
 else
   libgit_sources += [
     'varint.c',

src/cargo-meson.sh

···
 	exit $RET
 fi
 
-if ! cmp "$BUILD_DIR/$BUILD_TYPE/libgitcore.a" "$BUILD_DIR/libgitcore.a" >/dev/null 2>&1
+case "$(cargo -vV | sed -s 's/^host: \(.*\)$/\1/')" in
+	*-windows-*)
+		LIBNAME=gitcore.lib;;
+	*)
+		LIBNAME=libgitcore.a;;
+esac
+
+if ! cmp "$BUILD_DIR/$BUILD_TYPE/$LIBNAME" "$BUILD_DIR/libgitcore.a" >/dev/null 2>&1
 then
-	cp "$BUILD_DIR/$BUILD_TYPE/libgitcore.a" "$BUILD_DIR/libgitcore.a"
+	cp "$BUILD_DIR/$BUILD_TYPE/$LIBNAME" "$BUILD_DIR/libgitcore.a"
 fi

src/varint.rs

···
+/// Decode the variable-length integer stored in `bufp` and return the decoded value.
+///
+/// Returns 0 in case the decoded integer would overflow u64::MAX.
+///
+/// # Safety
+///
+/// The buffer must be NUL-terminated to ensure safety.
 #[no_mangle]
 pub unsafe extern "C" fn decode_varint(bufp: *mut *const u8) -> u64 {
     let mut buf = *bufp;
···
     val
 }
 
+/// Encode `value` into `buf` as a variable-length integer unless `buf` is null.
+///
+/// Returns the number of bytes written, or, if `buf` is null, the number of bytes that would be
+/// written to encode the integer.
+///
+/// # Safety
+///
+/// `buf` must either be null or point to at least 16 bytes of memory.
 #[no_mangle]
 pub unsafe extern "C" fn encode_varint(value: u64, buf: *mut u8) -> u8 {
     let mut varint: [u8; 16] = [0; 16];