added CLOSE_RANGE_UNSHARE defined for syscall of close_range.

.github/workflows/ci.yml

@@ -141,6 +141,43 @@ jobs:
           cd ../boost-root
           ./b2 -j3 libs/$LIBRARY/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} variant=debug,release
 
+  alpine-linux:
+    runs-on: ubuntu-latest
+    container:
+      image: alpine:3.20.1
+    steps:
+      - name: Install packages
+        run: apk add g++ git python3 linux-headers
+
+      - uses: actions/checkout@v4
+
+      - name: Setup Boost
+        run: |
+          echo GITHUB_REPOSITORY: $GITHUB_REPOSITORY
+          LIBRARY=${GITHUB_REPOSITORY#*/}
+          echo LIBRARY: $LIBRARY
+          echo "LIBRARY=$LIBRARY" >> $GITHUB_ENV
+          echo GITHUB_BASE_REF: $GITHUB_BASE_REF
+          echo GITHUB_REF: $GITHUB_REF
+          REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+          REF=${REF#refs/heads/}
+          echo REF: $REF
+          BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
+          echo BOOST_BRANCH: $BOOST_BRANCH
+          cd ..
+          git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          cp -r $GITHUB_WORKSPACE/* libs/$LIBRARY
+          git submodule update --init tools/boostdep
+          python3 tools/boostdep/depinst/depinst.py --git_args "--jobs 3" $LIBRARY
+          ./bootstrap.sh
+          ./b2 -d0 headers
+
+      - name: Run tests
+        run: |
+          cd ../boost-root
+          ./b2 -j3 libs/$LIBRARY/test toolset=gcc cxxstd=23 variant=debug,release
+
   windows:
     strategy:
       fail-fast: false

src/posix/close_handles.cpp

@@ -60,6 +60,10 @@ int fdwalk(int (*func)(void *, int), void *cd);
 #if defined(SYS_close_range)
 
 #define BOOST_PROCESS_V2_HAS_CLOSE_RANGE 1
+#if !defined(CLOSE_RANGE_UNSHARE)
+#define CLOSE_RANGE_UNSHARE 2
+#endif
+
 int close_range(unsigned int first, unsigned int last, int flags)
 {
   return ::syscall(SYS_close_range, first, last, flags);