Add Alpine Linux build support and musl libc detection

This commit adds support for building ring-ftp on Alpine Linux by:
- Creating a new GitHub Actions workflow for Alpine builds using Docker
- Adding musl libc auto-detection in CMakeLists.txt
- Updating the main workflow to include Alpine builds in the pipeline

Author: ysdragon

.github/workflows/alpine_build.yml

@@ -0,0 +1,54 @@
+name: Alpine Build
+
+on:
+  workflow_call:
+    inputs:
+      ring-version:
+        required: true
+        type: string
+
+jobs:
+  build:
+    runs-on: ${{ matrix.arch == 'amd64' && 'ubuntu-latest' || 'ubuntu-24.04-arm' }}
+    strategy:
+      matrix:
+        include:
+        - arch: amd64
+          name: alpine-amd64
+        - arch: arm64
+          name: alpine-arm64
+
+    steps:
+    - name: Checkout ring-ftp
+      uses: actions/checkout@v4
+      with:
+        submodules: recursive
+
+    - name: Build in Alpine container
+      run: |
+        docker run --rm \
+          -v ${{ github.workspace }}:/workspace \
+          -w /workspace \
+          alpine:latest /bin/sh -c "
+            apk add --no-cache cmake ninja gcc g++ musl-dev linux-headers git curl-dev
+
+            # Clone Ring Language
+            git clone --branch ${{ inputs.ring-version }} --depth 1 https://github.com/ring-lang/ring.git ring
+
+            # Build Ring Language
+            cd ring/language
+            cmake . -DCMAKE_BUILD_TYPE=Release -GNinja
+            ninja install
+            cd /workspace
+
+            # Build ring-ftp lib
+            rm -rf lib
+            cmake . -DCMAKE_BUILD_TYPE=Release -DRING_ROOT=/workspace/ring -DMUSL=ON -GNinja
+            ninja
+          "
+
+    - name: Upload artifacts
+      uses: actions/upload-artifact@v4
+      with:
+        name: ring-ftp-${{ matrix.name }}
+        path: lib

.github/workflows/main.yml

@@ -20,6 +20,11 @@ on:
     - 'src/c_src/ftpclient'
 
 jobs:
+  alpine:
+    uses: ./.github/workflows/alpine_build.yml
+    with:
+      ring-version: v1.24
+
   freebsd:
     uses: ./.github/workflows/freebsd_build.yml
     with:
@@ -42,7 +47,7 @@ jobs:
 
   update-libs:
     runs-on: ubuntu-latest
-    needs: [ freebsd, macos, ubuntu, windows ]
+    needs: [ alpine, freebsd, macos, ubuntu, windows ]
     if: github.event_name == 'push' && github.ref == 'refs/heads/master'
 
     permissions:

CMakeLists.txt

@@ -66,8 +66,30 @@ if(NOT DEFINED ARCH_DIR)
     endif()
 endif()
 
+# Detect musl libc
+option(MUSL "Build for musl libc" OFF)
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+	# Auto-detect musl if not explicitly set
+	if(NOT MUSL)
+		execute_process(
+			COMMAND ldd --version
+			OUTPUT_VARIABLE LDD_OUTPUT
+			ERROR_VARIABLE LDD_OUTPUT
+			OUTPUT_STRIP_TRAILING_WHITESPACE
+		)
+		if(LDD_OUTPUT MATCHES "musl")
+			set(MUSL ON)
+			message(STATUS "Detected musl libc")
+		endif()
+	endif()
+endif()
+
 # Set the destination directory for the built library
-set(LIB_DEST_DIR "${CMAKE_CURRENT_SOURCE_DIR}/lib/${OS_DIR}/${ARCH_DIR}")
+if(MUSL AND OS_DIR STREQUAL "linux")
+	set(LIB_DEST_DIR "${CMAKE_CURRENT_SOURCE_DIR}/lib/${OS_DIR}/musl/${ARCH_DIR}")
+else()
+	set(LIB_DEST_DIR "${CMAKE_CURRENT_SOURCE_DIR}/lib/${OS_DIR}/${ARCH_DIR}")
+endif()
 
 # Find libcurl
 find_package(CURL REQUIRED)