Swift linux sdk support

.github/workflow/test-swift-build-with-musl-and-glibc.yaml

@@ -0,0 +1,48 @@
+name: Test swift build with musl and glibc
+
+on:
+    pull_request:
+        branches: [master]
+
+jobs:
+    build-image-glibc:
+        name: Normal swift build i.e. glibc
+        container:
+            image: swift:6.1
+        runs-on: ubuntu-latest
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@v4
+
+            - name: Cache build dependencies
+              uses: actions/cache@v4
+              with:
+                path: .build
+                key: ${{ runner.os }}-build-${{ hashFiles('Package.resolved') }}
+
+            - name: Build
+              run: swift build
+
+    build-image-musl:
+        name: Build image using swift container plugin i.e. musl
+        runs-on: ubuntu-latest
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@v4
+
+            - name: Cache build dependencies
+              uses: actions/cache@v4
+              with:
+                path: .build
+                key: ${{ runner.os }}-build-${{ hashFiles('Package.resolved') }}
+
+            - name: Install the static SDK
+              run: |
+                  swift sdk install \
+                      https://download.swift.org/swift-6.1-release/static-sdk/swift-6.1-RELEASE/swift-6.1-RELEASE_static-linux-0.0.1.artifactbundle.tar.gz \
+                      --checksum 111c6f7d280a651208b8c74c0521dd99365d785c1976a6e23162f55f65379ac6
+
+            - name: Build 
+              run: |
+                  swift build \
+                      --swift-sdk x86_64-swift-linux-musl

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.1
+// swift-tools-version:5.9
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 /**

Sources/Signals/Signals.swift

@@ -21,7 +21,11 @@
 #if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
 	import Darwin
 #elseif os(Linux)
-	import Glibc
+    #if canImport(Musl)
+    import Musl
+    #else
+    import Glibc
+    #endif
 #endif
 
 import Foundation
@@ -90,8 +94,16 @@ public class Signals {
                 return Int32(SIGPROF)
             case .winch:
                 return Int32(SIGWINCH)
-            case .info:
-                return Int32(SIGINFO)
+
+#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS) || canImport(Glibc)
+            case .info: return Int32(SIGINFO)
+#elseif os(Linux)
+    #if canImport(Musl)
+            case .info: return Int32(SIGUSR1) // No SIGINFO signal in Musl. SIGUSR1 may be the best alternative for SIGINFO in Musl
+    #else
+            case .info: return Int32(SIGINFO)
+    #endif
+#endif
 			case .user(let sig):
 				return Int32(sig)
 
@@ -117,8 +129,16 @@ public class Signals {
             case Int(SIGIO): self = .io
             case Int(SIGPROF): self = .prof
             case Int(SIGWINCH): self = .winch
+#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS) || canImport(Glibc)
             case Int(SIGINFO): self = .info
-
+#elseif os(Linux)
+    #if canImport(Musl)
+            // no SIGINFO in Musl
+    #else
+            case Int(SIGINFO): self = .info
+    #endif
+#endif
+
             default:
                 self = .user(rawValue)
             }
@@ -154,14 +174,17 @@ public class Signals {
 				sigaction(signal.rawValue, actionPointer, nil)
 			}
 
-		#elseif os(Linux)
-
-			var sigAction = sigaction()
-
-			sigAction.__sigaction_handler = unsafeBitCast(action, to: sigaction.__Unnamed_union___sigaction_handler.self)
-
-			_ = sigaction(signal.rawValue, &sigAction, nil)
-
+        #elseif os(Linux)
+            #if canImport(Musl)
+                // Musl: sigAction is not supported or need more research for alternative
+            #else
+                var sigAction = sigaction()
+
+                sigAction.__sigaction_handler = unsafeBitCast(action, to: sigaction.__Unnamed_union___sigaction_handler.self)
+
+                _ = sigaction(signal.rawValue, &sigAction, nil)
+            #endif
+
 		#endif
 	}
 
@@ -201,13 +224,13 @@ public class Signals {
 	public class func raise(signal: Signal) {
 
 		#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
-
 			_ = Darwin.raise(signal.rawValue)
-
-		#elseif os(Linux)
-
-			_ = Glibc.raise(signal.rawValue)
-
+        #elseif os(Linux)
+            #if canImport(Musl)
+                _ = Musl.raise(signal.rawValue)
+            #else
+                _ = Glibc.raise(signal.rawValue)
+            #endif
 		#endif
 	}
 
@@ -221,12 +244,13 @@ public class Signals {
 		#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
 
 			_ = Darwin.signal(signal.rawValue, SIG_IGN)
-
-		#elseif os(Linux)
-
-			_ = Glibc.signal(signal.rawValue, SIG_IGN)
-
-		#endif
+        #elseif os(Linux)
+            #if canImport(Musl)
+                _ = Musl.signal(signal.rawValue, SIG_IGN)
+            #else
+                _ = Glibc.signal(signal.rawValue, SIG_IGN)
+            #endif
+        #endif
 	}
 
 	///
@@ -237,14 +261,14 @@ public class Signals {
 	public class func restore(signal: Signal) {
 
 		#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
-
 			_ = Darwin.signal(signal.rawValue, SIG_DFL)
-
-		#elseif os(Linux)
-
-			_ = Glibc.signal(signal.rawValue, SIG_DFL)
-
-		#endif
+        #elseif os(Linux)
+            #if canImport(Musl)
+                _ = Musl.signal(signal.rawValue, SIG_DFL)
+            #else
+                _ = Glibc.signal(signal.rawValue, SIG_DFL)
+            #endif
+        #endif
 	}
 
 }