backend/tests: add interop_echo_server (doesn't check that it works yet)

backend.native/tests/build.gradle

@@ -1122,6 +1122,11 @@ kotlinNativeInterop {
         target 'native'
         compilerOpts '-D_POSIX_SOURCE' // Exclude Darwin extensions causing link errors.
     }
+
+    sockets {
+        defFile 'interop/basics/sockets.def'
+        target 'native'
+    }
 }
 
 task interop0(type: RunInteropKonanTest) {
@@ -1141,3 +1146,11 @@ task interop2(type: RunInteropKonanTest) {
     source = "interop/basics/2.kt"
     interop = 'cstdio'
 }
+
+task interop_echo_server(type: RunInteropKonanTest) {
+    if (isLinux()) {
+        disabled = true
+    }
+    source = "interop/basics/echo_server.kt"
+    interop = 'sockets'
+}

backend.native/tests/interop/basics/echo_server.kt

@@ -0,0 +1,73 @@
+import kotlinx.cinterop.*
+import sockets.*
+
+val AF_INET: Byte = 2
+val SOCK_STREAM = 1
+
+fun main(args: Array<String>) {
+    if (args.size == 0) {
+        return
+    }
+
+    val port = atoi(args[0]).toShort()
+
+    memScoped {
+
+        val bufferLength = 100L
+        val buffer = allocArray<CInt8Var>(bufferLength)
+        val serverAddr = alloc<sockaddr_in>()
+
+        val listenFd = socket(AF_INET.toInt(), SOCK_STREAM, 0)
+                .ensureUnixCallResult { it >= 0 }
+
+        with(serverAddr) {
+            memset(this.ptr, 0, sockaddr_in.size)
+            sin_family.value = AF_INET
+            sin_addr.s_addr.value = htons(0).toInt()
+            sin_port.value = htons(port)
+        }
+
+        bind(listenFd, serverAddr.ptr.reinterpret(), sockaddr_in.size.toInt())
+                .ensureUnixCallResult { it == 0 }
+
+        listen(listenFd, 10)
+                .ensureUnixCallResult { it == 0 }
+
+        val commFd = accept(listenFd, null, null)
+                .ensureUnixCallResult { it >= 0 }
+
+        while (true) {
+            val length = read(commFd, buffer.ptr, bufferLength)
+                    .ensureUnixCallResult { it >= 0 }
+
+            if (length == 0L) {
+                break
+            }
+
+            write(commFd, buffer.ptr, length)
+                    .ensureUnixCallResult { it >= 0 }
+        }
+    }
+}
+
+// Not available through interop because declared as macro:
+fun htons(value: Short) = ((value.toInt() ushr 8) or (value.toInt() shl 8)).toShort()
+
+fun throwUnixError(): Nothing {
+    perror(null) // TODO: store error message to exception instead.
+    throw Error("UNIX call failed")
+}
+
+inline fun Int.ensureUnixCallResult(predicate: (Int) -> Boolean): Int {
+    if (!predicate(this)) {
+        throwUnixError()
+    }
+    return this
+}
+
+inline fun Long.ensureUnixCallResult(predicate: (Long) -> Boolean): Long {
+    if (!predicate(this)) {
+        throwUnixError()
+    }
+    return this
+}

backend.native/tests/interop/basics/sockets.def

@@ -0,0 +1,5 @@
+headers = sys/socket.h netdb.h stdio.h string.h unistd.h stdlib.h arpa/inet.h
+excludedFunctions = _IO_flockfile _IO_funlockfile _IO_ftrylockfile _IO_cleanup_region_start _IO_cleanup_region_end \
+    mkstemp_dprotected_np
+
+compilerOpts = -D_POSIX_SOURCE