AudioServer: Assorted infrastructure work

* Add a LibAudio, and move WAV file parsing there (via AWavFile and AWavLoader)
* Add CLocalSocket, and CSocket::connect() variant for local address types.
  We make some small use of this in WindowServer (as that's where we
  modelled it from), but don't get too invasive as this PR is already
  quite large, and the WS I/O is a bit carefully done
* Add an AClientConnection which will eventually be used to talk to
  AudioServer (and make use of it in Piano, though right now it really
  doesn't do anything except connect, using our new CLocalSocket...)

Libraries/LibCore/CEventLoop.h

@@ -6,11 +6,11 @@
 #include <AK/Vector.h>
 #include <AK/WeakPtr.h>
 #include <LibCore/CLock.h>
+#include <LibCore/CEvent.h>
 #include <sys/select.h>
 #include <sys/time.h>
 #include <time.h>
 
-class CEvent;
 class CObject;
 class CNotifier;
 

Libraries/LibCore/CLocalSocket.cpp

@@ -0,0 +1,19 @@
+#include <LibCore/CLocalSocket.h>
+#include <sys/socket.h>
+
+CLocalSocket::CLocalSocket(CObject* parent)
+    : CSocket(CSocket::Type::Local, parent)
+{
+    int fd = socket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
+    if (fd < 0) {
+        set_error(fd);
+    } else {
+        set_fd(fd);
+        set_mode(CIODevice::ReadWrite);
+        set_error(0);
+    }
+}
+
+CLocalSocket::~CLocalSocket()
+{
+}

Libraries/LibCore/CLocalSocket.h

@@ -0,0 +1,7 @@
+#include <LibCore/CSocket.h>
+
+class CLocalSocket final : public CSocket {
+public:
+    explicit CLocalSocket(CObject* parent = nullptr);
+    virtual ~CLocalSocket() override;
+};

Libraries/LibCore/CSocket.cpp

@@ -35,6 +35,8 @@ bool CSocket::connect(const CSocketAddress& address, int port)
 {
     ASSERT(!is_connected());
     ASSERT(address.type() == CSocketAddress::Type::IPv4);
+    dbgprintf("Connecting to %s...", address.to_string().characters());
+
     ASSERT(port > 0 && port <= 65535);
 
     struct sockaddr_in addr;
@@ -47,7 +49,6 @@ bool CSocket::connect(const CSocketAddress& address, int port)
     m_destination_address = address;
     m_destination_port = port;
 
-    dbgprintf("Connecting to %s...", address.to_string().characters());
     fflush(stdout);
     int rc = ::connect(fd(), (struct sockaddr*)&addr, sizeof(addr));
     if (rc < 0) {
@@ -71,6 +72,26 @@ bool CSocket::connect(const CSocketAddress& address, int port)
     return true;
 }
 
+bool CSocket::connect(const CSocketAddress& address)
+{
+    ASSERT(!is_connected());
+    ASSERT(address.type() == CSocketAddress::Type::Local);
+    dbgprintf("Connecting to %s...", address.to_string().characters());
+
+    sockaddr_un saddr;
+    saddr.sun_family = AF_LOCAL;
+    strcpy(saddr.sun_path, address.to_string().characters());
+
+    int rc = ::connect(fd(), (const sockaddr*)&saddr, sizeof(saddr));
+    if (rc < 0) {
+        perror("connect");
+        return false;
+    }
+
+    m_connected = true;
+    return true;
+}
+
 ByteBuffer CSocket::receive(int max_size)
 {
     auto buffer = read(max_size);

Libraries/LibCore/CSocket.h

@@ -10,12 +10,14 @@ public:
     enum class Type {
         Invalid,
         TCP,
-        UDP
+        UDP,
+        Local,
     };
     virtual ~CSocket() override;
 
     bool connect(const String& hostname, int port);
     bool connect(const CSocketAddress&, int port);
+    bool connect(const CSocketAddress&);
 
     ByteBuffer receive(int max_size);
     bool send(const ByteBuffer&);

Libraries/LibCore/CSocketAddress.h

@@ -17,6 +17,14 @@ public:
     {
     }
 
+    static CSocketAddress local(const String& address)
+    {
+        CSocketAddress addr;
+        addr.m_type = Type::Local;
+        addr.m_local_address = address;
+        return addr;
+    }
+
     Type type() const { return m_type; }
     bool is_valid() const { return m_type != Type::Invalid; }
     IPv4Address ipv4_address() const { return m_ipv4_address; }
@@ -26,6 +34,8 @@ public:
         switch (m_type) {
         case Type::IPv4:
             return m_ipv4_address.to_string();
+        case Type::Local:
+            return m_local_address;
         default:
             return "[CSocketAddress]";
         }
@@ -34,4 +44,5 @@ public:
 private:
     Type m_type { Type::Invalid };
     IPv4Address m_ipv4_address;
+    String m_local_address;
 };

Libraries/LibCore/Makefile

@@ -5,6 +5,7 @@ OBJS = \
     CIODevice.o \
     CFile.o \
     CSocket.o \
+    CLocalSocket.o \
     CTCPSocket.o \
     CElapsedTimer.o \
     CNotifier.o \