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...)

Applications/Piano/Makefile

@@ -11,7 +11,7 @@ DEFINES += -DUSERLAND
 all: $(APP)
 
 $(APP): $(OBJS)
-	$(LD) -o $(APP) $(LDFLAGS) $(OBJS) -lgui -lcore -lc
+	$(LD) -o $(APP) $(LDFLAGS) $(OBJS) -lgui -lcore -lc -laudio
 
 .cpp.o:
 	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<

Applications/Piano/main.cpp

@@ -2,6 +2,7 @@
 #include "PianoWidget.h"
 #include <LibCore/CFile.h>
 #include <LibCore/CNotifier.h>
+#include <LibAudio/AClientConnection.h>
 #include <LibGUI/GApplication.h>
 #include <LibGUI/GEventLoop.h>
 #include <LibGUI/GWindow.h>
@@ -10,6 +11,7 @@ static int s_pipefds[2];
 
 int main(int argc, char** argv)
 {
+    AClientConnection audio_connection;
     GApplication app(argc, argv);
 
     pipe(s_pipefds);

Kernel/makeall.sh

@@ -24,6 +24,7 @@ build_targets="$build_targets ../Servers/WindowServer"
 build_targets="$build_targets ../Servers/AudioServer"
 build_targets="$build_targets ../Libraries/LibGUI"
 build_targets="$build_targets ../Libraries/LibHTML"
+build_targets="$build_targets ../Libraries/LibAudio"
 build_targets="$build_targets ../Userland"
 build_targets="$build_targets ../Applications/Terminal"
 build_targets="$build_targets ../Applications/FontEditor"

Libraries/LibAudio/AClientConnection.cpp

@@ -0,0 +1,26 @@
+#include "AClientConnection.h"
+#include <unistd.h>
+#include <stdio.h>
+
+AClientConnection::AClientConnection()
+{
+    m_connection.on_connected = [this] {
+        m_notifier = make<CNotifier>(m_connection.fd(), CNotifier::Read);
+        m_notifier->on_ready_to_read = [this] { printf("AudioServer said something to us"); };
+        m_connection.write("Hello, friends");
+    };
+
+    int retries = 1000;
+    while (retries) {
+        if (m_connection.connect(CSocketAddress::local("/tmp/asportal"))) {
+            break;
+        }
+
+#ifdef ACLIENT_DEBUG
+        dbgprintf("AClientConnection: connect failed: %d, %s\n", errno, strerror(errno));
+#endif
+        sleep(1);
+        --retries;
+    }
+}
+

Libraries/LibAudio/AClientConnection.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <LibCore/CLocalSocket.h>
+#include <LibCore/CNotifier.h>
+
+class AClientConnection {
+public:
+    AClientConnection();
+
+private:
+    CLocalSocket m_connection;
+    OwnPtr<CNotifier> m_notifier;
+};

Libraries/LibAudio/AWavFile.cpp

@@ -0,0 +1,2 @@
+#include "AWavFile.h"
+

Libraries/LibAudio/AWavFile.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <AK/RefCounted.h>
+#include <AK/ByteBuffer.h>
+#include <AK/Types.h>
+
+class AWavFile : public RefCounted<AWavFile> {
+public:
+    enum class Format {
+        Invalid,
+        PCM,
+    };
+
+    Format format() const { return m_format; }
+    u16 channel_count() const { return m_channel_count; }
+    u32 sample_rate_per_second() const { return m_sample_rate; }
+    u32 average_byte_rate_per_second() const { return m_byte_rate; }
+    u16 block_align() const { return m_block_align; }
+    u16 bits_per_sample() const { return m_bits_per_sample; }
+    const ByteBuffer& sample_data() const { return m_sample_data; }
+
+private:
+    Format m_format = Format::Invalid;
+    u16 m_channel_count = 0;
+    u32 m_sample_rate = 0;
+    u32 m_byte_rate = 0;
+    u16 m_block_align = 0;
+    u16 m_bits_per_sample = 0;
+    ByteBuffer m_sample_data;
+
+    friend class AWavLoader;
+};

Libraries/LibAudio/AWavLoader.cpp

@@ -0,0 +1,166 @@
+#include <LibCore/CFile.h>
+
+#include "AWavLoader.h"
+#include "AWavFile.h"
+
+static u32 read_u32(const ByteBuffer& buf, u32& off)
+{
+    ASSERT(buf.size() - off >= 4);
+    u32 b0 = buf[off + 0];
+    u32 b1 = buf[off + 1];
+    u32 b2 = buf[off + 2];
+    u32 b3 = buf[off + 3];
+
+    u32 ret = 0;
+    ret |= (u8(b3) << 24);
+    ret |= (u8(b2) << 16);
+    ret |= (u8(b1) << 8);
+    ret |= (u8(b0));
+
+    off += 4;
+    return ret;
+}
+
+static u16 read_u16(const ByteBuffer& buf, u32& off)
+{
+    ASSERT(buf.size() - off >= 2);
+    u16 b0 = buf[off + 0];
+    u16 b1 = buf[off + 1];
+
+    u16 ret = 0;
+    ret |= (u8(b1) << 8);
+    ret |= (u8(b0));
+
+    off += 2;
+    return ret;
+}
+
+RefPtr<AWavFile> AWavLoader::load_wav(const StringView& path)
+{
+    m_error_string = {};
+
+    CFile wav(path);
+    if (!wav.open(CIODevice::ReadOnly)) {
+        m_error_string = String::format("Can't open file: %s", wav.error_string());
+        return nullptr;
+    }
+
+    const auto& contents = wav.read_all();
+    return parse_wav(contents);
+}
+
+// TODO: A streaming parser might be better than forcing a ByteBuffer
+RefPtr<AWavFile> AWavLoader::parse_wav(const ByteBuffer& buffer)
+{
+    u32 off = 0;
+
+    if (buffer.size() - off < 12) {
+        dbgprintf("WAV is too small (no header, %d bytes)\n", buffer.size());
+        return {};
+    }
+
+    dbgprintf("Trying to parse %d bytes of wav\n", buffer.size());
+
+#define CHECK_OK(msg)                      \
+    do {                                   \
+        ASSERT(ok);                        \
+        if (!ok) {                         \
+            m_error_string = String::format("Parsing failed: %s", msg); \
+            return {};                     \
+        } else {                           \
+            dbgprintf("%s is OK!\n", msg); \
+        }                                  \
+    } while (0);
+
+    bool ok = true;
+    u32 riff = read_u32(buffer, off);
+    ok = ok && riff == 0x46464952; // "RIFF"
+    CHECK_OK("RIFF header");
+
+    u32 sz = read_u32(buffer, off);
+    ASSERT(sz < 1024 * 1024 * 42);
+    ok = ok && sz < 1024 * 1024 * 42; // arbitrary
+    CHECK_OK("File size");
+
+    u32 wave = read_u32(buffer, off);
+    ok = ok && wave == 0x45564157; // "WAVE"
+    CHECK_OK("WAVE header");
+
+    if (buffer.size() - off < 8) {
+        dbgprintf("WAV is too small (no fmt, %d bytes)\n", buffer.size());
+        return {};
+    }
+
+    u32 fmt_id = read_u32(buffer, off);
+    ok = ok && fmt_id == 0x20746D66; // "FMT"
+    CHECK_OK("FMT header");
+
+    u32 fmt_size = read_u32(buffer, off);
+    ok = ok && fmt_size == 16;
+    ASSERT(fmt_size == 16);
+    CHECK_OK("FMT size");
+
+    if (buffer.size() - off < 16) {
+        dbgprintf("WAV is too small (fmt chunk, %d bytes)\n", buffer.size());
+        return {};
+    }
+
+    auto ret = adopt(*new AWavFile);
+    u16 audio_format = read_u16(buffer, off);
+    ok = ok && audio_format == 1; // WAVE_FORMAT_PCM
+    ASSERT(audio_format == 1);
+    CHECK_OK("Audio format");
+    ret->m_format = AWavFile::Format::PCM;
+
+    u16 num_channels = read_u16(buffer, off);
+    CHECK_OK("Channel count");
+    ret->m_channel_count = num_channels;
+
+    u32 sample_rate = read_u32(buffer, off);
+    CHECK_OK("Sample rate");
+    ret->m_sample_rate = sample_rate;
+
+    u32 byte_rate = read_u32(buffer, off);
+    CHECK_OK("Byte rate");
+    ret->m_byte_rate = byte_rate;
+
+    u16 block_align = read_u16(buffer, off);
+    CHECK_OK("Block align");
+    ret->m_block_align = block_align;
+
+    u16 bits_per_sample = read_u16(buffer, off);
+    ok = ok && (bits_per_sample == 8 || bits_per_sample == 16);
+    ASSERT(bits_per_sample == 8 || bits_per_sample == 16);
+    CHECK_OK("Bits per sample");
+    ret->m_bits_per_sample = bits_per_sample;
+
+    // Read chunks until we find DATA
+    if (off >= u32(buffer.size()) - 8) {
+        ok = ok && false;
+        ASSERT_NOT_REACHED();
+        CHECK_OK("Premature EOF without DATA");
+    }
+
+    bool found_data = false;
+    u32 data_sz = 0;
+    while (off < u32(buffer.size()) - 8) {
+        u32 chunk_id = read_u32(buffer, off);
+        data_sz = read_u32(buffer, off);
+        if (chunk_id == 0x61746164) { // DATA
+            found_data = true;
+            break;
+        }
+        off += data_sz;
+    }
+
+    ok = ok && found_data;
+    ASSERT(found_data);
+    CHECK_OK("Found no data chunk");
+
+    ok = ok && data_sz <= (buffer.size() - off);
+    CHECK_OK("Bad DATA size");
+
+    ret->m_sample_data = buffer.slice(off, data_sz);
+    return ret;
+}
+

Libraries/LibAudio/AWavLoader.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include <AK/RefPtr.h>
+
+class AWavFile;
+
+class AWavLoader {
+public:
+    RefPtr<AWavFile> load_wav(const StringView& path);
+    const char* error_string() { return m_error_string.characters(); }
+private:
+    RefPtr<AWavFile> parse_wav(const ByteBuffer& buffer);
+    String m_error_string;
+};

Libraries/LibAudio/Makefile

@@ -0,0 +1,32 @@
+include ../../Makefile.common
+
+OBJS = \
+    AClientConnection.o \
+    AWavFile.o \
+    AWavLoader.o
+
+LIBRARY = libaudio.a
+DEFINES += -DUSERLAND
+
+all: $(LIBRARY)
+
+$(LIBRARY): $(OBJS)
+	@echo "LIB $@"; $(AR) rcs $@ $(OBJS) $(LIBS)
+
+.cpp.o:
+	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<
+
+-include $(OBJS:%.o=%.d)
+
+clean:
+	@echo "CLEAN"; rm -f $(LIBRARY) $(OBJS) *.d
+
+install: $(LIBRARY)
+	mkdir -p ../../Root/usr/include/LibAudio
+	mkdir -p ../../Root/usr/include/AK
+	mkdir -p ../../Root/usr/lib
+	# Copy headers
+	rsync -r -a --include '*/' --include '*.h' --exclude '*' . ../../Root/usr/include/LibAudio
+	rsync -r -a --include '*/' --include '*.h' --exclude '*' ../../AK/ ../../Root/usr/include/AK
+	# Install the library
+	cp $(LIBRARY) ../../Root/usr/lib

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 \

Makefile.common

@@ -8,7 +8,7 @@ MAKEFILE_PATH := $(abspath $(lastword $(MAKEFILE_LIST)))
 SERENITY_BASE_DIR := $(patsubst %/,%,$(dir $(MAKEFILE_PATH)))
 
 INCLUDE_FLAGS = -I$(SERENITY_BASE_DIR) -I$(SERENITY_BASE_DIR)/Libraries -I. -I$(SERENITY_BASE_DIR)/Libraries/LibC -I$(SERENITY_BASE_DIR)/Servers -I$(SERENITY_BASE_DIR)/Libraries/LibM
-LDFLAGS = -L$(SERENITY_BASE_DIR)/Libraries/LibC -L$(SERENITY_BASE_DIR)/Libraries/LibCore -L$(SERENITY_BASE_DIR)/Libraries/LibM -L$(SERENITY_BASE_DIR)/Libraries/LibGUI
+LDFLAGS = -L$(SERENITY_BASE_DIR)/Libraries/LibC -L$(SERENITY_BASE_DIR)/Libraries/LibCore -L$(SERENITY_BASE_DIR)/Libraries/LibM -L$(SERENITY_BASE_DIR)/Libraries/LibGUI -L$(SERENITY_BASE_DIR)/Libraries/LibAudio
 CLANG_FLAGS = -Wconsumed -m32 -ffreestanding -march=i686
 #SUGGEST_FLAGS = -Wsuggest-final-types -Wsuggest-final-methods -Wsuggest-override #-Wsuggest-attribute=noreturn 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(ARCH_FLAGS) $(STANDARD_FLAGS) $(SUGGEST_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)

Servers/AudioServer/Makefile

@@ -11,7 +11,7 @@ DEFINES += -DUSERLAND
 all: $(APP)
 
 $(APP): $(OBJS)
-	$(LD) -o $(APP) $(LDFLAGS) $(OBJS) -lc -lcore
+	$(LD) -o $(APP) $(LDFLAGS) $(OBJS) -lc -lcore -laudio
 
 .cpp.o:
 	@echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<

Servers/AudioServer/main.cpp

@@ -1,160 +1,45 @@
 #include <LibCore/CFile.h>
+#include <LibCore/CEventLoop.h>
+#include <LibCore/CLocalSocket.h>
+#include <LibCore/CNotifier.h>
+#include <LibAudio/AWavLoader.h>
+#include <LibAudio/AWavFile.h>
 
-u32 read_u32(const ByteBuffer& buf, u32& off)
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+class ASEventLoop
 {
-    ASSERT(buf.size() - off >= 4);
-    u32 b0 = buf[off + 0];
-    u32 b1 = buf[off + 1];
-    u32 b2 = buf[off + 2];
-    u32 b3 = buf[off + 3];
+public:
+    ASEventLoop();
+    int exec() { return m_event_loop.exec(); }
+private:
+    CEventLoop m_event_loop;
+    CLocalSocket m_server_sock;
+    OwnPtr<CNotifier> m_server_notifier;
 
-    u32 ret = 0;
-    ret |= (u8(b3) << 24);
-    ret |= (u8(b2) << 16);
-    ret |= (u8(b1) << 8);
-    ret |= (u8(b0));
-
-    off += 4;
-    return ret;
-}
-
-u16 read_u16(const ByteBuffer& buf, u32& off)
-{
-    ASSERT(buf.size() - off >= 2);
-    u16 b0 = buf[off + 0];
-    u16 b1 = buf[off + 1];
-
-    u16 ret = 0;
-    ret |= (u8(b1) << 8);
-    ret |= (u8(b0));
-
-    off += 2;
-    return ret;
-}
-
-ByteBuffer read_wav_data(const StringView& path)
-{
-    CFile wav(path);
-    if (!wav.open(CIODevice::ReadOnly)) {
-        dbgprintf("Can't open wav to dump it to audio: %s", wav.error_string());
-        return {};
-    }
-
-    const auto& contents = wav.read_all();
-    u32 off = 0;
-
-    if (contents.size() - off < 12) {
-        dbgprintf("WAV is too small (no header, %d bytes)\n", contents.size());
-        return {};
-    }
-
-    dbgprintf("Trying to parse %d bytes of wav\n", contents.size());
-
-#define CHECK_OK(msg)                      \
-    do {                                   \
-        ASSERT(ok);                        \
-        if (!ok) {                         \
-            dbgprintf("%s failed\n", msg); \
-            return {};                     \
-        } else {                           \
-            dbgprintf("%S is OK!\n", msg); \
-        }                                  \
-    } while (0);
-
-    bool ok = true;
-    u32 riff = read_u32(contents, off);
-    ok = ok && riff == 0x46464952; // "RIFF"
-    CHECK_OK("RIFF header");
-
-    u32 sz = read_u32(contents, off);
-    ASSERT(sz < 1024 * 1024 * 42);
-    ok = ok && sz < 1024 * 1024 * 42; // arbitrary
-    CHECK_OK("File size");
-
-    u32 wave = read_u32(contents, off);
-    ok = ok && wave == 0x45564157; // "WAVE"
-    CHECK_OK("WAVE header");
-
-    if (contents.size() - off < 8) {
-        dbgprintf("WAV is too small (no fmt, %d bytes)\n", contents.size());
-        return {};
-    }
-
-    u32 fmt_id = read_u32(contents, off);
-    ok = ok && fmt_id == 0x20746D66; // "FMT"
-    CHECK_OK("FMT header");
-
-    u32 fmt_size = read_u32(contents, off);
-    ok = ok && fmt_size == 16;
-    ASSERT(fmt_size == 16);
-    CHECK_OK("FMT size");
-
-    if (contents.size() - off < 16) {
-        dbgprintf("WAV is too small (fmt chunk, %d bytes)\n", contents.size());
-        return {};
-    }
-
-    u16 audio_format = read_u16(contents, off);
-    ok = ok && audio_format == 1; // WAVE_FORMAT_PCM
-    ASSERT(audio_format == 1);
-    CHECK_OK("Audio format");
-
-    u16 num_channels = read_u16(contents, off);
-    ok = ok && num_channels == 1;
-    ASSERT(num_channels == 1);
-    CHECK_OK("Channel count");
-
-    u32 sample_rate = read_u32(contents, off);
-    CHECK_OK("Sample rate");
-
-    off += 4; // bytes per sec: we don't care.
-    off += 2; // block align: we don't care.
-
-    u16 bits_per_sample = read_u16(contents, off);
-    ok = ok && (bits_per_sample == 8 || bits_per_sample == 16);
-    ASSERT(bits_per_sample == 8 || bits_per_sample == 16);
-    CHECK_OK("Bits per sample");
-
-    dbgprintf("Read WAV of format %d with num_channels %d sample rate %d, bits per sample %d\n", audio_format, num_channels, sample_rate, bits_per_sample);
-
-    // Read chunks until we find DATA
-    if (off >= u32(contents.size()) - 8) {
-        ok = ok && false;
-        ASSERT_NOT_REACHED();
-        CHECK_OK("Premature EOF without DATA");
-    }
-
-    bool found_data = false;
-    u32 data_sz = 0;
-    while (off < u32(contents.size()) - 8) {
-        u32 chunk_id = read_u32(contents, off);
-        data_sz = read_u32(contents, off);
-        if (chunk_id == 0x61746164) { // DATA
-            found_data = true;
-            break;
-        }
-        off += data_sz;
-    }
-
-    ok = ok && found_data;
-    ASSERT(found_data);
-    CHECK_OK("Found no data chunk");
-
-    ok = ok && data_sz <= (contents.size() - off);
-    CHECK_OK("Bad DATA size");
-
-    return contents.slice(off, data_sz);
-}
+    void drain_server();
+};
 
 void read_and_play_wav()
 {
     CFile audio("/dev/audio");
     if (!audio.open(CIODevice::WriteOnly)) {
-        dbgprintf("Can't open audio device: %s", audio.error_string());
+        dbgprintf("Can't open audio device: %s\n", audio.error_string());
         return;
     }
 
-    const auto& contents = read_wav_data("/home/anon/tmp.wav");
+    AWavLoader loader;
+    const auto& file = loader.load_wav("/home/anon/tmp.wav");
+    if (!file) {
+        dbgprintf("Can't parse WAV: %s\n", loader.error_string());
+        return;
+    }
+
+    dbgprintf("Read WAV of format %d with num_channels %d sample rate %d, bits per sample %d\n", (u8)file->format(), file->channel_count(), file->sample_rate_per_second(), file->bits_per_sample());
+
+    auto contents = file->sample_data();
     const int chunk_size = 4096;
     int i = 0;
     while (i < contents.size()) {
@@ -164,8 +49,41 @@ void read_and_play_wav()
     }
 }
 
-int main(int, char**)
+ASEventLoop::ASEventLoop()
 {
     read_and_play_wav();
-    return 0;
+
+    unlink("/tmp/asportal");
+
+    sockaddr_un address;
+    address.sun_family = AF_LOCAL;
+    strcpy(address.sun_path, "/tmp/asportal");
+    int rc = bind(m_server_sock.fd(), (const sockaddr*)&address, sizeof(address));
+    ASSERT(rc == 0);
+    rc = listen(m_server_sock.fd(), 5);
+    ASSERT(rc == 0);
+
+    m_server_notifier = make<CNotifier>(m_server_sock.fd(), CNotifier::Read);
+    m_server_notifier->on_ready_to_read = [this] { drain_server(); };
+}
+
+void ASEventLoop::drain_server()
+{
+    sockaddr_un address;
+    socklen_t address_size = sizeof(address);
+    int client_fd = accept(m_server_sock.fd(), (sockaddr*)&address, &address_size);
+    if (client_fd < 0) {
+        dbgprintf("WindowServer: accept() failed: %s\n", strerror(errno));
+    } else {
+        dbgprintf("AudioServer: accept()ed client %d\n", client_fd);
+        String s("hello, client!\n");
+        write(client_fd, s.characters(), s.length());
+        close(client_fd);
+    }
+}
+
+int main(int, char**)
+{
+    ASEventLoop event_loop;
+    return event_loop.exec();
 }

Servers/WindowServer/WSEventLoop.cpp

@@ -26,18 +26,20 @@ WSEventLoop::WSEventLoop()
 
     unlink("/tmp/wsportal");
 
-    m_server_fd = socket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
-    ASSERT(m_server_fd >= 0);
     sockaddr_un address;
     address.sun_family = AF_LOCAL;
     strcpy(address.sun_path, "/tmp/wsportal");
-    int rc = bind(m_server_fd, (const sockaddr*)&address, sizeof(address));
+    int rc = bind(m_server_sock.fd(), (const sockaddr*)&address, sizeof(address));
     ASSERT(rc == 0);
-    rc = listen(m_server_fd, 5);
+    rc = listen(m_server_sock.fd(), 5);
     ASSERT(rc == 0);
 
+    ASSERT(m_server_sock.fd() >= 0);
     ASSERT(m_keyboard_fd >= 0);
     ASSERT(m_mouse_fd >= 0);
+
+    m_server_notifier = make<CNotifier>(m_server_sock.fd(), CNotifier::Read);
+    m_server_notifier->on_ready_to_read = [this] { drain_server(); };
 }
 
 WSEventLoop::~WSEventLoop()
@@ -48,7 +50,7 @@ void WSEventLoop::drain_server()
 {
     sockaddr_un address;
     socklen_t address_size = sizeof(address);
-    int client_fd = accept(m_server_fd, (sockaddr*)&address, &address_size);
+    int client_fd = accept(m_server_sock.fd(), (sockaddr*)&address, &address_size);
     if (client_fd < 0) {
         dbgprintf("WindowServer: accept() failed: %s\n", strerror(errno));
     } else {
@@ -333,7 +335,6 @@ void WSEventLoop::add_file_descriptors_for_select(fd_set& fds, int& max_fd_added
     };
     add_fd_to_set(m_keyboard_fd, fds);
     add_fd_to_set(m_mouse_fd, fds);
-    add_fd_to_set(m_server_fd, fds);
     WSClientConnection::for_each_client([&](WSClientConnection& client) {
         add_fd_to_set(client.fd(), fds);
     });
@@ -341,8 +342,6 @@ void WSEventLoop::add_file_descriptors_for_select(fd_set& fds, int& max_fd_added
 
 void WSEventLoop::process_file_descriptors_after_select(const fd_set& fds)
 {
-    if (FD_ISSET(m_server_fd, &fds))
-        drain_server();
     if (FD_ISSET(m_keyboard_fd, &fds))
         drain_keyboard();
     if (FD_ISSET(m_mouse_fd, &fds))

Servers/WindowServer/WSEventLoop.h

@@ -2,6 +2,8 @@
 
 #include <AK/ByteBuffer.h>
 #include <LibCore/CEventLoop.h>
+#include <LibCore/CNotifier.h>
+#include <LibCore/CLocalSocket.h>
 
 class WSClientConnection;
 struct WSAPI_ClientMessage;
@@ -25,5 +27,6 @@ private:
 
     int m_keyboard_fd { -1 };
     int m_mouse_fd { -1 };
-    int m_server_fd { -1 };
+    CLocalSocket m_server_sock;
+    OwnPtr<CNotifier> m_server_notifier;
 };