LibCore+LibIPC: Add Core::AnonymousBuffer, an IPC-friendly buffer class

This will be used to migrate remaining clients off of shbufs.

Userland/Libraries/LibCore/AnonymousBuffer.cpp

@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibCore/AnonymousBuffer.h>
+#include <LibIPC/Decoder.h>
+#include <LibIPC/Encoder.h>
+#include <LibIPC/File.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/mman.h>
+
+#if defined(__serenity__)
+#    include <Kernel/API/Syscall.h>
+#    include <serenity.h>
+#endif
+
+namespace Core {
+
+AnonymousBuffer AnonymousBuffer::create_with_size(size_t size)
+{
+    int fd = -1;
+#if defined(__serenity__)
+    fd = anon_create(round_up_to_power_of_two(size, PAGE_SIZE), O_CLOEXEC);
+    if (fd < 0) {
+        perror("anon_create");
+        return {};
+    }
+#elif defined(__linux__)
+    fd = memfd_create("", MFD_CLOEXEC);
+    if (fd < 0) {
+        perror("memfd_create");
+        return {};
+    }
+    if (ftruncate(fd, size) < 0) {
+        perror("ftruncate");
+        return {};
+    }
+#endif
+    if (fd < 0)
+        return {};
+    return create_from_anon_fd(fd, size);
+}
+
+RefPtr<AnonymousBufferImpl> AnonymousBufferImpl::create(int fd, size_t size)
+{
+    auto* data = mmap(nullptr, round_up_to_power_of_two(size, PAGE_SIZE), PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0);
+    if (data == MAP_FAILED) {
+        perror("mmap");
+        return {};
+    }
+    return adopt(*new AnonymousBufferImpl(fd, size, data));
+}
+
+AnonymousBufferImpl::~AnonymousBufferImpl()
+{
+    if (m_fd != -1) {
+        auto rc = close(m_fd);
+        ASSERT(rc == 0);
+    }
+    auto rc = munmap(m_data, round_up_to_power_of_two(m_size, PAGE_SIZE));
+    ASSERT(rc == 0);
+}
+
+AnonymousBuffer AnonymousBuffer::create_from_anon_fd(int fd, size_t size)
+{
+    auto impl = AnonymousBufferImpl::create(fd, size);
+    if (!impl)
+        return {};
+    return AnonymousBuffer(impl.release_nonnull());
+}
+
+AnonymousBuffer::AnonymousBuffer(NonnullRefPtr<AnonymousBufferImpl> impl)
+    : m_impl(move(impl))
+{
+}
+
+AnonymousBufferImpl::AnonymousBufferImpl(int fd, size_t size, void* data)
+    : m_fd(fd)
+    , m_size(size)
+    , m_data(data)
+{
+}
+
+AnonymousBuffer::~AnonymousBuffer()
+{
+}
+
+}

Userland/Libraries/LibCore/AnonymousBuffer.h

@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Noncopyable.h>
+#include <AK/RefCounted.h>
+#include <AK/RefPtr.h>
+#include <AK/Types.h>
+#include <LibIPC/Forward.h>
+
+namespace Core {
+
+class AnonymousBufferImpl final : public RefCounted<AnonymousBufferImpl> {
+public:
+    static RefPtr<AnonymousBufferImpl> create(int fd, size_t);
+    ~AnonymousBufferImpl();
+
+    int fd() const { return m_fd; }
+    size_t size() const { return m_size; }
+    void* data() { return m_data; }
+    const void* data() const { return m_data; }
+
+private:
+    AnonymousBufferImpl(int fd, size_t, void*);
+
+    int m_fd { -1 };
+    size_t m_size { 0 };
+    void* m_data { nullptr };
+};
+
+class AnonymousBuffer {
+public:
+    static AnonymousBuffer create_with_size(size_t);
+    static AnonymousBuffer create_from_anon_fd(int fd, size_t);
+
+    AnonymousBuffer() { }
+    ~AnonymousBuffer();
+
+    bool is_valid() const { return m_impl; }
+
+    int fd() const { return m_impl ? m_impl->fd() : -1; }
+    size_t size() const { return m_impl ? m_impl->size() : 0; }
+
+    template<typename T>
+    T* data()
+    {
+        static_assert(IsVoid<T>::value || is_trivial<T>());
+        if (!m_impl)
+            return nullptr;
+        return (T*)m_impl->data();
+    }
+
+    template<typename T>
+    const T* data() const
+    {
+        static_assert(IsVoid<T>::value || is_trivial<T>());
+        if (!m_impl)
+            return nullptr;
+        return (const T*)m_impl->data();
+    }
+
+private:
+    explicit AnonymousBuffer(NonnullRefPtr<AnonymousBufferImpl>);
+
+    RefPtr<AnonymousBufferImpl> m_impl;
+};
+
+}
+
+namespace IPC {
+
+bool encode(Encoder&, const Core::AnonymousBuffer&);
+bool decode(Decoder&, Core::AnonymousBuffer&);
+
+}

Userland/Libraries/LibCore/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(SOURCES
     Account.cpp
+    AnonymousBuffer.cpp
     ArgsParser.cpp
     ConfigFile.cpp
     Command.cpp

Userland/Libraries/LibCore/Forward.h

@@ -28,6 +28,7 @@
 
 namespace Core {
 
+class AnonymousBuffer;
 class ArgsParser;
 class ChildEvent;
 class ConfigFile;

Userland/Libraries/LibIPC/Decoder.cpp

@@ -26,6 +26,7 @@
 
 #include <AK/MemoryStream.h>
 #include <AK/URL.h>
+#include <LibCore/AnonymousBuffer.h>
 #include <LibIPC/Decoder.h>
 #include <LibIPC/Dictionary.h>
 #include <LibIPC/File.h>
@@ -183,4 +184,24 @@ bool Decoder::decode([[maybe_unused]] File& file)
 #endif
 }
 
+bool decode(Decoder& decoder, Core::AnonymousBuffer& buffer)
+{
+    bool valid = false;
+    if (!decoder.decode(valid))
+        return false;
+    if (!valid) {
+        buffer = {};
+        return true;
+    }
+    u32 size;
+    if (!decoder.decode(size))
+        return false;
+    IPC::File anon_file;
+    if (!decoder.decode(anon_file))
+        return false;
+
+    buffer = Core::AnonymousBuffer::create_from_anon_fd(anon_file.take_fd(), size);
+    return buffer.is_valid();
+}
+
 }

Userland/Libraries/LibIPC/Encoder.cpp

@@ -27,6 +27,7 @@
 #include <AK/ByteBuffer.h>
 #include <AK/String.h>
 #include <AK/URL.h>
+#include <LibCore/AnonymousBuffer.h>
 #include <LibIPC/Dictionary.h>
 #include <LibIPC/Encoder.h>
 #include <LibIPC/File.h>
@@ -170,4 +171,13 @@ Encoder& Encoder::operator<<(const File& file)
     return *this;
 }
 
+bool encode(Encoder& encoder, const Core::AnonymousBuffer& buffer)
+{
+    encoder << buffer.is_valid();
+    if (buffer.is_valid()) {
+        encoder << (u32)buffer.size();
+        encoder << IPC::File(buffer.fd());
+    }
+    return true;
+}
 }