AK: Move the userspace SharedBuffer from LibC to AK

This always felt out-of-place in LibC.

AK/SharedBuffer.cpp

@@ -0,0 +1,97 @@
+#include <AK/SharedBuffer.h>
+#include <AK/kmalloc.h>
+#include <Kernel/Syscall.h>
+#include <stdio.h>
+#include <unistd.h>
+
+namespace AK {
+
+RefPtr<SharedBuffer> SharedBuffer::create_with_size(int size)
+{
+    void* data;
+    int shared_buffer_id = create_shared_buffer(size, &data);
+    if (shared_buffer_id < 0) {
+        perror("create_shared_buffer");
+        return nullptr;
+    }
+    return adopt(*new SharedBuffer(shared_buffer_id, size, data));
+}
+
+bool SharedBuffer::share_with(pid_t peer)
+{
+    int ret = share_buffer_with(shared_buffer_id(), peer);
+    if (ret < 0) {
+        perror("share_buffer_with");
+        return false;
+    }
+    return true;
+}
+
+bool SharedBuffer::share_globally()
+{
+    int ret = share_buffer_globally(shared_buffer_id());
+    if (ret < 0) {
+        perror("share_buffer_globally");
+        return false;
+    }
+    return true;
+}
+
+RefPtr<SharedBuffer> SharedBuffer::create_from_shared_buffer_id(int shared_buffer_id)
+{
+    void* data = get_shared_buffer(shared_buffer_id);
+    if (data == (void*)-1) {
+        perror("get_shared_buffer");
+        return nullptr;
+    }
+    int size = get_shared_buffer_size(shared_buffer_id);
+    if (size < 0) {
+        perror("get_shared_buffer_size");
+        return nullptr;
+    }
+    return adopt(*new SharedBuffer(shared_buffer_id, size, data));
+}
+
+SharedBuffer::SharedBuffer(int shared_buffer_id, int size, void* data)
+    : m_shared_buffer_id(shared_buffer_id)
+    , m_size(size)
+    , m_data(data)
+{
+}
+
+SharedBuffer::~SharedBuffer()
+{
+    if (m_shared_buffer_id >= 0) {
+        int rc = release_shared_buffer(m_shared_buffer_id);
+        if (rc < 0) {
+            perror("release_shared_buffer");
+        }
+    }
+}
+
+void SharedBuffer::seal()
+{
+    int rc = seal_shared_buffer(m_shared_buffer_id);
+    if (rc < 0) {
+        perror("seal_shared_buffer");
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void SharedBuffer::set_volatile()
+{
+    u32 rc = syscall(SC_set_shared_buffer_volatile, m_shared_buffer_id, true);
+    ASSERT(rc == 0);
+}
+
+bool SharedBuffer::set_nonvolatile()
+{
+    u32 rc = syscall(SC_set_shared_buffer_volatile, m_shared_buffer_id, false);
+    if (rc == 0)
+        return true;
+    if (rc == 1)
+        return false;
+    ASSERT_NOT_REACHED();
+}
+
+}

AK/SharedBuffer.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <AK/RefCounted.h>
+#include <AK/RefPtr.h>
+
+namespace AK {
+
+class SharedBuffer : public RefCounted<SharedBuffer> {
+public:
+    static RefPtr<SharedBuffer> create_with_size(int);
+    static RefPtr<SharedBuffer> create_from_shared_buffer_id(int);
+    ~SharedBuffer();
+
+    bool share_globally();
+    bool share_with(pid_t);
+    int shared_buffer_id() const { return m_shared_buffer_id; }
+    void seal();
+    int size() const { return m_size; }
+    void* data() { return m_data; }
+    const void* data() const { return m_data; }
+    void set_volatile();
+    [[nodiscard]] bool set_nonvolatile();
+
+private:
+    SharedBuffer(int shared_buffer_id, int size, void*);
+
+    int m_shared_buffer_id { -1 };
+    int m_size { 0 };
+    void* m_data;
+};
+
+}
+
+using AK::SharedBuffer;