Add a simple /dev/full.

VirtualFileSystem/FullDevice.cpp

@@ -0,0 +1,30 @@
+#include "FullDevice.h"
+#include "Limits.h"
+#include "sys-errno.h"
+#include <AK/StdLib.h>
+#include <cstring>
+#include <cstdio>
+
+FullDevice::FullDevice()
+{
+}
+
+FullDevice::~FullDevice()
+{
+}
+
+ssize_t FullDevice::read(byte* buffer, size_t bufferSize)
+{
+    printf("read from full device\n");
+    size_t count = min(GoodBufferSize, bufferSize);
+    memset(buffer, 0, count);
+    return count;
+}
+
+ssize_t FullDevice::write(const byte*, size_t bufferSize)
+{
+    if (bufferSize == 0)
+        return 0;
+    return -ENOSPC;
+}
+