Kernel: Add KBuffer::try_create_with_bytes()

Here's another fallible KBuffer construction API that creates a KBuffer
and populates it with a range of bytes.

Kernel/KBuffer.h

@@ -56,6 +56,16 @@ class KBufferImpl : public RefCounted<KBufferImpl> {
  return adopt(*new KBufferImpl(region.release_nonnull(), size));
  }
 
+ static RefPtr<KBufferImpl> try_create_with_bytes(ReadonlyBytes bytes, u8 access, const char* name)
+ {
+ auto region = MM.allocate_kernel_region(PAGE_ROUND_UP(bytes.size()), name, access, false, false);
+ if (!region)
+ return nullptr;
+ if (!region->commit())
+ return nullptr;
+ return adopt(*new KBufferImpl(region.release_nonnull(), bytes.size()));
+ }
+
  static NonnullRefPtr<KBufferImpl> create_with_size(size_t size, u8 access, const char* name)
  {
  auto impl = try_create_with_size(size, access, name);
@@ -106,6 +116,14 @@ class KBuffer {
  return adopt_own(*new KBuffer(impl.release_nonnull()));
  }
 
+ static OwnPtr<KBuffer> try_create_with_bytes(ReadonlyBytes bytes, u8 access = Region::Access::Read | Region::Access::Write, const char* name = "KBuffer")
+ {
+ auto impl = KBufferImpl::try_create_with_bytes(bytes, access, name);
+ if (!impl)
+ return nullptr;
+ return adopt_own(*new KBuffer(impl.release_nonnull()));
+ }
+
  static KBuffer create_with_size(size_t size, u8 access = Region::Access::Read | Region::Access::Write, const char* name = "KBuffer")
  {
  return KBuffer(KBufferImpl::create_with_size(size, access, name));