[llvm] [Object] Beginnings of SFrame parser and dumper (PR #147294)

[Pavel Labath via llvm-commits]

================
@@ -0,0 +1,56 @@
+//===- SFrameParser.cpp ---------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Object/SFrameParser.h"
+#include "llvm/BinaryFormat/SFrame.h"
+#include "llvm/Object/Error.h"
+#include "llvm/Support/FormatVariadic.h"
+
+using namespace llvm;
+using namespace llvm::object;
+
+template <typename T>
+static Expected<const T &> getDataSliceAs(ArrayRef<uint8_t> Data,
+                                          uint64_t Offset) {
+  static_assert(std::is_trivial_v<T>);
+  if (Data.size() < Offset + sizeof(T)) {
+    return make_error<GenericBinaryError>(
+        formatv("unexpected end of data at offset {0:x} while reading [{1:x}, "
+                "{2:x})",
+                Data.size(), Offset, Offset + sizeof(T))
+            .str(),
+        object_error::unexpected_eof);
+  }
+  return *reinterpret_cast<const T *>(Data.data() + Offset);
+}
+
+template <endianness E>
+Expected<SFrameParser<E>> SFrameParser<E>::create(ArrayRef<uint8_t> Contents) {
+  Expected<const sframe::Preamble<E> &> Preamble =
+      getDataSliceAs<sframe::Preamble<E>>(Contents, 0);
+  if (!Preamble)
+    return Preamble.takeError();
+
+  if (Preamble->Magic != sframe::Magic) {
+    return make_error<GenericBinaryError>("invalid magic number",
+                                          object_error::parse_failed);
----------------
labath wrote:

there's a createError in Object/Error.h, so I've used that.

https://github.com/llvm/llvm-project/pull/147294