[readtapi] Setup simple stubify support (#76075)

Stubify broadly takes either tbd files or binary dylibs and turns them
into tbd files. In future patches, stubify will also allow additional
information to be embedded into the final TBD output too.

Add Util APIs to TextAPI for common operations used by readtapi for now. 

2 files changed, 41 insertions, 0 deletions

diff --git a/llvm/lib/TextAPI/CMakeLists.txt b/llvm/lib/TextAPI/CMakeLists.txt
index 2017a1ad..2953375 100644
--- a/llvm/lib/TextAPI/CMakeLists.txt
+++ b/llvm/lib/TextAPI/CMakeLists.txt
@@ -13,6 +13,7 @@ add_llvm_component_library(LLVMTextAPI
   TextAPIError.cpp
   TextStub.cpp
   TextStubCommon.cpp
+  Utils.cpp
 
   ADDITIONAL_HEADER_DIRS
   "${LLVM_MAIN_INCLUDE_DIR}/llvm/TextAPI"
diff --git a/llvm/lib/TextAPI/Utils.cpp b/llvm/lib/TextAPI/Utils.cpp
new file mode 100644
index 0000000..6d85083
--- /dev/null
+++ b/llvm/lib/TextAPI/Utils.cpp
@@ -0,0 +1,40 @@
+//===- Utils.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
+//
+//===----------------------------------------------------------------------===//
+//
+// Implements utility functions for TextAPI Darwin operations.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/TextAPI/Utils.h"
+
+using namespace llvm;
+using namespace llvm::MachO;
+
+void llvm::MachO::replace_extension(SmallVectorImpl<char> &Path,
+                                    const Twine &Extension) {
+  StringRef P(Path.begin(), Path.size());
+  auto ParentPath = sys::path::parent_path(P);
+  auto Filename = sys::path::filename(P);
+
+  if (!ParentPath.ends_with(Filename.str() + ".framework")) {
+    sys::path::replace_extension(Path, Extension);
+    return;
+  }
+  // Framework dylibs do not have a file extension, in those cases the new
+  // extension is appended. e.g. given Path: "Foo.framework/Foo" and Extension:
+  // "tbd", the result is "Foo.framework/Foo.tbd".
+  SmallString<8> Storage;
+  StringRef Ext = Extension.toStringRef(Storage);
+
+  // Append '.' if needed.
+  if (!Ext.empty() && Ext[0] != '.')
+    Path.push_back('.');
+
+  // Append extension.
+  Path.append(Ext.begin(), Ext.end());
+}