[InstallAPI] Cleanup I/O error handling for input lists (#90664)

Add validation in the FileList reader to check that the headers exist and use similar diagnostics in Options.cpp

Author: cyndyishida

clang/include/clang/Basic/DiagnosticInstallAPIKinds.td

@@ -24,7 +24,7 @@ def err_no_matching_target : Error<"no matching target found for target variant
 def err_unsupported_vendor : Error<"vendor '%0' is not supported: '%1'">;
 def err_unsupported_environment : Error<"environment '%0' is not supported: '%1'">;
 def err_unsupported_os : Error<"os '%0' is not supported: '%1'">;
-def err_cannot_read_alias_list : Error<"could not read alias list '%0': %1">;
+def err_cannot_read_input_list : Error<"could not read %select{alias list|filelist}0 '%1': %2">;
 } // end of command line category.
 
 let CategoryName = "Verification" in {

clang/include/clang/InstallAPI/FileList.h

@@ -29,9 +29,10 @@ class FileListReader {
   ///
   /// \param InputBuffer JSON input data.
   /// \param Destination Container to load headers into.
+  /// \param FM Optional File Manager to validate input files exist.
   static llvm::Error
   loadHeaders(std::unique_ptr<llvm::MemoryBuffer> InputBuffer,
-              HeaderSeq &Destination);
+              HeaderSeq &Destination, clang::FileManager *FM = nullptr);
 
   FileListReader() = delete;
 };

clang/lib/InstallAPI/FileList.cpp

@@ -51,6 +51,7 @@ class Implementation {
 
 public:
   std::unique_ptr<MemoryBuffer> InputBuffer;
+  clang::FileManager *FM;
   unsigned Version;
   HeaderSeq HeaderList;
 
@@ -124,6 +125,12 @@ Error Implementation::parseHeaders(Array &Headers) {
           HeaderFile{PathStr, *Type, /*IncludeName=*/"", Language});
       continue;
     }
+
+    if (FM)
+      if (!FM->getOptionalFileRef(PathStr))
+        return createFileError(
+            PathStr, make_error_code(std::errc::no_such_file_or_directory));
+
     auto IncludeName = createIncludeHeaderName(PathStr);
     HeaderList.emplace_back(PathStr, *Type,
                             IncludeName.has_value() ? IncludeName.value() : "",
@@ -170,9 +177,10 @@ Error Implementation::parse(StringRef Input) {
 
 llvm::Error
 FileListReader::loadHeaders(std::unique_ptr<MemoryBuffer> InputBuffer,
-                            HeaderSeq &Destination) {
+                            HeaderSeq &Destination, clang::FileManager *FM) {
   Implementation Impl;
   Impl.InputBuffer = std::move(InputBuffer);
+  Impl.FM = FM;
 
   if (llvm::Error Err = Impl.parse(Impl.InputBuffer->getBuffer()))
     return Err;

clang/tools/clang-installapi/Options.cpp

@@ -697,8 +697,8 @@ InstallAPIContext Options::createContext() {
     }
     Expected<AliasMap> Result = parseAliasList(Buffer.get());
     if (!Result) {
-      Diags->Report(diag::err_cannot_read_alias_list)
-          << ListPath << toString(Result.takeError());
+      Diags->Report(diag::err_cannot_read_input_list)
+          << /*IsFileList=*/false << ListPath << toString(Result.takeError());
       return Ctx;
     }
     Aliases.insert(Result.get().begin(), Result.get().end());
@@ -717,8 +717,9 @@ InstallAPIContext Options::createContext() {
       return Ctx;
     }
     if (auto Err = FileListReader::loadHeaders(std::move(Buffer.get()),
-                                               Ctx.InputHeaders)) {
-      Diags->Report(diag::err_cannot_open_file) << ListPath << std::move(Err);
+                                               Ctx.InputHeaders, FM)) {
+      Diags->Report(diag::err_cannot_read_input_list)
+          << /*IsFileList=*/true << ListPath << std::move(Err);
       return Ctx;
     }
   }