[clang] [llvm] [clang] Use the VFS in `CrossTranslationUnitContext` (PR #175097)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Jan Svoboda (jansvoboda11)

<details>
<summary>Changes</summary>

This PR propagates the VFS where necessary from `CrossTranslationUnitContext::ASTLoader` to avoid sandbox violations.

---
Full diff: https://github.com/llvm/llvm-project/pull/175097.diff


1 Files Affected:

- (modified) clang/lib/CrossTU/CrossTranslationUnit.cpp (+4-1) 


``````````diff
diff --git a/clang/lib/CrossTU/CrossTranslationUnit.cpp b/clang/lib/CrossTU/CrossTranslationUnit.cpp
index a3fc2cf6bfb3c..7496deb74cb67 100644
--- a/clang/lib/CrossTU/CrossTranslationUnit.cpp
+++ b/clang/lib/CrossTU/CrossTranslationUnit.cpp
@@ -24,6 +24,7 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/IOSandbox.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/YAMLParser.h"
@@ -620,6 +621,8 @@ CrossTranslationUnitContext::ASTLoader::loadFromSource(
   auto Diags = llvm::makeIntrusiveRefCnt<DiagnosticsEngine>(DiagID, *DiagOpts,
                                                             DiagClient);
 
+  // This runs the driver which isn't expected to be free of sandbox violations.
+  auto BypassSandbox = llvm::sys::sandbox::scopedDisable();
   return CreateASTUnitFromCommandLine(
       CommandLineArgs.begin(), (CommandLineArgs.end()),
       CI.getPCHContainerOperations(), DiagOpts, Diags,
@@ -710,7 +713,7 @@ llvm::Error CrossTranslationUnitContext::ASTLoader::lazyInitInvocationList() {
     return llvm::make_error<IndexError>(PreviousParsingResult);
 
   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> FileContent =
-      llvm::MemoryBuffer::getFile(InvocationListFilePath);
+      CI.getVirtualFileSystem().getBufferForFile(InvocationListFilePath);
   if (!FileContent) {
     PreviousParsingResult = index_error_code::invocation_list_file_not_found;
     return llvm::make_error<IndexError>(PreviousParsingResult);

``````````

</details>


https://github.com/llvm/llvm-project/pull/175097