[clang] [llvm] [llvm][clang] Sandbox filesystem reads (PR #165350)

[Ben Langmuir via llvm-commits]

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@@ -347,12 +348,15 @@ llvm::Expected<FileEntryRef> FileManager::getSTDIN() {
   if (STDIN)
     return *STDIN;
 
-  std::unique_ptr<llvm::MemoryBuffer> Content;
-  if (auto ContentOrError = llvm::MemoryBuffer::getSTDIN())
-    Content = std::move(*ContentOrError);
-  else
+  auto ContentOrError = [] {
+    auto BypassSandbox = llvm::sys::sandbox::scopedDisable();
+    return llvm::MemoryBuffer::getSTDIN();
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benlangmuir wrote:

What's the intent for stdin in general? From a VFS perspective there is no problem with opening stdin, because it's not affected by the VFS anyway.  From a caching/cas perspective you need to prevent or capture it somehow, but the VFS won't help you do so.

https://github.com/llvm/llvm-project/pull/165350