[clang] [clang] Reject character devices in #embed for now (PR #135370)

[Mariya Podchishchaeva via cfe-commits]

https://github.com/Fznamznon created https://github.com/llvm/llvm-project/pull/135370

See https://github.com/llvm/llvm-project/issues/126629 . Right not they are not supported properly and support requires modifying several layers of LLVM. For now simply reject them while proper support is being developed to avoid potential security problems.

>From 49e347a73709661fcf3a4805f38cfa2d78e3a196 Mon Sep 17 00:00:00 2001
From: "Podchishchaeva, Mariya" <mariya.podchishchaeva at intel.com>
Date: Fri, 11 Apr 2025 06:46:00 -0700
Subject: [PATCH] [clang] Reject character devices in #embed for now

See https://github.com/llvm/llvm-project/issues/126629 .
Right not they are not supported properly and support requires modifying
several layers of LLVM. For now simply reject them while proper support
is being developed to avoid potential security problems.
---
 clang/include/clang/Basic/DiagnosticLexKinds.td | 2 ++
 clang/include/clang/Basic/FileEntry.h           | 6 ++++++
 clang/lib/Basic/FileManager.cpp                 | 2 ++
 clang/lib/Lex/PPDirectives.cpp                  | 6 ++++++
 4 files changed, 16 insertions(+)

diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index 912b8bd46e194..f29edfa835d42 100644
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -458,6 +458,8 @@ def warn_compat_pp_embed_directive : Warning<
   InGroup<CPre23Compat>, DefaultIgnore;
 def err_pp_embed_dup_params : Error<
   "cannot specify parameter '%0' twice in the same '#embed' directive">;
+def err_pp_embed_device_file : Error<
+  "device files are not yet supported by '#embed' directive">;
 
 def ext_pp_extra_tokens_at_eol : ExtWarn<
   "extra tokens at end of #%0 directive">, InGroup<ExtraTokens>;
diff --git a/clang/include/clang/Basic/FileEntry.h b/clang/include/clang/Basic/FileEntry.h
index da5ba90974293..c973ba38bdf7e 100644
--- a/clang/include/clang/Basic/FileEntry.h
+++ b/clang/include/clang/Basic/FileEntry.h
@@ -82,6 +82,7 @@ class FileEntryRef {
   inline const llvm::sys::fs::UniqueID &getUniqueID() const;
   inline time_t getModificationTime() const;
   inline bool isNamedPipe() const;
+  inline bool isDeviceFile() const;
   inline void closeFile() const;
 
   /// Check if the underlying FileEntry is the same, intentially ignoring
@@ -316,6 +317,7 @@ class FileEntry {
   llvm::sys::fs::UniqueID UniqueID;
   unsigned UID = 0; // A unique (small) ID for the file.
   bool IsNamedPipe = false;
+  bool IsDeviceFile = false;
 
   /// The open file, if it is owned by the \p FileEntry.
   mutable std::unique_ptr<llvm::vfs::File> File;
@@ -340,6 +342,7 @@ class FileEntry {
   /// Check whether the file is a named pipe (and thus can't be opened by
   /// the native FileManager methods).
   bool isNamedPipe() const { return IsNamedPipe; }
+  bool isDeviceFile() const { return IsDeviceFile; }
 
   void closeFile() const;
 };
@@ -357,6 +360,9 @@ time_t FileEntryRef::getModificationTime() const {
 }
 
 bool FileEntryRef::isNamedPipe() const { return getFileEntry().isNamedPipe(); }
+bool FileEntryRef::isDeviceFile() const {
+  return getFileEntry().isDeviceFile();
+}
 
 void FileEntryRef::closeFile() const { getFileEntry().closeFile(); }
 
diff --git a/clang/lib/Basic/FileManager.cpp b/clang/lib/Basic/FileManager.cpp
index ec84aad72e6be..86fe352df0461 100644
--- a/clang/lib/Basic/FileManager.cpp
+++ b/clang/lib/Basic/FileManager.cpp
@@ -330,6 +330,8 @@ llvm::Expected<FileEntryRef> FileManager::getFileRef(StringRef Filename,
   UFE->UID = NextFileUID++;
   UFE->UniqueID = Status.getUniqueID();
   UFE->IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
+  UFE->IsDeviceFile =
+      Status.getType() == llvm::sys::fs::file_type::character_file;
   UFE->File = std::move(F);
 
   if (UFE->File) {
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index d97a6e8d64f9c..318b8fdad2e04 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -4010,6 +4010,12 @@ void Preprocessor::HandleEmbedDirective(SourceLocation HashLoc, Token &EmbedTok,
     Diag(FilenameTok, diag::err_pp_file_not_found) << Filename;
     return;
   }
+
+  if (MaybeFileRef->isDeviceFile()) {
+    Diag(FilenameTok, diag::err_pp_embed_device_file) << Filename;
+    return;
+  }
+
   std::optional<llvm::MemoryBufferRef> MaybeFile =
       getSourceManager().getMemoryBufferForFileOrNone(*MaybeFileRef);
   if (!MaybeFile) {