[clang] Reject character devices in #embed for now

clang/docs/ReleaseNotes.rst

@@ -387,6 +387,9 @@ Bug Fixes in This Version
 
     #if 1 ? 1 : 999999999999999999999
     #endif
+- ``#embed`` directive now diagnoses use of a non-character file (device file)
+  such as ``/dev/urandom`` as an error. This restriction may be relaxed in the
+  future. See (#GH126629).
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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>;

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(); }
 

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) {

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) {

clang/test/Preprocessor/embed-reject-device-files-lin.c

@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -std=c23 %s -fsyntax-only -verify
+// REQUIRES: system-linux
+
+
+int urandom[] = {
+#embed "/dev/urandom" //expected-error {{device files are not yet supported by '#embed' directive}}
+};
+int random[] = {
+#embed "/dev/random" //expected-error {{device files are not yet supported by '#embed' directive}}
+};
+int zero[] = {
+#embed "/dev/zero" //expected-error {{device files are not yet supported by '#embed' directive}}
+};
+int null[] = {
+#embed "/dev/null" //expected-error {{device files are not yet supported by '#embed' directive}}
+};

clang/test/Preprocessor/embed-reject-device-files-win.c

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -std=c23 %s -fsyntax-only -verify
+// REQUIRES: system-windows
+
+
+int null[] = {
+#embed "NUL" limit(1) //expected-error {{device files are not yet supported by '#embed' directive}}
+};