[Support] Explicitly detect recursive response files

Previous detection relied upon an arbitrary hard coded limit of 21
response files, which some code bases were running up against.

The new detection maintains a stack of processing response files and
explicitly checks if a newly encountered file is in the current stack.
Some bookkeeping data is necessary in order to detect when to pop the
stack.

Patch by Chris Glover.

Differential Revision: https://reviews.llvm.org/D62798

llvm-svn: 363005

llvm/lib/Support/CommandLine.cpp

@@ -1097,43 +1097,84 @@ static bool ExpandResponseFile(StringRef FName, StringSaver &Saver,
 bool cl::ExpandResponseFiles(StringSaver &Saver, TokenizerCallback Tokenizer,
                              SmallVectorImpl<const char *> &Argv,
                              bool MarkEOLs, bool RelativeNames) {
-  unsigned ExpandedRspFiles = 0;
   bool AllExpanded = true;
+  struct ResponseFileRecord {
+    const char *File;
+    size_t End;
+  };
+
+  // To detect recursive response files, we maintain a stack of files and the
+  // position of the last argument in the file. This position is updated
+  // dynamically as we recursively expand files.
+  SmallVector<ResponseFileRecord, 3> FileStack;
+
+  // Push a dummy entry that represents the initial command line, removing
+  // the need to check for an empty list.
+  FileStack.push_back({"", Argv.size()});
 
   // Don't cache Argv.size() because it can change.
   for (unsigned I = 0; I != Argv.size();) {
+    while (I == FileStack.back().End) {
+      // Passing the end of a file's argument list, so we can remove it from the
+      // stack.
+      FileStack.pop_back();
+    }
+
     const char *Arg = Argv[I];
     // Check if it is an EOL marker
     if (Arg == nullptr) {
       ++I;
       continue;
     }
+
     if (Arg[0] != '@') {
       ++I;
       continue;
     }
 
-    // If we have too many response files, leave some unexpanded.  This avoids
+    const char *FName = Arg + 1;
-    // crashing on self-referential response files.
+    auto IsEquivalent = [FName](const ResponseFileRecord &RFile) {
-    if (ExpandedRspFiles > 20)
+      return sys::fs::equivalent(RFile.File, FName);
-      return false;
+    };
+
+    // Check for recursive response files.
+    if (std::any_of(FileStack.begin() + 1, FileStack.end(), IsEquivalent)) {
+      // This file is recursive, so we leave it in the argument stream and
+      // move on.
+      AllExpanded = false;
+      ++I;
+      continue;
+    }
 
     // Replace this response file argument with the tokenization of its
     // contents.  Nested response files are expanded in subsequent iterations.
     SmallVector<const char *, 0> ExpandedArgv;
-    if (ExpandResponseFile(Arg + 1, Saver, Tokenizer, ExpandedArgv, MarkEOLs,
+    if (!ExpandResponseFile(FName, Saver, Tokenizer, ExpandedArgv, MarkEOLs,
                             RelativeNames)) {
-      ++ExpandedRspFiles;
-    } else {
       // We couldn't read this file, so we leave it in the argument stream and
       // move on.
       AllExpanded = false;
       ++I;
       continue;
     }
+
+    for (ResponseFileRecord &Record : FileStack) {
+      // Increase the end of all active records by the number of newly expanded
+      // arguments, minus the response file itself.
+      Record.End += ExpandedArgv.size() - 1;
+    }
+
+    FileStack.push_back({FName, I + ExpandedArgv.size()});
     Argv.erase(Argv.begin() + I);
     Argv.insert(Argv.begin() + I, ExpandedArgv.begin(), ExpandedArgv.end());
   }
+
+  // If successful, the top of the file stack will mark the end of the Argv
+  // stream. A failure here indicates a bug in the stack popping logic above.
+  // Note that FileStack may have more than one element at this point because we
+  // don't have a chance to pop the stack when encountering recursive files at
+  // the end of the stream, so seeing that doesn't indicate a bug.
+  assert(FileStack.size() > 0 && Argv.size() == FileStack.back().End);
   return AllExpanded;
 }
 

llvm/unittests/Support/CommandLineTest.cpp

@@ -790,7 +790,9 @@ TEST(CommandLineTest, ResponseFiles) {
   EXPECT_TRUE(IncludedFile.is_open());
   IncludedFile << "-option_1 -option_2\n"
                   "@incdir/resp2\n"
-                  "-option_3=abcd\n";
+                  "-option_3=abcd\n"
+                  "@incdir/resp3\n"
+                  "-option_4=efjk\n";
   IncludedFile.close();
 
   // Directory for included file.
@@ -808,6 +810,15 @@ TEST(CommandLineTest, ResponseFiles) {
   IncludedFile2 << "-option_23=abcd\n";
   IncludedFile2.close();
 
+  // Create second included response file of second level.
+  llvm::SmallString<128> IncludedFileName3;
+  llvm::sys::path::append(IncludedFileName3, IncDir, "resp3");
+  std::ofstream IncludedFile3(IncludedFileName3.c_str());
+  EXPECT_TRUE(IncludedFile3.is_open());
+  IncludedFile3 << "-option_31 -option_32\n";
+  IncludedFile3 << "-option_33=abcd\n";
+  IncludedFile3.close();
+
   // Prepare 'file' with reference to response file.
   SmallString<128> IncRef;
   IncRef.append(1, '@');
@@ -821,7 +832,7 @@ TEST(CommandLineTest, ResponseFiles) {
   bool Res = llvm::cl::ExpandResponseFiles(
                     Saver, llvm::cl::TokenizeGNUCommandLine, Argv, false, true);
   EXPECT_TRUE(Res);
-  EXPECT_EQ(Argv.size(), 9U);
+  EXPECT_EQ(Argv.size(), 13U);
   EXPECT_STREQ(Argv[0], "test/test");
   EXPECT_STREQ(Argv[1], "-flag_1");
   EXPECT_STREQ(Argv[2], "-option_1");
@@ -830,8 +841,13 @@ TEST(CommandLineTest, ResponseFiles) {
   EXPECT_STREQ(Argv[5], "-option_22");
   EXPECT_STREQ(Argv[6], "-option_23=abcd");
   EXPECT_STREQ(Argv[7], "-option_3=abcd");
-  EXPECT_STREQ(Argv[8], "-flag_2");
+  EXPECT_STREQ(Argv[8], "-option_31");
+  EXPECT_STREQ(Argv[9], "-option_32");
+  EXPECT_STREQ(Argv[10], "-option_33=abcd");
+  EXPECT_STREQ(Argv[11], "-option_4=efjk");
+  EXPECT_STREQ(Argv[12], "-flag_2");
 
+  llvm::sys::fs::remove(IncludedFileName3);
   llvm::sys::fs::remove(IncludedFileName2);
   llvm::sys::fs::remove(IncDir);
   llvm::sys::fs::remove(IncludedFileName);
@@ -843,18 +859,45 @@ TEST(CommandLineTest, RecursiveResponseFiles) {
   std::error_code EC = sys::fs::createUniqueDirectory("unittest", TestDir);
   EXPECT_TRUE(!EC);
 
-  SmallString<128> ResponseFilePath;
+  SmallString<128> SelfFilePath;
-  sys::path::append(ResponseFilePath, TestDir, "recursive.rsp");
+  sys::path::append(SelfFilePath, TestDir, "self.rsp");
-  std::string ResponseFileRef = std::string("@") + ResponseFilePath.c_str();
+  std::string SelfFileRef = std::string("@") + SelfFilePath.c_str();
 
-  std::ofstream ResponseFile(ResponseFilePath.str());
+  SmallString<128> NestedFilePath;
-  EXPECT_TRUE(ResponseFile.is_open());
+  sys::path::append(NestedFilePath, TestDir, "nested.rsp");
-  ResponseFile << ResponseFileRef << "\n";
+  std::string NestedFileRef = std::string("@") + NestedFilePath.c_str();
-  ResponseFile << ResponseFileRef << "\n";
-  ResponseFile.close();
 
-  // Ensure the recursive expansion terminates.
+  SmallString<128> FlagFilePath;
-  SmallVector<const char *, 4> Argv = {"test/test", ResponseFileRef.c_str()};
+  sys::path::append(FlagFilePath, TestDir, "flag.rsp");
+  std::string FlagFileRef = std::string("@") + FlagFilePath.c_str();
+
+  std::ofstream SelfFile(SelfFilePath.str());
+  EXPECT_TRUE(SelfFile.is_open());
+  SelfFile << "-option_1\n";
+  SelfFile << FlagFileRef << "\n";
+  SelfFile << NestedFileRef << "\n";
+  SelfFile << SelfFileRef << "\n";
+  SelfFile.close();
+
+  std::ofstream NestedFile(NestedFilePath.str());
+  EXPECT_TRUE(NestedFile.is_open());
+  NestedFile << "-option_2\n";
+  NestedFile << FlagFileRef << "\n";
+  NestedFile << SelfFileRef << "\n";
+  NestedFile << NestedFileRef << "\n";
+  NestedFile.close();
+
+  std::ofstream FlagFile(FlagFilePath.str());
+  EXPECT_TRUE(FlagFile.is_open());
+  FlagFile << "-option_x\n";
+  FlagFile.close();
+
+  // Ensure:
+  // Recursive expansion terminates
+  // Recursive files never expand
+  // Non-recursive repeats are allowed
+  SmallVector<const char *, 4> Argv = {"test/test", SelfFileRef.c_str(),
+                                       "-option_3"};
   BumpPtrAllocator A;
   StringSaver Saver(A);
 #ifdef _WIN32
@@ -865,11 +908,16 @@ TEST(CommandLineTest, RecursiveResponseFiles) {
   bool Res = cl::ExpandResponseFiles(Saver, Tokenizer, Argv, false, false);
   EXPECT_FALSE(Res);
 
-  // Ensure some expansion took place.
+  EXPECT_EQ(Argv.size(), 9U);
-  EXPECT_GT(Argv.size(), 2U);
   EXPECT_STREQ(Argv[0], "test/test");
-  for (size_t i = 1; i < Argv.size(); ++i)
+  EXPECT_STREQ(Argv[1], "-option_1");
-    EXPECT_STREQ(Argv[i], ResponseFileRef.c_str());
+  EXPECT_STREQ(Argv[2], "-option_x");
+  EXPECT_STREQ(Argv[3], "-option_2");
+  EXPECT_STREQ(Argv[4], "-option_x");
+  EXPECT_STREQ(Argv[5], SelfFileRef.c_str());
+  EXPECT_STREQ(Argv[6], NestedFileRef.c_str());
+  EXPECT_STREQ(Argv[7], SelfFileRef.c_str());
+  EXPECT_STREQ(Argv[8], "-option_3");
 }
 
 TEST(CommandLineTest, ResponseFilesAtArguments) {