[Support] Beef up and expose the response file parsing in llvm::cl

The plan is to use it for clang and lld.

Major behavior changes:
- We can now parse UTF-16 files that have a byte order mark.
- PR16209: Don't drop backslashes on the floor if they don't escape
  anything.

The actual parsing loop was based on code from Clang's driver.cpp,
although it's been rewritten to track its state with control flow rather
than state variables.

Reviewers: hans

Differential Revision: http://llvm-reviews.chandlerc.com/D1170

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186587 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 224 insertions, 64 deletions

diff --git a/include/llvm/Support/CommandLine.h b/include/llvm/Support/CommandLine.h
index 531760b..8fb4630 100644
--- a/include/llvm/Support/CommandLine.h
+++ b/include/llvm/Support/CommandLine.h
@@ -1745,6 +1745,59 @@ void PrintHelpMessage(bool Hidden=false, bool Categorized=false);
 /// llvm::cl::ParseCommandLineOptions().
 void getRegisteredOptions(StringMap<Option*> &Map);
 
+//===----------------------------------------------------------------------===//
+// Standalone command line processing utilities.
+//
+
+/// \brief Saves strings in the inheritor's stable storage and returns a stable
+/// raw character pointer.
+class StringSaver {
+public:
+  virtual const char *SaveString(const char *Str) = 0;
+  virtual ~StringSaver() {};  // Pacify -Wnon-virtual-dtor.
+};
+
+/// \brief Tokenizes a command line that can contain escapes and quotes.
+//
+/// The quoting rules match those used by GCC and other tools that use
+/// libiberty's buildargv() or expandargv() utilities, and do not match bash.
+/// They differ from buildargv() on treatment of backslashes that do not escape
+/// a special character to make it possible to accept most Windows file paths.
+///
+/// \param [in] Source The string to be split on whitespace with quotes.
+/// \param [in] Saver Delegates back to the caller for saving parsed strings.
+/// \param [out] NewArgv All parsed strings are appended to NewArgv.
+void TokenizeGNUCommandLine(StringRef Source, StringSaver &Saver,
+                            SmallVectorImpl<const char *> &NewArgv);
+
+/// \brief Tokenizes a Windows command line which may contain quotes and escaped
+/// quotes.
+///
+/// See MSDN docs for CommandLineToArgvW for information on the quoting rules.
+/// http://msdn.microsoft.com/en-us/library/windows/desktop/17w5ykft(v=vs.85).aspx
+///
+/// \param [in] Source The string to be split on whitespace with quotes.
+/// \param [in] Saver Delegates back to the caller for saving parsed strings.
+/// \param [out] NewArgv All parsed strings are appended to NewArgv.
+void TokenizeWindowsCommandLine(StringRef Source, StringSaver &Saver,
+                                SmallVectorImpl<const char *> &NewArgv);
+
+/// \brief String tokenization function type.  Should be compatible with either
+/// Windows or Unix command line tokenizers.
+typedef void (*TokenizerCallback)(StringRef Source, StringSaver &Saver,
+                                  SmallVectorImpl<const char *> &NewArgv);
+
+/// \brief Expand response files on a command line recursively using the given
+/// StringSaver and tokenization strategy.  Argv should contain the command line
+/// before expansion and will be modified in place.
+///
+/// \param [in] Saver Delegates back to the caller for saving parsed strings.
+/// \param [in] Tokenize Tokenization strategy. Typically Unix or Windows.
+/// \param [in,out] Argv Command line into which to expand response files.
+/// \return true if all @files were expanded successfully or there were none.
+bool ExpandResponseFiles(StringSaver &Saver, TokenizerCallback Tokenizer,
+                         SmallVectorImpl<const char *> &Argv);
+
 } // End namespace cl
 
 } // End namespace llvm
diff --git a/lib/Support/CommandLine.cpp b/lib/Support/CommandLine.cpp
index 6ab03dc..c2a25a1 100644
--- a/lib/Support/CommandLine.cpp
+++ b/lib/Support/CommandLine.cpp
@@ -17,12 +17,14 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/CommandLine.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Config/config.h"
+#include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Host.h"
@@ -434,39 +436,137 @@ static bool EatsUnboundedNumberOfValues(const Option *O) {
          O->getNumOccurrencesFlag() == cl::OneOrMore;
 }
 
-/// ParseCStringVector - Break INPUT up wherever one or more
-/// whitespace characters are found, and store the resulting tokens in
-/// OUTPUT. The tokens stored in OUTPUT are dynamically allocated
-/// using strdup(), so it is the caller's responsibility to free()
-/// them later.
-///
-static void ParseCStringVector(std::vector<char *> &OutputVector,
-                               const char *Input) {
-  // Characters which will be treated as token separators:
-  StringRef Delims = " \v\f\t\r\n";
-
-  StringRef WorkStr(Input);
-  while (!WorkStr.empty()) {
-    // If the first character is a delimiter, strip them off.
-    if (Delims.find(WorkStr[0]) != StringRef::npos) {
-      size_t Pos = WorkStr.find_first_not_of(Delims);
-      if (Pos == StringRef::npos) Pos = WorkStr.size();
-      WorkStr = WorkStr.substr(Pos);
+static bool isWhitespace(char C) {
+  return strchr(" \t\n\r\f\v", C);
+}
+
+static bool isQuote(char C) {
+  return C == '\"' || C == '\'';
+}
+
+static bool isGNUSpecial(char C) {
+  return strchr("\\\"\' ", C);
+}
+
+void cl::TokenizeGNUCommandLine(StringRef Src, StringSaver &Saver,
+                                SmallVectorImpl<const char *> &NewArgv) {
+  SmallString<128> Token;
+  for (size_t I = 0, E = Src.size(); I != E; ++I) {
+    // Consume runs of whitespace.
+    if (Token.empty()) {
+      while (I != E && isWhitespace(Src[I]))
+        ++I;
+      if (I == E) break;
+    }
+
+    // Backslashes can escape backslashes, spaces, and other quotes.  Otherwise
+    // they are literal.  This makes it much easier to read Windows file paths.
+    if (I + 1 < E && Src[I] == '\\' && isGNUSpecial(Src[I + 1])) {
+      ++I;  // Skip the escape.
+      Token.push_back(Src[I]);
       continue;
     }
 
-    // Find position of first delimiter.
-    size_t Pos = WorkStr.find_first_of(Delims);
-    if (Pos == StringRef::npos) Pos = WorkStr.size();
+    // Consume a quoted string.
+    if (isQuote(Src[I])) {
+      char Quote = Src[I++];
+      while (I != E && Src[I] != Quote) {
+        // Backslashes are literal, unless they escape a special character.
+        if (Src[I] == '\\' && I + 1 != E && isGNUSpecial(Src[I + 1]))
+          ++I;
+        Token.push_back(Src[I]);
+        ++I;
+      }
+      if (I == E) break;
+      continue;
+    }
 
-    // Everything from 0 to Pos is the next word to copy.
-    char *NewStr = (char*)malloc(Pos+1);
-    memcpy(NewStr, WorkStr.data(), Pos);
-    NewStr[Pos] = 0;
-    OutputVector.push_back(NewStr);
+    // End the token if this is whitespace.
+    if (isWhitespace(Src[I])) {
+      if (!Token.empty())
+        NewArgv.push_back(Saver.SaveString(Token.c_str()));
+      Token.clear();
+      continue;
+    }
 
-    WorkStr = WorkStr.substr(Pos);
+    // This is a normal character.  Append it.
+    Token.push_back(Src[I]);
   }
+
+  // Append the last token after hitting EOF with no whitespace.
+  if (!Token.empty())
+    NewArgv.push_back(Saver.SaveString(Token.c_str()));
+}
+
+void cl::TokenizeWindowsCommandLine(StringRef Src, StringSaver &Saver,
+                                    SmallVectorImpl<const char *> &NewArgv) {
+  llvm_unreachable("FIXME not implemented");
+}
+
+static bool ExpandResponseFile(const char *FName, StringSaver &Saver,
+                               TokenizerCallback Tokenizer,
+                               SmallVectorImpl<const char *> &NewArgv) {
+  OwningPtr<MemoryBuffer> MemBuf;
+  if (MemoryBuffer::getFile(FName, MemBuf))
+    return false;
+  StringRef Str(MemBuf->getBufferStart(), MemBuf->getBufferSize());
+
+  // If we have a UTF-16 byte order mark, convert to UTF-8 for parsing.
+  ArrayRef<char> BufRef(MemBuf->getBufferStart(), MemBuf->getBufferEnd());
+  std::string UTF8Buf;
+  if (hasUTF16ByteOrderMark(BufRef)) {
+    if (!convertUTF16ToUTF8String(BufRef, UTF8Buf))
+      return false;
+    Str = StringRef(UTF8Buf);
+  }
+
+  // Tokenize the contents into NewArgv.
+  Tokenizer(Str, Saver, NewArgv);
+
+  return true;
+}
+
+/// \brief Expand response files on a command line recursively using the given
+/// StringSaver and tokenization strategy.
+bool cl::ExpandResponseFiles(StringSaver &Saver, TokenizerCallback Tokenizer,
+                             SmallVectorImpl<const char *> &Argv) {
+  unsigned RspFiles = 0;
+  bool AllExpanded = false;
+
+  // Don't cache Argv.size() because it can change.
+  for (unsigned I = 0; I != Argv.size(); ) {
+    const char *Arg = Argv[I];
+    if (Arg[0] != '@') {
+      ++I;
+      continue;
+    }
+
+    // If we have too many response files, leave some unexpanded.  This avoids
+    // crashing on self-referential response files.
+    if (RspFiles++ > 20)
+      return false;
+
+    // Replace this response file argument with the tokenization of its
+    // contents.  Nested response files are expanded in subsequent iterations.
+    // FIXME: If a nested response file uses a relative path, is it relative to
+    // the cwd of the process or the response file?
+    SmallVector<const char *, 0> ExpandedArgv;
+    if (!ExpandResponseFile(Arg + 1, Saver, Tokenizer, ExpandedArgv)) {
+      AllExpanded = false;
+      continue;
+    }
+    Argv.erase(Argv.begin() + I);
+    Argv.insert(Argv.begin() + I, ExpandedArgv.begin(), ExpandedArgv.end());
+  }
+  return AllExpanded;
+}
+
+namespace {
+  class StrDupSaver : public StringSaver {
+    const char *SaveString(const char *Str) LLVM_OVERRIDE {
+      return strdup(Str);
+    }
+  };
 }
 
 /// ParseEnvironmentOptions - An alternative entry point to the
@@ -487,45 +587,21 @@ void cl::ParseEnvironmentOptions(const char *progName, const char *envVar,
 
   // Get program's "name", which we wouldn't know without the caller
   // telling us.
-  std::vector<char*> newArgv;
+  SmallVector<const char *, 20> newArgv;
   newArgv.push_back(strdup(progName));
 
   // Parse the value of the environment variable into a "command line"
   // and hand it off to ParseCommandLineOptions().
-  ParseCStringVector(newArgv, envValue);
+  StrDupSaver Saver;
+  TokenizeGNUCommandLine(envValue, Saver, newArgv);
   int newArgc = static_cast<int>(newArgv.size());
   ParseCommandLineOptions(newArgc, &newArgv[0], Overview);
 
   // Free all the strdup()ed strings.
-  for (std::vector<char*>::iterator i = newArgv.begin(), e = newArgv.end();
+  for (SmallVectorImpl<const char *>::iterator i = newArgv.begin(),
+                                               e = newArgv.end();
        i != e; ++i)
-    free(*i);
-}
-
-
-/// ExpandResponseFiles - Copy the contents of argv into newArgv,
-/// substituting the contents of the response files for the arguments
-/// of type @file.
-static void ExpandResponseFiles(unsigned argc, const char*const* argv,
-                                std::vector<char*>& newArgv) {
-  for (unsigned i = 1; i != argc; ++i) {
-    const char *arg = argv[i];
-
-    if (arg[0] == '@') {
-      // TODO: we should also support recursive loading of response files,
-      // since this is how gcc behaves. (From their man page: "The file may
-      // itself contain additional @file options; any such options will be
-      // processed recursively.")
-
-      // Mmap the response file into memory.
-      OwningPtr<MemoryBuffer> respFilePtr;
-      if (!MemoryBuffer::getFile(arg + 1, respFilePtr)) {
-        ParseCStringVector(newArgv, respFilePtr->getBufferStart());
-        continue;
-      }
-    }
-    newArgv.push_back(strdup(arg));
-  }
+    free(const_cast<char *>(*i));
 }
 
 void cl::ParseCommandLineOptions(int argc, const char * const *argv,
@@ -540,9 +616,11 @@ void cl::ParseCommandLineOptions(int argc, const char * const *argv,
          "No options specified!");
 
   // Expand response files.
-  std::vector<char*> newArgv;
-  newArgv.push_back(strdup(argv[0]));
-  ExpandResponseFiles(argc, argv, newArgv);
+  SmallVector<const char *, 20> newArgv;
+  for (int i = 0; i != argc; ++i)
+    newArgv.push_back(strdup(argv[i]));
+  StrDupSaver Saver;
+  ExpandResponseFiles(Saver, TokenizeGNUCommandLine, newArgv);
   argv = &newArgv[0];
   argc = static_cast<int>(newArgv.size());
 
@@ -838,9 +916,10 @@ void cl::ParseCommandLineOptions(int argc, const char * const *argv,
 
   // Free the memory allocated by ExpandResponseFiles.
   // Free all the strdup()ed strings.
-  for (std::vector<char*>::iterator i = newArgv.begin(), e = newArgv.end();
+  for (SmallVectorImpl<const char *>::iterator i = newArgv.begin(),
+                                               e = newArgv.end();
        i != e; ++i)
-    free(*i);
+    free(const_cast<char *>(*i));
 
   // If we had an error processing our arguments, don't let the program execute
   if (ErrorParsing) exit(1);
diff --git a/test/Other/ResponseFile.ll b/test/Other/ResponseFile.ll
index b8b3d0a..914e548 100644
--- a/test/Other/ResponseFile.ll
+++ b/test/Other/ResponseFile.ll
@@ -1,5 +1,9 @@
-; RUN: echo %s > %t.list
-; RUN: llvm-as @%t.list -o %t.bc
+; Test that we can recurse, at least a little bit.  The -time-passes flag here
+; is a hack to make sure that neither echo nor the shell expands the response
+; file for us.  Tokenization with quotes is tested in unittests.
+; RUN: echo %s > %t.list1
+; RUN: echo "-time-passes @%t.list1" > %t.list2
+; RUN: llvm-as @%t.list2 -o %t.bc
 ; RUN: llvm-nm %t.bc 2>&1 | FileCheck %s
 
 ; CHECK: T foobar
diff --git a/unittests/Support/CommandLineTest.cpp b/unittests/Support/CommandLineTest.cpp
index cd235d2..7a1c382 100644
--- a/unittests/Support/CommandLineTest.cpp
+++ b/unittests/Support/CommandLineTest.cpp
@@ -7,6 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Config/config.h"
 #include "gtest/gtest.h"
@@ -118,4 +119,27 @@ TEST(CommandLineTest, UseOptionCategory) {
                                                   "Category.";
 }
 
+class StrDupSaver : public cl::StringSaver {
+  const char *SaveString(const char *Str) LLVM_OVERRIDE {
+    return strdup(Str);
+  }
+};
+
+TEST(CommandLineTest, TokenizeGNUCommandLine) {
+  const char *Input = "foo\\ bar \"foo bar\" \'foo bar\' 'foo\\\\bar' "
+                      "foo\"bar\"baz C:\\src\\foo.cpp \"C:\\src\\foo.cpp\"";
+  const char *const Output[] = { "foo bar", "foo bar", "foo bar", "foo\\bar",
+                                 "foobarbaz", "C:\\src\\foo.cpp",
+                                 "C:\\src\\foo.cpp" };
+  SmallVector<const char *, 0> Actual;
+  StrDupSaver Saver;
+  cl::TokenizeGNUCommandLine(Input, Saver, Actual);
+  EXPECT_EQ(array_lengthof(Output), Actual.size());
+  for (unsigned I = 0, E = Actual.size(); I != E; ++I) {
+    if (I < array_lengthof(Output))
+      EXPECT_STREQ(Output[I], Actual[I]);
+    free(const_cast<char *>(Actual[I]));
+  }
+}
+
 }  // anonymous namespace