Correct lexer handling of FormCalc identifiers

This makes the lexer stricter on valid characters for identifiers, and
conform to the grammar in the FormCalc spec. This should remove a
class of inputs that ClusterFuzz is attempting that are breaking later
stages of the transpile.

BUG: chromium:736234, pdfium:783, pdfium:784

Change-Id: I3987d6778a82b71d768fa751035993c0af2577ee
Reviewed-on: https://pdfium-review.googlesource.com/8010
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

1 files changed, 34 insertions, 1 deletions

diff --git a/xfa/fxfa/fm2js/cxfa_fmlexer_unittest.cpp b/xfa/fxfa/fm2js/cxfa_fmlexer_unittest.cpp
index 7ca12d2fad..5a8139d416 100644
--- a/xfa/fxfa/fm2js/cxfa_fmlexer_unittest.cpp
+++ b/xfa/fxfa/fm2js/cxfa_fmlexer_unittest.cpp
@@ -208,7 +208,7 @@ TEST(CXFA_FMLexerTest, Comments) {
   EXPECT_EQ(TOKeof, token->m_type);
 }
 
-TEST(CXFA_FMLexerTest, Identifiers) {
+TEST(CXFA_FMLexerTest, ValidIdentifiers) {
   std::vector<const wchar_t*> identifiers = {
       L"a", L"an_identifier", L"_ident", L"$ident", L"!ident", L"GetAddr"};
   for (const auto* ident : identifiers) {
@@ -219,6 +219,39 @@ TEST(CXFA_FMLexerTest, Identifiers) {
   }
 }
 
+TEST(CXFA_FMLexerTest, InvalidIdentifiers) {
+  auto lexer = pdfium::MakeUnique<CXFA_FMLexer>(L"#a");
+  lexer->NextToken();
+  // TODO(rharrison): Add an expects for the return being nullptr here.
+  // See https://crbug.com/pdfium/814
+  EXPECT_TRUE(lexer->HasError());
+
+  lexer = pdfium::MakeUnique<CXFA_FMLexer>(L"1a");
+  lexer->NextToken();
+  // TODO(rharrison): Add an expects for the return being nullptr here.
+  // See https://crbug.com/pdfium/814
+  EXPECT_TRUE(lexer->HasError());
+
+  lexer = pdfium::MakeUnique<CXFA_FMLexer>(L"an@identifier");
+  lexer->NextToken();
+  EXPECT_FALSE(lexer->HasError());
+  lexer->NextToken();
+  // TODO(rharrison): Add an expects for the return being nullptr here.
+  // See https://crbug.com/pdfium/814
+  EXPECT_TRUE(lexer->HasError());
+  // TODO(rharrison): Add a test for if an another call to NextToken occurs,
+  // the error state will be retained, instead of continuing the parse.
+  // See https://crbug.com/pdfium/814
+
+  lexer = pdfium::MakeUnique<CXFA_FMLexer>(L"_ident@");
+  lexer->NextToken();
+  EXPECT_FALSE(lexer->HasError());
+  lexer->NextToken();
+  // TODO(rharrison): Add an expects for the return being nullptr here.
+  // See https://crbug.com/pdfium/814
+  EXPECT_TRUE(lexer->HasError());
+}
+
 TEST(CXFA_FMLexerTest, Whitespace) {
   auto lexer = pdfium::MakeUnique<CXFA_FMLexer>(L" \t\xc\x9\xb");
   CXFA_FMToken* token = lexer->NextToken();