Merge to XFA: Exit infinite loops for cross reference loading

When cross reference sections form a loop, our code will enter an
infinite loop. Add detection and exit code for v4 cross reference loading.
V5 loading was done previously.

TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/1558093002 .

(cherry picked from commit aab8f462ea3368ed4825172231131e1a10db978d)

Review URL: https://codereview.chromium.org/1556423002 .

1 files changed, 8 insertions, 0 deletions

diff --git a/fpdfsdk/src/fpdfview_embeddertest.cpp b/fpdfsdk/src/fpdfview_embeddertest.cpp
index 3be96e7aef..0f4666836f 100644
--- a/fpdfsdk/src/fpdfview_embeddertest.cpp
+++ b/fpdfsdk/src/fpdfview_embeddertest.cpp
@@ -204,3 +204,11 @@ TEST_F(FPDFViewEmbeddertest, Crasher_454695) {
 TEST_F(FPDFViewEmbeddertest, Hang_298) {
   EXPECT_FALSE(OpenDocument("bug_298.pdf"));
 }
+
+// Test if the document opens without infinite looping.
+// Previously this test will hang in a loop inside LoadAllCrossRefV4. After
+// the fix, LoadAllCrossRefV4 will return false after detecting a cross
+// reference loop. Cross references will be rebuilt successfully.
+TEST_F(FPDFViewEmbeddertest, CrossRefV4Loop) {
+  EXPECT_TRUE(OpenDocument("bug_xrefv4_loop.pdf"));
+}