Allow gzip with padding data in LocateDeflatesInGzip. am: 6d30f049ed am: 877c17b5f2

am: e028b001e3

Change-Id: Ia846df7c6ddb78d47f6823812f6b225c57b879fd

2 files changed, 22 insertions, 6 deletions

diff --git a/src/utils.cc b/src/utils.cc
index 668ec3f..de3cc6c 100644
--- a/src/utils.cc
+++ b/src/utils.cc
@@ -181,7 +181,8 @@ bool LocateDeflatesInZlibBlocks(const string& file_path,
 // https://www.ietf.org/rfc/rfc1952.txt
 bool LocateDeflatesInGzip(const Buffer& data, vector<BitExtent>* deflates) {
   uint64_t member_start = 0;
-  while (member_start < data.size()) {
+  while (member_start + 10 <= data.size() && data[member_start + 0] == 0x1F &&
+         data[member_start + 1] == 0x8B && data[member_start + 2] == 8) {
     // Each member entry has the following format
     // 0      1     0x1F
     // 1      1     0x8B
@@ -190,10 +191,6 @@ bool LocateDeflatesInGzip(const Buffer& data, vector<BitExtent>* deflates) {
     // 4      4     modification time
     // 8      1     extra flags
     // 9      1     operating system
-    TEST_AND_RETURN_FALSE(member_start + 10 <= data.size());
-    TEST_AND_RETURN_FALSE(data[member_start + 0] == 0x1F);
-    TEST_AND_RETURN_FALSE(data[member_start + 1] == 0x8B);
-    TEST_AND_RETURN_FALSE(data[member_start + 2] == 8);
 
     uint64_t offset = member_start + 10;
     int flag = data[member_start + 3];
@@ -239,7 +236,8 @@ bool LocateDeflatesInGzip(const Buffer& data, vector<BitExtent>* deflates) {
     offset += 8;
     member_start = offset;
   }
-  return true;
+  // Return true if we've successfully parsed at least one gzip.
+  return member_start != 0;
 }
 
 // For more information about the zip format, refer to
diff --git a/src/utils_unittest.cc b/src/utils_unittest.cc
index 737b765..43f18d0 100644
--- a/src/utils_unittest.cc
+++ b/src/utils_unittest.cc
@@ -195,6 +195,24 @@ TEST(UtilsTest, LocateDeflatesInGzip) {
   EXPECT_EQ(deflates, expected_deflates);
 }
 
+TEST(UtilsTest, LocateDeflatesInGzipFail) {
+  Buffer gzip_data(kGzipEntryWithMultipleMembers,
+                   std::end(kGzipEntryWithMultipleMembers));
+  gzip_data[0] ^= 1;
+  vector<BitExtent> deflates;
+  EXPECT_FALSE(LocateDeflatesInGzip(gzip_data, &deflates));
+}
+
+TEST(UtilsTest, LocateDeflatesInGzipWithPadding) {
+  Buffer gzip_data(kGzipEntryWithMultipleMembers,
+                   std::end(kGzipEntryWithMultipleMembers));
+  gzip_data.resize(gzip_data.size() + 100);
+  vector<BitExtent> deflates;
+  vector<BitExtent> expected_deflates = {{160, 98}, {488, 98}};
+  EXPECT_TRUE(LocateDeflatesInGzip(gzip_data, &deflates));
+  EXPECT_EQ(deflates, expected_deflates);
+}
+
 TEST(UtilsTest, LocateDeflatesInGzipWithExtraField) {
   Buffer gzip_data(kGzipEntryWithExtraField,
                    std::end(kGzipEntryWithExtraField));