Author: labath Date: Tue Jul 26 03:11:57 2016 New Revision: 276734 URL: http://llvm.org/viewvc/llvm-project?rev=276734&view=rev Log: Fix DataExtractor::PeekData for zero length peeks
Summary: The function was returning the null pointer for peeks of size zero, which seems like a sensible thing to do, but is actually pretty easy to get bitten by that if you are extracting a variable length field which happens to be of zero length and then doing pointer arithmetic on that (which SymbolFileDWARF does, and ended up crashing in case of empty DW_AT_location). This changes the function to return a null pointer only when it gets queried for data which is outside of the range of the extractor, which is more c++-y, as one can still do reasonable things with pointers to data of size zero (think, end() iterators). I also add a test and fix some signedness warnings in the existing data extractor tests. Reviewers: clayborg Subscribers: lldb-commits Differential Revision: https://reviews.llvm.org/D22755 Modified: lldb/trunk/include/lldb/Core/DataExtractor.h lldb/trunk/unittests/Core/DataExtractorTest.cpp Modified: lldb/trunk/include/lldb/Core/DataExtractor.h URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Core/DataExtractor.h?rev=276734&r1=276733&r2=276734&view=diff ============================================================================== --- lldb/trunk/include/lldb/Core/DataExtractor.h (original) +++ lldb/trunk/include/lldb/Core/DataExtractor.h Tue Jul 26 03:11:57 2016 @@ -1139,7 +1139,7 @@ public: const uint8_t* PeekData (lldb::offset_t offset, lldb::offset_t length) const { - if (length > 0 && ValidOffsetForDataOfSize(offset, length)) + if (ValidOffsetForDataOfSize(offset, length)) return m_start + offset; return nullptr; } Modified: lldb/trunk/unittests/Core/DataExtractorTest.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/unittests/Core/DataExtractorTest.cpp?rev=276734&r1=276733&r2=276734&view=diff ============================================================================== --- lldb/trunk/unittests/Core/DataExtractorTest.cpp (original) +++ lldb/trunk/unittests/Core/DataExtractorTest.cpp Tue Jul 26 03:11:57 2016 @@ -21,7 +21,7 @@ using namespace lldb_private; TEST(DataExtractorTest, GetBitfield) { - char buffer[] = { 0x01, 0x23, 0x45, 0x67 }; + uint8_t buffer[] = { 0x01, 0x23, 0x45, 0x67 }; DataExtractor LE(buffer, sizeof(buffer), lldb::eByteOrderLittle, sizeof(void *)); DataExtractor BE(buffer, sizeof(buffer), lldb::eByteOrderBig, sizeof(void *)); @@ -33,7 +33,24 @@ TEST(DataExtractorTest, GetBitfield) ASSERT_EQ(buffer[1], BE.GetMaxU64Bitfield(&offset, sizeof(buffer), 8, 8)); offset = 0; - ASSERT_EQ(buffer[1], LE.GetMaxS64Bitfield(&offset, sizeof(buffer), 8, 8)); + ASSERT_EQ(int8_t(buffer[1]), LE.GetMaxS64Bitfield(&offset, sizeof(buffer), 8, 8)); offset = 0; - ASSERT_EQ(buffer[1], BE.GetMaxS64Bitfield(&offset, sizeof(buffer), 8, 8)); + ASSERT_EQ(int8_t(buffer[1]), BE.GetMaxS64Bitfield(&offset, sizeof(buffer), 8, 8)); +} + +TEST(DataExtractorTest, PeekData) +{ + uint8_t buffer[] = { 0x01, 0x02, 0x03, 0x04 }; + DataExtractor E(buffer, sizeof buffer, lldb::eByteOrderLittle, 4); + + EXPECT_EQ(buffer + 0, E.PeekData(0, 0)); + EXPECT_EQ(buffer + 0, E.PeekData(0, 4)); + EXPECT_EQ(nullptr, E.PeekData(0, 5)); + + EXPECT_EQ(buffer + 2, E.PeekData(2, 0)); + EXPECT_EQ(buffer + 2, E.PeekData(2, 2)); + EXPECT_EQ(nullptr, E.PeekData(2, 3)); + + EXPECT_EQ(buffer + 4, E.PeekData(4, 0)); + EXPECT_EQ(nullptr, E.PeekData(4, 1)); } _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
