From 4a8b8ff576265eb20d5dda28e7cb4ef8d0da1159 Mon Sep 17 00:00:00 2001 From: "Duncan P. N. Exon Smith" Date: Sat, 20 Feb 2016 21:00:58 +0000 Subject: [PATCH] Lex: Check buckets on header map construction If the number of buckets is not a power of two, immediately recognize the header map as corrupt, rather than waiting for the first lookup. I converted the later check to an assert. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@261448 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Lex/HeaderMap.cpp | 16 ++++++++++++---- unittests/Lex/HeaderMapTest.cpp | 9 +++++++++ 2 files changed, 21 insertions(+), 4 deletions(-) diff --git a/lib/Lex/HeaderMap.cpp b/lib/Lex/HeaderMap.cpp index 26a179cf4e..2b31ab9d04 100644 --- a/lib/Lex/HeaderMap.cpp +++ b/lib/Lex/HeaderMap.cpp @@ -19,6 +19,7 @@ #include "llvm/Support/DataTypes.h" #include "llvm/Support/MathExtras.h" #include "llvm/Support/MemoryBuffer.h" +#include "llvm/Support/SwapByteOrder.h" #include #include using namespace clang; @@ -82,6 +83,15 @@ bool HeaderMapImpl::checkHeader(const llvm::MemoryBuffer &File, if (Header->Reserved != 0) return false; + // Check the number of buckets. + auto NumBuckets = NeedsByteSwap + ? llvm::sys::getSwappedBytes(Header->NumBuckets) + : Header->NumBuckets; + + // If the number of buckets is not a power of two, the headermap is corrupt. + if (NumBuckets & (NumBuckets - 1)) + return false; + // Okay, everything looks good. return true; } @@ -191,10 +201,8 @@ StringRef HeaderMapImpl::lookupFilename(StringRef Filename, const HMapHeader &Hdr = getHeader(); unsigned NumBuckets = getEndianAdjustedWord(Hdr.NumBuckets); - // If the number of buckets is not a power of two, the headermap is corrupt. - // Don't probe infinitely. - if (NumBuckets & (NumBuckets-1)) - return StringRef(); + // Don't probe infinitely. This should be checked before constructing. + assert(!(NumBuckets & (NumBuckets - 1)) && "Expected power of 2"); // Linearly probe the hash table. for (unsigned Bucket = HashHMapKey(Filename);; ++Bucket) { diff --git a/unittests/Lex/HeaderMapTest.cpp b/unittests/Lex/HeaderMapTest.cpp index 726e89c275..b8e1d6c46a 100644 --- a/unittests/Lex/HeaderMapTest.cpp +++ b/unittests/Lex/HeaderMapTest.cpp @@ -91,4 +91,13 @@ TEST(HeaderMapTest, checkHeaderValidButEmpty) { ASSERT_TRUE(NeedsSwap); } +TEST(HeaderMapTest, checkHeader3Buckets) { + MapFile<3, 1> File; + ASSERT_EQ(3 * sizeof(HMapBucket), sizeof(File.Buckets)); + + File.init(); + bool NeedsSwap; + ASSERT_FALSE(HeaderMapImpl::checkHeader(*File.getBuffer(), NeedsSwap)); +} + } // end namespace -- 2.40.0