Lex: Check for 0 buckets on header map construction
Switch to using `isPowerOf2_32()` to check whether the buckets are a
power of two, and as a side benefit reject loading a header map with no
buckets. This is a follow-up to r261448.
llvm-svn: 261585
diff --git a/clang/lib/Lex/HeaderMap.cpp b/clang/lib/Lex/HeaderMap.cpp
index 67b6631..be0d477 100644
--- a/clang/lib/Lex/HeaderMap.cpp
+++ b/clang/lib/Lex/HeaderMap.cpp
@@ -86,10 +86,10 @@
// Check the number of buckets. It should be a power of two, and there
// should be enough space in the file for all of them.
- auto NumBuckets = NeedsByteSwap
- ? llvm::sys::getSwappedBytes(Header->NumBuckets)
- : Header->NumBuckets;
- if (NumBuckets & (NumBuckets - 1))
+ uint32_t NumBuckets = NeedsByteSwap
+ ? llvm::sys::getSwappedBytes(Header->NumBuckets)
+ : Header->NumBuckets;
+ if (!llvm::isPowerOf2_32(NumBuckets))
return false;
if (File.getBufferSize() <
sizeof(HMapHeader) + sizeof(HMapBucket) * NumBuckets)
@@ -208,7 +208,7 @@
unsigned NumBuckets = getEndianAdjustedWord(Hdr.NumBuckets);
// Don't probe infinitely. This should be checked before constructing.
- assert(!(NumBuckets & (NumBuckets - 1)) && "Expected power of 2");
+ assert(llvm::isPowerOf2_32(NumBuckets) && "Expected power of 2");
// Linearly probe the hash table.
for (unsigned Bucket = HashHMapKey(Filename);; ++Bucket) {
diff --git a/clang/unittests/Lex/HeaderMapTest.cpp b/clang/unittests/Lex/HeaderMapTest.cpp
index e892170..ad0579a 100644
--- a/clang/unittests/Lex/HeaderMapTest.cpp
+++ b/clang/unittests/Lex/HeaderMapTest.cpp
@@ -143,6 +143,15 @@
ASSERT_FALSE(HeaderMapImpl::checkHeader(*File.getBuffer(), NeedsSwap));
}
+TEST(HeaderMapTest, checkHeader0Buckets) {
+ // Create with 1 bucket to avoid 0-sized arrays.
+ MapFile<1, 1> File;
+ File.init();
+ File.Header.NumBuckets = 0;
+ bool NeedsSwap;
+ ASSERT_FALSE(HeaderMapImpl::checkHeader(*File.getBuffer(), NeedsSwap));
+}
+
TEST(HeaderMapTest, checkHeaderNotEnoughBuckets) {
MapFile<1, 1> File;
File.init();