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Make llvm::crc32() work also for input sizes larger than 32 bits.

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The problem was noticed by the Chrome OS toolchain folks
(crbug.com/1048445) because llvm-objcopy --add-gnu-debuglink would
insert the wrong checksum when processing a binary larger than 4 GB.
That use case regressed in 1e1e3ba2526 when we started using
llvm::crc32() in more places.

Differential revision: https://reviews.llvm.org/D74039
This commit is contained in:
Hans Wennborg 2020-02-05 11:03:49 +01:00
parent debe0a8e3b
commit ab9f34b755
2 changed files with 29 additions and 1 deletions
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10
lib/Support/CRC.cpp
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@ -85,7 +85,15 @@ uint32_t llvm::crc32(uint32_t CRC, ArrayRef<uint8_t> Data) {
#include <zlib.h> #include <zlib.h>
uint32_t llvm::crc32(uint32_t CRC, ArrayRef<uint8_t> Data) { uint32_t llvm::crc32(uint32_t CRC, ArrayRef<uint8_t> Data) {
return ::crc32(CRC, (const Bytef *)Data.data(), Data.size()); // Zlib's crc32() only takes a 32-bit length, so we have to iterate for larger
// sizes. One could use crc32_z() instead, but that's a recent (2017) addition
// and may not be available on all systems.
do {
ArrayRef<uint8_t> Slice = Data.take_front(UINT32_MAX);
CRC = ::crc32(CRC, (const Bytef *)Slice.data(), (uInt)Slice.size());
Data = Data.drop_front(Slice.size());
} while (Data.size() > 0);
return CRC;
} }
#endif #endif

20
unittests/Support/CRCTest.cpp
View File

@ -13,6 +13,7 @@
#include "llvm/Support/CRC.h" #include "llvm/Support/CRC.h"
#include "llvm/ADT/StringExtras.h" #include "llvm/ADT/StringExtras.h"
#include "gtest/gtest.h" #include "gtest/gtest.h"
#include <stdlib.h>
using namespace llvm; using namespace llvm;
@ -39,6 +40,25 @@ TEST(CRCTest, CRC32) {
uint8_t byte = i; uint8_t byte = i;
EXPECT_EQ(crc, ~llvm::crc32(0xFFFFFFFFU, byte)); EXPECT_EQ(crc, ~llvm::crc32(0xFFFFFFFFU, byte));
} }
EXPECT_EQ(0x00000000U, llvm::crc32(arrayRefFromStringRef("")));
} }
#if (SIZE_MAX > UINT32_MAX) && defined(EXPENSIVE_CHECKS)
TEST(CRCTest, LargeCRC32) {
// Check that crc32 can handle inputs with sizes larger than 32 bits.
size_t TestSize = (size_t)UINT32_MAX + 42;
uint8_t *TestData = (uint8_t*)calloc(TestSize, 1);
if (!TestData)
return;
// Test expectation generated with:
// $ truncate --size=`echo 2^32-1+42 | bc` /tmp/foo
// $ crc32 /tmp/foo
EXPECT_EQ(0xE46F28FBU, llvm::crc32(makeArrayRef(TestData, TestSize)));
free(TestData);
}
#endif
} // end anonymous namespace } // end anonymous namespace