#Centipede MacOS support 5/X: fix shared_memory_blob_sequence.

PiperOrigin-RevId: 680725159

.github/workflows/bazel_test_centipede.yml

@@ -108,19 +108,25 @@ jobs:
         if: ${{ !cancelled() }}
         run: |
           bazel test --local_test_jobs=1 --test_output=errors --no//fuzztest:use_riegeli \
-            centipede:binary_info_test centipede:call_graph_test \
-            centipede:callstack_test centipede:concurrent_bitset_test \
+            centipede:binary_info_test centipede:byte_array_mutator_test \
+            centipede:call_graph_test centipede:callstack_test \
+            centipede:centipede_binary_test centipede:concurrent_bitset_test \
             centipede:command_test \
             centipede:concurrent_byteset_test centipede:config_file_test \
-            centipede:config_util_test centipede:environment_test \
+            centipede:config_util_test centipede:corpus_io_test \
+            centipede:corpus_test centipede:distill_test \
+            centipede:environment_test centipede:execution_metadata_test \
             centipede:feature_set_test centipede:feature_test \
             centipede:foreach_nonzero_test \
             centipede:hashed_ring_buffer_test centipede:int_utils_test \
-            centipede:knobs_test centipede:pc_info_test \
-            centipede:resource_pool_test \
+            centipede:knobs_test centipede:mutation_input_test \
+            centipede:pc_info_test centipede:resource_pool_test \
             centipede:reverse_pc_table_test centipede:rolling_hash_test \
             centipede:runner_cmp_trace_test centipede:runner_flags_test \
-            centipede:rusage_stats_test \
+            centipede:runner_result_test centipede:rusage_stats_test \
+            centipede:seed_corpus_maker_lib_test \
+            centipede:seed_corpus_maker_proto_lib_test \
+            centipede:shared_memory_blob_sequence_test \
             centipede:stats_test centipede:symbol_table_test \
             centipede:util_test centipede:workdir_test && \
           bazel test --local_test_jobs=1 --test_output=errors --no//fuzztest:use_riegeli --test_filter='-*ValidateTimelapseSnapshots' -- centipede:rusage_profiler_test

centipede/BUILD

@@ -425,7 +425,12 @@ cc_library(
     name = "shared_memory_blob_sequence",
     srcs = ["shared_memory_blob_sequence.cc"],
     hdrs = ["shared_memory_blob_sequence.h"],
-    linkopts = ["-lrt"],  # for shm_open.
+    linkopts = select({
+        "@platforms//os:macos": [],
+        "//conditions:default": [
+            "-lrt",  # for shm_open
+        ],
+    }),
     visibility = PUBLIC_API_VISIBILITY,
     deps = ["@com_google_absl//absl/base:nullability"],
     # don't add any dependencies.

centipede/environment.h

@@ -98,7 +98,11 @@ struct Environment {
   std::string minimize_crash_file_path;
   bool batch_triage_suspect_only = false;
   size_t shmem_size_mb = 1024;
+#ifdef __APPLE__
+  bool use_posix_shmem = true;
+#else
   bool use_posix_shmem = false;
+#endif
   bool dry_run = false;
   bool save_binary_info = false;
   bool populate_binary_info = true;

centipede/execution_metadata_test.cc

@@ -14,6 +14,7 @@
 
 #include "./centipede/execution_metadata.h"
 
+#include <cstdint>
 #include <utility>
 #include <vector>
 
@@ -96,8 +97,9 @@ TEST(ExecutionMetadata, AppendCmpEntryReturnsFalseAndSkipsOnBadArgs) {
 TEST(ExecutionMetadata, ReadAndWriteKeepsCmpEntries) {
   ExecutionMetadata metadata_in;
   ASSERT_TRUE(metadata_in.AppendCmpEntry({1, 2}, {3, 4}));
-  SharedMemoryBlobSequence blobseq("test", /*size=*/1024,
-                                   /*use_posix_shmem=*/false);
+  std::vector<uint8_t> blob_storage;
+  blob_storage.resize(1024);
+  BlobSequence blobseq(blob_storage.data(), blob_storage.size());
   EXPECT_TRUE(metadata_in.Write(/*tag=*/1, blobseq));
   blobseq.Reset();
   Blob blob = blobseq.Read();

centipede/shared_memory_blob_sequence.cc

@@ -108,6 +108,9 @@ SharedMemoryBlobSequence::SharedMemoryBlobSequence(const char *name,
                    "shm_open() path length exceeds PATH_MAX.");
     path_is_owned_ = true;
   } else {
+#ifdef __APPLE__
+    ErrorOnFailure(true, "must use POSIX shmem");
+#else   // __APPLE__
     fd_ = memfd_create(name, MFD_CLOEXEC);
     ErrorOnFailure(fd_ < 0, "memfd_create() failed");
     const size_t path_size =
@@ -116,8 +119,9 @@ SharedMemoryBlobSequence::SharedMemoryBlobSequence(const char *name,
                    "internal fd path length exceeds PATH_MAX.");
     // memfd_create descriptors are automatically freed on close().
     path_is_owned_ = false;
+#endif  // __APPLE__
   }
-  ErrorOnFailure(ftruncate(fd_, static_cast<__off_t>(size_)),
+  ErrorOnFailure(ftruncate(fd_, static_cast<off_t>(size_)),
                  "ftruncate() failed)");
   MmapData();
 }
@@ -154,10 +158,16 @@ SharedMemoryBlobSequence::~SharedMemoryBlobSequence() {
 }
 
 void SharedMemoryBlobSequence::ReleaseSharedMemory() {
+#ifdef __APPLE__
+  // MacOS only allows ftruncate shm once
+  // (https://stackoverflow.com/questions/25502229/ftruncate-not-working-on-posix-shared-memory-in-mac-os-x).
+  // So nothing we can do here.
+#else   // __APPLE__
   // Setting size to 0 releases the memory to OS.
   ErrorOnFailure(ftruncate(fd_, 0) != 0, "ftruncate(0) failed)");
   // Set the size back to `size`. The memory is not actually reserved.
   ErrorOnFailure(ftruncate(fd_, size_) != 0, "ftruncate(size_) failed)");
+#endif  // __APPLE__
 }
 
 size_t SharedMemoryBlobSequence::NumBytesUsed() const {

centipede/shared_memory_blob_sequence_test.cc

@@ -28,8 +28,7 @@ namespace centipede {
 
 std::string ShmemName() {
   std::ostringstream oss;
-  oss << "/shared_memory_blob_sequence_test-" << getpid() << "-"
-      << std::this_thread::get_id();
+  oss << "/shm_test-" << getpid() << "-" << std::this_thread::get_id();
   return oss.str();
 }
 
@@ -54,7 +53,17 @@ TEST(BlobSequence, WriteAndReadAnEmptyBlob) {
 }
 
 class SharedMemoryBlobSequenceTest
-    : public testing::TestWithParam</* use_shm */ bool> {};
+    : public testing::TestWithParam</* use_shm */ bool> {
+ public:
+  void SetUp() override {
+#ifdef __APPLE__
+    const bool use_shm = GetParam();
+    if (!use_shm) {
+      GTEST_SKIP() << "Skipping test that does not use POSIX shmem on MacOS";
+    }
+#endif  // __APPLE__
+  }
+};
 
 INSTANTIATE_TEST_SUITE_P(SharedMemoryBlobSequenceParametrizedTest,
                          SharedMemoryBlobSequenceTest,
@@ -195,6 +204,8 @@ TEST_P(SharedMemoryBlobSequenceTest, WriteAfterReset) {
   EXPECT_FALSE(blob2.IsValid());
 }
 
+// MacOS does not support releasing the shm memory.
+#ifndef __APPLE__
 // Test ReleaseSharedMemory and NumBytesUsed.
 TEST_P(SharedMemoryBlobSequenceTest, ReleaseSharedMemory) {
   // Allocate a blob sequence with 1M bytes of storage.
@@ -207,5 +218,6 @@ TEST_P(SharedMemoryBlobSequenceTest, ReleaseSharedMemory) {
   EXPECT_TRUE(blobseq.Write(Blob({1, 2, 3, 4})));
   EXPECT_GT(blobseq.NumBytesUsed(), 5);
 }
+#endif
 
 }  // namespace centipede