1 files changed, 91 insertions, 0 deletions
diff --git a/lib/ubsan_minimal/ubsan_minimal_handlers.cc b/lib/ubsan_minimal/ubsan_minimal_handlers.cc
new file mode 100644
index 000000000..3ab2811c6
--- /dev/null
+++ b/lib/ubsan_minimal/ubsan_minimal_handlers.cc
@@ -0,0 +1,91 @@
+#include <atomic>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static void message(const char *msg) {
+  write(2, msg, strlen(msg));
+}
+
+static const int kMaxCallerPcs = 20;
+static std::atomic<void *> caller_pcs[kMaxCallerPcs];
+// Number of elements in caller_pcs. A special value of kMaxCallerPcs + 1 means
+// that "too many errors" has already been reported.
+static std::atomic<int> caller_pcs_sz;
+
+__attribute__((noinline))
+static bool report_this_error(void *caller) {
+  if (caller == nullptr) return false;
+  while (true) {
+    int sz = caller_pcs_sz.load(std::memory_order_relaxed);
+    if (sz > kMaxCallerPcs) return false; // early exit
+    // when sz==kMaxCallerPcs print "too many errors", but only when cmpxchg
+    // succeeds in order to not print it multiple times.
+    if (sz > 0 && sz < kMaxCallerPcs) {
+      void *p;
+      for (int i = 0; i < sz; ++i) {
+        p = caller_pcs[i].load(std::memory_order_relaxed);
+        if (p == nullptr) break; // Concurrent update.
+        if (p == caller) return false;
+      }
+      if (p == nullptr) continue; // FIXME: yield?
+    }
+
+    if (!caller_pcs_sz.compare_exchange_strong(sz, sz + 1))
+      continue; // Concurrent update! Try again from the start.
+
+    if (sz == kMaxCallerPcs) {
+      message("ubsan: too many errors\n");
+      return false;
+    }
+    caller_pcs[sz].store(caller, std::memory_order_relaxed);
+    return true;
+  }
+}
+
+#if defined(__ANDROID__)
+extern "C" void android_set_abort_message(const char *msg);
+static void abort_with_message(const char *msg) {
+#if __ANDROID_API__ >= 21
+  android_set_abort_message(msg);
+#endif
+  abort();
+}
+#else
+static void abort_with_message(const char *) { abort(); }
+#endif
+
+#define INTERFACE extern "C" __attribute__((visibility("default")))
+
+// FIXME: add caller pc to the error message (possibly as "ubsan: error-type
+// @1234ABCD").
+#define HANDLER(name, msg)                                       \
+  INTERFACE void __ubsan_handle_##name##_minimal() {             \
+    if (!report_this_error(__builtin_return_address(0))) return; \
+    message("ubsan: " msg "\n");                                 \
+  }                                                              \
+                                                                 \
+  INTERFACE void __ubsan_handle_##name##_minimal_abort() {       \
+    message("ubsan: " msg "\n");                                 \
+    abort_with_message("ubsan: " msg);                           \
+  }
+
+HANDLER(type_mismatch, "type-mismatch")
+HANDLER(add_overflow, "add-overflow")
+HANDLER(sub_overflow, "sub-overflow")
+HANDLER(mul_overflow, "mul-overflow")
+HANDLER(negate_overflow, "negate-overflow")
+HANDLER(divrem_overflow, "divrem-overflow")
+HANDLER(shift_out_of_bounds, "shift-out-of-bounds")
+HANDLER(out_of_bounds, "out-of-bounds")
+HANDLER(builtin_unreachable, "builtin-unreachable")
+HANDLER(missing_return, "missing-return")
+HANDLER(vla_bound_not_positive, "vla-bound-not-positive")
+HANDLER(float_cast_overflow, "float-cast-overflow")
+HANDLER(load_invalid_value, "load-invalid-value")
+HANDLER(invalid_builtin, "invalid-builtin")
+HANDLER(function_type_mismatch, "function-type-mismatch")
+HANDLER(nonnull_arg, "nonnull-arg")
+HANDLER(nullability_arg, "nullability-arg")
+HANDLER(pointer_overflow, "pointer-overflow")
+HANDLER(cfi_check_fail, "cfi-check-fail")