Implement symbol resolution for non-funct ptr std::function objects

tracetools/include/tracetools/utils.hpp

@@ -18,18 +18,40 @@
 #include <stddef.h>
 #include <functional>
 
+#define SYMBOL_UNKNOWN "UNKNOWN"
+
+const char * _demangle_symbol(const char * mangled);
+
+const char * _get_symbol_funcptr(void * funcptr);
+
 template<typename T, typename ... U>
-void * get_address(std::function<T(U...)> f)
+const char * _get_symbol_non_funcptr(std::function<T(U...)> f)
 {
-  typedef T (fnType)(U...);
-  fnType ** fnPointer = f.template target<fnType *>();
-  // Might be a lambda
-  if (fnPointer == nullptr) {
-    return 0;
-  }
-  return reinterpret_cast<void *>(*fnPointer);
+#if defined(TRACETOOLS_LTTNG_ENABLED) && !defined(_WIN32)
+  return _demangle_symbol(f.target_type().name());
+#else
+  (void)f;
+  return SYMBOL_UNKNOWN;
+#endif
 }
 
-const char * get_symbol(void * funptr);
+template<typename T, typename ... U>
+const char * get_symbol(std::function<T(U...)> f)
+{
+#if defined(TRACETOOLS_LTTNG_ENABLED) && !defined(_WIN32)
+  typedef T (fnType)(U...);
+  fnType ** fnPointer = f.template target<fnType *>();
+  // If we get an actual address
+  if (fnPointer != nullptr) {
+    void * funcptr = reinterpret_cast<void *>(*fnPointer);
+    return _get_symbol_funcptr(funcptr);
+  }
+  // Otherwise we have to go through target_type()
+  return _get_symbol_non_funcptr(f);
+#else
+  (void)f;
+  return SYMBOL_UNKNOWN;
+#endif
+}
 
 #endif  // TRACETOOLS__UTILS_HPP_

tracetools/src/utils.cpp

@@ -12,38 +12,37 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <iostream>
-
 #if defined(TRACETOOLS_LTTNG_ENABLED) && !defined(_WIN32)
 #include <dlfcn.h>
 #include <cxxabi.h>
 #endif
 #include "tracetools/utils.hpp"
 
-const char * get_symbol(void * funptr)
+const char * _demangle_symbol(const char * mangled)
 {
-#define SYMBOL_UNKNOWN "UNKNOWN"
 #if defined(TRACETOOLS_LTTNG_ENABLED) && !defined(_WIN32)
-#define SYMBOL_LAMBDA "[lambda]"
-  if (funptr == 0) {
-    std::cout << "lamba!" << std::endl;
-    return SYMBOL_LAMBDA;
-  }
-
-  Dl_info info;
-  if (dladdr(funptr, &info) == 0) {
-    std::cout << "unknown!" << std::endl;
-    return SYMBOL_UNKNOWN;
-  }
-
   char * demangled = nullptr;
   int status;
-  demangled = abi::__cxa_demangle(info.dli_sname, NULL, 0, &status);
+  demangled = abi::__cxa_demangle(mangled, NULL, 0, &status);
   // Use demangled symbol if possible
-  const char * demangled_val = (status == 0 ? demangled : info.dli_sname);
+  const char * demangled_val = (status == 0 ? demangled : mangled);
   return demangled_val != 0 ? demangled_val : SYMBOL_UNKNOWN;
 #else
-  (void)funptr;
+  (void)mangled;
+  return SYMBOL_UNKNOWN;
+#endif
+}
+
+const char * _get_symbol_funcptr(void * funcptr)
+{
+#if defined(TRACETOOLS_LTTNG_ENABLED) && !defined(_WIN32)
+  Dl_info info;
+  if (dladdr(funcptr, &info) == 0) {
+    return SYMBOL_UNKNOWN;
+  }
+  return _demangle_symbol(info.dli_sname);
+#else
+  (void)funcptr;
   return SYMBOL_UNKNOWN;
 #endif
 }

tracetools/test/test_utils.cpp

@@ -44,14 +44,11 @@ TEST(TestUtils, valid_address_symbol) {
   // Function pointer
   std::function<void(std::shared_ptr<int>)> f = &function_shared;
   // Address for one with an actual underlying function should be non-zero
-  ASSERT_GT(get_address(f), (void *)0) << "get_address() for function not valid";
-  ASSERT_STREQ(get_symbol(get_address(f)), "function_shared(std::shared_ptr<int>)") <<
+  ASSERT_STREQ(get_symbol(f), "function_shared(std::shared_ptr<int>)") <<
     "invalid function name";
 
   // Lambda
   std::function<int(int)> l = [](int num) {return num + 1;};
-  // Address for an std::function with an underlying lambda should be nullptr
-  ASSERT_EQ(get_address(l), nullptr) << "get_address() for lambda std::function not 0";
   // TODO(christophebedard) check symbol
 
   // Bind (to member function)
@@ -62,6 +59,5 @@ TEST(TestUtils, valid_address_symbol) {
     std::placeholders::_1,
     std::placeholders::_2
   );
-  ASSERT_EQ(get_address(fscwc), nullptr) << "get_address() for std::bind std::function not 0";
   // TODO(christophebedard) check symbol
 }