Remove the legacy stateless symbol decorator API.

PiperOrigin-RevId: 884958234
Change-Id: I288a4b143718a155663669b7d2e4a24a89d754ec

Author: Abseil Team

absl/debugging/internal/symbolize.h

@@ -78,46 +78,6 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
-// Legacy stateless symbol decorator API. Will be removed soon.
-struct SymbolDecoratorArgs {
-  // The program counter we are getting symbolic name for.
-  const void *pc;
-  // 0 for main executable, load address for shared libraries.
-  ptrdiff_t relocation;
-  // Read-only file descriptor for ELF image covering "pc",
-  // or -1 if no such ELF image exists in /proc/self/maps.
-  int fd;
-  // Output buffer, size.
-  // Note: the buffer may not be empty -- default symbolizer may have already
-  // produced some output, and earlier decorators may have adorned it in
-  // some way. You are free to replace or augment the contents (within the
-  // symbol_buf_size limit).
-  char *const symbol_buf;
-  size_t symbol_buf_size;
-  // Temporary scratch space, size.
-  // Use that space in preference to allocating your own stack buffer to
-  // conserve stack.
-  char *const tmp_buf;
-  size_t tmp_buf_size;
-  // User-provided argument
-  void* arg;
-};
-using LegacySymbolDecorator = void (*)(const SymbolDecoratorArgs *);
-
-// Installs a function-pointer as a decorator. Returns a value less than zero
-// if the system cannot install the decorator. Otherwise, returns a unique
-// identifier corresponding to the decorator. This identifier can be used to
-// uninstall the decorator - See RemoveSymbolDecorator() below.
-int InstallSymbolDecorator(LegacySymbolDecorator decorator, void* arg);
-
-// Removes a previously installed function-pointer decorator. Parameter "ticket"
-// is the return-value from calling InstallSymbolDecorator().
-bool RemoveSymbolDecorator(int ticket);
-
-// Remove all installed decorators.  Returns true if successful, false if
-// symbolization is currently in progress.
-bool RemoveAllSymbolDecorators();
-
 class SymbolDecorator;
 
 class SymbolDecoratorDeleter {

absl/debugging/symbolize_elf.inc

@@ -146,17 +146,6 @@ inline constexpr bool kPlatformUsesOPDSections = false;
 // pointers and the first one is the function's entry.
 const size_t kFunctionDescriptorSize = sizeof(void *) * 2;
 
-const int kMaxDecorators = 10;  // Seems like a reasonable upper limit.
-
-struct InstalledSymbolDecorator {
-  LegacySymbolDecorator fn;
-  void *arg;
-  int ticket;
-};
-
-int g_num_decorators;
-InstalledSymbolDecorator g_decorators[kMaxDecorators];
-
 std::atomic<SymbolDecorator::Factory*> g_decorator_factory = nullptr;
 
 struct FileMappingHint {
@@ -166,16 +155,6 @@ struct FileMappingHint {
   const char *filename;
 };
 
-// Protects g_decorators.
-// We are using SpinLock and not a Mutex here, because we may be called
-// from inside Mutex::Lock itself, and it prohibits recursive calls.
-// This happens in e.g. base/stacktrace_syscall_unittest.
-// Moreover, we are using only try_lock(), if the decorator list
-// is being modified (is busy), we skip all decorators, and possibly
-// loose some info. Sorry, that's the best we could do.
-ABSL_CONST_INIT absl::base_internal::SpinLock g_decorators_mu(
-    absl::base_internal::SCHEDULE_KERNEL_ONLY);
-
 const int kMaxFileMappingHints = 8;
 int g_num_file_mapping_hints;
 FileMappingHint g_file_mapping_hints[kMaxFileMappingHints];
@@ -1507,7 +1486,6 @@ static bool MaybeInitializeObjFile(
 const char *Symbolizer::GetUncachedSymbol(const void *pc) {
   ObjFile *const obj = FindObjFile(pc, 1);
   ptrdiff_t relocation = 0;
-  int fd = -1;
   if (obj != nullptr) {
     if (MaybeInitializeObjFile(obj, decorator_factory_)) {
       const size_t start_addr = reinterpret_cast<size_t>(obj->start_addr);
@@ -1549,7 +1527,6 @@ const char *Symbolizer::GetUncachedSymbol(const void *pc) {
         }
       }
 
-      fd = obj->fd;
       if (GetSymbolFromObjectFile(*obj, pc, relocation, symbol_buf_,
                                   sizeof(symbol_buf_), tmp_buf_,
                                   sizeof(tmp_buf_)) == SYMBOL_FOUND) {
@@ -1574,18 +1551,6 @@ const char *Symbolizer::GetUncachedSymbol(const void *pc) {
 #endif
   }
 
-  if (g_decorators_mu.try_lock()) {
-    if (g_num_decorators > 0) {
-      SymbolDecoratorArgs decorator_args = {
-          pc,       relocation,       fd,     symbol_buf_, sizeof(symbol_buf_),
-          tmp_buf_, sizeof(tmp_buf_), nullptr};
-      for (int i = 0; i < g_num_decorators; ++i) {
-        decorator_args.arg = g_decorators[i].arg;
-        g_decorators[i].fn(&decorator_args);
-      }
-    }
-    g_decorators_mu.unlock();
-  }
   if (obj != nullptr && obj->decorator != nullptr) {
     obj->decorator->Decorate(pc, relocation, symbol_buf_, sizeof(symbol_buf_),
                              tmp_buf_, sizeof(tmp_buf_));
@@ -1633,55 +1598,6 @@ const char *Symbolizer::GetSymbol(const void *pc) {
 #endif
 }
 
-bool RemoveAllSymbolDecorators() {
-  SetSymbolDecoratorFactory(nullptr);
-
-  if (!g_decorators_mu.try_lock()) {
-    // Someone else is using decorators. Get out.
-    return false;
-  }
-  g_num_decorators = 0;
-  g_decorators_mu.unlock();
-  return true;
-}
-
-bool RemoveSymbolDecorator(int ticket) {
-  if (!g_decorators_mu.try_lock()) {
-    // Someone else is using decorators. Get out.
-    return false;
-  }
-  for (int i = 0; i < g_num_decorators; ++i) {
-    if (g_decorators[i].ticket == ticket) {
-      while (i < g_num_decorators - 1) {
-        g_decorators[i] = g_decorators[i + 1];
-        ++i;
-      }
-      g_num_decorators = i;
-      break;
-    }
-  }
-  g_decorators_mu.unlock();
-  return true;  // Decorator is known to be removed.
-}
-
-int InstallSymbolDecorator(LegacySymbolDecorator decorator, void *arg) {
-  static int ticket = 0;
-
-  if (!g_decorators_mu.try_lock()) {
-    // Someone else is using decorators. Get out.
-    return -2;
-  }
-  int ret = ticket;
-  if (g_num_decorators >= kMaxDecorators) {
-    ret = -1;
-  } else {
-    g_decorators[g_num_decorators] = {decorator, arg, ticket++};
-    ++g_num_decorators;
-  }
-  g_decorators_mu.unlock();
-  return ret;
-}
-
 SymbolDecorator::Factory* SetSymbolDecoratorFactory(
     SymbolDecorator::Factory* factory) {
   return g_decorator_factory.exchange(factory, std::memory_order_acq_rel);

absl/debugging/symbolize_test.cc

@@ -375,48 +375,6 @@ TEST(Symbolize, SymbolizeWithMultipleMaps) {
   }
 }
 
-// Appends string(*args->arg) to args->symbol_buf.
-static void DummySymbolDecorator(
-    const absl::debugging_internal::SymbolDecoratorArgs *args) {
-  std::string *message = static_cast<std::string *>(args->arg);
-  strncat(args->symbol_buf, message->c_str(),
-          args->symbol_buf_size - strlen(args->symbol_buf) - 1);
-}
-
-TEST(Symbolize, InstallAndRemoveSymbolDecorators) {
-  int ticket_a;
-  std::string a_message("a");
-  EXPECT_GE(ticket_a = absl::debugging_internal::InstallSymbolDecorator(
-                DummySymbolDecorator, &a_message),
-            0);
-
-  int ticket_b;
-  std::string b_message("b");
-  EXPECT_GE(ticket_b = absl::debugging_internal::InstallSymbolDecorator(
-                DummySymbolDecorator, &b_message),
-            0);
-
-  int ticket_c;
-  std::string c_message("c");
-  EXPECT_GE(ticket_c = absl::debugging_internal::InstallSymbolDecorator(
-                DummySymbolDecorator, &c_message),
-            0);
-
-  // Use addresses 4 and 8 here to ensure that we always use valid addresses
-  // even on systems that require instructions to be 32-bit aligned.
-  char *address = reinterpret_cast<char *>(4);
-  EXPECT_STREQ("abc", TrySymbolize(address));
-
-  EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_b));
-
-  EXPECT_STREQ("ac", TrySymbolize(address + 4));
-
-  // Cleanup: remove all remaining decorators so other stack traces don't
-  // get mystery "ac" decoration.
-  EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_a));
-  EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_c));
-}
-
 template <char C>
 class TestSymbolDecorator final
     : public absl::debugging_internal::SymbolDecorator {

absl/debugging/symbolize_unimplemented.inc

@@ -21,10 +21,6 @@ ABSL_NAMESPACE_BEGIN
 
 namespace debugging_internal {
 
-int InstallSymbolDecorator(LegacySymbolDecorator, void*) { return -1; }
-bool RemoveSymbolDecorator(int) { return false; }
-bool RemoveAllSymbolDecorators(void) { return false; }
-
 SymbolDecorator::Factory* SetSymbolDecoratorFactory(SymbolDecorator::Factory*) {
   return nullptr;
 }