[Windows] Use llvm-symbolizer before using dbghelp

[rnk]

Summary

llvm-symbolizer understands both PDBs and DWARF, so it's a better bet if
it's available. It prints out the function parameter types and column
numbers, so I needed to churn the expected test output a bit.

This makes most of the llvm-symbolizer subprocessing code
target-independent. Pipes on all platforms use fd_t, and we can use the
portable ReadFromFile / WriteToFile wrappers in symbolizer_sanitizer.cc.
Only the pipe creation and process spawning is Windows-specific.

Please check that the libcdep layering is still correct. I don't know
how to reproduce the build configuration that relies on that.

[samsonov]

Looks like some auxiliary NFC changes can be reviewed or landed separately to minimize the diff. As for libcdep/nolibc I think that "make check-all" on Linux should properly check for that.

lib/sanitizer_common/sanitizer_common.cc

347 ↗

(On Diff #31418)

Move this function in a separate change.

355 ↗

(On Diff #31418)

Use a named constant for pathsep

lib/sanitizer_common/sanitizer_symbolizer_win.cc

196

Shouldn't you actually check for backslash?

271

Does Windows properly handle common_flags()->symbolize? We shouldn't create any symbolizers if this flag is true.

test/asan/CMakeLists.txt

19

Let's introduce COMPILER_RT_HAS_LLD_SOURCES in the same way we use COMPILER_RT_HAS_LIBCXX_SOURCES, and use a common variable to check if lld is available somewhere in test/lit.common.configured.in instead of ASAN_HAS_LLD

20

Copy-paste error

test/asan/TestCases/Windows/operator_new_left_oob.cc

14 ↗

(On Diff #31418)

Please relax all these test cases in a separate change.

[rnk]

lib/sanitizer_common/sanitizer_common.cc

347 ↗

(On Diff #31418)

D11920

lib/sanitizer_common/sanitizer_symbolizer_win.cc

271

Apparently not. I added that here.

test/asan/CMakeLists.txt

19

OK

test/asan/TestCases/Windows/operator_new_left_oob.cc

14 ↗

(On Diff #31418)

rL244522

[rnk]

• Split stuff out and a few updates

[rnk]

• Fix gotsan build by moving symbolization to sanitizer_symbolize_libcdep.cc

[samsonov]

CMakeLists.txt

358 ↗

(On Diff #31745)

Please land this (together with lit config and test/cfi changes) in a separate small commit.

lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc

306

Why do you need to optionally return false (and fallback to the next symbolizer in chain here?

401

Looks like just_read can't be -1 now, when we properly return the error from ReadFromFile function. Just delete this case.

420

Same here: write_len can't be -1 if success is true. In fact, these changes (and CloseFile change above) are bugfixes, because checking for -1 was wrong in the first place - one should have called internal_iserror on the result of internal_write instead. I would appreciate if you will replace internal_read / internal_write / internal_close with ReadFromFile / WriteToFile / CloseFile as a separate small commit preceding this one.

lib/sanitizer_common/sanitizer_symbolizer_process_libcdep.cc

1

This file makes little sense now, after you've moved significant part of SymbolizerProcess implementation to sanitizer_symbolizer_libcdep.cc. Probably, now you can move the only remaining function to sanitizer_symbolizer_posix_libcdep.cc, and delete this file?

[rnk]

CMakeLists.txt

358 ↗

(On Diff #31745)

rL244549

lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc

306

I guess I don't anymore, now that the test case updates have landed. Previously I was trying to make it so that asan would use dbghelp for modules with PDBs and llvm-symbolizer for modules with DWARF. What I discovered was that llvm-symbolizer handles both PDBs and DWARF *and* provides column information, which dbghelp does not. At that point, I made the test case updates and reordered things to prefer llvm-symbolizer over dbghelp.

I probably don't need this functionality anymore, but it seems useful to me. llvm-symbolizer might not be able to answer a particular query, and this lets some other tool try.

420

rL244546

[rnk]

• Rebase

[rnk]

lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc

273–291

This tokenization change here might be worth looking at closely, it's pretty horrible.

[samsonov]

LGTM. Please watch the bots after the commit. Thank you!

lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc

273–291

Yep, I've noticed this horridness. Might worth moving into a separate function btw.

283

Why not ExtractInt(last_colon + 1, "", &info->line)?

306

I see, but I'd rather avoid changing the behavior here. If llvm-symbolizer (on Linux/Mac) failed to get function name, it indeed probably means that there is no debug info, and no way for us to get meaningful information for stack trace - so why try the alternatives? If there *is* some debug info, and llvm-symbolizer weren't able to locate it - we want to actually learn about this and fix a bug.

lib/sanitizer_common/CMakeLists.txt

set(SANITIZER_LIBCDEP_SOURCES
   sanitizer_coverage_libcdep.cc
   sanitizer_coverage_mapping_libcdep.cc
   sanitizer_linux_libcdep.cc
   sanitizer_posix_libcdep.cc
   sanitizer_stacktrace_libcdep.cc
   sanitizer_stoptheworld_linux_libcdep.cc
   sanitizer_symbolizer_libcdep.cc
   sanitizer_symbolizer_posix_libcdep.cc
-  sanitizer_symbolizer_process_libcdep.cc
   sanitizer_unwind_linux_libcdep.cc)
 
 # Explicitly list all sanitizer_common headers. Not all of these are
 # included in sanitizer_common source files, but we need to depend on
 # headers when building our custom unit tests.
 set(SANITIZER_HEADERS
   sanitizer_addrhashmap.h
   sanitizer_allocator.h
set(SANITIZER_HEADERS
   sanitizer_stacktrace.h
   sanitizer_stacktrace_printer.h
   sanitizer_stoptheworld.h
   sanitizer_suppressions.h
   sanitizer_symbolizer.h
   sanitizer_symbolizer_internal.h
   sanitizer_symbolizer_libbacktrace.h
   sanitizer_symbolizer_mac.h
-  sanitizer_symbolizer_win.h
   sanitizer_syscall_generic.inc
   sanitizer_syscall_linux_x86_64.inc
   sanitizer_thread_registry.h)
 
 set(SANITIZER_COMMON_DEFINITIONS)
 
 if(MSVC)
   list(APPEND SANITIZER_COMMON_DEFINITIONS

lib/sanitizer_common/sanitizer_symbolizer_internal.h

 // SymbolizerProcess encapsulates communication between the tool and
 // external symbolizer program, running in a different subprocess.
 // SymbolizerProcess may not be used from two threads simultaneously.
 class SymbolizerProcess {
  public:
   explicit SymbolizerProcess(const char *path, bool use_forkpty = false);
   const char *SendCommand(const char *command);
 
- private:
-  bool Restart();
-  const char *SendCommandImpl(const char *command);
-  bool ReadFromSymbolizer(char *buffer, uptr max_length);
-  bool WriteToSymbolizer(const char *buffer, uptr length);
-  bool StartSymbolizerSubprocess();
-
+ protected:
   virtual bool ReachedEndOfOutput(const char *buffer, uptr length) const {
     UNIMPLEMENTED();
   }
 
-  virtual void ExecuteWithDefaultArgs(const char *path_to_binary) const {
+  /// The maximum number of arguments required to invoke a tool process.
+  enum { kArgVMax = 6 };
+
+  /// Fill in an argv array to invoke the child process.
+  virtual void GetArgV(const char *path_to_binary,
+                       const char *(&argv)[kArgVMax]) const {
     UNIMPLEMENTED();
   }
 
+ private:
+  bool Restart();
+  const char *SendCommandImpl(const char *command);
+  bool ReadFromSymbolizer(char *buffer, uptr max_length);
+  bool WriteToSymbolizer(const char *buffer, uptr length);
+  bool StartSymbolizerSubprocess();
+
   const char *path_;
   fd_t input_fd_;
   fd_t output_fd_;
 
   static const uptr kBufferSize = 16 * 1024;
   char buffer_[kBufferSize];
 
   static const uptr kMaxTimesRestarted = 5;
   static const int kSymbolizerStartupTimeMillis = 10;
   uptr times_restarted_;
   bool failed_to_start_;
   bool reported_invalid_path_;
   bool use_forkpty_;
 };
 
+class LLVMSymbolizerProcess;
+
+// This tool invokes llvm-symbolizer in a subprocess. It should be as portable
+// as the llvm-symbolizer tool is.
+class LLVMSymbolizer : public SymbolizerTool {
+ public:
+  explicit LLVMSymbolizer(const char *path, LowLevelAllocator *allocator);
+
+  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override;
+
+  bool SymbolizeData(uptr addr, DataInfo *info) override;
+
+ private:
+  const char *SendCommand(bool is_data, const char *module_name,
+                          uptr module_offset);
+
+  LLVMSymbolizerProcess *symbolizer_process_;
+  static const uptr kBufferSize = 16 * 1024;
+  char buffer_[kBufferSize];
+};
+
+// Parses one or more two-line strings in the following format:
+//   <function_name>
+//   <file_name>:<line_number>[:<column_number>]
+// Used by LLVMSymbolizer, Addr2LinePool and InternalSymbolizer, since all of
+// them use the same output format.  Returns true if any useful debug
+// information was found.
+bool ParseSymbolizePCOutput(const char *str, SymbolizedStack *res);
+
+// Parses a two-line string in the following format:
+//   <symbol_name>
+//   <start_address> <size>
+// Used by LLVMSymbolizer and InternalSymbolizer.
+void ParseSymbolizeDataOutput(const char *str, DataInfo *info);
+
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_SYMBOLIZER_INTERNAL_H

lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc

Symbolizer *Symbolizer::GetOrInit() {
   SpinMutexLock l(&init_mu_);
   if (symbolizer_)
     return symbolizer_;
   symbolizer_ = PlatformInit();
   CHECK(symbolizer_);
   return symbolizer_;
 }
 
+// For now we assume the following protocol:
+// For each request of the form
+//   <module_name> <module_offset>
+// passed to STDIN, external symbolizer prints to STDOUT response:
+//   <function_name>
+//   <file_name>:<line_number>:<column_number>
+//   <function_name>
+//   <file_name>:<line_number>:<column_number>
+//   ...
+//   <empty line>
+class LLVMSymbolizerProcess : public SymbolizerProcess {
+ public:
+  explicit LLVMSymbolizerProcess(const char *path) : SymbolizerProcess(path) {}
+
+ private:
+  bool ReachedEndOfOutput(const char *buffer, uptr length) const override {
+    // Empty line marks the end of llvm-symbolizer output.
+    return length >= 2 && buffer[length - 1] == '\n' &&
+           buffer[length - 2] == '\n';
+  }
+
+  void GetArgV(const char *path_to_binary,
+               const char *(&argv)[kArgVMax]) const override {
+#if defined(__x86_64h__)
+    const char* const kSymbolizerArch = "--default-arch=x86_64h";
+#elif defined(__x86_64__)
+    const char* const kSymbolizerArch = "--default-arch=x86_64";
+#elif defined(__i386__)
+    const char* const kSymbolizerArch = "--default-arch=i386";
+#elif defined(__powerpc64__) && defined(__BIG_ENDIAN__)
+    const char* const kSymbolizerArch = "--default-arch=powerpc64";
+#elif defined(__powerpc64__) && defined(__LITTLE_ENDIAN__)
+    const char* const kSymbolizerArch = "--default-arch=powerpc64le";
+#else
+    const char* const kSymbolizerArch = "--default-arch=unknown";
+#endif
+
+    const char *const inline_flag = common_flags()->symbolize_inline_frames
+                                        ? "--inlining=true"
+                                        : "--inlining=false";
+    int i = 0;
+    argv[i++] = path_to_binary;
+    argv[i++] = inline_flag;
+    argv[i++] = kSymbolizerArch;
+    argv[i++] = nullptr;
+  }
+};
+
+LLVMSymbolizer::LLVMSymbolizer(const char *path, LowLevelAllocator *allocator)
+    : symbolizer_process_(new(*allocator) LLVMSymbolizerProcess(path)) {}
+
+// Parses one or more two-line strings in the following format:
+//   <function_name>
+//   <file_name>:<line_number>[:<column_number>]
+// Used by LLVMSymbolizer, Addr2LinePool and InternalSymbolizer, since all of
+// them use the same output format.
+bool ParseSymbolizePCOutput(const char *str, SymbolizedStack *res) {
+  bool top_frame = true;
+  SymbolizedStack *last = res;
+  while (true) {
+    char *function_name = 0;
+    str = ExtractToken(str, "\n", &function_name);
+    CHECK(function_name);
+    if (function_name[0] == '\0') {
+      // There are no more frames.
+      InternalFree(function_name);
+      break;
+    }
+    SymbolizedStack *cur;
+    if (top_frame) {
+      cur = res;
+      top_frame = false;
+    } else {
+      cur = SymbolizedStack::New(res->info.address);
+      cur->info.FillModuleInfo(res->info.module, res->info.module_offset);
+      last->next = cur;
+      last = cur;
+    }
+
+    AddressInfo *info = &cur->info;
+    info->function = function_name;
+    // Parse <file>:<line>:<column> buffer. The file path may contain colons on
+    // Windows, so extract tokens from the right hand side first.
+    char *file_line_info = 0;
+    str = ExtractToken(str, "\n", &file_line_info);
+    CHECK(file_line_info);
+    // Parse the last :<int>, which must be there.
+    char *last_colon = internal_strrchr(file_line_info, ':');
+    CHECK(last_colon);
+    int line_or_column;
+    ExtractInt(last_colon + 1, "", &line_or_column);
+    *last_colon = '\0';
+    last_colon = internal_strrchr(file_line_info, ':');
+    if (last_colon && IsDigit(last_colon[1])) {
+      // If the colon before this one is followed by a digit, it must be the
+      // line number, and the previous parsed number was a column.
+      info->line = internal_atoll(last_colon + 1);
+      info->column = line_or_column;
+      *last_colon = '\0';
+    } else {
+      // Otherwise, we have line info but no column info.
+      info->line = line_or_column;
+      info->column = 0;
+    }
+    ExtractToken(file_line_info, "", &info->file);
+    InternalFree(file_line_info);
+
+    // Functions and filenames can be "??", in which case we write 0
+    // to address info to mark that names are unknown.
+    if (0 == internal_strcmp(info->function, "??")) {
+      InternalFree(info->function);
+      info->function = 0;
+    }
+    if (0 == internal_strcmp(info->file, "??")) {
+      InternalFree(info->file);
+      info->file = 0;
+    }
+  }
+
+  // If we got a function name, we probably had debug info.
+  return last->info.function != nullptr;
+}
+
+// Parses a two-line string in the following format:
+//   <symbol_name>
+//   <start_address> <size>
+// Used by LLVMSymbolizer and InternalSymbolizer.
+void ParseSymbolizeDataOutput(const char *str, DataInfo *info) {
+  str = ExtractToken(str, "\n", &info->name);
+  str = ExtractUptr(str, " ", &info->start);
+  str = ExtractUptr(str, "\n", &info->size);
+}
+
+bool LLVMSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
+  if (const char *buf = SendCommand(/*is_data*/ false, stack->info.module,
+                                    stack->info.module_offset)) {
+    return ParseSymbolizePCOutput(buf, stack);
+  }
+  return false;
+}
+
+bool LLVMSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
+  if (const char *buf =
+          SendCommand(/*is_data*/ true, info->module, info->module_offset)) {
+    ParseSymbolizeDataOutput(buf, info);
+    info->start += (addr - info->module_offset); // Add the base address.
+    return true;
+  }
+  return false;
+}
+
+const char *LLVMSymbolizer::SendCommand(bool is_data, const char *module_name,
+                                        uptr module_offset) {
+  CHECK(module_name);
+  internal_snprintf(buffer_, kBufferSize, "%s\"%s\" 0x%zx\n",
+                    is_data ? "DATA " : "", module_name, module_offset);
+  return symbolizer_process_->SendCommand(buffer_);
+}
+
+SymbolizerProcess::SymbolizerProcess(const char *path, bool use_forkpty)
+    : path_(path),
+      input_fd_(kInvalidFd),
+      output_fd_(kInvalidFd),
+      times_restarted_(0),
+      failed_to_start_(false),
+      reported_invalid_path_(false),
+      use_forkpty_(use_forkpty) {
+  CHECK(path_);
+  CHECK_NE(path_[0], '\0');
+}
+
+const char *SymbolizerProcess::SendCommand(const char *command) {
+  for (; times_restarted_ < kMaxTimesRestarted; times_restarted_++) {
+    // Start or restart symbolizer if we failed to send command to it.
+    if (const char *res = SendCommandImpl(command))
+      return res;
+    Restart();
+  }
+  if (!failed_to_start_) {
+    Report("WARNING: Failed to use and restart external symbolizer!\n");
+    failed_to_start_ = true;
+  }
+  return 0;
+}
+
+const char *SymbolizerProcess::SendCommandImpl(const char *command) {
+  if (input_fd_ == kInvalidFd || output_fd_ == kInvalidFd)
+      return 0;
+  if (!WriteToSymbolizer(command, internal_strlen(command)))
+      return 0;
+  if (!ReadFromSymbolizer(buffer_, kBufferSize))
+      return 0;
+  return buffer_;
+}
+
+bool SymbolizerProcess::Restart() {
+  if (input_fd_ != kInvalidFd)
+    CloseFile(input_fd_);
+  if (output_fd_ != kInvalidFd)
+    CloseFile(output_fd_);
+  return StartSymbolizerSubprocess();
+}
+
+bool SymbolizerProcess::ReadFromSymbolizer(char *buffer, uptr max_length) {
+  if (max_length == 0)
+    return true;
+  uptr read_len = 0;
+  while (true) {
+    uptr just_read = 0;
+    bool success = ReadFromFile(input_fd_, buffer + read_len,
+                                max_length - read_len - 1, &just_read);
+    // We can't read 0 bytes, as we don't expect external symbolizer to close
+    // its stdout.
+    if (!success || just_read == 0) {
+      Report("WARNING: Can't read from symbolizer at fd %d\n", input_fd_);
+      return false;
+    }
+    read_len += just_read;
+    if (ReachedEndOfOutput(buffer, read_len))
+      break;
+  }
+  buffer[read_len] = '\0';
+  return true;
+}
+
+bool SymbolizerProcess::WriteToSymbolizer(const char *buffer, uptr length) {
+  if (length == 0)
+    return true;
+  uptr write_len = 0;
+  bool success = WriteToFile(output_fd_, buffer, length, &write_len);
+  if (!success || write_len != length) {
+    Report("WARNING: Can't write to symbolizer at fd %d\n", output_fd_);
+    return false;
+  }
+  return true;
+}
+
 }  // namespace __sanitizer

lib/sanitizer_common/sanitizer_symbolizer_mac.cc

 
 bool DlAddrSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
   return false;
 }
 
 class AtosSymbolizerProcess : public SymbolizerProcess {
  public:
   explicit AtosSymbolizerProcess(const char *path, pid_t parent_pid)
-      : SymbolizerProcess(path, /*use_forkpty*/ true),
-        parent_pid_(parent_pid) {}
+      : SymbolizerProcess(path, /*use_forkpty*/ true) {
+    // Put the string command line argument in the object so that it outlives
+    // the call to GetArgV.
+    internal_snprintf(pid_str_, sizeof(pid_str_), "%d", parent_pid_);
+  }
 
  private:
   bool ReachedEndOfOutput(const char *buffer, uptr length) const override {
     return (length >= 1 && buffer[length - 1] == '\n');
   }
 
-  void ExecuteWithDefaultArgs(const char *path_to_binary) const override {
-    char pid_str[16];
-    internal_snprintf(pid_str, sizeof(pid_str), "%d", parent_pid_);
+  void GetArgV(const char *path_to_binary,
+               const char *(&argv)[kArgVMax]) const override {
+    int i = 0;
+    argv[i++] = path_to_binary;
+    argv[i++] = "-p";
+    argv[i++] = &pid_str_[0];
     if (GetMacosVersion() == MACOS_VERSION_MAVERICKS) {
       // On Mavericks atos prints a deprecation warning which we suppress by
       // passing -d. The warning isn't present on other OSX versions, even the
       // newer ones.
-      execl(path_to_binary, path_to_binary, "-p", pid_str, "-d", (char *)0);
-    } else {
-      execl(path_to_binary, path_to_binary, "-p", pid_str, (char *)0);
+      argv[i++] = "-d";
     }
+    argv[i++] = nullptr;
   }
 
-  pid_t parent_pid_;
+  char pid_str_[16];
 };
 
 static const char *kAtosErrorMessages[] = {
   "atos cannot examine process",
   "unable to get permission to examine process",
   "An admin user name and password is required",
   "could not load inserted library",
   "architecture mismatch between analysis process",

lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc

 #include "sanitizer_internal_defs.h"
 #include "sanitizer_linux.h"
 #include "sanitizer_placement_new.h"
 #include "sanitizer_procmaps.h"
 #include "sanitizer_symbolizer_internal.h"
 #include "sanitizer_symbolizer_libbacktrace.h"
 #include "sanitizer_symbolizer_mac.h"
 
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
+#if SANITIZER_MAC
+#include <util.h>  // for forkpty()
+#endif  // SANITIZER_MAC
+
 // C++ demangling function, as required by Itanium C++ ABI. This is weak,
 // because we do not require a C++ ABI library to be linked to a program
 // using sanitizers; if it's not present, we'll just use the mangled name.
 namespace __cxxabiv1 {
   extern "C" SANITIZER_WEAK_ATTRIBUTE
   char *__cxa_demangle(const char *mangled, char *buffer,
                                   size_t *length, int *status);
 }
const char *DemangleCXXABI(const char *name) {
   if (__cxxabiv1::__cxa_demangle)
     if (const char *demangled_name =
           __cxxabiv1::__cxa_demangle(name, 0, 0, 0))
       return demangled_name;
 
   return name;
 }
 
-// Parses one or more two-line strings in the following format:
-//   <function_name>
-//   <file_name>:<line_number>[:<column_number>]
-// Used by LLVMSymbolizer, Addr2LinePool and InternalSymbolizer, since all of
-// them use the same output format.
-static void ParseSymbolizePCOutput(const char *str, SymbolizedStack *res) {
-  bool top_frame = true;
-  SymbolizedStack *last = res;
-  while (true) {
-    char *function_name = 0;
-    str = ExtractToken(str, "\n", &function_name);
-    CHECK(function_name);
-    if (function_name[0] == '\0') {
-      // There are no more frames.
-      InternalFree(function_name);
-      break;
-    }
-    SymbolizedStack *cur;
-    if (top_frame) {
-      cur = res;
-      top_frame = false;
-    } else {
-      cur = SymbolizedStack::New(res->info.address);
-      cur->info.FillModuleInfo(res->info.module, res->info.module_offset);
-      last->next = cur;
-      last = cur;
-    }
-
-    AddressInfo *info = &cur->info;
-    info->function = function_name;
-    // Parse <file>:<line>:<column> buffer.
-    char *file_line_info = 0;
-    str = ExtractToken(str, "\n", &file_line_info);
-    CHECK(file_line_info);
-    const char *line_info = ExtractToken(file_line_info, ":", &info->file);
-    line_info = ExtractInt(line_info, ":", &info->line);
-    line_info = ExtractInt(line_info, "", &info->column);
-    InternalFree(file_line_info);
-
-    // Functions and filenames can be "??", in which case we write 0
-    // to address info to mark that names are unknown.
-    if (0 == internal_strcmp(info->function, "??")) {
-      InternalFree(info->function);
-      info->function = 0;
-    }
-    if (0 == internal_strcmp(info->file, "??")) {
-      InternalFree(info->file);
-      info->file = 0;
+bool SymbolizerProcess::StartSymbolizerSubprocess() {
+  if (!FileExists(path_)) {
+    if (!reported_invalid_path_) {
+      Report("WARNING: invalid path to external symbolizer!\n");
+      reported_invalid_path_ = true;
+    }
+    return false;
+
+  int pid;
+  if (use_forkpty_) {
+#if SANITIZER_MAC
+    fd_t fd = kInvalidFd;
+    // Use forkpty to disable buffering in the new terminal.
+    pid = forkpty(&fd, 0, 0, 0);
+    if (pid == -1) {
+      // forkpty() failed.
+      Report("WARNING: failed to fork external symbolizer (errno: %d)\n",
+             errno);
+      return false;
+    } else if (pid == 0) {
+      // Child subprocess.
+      const char *argv[kArgVMax];
+      GetArgV(path_, argv);
+      execv(path_, const_cast<char **>(&argv[0]));
+      internal__exit(1);
+    }
+
+    // Continue execution in parent process.
+    input_fd_ = output_fd_ = fd;
+
+    // Disable echo in the new terminal, disable CR.
+    struct termios termflags;
+    tcgetattr(fd, &termflags);
+    termflags.c_oflag &= ~ONLCR;
+    termflags.c_lflag &= ~ECHO;
+    tcsetattr(fd, TCSANOW, &termflags);
+#else  // SANITIZER_MAC
+    UNIMPLEMENTED();
+#endif  // SANITIZER_MAC
+    int *infd = NULL;
+    int *outfd = NULL;
+    // The client program may close its stdin and/or stdout and/or stderr
+    // thus allowing socketpair to reuse file descriptors 0, 1 or 2.
+    // In this case the communication between the forked processes may be
+    // broken if either the parent or the child tries to close or duplicate
+    // these descriptors. The loop below produces two pairs of file
+    // descriptors, each greater than 2 (stderr).
+    int sock_pair[5][2];
+    for (int i = 0; i < 5; i++) {
+      if (pipe(sock_pair[i]) == -1) {
+        for (int j = 0; j < i; j++) {
+          internal_close(sock_pair[j][0]);
+          internal_close(sock_pair[j][1]);
         }
+        Report("WARNING: Can't create a socket pair to start "
+               "external symbolizer (errno: %d)\n", errno);
+        return false;
+      } else if (sock_pair[i][0] > 2 && sock_pair[i][1] > 2) {
+        if (infd == NULL) {
+          infd = sock_pair[i];
+        } else {
+          outfd = sock_pair[i];
+          for (int j = 0; j < i; j++) {
+            if (sock_pair[j] == infd) continue;
+            internal_close(sock_pair[j][0]);
+            internal_close(sock_pair[j][1]);
           }
+          break;
         }
-
-// Parses a two-line string in the following format:
-//   <symbol_name>
-//   <start_address> <size>
-// Used by LLVMSymbolizer and InternalSymbolizer.
-static void ParseSymbolizeDataOutput(const char *str, DataInfo *info) {
-  str = ExtractToken(str, "\n", &info->name);
-  str = ExtractUptr(str, " ", &info->start);
-  str = ExtractUptr(str, "\n", &info->size);
-}
-
-// For now we assume the following protocol:
-// For each request of the form
-//   <module_name> <module_offset>
-// passed to STDIN, external symbolizer prints to STDOUT response:
-//   <function_name>
-//   <file_name>:<line_number>:<column_number>
-//   <function_name>
-//   <file_name>:<line_number>:<column_number>
-//   ...
-//   <empty line>
-class LLVMSymbolizerProcess : public SymbolizerProcess {
- public:
-  explicit LLVMSymbolizerProcess(const char *path) : SymbolizerProcess(path) {}
-
- private:
-  bool ReachedEndOfOutput(const char *buffer, uptr length) const override {
-    // Empty line marks the end of llvm-symbolizer output.
-    return length >= 2 && buffer[length - 1] == '\n' &&
-           buffer[length - 2] == '\n';
-  }
-
-  void ExecuteWithDefaultArgs(const char *path_to_binary) const override {
-#if defined(__x86_64h__)
-    const char* const kSymbolizerArch = "--default-arch=x86_64h";
-#elif defined(__x86_64__)
-    const char* const kSymbolizerArch = "--default-arch=x86_64";
-#elif defined(__i386__)
-    const char* const kSymbolizerArch = "--default-arch=i386";
-#elif defined(__powerpc64__) && defined(__BIG_ENDIAN__)
-    const char* const kSymbolizerArch = "--default-arch=powerpc64";
-#elif defined(__powerpc64__) && defined(__LITTLE_ENDIAN__)
-    const char* const kSymbolizerArch = "--default-arch=powerpc64le";
-#else
-    const char* const kSymbolizerArch = "--default-arch=unknown";
-#endif
-
-    const char *const inline_flag = common_flags()->symbolize_inline_frames
-                                        ? "--inlining=true"
-                                        : "--inlining=false";
-    execl(path_to_binary, path_to_binary, inline_flag, kSymbolizerArch,
-          (char *)0);
       }
-};
-
-class LLVMSymbolizer : public SymbolizerTool {
- public:
-  explicit LLVMSymbolizer(const char *path, LowLevelAllocator *allocator)
-      : symbolizer_process_(new(*allocator) LLVMSymbolizerProcess(path)) {}
-
-  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override {
-    if (const char *buf = SendCommand(/*is_data*/ false, stack->info.module,
-                                      stack->info.module_offset)) {
-      ParseSymbolizePCOutput(buf, stack);
-      return true;
-    }
-    return false;
     }
+    CHECK(infd);
+    CHECK(outfd);
 
-  bool SymbolizeData(uptr addr, DataInfo *info) override {
-    if (const char *buf =
-            SendCommand(/*is_data*/ true, info->module, info->module_offset)) {
-      ParseSymbolizeDataOutput(buf, info);
-      info->start += (addr - info->module_offset);  // Add the base address.
-      return true;
-    }
+    // Real fork() may call user callbacks registered with pthread_atfork().
+    pid = internal_fork();
+    if (pid == -1) {
+      // Fork() failed.
+      internal_close(infd[0]);
+      internal_close(infd[1]);
+      internal_close(outfd[0]);
+      internal_close(outfd[1]);
+      Report("WARNING: failed to fork external symbolizer "
+             " (errno: %d)\n", errno);
+      return false;
+    } else if (pid == 0) {
+      // Child subprocess.
+      internal_close(STDOUT_FILENO);
+      internal_close(STDIN_FILENO);
+      internal_dup2(outfd[0], STDIN_FILENO);
+      internal_dup2(infd[1], STDOUT_FILENO);
+      internal_close(outfd[0]);
+      internal_close(outfd[1]);
+      internal_close(infd[0]);
+      internal_close(infd[1]);
+      for (int fd = sysconf(_SC_OPEN_MAX); fd > 2; fd--)
+        internal_close(fd);
+      const char *argv[kArgVMax];
+      GetArgV(path_, argv);
+      execv(path_, const_cast<char **>(&argv[0]));
+      internal__exit(1);
+    }
+
+    // Continue execution in parent process.
+    internal_close(outfd[0]);
+    internal_close(infd[1]);
+    input_fd_ = infd[0];
+    output_fd_ = outfd[1];
+  }
+
+  // Check that symbolizer subprocess started successfully.
+  int pid_status;
+  SleepForMillis(kSymbolizerStartupTimeMillis);
+  int exited_pid = waitpid(pid, &pid_status, WNOHANG);
+  if (exited_pid != 0) {
+    // Either waitpid failed, or child has already exited.
+    Report("WARNING: external symbolizer didn't start up correctly!\n");
     return false;
   }
 
- private:
-  const char *SendCommand(bool is_data, const char *module_name,
-                          uptr module_offset) {
-    CHECK(module_name);
-    internal_snprintf(buffer_, kBufferSize, "%s\"%s\" 0x%zx\n",
-                      is_data ? "DATA " : "", module_name, module_offset);
-    return symbolizer_process_->SendCommand(buffer_);
-  }
+  return true;
 
-  LLVMSymbolizerProcess *symbolizer_process_;
-  static const uptr kBufferSize = 16 * 1024;
-  char buffer_[kBufferSize];
-};
-
 class Addr2LineProcess : public SymbolizerProcess {
  public:
   Addr2LineProcess(const char *path, const char *module_name)
       : SymbolizerProcess(path), module_name_(internal_strdup(module_name)) {}
 
   const char *module_name() const { return module_name_; }
 
  private:
   bool ReachedEndOfOutput(const char *buffer, uptr length) const override {
     // Output should consist of two lines.
     int num_lines = 0;
     for (uptr i = 0; i < length; ++i) {
       if (buffer[i] == '\n')
         num_lines++;
       if (num_lines >= 2)
         return true;
     }
     return false;
   }
 
-  void ExecuteWithDefaultArgs(const char *path_to_binary) const override {
-    execl(path_to_binary, path_to_binary, "-Cfe", module_name_, (char *)0);
+  void GetArgV(const char *path_to_binary,
+               const char *(&argv)[kArgVMax]) const override {
+    int i = 0;
+    argv[i++] = path_to_binary;
+    argv[i++] = "-Cfe";
+    argv[i++] = module_name_;
+    argv[i++] = nullptr;
   }
 
   const char *module_name_;  // Owned, leaked.
 };
 
 class Addr2LinePool : public SymbolizerTool {
  public:
   explicit Addr2LinePool(const char *addr2line_path,

lib/sanitizer_common/sanitizer_symbolizer_process_libcdep.cc

-//===-- sanitizer_symbolizer_process_libcdep.cc ---------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// Implementation of SymbolizerProcess used by external symbolizers.
-//
-//===----------------------------------------------------------------------===//
-
-#include "sanitizer_platform.h"
-#if SANITIZER_POSIX
-#include "sanitizer_posix.h"
-#include "sanitizer_symbolizer_internal.h"
-
-#include <errno.h>
-#include <stdlib.h>
-#include <sys/wait.h>
-#include <unistd.h>
-
-#if SANITIZER_MAC
-#include <util.h>  // for forkpty()
-#endif  // SANITIZER_MAC
-
-namespace __sanitizer {
-
-SymbolizerProcess::SymbolizerProcess(const char *path, bool use_forkpty)
-    : path_(path),
-      input_fd_(kInvalidFd),
-      output_fd_(kInvalidFd),
-      times_restarted_(0),
-      failed_to_start_(false),
-      reported_invalid_path_(false),
-      use_forkpty_(use_forkpty) {
-  CHECK(path_);
-  CHECK_NE(path_[0], '\0');
-}
-
-const char *SymbolizerProcess::SendCommand(const char *command) {
-  for (; times_restarted_ < kMaxTimesRestarted; times_restarted_++) {
-    // Start or restart symbolizer if we failed to send command to it.
-    if (const char *res = SendCommandImpl(command))
-      return res;
-    Restart();
-  }
-  if (!failed_to_start_) {
-    Report("WARNING: Failed to use and restart external symbolizer!\n");
-    failed_to_start_ = true;
-  }
-  return 0;
-}
-
-bool SymbolizerProcess::Restart() {
-  if (input_fd_ != kInvalidFd)
-    CloseFile(input_fd_);
-  if (output_fd_ != kInvalidFd)
-    CloseFile(output_fd_);
-  return StartSymbolizerSubprocess();
-}
-
-const char *SymbolizerProcess::SendCommandImpl(const char *command) {
-  if (input_fd_ == kInvalidFd || output_fd_ == kInvalidFd)
-      return 0;
-  if (!WriteToSymbolizer(command, internal_strlen(command)))
-      return 0;
-  if (!ReadFromSymbolizer(buffer_, kBufferSize))
-      return 0;
-  return buffer_;
-}
-
-bool SymbolizerProcess::ReadFromSymbolizer(char *buffer, uptr max_length) {
-  if (max_length == 0)
-    return true;
-  uptr read_len = 0;
-  while (true) {
-    uptr just_read = 0;
-    bool success = ReadFromFile(input_fd_, buffer + read_len,
-                                max_length - read_len - 1, &just_read);
-    // We can't read 0 bytes, as we don't expect external symbolizer to close
-    // its stdout.
-    if (!success || just_read == 0) {
-      Report("WARNING: Can't read from symbolizer at fd %d\n", input_fd_);
-      return false;
-    }
-    read_len += just_read;
-    if (ReachedEndOfOutput(buffer, read_len))
-      break;
-  }
-  buffer[read_len] = '\0';
-  return true;
-}
-
-bool SymbolizerProcess::WriteToSymbolizer(const char *buffer, uptr length) {
-  if (length == 0)
-    return true;
-  uptr write_len = 0;
-  bool success = WriteToFile(output_fd_, buffer, length, &write_len);
-  if (!success || write_len != length) {
-    Report("WARNING: Can't write to symbolizer at fd %d\n", output_fd_);
-    return false;
-  }
-  return true;
-}
-
-bool SymbolizerProcess::StartSymbolizerSubprocess() {
-  if (!FileExists(path_)) {
-    if (!reported_invalid_path_) {
-      Report("WARNING: invalid path to external symbolizer!\n");
-      reported_invalid_path_ = true;
-    }
-    return false;
-  }
-
-  int pid;
-  if (use_forkpty_) {
-#if SANITIZER_MAC
-    fd_t fd = kInvalidFd;
-    // Use forkpty to disable buffering in the new terminal.
-    pid = forkpty(&fd, 0, 0, 0);
-    if (pid == -1) {
-      // forkpty() failed.
-      Report("WARNING: failed to fork external symbolizer (errno: %d)\n",
-             errno);
-      return false;
-    } else if (pid == 0) {
-      // Child subprocess.
-      ExecuteWithDefaultArgs(path_);
-      internal__exit(1);
-    }
-
-    // Continue execution in parent process.
-    input_fd_ = output_fd_ = fd;
-
-    // Disable echo in the new terminal, disable CR.
-    struct termios termflags;
-    tcgetattr(fd, &termflags);
-    termflags.c_oflag &= ~ONLCR;
-    termflags.c_lflag &= ~ECHO;
-    tcsetattr(fd, TCSANOW, &termflags);
-#else  // SANITIZER_MAC
-    UNIMPLEMENTED();
-#endif  // SANITIZER_MAC
-  } else {
-    int *infd = NULL;
-    int *outfd = NULL;
-    // The client program may close its stdin and/or stdout and/or stderr
-    // thus allowing socketpair to reuse file descriptors 0, 1 or 2.
-    // In this case the communication between the forked processes may be
-    // broken if either the parent or the child tries to close or duplicate
-    // these descriptors. The loop below produces two pairs of file
-    // descriptors, each greater than 2 (stderr).
-    int sock_pair[5][2];
-    for (int i = 0; i < 5; i++) {
-      if (pipe(sock_pair[i]) == -1) {
-        for (int j = 0; j < i; j++) {
-          internal_close(sock_pair[j][0]);
-          internal_close(sock_pair[j][1]);
-        }
-        Report("WARNING: Can't create a socket pair to start "
-               "external symbolizer (errno: %d)\n", errno);
-        return false;
-      } else if (sock_pair[i][0] > 2 && sock_pair[i][1] > 2) {
-        if (infd == NULL) {
-          infd = sock_pair[i];
-        } else {
-          outfd = sock_pair[i];
-          for (int j = 0; j < i; j++) {
-            if (sock_pair[j] == infd) continue;
-            internal_close(sock_pair[j][0]);
-            internal_close(sock_pair[j][1]);
-          }
-          break;
-        }
-      }
-    }
-    CHECK(infd);
-    CHECK(outfd);
-
-    // Real fork() may call user callbacks registered with pthread_atfork().
-    pid = internal_fork();
-    if (pid == -1) {
-      // Fork() failed.
-      internal_close(infd[0]);
-      internal_close(infd[1]);
-      internal_close(outfd[0]);
-      internal_close(outfd[1]);
-      Report("WARNING: failed to fork external symbolizer "
-             " (errno: %d)\n", errno);
-      return false;
-    } else if (pid == 0) {
-      // Child subprocess.
-      internal_close(STDOUT_FILENO);
-      internal_close(STDIN_FILENO);
-      internal_dup2(outfd[0], STDIN_FILENO);
-      internal_dup2(infd[1], STDOUT_FILENO);
-      internal_close(outfd[0]);
-      internal_close(outfd[1]);
-      internal_close(infd[0]);
-      internal_close(infd[1]);
-      for (int fd = sysconf(_SC_OPEN_MAX); fd > 2; fd--)
-        internal_close(fd);
-      ExecuteWithDefaultArgs(path_);
-      internal__exit(1);
-    }
-
-    // Continue execution in parent process.
-    internal_close(outfd[0]);
-    internal_close(infd[1]);
-    input_fd_ = infd[0];
-    output_fd_ = outfd[1];
-  }
-
-  // Check that symbolizer subprocess started successfully.
-  int pid_status;
-  SleepForMillis(kSymbolizerStartupTimeMillis);
-  int exited_pid = waitpid(pid, &pid_status, WNOHANG);
-  if (exited_pid != 0) {
-    // Either waitpid failed, or child has already exited.
-    Report("WARNING: external symbolizer didn't start up correctly!\n");
-    return false;
-  }
-
-  return true;
-}
-
-}  // namespace __sanitizer
-
-#endif  // SANITIZER_POSIX

lib/sanitizer_common/sanitizer_symbolizer_win.h

-//===-- sanitizer_symbolizer_win.h ------------------------------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// Header file for the Windows symbolizer tool.
-//
-//===----------------------------------------------------------------------===//
-#ifndef SANITIZER_SYMBOLIZER_WIN_H
-#define SANITIZER_SYMBOLIZER_WIN_H
-
-#include "sanitizer_symbolizer_internal.h"
-
-namespace __sanitizer {
-
-class WinSymbolizerTool : public SymbolizerTool {
- public:
-  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override;
-  bool SymbolizeData(uptr addr, DataInfo *info) override {
-    return false;
-  }
-  const char *Demangle(const char *name) override;
-};
-
-}  // namespace __sanitizer
-
-#endif  // SANITIZER_SYMBOLIZER_WIN_H

lib/sanitizer_common/sanitizer_symbolizer_win.cc

 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_platform.h"
 #if SANITIZER_WINDOWS
 #include <windows.h>
 #include <dbghelp.h>
 #pragma comment(lib, "dbghelp.lib")
 
-#include "sanitizer_symbolizer_win.h"
 #include "sanitizer_symbolizer_internal.h"
 
 namespace __sanitizer {
 
 namespace {
 
+class WinSymbolizerTool : public SymbolizerTool {
+ public:
+  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override;
+  bool SymbolizeData(uptr addr, DataInfo *info) override {
+    return false;
+  }
+  const char *Demangle(const char *name) override;
+};
+
 bool is_dbghelp_initialized = false;
 
 bool TrySymInitialize() {
   SymSetOptions(SYMOPT_DEFERRED_LOADS | SYMOPT_UNDNAME | SYMOPT_LOAD_LINES);
   return SymInitialize(GetCurrentProcess(), 0, TRUE);
   // FIXME: We don't call SymCleanup() on exit yet - should we?
 }
 
bool WinSymbolizerTool::SymbolizePC(uptr addr, SymbolizedStack *frame) {
   BOOL got_fileline = SymGetLineFromAddr64(GetCurrentProcess(), (DWORD64)addr,
                                            &unused, &line_info);
   frame->info.function = internal_strdup(symbol->Name);
   frame->info.function_offset = (uptr)offset;
   if (got_fileline) {
     frame->info.file = internal_strdup(line_info.FileName);
     frame->info.line = line_info.LineNumber;
   }
-  return true;
+  // Only consider this a successful symbolization attempt if we got file info.
+  // Otherwise, try llvm-symbolizer.
+  return got_fileline;
 }
 
 const char *WinSymbolizerTool::Demangle(const char *name) {
   CHECK(is_dbghelp_initialized);
   static char demangle_buffer[1000];
   if (name[0] == '\01' &&
       UnDecorateSymbolName(name + 1, demangle_buffer, sizeof(demangle_buffer),
                            UNDNAME_NAME_ONLY))
     return demangle_buffer;
   else
     return name;
 }
 
 const char *Symbolizer::PlatformDemangle(const char *name) {
   return name;
 }
 
 void Symbolizer::PlatformPrepareForSandboxing() {
   // Do nothing.
 }
 
+namespace {
+struct ScopedHandle {
+  ScopedHandle() : h_(nullptr) {}
+  explicit ScopedHandle(HANDLE h) : h_(h) {}
+  ~ScopedHandle() {
+    if (h_)
+      ::CloseHandle(h_);
+  }
+  HANDLE get() { return h_; }
+  HANDLE *receive() { return &h_; }
+  HANDLE release() {
+    HANDLE h = h_;
+    h_ = nullptr;
+    return h;
+  }
+  HANDLE h_;
+};
+} // namespace
+
+bool SymbolizerProcess::StartSymbolizerSubprocess() {
+  // Create inherited pipes for stdin and stdout.
+  ScopedHandle stdin_read, stdin_write;
+  ScopedHandle stdout_read, stdout_write;
+  SECURITY_ATTRIBUTES attrs;
+  attrs.nLength = sizeof(SECURITY_ATTRIBUTES);
+  attrs.bInheritHandle = TRUE;
+  attrs.lpSecurityDescriptor = nullptr;
+  if (!::CreatePipe(stdin_read.receive(), stdin_write.receive(), &attrs, 0) ||
+      !::CreatePipe(stdout_read.receive(), stdout_write.receive(), &attrs, 0))
+    return false;
+
+  // Don't inherit the writing end of stdin or the reading end of stdout.
+  if (!SetHandleInformation(stdin_write.get(), HANDLE_FLAG_INHERIT, 0) ||
+      !SetHandleInformation(stdout_read.get(), HANDLE_FLAG_INHERIT, 0))
+    return false;
+
+  // Compute the command line. Wrap double quotes around everything.
+  const char *argv[kArgVMax];
+  GetArgV(path_, argv);
+  InternalScopedString command_line(kMaxPathLength * 3);
+  for (int i = 0; argv[i]; i++) {
+    const char *arg = argv[i];
+    int arglen = internal_strlen(arg);
+    // Check that tool command lines are simple and that complete escaping is
+    // unnecessary.
+    CHECK(!internal_strchr(arg, '"') && "quotes in args unsupported");
+    CHECK(!internal_strstr(arg, "\\\\") &&
+          "double backslashes in args unsupported");
+    CHECK(arglen > 0 && arg[arglen - 1] != '\\' &&
+          "args ending in backslash and empty args unsupported");
+    command_line.append("\"%s\" ", arg);
+  }
+  VReport(3, "Launching symbolizer command: %s\n", command_line.data());
+
+  // Launch llvm-symbolizer with stdin and stdout redirected.
+  STARTUPINFOA si;
+  memset(&si, 0, sizeof(si));
+  si.cb = sizeof(si);
+  si.dwFlags |= STARTF_USESTDHANDLES;
+  si.hStdInput = stdin_read.get();
+  si.hStdOutput = stdout_write.get();
+  PROCESS_INFORMATION pi;
+  memset(&pi, 0, sizeof(pi));
+  if (!CreateProcessA(path_,               // Executable
+                      command_line.data(), // Command line
+                      nullptr,             // Process handle not inheritable
+                      nullptr,             // Thread handle not inheritable
+                      TRUE,                // Set handle inheritance to TRUE
+                      0,                   // Creation flags
+                      nullptr,             // Use parent's environment block
+                      nullptr,             // Use parent's starting directory
+                      &si, &pi)) {
+    VReport(2, "WARNING: %s failed to create process for %s (error code: %d)\n",
+            SanitizerToolName, path_, GetLastError());
+    return false;
+  }
+
+  // Process creation succeeded, so transfer handle ownership into the fields.
+  input_fd_ = stdout_read.release();
+  output_fd_ = stdin_write.release();
+
+  // The llvm-symbolizer process is responsible for quitting itself when the
+  // stdin pipe is closed, so we don't need these handles. Close them to prevent
+  // leaks. If we ever want to try to kill the symbolizer process from the
+  // parent, we'll want to hang on to these handles.
+  CloseHandle(pi.hProcess);
+  CloseHandle(pi.hThread);
+  return true;
+}
+
+static void ChooseSymbolizerTools(IntrusiveList<SymbolizerTool> *list,
+                                  LowLevelAllocator *allocator) {
+  if (!common_flags()->symbolize) {
+    VReport(2, "Symbolizer is disabled.\n");
+    return;
+  }
+
+  // Add llvm-symbolizer in case the binary has dwarf.
+  const char *user_path = common_flags()->external_symbolizer_path;
+  const char *path =
+      user_path ? user_path : FindPathToBinary("llvm-symbolizer.exe");
+  if (path) {
+    VReport(2, "Using llvm-symbolizer at %spath: %s\n",
+            user_path ? "user-specified " : "", path);
+    list->push_back(new(*allocator) LLVMSymbolizer(path, allocator));
+  } else {
+    if (user_path && user_path[0] == '\0') {
+      VReport(2, "External symbolizer is explicitly disabled.\n");
+    } else {
+      VReport(2, "External symbolizer is not present.\n");
+    }
+  }
+
+  // Add the dbghelp based symbolizer.
+  list->push_back(new(*allocator) WinSymbolizerTool());
+}
+
 Symbolizer *Symbolizer::PlatformInit() {
   IntrusiveList<SymbolizerTool> list;
   list.clear();
-  list.push_back(new(symbolizer_allocator_) WinSymbolizerTool());
+  ChooseSymbolizerTools(&list, &symbolizer_allocator_);
+
   return new(symbolizer_allocator_) Symbolizer(list);
 }
 
 }  // namespace __sanitizer
 
 #endif  // _WIN32

test/asan/CMakeLists.txt

 set(ASAN_LIT_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 
 set(ASAN_TESTSUITES)
 set(ASAN_DYNAMIC_TESTSUITES)
 
 macro(get_bits_for_arch arch bits)
   if (${arch} MATCHES "i386|i686|arm|mips|mipsel")
     set(${bits} 32)
   elseif (${arch} MATCHES "x86_64|powerpc64|powerpc64le|aarch64|mips64|mips64el")
     set(${bits} 64)
   else()
     message(FATAL_ERROR "Unknown target architecture: ${arch}")
   endif()
 endmacro()
 
+set(ASAN_TEST_DEPS ${SANITIZER_COMMON_LIT_TEST_DEPS})
+if(NOT COMPILER_RT_STANDALONE_BUILD)
+  list(APPEND ASAN_TEST_DEPS asan)
+  if(WIN32 AND COMPILER_RT_HAS_LLD_SOURCES)
+    list(APPEND ASAN_TEST_DEPS
+      lld
+    )
+  endif()
+endif()
+set(ASAN_DYNAMIC_TEST_DEPS ${ASAN_TEST_DEPS})
+
 foreach(arch ${ASAN_SUPPORTED_ARCH})
   if(ANDROID)
     set(ASAN_TEST_TARGET_ARCH ${arch}-android)
   else()
     set(ASAN_TEST_TARGET_ARCH ${arch})
   endif()
   string(TOLOWER "-${arch}-${OS_NAME}" ASAN_TEST_CONFIG_SUFFIX)
   get_bits_for_arch(${arch} ASAN_TEST_BITS)
if(COMPILER_RT_ASAN_HAS_STATIC_RUNTIME)
     configure_lit_site_cfg(
       ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
       ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg)
     list(APPEND ASAN_DYNAMIC_TESTSUITES
       ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME})
   endif()
 endforeach()
 
-set(ASAN_TEST_DEPS ${SANITIZER_COMMON_LIT_TEST_DEPS})
-if(NOT COMPILER_RT_STANDALONE_BUILD)
-  list(APPEND ASAN_TEST_DEPS asan)
-endif()
-set(ASAN_DYNAMIC_TEST_DEPS ${ASAN_TEST_DEPS})
-
 # Add unit tests.
 if(COMPILER_RT_INCLUDE_TESTS)
   set(ASAN_TEST_DYNAMIC False)
   configure_lit_site_cfg(
     ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.site.cfg.in
     ${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg)
   if(COMPILER_RT_ASAN_HAS_STATIC_RUNTIME)
     set(ASAN_TEST_DYNAMIC True)

test/asan/TestCases/Windows/fuse-lld.cc

+// If we have LLD, see that things more or less work.
+//
+// REQUIRES: lld
+//
+// FIXME: Use -fuse-ld=lld after the old COFF linker is removed.
+// FIXME: Test will fail until we add flags for requesting dwarf or cv.
+// RUNX: %clangxx_asan -O2 %s -o %t.exe -fuse-ld=lld -Wl,-debug
+// RUN: %clangxx_asan -c -O2 %s -o %t.o -gdwarf
+// RUN: lld-link2 %t.o -out:%t.exe -debug -defaultlib:libcmt %asan_lib %asan_cxx_lib
+// RUN: not %run %t.exe 2>&1 | FileCheck %s
+
+#include <stdlib.h>
+
+int main() {
+  char *x = (char*)malloc(10 * sizeof(char));
+  free(x);
+  return x[5];
+  // CHECK: heap-use-after-free
+  // CHECK: free
+  // CHECK: main{{.*}}fuse-lld.cc:[[@LINE-4]]:3
+  // CHECK: malloc
+  // CHECK: main{{.*}}fuse-lld.cc:[[@LINE-7]]:20
+}

test/asan/TestCases/Windows/null_deref.cc

 // RUN: %clangxx_asan -O0 %s -o %t && not %run %t 2>&1 | FileCheck %s
 // FIXME: merge this with the common null_deref test when we can run common
 // tests on Windows.
 
 __attribute__((noinline))
 static void NullDeref(int *ptr) {
   // CHECK: ERROR: AddressSanitizer: access-violation on unknown address
   // CHECK:   {{0x0*000.. .*pc 0x.*}}
   ptr[10]++;  // BOOM
 }
 int main() {
   NullDeref((int*)0);
-  // CHECK: {{    #1 0x.* in main.*null_deref.cc:}}[[@LINE-1]]
+  // CHECK: {{    #1 0x.* in main.*null_deref.cc:}}[[@LINE-1]]:3
   // CHECK: AddressSanitizer can not provide additional info.
 }

test/asan/TestCases/Windows/report_after_syminitialize.cc

-// RUN: %clangxx_asan -O0 %s -o %t && not %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_asan -O0 %s -o %t
+// RUN: env ASAN_OPTIONS=external_symbolizer_path=asdf not %run %t 2>&1 | FileCheck %s
 
 #include <windows.h>
 #include <dbghelp.h>
 
 int main() {
   // Make sure the RTL recovers from "no options enabled" dbghelp setup.
   SymSetOptions(0);
 
   // Make sure the RTL recovers from "fInvadeProcess=FALSE".
   if (!SymInitialize(GetCurrentProcess(), 0, FALSE))
     return 42;
 
   *(volatile int*)0 = 42;
   // CHECK: ERROR: AddressSanitizer: access-violation on unknown address
+  // CHECK-NEXT: {{WARNING: Failed to use and restart external symbolizer}}
   // CHECK-NEXT: {{WARNING: .*DbgHelp}}
-  // CHECK: {{#0 0x.* in main.*report_after_syminitialize.cc:}}[[@LINE-3]]
+  // CHECK: {{#0 0x.* in main.*report_after_syminitialize.cc:}}[[@LINE-4]]
   // CHECK: AddressSanitizer can not provide additional info.
 }