1//===-- sanitizer_symbolizer_posix_libcdep.cpp ----------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file is shared between AddressSanitizer and ThreadSanitizer
10// run-time libraries.
11// POSIX-specific implementation of symbolizer parts.
12//===----------------------------------------------------------------------===//
13
14#include "sanitizer_platform.h"
15#if SANITIZER_POSIX
16#include "sanitizer_allocator_internal.h"
17#include "sanitizer_common.h"
18#include "sanitizer_file.h"
19#include "sanitizer_flags.h"
20#include "sanitizer_internal_defs.h"
21#include "sanitizer_linux.h"
22#include "sanitizer_placement_new.h"
23#include "sanitizer_posix.h"
24#include "sanitizer_procmaps.h"
25#include "sanitizer_symbolizer_internal.h"
26#include "sanitizer_symbolizer_libbacktrace.h"
27#include "sanitizer_symbolizer_mac.h"
28
29#include <dlfcn.h>   // for dlsym()
30#include <errno.h>
31#include <stdint.h>
32#include <stdlib.h>
33#include <sys/wait.h>
34#include <unistd.h>
35
36// C++ demangling function, as required by Itanium C++ ABI. This is weak,
37// because we do not require a C++ ABI library to be linked to a program
38// using sanitizers; if it's not present, we'll just use the mangled name.
39namespace __cxxabiv1 {
40  extern "C" SANITIZER_WEAK_ATTRIBUTE
41  char *__cxa_demangle(const char *mangled, char *buffer,
42                                  size_t *length, int *status);
43}
44
45namespace __sanitizer {
46
47// Attempts to demangle the name via __cxa_demangle from __cxxabiv1.
48const char *DemangleCXXABI(const char *name) {
49  // FIXME: __cxa_demangle aggressively insists on allocating memory.
50  // There's not much we can do about that, short of providing our
51  // own demangler (libc++abi's implementation could be adapted so that
52  // it does not allocate). For now, we just call it anyway, and we leak
53  // the returned value.
54  if (&__cxxabiv1::__cxa_demangle)
55    if (const char *demangled_name =
56          __cxxabiv1::__cxa_demangle(name, 0, 0, 0))
57      return demangled_name;
58
59  return name;
60}
61
62// As of now, there are no headers for the Swift runtime. Once they are
63// present, we will weakly link since we do not require Swift runtime to be
64// linked.
65typedef char *(*swift_demangle_ft)(const char *mangledName,
66                                   size_t mangledNameLength, char *outputBuffer,
67                                   size_t *outputBufferSize, uint32_t flags);
68static swift_demangle_ft swift_demangle_f;
69
70// This must not happen lazily at symbolication time, because dlsym uses
71// malloc and thread-local storage, which is not a good thing to do during
72// symbolication.
73static void InitializeSwiftDemangler() {
74  swift_demangle_f = (swift_demangle_ft)dlsym(RTLD_DEFAULT, "swift_demangle");
75  (void)dlerror(); // Cleanup error message in case of failure
76}
77
78// Attempts to demangle a Swift name. The demangler will return nullptr if a
79// non-Swift name is passed in.
80const char *DemangleSwift(const char *name) {
81  if (!name) return nullptr;
82
83  // Check if we are dealing with a Swift mangled name first.
84  if (name[0] != '_' || name[1] != 'T') {
85    return nullptr;
86  }
87
88  if (swift_demangle_f)
89    return swift_demangle_f(name, internal_strlen(name), 0, 0, 0);
90
91  return nullptr;
92}
93
94const char *DemangleSwiftAndCXX(const char *name) {
95  if (!name) return nullptr;
96  if (const char *swift_demangled_name = DemangleSwift(name))
97    return swift_demangled_name;
98  return DemangleCXXABI(name);
99}
100
101static bool CreateTwoHighNumberedPipes(int *infd_, int *outfd_) {
102  int *infd = NULL;
103  int *outfd = NULL;
104  // The client program may close its stdin and/or stdout and/or stderr
105  // thus allowing socketpair to reuse file descriptors 0, 1 or 2.
106  // In this case the communication between the forked processes may be
107  // broken if either the parent or the child tries to close or duplicate
108  // these descriptors. The loop below produces two pairs of file
109  // descriptors, each greater than 2 (stderr).
110  int sock_pair[5][2];
111  for (int i = 0; i < 5; i++) {
112    if (pipe(sock_pair[i]) == -1) {
113      for (int j = 0; j < i; j++) {
114        internal_close(sock_pair[j][0]);
115        internal_close(sock_pair[j][1]);
116      }
117      return false;
118    } else if (sock_pair[i][0] > 2 && sock_pair[i][1] > 2) {
119      if (infd == NULL) {
120        infd = sock_pair[i];
121      } else {
122        outfd = sock_pair[i];
123        for (int j = 0; j < i; j++) {
124          if (sock_pair[j] == infd) continue;
125          internal_close(sock_pair[j][0]);
126          internal_close(sock_pair[j][1]);
127        }
128        break;
129      }
130    }
131  }
132  CHECK(infd);
133  CHECK(outfd);
134  infd_[0] = infd[0];
135  infd_[1] = infd[1];
136  outfd_[0] = outfd[0];
137  outfd_[1] = outfd[1];
138  return true;
139}
140
141bool SymbolizerProcess::StartSymbolizerSubprocess() {
142  if (!FileExists(path_)) {
143    if (!reported_invalid_path_) {
144      Report("WARNING: invalid path to external symbolizer!\n");
145      reported_invalid_path_ = true;
146    }
147    return false;
148  }
149
150  const char *argv[kArgVMax];
151  GetArgV(path_, argv);
152  pid_t pid;
153
154  if (use_posix_spawn_) {
155#if SANITIZER_MAC
156    fd_t fd = internal_spawn(argv, &pid);
157    if (fd == kInvalidFd) {
158      Report("WARNING: failed to spawn external symbolizer (errno: %d)\n",
159             errno);
160      return false;
161    }
162
163    input_fd_ = fd;
164    output_fd_ = fd;
165#else  // SANITIZER_MAC
166    UNIMPLEMENTED();
167#endif  // SANITIZER_MAC
168  } else {
169    fd_t infd[2] = {}, outfd[2] = {};
170    if (!CreateTwoHighNumberedPipes(infd, outfd)) {
171      Report("WARNING: Can't create a socket pair to start "
172             "external symbolizer (errno: %d)\n", errno);
173      return false;
174    }
175
176    pid = StartSubprocess(path_, argv, /* stdin */ outfd[0],
177                          /* stdout */ infd[1]);
178    if (pid < 0) {
179      internal_close(infd[0]);
180      internal_close(outfd[1]);
181      return false;
182    }
183
184    input_fd_ = infd[0];
185    output_fd_ = outfd[1];
186  }
187
188  CHECK_GT(pid, 0);
189
190  // Check that symbolizer subprocess started successfully.
191  SleepForMillis(kSymbolizerStartupTimeMillis);
192  if (!IsProcessRunning(pid)) {
193    // Either waitpid failed, or child has already exited.
194    Report("WARNING: external symbolizer didn't start up correctly!\n");
195    return false;
196  }
197
198  return true;
199}
200
201class Addr2LineProcess : public SymbolizerProcess {
202 public:
203  Addr2LineProcess(const char *path, const char *module_name)
204      : SymbolizerProcess(path), module_name_(internal_strdup(module_name)) {}
205
206  const char *module_name() const { return module_name_; }
207
208 private:
209  void GetArgV(const char *path_to_binary,
210               const char *(&argv)[kArgVMax]) const override {
211    int i = 0;
212    argv[i++] = path_to_binary;
213    argv[i++] = "-iCfe";
214    argv[i++] = module_name_;
215    argv[i++] = nullptr;
216  }
217
218  bool ReachedEndOfOutput(const char *buffer, uptr length) const override;
219
220  bool ReadFromSymbolizer(char *buffer, uptr max_length) override {
221    if (!SymbolizerProcess::ReadFromSymbolizer(buffer, max_length))
222      return false;
223    // The returned buffer is empty when output is valid, but exceeds
224    // max_length.
225    if (*buffer == '\0')
226      return true;
227    // We should cut out output_terminator_ at the end of given buffer,
228    // appended by addr2line to mark the end of its meaningful output.
229    // We cannot scan buffer from it's beginning, because it is legal for it
230    // to start with output_terminator_ in case given offset is invalid. So,
231    // scanning from second character.
232    char *garbage = internal_strstr(buffer + 1, output_terminator_);
233    // This should never be NULL since buffer must end up with
234    // output_terminator_.
235    CHECK(garbage);
236    // Trim the buffer.
237    garbage[0] = '\0';
238    return true;
239  }
240
241  const char *module_name_;  // Owned, leaked.
242  static const char output_terminator_[];
243};
244
245const char Addr2LineProcess::output_terminator_[] = "??\n??:0\n";
246
247bool Addr2LineProcess::ReachedEndOfOutput(const char *buffer,
248                                          uptr length) const {
249  const size_t kTerminatorLen = sizeof(output_terminator_) - 1;
250  // Skip, if we read just kTerminatorLen bytes, because Addr2Line output
251  // should consist at least of two pairs of lines:
252  // 1. First one, corresponding to given offset to be symbolized
253  // (may be equal to output_terminator_, if offset is not valid).
254  // 2. Second one for output_terminator_, itself to mark the end of output.
255  if (length <= kTerminatorLen) return false;
256  // Addr2Line output should end up with output_terminator_.
257  return !internal_memcmp(buffer + length - kTerminatorLen,
258                          output_terminator_, kTerminatorLen);
259}
260
261class Addr2LinePool : public SymbolizerTool {
262 public:
263  explicit Addr2LinePool(const char *addr2line_path,
264                         LowLevelAllocator *allocator)
265      : addr2line_path_(addr2line_path), allocator_(allocator) {
266    addr2line_pool_.reserve(16);
267  }
268
269  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override {
270    if (const char *buf =
271            SendCommand(stack->info.module, stack->info.module_offset)) {
272      ParseSymbolizePCOutput(buf, stack);
273      return true;
274    }
275    return false;
276  }
277
278  bool SymbolizeData(uptr addr, DataInfo *info) override {
279    return false;
280  }
281
282 private:
283  const char *SendCommand(const char *module_name, uptr module_offset) {
284    Addr2LineProcess *addr2line = 0;
285    for (uptr i = 0; i < addr2line_pool_.size(); ++i) {
286      if (0 ==
287          internal_strcmp(module_name, addr2line_pool_[i]->module_name())) {
288        addr2line = addr2line_pool_[i];
289        break;
290      }
291    }
292    if (!addr2line) {
293      addr2line =
294          new(*allocator_) Addr2LineProcess(addr2line_path_, module_name);
295      addr2line_pool_.push_back(addr2line);
296    }
297    CHECK_EQ(0, internal_strcmp(module_name, addr2line->module_name()));
298    char buffer[kBufferSize];
299    internal_snprintf(buffer, kBufferSize, "0x%zx\n0x%zx\n",
300                      module_offset, dummy_address_);
301    return addr2line->SendCommand(buffer);
302  }
303
304  static const uptr kBufferSize = 64;
305  const char *addr2line_path_;
306  LowLevelAllocator *allocator_;
307  InternalMmapVector<Addr2LineProcess*> addr2line_pool_;
308  static const uptr dummy_address_ =
309      FIRST_32_SECOND_64(UINT32_MAX, UINT64_MAX);
310};
311
312#if SANITIZER_SUPPORTS_WEAK_HOOKS
313extern "C" {
314SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
315bool __sanitizer_symbolize_code(const char *ModuleName, u64 ModuleOffset,
316                                char *Buffer, int MaxLength);
317SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
318bool __sanitizer_symbolize_data(const char *ModuleName, u64 ModuleOffset,
319                                char *Buffer, int MaxLength);
320SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
321void __sanitizer_symbolize_flush();
322SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
323int __sanitizer_symbolize_demangle(const char *Name, char *Buffer,
324                                   int MaxLength);
325}  // extern "C"
326
327class InternalSymbolizer : public SymbolizerTool {
328 public:
329  static InternalSymbolizer *get(LowLevelAllocator *alloc) {
330    if (__sanitizer_symbolize_code != 0 &&
331        __sanitizer_symbolize_data != 0) {
332      return new(*alloc) InternalSymbolizer();
333    }
334    return 0;
335  }
336
337  bool SymbolizePC(uptr addr, SymbolizedStack *stack) override {
338    bool result = __sanitizer_symbolize_code(
339        stack->info.module, stack->info.module_offset, buffer_, kBufferSize);
340    if (result) ParseSymbolizePCOutput(buffer_, stack);
341    return result;
342  }
343
344  bool SymbolizeData(uptr addr, DataInfo *info) override {
345    bool result = __sanitizer_symbolize_data(info->module, info->module_offset,
346                                             buffer_, kBufferSize);
347    if (result) {
348      ParseSymbolizeDataOutput(buffer_, info);
349      info->start += (addr - info->module_offset);  // Add the base address.
350    }
351    return result;
352  }
353
354  void Flush() override {
355    if (__sanitizer_symbolize_flush)
356      __sanitizer_symbolize_flush();
357  }
358
359  const char *Demangle(const char *name) override {
360    if (__sanitizer_symbolize_demangle) {
361      for (uptr res_length = 1024;
362           res_length <= InternalSizeClassMap::kMaxSize;) {
363        char *res_buff = static_cast<char*>(InternalAlloc(res_length));
364        uptr req_length =
365            __sanitizer_symbolize_demangle(name, res_buff, res_length);
366        if (req_length > res_length) {
367          res_length = req_length + 1;
368          InternalFree(res_buff);
369          continue;
370        }
371        return res_buff;
372      }
373    }
374    return name;
375  }
376
377 private:
378  InternalSymbolizer() { }
379
380  static const int kBufferSize = 16 * 1024;
381  char buffer_[kBufferSize];
382};
383#else  // SANITIZER_SUPPORTS_WEAK_HOOKS
384
385class InternalSymbolizer : public SymbolizerTool {
386 public:
387  static InternalSymbolizer *get(LowLevelAllocator *alloc) { return 0; }
388};
389
390#endif  // SANITIZER_SUPPORTS_WEAK_HOOKS
391
392const char *Symbolizer::PlatformDemangle(const char *name) {
393  return DemangleSwiftAndCXX(name);
394}
395
396static SymbolizerTool *ChooseExternalSymbolizer(LowLevelAllocator *allocator) {
397  const char *path = common_flags()->external_symbolizer_path;
398  const char *binary_name = path ? StripModuleName(path) : "";
399  if (path && path[0] == '\0') {
400    VReport(2, "External symbolizer is explicitly disabled.\n");
401    return nullptr;
402  } else if (!internal_strcmp(binary_name, "llvm-symbolizer")) {
403    VReport(2, "Using llvm-symbolizer at user-specified path: %s\n", path);
404    return new(*allocator) LLVMSymbolizer(path, allocator);
405  } else if (!internal_strcmp(binary_name, "atos")) {
406#if SANITIZER_MAC
407    VReport(2, "Using atos at user-specified path: %s\n", path);
408    return new(*allocator) AtosSymbolizer(path, allocator);
409#else  // SANITIZER_MAC
410    Report("ERROR: Using `atos` is only supported on Darwin.\n");
411    Die();
412#endif  // SANITIZER_MAC
413  } else if (!internal_strcmp(binary_name, "addr2line")) {
414    VReport(2, "Using addr2line at user-specified path: %s\n", path);
415    return new(*allocator) Addr2LinePool(path, allocator);
416  } else if (path) {
417    Report("ERROR: External symbolizer path is set to '%s' which isn't "
418           "a known symbolizer. Please set the path to the llvm-symbolizer "
419           "binary or other known tool.\n", path);
420    Die();
421  }
422
423  // Otherwise symbolizer program is unknown, let's search $PATH
424  CHECK(path == nullptr);
425#if SANITIZER_MAC
426  if (const char *found_path = FindPathToBinary("atos")) {
427    VReport(2, "Using atos found at: %s\n", found_path);
428    return new(*allocator) AtosSymbolizer(found_path, allocator);
429  }
430#endif  // SANITIZER_MAC
431  if (const char *found_path = FindPathToBinary("llvm-symbolizer")) {
432    VReport(2, "Using llvm-symbolizer found at: %s\n", found_path);
433    return new(*allocator) LLVMSymbolizer(found_path, allocator);
434  }
435  if (common_flags()->allow_addr2line) {
436    if (const char *found_path = FindPathToBinary("addr2line")) {
437      VReport(2, "Using addr2line found at: %s\n", found_path);
438      return new(*allocator) Addr2LinePool(found_path, allocator);
439    }
440  }
441  return nullptr;
442}
443
444static void ChooseSymbolizerTools(IntrusiveList<SymbolizerTool> *list,
445                                  LowLevelAllocator *allocator) {
446  if (!common_flags()->symbolize) {
447    VReport(2, "Symbolizer is disabled.\n");
448    return;
449  }
450  if (IsAllocatorOutOfMemory()) {
451    VReport(2, "Cannot use internal symbolizer: out of memory\n");
452  } else if (SymbolizerTool *tool = InternalSymbolizer::get(allocator)) {
453    VReport(2, "Using internal symbolizer.\n");
454    list->push_back(tool);
455    return;
456  }
457  if (SymbolizerTool *tool = LibbacktraceSymbolizer::get(allocator)) {
458    VReport(2, "Using libbacktrace symbolizer.\n");
459    list->push_back(tool);
460    return;
461  }
462
463  if (SymbolizerTool *tool = ChooseExternalSymbolizer(allocator)) {
464    list->push_back(tool);
465  }
466
467#if SANITIZER_MAC
468  VReport(2, "Using dladdr symbolizer.\n");
469  list->push_back(new(*allocator) DlAddrSymbolizer());
470#endif  // SANITIZER_MAC
471}
472
473Symbolizer *Symbolizer::PlatformInit() {
474  IntrusiveList<SymbolizerTool> list;
475  list.clear();
476  ChooseSymbolizerTools(&list, &symbolizer_allocator_);
477  return new(symbolizer_allocator_) Symbolizer(list);
478}
479
480void Symbolizer::LateInitialize() {
481  Symbolizer::GetOrInit();
482  InitializeSwiftDemangler();
483}
484
485}  // namespace __sanitizer
486
487#endif  // SANITIZER_POSIX
488