libsanitizer/sanitizer_common/sanitizer_symbolizer_mac.cpp

   1 //===-- sanitizer_symbolizer_mac.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 various sanitizers' runtime libraries.
  10 //
  11 // Implementation of Mac-specific "atos" symbolizer.
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "sanitizer_platform.h"
  15 #if SANITIZER_MAC
  16
  17 #include "sanitizer_allocator_internal.h"
  18 #include "sanitizer_mac.h"
  19 #include "sanitizer_symbolizer_mac.h"
  20
  21 #include <dlfcn.h>
  22 #include <errno.h>
  23 #include <mach/mach.h>
  24 #include <stdlib.h>
  25 #include <sys/wait.h>
  26 #include <unistd.h>
  27 #include <util.h>
  28
  29 namespace __sanitizer {
  30
  31 bool DlAddrSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
  32   Dl_info info;
  33   int result = dladdr((const void *)addr, &info);
  34   if (!result) return false;
  35
  36   // Compute offset if possible. `dladdr()` doesn't always ensure that `addr >=
  37   // sym_addr` so only compute the offset when this holds. Failure to find the
  38   // function offset is not treated as a failure because it might still be
  39   // possible to get the symbol name.
  40   uptr sym_addr = reinterpret_cast<uptr>(info.dli_saddr);
  41   if (addr >= sym_addr) {
  42     stack->info.function_offset = addr - sym_addr;
  43   }
  44
  45   const char *demangled = DemangleSwiftAndCXX(info.dli_sname);
  46   if (!demangled) return false;
  47   stack->info.function = internal_strdup(demangled);
  48   return true;
  49 }
  50
  51 bool DlAddrSymbolizer::SymbolizeData(uptr addr, DataInfo *datainfo) {
  52   Dl_info info;
  53   int result = dladdr((const void *)addr, &info);
  54   if (!result) return false;
  55   const char *demangled = DemangleSwiftAndCXX(info.dli_sname);
  56   datainfo->name = internal_strdup(demangled);
  57   datainfo->start = (uptr)info.dli_saddr;
  58   return true;
  59 }
  60
  61 #define K_ATOS_ENV_VAR "__check_mach_ports_lookup"
  62
  63 // This cannot live in `AtosSymbolizerProcess` because instances of that object
  64 // are allocated by the internal allocator which under ASan is poisoned with
  65 // kAsanInternalHeapMagic.
  66 static char kAtosMachPortEnvEntry[] = K_ATOS_ENV_VAR "=000000000000000";
  67
  68 class AtosSymbolizerProcess final : public SymbolizerProcess {
  69  public:
  70   explicit AtosSymbolizerProcess(const char *path)
  71       : SymbolizerProcess(path, /*use_posix_spawn*/ true) {
  72     pid_str_[0] = '\0';
  73   }
  74
  75   void LateInitialize() {
  76     if (SANITIZER_IOSSIM) {
  77       // `putenv()` may call malloc/realloc so it is only safe to do this
  78       // during LateInitialize() or later (i.e. we can't do this in the
  79       // constructor).  We also can't do this in `StartSymbolizerSubprocess()`
  80       // because in TSan we switch allocators when we're symbolizing.
  81       // We use `putenv()` rather than `setenv()` so that we can later directly
  82       // write into the storage without LibC getting involved to change what the
  83       // variable is set to
  84       int result = putenv(kAtosMachPortEnvEntry);
  85       CHECK_EQ(result, 0);
  86     }
  87   }
  88
  89  private:
  90   bool StartSymbolizerSubprocess() override {
  91     // Configure sandbox before starting atos process.
  92
  93     // Put the string command line argument in the object so that it outlives
  94     // the call to GetArgV.
  95     internal_snprintf(pid_str_, sizeof(pid_str_), "%d", internal_getpid());
  96
  97     if (SANITIZER_IOSSIM) {
  98       // `atos` in the simulator is restricted in its ability to retrieve the
  99       // task port for the target process (us) so we need to do extra work
 100       // to pass our task port to it.
 101       mach_port_t ports[]{mach_task_self()};
 102       kern_return_t ret =
 103           mach_ports_register(mach_task_self(), ports, /*count=*/1);
 104       CHECK_EQ(ret, KERN_SUCCESS);
 105
 106       // Set environment variable that signals to `atos` that it should look
 107       // for our task port. We can't call `setenv()` here because it might call
 108       // malloc/realloc. To avoid that we instead update the
 109       // `mach_port_env_var_entry_` variable with our current PID.
 110       uptr count = internal_snprintf(kAtosMachPortEnvEntry,
 111                                      sizeof(kAtosMachPortEnvEntry),
 112                                      K_ATOS_ENV_VAR "=%s", pid_str_);
 113       CHECK_GE(count, sizeof(K_ATOS_ENV_VAR) + internal_strlen(pid_str_));
 114       // Document our assumption but without calling `getenv()` in normal
 115       // builds.
 116       DCHECK(getenv(K_ATOS_ENV_VAR));
 117       DCHECK_EQ(internal_strcmp(getenv(K_ATOS_ENV_VAR), pid_str_), 0);
 118     }
 119
 120     return SymbolizerProcess::StartSymbolizerSubprocess();
 121   }
 122
 123   bool ReachedEndOfOutput(const char *buffer, uptr length) const override {
 124     return (length >= 1 && buffer[length - 1] == '\n');
 125   }
 126
 127   void GetArgV(const char *path_to_binary,
 128                const char *(&argv)[kArgVMax]) const override {
 129     int i = 0;
 130     argv[i++] = path_to_binary;
 131     argv[i++] = "-p";
 132     argv[i++] = &pid_str_[0];
 133     if (GetMacosAlignedVersion() == MacosVersion(10, 9)) {
 134       // On Mavericks atos prints a deprecation warning which we suppress by
 135       // passing -d. The warning isn't present on other OSX versions, even the
 136       // newer ones.
 137       argv[i++] = "-d";
 138     }
 139     argv[i++] = nullptr;
 140   }
 141
 142   char pid_str_[16];
 143   // Space for `\0` in `K_ATOS_ENV_VAR` is reused for `=`.
 144   static_assert(sizeof(kAtosMachPortEnvEntry) ==
 145                     (sizeof(K_ATOS_ENV_VAR) + sizeof(pid_str_)),
 146                 "sizes should match");
 147 };
 148
 149 #undef K_ATOS_ENV_VAR
 150
 151 static bool ParseCommandOutput(const char *str, uptr addr, char **out_name,
 152                                char **out_module, char **out_file, uptr *line,
 153                                uptr *start_address) {
 154   // Trim ending newlines.
 155   char *trim;
 156   ExtractTokenUpToDelimiter(str, "\n", &trim);
 157
 158   // The line from `atos` is in one of these formats:
 159   //   myfunction (in library.dylib) (sourcefile.c:17)
 160   //   myfunction (in library.dylib) + 0x1fe
 161   //   myfunction (in library.dylib) + 15
 162   //   0xdeadbeef (in library.dylib) + 0x1fe
 163   //   0xdeadbeef (in library.dylib) + 15
 164   //   0xdeadbeef (in library.dylib)
 165   //   0xdeadbeef
 166
 167   const char *rest = trim;
 168   char *symbol_name;
 169   rest = ExtractTokenUpToDelimiter(rest, " (in ", &symbol_name);
 170   if (rest[0] == '\0') {
 171     InternalFree(symbol_name);
 172     InternalFree(trim);
 173     return false;
 174   }
 175
 176   if (internal_strncmp(symbol_name, "0x", 2) != 0)
 177     *out_name = symbol_name;
 178   else
 179     InternalFree(symbol_name);
 180   rest = ExtractTokenUpToDelimiter(rest, ") ", out_module);
 181
 182   if (rest[0] == '(') {
 183     if (out_file) {
 184       rest++;
 185       rest = ExtractTokenUpToDelimiter(rest, ":", out_file);
 186       char *extracted_line_number;
 187       rest = ExtractTokenUpToDelimiter(rest, ")", &extracted_line_number);
 188       if (line) *line = (uptr)internal_atoll(extracted_line_number);
 189       InternalFree(extracted_line_number);
 190     }
 191   } else if (rest[0] == '+') {
 192     rest += 2;
 193     uptr offset = internal_atoll(rest);
 194     if (start_address) *start_address = addr - offset;
 195   }
 196
 197   InternalFree(trim);
 198   return true;
 199 }
 200
 201 AtosSymbolizer::AtosSymbolizer(const char *path, LowLevelAllocator *allocator)
 202     : process_(new (*allocator) AtosSymbolizerProcess(path)) {}
 203
 204 bool AtosSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
 205   if (!process_) return false;
 206   if (addr == 0) return false;
 207   char command[32];
 208   internal_snprintf(command, sizeof(command), "0x%zx\n", addr);
 209   const char *buf = process_->SendCommand(command);
 210   if (!buf) return false;
 211   uptr line;
 212   uptr start_address = AddressInfo::kUnknown;
 213   if (!ParseCommandOutput(buf, addr, &stack->info.function, &stack->info.module,
 214                           &stack->info.file, &line, &start_address)) {
 215     process_ = nullptr;
 216     return false;
 217   }
 218   stack->info.line = (int)line;
 219
 220   if (start_address == AddressInfo::kUnknown) {
 221     // Fallback to dladdr() to get function start address if atos doesn't report
 222     // it.
 223     Dl_info info;
 224     int result = dladdr((const void *)addr, &info);
 225     if (result)
 226       start_address = reinterpret_cast<uptr>(info.dli_saddr);
 227   }
 228
 229   // Only assign to `function_offset` if we were able to get the function's
 230   // start address and we got a sensible `start_address` (dladdr doesn't always
 231   // ensure that `addr >= sym_addr`).
 232   if (start_address != AddressInfo::kUnknown && addr >= start_address) {
 233     stack->info.function_offset = addr - start_address;
 234   }
 235   return true;
 236 }
 237
 238 bool AtosSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
 239   if (!process_) return false;
 240   char command[32];
 241   internal_snprintf(command, sizeof(command), "0x%zx\n", addr);
 242   const char *buf = process_->SendCommand(command);
 243   if (!buf) return false;
 244   if (!ParseCommandOutput(buf, addr, &info->name, &info->module, nullptr,
 245                           nullptr, &info->start)) {
 246     process_ = nullptr;
 247     return false;
 248   }
 249   return true;
 250 }
 251
 252 void AtosSymbolizer::LateInitialize() { process_->LateInitialize(); }
 253
 254 }  // namespace __sanitizer
 255
 256 #endif  // SANITIZER_MAC