text: //===-- sanitizer_symbolizer_mac.cpp --------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // This file is shared between various sanitizers' runtime libraries.
  //
  // Implementation of Mac-specific "atos" symbolizer.
  //===----------------------------------------------------------------------===//
  
  #include "sanitizer_platform.h"
  #if SANITIZER_MAC
  
  #include "sanitizer_allocator_internal.h"
  #include "sanitizer_mac.h"
  #include "sanitizer_symbolizer_mac.h"
  
  #include <dlfcn.h>
  #include <errno.h>
  #include <mach/mach.h>
  #include <stdlib.h>
  #include <sys/wait.h>
  #include <unistd.h>
  #include <util.h>
  
  namespace __sanitizer {
  
  bool DlAddrSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
    Dl_info info;
    int result = dladdr((const void *)addr, &info);
    if (!result) return false;
  
    CHECK(addr >= reinterpret_cast<uptr>(info.dli_saddr));
    stack->info.function_offset = addr - reinterpret_cast<uptr>(info.dli_saddr);
    const char *demangled = DemangleSwiftAndCXX(info.dli_sname);
    if (!demangled) return false;
    stack->info.function = internal_strdup(demangled);
    return true;
  }
  
  bool DlAddrSymbolizer::SymbolizeData(uptr addr, DataInfo *datainfo) {
    Dl_info info;
    int result = dladdr((const void *)addr, &info);
    if (!result) return false;
    const char *demangled = DemangleSwiftAndCXX(info.dli_sname);
    datainfo->name = internal_strdup(demangled);
    datainfo->start = (uptr)info.dli_saddr;
    return true;
  }
  
  #define K_ATOS_ENV_VAR "__check_mach_ports_lookup"
  
  // This cannot live in `AtosSymbolizerProcess` because instances of that object
  // are allocated by the internal allocator which under ASan is poisoned with
  // kAsanInternalHeapMagic.
  static char kAtosMachPortEnvEntry[] = K_ATOS_ENV_VAR "=000000000000000";
  
  class AtosSymbolizerProcess : public SymbolizerProcess {
   public:
    explicit AtosSymbolizerProcess(const char *path)
        : SymbolizerProcess(path, /*use_posix_spawn*/ true) {
      pid_str_[0] = '\0';
    }
  
    void LateInitialize() {
      if (SANITIZER_IOSSIM) {
        // `putenv()` may call malloc/realloc so it is only safe to do this
        // during LateInitialize() or later (i.e. we can't do this in the
        // constructor).  We also can't do this in `StartSymbolizerSubprocess()`
        // because in TSan we switch allocators when we're symbolizing.
        // We use `putenv()` rather than `setenv()` so that we can later directly
        // write into the storage without LibC getting involved to change what the
        // variable is set to
        int result = putenv(kAtosMachPortEnvEntry);
        CHECK_EQ(result, 0);
      }
    }
  
   private:
    bool StartSymbolizerSubprocess() override {
      // Configure sandbox before starting atos process.
  
      // 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", internal_getpid());
  
      if (SANITIZER_IOSSIM) {
        // `atos` in the simulator is restricted in its ability to retrieve the
        // task port for the target process (us) so we need to do extra work
        // to pass our task port to it.
        mach_port_t ports[]{mach_task_self()};
        kern_return_t ret =
            mach_ports_register(mach_task_self(), ports, /*count=*/1);
        CHECK_EQ(ret, KERN_SUCCESS);
  
        // Set environment variable that signals to `atos` that it should look
        // for our task port. We can't call `setenv()` here because it might call
        // malloc/realloc. To avoid that we instead update the
        // `mach_port_env_var_entry_` variable with our current PID.
        uptr count = internal_snprintf(kAtosMachPortEnvEntry,
                                       sizeof(kAtosMachPortEnvEntry),
                                       K_ATOS_ENV_VAR "=%s", pid_str_);
        CHECK_GE(count, sizeof(K_ATOS_ENV_VAR) + internal_strlen(pid_str_));
        // Document our assumption but without calling `getenv()` in normal
        // builds.
        DCHECK(getenv(K_ATOS_ENV_VAR));
        DCHECK_EQ(internal_strcmp(getenv(K_ATOS_ENV_VAR), pid_str_), 0);
      }
  
      return SymbolizerProcess::StartSymbolizerSubprocess();
    }
  
    bool ReachedEndOfOutput(const char *buffer, usize length) const override {
      return (length >= 1 && buffer[length - 1] == '\n');
    }
  
    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 (GetMacosAlignedVersion() == MacosVersion(10, 9)) {
        // 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.
        argv[i++] = "-d";
      }
      argv[i++] = nullptr;
    }
  
    char pid_str_[16];
    // Space for `\0` in `K_ATOS_ENV_VAR` is reused for `=`.
    static_assert(sizeof(kAtosMachPortEnvEntry) ==
                      (sizeof(K_ATOS_ENV_VAR) + sizeof(pid_str_)),
                  "sizes should match");
  };
  
  #undef K_ATOS_ENV_VAR
  
  static bool ParseCommandOutput(const char *str, uptr addr, char **out_name,
                                 char **out_module, char **out_file, usize *line,
                                 uptr *start_address) {
    // Trim ending newlines.
    char *trim;
    ExtractTokenUpToDelimiter(str, "\n", &trim);
  
    // The line from `atos` is in one of these formats:
    //   myfunction (in library.dylib) (sourcefile.c:17)
    //   myfunction (in library.dylib) + 0x1fe
    //   myfunction (in library.dylib) + 15
    //   0xdeadbeef (in library.dylib) + 0x1fe
    //   0xdeadbeef (in library.dylib) + 15
    //   0xdeadbeef (in library.dylib)
    //   0xdeadbeef
  
    const char *rest = trim;
    char *symbol_name;
    rest = ExtractTokenUpToDelimiter(rest, " (in ", &symbol_name);
    if (rest[0] == '\0') {
      InternalFree(symbol_name);
      InternalFree(trim);
      return false;
    }
  
    if (internal_strncmp(symbol_name, "0x", 2) != 0)
      *out_name = symbol_name;
    else
      InternalFree(symbol_name);
    rest = ExtractTokenUpToDelimiter(rest, ") ", out_module);
  
    if (rest[0] == '(') {
      if (out_file) {
        rest++;
        rest = ExtractTokenUpToDelimiter(rest, ":", out_file);
        char *extracted_line_number;
        rest = ExtractTokenUpToDelimiter(rest, ")", &extracted_line_number);
        if (line) *line = (usize)internal_atoll(extracted_line_number);
        InternalFree(extracted_line_number);
      }
    } else if (rest[0] == '+') {
      rest += 2;
      usize offset = internal_atoll(rest);
      if (start_address) *start_address = addr - offset;
    }
  
    InternalFree(trim);
    return true;
  }
  
  AtosSymbolizer::AtosSymbolizer(const char *path, LowLevelAllocator *allocator)
      : process_(new (*allocator) AtosSymbolizerProcess(path)) {}
  
  bool AtosSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
    if (!process_) return false;
    if (addr == 0) return false;
    char command[32];
    internal_snprintf(command, sizeof(command), "0x%zx\n", addr);
    const char *buf = process_->SendCommand(command);
    if (!buf) return false;
    usize line;
    uptr start_address = AddressInfo::kUnknown;
    if (!ParseCommandOutput(buf, addr, &stack->info.function, &stack->info.module,
                            &stack->info.file, &line, &start_address)) {
      process_ = nullptr;
      return false;
    }
    stack->info.line = (int)line;
  
    if (start_address == AddressInfo::kUnknown) {
      // Fallback to dladdr() to get function start address if atos doesn't report
      // it.
      Dl_info info;
      int result = dladdr((const void *)addr, &info);
      if (result)
        start_address = reinterpret_cast<uptr>(info.dli_saddr);
    }
  
    // Only assig to `function_offset` if we were able to get the function's
    // start address.
    if (start_address != AddressInfo::kUnknown) {
      CHECK(addr >= start_address);
      stack->info.function_offset = addr - start_address;
    }
    return true;
  }
  
  bool AtosSymbolizer::SymbolizeData(uptr addr, DataInfo *info) {
    if (!process_) return false;
    char command[32];
    internal_snprintf(command, sizeof(command), "0x%zx\n", addr);
    const char *buf = process_->SendCommand(command);
    if (!buf) return false;
    if (!ParseCommandOutput(buf, addr, &info->name, &info->module, nullptr,
                            nullptr, &info->start)) {
      process_ = nullptr;
      return false;
    }
    return true;
  }
  
  void AtosSymbolizer::LateInitialize() { process_->LateInitialize(); }
  
  }  // namespace __sanitizer
  
  #endif  // SANITIZER_MAC
  