tor-browser

shared-libraries-macos.cc (6723B)

---

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/SharedLibraries.h"

#include "platform.h"

#include <AvailabilityMacros.h>

#include <dlfcn.h>
#include <mach-o/arch.h>
#include <mach-o/dyld_images.h>
#include <mach-o/dyld.h>
#include <mach-o/loader.h>
#include <mach/mach_init.h>
#include <mach/mach_traps.h>
#include <mach/task_info.h>
#include <mach/task.h>
#include <sstream>
#include <string.h>
#include <vector>

// Architecture specific abstraction.
#if defined(GP_ARCH_x86)
typedef mach_header platform_mach_header;
typedef segment_command mach_segment_command_type;
#  define MACHO_MAGIC_NUMBER MH_MAGIC
#  define CMD_SEGMENT LC_SEGMENT
#  define seg_size uint32_t
#else
typedef mach_header_64 platform_mach_header;
typedef segment_command_64 mach_segment_command_type;
#  define MACHO_MAGIC_NUMBER MH_MAGIC_64
#  define CMD_SEGMENT LC_SEGMENT_64
#  define seg_size uint64_t
#endif

struct NativeSharedLibrary {
 const platform_mach_header* header;
 std::string path;
};
static std::vector<NativeSharedLibrary>* sSharedLibrariesList = nullptr;

class MOZ_RAII SharedLibrariesLock {
public:
 SharedLibrariesLock() { sSharedLibrariesMutex.Lock(); }

 ~SharedLibrariesLock() { sSharedLibrariesMutex.Unlock(); }

 SharedLibrariesLock(const SharedLibrariesLock&) = delete;
 void operator=(const SharedLibrariesLock&) = delete;

private:
 static mozilla::baseprofiler::detail::BaseProfilerMutex sSharedLibrariesMutex;
};

MOZ_RUNINIT mozilla::baseprofiler::detail::BaseProfilerMutex
   SharedLibrariesLock::sSharedLibrariesMutex;

static void SharedLibraryAddImage(const struct mach_header* mh,
                                 intptr_t vmaddr_slide) {
 // NOTE: Presumably for backwards-compatibility reasons, this function accepts
 // a mach_header even on 64-bit where it ought to be a mach_header_64. We cast
 // it to the right type here.
 auto header = reinterpret_cast<const platform_mach_header*>(mh);

 Dl_info info;
 if (!dladdr(header, &info)) {
   return;
 }

 SharedLibrariesLock lock;
 if (!sSharedLibrariesList) {
   return;
 }

 NativeSharedLibrary lib = {header, info.dli_fname};
 sSharedLibrariesList->push_back(lib);
}

static void SharedLibraryRemoveImage(const struct mach_header* mh,
                                    intptr_t vmaddr_slide) {
 // NOTE: Presumably for backwards-compatibility reasons, this function accepts
 // a mach_header even on 64-bit where it ought to be a mach_header_64. We cast
 // it to the right type here.
 auto header = reinterpret_cast<const platform_mach_header*>(mh);

 SharedLibrariesLock lock;
 if (!sSharedLibrariesList) {
   return;
 }

 uint32_t count = sSharedLibrariesList->size();
 for (uint32_t i = 0; i < count; ++i) {
   if ((*sSharedLibrariesList)[i].header == header) {
     sSharedLibrariesList->erase(sSharedLibrariesList->begin() + i);
     return;
   }
 }
}

void SharedLibraryInfo::Initialize() {
 // NOTE: We intentionally leak this memory here. We're allocating dynamically
 // in order to avoid static initializers.
 sSharedLibrariesList = new std::vector<NativeSharedLibrary>();

 _dyld_register_func_for_add_image(SharedLibraryAddImage);
 _dyld_register_func_for_remove_image(SharedLibraryRemoveImage);
}

static void addSharedLibrary(const platform_mach_header* header,
                            const char* path, SharedLibraryInfo& info) {
 const struct load_command* cmd =
     reinterpret_cast<const struct load_command*>(header + 1);

 seg_size size = 0;
 unsigned long long start = reinterpret_cast<unsigned long long>(header);
 // Find the cmd segment in the macho image. It will contain the offset we care
 // about.
 const uint8_t* uuid_bytes = nullptr;
 for (unsigned int i = 0;
      cmd && (i < header->ncmds) && (uuid_bytes == nullptr || size == 0);
      ++i) {
   if (cmd->cmd == CMD_SEGMENT) {
     const mach_segment_command_type* seg =
         reinterpret_cast<const mach_segment_command_type*>(cmd);

     if (!strcmp(seg->segname, "__TEXT")) {
       size = seg->vmsize;
     }
   } else if (cmd->cmd == LC_UUID) {
     const uuid_command* ucmd = reinterpret_cast<const uuid_command*>(cmd);
     uuid_bytes = ucmd->uuid;
   }

   cmd = reinterpret_cast<const struct load_command*>(
       reinterpret_cast<const char*>(cmd) + cmd->cmdsize);
 }

 std::string uuid;
 std::string breakpadId;
 if (uuid_bytes != nullptr) {
   static constexpr char digits[16] = {'0', '1', '2', '3', '4', '5', '6', '7',
                                       '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
   for (int i = 0; i < 16; ++i) {
     uint8_t byte = uuid_bytes[i];
     uuid += digits[byte >> 4];
     uuid += digits[byte & 0xFu];
   }

   // Breakpad id is the same as the uuid but with the additional trailing 0
   // for the breakpad id age.
   breakpadId = uuid;
   // breakpad id age.
   breakpadId += '0';
 }

 std::string pathStr = path;

 size_t pos = pathStr.rfind('/');
 std::string nameStr =
     (pos != std::string::npos) ? pathStr.substr(pos + 1) : pathStr;

 const NXArchInfo* archInfo =
     NXGetArchInfoFromCpuType(header->cputype, header->cpusubtype);

 info.AddSharedLibrary(SharedLibrary(
     start, start + size, 0, breakpadId, uuid, nameStr, pathStr, nameStr,
     pathStr, std::string{}, archInfo ? archInfo->name : ""));
}

// Translate the statically stored sSharedLibrariesList information into a
// SharedLibraryInfo object.
SharedLibraryInfo SharedLibraryInfo::GetInfoForSelf() {
 SharedLibrariesLock lock;
 SharedLibraryInfo sharedLibraryInfo;

 for (auto& info : *sSharedLibrariesList) {
   addSharedLibrary(info.header, info.path.c_str(), sharedLibraryInfo);
 }

 // Add the entry for dyld itself.
 // We only support macOS 10.12+, which corresponds to dyld version 15+.
 // dyld version 15 added the dyldPath property.
 task_dyld_info_data_t task_dyld_info;
 mach_msg_type_number_t count = TASK_DYLD_INFO_COUNT;
 if (task_info(mach_task_self(), TASK_DYLD_INFO, (task_info_t)&task_dyld_info,
               &count) != KERN_SUCCESS) {
   return sharedLibraryInfo;
 }

 struct dyld_all_image_infos* aii =
     (struct dyld_all_image_infos*)task_dyld_info.all_image_info_addr;
 if (aii->version >= 15) {
   const platform_mach_header* header =
       reinterpret_cast<const platform_mach_header*>(
           aii->dyldImageLoadAddress);
   addSharedLibrary(header, aii->dyldPath, sharedLibraryInfo);
 }

 return sharedLibraryInfo;
}