lib/sanitizer_common/sanitizer_procmaps_mac.cc

   1 //===-- sanitizer_procmaps_mac.cc -----------------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Information about the process mappings (Mac-specific parts).
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "sanitizer_platform.h"
  14 #if SANITIZER_MAC
  15 #include "sanitizer_common.h"
  16 #include "sanitizer_placement_new.h"
  17 #include "sanitizer_procmaps.h"
  18
  19 #include <mach-o/dyld.h>
  20 #include <mach-o/loader.h>
  21
  22 namespace __sanitizer {
  23
  24 MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
  25   Reset();
  26 }
  27
  28 MemoryMappingLayout::~MemoryMappingLayout() {
  29 }
  30
  31 // More information about Mach-O headers can be found in mach-o/loader.h
  32 // Each Mach-O image has a header (mach_header or mach_header_64) starting with
  33 // a magic number, and a list of linker load commands directly following the
  34 // header.
  35 // A load command is at least two 32-bit words: the command type and the
  36 // command size in bytes. We're interested only in segment load commands
  37 // (LC_SEGMENT and LC_SEGMENT_64), which tell that a part of the file is mapped
  38 // into the task's address space.
  39 // The |vmaddr|, |vmsize| and |fileoff| fields of segment_command or
  40 // segment_command_64 correspond to the memory address, memory size and the
  41 // file offset of the current memory segment.
  42 // Because these fields are taken from the images as is, one needs to add
  43 // _dyld_get_image_vmaddr_slide() to get the actual addresses at runtime.
  44
  45 void MemoryMappingLayout::Reset() {
  46   // Count down from the top.
  47   // TODO(glider): as per man 3 dyld, iterating over the headers with
  48   // _dyld_image_count is thread-unsafe. We need to register callbacks for
  49   // adding and removing images which will invalidate the MemoryMappingLayout
  50   // state.
  51   current_image_ = _dyld_image_count();
  52   current_load_cmd_count_ = -1;
  53   current_load_cmd_addr_ = 0;
  54   current_magic_ = 0;
  55   current_filetype_ = 0;
  56 }
  57
  58 // static
  59 void MemoryMappingLayout::CacheMemoryMappings() {
  60   // No-op on Mac for now.
  61 }
  62
  63 void MemoryMappingLayout::LoadFromCache() {
  64   // No-op on Mac for now.
  65 }
  66
  67 // Next and NextSegmentLoad were inspired by base/sysinfo.cc in
  68 // Google Perftools, http://code.google.com/p/google-perftools.
  69
  70 // NextSegmentLoad scans the current image for the next segment load command
  71 // and returns the start and end addresses and file offset of the corresponding
  72 // segment.
  73 // Note that the segment addresses are not necessarily sorted.
  74 template<u32 kLCSegment, typename SegmentCommand>
  75 bool MemoryMappingLayout::NextSegmentLoad(
  76     uptr *start, uptr *end, uptr *offset,
  77     char filename[], uptr filename_size, uptr *protection) {
  78   const char* lc = current_load_cmd_addr_;
  79   current_load_cmd_addr_ += ((const load_command *)lc)->cmdsize;
  80   if (((const load_command *)lc)->cmd == kLCSegment) {
  81     const sptr dlloff = _dyld_get_image_vmaddr_slide(current_image_);
  82     const SegmentCommand* sc = (const SegmentCommand *)lc;
  83     if (start) *start = sc->vmaddr + dlloff;
  84     if (protection) {
  85       // Return the initial protection.
  86       *protection = sc->initprot;
  87     }
  88     if (end) *end = sc->vmaddr + sc->vmsize + dlloff;
  89     if (offset) {
  90       if (current_filetype_ == /*MH_EXECUTE*/ 0x2) {
  91         *offset = sc->vmaddr;
  92       } else {
  93         *offset = sc->fileoff;
  94       }
  95     }
  96     if (filename) {
  97       internal_strncpy(filename, _dyld_get_image_name(current_image_),
  98                        filename_size);
  99     }
 100     return true;
 101   }
 102   return false;
 103 }
 104
 105 bool MemoryMappingLayout::Next(uptr *start, uptr *end, uptr *offset,
 106                                char filename[], uptr filename_size,
 107                                uptr *protection) {
 108   for (; current_image_ >= 0; current_image_--) {
 109     const mach_header* hdr = _dyld_get_image_header(current_image_);
 110     if (!hdr) continue;
 111     if (current_load_cmd_count_ < 0) {
 112       // Set up for this image;
 113       current_load_cmd_count_ = hdr->ncmds;
 114       current_magic_ = hdr->magic;
 115       current_filetype_ = hdr->filetype;
 116       switch (current_magic_) {
 117 #ifdef MH_MAGIC_64
 118         case MH_MAGIC_64: {
 119           current_load_cmd_addr_ = (char*)hdr + sizeof(mach_header_64);
 120           break;
 121         }
 122 #endif
 123         case MH_MAGIC: {
 124           current_load_cmd_addr_ = (char*)hdr + sizeof(mach_header);
 125           break;
 126         }
 127         default: {
 128           continue;
 129         }
 130       }
 131     }
 132
 133     for (; current_load_cmd_count_ >= 0; current_load_cmd_count_--) {
 134       switch (current_magic_) {
 135         // current_magic_ may be only one of MH_MAGIC, MH_MAGIC_64.
 136 #ifdef MH_MAGIC_64
 137         case MH_MAGIC_64: {
 138           if (NextSegmentLoad<LC_SEGMENT_64, struct segment_command_64>(
 139                   start, end, offset, filename, filename_size, protection))
 140             return true;
 141           break;
 142         }
 143 #endif
 144         case MH_MAGIC: {
 145           if (NextSegmentLoad<LC_SEGMENT, struct segment_command>(
 146                   start, end, offset, filename, filename_size, protection))
 147             return true;
 148           break;
 149         }
 150       }
 151     }
 152     // If we get here, no more load_cmd's in this image talk about
 153     // segments.  Go on to the next image.
 154   }
 155   return false;
 156 }
 157
 158 uptr MemoryMappingLayout::DumpListOfModules(LoadedModule *modules,
 159                                             uptr max_modules,
 160                                             string_predicate_t filter) {
 161   Reset();
 162   uptr cur_beg, cur_end, prot;
 163   InternalScopedBuffer<char> module_name(kMaxPathLength);
 164   uptr n_modules = 0;
 165   for (uptr i = 0; n_modules < max_modules &&
 166                        Next(&cur_beg, &cur_end, 0, module_name.data(),
 167                             module_name.size(), &prot);
 168        i++) {
 169     const char *cur_name = module_name.data();
 170     if (cur_name[0] == '\0')
 171       continue;
 172     if (filter && !filter(cur_name))
 173       continue;
 174     LoadedModule *cur_module = 0;
 175     if (n_modules > 0 &&
 176         0 == internal_strcmp(cur_name, modules[n_modules - 1].full_name())) {
 177       cur_module = &modules[n_modules - 1];
 178     } else {
 179       void *mem = &modules[n_modules];
 180       cur_module = new(mem) LoadedModule(cur_name, cur_beg);
 181       n_modules++;
 182     }
 183     cur_module->addAddressRange(cur_beg, cur_end, prot & kProtectionExecute);
 184   }
 185   return n_modules;
 186 }
 187
 188 }  // namespace __sanitizer
 189
 190 #endif  // SANITIZER_MAC