libsanitizer/sanitizer_common/sanitizer_procmaps_mac.cc

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