sanitizer_procmaps_mac.cc revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0 
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
22namespace __sanitizer {
23
24MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
25  Reset();
26}
27
28MemoryMappingLayout::~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
45void 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
59void MemoryMappingLayout::CacheMemoryMappings() {
60  // No-op on Mac for now.
61}
62
63void 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.
74template<u32 kLCSegment, typename SegmentCommand>
75bool MemoryMappingLayout::NextSegmentLoad(
76    uptr *start, uptr *end, uptr *offset,
77    char filename[], uptr filename_size, uptr *protection) {
78  if (protection)
79    UNIMPLEMENTED();
80  const char* lc = current_load_cmd_addr_;
81  current_load_cmd_addr_ += ((const load_command *)lc)->cmdsize;
82  if (((const load_command *)lc)->cmd == kLCSegment) {
83    const sptr dlloff = _dyld_get_image_vmaddr_slide(current_image_);
84    const SegmentCommand* sc = (const SegmentCommand *)lc;
85    if (start) *start = sc->vmaddr + dlloff;
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
103bool 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
156uptr MemoryMappingLayout::DumpListOfModules(LoadedModule *modules,
157                                            uptr max_modules,
158                                            string_predicate_t filter) {
159  Reset();
160  uptr cur_beg, cur_end;
161  InternalScopedBuffer<char> module_name(kMaxPathLength);
162  uptr n_modules = 0;
163  for (uptr i = 0; n_modules < max_modules &&
164                       Next(&cur_beg, &cur_end, 0, module_name.data(),
165                            module_name.size(), 0);
166       i++) {
167    const char *cur_name = module_name.data();
168    if (cur_name[0] == '\0')
169      continue;
170    if (filter && !filter(cur_name))
171      continue;
172    LoadedModule *cur_module = 0;
173    if (n_modules > 0 &&
174        0 == internal_strcmp(cur_name, modules[n_modules - 1].full_name())) {
175      cur_module = &modules[n_modules - 1];
176    } else {
177      void *mem = &modules[n_modules];
178      cur_module = new(mem) LoadedModule(cur_name, cur_beg);
179      n_modules++;
180    }
181    cur_module->addAddressRange(cur_beg, cur_end);
182  }
183  return n_modules;
184}
185
186}  // namespace __sanitizer
187
188#endif  // SANITIZER_MAC
189