sanitizer_procmaps_mac.cc revision 5d71de26cedae3dafc17449fe0182045c0bd20e8 
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  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
105bool 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
158uptr 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
191