compiler-rt/lib/sanitizer_common/sanitizer_mac.cc

//===-- sanitizer_mac.cc --------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is shared between AddressSanitizer and ThreadSanitizer
// run-time libraries and implements mac-specific functions from
// sanitizer_libc.h.
//===----------------------------------------------------------------------===//

#ifdef __APPLE__

#include "sanitizer_internal_defs.h"
#include "sanitizer_libc.h"
#include "sanitizer_procmaps.h"

#include <mach-o/dyld.h>
#include <mach-o/loader.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>

namespace __sanitizer {

void *internal_mmap(void *addr, size_t length, int prot, int flags,
                    int fd, u64 offset) {
  return mmap(addr, length, prot, flags, fd, offset);
}

int internal_munmap(void *addr, uptr length) {
  return munmap(addr, length);
}

int internal_close(fd_t fd) {
  return close(fd);
}

fd_t internal_open(const char *filename, bool write) {
  return open(filename,
              write ? O_WRONLY | O_CREAT : O_RDONLY, 0660);
}

uptr internal_read(fd_t fd, void *buf, uptr count) {
  return read(fd, buf, count);
}

uptr internal_write(fd_t fd, const void *buf, uptr count) {
  return write(fd, buf, count);
}

uptr internal_filesize(fd_t fd) {
  struct stat st = {};
  if (fstat(fd, &st))
    return -1;
  return (uptr)st.st_size;
}

int internal_dup2(int oldfd, int newfd) {
  return dup2(oldfd, newfd);
}

// ----------------- ProcessMaps implementation.

ProcessMaps::ProcessMaps() {
  Reset();
}

ProcessMaps::~ProcessMaps() {
}

// More information about Mach-O headers can be found in mach-o/loader.h
// Each Mach-O image has a header (mach_header or mach_header_64) starting with
// a magic number, and a list of linker load commands directly following the
// header.
// A load command is at least two 32-bit words: the command type and the
// command size in bytes. We're interested only in segment load commands
// (LC_SEGMENT and LC_SEGMENT_64), which tell that a part of the file is mapped
// into the task's address space.
// The |vmaddr|, |vmsize| and |fileoff| fields of segment_command or
// segment_command_64 correspond to the memory address, memory size and the
// file offset of the current memory segment.
// Because these fields are taken from the images as is, one needs to add
// _dyld_get_image_vmaddr_slide() to get the actual addresses at runtime.

void ProcessMaps::Reset() {
  // Count down from the top.
  // TODO(glider): as per man 3 dyld, iterating over the headers with
  // _dyld_image_count is thread-unsafe. We need to register callbacks for
  // adding and removing images which will invalidate the ProcessMaps state.
  current_image_ = _dyld_image_count();
  current_load_cmd_count_ = -1;
  current_load_cmd_addr_ = 0;
  current_magic_ = 0;
}

// Next and NextSegmentLoad were inspired by base/sysinfo.cc in
// Google Perftools, http://code.google.com/p/google-perftools.

// NextSegmentLoad scans the current image for the next segment load command
// and returns the start and end addresses and file offset of the corresponding
// segment.
// Note that the segment addresses are not necessarily sorted.
template<u32 kLCSegment, typename SegmentCommand>
bool ProcessMaps::NextSegmentLoad(
    uptr *start, uptr *end, uptr *offset,
    char filename[], uptr filename_size) {
  const char* lc = current_load_cmd_addr_;
  current_load_cmd_addr_ += ((const load_command *)lc)->cmdsize;
  if (((const load_command *)lc)->cmd == kLCSegment) {
    const sptr dlloff = _dyld_get_image_vmaddr_slide(current_image_);
    const SegmentCommand* sc = (const SegmentCommand *)lc;
    if (start) *start = sc->vmaddr + dlloff;
    if (end) *end = sc->vmaddr + sc->vmsize + dlloff;
    if (offset) *offset = sc->fileoff;
    if (filename) {
      internal_strncpy(filename, _dyld_get_image_name(current_image_),
                       filename_size);
    }
    return true;
  }
  return false;
}

bool ProcessMaps::Next(uptr *start, uptr *end, uptr *offset,
                       char filename[], uptr filename_size) {
  for (; current_image_ >= 0; current_image_--) {
    const mach_header* hdr = _dyld_get_image_header(current_image_);
    if (!hdr) continue;
    if (current_load_cmd_count_ < 0) {
      // Set up for this image;
      current_load_cmd_count_ = hdr->ncmds;
      current_magic_ = hdr->magic;
      switch (current_magic_) {
#ifdef MH_MAGIC_64
        case MH_MAGIC_64: {
          current_load_cmd_addr_ = (char*)hdr + sizeof(mach_header_64);
          break;
        }
#endif
        case MH_MAGIC: {
          current_load_cmd_addr_ = (char*)hdr + sizeof(mach_header);
          break;
        }
        default: {
          continue;
        }
      }
    }

    for (; current_load_cmd_count_ >= 0; current_load_cmd_count_--) {
      switch (current_magic_) {
        // current_magic_ may be only one of MH_MAGIC, MH_MAGIC_64.
#ifdef MH_MAGIC_64
        case MH_MAGIC_64: {
          if (NextSegmentLoad<LC_SEGMENT_64, struct segment_command_64>(
                  start, end, offset, filename, filename_size))
            return true;
          break;
        }
#endif
        case MH_MAGIC: {
          if (NextSegmentLoad<LC_SEGMENT, struct segment_command>(
                  start, end, offset, filename, filename_size))
            return true;
          break;
        }
      }
    }
    // If we get here, no more load_cmd's in this image talk about
    // segments.  Go on to the next image.
  }
  return false;
}

bool ProcessMaps::GetObjectNameAndOffset(uptr addr, uptr *offset,
                                         char filename[],
                                         uptr filename_size) {
  return IterateForObjectNameAndOffset(addr, offset, filename, filename_size);
}

}  // namespace __sanitizer

#endif  // __APPLE__