src/malloc_hook_mmap_freebsd.h

// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2011, Google Inc.
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// Override mmap/munmap/mremap/sbrk to provide support for calling the
// related hooks (in addition, of course, to doing what these
// functions normally do).

#ifndef __FreeBSD__
# error Should only be including malloc_hook_mmap_freebsd.h on FreeBSD systems.
#endif

#include <unistd.h>
#include <sys/syscall.h>
#include <sys/mman.h>
#include <errno.h>
#include <dlfcn.h>

// Make sure mmap doesn't get #define'd away by <sys/mman.h>
#undef mmap

// According to the FreeBSD documentation, use syscall if you do not
// need 64-bit alignment otherwise use __syscall. Indeed, syscall
// doesn't work correctly in most situations on 64-bit. It's return
// type is 'int' so for things like SYS_mmap, it actually truncates
// the returned address to 32-bits.
#if defined(__amd64__) || defined(__x86_64__)
# define MALLOC_HOOK_SYSCALL __syscall
#else
# define MALLOC_HOOK_SYSCALL syscall
#endif


extern "C" {
  void* mmap(void *start, size_t length,int prot, int flags,
             int fd, off_t offset) __THROW
    ATTRIBUTE_SECTION(malloc_hook);
  int munmap(void* start, size_t length) __THROW
    ATTRIBUTE_SECTION(malloc_hook);
  void* sbrk(intptr_t increment) __THROW
    ATTRIBUTE_SECTION(malloc_hook);
}

static inline void* do_mmap(void *start, size_t length,
                            int prot, int flags,
                            int fd, off_t offset) __THROW {
  return (void *)MALLOC_HOOK_SYSCALL(SYS_mmap,
                                     start, length, prot, flags, fd, offset);
}

static inline void* do_sbrk(intptr_t increment) {
  static void *(*libc_sbrk)(intptr_t);
  if (libc_sbrk == NULL)
    libc_sbrk = (void *(*)(intptr_t))dlsym(RTLD_NEXT, "sbrk");

  return libc_sbrk(increment);
}


extern "C" void* mmap(void *start, size_t length, int prot, int flags,
                      int fd, off_t offset) __THROW {
  MallocHook::InvokePreMmapHook(start, length, prot, flags, fd, offset);
  void *result;
  if (!MallocHook::InvokeMmapReplacement(
          start, length, prot, flags, fd, offset, &result)) {
    result = do_mmap(start, length, prot, flags, fd,
                       static_cast<size_t>(offset)); // avoid sign extension
  }
  MallocHook::InvokeMmapHook(result, start, length, prot, flags, fd, offset);
  return result;
}

extern "C" int munmap(void* start, size_t length) __THROW {
  MallocHook::InvokeMunmapHook(start, length);
  int result;
  if (!MallocHook::InvokeMunmapReplacement(start, length, &result)) {
    result = MALLOC_HOOK_SYSCALL(SYS_munmap, start, length);
  }

  return result;
}

extern "C" void* sbrk(intptr_t increment) __THROW {
  MallocHook::InvokePreSbrkHook(increment);
  void *result = do_sbrk(increment);
  MallocHook::InvokeSbrkHook(result, increment);
  return result;
}

/*static*/void* MallocHook::UnhookedMMap(void *start, size_t length, int prot,
                                         int flags, int fd, off_t offset) {
  void* result;
  if (!MallocHook::InvokeMmapReplacement(
	  start, length, prot, flags, fd, offset, &result)) {
    result = do_mmap(start, length, prot, flags, fd, offset);
  }

  return result;
}

/*static*/int MallocHook::UnhookedMUnmap(void *start, size_t length) {
  int result;
  if (!MallocHook::InvokeMunmapReplacement(start, length, &result)) {
    result = MALLOC_HOOK_SYSCALL(SYS_munmap, start, length);
  }
  return result;
}

#undef MALLOC_HOOK_SYSCALL