newlib-cygwin/winsup/cygwin/mmap.cc

/* mmap.cc

   Copyright 1996, 1997, 1998, 2000, 2001 Cygnus Solutions.

This file is part of Cygwin.

This software is a copyrighted work licensed under the terms of the
Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
details. */

#include "winsup.h"
#include <unistd.h>
#include <stdlib.h>
#include <stddef.h>
#include <sys/mman.h>
#include <errno.h>
#include "fhandler.h"
#include "dtable.h"
#include "cygerrno.h"
#include "cygheap.h"
#include "sync.h"
#include "sigproc.h"
#include "pinfo.h"
#include "security.h"
#include "sys/cygwin.h"

#define PAGE_CNT(bytes) howmany(bytes,getpagesize())

#define PGBITS		(sizeof(DWORD)*8)
#define MAPSIZE(pages)	howmany(pages,PGBITS)

#define MAP_SET(n)	(map_map_[(n)/PGBITS] |= (1L << ((n) % PGBITS)))
#define MAP_CLR(n)	(map_map_[(n)/PGBITS] &= ~(1L << ((n) % PGBITS)))
#define MAP_ISSET(n)	(map_map_[(n)/PGBITS] & (1L << ((n) % PGBITS)))

/*
 * Simple class used to keep a record of all current
 * mmap areas in a process. Needed so that
 * they can be duplicated after a fork().
 */

class mmap_record
{
  private:
    int fdesc_;
    HANDLE mapping_handle_;
    int devtype_;
    DWORD access_mode_;
    DWORD offset_;
    DWORD size_to_map_;
    caddr_t base_address_;
    DWORD *map_map_;

  public:
    mmap_record (int fd, HANDLE h, DWORD ac, DWORD o, DWORD s, caddr_t b) :
       fdesc_ (fd),
       mapping_handle_ (h),
       devtype_ (0),
       access_mode_ (ac),
       offset_ (o),
       size_to_map_ (s),
       base_address_ (b),
       map_map_ (NULL)
      {
        if (fd >= 0 && !cygheap->fdtab.not_open (fd))
	  devtype_ = cygheap->fdtab[fd]->get_device ();
      }

    /* Default Copy constructor/operator=/destructor are ok */

    /* Simple accessors */
    int get_fd () const { return fdesc_; }
    HANDLE get_handle () const { return mapping_handle_; }
    DWORD get_device () const { return devtype_; }
    DWORD get_access () const { return access_mode_; }
    DWORD get_offset () const { return offset_; }
    DWORD get_size () const { return size_to_map_; }
    caddr_t get_address () const { return base_address_; }
    DWORD *get_map () const { return map_map_; }

    void alloc_map ()
      {
        /* Allocate one bit per page */
        map_map_ = (DWORD *) calloc (MAPSIZE(PAGE_CNT (size_to_map_)),
				     sizeof (DWORD));
	if (os_being_run == winNT)
	  {
	    DWORD old_prot;
	    if (!VirtualProtect (base_address_, size_to_map_,
	                         PAGE_NOACCESS, &old_prot))
	      syscall_printf ("-1 = alloc_map (): %E");
          }
      }
    void free_map () { if (map_map_) free (map_map_); }

    DWORD find_empty (DWORD pages);
    DWORD map_map (DWORD off, DWORD len);
    BOOL unmap_map (caddr_t addr, DWORD len);
    void fixup_map (void);

    fhandler_base *alloc_fh ();
    void free_fh (fhandler_base *fh);
};

DWORD
mmap_record::find_empty (DWORD pages)
{
  DWORD mapped_pages = PAGE_CNT (size_to_map_);
  DWORD start;

  for (start = 0; start <= mapped_pages - pages; ++start)
    if (!MAP_ISSET (start))
      {
        DWORD cnt;
        for (cnt = 0; cnt < pages; ++cnt)
	  if (MAP_ISSET (start + cnt))
	    break;
        if (cnt >= pages)
	  return start;
      }
  return (DWORD)-1;
}

DWORD
mmap_record::map_map (DWORD off, DWORD len)
{
  DWORD prot, old_prot;
  switch (access_mode_)
    {
    case FILE_MAP_WRITE:
      prot = PAGE_READWRITE;
      break;
    case FILE_MAP_READ:
      prot = PAGE_READONLY;
      break;
    default:
      prot = PAGE_WRITECOPY;
      break;
    }

  len = PAGE_CNT (len);
  if (fdesc_ == -1 && !off)
    {
      off = find_empty (len);
      if (off != (DWORD)-1)
        {
	  if (os_being_run == winNT
              && !VirtualProtect (base_address_ + off * getpagesize (),
	                          len * getpagesize (), prot, &old_prot))
	    syscall_printf ("-1 = map_map (): %E");

	  while (len-- > 0)
	    MAP_SET (off + len);
	  return off * getpagesize ();
	}
      return 0L;
    }
  off -= offset_;
  DWORD start = off / getpagesize ();
  if (os_being_run == winNT
      && !VirtualProtect (base_address_ + start * getpagesize (),
		          len * getpagesize (), prot, &old_prot))
    syscall_printf ("-1 = map_map (): %E");

  for (; len-- > 0; ++start)
    MAP_SET (start);
  return off;
}

BOOL
mmap_record::unmap_map (caddr_t addr, DWORD len)
{
  DWORD old_prot;
  DWORD off = addr - base_address_;
  off /= getpagesize ();
  len = PAGE_CNT (len);
  if (os_being_run == winNT
      && !VirtualProtect (base_address_ + off * getpagesize (),
		          len * getpagesize (), PAGE_NOACCESS, &old_prot))
    syscall_printf ("-1 = unmap_map (): %E");

  for (; len-- > 0; ++off)
    MAP_CLR (off);
  /* Return TRUE if all pages are free'd which may result in unmapping
     the whole chunk. */
  for (len = MAPSIZE(PAGE_CNT (size_to_map_)); len > 0; )
    if (map_map_[--len])
      return FALSE;
  return TRUE;
}

void
mmap_record::fixup_map ()
{
  if (os_being_run != winNT)
    return;

  DWORD prot, old_prot;
  switch (access_mode_)
    {
    case FILE_MAP_WRITE:
      prot = PAGE_READWRITE;
      break;
    case FILE_MAP_READ:
      prot = PAGE_READONLY;
      break;
    default:
      prot = PAGE_WRITECOPY;
      break;
    }

  for (DWORD off = PAGE_CNT (size_to_map_); off > 0; --off)
    VirtualProtect (base_address_ + off * getpagesize (),
	            getpagesize (),
		    MAP_ISSET (off - 1) ? prot : PAGE_NOACCESS,
		    &old_prot);
}

static fhandler_disk_file fh_paging_file (NULL);

fhandler_base *
mmap_record::alloc_fh ()
{
  if (get_fd () == -1)
    {
      fh_paging_file.set_io_handle (INVALID_HANDLE_VALUE);
      return &fh_paging_file;
    }

  /* The file descriptor could have been closed or, even
     worse, could have been reused for another file before
     the call to fork(). This requires creating a fhandler
     of the correct type to be sure to call the method of the
     correct class. */
  return cygheap->fdtab.build_fhandler (-1, get_device (), "", 0);
}

void
mmap_record::free_fh (fhandler_base *fh)
{
  if (get_fd () != -1)
    cfree (fh);
}

class list {
public:
  mmap_record *recs;
  int nrecs, maxrecs;
  int fd;
  DWORD hash;
  list ();
  ~list ();
  mmap_record *add_record (mmap_record r);
  void erase (int i);
  mmap_record *match (DWORD off, DWORD len);
  off_t match (caddr_t addr, DWORD len, off_t start);
};

list::list ()
: nrecs (0), maxrecs (10), fd (0), hash (0)
{
  recs = (mmap_record *) malloc (10 * sizeof(mmap_record));
}

list::~list ()
{
  for (mmap_record *rec = recs; nrecs-- > 0; ++rec)
    rec->free_map ();
  free (recs);
}

mmap_record *
list::add_record (mmap_record r)
{
  if (nrecs == maxrecs)
    {
      maxrecs += 5;
      recs = (mmap_record *) realloc (recs, maxrecs * sizeof (mmap_record));
    }
  recs[nrecs] = r;
  recs[nrecs].alloc_map ();
  return recs + nrecs++;
}

/* Used in mmap() */
mmap_record *
list::match (DWORD off, DWORD len)
{
  if (fd == -1 && !off)
    {
      len = PAGE_CNT (len);
      for (int i = 0; i < nrecs; ++i)
	if (recs[i].find_empty (len) != (DWORD)-1)
	  return recs + i;
    }
  else
    {
      for (int i = 0; i < nrecs; ++i)
	if (off >= recs[i].get_offset ()
	    && off + len <= recs[i].get_offset () + recs[i].get_size ())
	  return recs + i;
    }
  return NULL;
}

/* Used in munmap() */
off_t
list::match (caddr_t addr, DWORD len, off_t start)
{
  for (int i = start + 1; i < nrecs; ++i)
    if (addr >= recs[i].get_address ()
        && addr + len <= recs[i].get_address () + recs[i].get_size ())
      return i;
  return (off_t)-1;
}

void
list::erase (int i)
{
  recs[i].free_map ();
  for (; i < nrecs-1; i++)
    recs[i] = recs[i+1];
  nrecs--;
}

class map {
public:
  list **lists;
  int nlists, maxlists;
  map ();
  ~map ();
  list *get_list_by_fd (int fd);
  list *add_list (list *l, int fd);
  void erase (int i);
};

map::map ()
{
  lists = (list **) malloc (10 * sizeof(list *));
  nlists = 0;
  maxlists = 10;
}

map::~map ()
{
  free (lists);
}

list *
map::get_list_by_fd (int fd)
{
  int i;
  for (i=0; i<nlists; i++)
#if 0 /* The fd isn't sufficient since it could already be another file. */
    if (lists[i]->fd == fd
#else /* so we use the name hash value to identify the file unless
         it's not an anonymous mapping. */
    if ((fd == -1 && lists[i]->fd == -1)
        || (fd != -1 && lists[i]->hash == cygheap->fdtab[fd]->get_namehash ()))
#endif
      return lists[i];
  return 0;
}

list *
map::add_list (list *l, int fd)
{
  l->fd = fd;
  if (fd != -1)
    l->hash = cygheap->fdtab[fd]->get_namehash ();
  if (nlists == maxlists)
    {
      maxlists += 5;
      lists = (list **) realloc (lists, maxlists * sizeof (list *));
    }
  lists[nlists++] = l;
  return lists[nlists-1];
}

void
map::erase (int i)
{
  for (; i < nlists-1; i++)
    lists[i] = lists[i+1];
  nlists--;
}

/*
 * Code to keep a record of all mmap'ed areas in a process.
 * Needed to duplicate tham in a child of fork().
 * mmap_record classes are kept in an STL list in an STL map, keyed
 * by file descriptor. This is *NOT* duplicated accross a fork(), it
 * needs to be specially handled by the fork code.
 */

static map *mmapped_areas;

extern "C"
caddr_t
mmap (caddr_t addr, size_t len, int prot, int flags, int fd, off_t off)
{
  syscall_printf ("addr %x, len %d, prot %x, flags %x, fd %d, off %d",
		  addr, len, prot, flags, fd, off);

  static DWORD granularity;
  if (!granularity)
    {
      SYSTEM_INFO si;
      GetSystemInfo (&si);
      granularity = si.dwAllocationGranularity;
    }

  /* Error conditions according to SUSv2 */
  if (off % getpagesize ()
      || (!(flags & MAP_SHARED) && !(flags & MAP_PRIVATE))
      || ((flags & MAP_SHARED) && (flags & MAP_PRIVATE))
      || ((flags & MAP_FIXED) && ((DWORD)addr % granularity))
      || !len)
    {
      set_errno (EINVAL);
      syscall_printf ("-1 = mmap(): EINVAL");
      return MAP_FAILED;
    }

  DWORD access = (prot & PROT_WRITE) ? FILE_MAP_WRITE : FILE_MAP_READ;
  /* copy-on-write doesn't work correctly on 9x. To have at least read
     access we use *READ mapping on 9x when appropriate. It will still
     fail when needing write access, though. */
  if ((flags & MAP_PRIVATE) && (os_being_run == winNT || (prot & ~PROT_READ)))
    access = FILE_MAP_COPY;

  SetResourceLock(LOCK_MMAP_LIST, READ_LOCK | WRITE_LOCK, "mmap");

#if 0
  /* Windows 95 does not have fixed addresses */
  /*
   * CV: This assumption isn't correct. See Microsoft Platform SDK, Memory,
   * description of call `MapViewOfFileEx'.
   */
  if ((os_being_run != winNT) && (flags & MAP_FIXED))
    {
      set_errno (EINVAL);
      syscall_printf ("-1 = mmap(): win95 and MAP_FIXED");
      return MAP_FAILED;
    }
#endif

  if (mmapped_areas == NULL)
    {
      /* First mmap call, create STL map */
      mmapped_areas = new map;
      if (mmapped_areas == NULL)
	{
	  set_errno (ENOMEM);
	  syscall_printf ("-1 = mmap(): ENOMEM");
	  ReleaseResourceLock(LOCK_MMAP_LIST, READ_LOCK | WRITE_LOCK, "mmap");
	  return MAP_FAILED;
	}
    }

  if (flags & MAP_ANONYMOUS)
    fd = -1;

  /* Map always in multipliers of `granularity'-sized chunks. */
  DWORD gran_off = off & ~(granularity - 1);
  DWORD gran_len = howmany (len, granularity) * granularity;

  fhandler_base *fh = NULL;
  caddr_t base = addr;
  HANDLE h;

  if (fd != -1)
    {
      /* Ensure that fd is open */
      if (cygheap->fdtab.not_open (fd))
	{
	  set_errno (EBADF);
	  syscall_printf ("-1 = mmap(): EBADF");
	  ReleaseResourceLock(LOCK_MMAP_LIST, READ_LOCK | WRITE_LOCK, "mmap");
	  return MAP_FAILED;
	}
      fh = cygheap->fdtab[fd];
      if (fh->get_device () == FH_DISK)
        {
	  DWORD fsiz = GetFileSize (fh->get_handle (), NULL);
	  fsiz -= gran_off;
	  if (gran_len > fsiz)
	    gran_len = fsiz;
	}
      else if (fh->get_device () == FH_ZERO)
	/* mmap /dev/zero is like MAP_ANONYMOUS. */
        fd = -1;
    }
  if (fd == -1)
    {
      fh_paging_file.set_io_handle (INVALID_HANDLE_VALUE);
      fh = &fh_paging_file;
    }

  list *l = mmapped_areas->get_list_by_fd (fd);

  /* First check if this mapping matches into the chunk of another
     already performed mapping. Only valid for MAP_ANON in a special
     case of MAP_PRIVATE. */
  if (l && fd == -1 && off == 0)
    {
      mmap_record *rec;
      if ((rec = l->match (off, len)) != NULL)
	{
	  off = rec->map_map (off, len);
	  caddr_t ret = rec->get_address () + off;
	  syscall_printf ("%x = mmap() succeeded", ret);
	  ReleaseResourceLock(LOCK_MMAP_LIST, READ_LOCK | WRITE_LOCK, "mmap");
	  return ret;
	}
    }

  h = fh->mmap (&base, gran_len, access, flags, gran_off);

  if (h == INVALID_HANDLE_VALUE)
    {
      ReleaseResourceLock(LOCK_MMAP_LIST, READ_LOCK | WRITE_LOCK, "mmap");
      return MAP_FAILED;
    }

  /* Now we should have a successfully mmapped area.
     Need to save it so forked children can reproduce it.
  */
  if (fd == -1)
    gran_len = PAGE_CNT (gran_len) * getpagesize ();
  mmap_record mmap_rec (fd, h, access, gran_off, gran_len, base);

  /* Get list of mmapped areas for this fd, create a new one if
     one does not exist yet.
  */
  if (l == 0)
    {
      /* Create a new one */
      l = new list;
      if (l == 0)
        {
          fh->munmap (h, base, gran_len);
          set_errno (ENOMEM);
          syscall_printf ("-1 = mmap(): ENOMEM");
          ReleaseResourceLock(LOCK_MMAP_LIST, READ_LOCK | WRITE_LOCK, "mmap");
          return MAP_FAILED;
        }
      l = mmapped_areas->add_list (l, fd);
  }

  /* Insert into the list */
  mmap_record *rec = l->add_record (mmap_rec);
  off = rec->map_map (off, len);
  caddr_t ret = rec->get_address () + off;
  syscall_printf ("%x = mmap() succeeded", ret);
  ReleaseResourceLock(LOCK_MMAP_LIST, READ_LOCK | WRITE_LOCK, "mmap");
  return ret;
}

/* munmap () removes an mmapped area.  It insists that base area
   requested is the same as that mmapped, error if not. */

extern "C"
int
munmap (caddr_t addr, size_t len)
{
  syscall_printf ("munmap (addr %x, len %d)", addr, len);

  /* Error conditions according to SUSv2 */
  if (((DWORD)addr % getpagesize ()) || !len)
    {
      set_errno (EINVAL);
      syscall_printf ("-1 = munmap(): Invalid parameters");
      return -1;
    }

  SetResourceLock(LOCK_MMAP_LIST, WRITE_LOCK | READ_LOCK, "munmap");
  /* Check if a mmap'ed area was ever created */
  if (mmapped_areas == NULL)
    {
      syscall_printf ("-1 = munmap(): mmapped_areas == NULL");
      set_errno (EINVAL);
      ReleaseResourceLock(LOCK_MMAP_LIST, WRITE_LOCK | READ_LOCK, "munmap");
      return -1;
    }

  /* Iterate through the map, looking for the mmapped area.
     Error if not found. */

  for (int it = 0; it < mmapped_areas->nlists; ++it)
    {
      list *l = mmapped_areas->lists[it];
      if (l)
	{
	  off_t li = -1;
	  if ((li = l->match(addr, len, li)) >= 0)
	    {
	      mmap_record *rec = l->recs + li;
	      if (rec->unmap_map (addr, len))
	        {
		  fhandler_base *fh = rec->alloc_fh ();
                  fh->munmap (rec->get_handle (), addr, len);
		  rec->free_fh (fh);

		  /* Delete the entry. */
		  l->erase (li);
		}
	      syscall_printf ("0 = munmap(): %x", addr);
	      ReleaseResourceLock(LOCK_MMAP_LIST, WRITE_LOCK | READ_LOCK, "munmap");
	      return 0;
	    }
	}
    }

  set_errno (EINVAL);
  syscall_printf ("-1 = munmap(): EINVAL");

  ReleaseResourceLock(LOCK_MMAP_LIST, WRITE_LOCK | READ_LOCK, "munmap");
  return -1;
}

/* Sync file with memory. Ignore flags for now. */

extern "C"
int
msync (caddr_t addr, size_t len, int flags)
{
  syscall_printf ("addr = %x, len = %d, flags = %x",
		  addr, len, flags);

  /* However, check flags for validity. */
  if ((flags & ~(MS_ASYNC | MS_SYNC | MS_INVALIDATE))
      || ((flags & MS_ASYNC) && (flags & MS_SYNC)))
    {
      syscall_printf ("-1 = msync(): Invalid flags");
      set_errno (EINVAL);
      return -1;
    }

  SetResourceLock(LOCK_MMAP_LIST, WRITE_LOCK | READ_LOCK, "msync");
  /* Check if a mmap'ed area was ever created */
  if (mmapped_areas == NULL)
    {
      syscall_printf ("-1 = msync(): mmapped_areas == NULL");
      set_errno (EINVAL);
      ReleaseResourceLock(LOCK_MMAP_LIST, WRITE_LOCK | READ_LOCK, "msync");
      return -1;
    }

  /* Iterate through the map, looking for the mmapped area.
     Error if not found. */

  for (int it = 0; it < mmapped_areas->nlists; ++it)
    {
      list *l = mmapped_areas->lists[it];
      if (l != 0)
	{
	  for (int li = 0; li < l->nrecs; ++li)
	    {
	      mmap_record *rec = l->recs + li;
	      if (rec->get_address () == addr)
		{
		  fhandler_base *fh = rec->alloc_fh ();
                  int ret = fh->msync (rec->get_handle (), addr, len, flags);
		  rec->free_fh (fh);

                  if (ret)
		    syscall_printf ("%d = msync(): %E", ret);
                  else
		    syscall_printf ("0 = msync()");

		  ReleaseResourceLock(LOCK_MMAP_LIST, WRITE_LOCK | READ_LOCK, "msync");
		  return 0;
		}
	     }
	 }
     }

  /* SUSv2: Return code if indicated memory was not mapped is ENOMEM. */
  set_errno (ENOMEM);
  syscall_printf ("-1 = msync(): ENOMEM");

  ReleaseResourceLock(LOCK_MMAP_LIST, WRITE_LOCK | READ_LOCK, "msync");
  return -1;
}

/*
 * Base implementation:
 *
 * `mmap' returns ENODEV as documented in SUSv2.
 * In contrast to the global function implementation, the member function
 * `mmap' has to return the mapped base address in `addr' and the handle to
 * the mapping object as return value. In case of failure, the fhandler
 * mmap has to close that handle by itself and return INVALID_HANDLE_VALUE.
 *
 * `munmap' and `msync' get the handle to the mapping object as first parameter
 * additionally.
*/
HANDLE
fhandler_base::mmap (caddr_t *addr, size_t len, DWORD access,
                     int flags, off_t off)
{
  set_errno (ENODEV);
  return INVALID_HANDLE_VALUE;
}

int
fhandler_base::munmap (HANDLE h, caddr_t addr, size_t len)
{
  set_errno (ENODEV);
  return -1;
}

int
fhandler_base::msync (HANDLE h, caddr_t addr, size_t len, int flags)
{
  set_errno (ENODEV);
  return -1;
}

BOOL
fhandler_base::fixup_mmap_after_fork (HANDLE h, DWORD access, DWORD offset,
				      DWORD size, void *address)
{
  set_errno (ENODEV);
  return -1;
}

/* Implementation for disk files. */
HANDLE
fhandler_disk_file::mmap (caddr_t *addr, size_t len, DWORD access,
                          int flags, off_t off)
{
  DWORD protect;

  if (access & FILE_MAP_COPY)
    protect = PAGE_WRITECOPY;
  else if (access & FILE_MAP_WRITE)
    protect = PAGE_READWRITE;
  else
    protect = PAGE_READONLY;

  HANDLE h;

  /* On 9x/ME try first to open the mapping by name when opening a
     shared file object. This is needed since 9x/ME only shares
     objects between processes by name. What a mess... */
  if (os_being_run != winNT
      && get_handle () != INVALID_HANDLE_VALUE
      && get_device () == FH_DISK
      && !(access & FILE_MAP_COPY))
    {
      /* Grrr, the whole stuff is just needed to try to get a reliable
         mapping of the same file. Even that uprising isn't bullet
	 proof but it does it's best... */
      char namebuf[MAX_PATH];
      cygwin_conv_to_full_posix_path (get_name (), namebuf);
      for (int i = strlen (namebuf) - 1; i >= 0; --i)
        namebuf[i] = cyg_tolower (namebuf [i]);

      if (!(h = OpenFileMapping (access, TRUE, namebuf)))
	h = CreateFileMapping (get_handle(), &sec_none, protect, 0, 0, namebuf);
    }
  else
    h = CreateFileMapping (get_handle (), &sec_none, protect, 0,
			   get_handle () == INVALID_HANDLE_VALUE ? len : 0,
			   NULL);
  if (!h)
    {
      __seterrno ();
      syscall_printf ("-1 = mmap(): CreateFileMapping failed with %E");
      return INVALID_HANDLE_VALUE;
    }

  void *base = MapViewOfFileEx (h, access, 0, off, len,
                               (flags & MAP_FIXED) ? *addr : NULL);

  if (!base || ((flags & MAP_FIXED) && base != *addr))
    {
      if (!base)
        {
          __seterrno ();
          syscall_printf ("-1 = mmap(): MapViewOfFileEx failed with %E");
        }
      else
        {
	  set_errno (EINVAL);
          syscall_printf ("-1 = mmap(): address shift with MAP_FIXED given");
        }
      CloseHandle (h);
      return INVALID_HANDLE_VALUE;
    }

  *addr = (caddr_t) base;
  return h;
}

int
fhandler_disk_file::munmap (HANDLE h, caddr_t addr, size_t len)
{
  UnmapViewOfFile (addr);
  CloseHandle (h);
  return 0;
}

int
fhandler_disk_file::msync (HANDLE h, caddr_t addr, size_t len, int flags)
{
  if (FlushViewOfFile (addr, len) == 0)
    {
      __seterrno ();
      return -1;
    }
  return 0;
}

BOOL
fhandler_disk_file::fixup_mmap_after_fork (HANDLE h, DWORD access, DWORD offset,
					   DWORD size, void *address)
{
  /* Re-create the MapViewOfFileEx call */
  void *base = MapViewOfFileEx (h, access, 0, offset, size, address);
  return base == address;
}

/* Set memory protection */

extern "C"
int
mprotect (caddr_t addr, size_t len, int prot)
{
  DWORD old_prot;
  DWORD new_prot = 0;

  syscall_printf ("mprotect (addr %x, len %d, prot %x)", addr, len, prot);

  if (prot == PROT_NONE)
    new_prot = PAGE_NOACCESS;
  else
    {
      switch (prot)
	{
	  case PROT_READ | PROT_WRITE | PROT_EXEC:
	    new_prot = PAGE_EXECUTE_READWRITE;
	    break;
	  case PROT_READ | PROT_WRITE:
	    new_prot = PAGE_READWRITE;
	    break;
	  case PROT_READ | PROT_EXEC:
	    new_prot = PAGE_EXECUTE_READ;
	    break;
	  case PROT_READ:
	    new_prot = PAGE_READONLY;
	    break;
	  default:
	    syscall_printf ("-1 = mprotect (): invalid prot value");
	    set_errno (EINVAL);
	    return -1;
	 }
     }

  if (VirtualProtect (addr, len, new_prot, &old_prot) == 0)
    {
      __seterrno ();
      syscall_printf ("-1 = mprotect (): %E");
      return -1;
    }

  syscall_printf ("0 = mprotect ()");
  return 0;
}

/*
 * Call to re-create all the file mappings in a forked
 * child. Called from the child in initialization. At this
 * point we are passed a valid mmapped_areas map, and all the
 * HANDLE's are valid for the child, but none of the
 * mapped areas are in our address space. We need to iterate
 * through the map, doing the MapViewOfFile calls.
 */

int __stdcall
fixup_mmaps_after_fork ()
{

  debug_printf ("recreate_mmaps_after_fork, mmapped_areas %p", mmapped_areas);

  /* Check if a mmapped area was ever created */
  if (mmapped_areas == NULL)
    return 0;

  /* Iterate through the map */
  for (int it = 0; it < mmapped_areas->nlists; ++it)
    {
      list *l = mmapped_areas->lists[it];
      if (l != 0)
	{
	  int li;
	  for (li = 0; li < l->nrecs; ++li)
	    {
	      mmap_record *rec = l->recs + li;

	      debug_printf ("fd %d, h %x, access %x, offset %d, size %d, address %p",
		  rec->get_fd (), rec->get_handle (), rec->get_access (),
		  rec->get_offset (), rec->get_size (), rec->get_address ());

	      fhandler_base *fh = rec->alloc_fh ();
	      BOOL ret = fh->fixup_mmap_after_fork (rec->get_handle (),
					            rec->get_access (),
					            rec->get_offset (),
					            rec->get_size (),
					            rec->get_address ());
	      rec->free_fh (fh);

	      if (!ret)
		{
		  system_printf ("base address fails to match requested address %p",
				 rec->get_address ());
		  return -1;
		}
	      rec->fixup_map ();
	    }
	}
    }

  debug_printf ("succeeded");
  return 0;
}