/* Support for memory-mapped windows into a BFD.
   Copyright 1995, 1996, 2001, 2002 Free Software Foundation, Inc.
   Written by Cygnus Support.

This file is part of BFD, the Binary File Descriptor library.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#include "sysdep.h"

#include "bfd.h"
#include "libbfd.h"

#undef HAVE_MPROTECT

#if HAVE_MMAP || HAVE_MPROTECT || HAVE_MADVISE
#include <sys/types.h>
#include <sys/mman.h>
#endif

#undef MAP_SHARED
#define MAP_SHARED MAP_PRIVATE

#ifndef MAP_FILE
#define MAP_FILE 0
#endif

#ifndef HAVE_GETPAGESIZE
#define getpagesize() 2048
#endif

static bfd_boolean _bfd_get_file_window_mmap
PARAMS ((bfd *abfd, ufile_ptr offset, bfd_size_type size,
	 bfd_window *windowp, bfd_window_internal *i, bfd_boolean writable));
static bfd_boolean _bfd_get_file_window_malloc
PARAMS ((bfd *abfd, ufile_ptr offset, bfd_size_type size,
	 bfd_window *windowp, bfd_window_internal *i, bfd_boolean writable));

/* The idea behind the next and refcount fields is that one mapped
   region can suffice for multiple read-only windows or multiple
   non-overlapping read-write windows.  It's not implemented yet
   though.  */

/*
INTERNAL_DEFINITION

.struct _bfd_window_internal {
.  struct _bfd_window_internal *next;
.  PTR data;
.  bfd_size_type size;
.  int refcount : 31;		{* should be enough...  *}
.  unsigned mapped : 1;		{* 1 = mmap, 0 = malloc *}
.};
*/

void
bfd_init_window (windowp)
     bfd_window *windowp;
{
  windowp->data = 0;
  windowp->i = 0;
  windowp->size = 0;
}

/* Currently, if USE_MMAP is undefined, none if the window stuff is
   used.  Okay, so it's mis-named.  At least the command-line option
   "--without-mmap" is more obvious than "--without-windows" or some
   such.  */

static int debug_windows;

void
bfd_free_window (windowp)
     bfd_window *windowp;
{
  bfd_window_internal *i = windowp->i;

  windowp->i = 0;
  windowp->data = 0;

  if (i == 0)
    return;

  i->refcount--;
  if (debug_windows)
    fprintf (stderr, "freeing window @%p<%p,%lx,%p>\n",
	     windowp, windowp->data, windowp->size, windowp->i);
  if (i->refcount > 0)
    return;

  switch (i->mapped) {

  case 2:
      i->data = NULL;
      break;

  case 1:
#if HAVE_MMAP
    munmap (i->data, i->size);
    i->data = NULL;
#else
    abort ();
#endif

  case 0:
#if HAVE_MPROTECT
    mprotect (i->data, i->size, PROT_READ | PROT_WRITE);
#endif
    free (i->data);
    i->data = NULL;
    break;

  default:
    BFD_ASSERT ((i->mapped == 0) || (i->mapped == 1) || (i->mapped == 2));
  }

  /* There should be no more references to i at this point.  */
  free (i);
}

#if HAVE_MMAP
static bfd_boolean
_bfd_get_file_window_mmap (abfd, offset, size, windowp, i, writable)
     bfd *abfd;
     ufile_ptr offset;
     bfd_size_type size;
     bfd_window *windowp;
     bfd_window_internal *i;
     bfd_boolean writable;
{
  static size_t pagesize;

  /* Make sure we know the page size, so we can be friendly to mmap.  */
  if (pagesize == 0)
    pagesize = getpagesize ();
  if (pagesize == 0)
    abort ();

  if (i->data != 0 && i->mapped != 1)
    return FALSE;

  {
    file_ptr file_offset, offset2;
    size_t real_size;
    int fd;
    FILE *f;

    /* Find the real file and the real offset into it.  */
    while (abfd->my_archive != NULL)
      {
	offset += abfd->origin;
	abfd = abfd->my_archive;
      }
    f = bfd_cache_lookup (abfd);
    fd = fileno (f);

    /* Compute offsets and size for mmap and for the user's data.  */
    offset2 = offset % pagesize;
    if (offset2 < 0)
      abort ();
    file_offset = offset - offset2;
    real_size = offset + size - file_offset;
    real_size = real_size + pagesize - 1;
    real_size -= real_size % pagesize;

    /* If we're re-using a memory region, make sure it's big enough.  */
    if (i->data && i->size < size)
      {
	munmap (i->data, i->size);
	i->data = 0;
      }
    i->data = mmap (i->data, real_size,
		    writable ? PROT_WRITE | PROT_READ : PROT_READ,
		    (writable
		     ? MAP_FILE | MAP_PRIVATE
		     : MAP_FILE | MAP_SHARED),
		    fd, file_offset);
    if (i->data == (PTR) -1)
      {
	/* An error happened.  Report it, or try using malloc, or
	   something.  */
	bfd_set_error (bfd_error_system_call);
	i->data = 0;
	windowp->data = 0;
	if (debug_windows)
	  fprintf (stderr, "\t\tmmap failed!\n");
	return FALSE;
      }
    if (debug_windows)
      fprintf (stderr, "\n\tmapped %ld at %p, offset is %ld\n",
	       (long) real_size, i->data, (long) offset2);
    i->size = real_size;
    windowp->data = (PTR) ((bfd_byte *) i->data + offset2);
    windowp->size = size;
    i->mapped = 1;
    return TRUE;
  }
}
#endif /* HAVE_MMAP */

static bfd_boolean
_bfd_get_file_window_malloc (abfd, offset, size, windowp, i, writable)
     bfd *abfd;
     ufile_ptr offset;
     bfd_size_type size;
     bfd_window *windowp;
     bfd_window_internal *i;
     bfd_boolean writable ATTRIBUTE_UNUSED;
{
  static size_t pagesize;
  size_t size_to_alloc = size;

  /* Make sure we know the page size, so we can be friendly to mmap.  */
  if (pagesize == 0)
    pagesize = getpagesize ();
  if (pagesize == 0)
    abort ();

#if HAVE_MPROTECT
  if (!writable)
    {
      size_to_alloc += pagesize - 1;
      size_to_alloc -= size_to_alloc % pagesize;
    }
#endif

  if (debug_windows)
    fprintf (stderr, "\n\t%s(%6ld)",
	     i->data ? "realloc" : " malloc", (long) size_to_alloc);
  i->data = (PTR) bfd_realloc (i->data, size_to_alloc);
  if (debug_windows)
    fprintf (stderr, "\t-> %p\n", i->data);
  i->refcount = 1;
  if (i->data == NULL)
    {
      if (size_to_alloc == 0)
	return TRUE;
      bfd_set_error (bfd_error_no_memory);
      return FALSE;
    }
  if (bfd_seek (abfd, offset, SEEK_SET) != 0)
    return FALSE;
  i->size = bfd_bread (i->data, size, abfd);
  if (i->size != size)
    return FALSE;
  i->mapped = 0;

#if HAVE_MPROTECT
  if (!writable)
    {
      if (debug_windows)
	fprintf (stderr, "\tmprotect (%p, %ld, PROT_READ)\n", i->data,
		 (long) i->size);
      mprotect (i->data, i->size, PROT_READ);
    }
#endif

  windowp->data = i->data;
  windowp->size = i->size;
  return TRUE;
}

bfd_boolean
bfd_get_file_window (abfd, offset, size, windowp, writable)
     bfd *abfd;
     ufile_ptr offset;
     bfd_size_type size;
     bfd_window *windowp;
     bfd_boolean writable;
{
  bfd_window_internal *i = windowp->i;

  if (debug_windows)
    fprintf (stderr, "bfd_get_file_window (%p, %6ld, %6ld, %p<%p,%lx,%p>, %d)",
	     abfd, (long) offset, (long) size,
	     windowp, windowp->data, (unsigned long) windowp->size,
	     windowp->i, writable);

  BFD_ASSERT (i == NULL);

  if (i == NULL)
    {
      windowp->i = i = (bfd_window_internal *) bfd_zmalloc (sizeof (bfd_window_internal));
      if (i == 0)
	return FALSE;
      i->data = 0;
    }

  if ((abfd->flags & BFD_IO_FUNCS) != 0)
    {
      if (! _bfd_get_file_window_malloc (abfd, offset, size, windowp, i, writable))
	return FALSE;
    }
  else if ((abfd->flags & BFD_IN_MEMORY) != 0) 
    {
      struct bfd_in_memory *bim = (struct bfd_in_memory *) abfd->iostream;
      BFD_ASSERT (bim != NULL);

      if ((offset > bim->size) || ((bim->size - offset) < size))
	{
	  bfd_set_error (bfd_error_file_truncated);
	  return FALSE;
	}
      
      i->next = NULL;
      i->data = bim->buffer + offset;
      i->size = size;
      i->refcount = 1;
      i->mapped = 2;

      return TRUE;
    }
  else
    {
#if HAVE_MMAP
      if (! _bfd_get_file_window_mmap (abfd, offset, size, windowp, i, writable))
	return FALSE;
#else
      if (! _bfd_get_file_window_malloc (abfd, offset, size, windowp, i, writable))
	return FALSE;
#endif
    }

  return TRUE;
}