[deliverable/binutils-gdb.git] / bfd / bfdwin.c

/* Support for memory-mapped windows into a BFD.
   Copyright (C) 1995-2020 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 3 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., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

#include "sysdep.h"

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

/* Currently, if USE_MMAP is undefined, none of the window stuff is
   used.  Enabled by --with-mmap.  */

#ifdef USE_MMAP

#undef HAVE_MPROTECT /* code's not tested yet */

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

#ifndef MAP_FILE
#define MAP_FILE 0
#endif

static int debug_windows;

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

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

void
bfd_free_window (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, (unsigned long) windowp->size, windowp->i);
  if (i->refcount != 0)
    return;

  if (i->mapped)
    {
#ifdef HAVE_MMAP
      munmap (i->data, i->size);
      goto no_free;
#else
      abort ();
#endif
    }
#ifdef HAVE_MPROTECT
  mprotect (i->data, i->size, PROT_READ | PROT_WRITE);
#endif
  free (i->data);
#ifdef HAVE_MMAP
 no_free:
#endif
  i->data = 0;
  /* There should be no more references to i at this point.  */
  free (i);
}

static int ok_to_map = 1;

bfd_boolean
bfd_get_file_window (bfd *abfd,
		     file_ptr offset,
		     bfd_size_type size,
		     bfd_window *windowp,
		     bfd_boolean writable)
{
  static size_t pagesize;
  bfd_window_internal *i = windowp->i;
  bfd_size_type size_to_alloc = size;

  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);

  /* 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 == NULL)
    {
      i = bfd_zmalloc (sizeof (bfd_window_internal));
      if (i == NULL)
	return FALSE;
      i->data = NULL;
    }
#ifdef HAVE_MMAP
  if (ok_to_map
      && (i->data == NULL || i->mapped == 1)
      && (abfd->flags & BFD_IN_MEMORY) == 0)
    {
      file_ptr file_offset, offset2;
      size_t real_size;
      int fd;

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

      /* Seek into the file, to ensure it is open if cacheable.  */
      if (abfd->iostream == NULL
	  && (abfd->iovec == NULL
	      || abfd->iovec->bseek (abfd, offset, SEEK_SET) != 0))
	goto free_and_fail;

      fd = fileno ((FILE *) abfd->iostream);
      /* 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 != NULL && i->size < size)
	{
	  munmap (i->data, i->size);
	  i->data = NULL;
	}
      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 == (void *) -1)
	{
	  /* An error happened.  Report it, or try using malloc, or
	     something.  */
	  bfd_set_error (bfd_error_system_call);
	  windowp->data = 0;
	  if (debug_windows)
	    fprintf (stderr, "\t\tmmap failed!\n");
	  goto free_and_fail;
	}
      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 = (bfd_byte *) i->data + offset2;
      windowp->size = size;
      i->mapped = 1;
      i->refcount = 1;
      windowp->i = i;
      return TRUE;
    }
  else if (debug_windows)
    {
      if (ok_to_map)
	fprintf (stderr, _("not mapping: data=%lx mapped=%d\n"),
		 (unsigned long) i->data, (int) i->mapped);
      else
	fprintf (stderr, _("not mapping: env var not set\n"));
    }
#else
  ok_to_map = 0;
#endif

#ifdef 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 = bfd_realloc_or_free (i->data, size_to_alloc);
  if (debug_windows)
    fprintf (stderr, "\t-> %p\n", i->data);
  if (i->data == NULL)
    {
      if (size_to_alloc == 0)
	{
	  windowp->i = i;
	  return TRUE;
	}
      goto free_and_fail;
    }
  i->refcount = 1;
  if (bfd_seek (abfd, offset, SEEK_SET) != 0)
    goto free_and_fail;
  i->size = bfd_bread (i->data, size, abfd);
  if (i->size != size)
    goto free_and_fail;
  i->mapped = 0;
#ifdef 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;
  windowp->i = i;
  return TRUE;

 free_and_fail:
  /* We have a bfd_window_internal, but an error occurred.  Free it. */
  free (i);
  return FALSE;
}

#endif /* USE_MMAP */
Commit	Line	Data
	1	/* Support for memory-mapped windows into a BFD.
	2	Copyright (C) 1995-2020 Free Software Foundation, Inc.
	3	Written by Cygnus Support.
	4
	5	This file is part of BFD, the Binary File Descriptor library.
	6
	7	This program is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 3 of the License, or
	10	(at your option) any later version.
	11
	12	This program is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with this program; if not, write to the Free Software
	19	Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
	20	MA 02110-1301, USA. */
	21
	22	#include "sysdep.h"
	23
	24	#include "bfd.h"
	25	#include "libbfd.h"
	26
	27	/* Currently, if USE_MMAP is undefined, none of the window stuff is
	28	used. Enabled by --with-mmap. */
	29
	30	#ifdef USE_MMAP
	31
	32	#undef HAVE_MPROTECT /* code's not tested yet */
	33
	34	#if HAVE_MMAP \|\| HAVE_MPROTECT \|\| HAVE_MADVISE
	35	#include <sys/mman.h>
	36	#endif
	37
	38	#ifndef MAP_FILE
	39	#define MAP_FILE 0
	40	#endif
	41
	42	static int debug_windows;
	43
	44	/* The idea behind the next and refcount fields is that one mapped
	45	region can suffice for multiple read-only windows or multiple
	46	non-overlapping read-write windows. It's not implemented yet
	47	though. */
	48
	49	/*
	50	INTERNAL_DEFINITION
	51
	52	.struct _bfd_window_internal {
	53	. struct _bfd_window_internal *next;
	54	. void *data;
	55	. bfd_size_type size;
	56	. int refcount : 31; {* should be enough... *}
	57	. unsigned mapped : 1; {* 1 = mmap, 0 = malloc *}
	58	.};
	59	*/
	60
	61	void
	62	bfd_init_window (bfd_window *windowp)
	63	{
	64	windowp->data = 0;
	65	windowp->i = 0;
	66	windowp->size = 0;
	67	}
	68
	69	void
	70	bfd_free_window (bfd_window *windowp)
	71	{
	72	bfd_window_internal *i = windowp->i;
	73	windowp->i = 0;
	74	windowp->data = 0;
	75	if (i == 0)
	76	return;
	77	i->refcount--;
	78	if (debug_windows)
	79	fprintf (stderr, "freeing window @%p<%p,%lx,%p>\n",
	80	windowp, windowp->data, (unsigned long) windowp->size, windowp->i);
	81	if (i->refcount != 0)
	82	return;
	83
	84	if (i->mapped)
	85	{
	86	#ifdef HAVE_MMAP
	87	munmap (i->data, i->size);
	88	goto no_free;
	89	#else
	90	abort ();
	91	#endif
	92	}
	93	#ifdef HAVE_MPROTECT
	94	mprotect (i->data, i->size, PROT_READ \| PROT_WRITE);
	95	#endif
	96	free (i->data);
	97	#ifdef HAVE_MMAP
	98	no_free:
	99	#endif
	100	i->data = 0;
	101	/* There should be no more references to i at this point. */
	102	free (i);
	103	}
	104
	105	static int ok_to_map = 1;
	106
	107	bfd_boolean
	108	bfd_get_file_window (bfd *abfd,
	109	file_ptr offset,
	110	bfd_size_type size,
	111	bfd_window *windowp,
	112	bfd_boolean writable)
	113	{
	114	static size_t pagesize;
	115	bfd_window_internal *i = windowp->i;
	116	bfd_size_type size_to_alloc = size;
	117
	118	if (debug_windows)
	119	fprintf (stderr, "bfd_get_file_window (%p, %6ld, %6ld, %p<%p,%lx,%p>, %d)",
	120	abfd, (long) offset, (long) size,
	121	windowp, windowp->data, (unsigned long) windowp->size,
	122	windowp->i, writable);
	123
	124	/* Make sure we know the page size, so we can be friendly to mmap. */
	125	if (pagesize == 0)
	126	pagesize = getpagesize ();
	127	if (pagesize == 0)
	128	abort ();
	129
	130	if (i == NULL)
	131	{
	132	i = bfd_zmalloc (sizeof (bfd_window_internal));
	133	if (i == NULL)
	134	return FALSE;
	135	i->data = NULL;
	136	}
	137	#ifdef HAVE_MMAP
	138	if (ok_to_map
	139	&& (i->data == NULL \|\| i->mapped == 1)
	140	&& (abfd->flags & BFD_IN_MEMORY) == 0)
	141	{
	142	file_ptr file_offset, offset2;
	143	size_t real_size;
	144	int fd;
	145
	146	/* Find the real file and the real offset into it. */
	147	while (abfd->my_archive != NULL
	148	&& !bfd_is_thin_archive (abfd->my_archive))
	149	{
	150	offset += abfd->origin;
	151	abfd = abfd->my_archive;
	152	}
	153	offset += abfd->origin;
	154
	155	/* Seek into the file, to ensure it is open if cacheable. */
	156	if (abfd->iostream == NULL
	157	&& (abfd->iovec == NULL
	158	\|\| abfd->iovec->bseek (abfd, offset, SEEK_SET) != 0))
	159	goto free_and_fail;
	160
	161	fd = fileno ((FILE *) abfd->iostream);
	162	/* Compute offsets and size for mmap and for the user's data. */
	163	offset2 = offset % pagesize;
	164	if (offset2 < 0)
	165	abort ();
	166	file_offset = offset - offset2;
	167	real_size = offset + size - file_offset;
	168	real_size = real_size + pagesize - 1;
	169	real_size -= real_size % pagesize;
	170
	171	/* If we're re-using a memory region, make sure it's big enough. */
	172	if (i->data != NULL && i->size < size)
	173	{
	174	munmap (i->data, i->size);
	175	i->data = NULL;
	176	}
	177	i->data = mmap (i->data, real_size,
	178	writable ? PROT_WRITE \| PROT_READ : PROT_READ,
	179	(writable
	180	? MAP_FILE \| MAP_PRIVATE
	181	: MAP_FILE \| MAP_SHARED),
	182	fd, file_offset);
	183	if (i->data == (void *) -1)
	184	{
	185	/* An error happened. Report it, or try using malloc, or
	186	something. */
	187	bfd_set_error (bfd_error_system_call);
	188	windowp->data = 0;
	189	if (debug_windows)
	190	fprintf (stderr, "\t\tmmap failed!\n");
	191	goto free_and_fail;
	192	}
	193	if (debug_windows)
	194	fprintf (stderr, "\n\tmapped %ld at %p, offset is %ld\n",
	195	(long) real_size, i->data, (long) offset2);
	196	i->size = real_size;
	197	windowp->data = (bfd_byte *) i->data + offset2;
	198	windowp->size = size;
	199	i->mapped = 1;
	200	i->refcount = 1;
	201	windowp->i = i;
	202	return TRUE;
	203	}
	204	else if (debug_windows)
	205	{
	206	if (ok_to_map)
	207	fprintf (stderr, _("not mapping: data=%lx mapped=%d\n"),
	208	(unsigned long) i->data, (int) i->mapped);
	209	else
	210	fprintf (stderr, _("not mapping: env var not set\n"));
	211	}
	212	#else
	213	ok_to_map = 0;
	214	#endif
	215
	216	#ifdef HAVE_MPROTECT
	217	if (!writable)
	218	{
	219	size_to_alloc += pagesize - 1;
	220	size_to_alloc -= size_to_alloc % pagesize;
	221	}
	222	#endif
	223	if (debug_windows)
	224	fprintf (stderr, "\n\t%s(%6ld)",
	225	i->data ? "realloc" : " malloc", (long) size_to_alloc);
	226	i->data = bfd_realloc_or_free (i->data, size_to_alloc);
	227	if (debug_windows)
	228	fprintf (stderr, "\t-> %p\n", i->data);
	229	if (i->data == NULL)
	230	{
	231	if (size_to_alloc == 0)
	232	{
	233	windowp->i = i;
	234	return TRUE;
	235	}
	236	goto free_and_fail;
	237	}
	238	i->refcount = 1;
	239	if (bfd_seek (abfd, offset, SEEK_SET) != 0)
	240	goto free_and_fail;
	241	i->size = bfd_bread (i->data, size, abfd);
	242	if (i->size != size)
	243	goto free_and_fail;
	244	i->mapped = 0;
	245	#ifdef HAVE_MPROTECT
	246	if (!writable)
	247	{
	248	if (debug_windows)
	249	fprintf (stderr, "\tmprotect (%p, %ld, PROT_READ)\n", i->data,
	250	(long) i->size);
	251	mprotect (i->data, i->size, PROT_READ);
	252	}
	253	#endif
	254	windowp->data = i->data;
	255	windowp->size = i->size;
	256	windowp->i = i;
	257	return TRUE;
	258
	259	free_and_fail:
	260	/* We have a bfd_window_internal, but an error occurred. Free it. */
	261	free (i);
	262	return FALSE;
	263	}
	264
	265	#endif /* USE_MMAP */