libasm/asm_align.c

/* Align section.
   Copyright (C) 2002, 2005 Red Hat, Inc.
   This file is part of elfutils.
   Written by Ulrich Drepper <drepper@redhat.com>, 2002.

   This file is free software; you can redistribute it and/or modify
   it under the terms of either

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at
       your option) any later version

   or

     * 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

   or both in parallel, as here.

   elfutils 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 copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see <http://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <inttypes.h>
#include <stdlib.h>

#include <libasmP.h>
#include <system.h>


int
asm_align (AsmScn_t *asmscn, GElf_Word value)
{
  if (asmscn == NULL)
    /* An earlier error.  */
    return -1;

      /* The alignment value must be a power of two.  */
  if (unlikely (! powerof2 (value)))
    {
      __libasm_seterrno (ASM_E_INVALID);
      return -1;
    }

  if (unlikely (asmscn->ctx->textp))
    {
      fprintf (asmscn->ctx->out.file, "\t.align %" PRId32 ", ",
	       (int32_t) value);
      if (asmscn->pattern->len == 1)
	fprintf (asmscn->ctx->out.file, "%02hhx\n", asmscn->pattern->bytes[0]);
      else
	{
	  fputc_unlocked ('"', asmscn->ctx->out.file);

	  for (size_t cnt = 0; cnt < asmscn->pattern->len; ++cnt)
	    fprintf (asmscn->ctx->out.file, "\\x%02hhx",
		     asmscn->pattern->bytes[cnt]);

	  fputs_unlocked ("\"\n", asmscn->ctx->out.file);
	}
      return 0;
    }

  rwlock_wrlock (asmscn->ctx->lock);

  int result = 0;

  /* Fillbytes necessary?  */
  if ((asmscn->offset & (value - 1)) != 0)
    {
      /* Add fillbytes.  */
      size_t cnt = value - (asmscn->offset & (value - 1));

      /* Ensure there is enough room to add the fill bytes.  */
      result = __libasm_ensure_section_space (asmscn, cnt);
      if (result != 0)
	goto out;

      /* Fill in the bytes.  We align the pattern according to the
	 current offset.  */
      size_t byteptr = asmscn->offset % asmscn->pattern->len;

      /* Update the total size.  */
      asmscn->offset += cnt;

      do
	{
	  asmscn->content->data[asmscn->content->len++]
	    = asmscn->pattern->bytes[byteptr++];

	  if (byteptr == asmscn->pattern->len)
	    byteptr = 0;
	}
      while (--cnt > 0);
    }

  /* Remember the maximum alignment for this subsection.  */
  if (asmscn->max_align < value)
    {
      asmscn->max_align = value;

      /* Update the parent as well (if it exists).  */
      if (asmscn->subsection_id != 0)
	{
	  rwlock_wrlock (asmscn->data.up->ctx->lock);

	  if (asmscn->data.up->max_align < value)
	    asmscn->data.up->max_align = value;

	  rwlock_unlock (asmscn->data.up->ctx->lock);
	}
    }

 out:
  rwlock_unlock (asmscn->ctx->lock);

  return result;
}


/* Ensure there are at least LEN bytes available in the output buffer
   for ASMSCN.  */
int
internal_function
__libasm_ensure_section_space (AsmScn_t *asmscn, size_t len)
{
  /* The blocks with the section content are kept in a circular
     single-linked list.  */
  size_t size;

  if (asmscn->content == NULL)
    {
      /* This is the first block.  */
      size = MAX (2 * len, 960);

      asmscn->content = calloc (1, sizeof (struct AsmData) + size);
      if (asmscn->content == NULL)
	return -1;

      asmscn->content->next = asmscn->content;
    }
  else
    {
      struct AsmData *newp;

      if (asmscn->content->maxlen - asmscn->content->len >= len)
	/* Nothing to do, there is enough space.  */
	return 0;

      size = MAX (2 *len, MIN (32768, 2 * asmscn->offset));

      newp = calloc (1, sizeof (struct AsmData) + size);
      if (newp == NULL)
	return -1;

      newp->next = asmscn->content->next;
      asmscn->content = asmscn->content->next = newp;
    }

  asmscn->content->len = 0;
  asmscn->content->maxlen = size;

  return 0;
}