libasm/asm_newcomsym.c

/* Create new COMMON symbol.
   Copyright (C) 2002, 2016 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 <stdio.h>
#include <stdlib.h>
#include <string.h>

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


/* Object for special COMMON section.  */
static const AsmScn_t __libasm_com_scn =
  {
    .data = {
      .main = {
	.scn = ASM_COM_SCN
      }
    }
  };


AsmSym_t *
asm_newcomsym (AsmCtx_t *ctx, const char *name, GElf_Xword size,
	       GElf_Addr align)
{
  AsmSym_t *result;

  if (ctx == NULL)
    /* Something went wrong before.  */
    return NULL;

  /* Common symbols are public.  Therefore the user must provide a
     name.  */
  if (name == NULL)
    {
      __libasm_seterrno (ASM_E_INVALID);
      return NULL;
    }

  rwlock_wrlock (ctx->lock);

  result = malloc (sizeof (AsmSym_t));
  if (result == NULL)
    return NULL;

  result->scn = (AsmScn_t *) &__libasm_com_scn;
  result->size = size;
  /* XXX Do we have to allow a different type?  */
  result->type = STT_OBJECT;
  /* XXX Do we have to allow a different binding?  */
  result->binding = STB_GLOBAL;
  result->symidx = 0;
  result->strent = dwelf_strtab_add (ctx->symbol_strtab, name);

  /* The value of a COM symbol is the alignment.  Since there are no
     subsection and the initial offset of the section is 0 we can get
     the alignment recorded by storing it into the offset field.  */
  result->offset = align;

  if (unlikely (ctx->textp))
    fprintf (ctx->out.file, "\t.comm %s, %" PRIuMAX ", %" PRIuMAX "\n",
	     name, (uintmax_t) size, (uintmax_t) align);
  else
    {
      /* Put the symbol in the hash table so that we can later find it.  */
      if (asm_symbol_tab_insert (&ctx->symbol_tab, elf_hash (name), result)
	  != 0)
	{
	  /* The symbol already exists.  */
	  __libasm_seterrno (ASM_E_DUPLSYM);
	  free (result);
	  result = NULL;
	}
      else if (name != NULL && asm_emit_symbol_p (name))
	/* Only count non-private symbols.  */
	++ctx->nsymbol_tab;
    }

  rwlock_unlock (ctx->lock);

  return result;
}