libasm/asm_begin.c

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

   Red Hat elfutils 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; version 2 of the License.

   Red Hat 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 a copy of the GNU General Public License along
   with Red Hat elfutils; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

   Red Hat elfutils is an included package of the Open Invention Network.
   An included package of the Open Invention Network is a package for which
   Open Invention Network licensees cross-license their patents.  No patent
   license is granted, either expressly or impliedly, by designation as an
   included package.  Should you wish to participate in the Open Invention
   Network licensing program, please visit www.openinventionnetwork.com
   <http://www.openinventionnetwork.com>.  */

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

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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


static AsmCtx_t *
prepare_text_output (AsmCtx_t *result)
{
  if (result->fd == -1)
    result->out.file = stdout;
  else
    {
      result->out.file = fdopen (result->fd, "a");
      if (result->out.file == NULL)
	{
	  close (result->fd);
	  free (result);
	  result = NULL;
	}

      __fsetlocking (result->out.file, FSETLOCKING_BYCALLER);
    }

  return result;
}


static AsmCtx_t *
prepare_binary_output (AsmCtx_t *result, Ebl *ebl)
{
  GElf_Ehdr *ehdr;
  GElf_Ehdr ehdr_mem;

  /* Create the ELF descriptor for the file.  */
  result->out.elf = elf_begin (result->fd, ELF_C_WRITE_MMAP, NULL);
  if (result->out.elf == NULL)
    {
    err_libelf:
      unlink (result->tmp_fname);
      close (result->fd);
      free (result);
      __libasm_seterrno (ASM_E_LIBELF);
      return NULL;
    }

  /* Create the ELF header for the output file.  */
  int class = ebl_get_elfclass (ebl);
  if (gelf_newehdr (result->out.elf, class) == 0)
    goto err_libelf;

  ehdr = gelf_getehdr (result->out.elf, &ehdr_mem);
  /* If this failed we are in trouble.  */
  assert (ehdr != NULL);

  /* We create an object file.  */
  ehdr->e_type = ET_REL;
  /* Set the ELF version.  */
  ehdr->e_version = EV_CURRENT;

  /* Use the machine, class, and endianess values from the Ebl descriptor.  */
  ehdr->e_machine = ebl_get_elfmachine (ebl);
  ehdr->e_ident[EI_CLASS] = class;
  ehdr->e_ident[EI_DATA] = ebl_get_elfdata (ebl);

  memcpy (&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG);

  /* Write the ELF header information back.  */
  (void) gelf_update_ehdr (result->out.elf, ehdr);

  /* No section so far.  */
  result->section_list = NULL;

  /* Initialize the hash table.  */
  asm_symbol_tab_init (&result->symbol_tab, 67);
  result->nsymbol_tab = 0;
  /* And the string tables.  */
  result->section_strtab = ebl_strtabinit (true);
  result->symbol_strtab = ebl_strtabinit (true);

  /* We have no section groups so far.  */
  result->groups = NULL;
  result->ngroups = 0;

  return result;
}


AsmCtx_t *
asm_begin (fname, ebl, textp)
     const char *fname;
     Ebl *ebl;
     bool textp;
{
  if (fname == NULL && ! textp)
    return NULL;

  size_t fname_len = fname != NULL ? strlen (fname) : 0;

  /* Create the file descriptor.  We do not generate the output file
     right away.  Instead we create a temporary file in the same
     directory which, if everything goes alright, will replace a
     possibly existing file with the given name.  */
  AsmCtx_t *result
    = (AsmCtx_t *) malloc (sizeof (AsmCtx_t) + 2 * fname_len + 9);
  if (result == NULL)
    return NULL;

      /* Initialize the lock.  */
      rwlock_init (result->lock);

  if (fname != NULL)
    {
      /* Create the name of the temporary file.  */
      result->fname = stpcpy (mempcpy (result->tmp_fname, fname, fname_len),
			      ".XXXXXX") + 1;
      memcpy (result->fname, fname, fname_len + 1);

      /* Create the temporary file.  */
      result->fd = mkstemp (result->tmp_fname);
      if (result->fd == -1)
	{
	  int save_errno = errno;
	  free (result);
	  __libasm_seterrno (ASM_E_CANNOT_CREATE);
	  errno = save_errno;
	  return NULL;
	}
    }
  else
    result->fd = -1;

  /* Initialize the counter for temporary symbols.  */
  result->tempsym_count = 0;

  /* Now we differentiate between textual and binary output.   */
  result->textp = textp;
  if (textp)
    result = prepare_text_output (result);
  else
    result = prepare_binary_output (result, ebl);

  return result;
}