gas/config/obj-aout.c

/* a.out object file format
   Copyright (C) 1989-2021 Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS 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,
   or (at your option) any later version.

   GAS 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 GAS; see the file COPYING.  If not, write to the Free
   Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
   02110-1301, USA.  */

#define OBJ_HEADER "obj-aout.h"

#include "as.h"
#undef NO_RELOC
#include "aout/aout64.h"

void
obj_aout_frob_symbol (symbolS *sym, int *punt ATTRIBUTE_UNUSED)
{
  flagword flags;
  asection *sec;
  int type;

  flags = symbol_get_bfdsym (sym)->flags;
  type = aout_symbol (symbol_get_bfdsym (sym))->type;
  sec = S_GET_SEGMENT (sym);

  /* Only frob simple symbols this way right now.  */
  if (! (type & ~ (N_TYPE | N_EXT)))
    {
      if (type == (N_UNDF | N_EXT)
	  && sec == bfd_abs_section_ptr)
	{
	  sec = bfd_und_section_ptr;
	  S_SET_SEGMENT (sym, sec);
	}

      if ((type & N_TYPE) != N_INDR
	  && (type & N_TYPE) != N_SETA
	  && (type & N_TYPE) != N_SETT
	  && (type & N_TYPE) != N_SETD
	  && (type & N_TYPE) != N_SETB
	  && type != N_WARNING
	  && (sec == bfd_abs_section_ptr
	      || sec == bfd_und_section_ptr))
	return;
      if (flags & BSF_EXPORT)
	type |= N_EXT;

      switch (type & N_TYPE)
	{
	case N_SETA:
	case N_SETT:
	case N_SETD:
	case N_SETB:
	  /* Set the debugging flag for constructor symbols so that
	     BFD leaves them alone.  */
	  symbol_get_bfdsym (sym)->flags |= BSF_DEBUGGING;

	  /* You can't put a common symbol in a set.  The way a set
	     element works is that the symbol has a definition and a
	     name, and the linker adds the definition to the set of
	     that name.  That does not work for a common symbol,
	     because the linker can't tell which common symbol the
	     user means.  FIXME: Using as_bad here may be
	     inappropriate, since the user may want to force a
	     particular type without regard to the semantics of sets;
	     on the other hand, we certainly don't want anybody to be
	     mislead into thinking that their code will work.  */
	  if (S_IS_COMMON (sym))
	    as_bad (_("Attempt to put a common symbol into set %s"),
		    S_GET_NAME (sym));
	  /* Similarly, you can't put an undefined symbol in a set.  */
	  else if (! S_IS_DEFINED (sym))
	    as_bad (_("Attempt to put an undefined symbol into set %s"),
		    S_GET_NAME (sym));

	  break;
	case N_INDR:
	  /* Put indirect symbols in the indirect section.  */
	  S_SET_SEGMENT (sym, bfd_ind_section_ptr);
	  symbol_get_bfdsym (sym)->flags |= BSF_INDIRECT;
	  if (type & N_EXT)
	    {
	      symbol_get_bfdsym (sym)->flags |= BSF_EXPORT;
	      symbol_get_bfdsym (sym)->flags &=~ BSF_LOCAL;
	    }
	  break;
	case N_WARNING:
	  /* Mark warning symbols.  */
	  symbol_get_bfdsym (sym)->flags |= BSF_WARNING;
	  break;
	}
    }
  else
    symbol_get_bfdsym (sym)->flags |= BSF_DEBUGGING;

  aout_symbol (symbol_get_bfdsym (sym))->type = type;

  /* Double check weak symbols.  */
  if (S_IS_WEAK (sym) && S_IS_COMMON (sym))
    as_bad (_("Symbol `%s' can not be both weak and common"),
	    S_GET_NAME (sym));
}

/* Relocation processing may require knowing the VMAs of the sections.
   Writing to a section will cause the BFD back end to compute the
   VMAs.  This function also ensures that file size is large enough
   to cover a_text and a_data should text or data be the last section
   in the file.  */

void
obj_aout_frob_file_before_fix (void)
{
  asection *sec;
  bfd_vma *sizep = NULL;
  if ((sec = data_section)->size != 0)
    sizep = &exec_hdr (stdoutput)->a_data;
  else if ((sec = text_section)->size != 0)
    sizep = &exec_hdr (stdoutput)->a_text;
  if (sizep)
    {
      bfd_size_type size = sec->size;
      bfd_byte b = 0;

      gas_assert (bfd_set_section_contents (stdoutput, sec, &b, size - 1, 1));

      /* We don't know the aligned size until after VMAs and sizes are
	 set on the bfd_set_section_contents call.  If that size is
	 larger than the section then write again to ensure the file
	 contents extend to cover the aligned size.  */
      if (*sizep > size)
	{
	  file_ptr pos = sec->filepos + *sizep;

	  gas_assert (bfd_seek (stdoutput, pos - 1, SEEK_SET) == 0
		      && bfd_bwrite (&b, 1, stdoutput) == 1);
	}
    }
}

static void
obj_aout_line (int ignore ATTRIBUTE_UNUSED)
{
  /* Assume delimiter is part of expression.
     BSD4.2 as fails with delightful bug, so we
     are not being incompatible here.  */
  new_logical_line ((char *) NULL, (int) (get_absolute_expression ()));
  demand_empty_rest_of_line ();
}

/* Handle .weak.  This is a GNU extension.  */

static void
obj_aout_weak (int ignore ATTRIBUTE_UNUSED)
{
  char *name;
  int c;
  symbolS *symbolP;

  do
    {
      c = get_symbol_name (&name);
      symbolP = symbol_find_or_make (name);
      (void) restore_line_pointer (c);
      SKIP_WHITESPACE ();
      S_SET_WEAK (symbolP);
      if (c == ',')
	{
	  input_line_pointer++;
	  SKIP_WHITESPACE ();
	  if (*input_line_pointer == '\n')
	    c = '\n';
	}
    }
  while (c == ',');
  demand_empty_rest_of_line ();
}

/* Handle .type.  On {Net,Open}BSD, this is used to set the n_other field,
   which is then apparently used when doing dynamic linking.  Older
   versions of gas ignored the .type pseudo-op, so we also ignore it if
   we can't parse it.  */

static void
obj_aout_type (int ignore ATTRIBUTE_UNUSED)
{
  char *name;
  int c;
  symbolS *sym;

  c = get_symbol_name (&name);
  sym = symbol_find_or_make (name);
  (void) restore_line_pointer (c);
  SKIP_WHITESPACE ();
  if (*input_line_pointer == ',')
    {
      ++input_line_pointer;
      SKIP_WHITESPACE ();
      if (*input_line_pointer == '@')
	{
	  ++input_line_pointer;
	  if (startswith (input_line_pointer, "object"))
	    S_SET_OTHER (sym, 1);
	  else if (startswith (input_line_pointer, "function"))
	    S_SET_OTHER (sym, 2);
	}
    }

  /* Ignore everything else on the line.  */
  s_ignore (0);
}

/* Support for an AOUT emulation.  */

static void
aout_pop_insert (void)
{
  pop_insert (aout_pseudo_table);
}

static int
obj_aout_s_get_other (symbolS *sym)
{
  return aout_symbol (symbol_get_bfdsym (sym))->other;
}

static void
obj_aout_s_set_other (symbolS *sym, int o)
{
  aout_symbol (symbol_get_bfdsym (sym))->other = o;
}

static int
obj_aout_sec_sym_ok_for_reloc (asection *sec ATTRIBUTE_UNUSED)
{
  return obj_sec_sym_ok_for_reloc (sec);
}

static void
obj_aout_process_stab (segT seg ATTRIBUTE_UNUSED,
		       int w,
		       const char *s,
		       int t,
		       int o,
		       int d)
{
  aout_process_stab (w, s, t, o, d);
}

static int
obj_aout_s_get_desc (symbolS *sym)
{
  return aout_symbol (symbol_get_bfdsym (sym))->desc;
}

static void
obj_aout_s_set_desc (symbolS *sym, int d)
{
  aout_symbol (symbol_get_bfdsym (sym))->desc = d;
}

static int
obj_aout_s_get_type (symbolS *sym)
{
  return aout_symbol (symbol_get_bfdsym (sym))->type;
}

static void
obj_aout_s_set_type (symbolS *sym, int t)
{
  aout_symbol (symbol_get_bfdsym (sym))->type = t;
}

static int
obj_aout_separate_stab_sections (void)
{
  return 0;
}

/* When changed, make sure these table entries match the single-format
   definitions in obj-aout.h.  */

const struct format_ops aout_format_ops =
{
  bfd_target_aout_flavour,
  1,	/* dfl_leading_underscore.  */
  0,	/* emit_section_symbols.  */
  0,	/* begin.  */
  0,	/* app_file.  */
  obj_aout_frob_symbol,
  0,	/* frob_file.  */
  0,	/* frob_file_before_adjust.  */
  obj_aout_frob_file_before_fix,
  0,	/* frob_file_after_relocs.  */
  0,	/* s_get_size.  */
  0,	/* s_set_size.  */
  0,	/* s_get_align.  */
  0,	/* s_set_align.  */
  obj_aout_s_get_other,
  obj_aout_s_set_other,
  obj_aout_s_get_desc,
  obj_aout_s_set_desc,
  obj_aout_s_get_type,
  obj_aout_s_set_type,
  0,	/* copy_symbol_attributes.  */
  0,	/* generate_asm_lineno.  */
  obj_aout_process_stab,
  obj_aout_separate_stab_sections,
  0,	/* init_stab_section.  */
  obj_aout_sec_sym_ok_for_reloc,
  aout_pop_insert,
  0,	/* ecoff_set_ext.  */
  0,	/* read_begin_hook.  */
  0,	/* symbol_new_hook.  */
  0,	/* symbol_clone_hook.  */
  0	/* adjust_symtab.  */
};

const pseudo_typeS aout_pseudo_table[] =
{
  {"line", obj_aout_line, 0},	/* Source code line number.  */
  {"ln", obj_aout_line, 0},	/* COFF line number that we use anyway.  */

  {"weak", obj_aout_weak, 0},	/* Mark symbol as weak.  */

  {"type", obj_aout_type, 0},

  /* coff debug pseudos (ignored) */
  {"def", s_ignore, 0},
  {"dim", s_ignore, 0},
  {"endef", s_ignore, 0},
  {"ident", s_ignore, 0},
  {"line", s_ignore, 0},
  {"ln", s_ignore, 0},
  {"scl", s_ignore, 0},
  {"size", s_ignore, 0},
  {"tag", s_ignore, 0},
  {"val", s_ignore, 0},
  {"version", s_ignore, 0},

  {"optim", s_ignore, 0},	/* For sun386i cc (?).  */

  /* other stuff */
  {"ABORT", s_abort, 0},

  {NULL, NULL, 0}
};