gas/config/obj-aout.c

   1 /* a.out object file format
   2    Copyright (C) 1989-2023 Free Software Foundation, Inc.
   3
   4    This file is part of GAS, the GNU Assembler.
   5
   6    GAS is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as
   8    published by the Free Software Foundation; either version 3,
   9    or (at your option) any later version.
  10
  11    GAS is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  14    the GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GAS; see the file COPYING.  If not, write to the Free
  18    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  19    02110-1301, USA.  */
  20
  21 #define OBJ_HEADER "obj-aout.h"
  22
  23 #include "as.h"
  24 #undef NO_RELOC
  25 #include "aout/aout64.h"
  26
  27 void
  28 obj_aout_frob_symbol (symbolS *sym, int *punt ATTRIBUTE_UNUSED)
  29 {
  30   flagword flags;
  31   asection *sec;
  32   int type;
  33
  34   flags = symbol_get_bfdsym (sym)->flags;
  35   type = aout_symbol (symbol_get_bfdsym (sym))->type;
  36   sec = S_GET_SEGMENT (sym);
  37
  38   /* Only frob simple symbols this way right now.  */
  39   if (! (type & ~ (N_TYPE | N_EXT)))
  40     {
  41       if (type == (N_UNDF | N_EXT)
  42           && sec == bfd_abs_section_ptr)
  43         {
  44           sec = bfd_und_section_ptr;
  45           S_SET_SEGMENT (sym, sec);
  46         }
  47
  48       if ((type & N_TYPE) != N_INDR
  49           && (type & N_TYPE) != N_SETA
  50           && (type & N_TYPE) != N_SETT
  51           && (type & N_TYPE) != N_SETD
  52           && (type & N_TYPE) != N_SETB
  53           && type != N_WARNING
  54           && (sec == bfd_abs_section_ptr
  55               || sec == bfd_und_section_ptr))
  56         return;
  57       if (flags & BSF_EXPORT)
  58         type |= N_EXT;
  59
  60       switch (type & N_TYPE)
  61         {
  62         case N_SETA:
  63         case N_SETT:
  64         case N_SETD:
  65         case N_SETB:
  66           /* Set the debugging flag for constructor symbols so that
  67              BFD leaves them alone.  */
  68           symbol_get_bfdsym (sym)->flags |= BSF_DEBUGGING;
  69
  70           /* You can't put a common symbol in a set.  The way a set
  71              element works is that the symbol has a definition and a
  72              name, and the linker adds the definition to the set of
  73              that name.  That does not work for a common symbol,
  74              because the linker can't tell which common symbol the
  75              user means.  FIXME: Using as_bad here may be
  76              inappropriate, since the user may want to force a
  77              particular type without regard to the semantics of sets;
  78              on the other hand, we certainly don't want anybody to be
  79              mislead into thinking that their code will work.  */
  80           if (S_IS_COMMON (sym))
  81             as_bad (_("Attempt to put a common symbol into set %s"),
  82                     S_GET_NAME (sym));
  83           /* Similarly, you can't put an undefined symbol in a set.  */
  84           else if (! S_IS_DEFINED (sym))
  85             as_bad (_("Attempt to put an undefined symbol into set %s"),
  86                     S_GET_NAME (sym));
  87
  88           break;
  89         case N_INDR:
  90           /* Put indirect symbols in the indirect section.  */
  91           S_SET_SEGMENT (sym, bfd_ind_section_ptr);
  92           symbol_get_bfdsym (sym)->flags |= BSF_INDIRECT;
  93           if (type & N_EXT)
  94             {
  95               symbol_get_bfdsym (sym)->flags |= BSF_EXPORT;
  96               symbol_get_bfdsym (sym)->flags &=~ BSF_LOCAL;
  97             }
  98           break;
  99         case N_WARNING:
 100           /* Mark warning symbols.  */
 101           symbol_get_bfdsym (sym)->flags |= BSF_WARNING;
 102           break;
 103         }
 104     }
 105   else
 106     symbol_get_bfdsym (sym)->flags |= BSF_DEBUGGING;
 107
 108   aout_symbol (symbol_get_bfdsym (sym))->type = type;
 109
 110   /* Double check weak symbols.  */
 111   if (S_IS_WEAK (sym) && S_IS_COMMON (sym))
 112     as_bad (_("Symbol `%s' can not be both weak and common"),
 113             S_GET_NAME (sym));
 114 }
 115
 116 /* Relocation processing may require knowing the VMAs of the sections.
 117    Writing to a section will cause the BFD back end to compute the
 118    VMAs.  This function also ensures that file size is large enough
 119    to cover a_text and a_data should text or data be the last section
 120    in the file.  */
 121
 122 void
 123 obj_aout_frob_file_before_fix (void)
 124 {
 125   asection *sec;
 126   bfd_vma *sizep = NULL;
 127   if ((sec = data_section)->size != 0)
 128     sizep = &exec_hdr (stdoutput)->a_data;
 129   else if ((sec = text_section)->size != 0)
 130     sizep = &exec_hdr (stdoutput)->a_text;
 131   if (sizep)
 132     {
 133       bfd_size_type size = sec->size;
 134       bfd_byte b = 0;
 135
 136       gas_assert (bfd_set_section_contents (stdoutput, sec, &b, size - 1, 1));
 137
 138       /* We don't know the aligned size until after VMAs and sizes are
 139          set on the bfd_set_section_contents call.  If that size is
 140          larger than the section then write again to ensure the file
 141          contents extend to cover the aligned size.  */
 142       if (*sizep > size)
 143         {
 144           file_ptr pos = sec->filepos + *sizep;
 145
 146           gas_assert (bfd_seek (stdoutput, pos - 1, SEEK_SET) == 0
 147                       && bfd_write (&b, 1, stdoutput) == 1);
 148         }
 149     }
 150 }
 151
 152 static void
 153 obj_aout_line (int ignore ATTRIBUTE_UNUSED)
 154 {
 155   /* Assume delimiter is part of expression.
 156      BSD4.2 as fails with delightful bug, so we
 157      are not being incompatible here.  */
 158   new_logical_line ((char *) NULL, (int) (get_absolute_expression ()));
 159   demand_empty_rest_of_line ();
 160 }
 161
 162 /* Handle .weak.  This is a GNU extension.  */
 163
 164 static void
 165 obj_aout_weak (int ignore ATTRIBUTE_UNUSED)
 166 {
 167   char *name;
 168   int c;
 169   symbolS *symbolP;
 170
 171   do
 172     {
 173       c = get_symbol_name (&name);
 174       symbolP = symbol_find_or_make (name);
 175       (void) restore_line_pointer (c);
 176       SKIP_WHITESPACE ();
 177       S_SET_WEAK (symbolP);
 178       if (c == ',')
 179         {
 180           input_line_pointer++;
 181           SKIP_WHITESPACE ();
 182           if (*input_line_pointer == '\n')
 183             c = '\n';
 184         }
 185     }
 186   while (c == ',');
 187   demand_empty_rest_of_line ();
 188 }
 189
 190 /* Handle .type.  On {Net,Open}BSD, this is used to set the n_other field,
 191    which is then apparently used when doing dynamic linking.  Older
 192    versions of gas ignored the .type pseudo-op, so we also ignore it if
 193    we can't parse it.  */
 194
 195 static void
 196 obj_aout_type (int ignore ATTRIBUTE_UNUSED)
 197 {
 198   char *name;
 199   int c;
 200   symbolS *sym;
 201
 202   c = get_symbol_name (&name);
 203   sym = symbol_find_or_make (name);
 204   (void) restore_line_pointer (c);
 205   SKIP_WHITESPACE ();
 206   if (*input_line_pointer == ',')
 207     {
 208       ++input_line_pointer;
 209       SKIP_WHITESPACE ();
 210       if (*input_line_pointer == '@')
 211         {
 212           ++input_line_pointer;
 213           if (startswith (input_line_pointer, "object"))
 214             S_SET_OTHER (sym, 1);
 215           else if (startswith (input_line_pointer, "function"))
 216             S_SET_OTHER (sym, 2);
 217         }
 218     }
 219
 220   /* Ignore everything else on the line.  */
 221   s_ignore (0);
 222 }
 223
 224 /* Support for an AOUT emulation.  */
 225
 226 static void
 227 aout_pop_insert (void)
 228 {
 229   pop_insert (aout_pseudo_table);
 230 }
 231
 232 static int
 233 obj_aout_s_get_other (symbolS *sym)
 234 {
 235   return aout_symbol (symbol_get_bfdsym (sym))->other;
 236 }
 237
 238 static void
 239 obj_aout_s_set_other (symbolS *sym, int o)
 240 {
 241   aout_symbol (symbol_get_bfdsym (sym))->other = o;
 242 }
 243
 244 static int
 245 obj_aout_sec_sym_ok_for_reloc (asection *sec ATTRIBUTE_UNUSED)
 246 {
 247   return obj_sec_sym_ok_for_reloc (sec);
 248 }
 249
 250 static void
 251 obj_aout_process_stab (int w,
 252                        const char *s,
 253                        int t,
 254                        int o,
 255                        int d)
 256 {
 257   aout_process_stab (w, s, t, o, d);
 258 }
 259
 260 static int
 261 obj_aout_s_get_desc (symbolS *sym)
 262 {
 263   return aout_symbol (symbol_get_bfdsym (sym))->desc;
 264 }
 265
 266 static void
 267 obj_aout_s_set_desc (symbolS *sym, int d)
 268 {
 269   aout_symbol (symbol_get_bfdsym (sym))->desc = d;
 270 }
 271
 272 static int
 273 obj_aout_s_get_type (symbolS *sym)
 274 {
 275   return aout_symbol (symbol_get_bfdsym (sym))->type;
 276 }
 277
 278 static void
 279 obj_aout_s_set_type (symbolS *sym, int t)
 280 {
 281   aout_symbol (symbol_get_bfdsym (sym))->type = t;
 282 }
 283
 284 static int
 285 obj_aout_separate_stab_sections (void)
 286 {
 287   return 0;
 288 }
 289
 290 /* When changed, make sure these table entries match the single-format
 291    definitions in obj-aout.h.  */
 292
 293 const struct format_ops aout_format_ops =
 294 {
 295   bfd_target_aout_flavour,
 296   1,    /* dfl_leading_underscore.  */
 297   0,    /* emit_section_symbols.  */
 298   0,    /* begin.  */
 299   0,    /* end.  */
 300   0,    /* app_file.  */
 301   obj_aout_frob_symbol,
 302   0,    /* frob_file.  */
 303   0,    /* frob_file_before_adjust.  */
 304   obj_aout_frob_file_before_fix,
 305   0,    /* frob_file_after_relocs.  */
 306   0,    /* s_get_size.  */
 307   0,    /* s_set_size.  */
 308   0,    /* s_get_align.  */
 309   0,    /* s_set_align.  */
 310   obj_aout_s_get_other,
 311   obj_aout_s_set_other,
 312   obj_aout_s_get_desc,
 313   obj_aout_s_set_desc,
 314   obj_aout_s_get_type,
 315   obj_aout_s_set_type,
 316   0,    /* copy_symbol_attributes.  */
 317   0,    /* generate_asm_lineno.  */
 318   obj_aout_process_stab,
 319   obj_aout_separate_stab_sections,
 320   0,    /* init_stab_section.  */
 321   obj_aout_sec_sym_ok_for_reloc,
 322   aout_pop_insert,
 323   0,    /* ecoff_set_ext.  */
 324   0,    /* read_begin_hook.  */
 325   0,    /* symbol_new_hook.  */
 326   0,    /* symbol_clone_hook.  */
 327   0     /* adjust_symtab.  */
 328 };
 329
 330 const pseudo_typeS aout_pseudo_table[] =
 331 {
 332   {"line", obj_aout_line, 0},   /* Source code line number.  */
 333   {"ln", obj_aout_line, 0},     /* COFF line number that we use anyway.  */
 334
 335   {"weak", obj_aout_weak, 0},   /* Mark symbol as weak.  */
 336
 337   {"type", obj_aout_type, 0},
 338
 339   /* coff debug pseudos (ignored) */
 340   {"def", s_ignore, 0},
 341   {"dim", s_ignore, 0},
 342   {"endef", s_ignore, 0},
 343   {"ident", s_ignore, 0},
 344   {"line", s_ignore, 0},
 345   {"ln", s_ignore, 0},
 346   {"scl", s_ignore, 0},
 347   {"size", s_ignore, 0},
 348   {"tag", s_ignore, 0},
 349   {"val", s_ignore, 0},
 350   {"version", s_ignore, 0},
 351
 352   {"optim", s_ignore, 0},       /* For sun386i cc (?).  */
 353
 354   /* other stuff */
 355   {"ABORT", s_abort, 0},
 356
 357   {NULL, NULL, 0}
 358 };