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_bwrite (&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 (segT seg ATTRIBUTE_UNUSED,
252 int w,
253 const char *s,
254 int t,
255 int o,
256 int d)
257 {
258 aout_process_stab (w, s, t, o, d);
259 }
260
261 static int
262 obj_aout_s_get_desc (symbolS *sym)
263 {
264 return aout_symbol (symbol_get_bfdsym (sym))->desc;
265 }
266
267 static void
268 obj_aout_s_set_desc (symbolS *sym, int d)
269 {
270 aout_symbol (symbol_get_bfdsym (sym))->desc = d;
271 }
272
273 static int
274 obj_aout_s_get_type (symbolS *sym)
275 {
276 return aout_symbol (symbol_get_bfdsym (sym))->type;
277 }
278
279 static void
280 obj_aout_s_set_type (symbolS *sym, int t)
281 {
282 aout_symbol (symbol_get_bfdsym (sym))->type = t;
283 }
284
285 static int
286 obj_aout_separate_stab_sections (void)
287 {
288 return 0;
289 }
290
291 /* When changed, make sure these table entries match the single-format
292 definitions in obj-aout.h. */
293
294 const struct format_ops aout_format_ops =
295 {
296 bfd_target_aout_flavour,
297 1, /* dfl_leading_underscore. */
298 0, /* emit_section_symbols. */
299 0, /* begin. */
300 0, /* end. */
301 0, /* app_file. */
302 obj_aout_frob_symbol,
303 0, /* frob_file. */
304 0, /* frob_file_before_adjust. */
305 obj_aout_frob_file_before_fix,
306 0, /* frob_file_after_relocs. */
307 0, /* s_get_size. */
308 0, /* s_set_size. */
309 0, /* s_get_align. */
310 0, /* s_set_align. */
311 obj_aout_s_get_other,
312 obj_aout_s_set_other,
313 obj_aout_s_get_desc,
314 obj_aout_s_set_desc,
315 obj_aout_s_get_type,
316 obj_aout_s_set_type,
317 0, /* copy_symbol_attributes. */
318 0, /* generate_asm_lineno. */
319 obj_aout_process_stab,
320 obj_aout_separate_stab_sections,
321 0, /* init_stab_section. */
322 obj_aout_sec_sym_ok_for_reloc,
323 aout_pop_insert,
324 0, /* ecoff_set_ext. */
325 0, /* read_begin_hook. */
326 0, /* symbol_new_hook. */
327 0, /* symbol_clone_hook. */
328 0 /* adjust_symtab. */
329 };
330
331 const pseudo_typeS aout_pseudo_table[] =
332 {
333 {"line", obj_aout_line, 0}, /* Source code line number. */
334 {"ln", obj_aout_line, 0}, /* COFF line number that we use anyway. */
335
336 {"weak", obj_aout_weak, 0}, /* Mark symbol as weak. */
337
338 {"type", obj_aout_type, 0},
339
340 /* coff debug pseudos (ignored) */
341 {"def", s_ignore, 0},
342 {"dim", s_ignore, 0},
343 {"endef", s_ignore, 0},
344 {"ident", s_ignore, 0},
345 {"line", s_ignore, 0},
346 {"ln", s_ignore, 0},
347 {"scl", s_ignore, 0},
348 {"size", s_ignore, 0},
349 {"tag", s_ignore, 0},
350 {"val", s_ignore, 0},
351 {"version", s_ignore, 0},
352
353 {"optim", s_ignore, 0}, /* For sun386i cc (?). */
354
355 /* other stuff */
356 {"ABORT", s_abort, 0},
357
358 {NULL, NULL, 0}
359 };