libiberty/simple-object.c

   1 /* simple-object.c -- simple routines to read and write object files.
   2    Copyright (C) 2010-2017 Free Software Foundation, Inc.
   3    Written by Ian Lance Taylor, Google.
   4
   5 This program is free software; you can redistribute it and/or modify it
   6 under the terms of the GNU General Public License as published by the
   7 Free Software Foundation; either version 2, or (at your option) any
   8 later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, 51 Franklin Street - Fifth Floor,
  18 Boston, MA 02110-1301, USA.  */
  19
  20 #include "config.h"
  21 #include "libiberty.h"
  22 #include "simple-object.h"
  23
  24 #include <errno.h>
  25 #include <fcntl.h>
  26
  27 #ifdef HAVE_STDLIB_H
  28 #include <stdlib.h>
  29 #endif
  30
  31 #ifdef HAVE_STDINT_H
  32 #include <stdint.h>
  33 #endif
  34
  35 #ifdef HAVE_STRING_H
  36 #include <string.h>
  37 #endif
  38
  39 #ifdef HAVE_INTTYPES_H
  40 #include <inttypes.h>
  41 #endif
  42
  43 #ifndef SEEK_SET
  44 #define SEEK_SET 0
  45 #endif
  46
  47 #include "simple-object-common.h"
  48
  49 /* The known object file formats.  */
  50
  51 static const struct simple_object_functions * const format_functions[] =
  52 {
  53   &simple_object_elf_functions,
  54   &simple_object_mach_o_functions,
  55   &simple_object_coff_functions,
  56   &simple_object_xcoff_functions
  57 };
  58
  59 /* Read data from a file using the simple_object error reporting
  60    conventions.  */
  61
  62 int
  63 simple_object_internal_read (int descriptor, off_t offset,
  64                              unsigned char *buffer, size_t size,
  65                              const char **errmsg, int *err)
  66 {
  67   if (lseek (descriptor, offset, SEEK_SET) < 0)
  68     {
  69       *errmsg = "lseek";
  70       *err = errno;
  71       return 0;
  72     }
  73
  74   do
  75     {
  76       ssize_t got = read (descriptor, buffer, size);
  77       if (got == 0)
  78         break;
  79       else if (got > 0)
  80         {
  81           buffer += got;
  82           size -= got;
  83         }
  84       else if (errno != EINTR)
  85         {
  86           *errmsg = "read";
  87           *err = errno;
  88           return 0;
  89         }
  90     }
  91   while (size > 0);
  92
  93   if (size > 0)
  94     {
  95       *errmsg = "file too short";
  96       *err = 0;
  97       return 0;
  98     }
  99
 100   return 1;
 101 }
 102
 103 /* Write data to a file using the simple_object error reporting
 104    conventions.  */
 105
 106 int
 107 simple_object_internal_write (int descriptor, off_t offset,
 108                               const unsigned char *buffer, size_t size,
 109                               const char **errmsg, int *err)
 110 {
 111   if (lseek (descriptor, offset, SEEK_SET) < 0)
 112     {
 113       *errmsg = "lseek";
 114       *err = errno;
 115       return 0;
 116     }
 117
 118   do
 119     {
 120       ssize_t wrote = write (descriptor, buffer, size);
 121       if (wrote == 0)
 122         break;
 123       else if (wrote > 0)
 124         {
 125           buffer += wrote;
 126           size -= wrote;
 127         }
 128       else if (errno != EINTR)
 129         {
 130           *errmsg = "write";
 131           *err = errno;
 132           return 0;
 133         }
 134     }
 135   while (size > 0);
 136
 137   if (size > 0)
 138     {
 139       *errmsg = "short write";
 140       *err = 0;
 141       return 0;
 142     }
 143
 144   return 1;
 145 }
 146
 147 /* Open for read.  */
 148
 149 simple_object_read *
 150 simple_object_start_read (int descriptor, off_t offset,
 151                           const char *segment_name, const char **errmsg,
 152                           int *err)
 153 {
 154   unsigned char header[SIMPLE_OBJECT_MATCH_HEADER_LEN];
 155   size_t len, i;
 156
 157   if (!simple_object_internal_read (descriptor, offset, header,
 158                                     SIMPLE_OBJECT_MATCH_HEADER_LEN,
 159                                     errmsg, err))
 160     return NULL;
 161
 162   len = sizeof (format_functions) / sizeof (format_functions[0]);
 163   for (i = 0; i < len; ++i)
 164     {
 165       void *data;
 166
 167       data = format_functions[i]->match (header, descriptor, offset,
 168                                          segment_name, errmsg, err);
 169       if (data != NULL)
 170         {
 171           simple_object_read *ret;
 172
 173           ret = XNEW (simple_object_read);
 174           ret->descriptor = descriptor;
 175           ret->offset = offset;
 176           ret->functions = format_functions[i];
 177           ret->data = data;
 178           return ret;
 179         }
 180     }
 181
 182   *errmsg = "file not recognized";
 183   *err = 0;
 184   return NULL;
 185 }
 186
 187 /* Find all sections.  */
 188
 189 const char *
 190 simple_object_find_sections (simple_object_read *sobj,
 191                              int (*pfn) (void *, const char *, off_t, off_t),
 192                              void *data,
 193                              int *err)
 194 {
 195   return sobj->functions->find_sections (sobj, pfn, data, err);
 196 }
 197
 198 /* Internal data passed to find_one_section.  */
 199
 200 struct find_one_section_data
 201 {
 202   /* The section we are looking for.  */
 203   const char *name;
 204   /* Where to store the section offset.  */
 205   off_t *offset;
 206   /* Where to store the section length.  */
 207   off_t *length;
 208   /* Set if the name is found.  */
 209   int found;
 210 };
 211
 212 /* Internal function passed to find_sections.  */
 213
 214 static int
 215 find_one_section (void *data, const char *name, off_t offset, off_t length)
 216 {
 217   struct find_one_section_data *fosd = (struct find_one_section_data *) data;
 218
 219   if (strcmp (name, fosd->name) != 0)
 220     return 1;
 221
 222   *fosd->offset = offset;
 223   *fosd->length = length;
 224   fosd->found = 1;
 225
 226   /* Stop iteration.  */
 227   return 0;
 228 }
 229
 230 /* Find a section.  */
 231
 232 int
 233 simple_object_find_section (simple_object_read *sobj, const char *name,
 234                             off_t *offset, off_t *length,
 235                             const char **errmsg, int *err)
 236 {
 237   struct find_one_section_data fosd;
 238
 239   fosd.name = name;
 240   fosd.offset = offset;
 241   fosd.length = length;
 242   fosd.found = 0;
 243
 244   *errmsg = simple_object_find_sections (sobj, find_one_section,
 245                                          (void *) &fosd, err);
 246   if (*errmsg != NULL)
 247     return 0;
 248   if (!fosd.found)
 249     return 0;
 250   return 1;
 251 }
 252
 253 /* Callback to identify and rename LTO debug sections by name.
 254    Returns 1 if NAME is a LTO debug section, 0 if not.  */
 255
 256 static int
 257 handle_lto_debug_sections (const char **name)
 258 {
 259   /* ???  So we can't use .gnu.lto_ prefixed sections as the assembler
 260      complains about bogus section flags.  Which means we need to arrange
 261      for that to be fixed or .gnu.debuglto_ marked as SHF_EXCLUDE (to make
 262      fat lto object tooling work for the fat part).  */
 263   /* ???  For now this handles both .gnu.lto_ and .gnu.debuglto_ prefixed
 264      sections.  */
 265   /* Copy LTO debug sections and rename them to their non-LTO name.  */
 266   if (strncmp (*name, ".gnu.debuglto_", sizeof (".gnu.debuglto_") - 1) == 0)
 267     {
 268       *name = *name + sizeof (".gnu.debuglto_") - 1;
 269       return 1;
 270     }
 271   else if (strncmp (*name, ".gnu.lto_.debug_", sizeof (".gnu.lto_.debug_") -1) == 0)
 272     {
 273       *name = *name + sizeof (".gnu.lto_") - 1;
 274       return 1;
 275     }
 276   /* Copy over .note.GNU-stack section under the same name if present.  */
 277   else if (strcmp (*name, ".note.GNU-stack") == 0)
 278     return 1;
 279   return 0;
 280 }
 281
 282 /* Copy LTO debug sections.  */
 283
 284 const char *
 285 simple_object_copy_lto_debug_sections (simple_object_read *sobj,
 286                                        const char *dest, int *err)
 287 {
 288   const char *errmsg;
 289   simple_object_write *dest_sobj;
 290   simple_object_attributes *attrs;
 291   int outfd;
 292
 293   if (! sobj->functions->copy_lto_debug_sections)
 294     {
 295       *err = EINVAL;
 296       return "simple_object_copy_lto_debug_sections not implemented";
 297     }
 298
 299   attrs = simple_object_fetch_attributes (sobj, &errmsg, err);
 300   if (! attrs)
 301     return errmsg;
 302   dest_sobj = simple_object_start_write (attrs, NULL, &errmsg, err);
 303   simple_object_release_attributes (attrs);
 304   if (! dest_sobj)
 305     return errmsg;
 306
 307   errmsg = sobj->functions->copy_lto_debug_sections (sobj, dest_sobj,
 308                                                      handle_lto_debug_sections,
 309                                                      err);
 310   if (errmsg)
 311     {
 312       simple_object_release_write (dest_sobj);
 313       return errmsg;
 314     }
 315
 316   outfd = creat (dest, 00777);
 317   if (outfd == -1)
 318     {
 319       *err = errno;
 320       simple_object_release_write (dest_sobj);
 321       return "open failed";
 322     }
 323
 324   errmsg = simple_object_write_to_file (dest_sobj, outfd, err);
 325   close (outfd);
 326   if (errmsg)
 327     {
 328       simple_object_release_write (dest_sobj);
 329       return errmsg;
 330     }
 331
 332   simple_object_release_write (dest_sobj);
 333   return NULL;
 334 }
 335
 336 /* Fetch attributes.  */
 337
 338 simple_object_attributes *
 339 simple_object_fetch_attributes (simple_object_read *sobj, const char **errmsg,
 340                                 int *err)
 341 {
 342   void *data;
 343   simple_object_attributes *ret;
 344
 345   data = sobj->functions->fetch_attributes (sobj, errmsg, err);
 346   if (data == NULL)
 347     return NULL;
 348   ret = XNEW (simple_object_attributes);
 349   ret->functions = sobj->functions;
 350   ret->data = data;
 351   return ret;
 352 }
 353
 354 /* Release an simple_object_read.  */
 355
 356 void
 357 simple_object_release_read (simple_object_read *sobj)
 358 {
 359   sobj->functions->release_read (sobj->data);
 360   XDELETE (sobj);
 361 }
 362
 363 /* Merge attributes.  */
 364
 365 const char *
 366 simple_object_attributes_merge (simple_object_attributes *to,
 367                                 simple_object_attributes *from,
 368                                 int *err)
 369 {
 370   if (to->functions != from->functions)
 371     {
 372       *err = 0;
 373       return "different object file format";
 374     }
 375   return to->functions->attributes_merge (to->data, from->data, err);
 376 }
 377
 378 /* Release an attributes structure.  */
 379
 380 void
 381 simple_object_release_attributes (simple_object_attributes *attrs)
 382 {
 383   attrs->functions->release_attributes (attrs->data);
 384   XDELETE (attrs);
 385 }
 386
 387 /* Start creating an object file.  */
 388
 389 simple_object_write *
 390 simple_object_start_write (simple_object_attributes *attrs,
 391                            const char *segment_name, const char **errmsg,
 392                            int *err)
 393 {
 394   void *data;
 395   simple_object_write *ret;
 396
 397   data = attrs->functions->start_write (attrs->data, errmsg, err);
 398   if (data == NULL)
 399     return NULL;
 400   ret = XNEW (simple_object_write);
 401   ret->functions = attrs->functions;
 402   ret->segment_name = segment_name ? xstrdup (segment_name) : NULL;
 403   ret->sections = NULL;
 404   ret->last_section = NULL;
 405   ret->data = data;
 406   return ret;
 407 }
 408
 409 /* Start creating a section.  */
 410
 411 simple_object_write_section *
 412 simple_object_write_create_section (simple_object_write *sobj, const char *name,
 413                                     unsigned int align,
 414                                     const char **errmsg ATTRIBUTE_UNUSED,
 415                                     int *err ATTRIBUTE_UNUSED)
 416 {
 417   simple_object_write_section *ret;
 418
 419   ret = XNEW (simple_object_write_section);
 420   ret->next = NULL;
 421   ret->name = xstrdup (name);
 422   ret->align = align;
 423   ret->buffers = NULL;
 424   ret->last_buffer = NULL;
 425
 426   if (sobj->last_section == NULL)
 427     {
 428       sobj->sections = ret;
 429       sobj->last_section = ret;
 430     }
 431   else
 432     {
 433       sobj->last_section->next = ret;
 434       sobj->last_section = ret;
 435     }
 436
 437   return ret;
 438 }
 439
 440 /* Add data to a section.  */
 441
 442 const char *
 443 simple_object_write_add_data (simple_object_write *sobj ATTRIBUTE_UNUSED,
 444                               simple_object_write_section *section,
 445                               const void *buffer,
 446                               size_t size, int copy,
 447                               int *err ATTRIBUTE_UNUSED)
 448 {
 449   struct simple_object_write_section_buffer *wsb;
 450
 451   wsb = XNEW (struct simple_object_write_section_buffer);
 452   wsb->next = NULL;
 453   wsb->size = size;
 454
 455   if (!copy)
 456     {
 457       wsb->buffer = buffer;
 458       wsb->free_buffer = NULL;
 459     }
 460   else
 461     {
 462       wsb->free_buffer = (void *) XNEWVEC (char, size);
 463       memcpy (wsb->free_buffer, buffer, size);
 464       wsb->buffer = wsb->free_buffer;
 465     }
 466
 467   if (section->last_buffer == NULL)
 468     {
 469       section->buffers = wsb;
 470       section->last_buffer = wsb;
 471     }
 472   else
 473     {
 474       section->last_buffer->next = wsb;
 475       section->last_buffer = wsb;
 476     }
 477
 478   return NULL;
 479 }
 480
 481 /* Write the complete object file.  */
 482
 483 const char *
 484 simple_object_write_to_file (simple_object_write *sobj, int descriptor,
 485                              int *err)
 486 {
 487   return sobj->functions->write_to_file (sobj, descriptor, err);
 488 }
 489
 490 /* Release an simple_object_write.  */
 491
 492 void
 493 simple_object_release_write (simple_object_write *sobj)
 494 {
 495   simple_object_write_section *section;
 496
 497   free (sobj->segment_name);
 498
 499   section = sobj->sections;
 500   while (section != NULL)
 501     {
 502       struct simple_object_write_section_buffer *buffer;
 503       simple_object_write_section *next_section;
 504
 505       buffer = section->buffers;
 506       while (buffer != NULL)
 507         {
 508           struct simple_object_write_section_buffer *next_buffer;
 509
 510           if (buffer->free_buffer != NULL)
 511             XDELETEVEC (buffer->free_buffer);
 512           next_buffer = buffer->next;
 513           XDELETE (buffer);
 514           buffer = next_buffer;
 515         }
 516
 517       next_section = section->next;
 518       free (section->name);
 519       XDELETE (section);
 520       section = next_section;
 521     }
 522
 523   sobj->functions->release_write (sobj->data);
 524   XDELETE (sobj);
 525 }