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   return 0;
 277 }
 278
 279 /* Copy LTO debug sections.  */
 280
 281 const char *
 282 simple_object_copy_lto_debug_sections (simple_object_read *sobj,
 283                                        const char *dest, int *err)
 284 {
 285   const char *errmsg;
 286   simple_object_write *dest_sobj;
 287   simple_object_attributes *attrs;
 288   int outfd;
 289
 290   if (! sobj->functions->copy_lto_debug_sections)
 291     {
 292       *err = EINVAL;
 293       return "simple_object_copy_lto_debug_sections not implemented";
 294     }
 295
 296   attrs = simple_object_fetch_attributes (sobj, &errmsg, err);
 297   if (! attrs)
 298     return errmsg;
 299   dest_sobj = simple_object_start_write (attrs, NULL, &errmsg, err);
 300   simple_object_release_attributes (attrs);
 301   if (! dest_sobj)
 302     return errmsg;
 303
 304   errmsg = sobj->functions->copy_lto_debug_sections (sobj, dest_sobj,
 305                                                      handle_lto_debug_sections,
 306                                                      err);
 307   if (errmsg)
 308     {
 309       simple_object_release_write (dest_sobj);
 310       return errmsg;
 311     }
 312
 313   outfd = creat (dest, 00777);
 314   if (outfd == -1)
 315     {
 316       *err = errno;
 317       simple_object_release_write (dest_sobj);
 318       return "open failed";
 319     }
 320
 321   errmsg = simple_object_write_to_file (dest_sobj, outfd, err);
 322   close (outfd);
 323   if (errmsg)
 324     {
 325       simple_object_release_write (dest_sobj);
 326       return errmsg;
 327     }
 328
 329   simple_object_release_write (dest_sobj);
 330   return NULL;
 331 }
 332
 333 /* Fetch attributes.  */
 334
 335 simple_object_attributes *
 336 simple_object_fetch_attributes (simple_object_read *sobj, const char **errmsg,
 337                                 int *err)
 338 {
 339   void *data;
 340   simple_object_attributes *ret;
 341
 342   data = sobj->functions->fetch_attributes (sobj, errmsg, err);
 343   if (data == NULL)
 344     return NULL;
 345   ret = XNEW (simple_object_attributes);
 346   ret->functions = sobj->functions;
 347   ret->data = data;
 348   return ret;
 349 }
 350
 351 /* Release an simple_object_read.  */
 352
 353 void
 354 simple_object_release_read (simple_object_read *sobj)
 355 {
 356   sobj->functions->release_read (sobj->data);
 357   XDELETE (sobj);
 358 }
 359
 360 /* Merge attributes.  */
 361
 362 const char *
 363 simple_object_attributes_merge (simple_object_attributes *to,
 364                                 simple_object_attributes *from,
 365                                 int *err)
 366 {
 367   if (to->functions != from->functions)
 368     {
 369       *err = 0;
 370       return "different object file format";
 371     }
 372   return to->functions->attributes_merge (to->data, from->data, err);
 373 }
 374
 375 /* Release an attributes structure.  */
 376
 377 void
 378 simple_object_release_attributes (simple_object_attributes *attrs)
 379 {
 380   attrs->functions->release_attributes (attrs->data);
 381   XDELETE (attrs);
 382 }
 383
 384 /* Start creating an object file.  */
 385
 386 simple_object_write *
 387 simple_object_start_write (simple_object_attributes *attrs,
 388                            const char *segment_name, const char **errmsg,
 389                            int *err)
 390 {
 391   void *data;
 392   simple_object_write *ret;
 393
 394   data = attrs->functions->start_write (attrs->data, errmsg, err);
 395   if (data == NULL)
 396     return NULL;
 397   ret = XNEW (simple_object_write);
 398   ret->functions = attrs->functions;
 399   ret->segment_name = segment_name ? xstrdup (segment_name) : NULL;
 400   ret->sections = NULL;
 401   ret->last_section = NULL;
 402   ret->data = data;
 403   return ret;
 404 }
 405
 406 /* Start creating a section.  */
 407
 408 simple_object_write_section *
 409 simple_object_write_create_section (simple_object_write *sobj, const char *name,
 410                                     unsigned int align,
 411                                     const char **errmsg ATTRIBUTE_UNUSED,
 412                                     int *err ATTRIBUTE_UNUSED)
 413 {
 414   simple_object_write_section *ret;
 415
 416   ret = XNEW (simple_object_write_section);
 417   ret->next = NULL;
 418   ret->name = xstrdup (name);
 419   ret->align = align;
 420   ret->buffers = NULL;
 421   ret->last_buffer = NULL;
 422
 423   if (sobj->last_section == NULL)
 424     {
 425       sobj->sections = ret;
 426       sobj->last_section = ret;
 427     }
 428   else
 429     {
 430       sobj->last_section->next = ret;
 431       sobj->last_section = ret;
 432     }
 433
 434   return ret;
 435 }
 436
 437 /* Add data to a section.  */
 438
 439 const char *
 440 simple_object_write_add_data (simple_object_write *sobj ATTRIBUTE_UNUSED,
 441                               simple_object_write_section *section,
 442                               const void *buffer,
 443                               size_t size, int copy,
 444                               int *err ATTRIBUTE_UNUSED)
 445 {
 446   struct simple_object_write_section_buffer *wsb;
 447
 448   wsb = XNEW (struct simple_object_write_section_buffer);
 449   wsb->next = NULL;
 450   wsb->size = size;
 451
 452   if (!copy)
 453     {
 454       wsb->buffer = buffer;
 455       wsb->free_buffer = NULL;
 456     }
 457   else
 458     {
 459       wsb->free_buffer = (void *) XNEWVEC (char, size);
 460       memcpy (wsb->free_buffer, buffer, size);
 461       wsb->buffer = wsb->free_buffer;
 462     }
 463
 464   if (section->last_buffer == NULL)
 465     {
 466       section->buffers = wsb;
 467       section->last_buffer = wsb;
 468     }
 469   else
 470     {
 471       section->last_buffer->next = wsb;
 472       section->last_buffer = wsb;
 473     }
 474
 475   return NULL;
 476 }
 477
 478 /* Write the complete object file.  */
 479
 480 const char *
 481 simple_object_write_to_file (simple_object_write *sobj, int descriptor,
 482                              int *err)
 483 {
 484   return sobj->functions->write_to_file (sobj, descriptor, err);
 485 }
 486
 487 /* Release an simple_object_write.  */
 488
 489 void
 490 simple_object_release_write (simple_object_write *sobj)
 491 {
 492   simple_object_write_section *section;
 493
 494   free (sobj->segment_name);
 495
 496   section = sobj->sections;
 497   while (section != NULL)
 498     {
 499       struct simple_object_write_section_buffer *buffer;
 500       simple_object_write_section *next_section;
 501
 502       buffer = section->buffers;
 503       while (buffer != NULL)
 504         {
 505           struct simple_object_write_section_buffer *next_buffer;
 506
 507           if (buffer->free_buffer != NULL)
 508             XDELETEVEC (buffer->free_buffer);
 509           next_buffer = buffer->next;
 510           XDELETE (buffer);
 511           buffer = next_buffer;
 512         }
 513
 514       next_section = section->next;
 515       free (section->name);
 516       XDELETE (section);
 517       section = next_section;
 518     }
 519
 520   sobj->functions->release_write (sobj->data);
 521   XDELETE (sobj);
 522 }