libiberty/simple-object.c

   1 /* simple-object.c -- simple routines to read and write object files.
   2    Copyright (C) 2010-2021 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 #ifndef O_BINARY
  48 #define O_BINARY 0
  49 #endif
  50
  51 #include "simple-object-common.h"
  52
  53 /* The known object file formats.  */
  54
  55 static const struct simple_object_functions * const format_functions[] =
  56 {
  57   &simple_object_elf_functions,
  58   &simple_object_mach_o_functions,
  59   &simple_object_coff_functions,
  60   &simple_object_xcoff_functions
  61 };
  62
  63 /* Read data from a file using the simple_object error reporting
  64    conventions.  */
  65
  66 int
  67 simple_object_internal_read (int descriptor, off_t offset,
  68                              unsigned char *buffer, size_t size,
  69                              const char **errmsg, int *err)
  70 {
  71   if (lseek (descriptor, offset, SEEK_SET) < 0)
  72     {
  73       *errmsg = "lseek";
  74       *err = errno;
  75       return 0;
  76     }
  77
  78   do
  79     {
  80       ssize_t got = read (descriptor, buffer, size);
  81       if (got == 0)
  82         break;
  83       else if (got > 0)
  84         {
  85           buffer += got;
  86           size -= got;
  87         }
  88       else if (errno != EINTR)
  89         {
  90           *errmsg = "read";
  91           *err = errno;
  92           return 0;
  93         }
  94     }
  95   while (size > 0);
  96
  97   if (size > 0)
  98     {
  99       *errmsg = "file too short";
 100       *err = 0;
 101       return 0;
 102     }
 103
 104   return 1;
 105 }
 106
 107 /* Write data to a file using the simple_object error reporting
 108    conventions.  */
 109
 110 int
 111 simple_object_internal_write (int descriptor, off_t offset,
 112                               const unsigned char *buffer, size_t size,
 113                               const char **errmsg, int *err)
 114 {
 115   if (lseek (descriptor, offset, SEEK_SET) < 0)
 116     {
 117       *errmsg = "lseek";
 118       *err = errno;
 119       return 0;
 120     }
 121
 122   do
 123     {
 124       ssize_t wrote = write (descriptor, buffer, size);
 125       if (wrote == 0)
 126         break;
 127       else if (wrote > 0)
 128         {
 129           buffer += wrote;
 130           size -= wrote;
 131         }
 132       else if (errno != EINTR)
 133         {
 134           *errmsg = "write";
 135           *err = errno;
 136           return 0;
 137         }
 138     }
 139   while (size > 0);
 140
 141   if (size > 0)
 142     {
 143       *errmsg = "short write";
 144       *err = 0;
 145       return 0;
 146     }
 147
 148   return 1;
 149 }
 150
 151 /* Open for read.  */
 152
 153 simple_object_read *
 154 simple_object_start_read (int descriptor, off_t offset,
 155                           const char *segment_name, const char **errmsg,
 156                           int *err)
 157 {
 158   unsigned char header[SIMPLE_OBJECT_MATCH_HEADER_LEN];
 159   size_t len, i;
 160
 161   if (!simple_object_internal_read (descriptor, offset, header,
 162                                     SIMPLE_OBJECT_MATCH_HEADER_LEN,
 163                                     errmsg, err))
 164     return NULL;
 165
 166   len = sizeof (format_functions) / sizeof (format_functions[0]);
 167   for (i = 0; i < len; ++i)
 168     {
 169       void *data;
 170
 171       data = format_functions[i]->match (header, descriptor, offset,
 172                                          segment_name, errmsg, err);
 173       if (data != NULL)
 174         {
 175           simple_object_read *ret;
 176
 177           ret = XNEW (simple_object_read);
 178           ret->descriptor = descriptor;
 179           ret->offset = offset;
 180           ret->functions = format_functions[i];
 181           ret->data = data;
 182           return ret;
 183         }
 184     }
 185
 186   *errmsg = "file not recognized";
 187   *err = 0;
 188   return NULL;
 189 }
 190
 191 /* Find all sections.  */
 192
 193 const char *
 194 simple_object_find_sections (simple_object_read *sobj,
 195                              int (*pfn) (void *, const char *, off_t, off_t),
 196                              void *data,
 197                              int *err)
 198 {
 199   return sobj->functions->find_sections (sobj, pfn, data, err);
 200 }
 201
 202 /* Internal data passed to find_one_section.  */
 203
 204 struct find_one_section_data
 205 {
 206   /* The section we are looking for.  */
 207   const char *name;
 208   /* Where to store the section offset.  */
 209   off_t *offset;
 210   /* Where to store the section length.  */
 211   off_t *length;
 212   /* Set if the name is found.  */
 213   int found;
 214 };
 215
 216 /* Internal function passed to find_sections.  */
 217
 218 static int
 219 find_one_section (void *data, const char *name, off_t offset, off_t length)
 220 {
 221   struct find_one_section_data *fosd = (struct find_one_section_data *) data;
 222
 223   if (strcmp (name, fosd->name) != 0)
 224     return 1;
 225
 226   *fosd->offset = offset;
 227   *fosd->length = length;
 228   fosd->found = 1;
 229
 230   /* Stop iteration.  */
 231   return 0;
 232 }
 233
 234 /* Find a section.  */
 235
 236 int
 237 simple_object_find_section (simple_object_read *sobj, const char *name,
 238                             off_t *offset, off_t *length,
 239                             const char **errmsg, int *err)
 240 {
 241   struct find_one_section_data fosd;
 242
 243   fosd.name = name;
 244   fosd.offset = offset;
 245   fosd.length = length;
 246   fosd.found = 0;
 247
 248   *errmsg = simple_object_find_sections (sobj, find_one_section,
 249                                          (void *) &fosd, err);
 250   if (*errmsg != NULL)
 251     return 0;
 252   if (!fosd.found)
 253     return 0;
 254   return 1;
 255 }
 256
 257 /* Callback to identify and rename LTO debug sections by name.
 258    Returns non-NULL if NAME is a LTO debug section, NULL if not.
 259    If RENAME is true it will rename LTO debug sections to non-LTO
 260    ones.  */
 261
 262 static char *
 263 handle_lto_debug_sections (const char *name, int rename)
 264 {
 265   char *newname = rename ? XCNEWVEC (char, strlen (name) + 1)
 266                          : xstrdup (name);
 267
 268   /* ???  So we can't use .gnu.lto_ prefixed sections as the assembler
 269      complains about bogus section flags.  Which means we need to arrange
 270      for that to be fixed or .gnu.debuglto_ marked as SHF_EXCLUDE (to make
 271      fat lto object tooling work for the fat part).  */
 272   /* Also include corresponding reloc sections.  */
 273   if (strncmp (name, ".rela", sizeof (".rela") - 1) == 0)
 274     {
 275       if (rename)
 276         strncpy (newname, name, sizeof (".rela") - 1);
 277       name += sizeof (".rela") - 1;
 278     }
 279   else if (strncmp (name, ".rel", sizeof (".rel") - 1) == 0)
 280     {
 281       if (rename)
 282         strncpy (newname, name, sizeof (".rel") - 1);
 283       name += sizeof (".rel") - 1;
 284     }
 285   /* ???  For now this handles both .gnu.lto_ and .gnu.debuglto_ prefixed
 286      sections.  */
 287   /* Copy LTO debug sections and rename them to their non-LTO name.  */
 288   if (strncmp (name, ".gnu.debuglto_", sizeof (".gnu.debuglto_") - 1) == 0)
 289     return rename ? strcat (newname, name + sizeof (".gnu.debuglto_") - 1) : newname;
 290   else if (strncmp (name, ".gnu.lto_.debug_",
 291                     sizeof (".gnu.lto_.debug_") -1) == 0)
 292     return rename ? strcat (newname, name + sizeof (".gnu.lto_") - 1) : newname;
 293   /* Copy over .note.GNU-stack section under the same name if present.  */
 294   else if (strcmp (name, ".note.GNU-stack") == 0)
 295     return strcpy (newname, name);
 296   /* Copy over .note.gnu.property section under the same name if present.  */
 297   else if (strcmp (name, ".note.gnu.property") == 0)
 298     return strcpy (newname, name);
 299   /* Copy over .comment section under the same name if present.  Solaris
 300      ld uses them to relax its checking of ELF gABI access rules for
 301      COMDAT sections in objects produced by GCC.  */
 302   else if (strcmp (name, ".comment") == 0)
 303     return strcpy (newname, name);
 304   /* Copy over .GCC.command.line section under the same name if present.  */
 305   else if (strcmp (name, ".GCC.command.line") == 0)
 306     return strcpy (newname, name);
 307   free (newname);
 308   return NULL;
 309 }
 310
 311 /* Wrapper for handle_lto_debug_sections.  */
 312
 313 static char *
 314 handle_lto_debug_sections_rename (const char *name)
 315 {
 316   return handle_lto_debug_sections (name, 1);
 317 }
 318
 319 /* Wrapper for handle_lto_debug_sections.  */
 320
 321 static char *
 322 handle_lto_debug_sections_norename (const char *name)
 323 {
 324   return handle_lto_debug_sections (name, 0);
 325 }
 326
 327 /* Copy LTO debug sections.  */
 328
 329 const char *
 330 simple_object_copy_lto_debug_sections (simple_object_read *sobj,
 331                                        const char *dest, int *err, int rename)
 332 {
 333   const char *errmsg;
 334   simple_object_write *dest_sobj;
 335   simple_object_attributes *attrs;
 336   int outfd;
 337
 338   if (! sobj->functions->copy_lto_debug_sections)
 339     {
 340       *err = EINVAL;
 341       return "simple_object_copy_lto_debug_sections not implemented";
 342     }
 343
 344   attrs = simple_object_fetch_attributes (sobj, &errmsg, err);
 345   if (! attrs)
 346     return errmsg;
 347   dest_sobj = simple_object_start_write (attrs, NULL, &errmsg, err);
 348   simple_object_release_attributes (attrs);
 349   if (! dest_sobj)
 350     return errmsg;
 351
 352   errmsg = sobj->functions->copy_lto_debug_sections
 353                  (sobj, dest_sobj,
 354                   rename ? handle_lto_debug_sections_rename
 355                          : handle_lto_debug_sections_norename,  err);
 356   if (errmsg)
 357     {
 358       simple_object_release_write (dest_sobj);
 359       return errmsg;
 360     }
 361
 362   outfd = open (dest, O_CREAT|O_WRONLY|O_TRUNC|O_BINARY, 00777);
 363   if (outfd == -1)
 364     {
 365       *err = errno;
 366       simple_object_release_write (dest_sobj);
 367       return "open failed";
 368     }
 369
 370   errmsg = simple_object_write_to_file (dest_sobj, outfd, err);
 371   close (outfd);
 372   if (errmsg)
 373     {
 374       simple_object_release_write (dest_sobj);
 375       return errmsg;
 376     }
 377
 378   simple_object_release_write (dest_sobj);
 379   return NULL;
 380 }
 381
 382 /* Fetch attributes.  */
 383
 384 simple_object_attributes *
 385 simple_object_fetch_attributes (simple_object_read *sobj, const char **errmsg,
 386                                 int *err)
 387 {
 388   void *data;
 389   simple_object_attributes *ret;
 390
 391   data = sobj->functions->fetch_attributes (sobj, errmsg, err);
 392   if (data == NULL)
 393     return NULL;
 394   ret = XNEW (simple_object_attributes);
 395   ret->functions = sobj->functions;
 396   ret->data = data;
 397   return ret;
 398 }
 399
 400 /* Release an simple_object_read.  */
 401
 402 void
 403 simple_object_release_read (simple_object_read *sobj)
 404 {
 405   sobj->functions->release_read (sobj->data);
 406   XDELETE (sobj);
 407 }
 408
 409 /* Merge attributes.  */
 410
 411 const char *
 412 simple_object_attributes_merge (simple_object_attributes *to,
 413                                 simple_object_attributes *from,
 414                                 int *err)
 415 {
 416   if (to->functions != from->functions)
 417     {
 418       *err = 0;
 419       return "different object file format";
 420     }
 421   return to->functions->attributes_merge (to->data, from->data, err);
 422 }
 423
 424 /* Release an attributes structure.  */
 425
 426 void
 427 simple_object_release_attributes (simple_object_attributes *attrs)
 428 {
 429   attrs->functions->release_attributes (attrs->data);
 430   XDELETE (attrs);
 431 }
 432
 433 /* Start creating an object file.  */
 434
 435 simple_object_write *
 436 simple_object_start_write (simple_object_attributes *attrs,
 437                            const char *segment_name, const char **errmsg,
 438                            int *err)
 439 {
 440   void *data;
 441   simple_object_write *ret;
 442
 443   data = attrs->functions->start_write (attrs->data, errmsg, err);
 444   if (data == NULL)
 445     return NULL;
 446   ret = XNEW (simple_object_write);
 447   ret->functions = attrs->functions;
 448   ret->segment_name = segment_name ? xstrdup (segment_name) : NULL;
 449   ret->sections = NULL;
 450   ret->last_section = NULL;
 451   ret->data = data;
 452   return ret;
 453 }
 454
 455 /* Start creating a section.  */
 456
 457 simple_object_write_section *
 458 simple_object_write_create_section (simple_object_write *sobj, const char *name,
 459                                     unsigned int align,
 460                                     const char **errmsg ATTRIBUTE_UNUSED,
 461                                     int *err ATTRIBUTE_UNUSED)
 462 {
 463   simple_object_write_section *ret;
 464
 465   ret = XNEW (simple_object_write_section);
 466   ret->next = NULL;
 467   ret->name = xstrdup (name);
 468   ret->align = align;
 469   ret->buffers = NULL;
 470   ret->last_buffer = NULL;
 471
 472   if (sobj->last_section == NULL)
 473     {
 474       sobj->sections = ret;
 475       sobj->last_section = ret;
 476     }
 477   else
 478     {
 479       sobj->last_section->next = ret;
 480       sobj->last_section = ret;
 481     }
 482
 483   return ret;
 484 }
 485
 486 /* Add data to a section.  */
 487
 488 const char *
 489 simple_object_write_add_data (simple_object_write *sobj ATTRIBUTE_UNUSED,
 490                               simple_object_write_section *section,
 491                               const void *buffer,
 492                               size_t size, int copy,
 493                               int *err ATTRIBUTE_UNUSED)
 494 {
 495   struct simple_object_write_section_buffer *wsb;
 496
 497   wsb = XNEW (struct simple_object_write_section_buffer);
 498   wsb->next = NULL;
 499   wsb->size = size;
 500
 501   if (!copy)
 502     {
 503       wsb->buffer = buffer;
 504       wsb->free_buffer = NULL;
 505     }
 506   else
 507     {
 508       wsb->free_buffer = (void *) XNEWVEC (char, size);
 509       memcpy (wsb->free_buffer, buffer, size);
 510       wsb->buffer = wsb->free_buffer;
 511     }
 512
 513   if (section->last_buffer == NULL)
 514     {
 515       section->buffers = wsb;
 516       section->last_buffer = wsb;
 517     }
 518   else
 519     {
 520       section->last_buffer->next = wsb;
 521       section->last_buffer = wsb;
 522     }
 523
 524   return NULL;
 525 }
 526
 527 /* Write the complete object file.  */
 528
 529 const char *
 530 simple_object_write_to_file (simple_object_write *sobj, int descriptor,
 531                              int *err)
 532 {
 533   return sobj->functions->write_to_file (sobj, descriptor, err);
 534 }
 535
 536 /* Release an simple_object_write.  */
 537
 538 void
 539 simple_object_release_write (simple_object_write *sobj)
 540 {
 541   simple_object_write_section *section;
 542
 543   free (sobj->segment_name);
 544
 545   section = sobj->sections;
 546   while (section != NULL)
 547     {
 548       struct simple_object_write_section_buffer *buffer;
 549       simple_object_write_section *next_section;
 550
 551       buffer = section->buffers;
 552       while (buffer != NULL)
 553         {
 554           struct simple_object_write_section_buffer *next_buffer;
 555
 556           if (buffer->free_buffer != NULL)
 557             XDELETEVEC (buffer->free_buffer);
 558           next_buffer = buffer->next;
 559           XDELETE (buffer);
 560           buffer = next_buffer;
 561         }
 562
 563       next_section = section->next;
 564       free (section->name);
 565       XDELETE (section);
 566       section = next_section;
 567     }
 568
 569   sobj->functions->release_write (sobj->data);
 570   XDELETE (sobj);
 571 }