binutils/elfcomm.c

   1 /* elfcomm.c -- common code for ELF format file.
   2    Copyright (C) 2010-2022 Free Software Foundation, Inc.
   3
   4    Originally developed by Eric Youngdale <eric@andante.jic.com>
   5    Modifications by Nick Clifton <nickc@redhat.com>
   6
   7    This file is part of GNU Binutils.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
  22    02110-1301, USA.  */
  23
  24 /* Do not include bfd.h in this file.  Functions in this file are used
  25    by readelf.c and elfedit.c which define BFD64, and by objdump.c
  26    which doesn't.  */
  27
  28 #include "sysdep.h"
  29 #include "libiberty.h"
  30 #include "bfd.h"
  31 #include "filenames.h"
  32 #include "aout/ar.h"
  33 #include "elfcomm.h"
  34 #include <assert.h>
  35
  36 extern char *program_name;
  37
  38 void
  39 error (const char *message, ...)
  40 {
  41   va_list args;
  42
  43   /* Try to keep error messages in sync with the program's normal output.  */
  44   fflush (stdout);
  45
  46   va_start (args, message);
  47   fprintf (stderr, _("%s: Error: "), program_name);
  48   vfprintf (stderr, message, args);
  49   va_end (args);
  50 }
  51
  52 void
  53 warn (const char *message, ...)
  54 {
  55   va_list args;
  56
  57   /* Try to keep warning messages in sync with the program's normal output.  */
  58   fflush (stdout);
  59
  60   va_start (args, message);
  61   fprintf (stderr, _("%s: Warning: "), program_name);
  62   vfprintf (stderr, message, args);
  63   va_end (args);
  64 }
  65
  66 void (*byte_put) (unsigned char *, uint64_t, unsigned int);
  67
  68 void
  69 byte_put_little_endian (unsigned char *field, uint64_t value, unsigned int size)
  70 {
  71   if (size > sizeof (uint64_t))
  72     {
  73       error (_("Unhandled data length: %d\n"), size);
  74       abort ();
  75     }
  76   while (size--)
  77     {
  78       *field++ = value & 0xff;
  79       value >>= 8;
  80     }
  81 }
  82
  83 void
  84 byte_put_big_endian (unsigned char *field, uint64_t value, unsigned int size)
  85 {
  86   if (size > sizeof (uint64_t))
  87     {
  88       error (_("Unhandled data length: %d\n"), size);
  89       abort ();
  90     }
  91   while (size--)
  92     {
  93       field[size] = value & 0xff;
  94       value >>= 8;
  95     }
  96 }
  97
  98 uint64_t (*byte_get) (const unsigned char *, unsigned int);
  99
 100 uint64_t
 101 byte_get_little_endian (const unsigned char *field, unsigned int size)
 102 {
 103   switch (size)
 104     {
 105     case 1:
 106       return *field;
 107
 108     case 2:
 109       return ((uint64_t) field[0]
 110               | ((uint64_t) field[1] << 8));
 111
 112     case 3:
 113       return ((uint64_t) field[0]
 114               | ((uint64_t) field[1] << 8)
 115               | ((uint64_t) field[2] << 16));
 116
 117     case 4:
 118       return ((uint64_t) field[0]
 119               | ((uint64_t) field[1] << 8)
 120               | ((uint64_t) field[2] << 16)
 121               | ((uint64_t) field[3] << 24));
 122
 123     case 5:
 124       return ((uint64_t) field[0]
 125               | ((uint64_t) field[1] << 8)
 126               | ((uint64_t) field[2] << 16)
 127               | ((uint64_t) field[3] << 24)
 128               | ((uint64_t) field[4] << 32));
 129
 130     case 6:
 131       return ((uint64_t) field[0]
 132               | ((uint64_t) field[1] << 8)
 133               | ((uint64_t) field[2] << 16)
 134               | ((uint64_t) field[3] << 24)
 135               | ((uint64_t) field[4] << 32)
 136               | ((uint64_t) field[5] << 40));
 137
 138     case 7:
 139       return ((uint64_t) field[0]
 140               | ((uint64_t) field[1] << 8)
 141               | ((uint64_t) field[2] << 16)
 142               | ((uint64_t) field[3] << 24)
 143               | ((uint64_t) field[4] << 32)
 144               | ((uint64_t) field[5] << 40)
 145               | ((uint64_t) field[6] << 48));
 146
 147     case 8:
 148       return ((uint64_t) field[0]
 149               | ((uint64_t) field[1] << 8)
 150               | ((uint64_t) field[2] << 16)
 151               | ((uint64_t) field[3] << 24)
 152               | ((uint64_t) field[4] << 32)
 153               | ((uint64_t) field[5] << 40)
 154               | ((uint64_t) field[6] << 48)
 155               | ((uint64_t) field[7] << 56));
 156
 157     default:
 158       error (_("Unhandled data length: %d\n"), size);
 159       abort ();
 160     }
 161 }
 162
 163 uint64_t
 164 byte_get_big_endian (const unsigned char *field, unsigned int size)
 165 {
 166   switch (size)
 167     {
 168     case 1:
 169       return *field;
 170
 171     case 2:
 172       return ((uint64_t) field[1]
 173               | ((uint64_t) field[0] << 8));
 174
 175     case 3:
 176       return ((uint64_t) field[2]
 177               | ((uint64_t) field[1] << 8)
 178               | ((uint64_t) field[0] << 16));
 179
 180     case 4:
 181       return ((uint64_t) field[3]
 182               | ((uint64_t) field[2] << 8)
 183               | ((uint64_t) field[1] << 16)
 184               | ((uint64_t) field[0] << 24));
 185
 186     case 5:
 187       return ((uint64_t) field[4]
 188               | ((uint64_t) field[3] << 8)
 189               | ((uint64_t) field[2] << 16)
 190               | ((uint64_t) field[1] << 24)
 191               | ((uint64_t) field[0] << 32));
 192
 193     case 6:
 194       return ((uint64_t) field[5]
 195               | ((uint64_t) field[4] << 8)
 196               | ((uint64_t) field[3] << 16)
 197               | ((uint64_t) field[2] << 24)
 198               | ((uint64_t) field[1] << 32)
 199               | ((uint64_t) field[0] << 40));
 200
 201     case 7:
 202       return ((uint64_t) field[6]
 203               | ((uint64_t) field[5] << 8)
 204               | ((uint64_t) field[4] << 16)
 205               | ((uint64_t) field[3] << 24)
 206               | ((uint64_t) field[2] << 32)
 207               | ((uint64_t) field[1] << 40)
 208               | ((uint64_t) field[0] << 48));
 209
 210     case 8:
 211       return ((uint64_t) field[7]
 212               | ((uint64_t) field[6] << 8)
 213               | ((uint64_t) field[5] << 16)
 214               | ((uint64_t) field[4] << 24)
 215               | ((uint64_t) field[3] << 32)
 216               | ((uint64_t) field[2] << 40)
 217               | ((uint64_t) field[1] << 48)
 218               | ((uint64_t) field[0] << 56));
 219
 220     default:
 221       error (_("Unhandled data length: %d\n"), size);
 222       abort ();
 223     }
 224 }
 225
 226 uint64_t
 227 byte_get_signed (const unsigned char *field, unsigned int size)
 228 {
 229   uint64_t x = byte_get (field, size);
 230
 231   switch (size)
 232     {
 233     case 1:
 234       return (x ^ 0x80) - 0x80;
 235     case 2:
 236       return (x ^ 0x8000) - 0x8000;
 237     case 3:
 238       return (x ^ 0x800000) - 0x800000;
 239     case 4:
 240       return (x ^ 0x80000000) - 0x80000000;
 241     case 5:
 242     case 6:
 243     case 7:
 244     case 8:
 245       /* Reads of 5-, 6-, and 7-byte numbers are the result of
 246          trying to read past the end of a buffer, and will therefore
 247          not have meaningful values, so we don't try to deal with
 248          the sign in these cases.  */
 249       return x;
 250     default:
 251       abort ();
 252     }
 253 }
 254
 255 /* Return the path name for a proxy entry in a thin archive, adjusted
 256    relative to the path name of the thin archive itself if necessary.
 257    Always returns a pointer to malloc'ed memory.  */
 258
 259 char *
 260 adjust_relative_path (const char *file_name, const char *name,
 261                       unsigned long name_len)
 262 {
 263   char * member_file_name;
 264   const char * base_name = lbasename (file_name);
 265   size_t amt;
 266
 267   /* This is a proxy entry for a thin archive member.
 268      If the extended name table contains an absolute path
 269      name, or if the archive is in the current directory,
 270      use the path name as given.  Otherwise, we need to
 271      find the member relative to the directory where the
 272      archive is located.  */
 273   if (IS_ABSOLUTE_PATH (name) || base_name == file_name)
 274     {
 275       amt = name_len + 1;
 276       if (amt == 0)
 277         return NULL;
 278       member_file_name = (char *) malloc (amt);
 279       if (member_file_name == NULL)
 280         {
 281           error (_("Out of memory\n"));
 282           return NULL;
 283         }
 284       memcpy (member_file_name, name, name_len);
 285       member_file_name[name_len] = '\0';
 286     }
 287   else
 288     {
 289       /* Concatenate the path components of the archive file name
 290          to the relative path name from the extended name table.  */
 291       size_t prefix_len = base_name - file_name;
 292
 293       amt = prefix_len + name_len + 1;
 294       /* PR 17531: file: 2896dc8b
 295          Catch wraparound.  */
 296       if (amt < prefix_len || amt < name_len)
 297         {
 298           error (_("Abnormal length of thin archive member name: %lx\n"),
 299                  name_len);
 300           return NULL;
 301         }
 302
 303       member_file_name = (char *) malloc (amt);
 304       if (member_file_name == NULL)
 305         {
 306           error (_("Out of memory\n"));
 307           return NULL;
 308         }
 309       memcpy (member_file_name, file_name, prefix_len);
 310       memcpy (member_file_name + prefix_len, name, name_len);
 311       member_file_name[prefix_len + name_len] = '\0';
 312     }
 313   return member_file_name;
 314 }
 315
 316 /* Processes the archive index table and symbol table in ARCH.
 317    Entries in the index table are SIZEOF_AR_INDEX bytes long.
 318    Fills in ARCH->next_arhdr_offset and ARCH->arhdr.
 319    If READ_SYMBOLS is true then fills in ARCH->index_num, ARCH->index_array,
 320     ARCH->sym_size and ARCH->sym_table.
 321    It is the caller's responsibility to free ARCH->index_array and
 322     ARCH->sym_table.
 323    Returns 1 upon success, 0 otherwise.
 324    If failure occurs an error message is printed.  */
 325
 326 static int
 327 process_archive_index_and_symbols (struct archive_info *arch,
 328                                    unsigned int sizeof_ar_index,
 329                                    int read_symbols)
 330 {
 331   size_t got;
 332   unsigned long size;
 333   char fmag_save;
 334
 335   fmag_save = arch->arhdr.ar_fmag[0];
 336   arch->arhdr.ar_fmag[0] = 0;
 337   size = strtoul (arch->arhdr.ar_size, NULL, 10);
 338   arch->arhdr.ar_fmag[0] = fmag_save;
 339   /* PR 17531: file: 912bd7de.  */
 340   if ((signed long) size < 0)
 341     {
 342       error (_("%s: invalid archive header size: %ld\n"),
 343              arch->file_name, size);
 344       return 0;
 345     }
 346
 347   size = size + (size & 1);
 348
 349   arch->next_arhdr_offset += sizeof arch->arhdr + size;
 350
 351   if (! read_symbols)
 352     {
 353       if (fseek (arch->file, size, SEEK_CUR) != 0)
 354         {
 355           error (_("%s: failed to skip archive symbol table\n"),
 356                  arch->file_name);
 357           return 0;
 358         }
 359     }
 360   else
 361     {
 362       unsigned long i;
 363       /* A buffer used to hold numbers read in from an archive index.
 364          These are always SIZEOF_AR_INDEX bytes long and stored in
 365          big-endian format.  */
 366       unsigned char integer_buffer[sizeof arch->index_num];
 367       unsigned char * index_buffer;
 368
 369       assert (sizeof_ar_index <= sizeof integer_buffer);
 370
 371       /* Check the size of the archive index.  */
 372       if (size < sizeof_ar_index)
 373         {
 374           error (_("%s: the archive index is empty\n"), arch->file_name);
 375           return 0;
 376         }
 377
 378       /* Read the number of entries in the archive index.  */
 379       got = fread (integer_buffer, 1, sizeof_ar_index, arch->file);
 380       if (got != sizeof_ar_index)
 381         {
 382           error (_("%s: failed to read archive index\n"), arch->file_name);
 383           return 0;
 384         }
 385
 386       arch->index_num = byte_get_big_endian (integer_buffer, sizeof_ar_index);
 387       size -= sizeof_ar_index;
 388
 389       if (size < arch->index_num * sizeof_ar_index
 390           /* PR 17531: file: 585515d1.  */
 391           || size < arch->index_num)
 392         {
 393           error (_("%s: the archive index is supposed to have 0x%lx entries of %d bytes, but the size is only 0x%lx\n"),
 394                  arch->file_name, (long) arch->index_num, sizeof_ar_index, size);
 395           return 0;
 396         }
 397
 398       /* Read in the archive index.  */
 399       index_buffer = (unsigned char *)
 400         malloc (arch->index_num * sizeof_ar_index);
 401       if (index_buffer == NULL)
 402         {
 403           error (_("Out of memory whilst trying to read archive symbol index\n"));
 404           return 0;
 405         }
 406
 407       got = fread (index_buffer, sizeof_ar_index, arch->index_num, arch->file);
 408       if (got != arch->index_num)
 409         {
 410           free (index_buffer);
 411           error (_("%s: failed to read archive index\n"), arch->file_name);
 412           return 0;
 413         }
 414
 415       size -= arch->index_num * sizeof_ar_index;
 416
 417       /* Convert the index numbers into the host's numeric format.  */
 418       arch->index_array = (uint64_t *)
 419         malloc (arch->index_num * sizeof (*arch->index_array));
 420       if (arch->index_array == NULL)
 421         {
 422           free (index_buffer);
 423           error (_("Out of memory whilst trying to convert the archive symbol index\n"));
 424           return 0;
 425         }
 426
 427       for (i = 0; i < arch->index_num; i++)
 428         arch->index_array[i] =
 429           byte_get_big_endian ((unsigned char *) (index_buffer + (i * sizeof_ar_index)),
 430                                sizeof_ar_index);
 431       free (index_buffer);
 432
 433       /* The remaining space in the header is taken up by the symbol table.  */
 434       if (size < 1)
 435         {
 436           error (_("%s: the archive has an index but no symbols\n"),
 437                  arch->file_name);
 438           return 0;
 439         }
 440
 441       arch->sym_table = (char *) malloc (size);
 442       if (arch->sym_table == NULL)
 443         {
 444           error (_("Out of memory whilst trying to read archive index symbol table\n"));
 445           return 0;
 446         }
 447
 448       arch->sym_size = size;
 449       got = fread (arch->sym_table, 1, size, arch->file);
 450       if (got != size)
 451         {
 452           error (_("%s: failed to read archive index symbol table\n"),
 453                  arch->file_name);
 454           return 0;
 455         }
 456     }
 457
 458   /* Read the next archive header.  */
 459   got = fread (&arch->arhdr, 1, sizeof arch->arhdr, arch->file);
 460   if (got != sizeof arch->arhdr && got != 0)
 461     {
 462       error (_("%s: failed to read archive header following archive index\n"),
 463              arch->file_name);
 464       return 0;
 465     }
 466
 467   return 1;
 468 }
 469
 470 /* Read the symbol table and long-name table from an archive.  */
 471
 472 int
 473 setup_archive (struct archive_info *arch, const char *file_name,
 474                FILE *file, off_t file_size,
 475                int is_thin_archive, int read_symbols)
 476 {
 477   size_t got;
 478
 479   arch->file_name = strdup (file_name);
 480   arch->file = file;
 481   arch->index_num = 0;
 482   arch->index_array = NULL;
 483   arch->sym_table = NULL;
 484   arch->sym_size = 0;
 485   arch->longnames = NULL;
 486   arch->longnames_size = 0;
 487   arch->nested_member_origin = 0;
 488   arch->is_thin_archive = is_thin_archive;
 489   arch->uses_64bit_indices = 0;
 490   arch->next_arhdr_offset = SARMAG;
 491
 492   /* Read the first archive member header.  */
 493   if (fseek (file, SARMAG, SEEK_SET) != 0)
 494     {
 495       error (_("%s: failed to seek to first archive header\n"), file_name);
 496       return 1;
 497     }
 498   got = fread (&arch->arhdr, 1, sizeof arch->arhdr, file);
 499   if (got != sizeof arch->arhdr)
 500     {
 501       if (got == 0)
 502         return 0;
 503
 504       error (_("%s: failed to read archive header\n"), file_name);
 505       return 1;
 506     }
 507
 508   /* See if this is the archive symbol table.  */
 509   if (startswith (arch->arhdr.ar_name, "/               "))
 510     {
 511       if (! process_archive_index_and_symbols (arch, 4, read_symbols))
 512         return 1;
 513     }
 514   else if (startswith (arch->arhdr.ar_name, "/SYM64/         "))
 515     {
 516       arch->uses_64bit_indices = 1;
 517       if (! process_archive_index_and_symbols (arch, 8, read_symbols))
 518         return 1;
 519     }
 520   else if (read_symbols)
 521     printf (_("%s has no archive index\n"), file_name);
 522
 523   if (startswith (arch->arhdr.ar_name, "//              "))
 524     {
 525       /* This is the archive string table holding long member names.  */
 526       char fmag_save = arch->arhdr.ar_fmag[0];
 527       arch->arhdr.ar_fmag[0] = 0;
 528       arch->longnames_size = strtoul (arch->arhdr.ar_size, NULL, 10);
 529       arch->arhdr.ar_fmag[0] = fmag_save;
 530       /* PR 17531: file: 01068045.  */
 531       if (arch->longnames_size < 8)
 532         {
 533           error (_("%s: long name table is too small, (size = %" PRId64 ")\n"),
 534                  file_name, arch->longnames_size);
 535           return 1;
 536         }
 537       /* PR 17531: file: 639d6a26.  */
 538       if ((off_t) arch->longnames_size > file_size
 539           || (signed long) arch->longnames_size < 0)
 540         {
 541           error (_("%s: long name table is too big, (size = %#" PRIx64 ")\n"),
 542                  file_name, arch->longnames_size);
 543           return 1;
 544         }
 545
 546       arch->next_arhdr_offset += sizeof arch->arhdr + arch->longnames_size;
 547
 548       /* Plus one to allow for a string terminator.  */
 549       arch->longnames = (char *) malloc (arch->longnames_size + 1);
 550       if (arch->longnames == NULL)
 551         {
 552           error (_("Out of memory reading long symbol names in archive\n"));
 553           return 1;
 554         }
 555
 556       if (fread (arch->longnames, arch->longnames_size, 1, file) != 1)
 557         {
 558           free (arch->longnames);
 559           arch->longnames = NULL;
 560           error (_("%s: failed to read long symbol name string table\n"),
 561                  file_name);
 562           return 1;
 563         }
 564
 565       if ((arch->longnames_size & 1) != 0)
 566         getc (file);
 567
 568       arch->longnames[arch->longnames_size] = 0;
 569     }
 570
 571   return 0;
 572 }
 573
 574 /* Open and setup a nested archive, if not already open.  */
 575
 576 int
 577 setup_nested_archive (struct archive_info *nested_arch,
 578                       const char *member_file_name)
 579 {
 580   FILE * member_file;
 581   struct stat statbuf;
 582
 583   /* Have we already setup this archive?  */
 584   if (nested_arch->file_name != NULL
 585       && streq (nested_arch->file_name, member_file_name))
 586     return 0;
 587
 588   /* Close previous file and discard cached information.  */
 589   if (nested_arch->file != NULL)
 590     {
 591       fclose (nested_arch->file);
 592       nested_arch->file = NULL;
 593     }
 594   release_archive (nested_arch);
 595
 596   member_file = fopen (member_file_name, "rb");
 597   if (member_file == NULL)
 598     return 1;
 599   if (fstat (fileno (member_file), &statbuf) < 0)
 600     return 1;
 601   return setup_archive (nested_arch, member_file_name, member_file,
 602                         statbuf.st_size, 0, 0);
 603 }
 604
 605 /* Release the memory used for the archive information.  */
 606
 607 void
 608 release_archive (struct archive_info * arch)
 609 {
 610   free (arch->file_name);
 611   free (arch->index_array);
 612   free (arch->sym_table);
 613   free (arch->longnames);
 614   arch->file_name = NULL;
 615   arch->index_array = NULL;
 616   arch->sym_table = NULL;
 617   arch->longnames = NULL;
 618 }
 619
 620 /* Get the name of an archive member from the current archive header.
 621    For simple names, this will modify the ar_name field of the current
 622    archive header.  For long names, it will return a pointer to the
 623    longnames table.  For nested archives, it will open the nested archive
 624    and get the name recursively.  NESTED_ARCH is a single-entry cache so
 625    we don't keep rereading the same information from a nested archive.  */
 626
 627 char *
 628 get_archive_member_name (struct archive_info *arch,
 629                          struct archive_info *nested_arch)
 630 {
 631   unsigned long j, k;
 632
 633   if (arch->arhdr.ar_name[0] == '/')
 634     {
 635       /* We have a long name.  */
 636       char *endp;
 637       char *member_file_name;
 638       char *member_name;
 639       char fmag_save;
 640
 641       if (arch->longnames == NULL || arch->longnames_size == 0)
 642         {
 643           error (_("Archive member uses long names, but no longname table found\n"));
 644           return NULL;
 645         }
 646
 647       arch->nested_member_origin = 0;
 648       fmag_save = arch->arhdr.ar_fmag[0];
 649       arch->arhdr.ar_fmag[0] = 0;
 650       k = j = strtoul (arch->arhdr.ar_name + 1, &endp, 10);
 651       if (arch->is_thin_archive && endp != NULL && * endp == ':')
 652         arch->nested_member_origin = strtoul (endp + 1, NULL, 10);
 653       arch->arhdr.ar_fmag[0] = fmag_save;
 654
 655       if (j > arch->longnames_size)
 656         {
 657           error (_("Found long name index (%ld) beyond end of long name table\n"),j);
 658           return NULL;
 659         }
 660       while ((j < arch->longnames_size)
 661              && (arch->longnames[j] != '\n')
 662              && (arch->longnames[j] != '\0'))
 663         j++;
 664       if (j > 0 && arch->longnames[j-1] == '/')
 665         j--;
 666       if (j > arch->longnames_size)
 667         j = arch->longnames_size;
 668       arch->longnames[j] = '\0';
 669
 670       if (!arch->is_thin_archive || arch->nested_member_origin == 0)
 671         return xstrdup (arch->longnames + k);
 672
 673       /* PR 17531: file: 2896dc8b.  */
 674       if (k >= j)
 675         {
 676           error (_("Invalid Thin archive member name\n"));
 677           return NULL;
 678         }
 679
 680       /* This is a proxy for a member of a nested archive.
 681          Find the name of the member in that archive.  */
 682       member_file_name = adjust_relative_path (arch->file_name,
 683                                                arch->longnames + k, j - k);
 684       if (member_file_name != NULL
 685           && setup_nested_archive (nested_arch, member_file_name) == 0)
 686         {
 687           member_name = get_archive_member_name_at (nested_arch,
 688                                                     arch->nested_member_origin,
 689                                                     NULL);
 690           if (member_name != NULL)
 691             {
 692               free (member_file_name);
 693               return member_name;
 694             }
 695         }
 696       free (member_file_name);
 697
 698       /* Last resort: just return the name of the nested archive.  */
 699       return xstrdup (arch->longnames + k);
 700     }
 701
 702   /* We have a normal (short) name.  */
 703   for (j = 0; j < sizeof (arch->arhdr.ar_name); j++)
 704     if (arch->arhdr.ar_name[j] == '/')
 705       {
 706         arch->arhdr.ar_name[j] = '\0';
 707         return xstrdup (arch->arhdr.ar_name);
 708       }
 709
 710   /* The full ar_name field is used.  Don't rely on ar_date starting
 711      with a zero byte.  */
 712   {
 713     char *name = xmalloc (sizeof (arch->arhdr.ar_name) + 1);
 714     memcpy (name, arch->arhdr.ar_name, sizeof (arch->arhdr.ar_name));
 715     name[sizeof (arch->arhdr.ar_name)] = '\0';
 716     return name;
 717   }
 718 }
 719
 720 /* Get the name of an archive member at a given OFFSET within an archive
 721    ARCH.  */
 722
 723 char *
 724 get_archive_member_name_at (struct archive_info *arch,
 725                             unsigned long offset,
 726                             struct archive_info *nested_arch)
 727 {
 728   size_t got;
 729
 730   if (fseek (arch->file, offset, SEEK_SET) != 0)
 731     {
 732       error (_("%s: failed to seek to next file name\n"), arch->file_name);
 733       return NULL;
 734     }
 735   got = fread (&arch->arhdr, 1, sizeof arch->arhdr, arch->file);
 736   if (got != sizeof arch->arhdr)
 737     {
 738       error (_("%s: failed to read archive header\n"), arch->file_name);
 739       return NULL;
 740     }
 741   if (memcmp (arch->arhdr.ar_fmag, ARFMAG, 2) != 0)
 742     {
 743       error (_("%s: did not find a valid archive header\n"),
 744              arch->file_name);
 745       return NULL;
 746     }
 747
 748   return get_archive_member_name (arch, nested_arch);
 749 }
 750
 751 /* Construct a string showing the name of the archive member, qualified
 752    with the name of the containing archive file.  For thin archives, we
 753    use square brackets to denote the indirection.  For nested archives,
 754    we show the qualified name of the external member inside the square
 755    brackets (e.g., "thin.a[normal.a(foo.o)]").  */
 756
 757 char *
 758 make_qualified_name (struct archive_info * arch,
 759                      struct archive_info * nested_arch,
 760                      const char *member_name)
 761 {
 762   const char * error_name = _("<corrupt>");
 763   size_t len;
 764   char * name;
 765
 766   len = strlen (arch->file_name) + strlen (member_name) + 3;
 767   if (arch->is_thin_archive
 768       && arch->nested_member_origin != 0)
 769     {
 770       /* PR 15140: Allow for corrupt thin archives.  */
 771       if (nested_arch->file_name)
 772         len += strlen (nested_arch->file_name) + 2;
 773       else
 774         len += strlen (error_name) + 2;
 775     }
 776
 777   name = (char *) malloc (len);
 778   if (name == NULL)
 779     {
 780       error (_("Out of memory\n"));
 781       return NULL;
 782     }
 783
 784   if (arch->is_thin_archive
 785       && arch->nested_member_origin != 0)
 786     {
 787       if (nested_arch->file_name)
 788         snprintf (name, len, "%s[%s(%s)]", arch->file_name,
 789                   nested_arch->file_name, member_name);
 790       else
 791         snprintf (name, len, "%s[%s(%s)]", arch->file_name,
 792                   error_name, member_name);
 793     }
 794   else if (arch->is_thin_archive)
 795     snprintf (name, len, "%s[%s]", arch->file_name, member_name);
 796   else
 797     snprintf (name, len, "%s(%s)", arch->file_name, member_name);
 798
 799   return name;
 800 }