src/unexsgi.c

   1 /* Copyright (C) 1985, 1986, 1987, 1988, 1990, 1992
   2    Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   6 GNU Emacs is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Emacs is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Emacs; see the file COPYING.  If not, write to
  18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.
  20
  21 In other words, you are welcome to use, share and improve this program.
  22 You are forbidden to forbid anyone else to use, share and improve
  23 what you give them.   Help stamp out software-hoarding!  */
  24
  25
  26 /*
  27  * unexec.c - Convert a running program into an a.out file.
  28  *
  29  * Author:      Spencer W. Thomas
  30  *              Computer Science Dept.
  31  *              University of Utah
  32  * Date:        Tue Mar  2 1982
  33  * Modified heavily since then.
  34  *
  35  * Synopsis:
  36  *      unexec (new_name, a_name, data_start, bss_start, entry_address)
  37  *      char *new_name, *a_name;
  38  *      unsigned data_start, bss_start, entry_address;
  39  *
  40  * Takes a snapshot of the program and makes an a.out format file in the
  41  * file named by the string argument new_name.
  42  * If a_name is non-NULL, the symbol table will be taken from the given file.
  43  * On some machines, an existing a_name file is required.
  44  *
  45  * The boundaries within the a.out file may be adjusted with the data_start
  46  * and bss_start arguments.  Either or both may be given as 0 for defaults.
  47  *
  48  * Data_start gives the boundary between the text segment and the data
  49  * segment of the program.  The text segment can contain shared, read-only
  50  * program code and literal data, while the data segment is always unshared
  51  * and unprotected.  Data_start gives the lowest unprotected address.
  52  * The value you specify may be rounded down to a suitable boundary
  53  * as required by the machine you are using.
  54  *
  55  * Specifying zero for data_start means the boundary between text and data
  56  * should not be the same as when the program was loaded.
  57  * If NO_REMAP is defined, the argument data_start is ignored and the
  58  * segment boundaries are never changed.
  59  *
  60  * Bss_start indicates how much of the data segment is to be saved in the
  61  * a.out file and restored when the program is executed.  It gives the lowest
  62  * unsaved address, and is rounded up to a page boundary.  The default when 0
  63  * is given assumes that the entire data segment is to be stored, including
  64  * the previous data and bss as well as any additional storage allocated with
  65  * break (2).
  66  *
  67  * The new file is set up to start at entry_address.
  68  *
  69  * If you make improvements I'd like to get them too.
  70  * harpo!utah-cs!thomas, thomas@Utah-20
  71  *
  72  */
  73
  74 /* Even more heavily modified by james@bigtex.cactus.org of Dell Computer Co.
  75  * ELF support added.
  76  *
  77  * Basic theory: the data space of the running process needs to be
  78  * dumped to the output file.  Normally we would just enlarge the size
  79  * of .data, scooting everything down.  But we can't do that in ELF,
  80  * because there is often something between the .data space and the
  81  * .bss space.
  82  *
  83  * In the temacs dump below, notice that the Global Offset Table
  84  * (.got) and the Dynamic link data (.dynamic) come between .data1 and
  85  * .bss.  It does not work to overlap .data with these fields.
  86  *
  87  * The solution is to create a new .data segment.  This segment is
  88  * filled with data from the current process.  Since the contents of
  89  * various sections refer to sections by index, the new .data segment
  90  * is made the last in the table to avoid changing any existing index.
  91
  92  * This is an example of how the section headers are changed.  "Addr"
  93  * is a process virtual address.  "Offset" is a file offset.
  94
  95 raid:/nfs/raid/src/dist-18.56/src> dump -h temacs
  96
  97 temacs:
  98
  99            **** SECTION HEADER TABLE ****
 100 [No]    Type    Flags   Addr         Offset       Size          Name
 101         Link    Info    Adralgn      Entsize
 102
 103 [1]     1       2       0x80480d4    0xd4         0x13          .interp
 104         0       0       0x1          0
 105
 106 [2]     5       2       0x80480e8    0xe8         0x388         .hash
 107         3       0       0x4          0x4
 108
 109 [3]     11      2       0x8048470    0x470        0x7f0         .dynsym
 110         4       1       0x4          0x10
 111
 112 [4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
 113         0       0       0x1          0
 114
 115 [5]     9       2       0x8049010    0x1010       0x338         .rel.plt
 116         3       7       0x4          0x8
 117
 118 [6]     1       6       0x8049348    0x1348       0x3           .init
 119         0       0       0x4          0
 120
 121 [7]     1       6       0x804934c    0x134c       0x680         .plt
 122         0       0       0x4          0x4
 123
 124 [8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
 125         0       0       0x4          0
 126
 127 [9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
 128         0       0       0x4          0
 129
 130 [10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
 131         0       0       0x4          0
 132
 133 [11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
 134         0       0       0x4          0
 135
 136 [12]    1       3       0x8088330    0x3f330      0x20afc       .data
 137         0       0       0x4          0
 138
 139 [13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
 140         0       0       0x4          0
 141
 142 [14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
 143         0       0       0x4          0x4
 144
 145 [15]    6       3       0x80a9874    0x60874      0x80          .dynamic
 146         4       0       0x4          0x8
 147
 148 [16]    8       3       0x80a98f4    0x608f4      0x449c        .bss
 149         0       0       0x4          0
 150
 151 [17]    2       0       0            0x608f4      0x9b90        .symtab
 152         18      371     0x4          0x10
 153
 154 [18]    3       0       0            0x6a484      0x8526        .strtab
 155         0       0       0x1          0
 156
 157 [19]    3       0       0            0x729aa      0x93          .shstrtab
 158         0       0       0x1          0
 159
 160 [20]    1       0       0            0x72a3d      0x68b7        .comment
 161         0       0       0x1          0
 162
 163 raid:/nfs/raid/src/dist-18.56/src> dump -h xemacs
 164
 165 xemacs:
 166
 167            **** SECTION HEADER TABLE ****
 168 [No]    Type    Flags   Addr         Offset       Size          Name
 169         Link    Info    Adralgn      Entsize
 170
 171 [1]     1       2       0x80480d4    0xd4         0x13          .interp
 172         0       0       0x1          0
 173
 174 [2]     5       2       0x80480e8    0xe8         0x388         .hash
 175         3       0       0x4          0x4
 176
 177 [3]     11      2       0x8048470    0x470        0x7f0         .dynsym
 178         4       1       0x4          0x10
 179
 180 [4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
 181         0       0       0x1          0
 182
 183 [5]     9       2       0x8049010    0x1010       0x338         .rel.plt
 184         3       7       0x4          0x8
 185
 186 [6]     1       6       0x8049348    0x1348       0x3           .init
 187         0       0       0x4          0
 188
 189 [7]     1       6       0x804934c    0x134c       0x680         .plt
 190         0       0       0x4          0x4
 191
 192 [8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
 193         0       0       0x4          0
 194
 195 [9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
 196         0       0       0x4          0
 197
 198 [10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
 199         0       0       0x4          0
 200
 201 [11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
 202         0       0       0x4          0
 203
 204 [12]    1       3       0x8088330    0x3f330      0x20afc       .data
 205         0       0       0x4          0
 206
 207 [13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
 208         0       0       0x4          0
 209
 210 [14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
 211         0       0       0x4          0x4
 212
 213 [15]    6       3       0x80a9874    0x60874      0x80          .dynamic
 214         4       0       0x4          0x8
 215
 216 [16]    8       3       0x80c6800    0x7d800      0             .bss
 217         0       0       0x4          0
 218
 219 [17]    2       0       0            0x7d800      0x9b90        .symtab
 220         18      371     0x4          0x10
 221
 222 [18]    3       0       0            0x87390      0x8526        .strtab
 223         0       0       0x1          0
 224
 225 [19]    3       0       0            0x8f8b6      0x93          .shstrtab
 226         0       0       0x1          0
 227
 228 [20]    1       0       0            0x8f949      0x68b7        .comment
 229         0       0       0x1          0
 230
 231 [21]    1       3       0x80a98f4    0x608f4      0x1cf0c       .data
 232         0       0       0x4          0
 233
 234  * This is an example of how the file header is changed.  "Shoff" is
 235  * the section header offset within the file.  Since that table is
 236  * after the new .data section, it is moved.  "Shnum" is the number of
 237  * sections, which we increment.
 238  *
 239  * "Phoff" is the file offset to the program header.  "Phentsize" and
 240  * "Shentsz" are the program and section header entries sizes respectively.
 241  * These can be larger than the apparent struct sizes.
 242
 243 raid:/nfs/raid/src/dist-18.56/src> dump -f temacs
 244
 245 temacs:
 246
 247                     **** ELF HEADER ****
 248 Class        Data       Type         Machine     Version
 249 Entry        Phoff      Shoff        Flags       Ehsize
 250 Phentsize    Phnum      Shentsz      Shnum       Shstrndx
 251
 252 1            1          2            3           1
 253 0x80499cc    0x34       0x792f4      0           0x34
 254 0x20         5          0x28         21          19
 255
 256 raid:/nfs/raid/src/dist-18.56/src> dump -f xemacs
 257
 258 xemacs:
 259
 260                     **** ELF HEADER ****
 261 Class        Data       Type         Machine     Version
 262 Entry        Phoff      Shoff        Flags       Ehsize
 263 Phentsize    Phnum      Shentsz      Shnum       Shstrndx
 264
 265 1            1          2            3           1
 266 0x80499cc    0x34       0x96200      0           0x34
 267 0x20         5          0x28         22          19
 268
 269  * These are the program headers.  "Offset" is the file offset to the
 270  * segment.  "Vaddr" is the memory load address.  "Filesz" is the
 271  * segment size as it appears in the file, and "Memsz" is the size in
 272  * memory.  Below, the third segment is the code and the fourth is the
 273  * data: the difference between Filesz and Memsz is .bss
 274
 275 raid:/nfs/raid/src/dist-18.56/src> dump -o temacs
 276
 277 temacs:
 278  ***** PROGRAM EXECUTION HEADER *****
 279 Type        Offset      Vaddr       Paddr
 280 Filesz      Memsz       Flags       Align
 281
 282 6           0x34        0x8048034   0
 283 0xa0        0xa0        5           0
 284
 285 3           0xd4        0           0
 286 0x13        0           4           0
 287
 288 1           0x34        0x8048034   0
 289 0x3f2f9     0x3f2f9     5           0x1000
 290
 291 1           0x3f330     0x8088330   0
 292 0x215c4     0x25a60     7           0x1000
 293
 294 2           0x60874     0x80a9874   0
 295 0x80        0           7           0
 296
 297 raid:/nfs/raid/src/dist-18.56/src> dump -o xemacs
 298
 299 xemacs:
 300  ***** PROGRAM EXECUTION HEADER *****
 301 Type        Offset      Vaddr       Paddr
 302 Filesz      Memsz       Flags       Align
 303
 304 6           0x34        0x8048034   0
 305 0xa0        0xa0        5           0
 306
 307 3           0xd4        0           0
 308 0x13        0           4           0
 309
 310 1           0x34        0x8048034   0
 311 0x3f2f9     0x3f2f9     5           0x1000
 312
 313 1           0x3f330     0x8088330   0
 314 0x3e4d0     0x3e4d0     7           0x1000
 315
 316 2           0x60874     0x80a9874   0
 317 0x80        0           7           0
 318
 319
 320  */
 321 \f
 322 /* Modified by wtien@urbana.mcd.mot.com of Motorola Inc.
 323  *
 324  * The above mechanism does not work if the unexeced ELF file is being
 325  * re-layout by other applications (such as `strip'). All the applications
 326  * that re-layout the internal of ELF will layout all sections in ascending
 327  * order of their file offsets. After the re-layout, the data2 section will
 328  * still be the LAST section in the section header vector, but its file offset
 329  * is now being pushed far away down, and causes part of it not to be mapped
 330  * in (ie. not covered by the load segment entry in PHDR vector), therefore
 331  * causes the new binary to fail.
 332  *
 333  * The solution is to modify the unexec algorithm to insert the new data2
 334  * section header right before the new bss section header, so their file
 335  * offsets will be in the ascending order. Since some of the section's (all
 336  * sections AFTER the bss section) indexes are now changed, we also need to
 337  * modify some fields to make them point to the right sections. This is done
 338  * by macro PATCH_INDEX. All the fields that need to be patched are:
 339  *
 340  * 1. ELF header e_shstrndx field.
 341  * 2. section header sh_link and sh_info field.
 342  * 3. symbol table entry st_shndx field.
 343  *
 344  * The above example now should look like:
 345
 346            **** SECTION HEADER TABLE ****
 347 [No]    Type    Flags   Addr         Offset       Size          Name
 348         Link    Info    Adralgn      Entsize
 349
 350 [1]     1       2       0x80480d4    0xd4         0x13          .interp
 351         0       0       0x1          0
 352
 353 [2]     5       2       0x80480e8    0xe8         0x388         .hash
 354         3       0       0x4          0x4
 355
 356 [3]     11      2       0x8048470    0x470        0x7f0         .dynsym
 357         4       1       0x4          0x10
 358
 359 [4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
 360         0       0       0x1          0
 361
 362 [5]     9       2       0x8049010    0x1010       0x338         .rel.plt
 363         3       7       0x4          0x8
 364
 365 [6]     1       6       0x8049348    0x1348       0x3           .init
 366         0       0       0x4          0
 367
 368 [7]     1       6       0x804934c    0x134c       0x680         .plt
 369         0       0       0x4          0x4
 370
 371 [8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
 372         0       0       0x4          0
 373
 374 [9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
 375         0       0       0x4          0
 376
 377 [10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
 378         0       0       0x4          0
 379
 380 [11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
 381         0       0       0x4          0
 382
 383 [12]    1       3       0x8088330    0x3f330      0x20afc       .data
 384         0       0       0x4          0
 385
 386 [13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
 387         0       0       0x4          0
 388
 389 [14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
 390         0       0       0x4          0x4
 391
 392 [15]    6       3       0x80a9874    0x60874      0x80          .dynamic
 393         4       0       0x4          0x8
 394
 395 [16]    1       3       0x80a98f4    0x608f4      0x1cf0c       .data
 396         0       0       0x4          0
 397
 398 [17]    8       3       0x80c6800    0x7d800      0             .bss
 399         0       0       0x4          0
 400
 401 [18]    2       0       0            0x7d800      0x9b90        .symtab
 402         19      371     0x4          0x10
 403
 404 [19]    3       0       0            0x87390      0x8526        .strtab
 405         0       0       0x1          0
 406
 407 [20]    3       0       0            0x8f8b6      0x93          .shstrtab
 408         0       0       0x1          0
 409
 410 [21]    1       0       0            0x8f949      0x68b7        .comment
 411         0       0       0x1          0
 412
 413  */
 414 \f
 415 #include <config.h>
 416 #include <sys/types.h>
 417 #include <stdio.h>
 418 #include <sys/stat.h>
 419 #include <memory.h>
 420 #include <string.h>
 421 #include <errno.h>
 422 #include <unistd.h>
 423 #include <fcntl.h>
 424 #include <elf.h>
 425 #include <syms.h> /* for HDRR declaration */
 426 #include <sys/mman.h>
 427
 428 #ifndef emacs
 429 #define fatal(a, b, c) fprintf(stderr, a, b, c), exit(1)
 430 #else
 431 extern void fatal(char *, ...);
 432 #endif
 433
 434 /* Get the address of a particular section or program header entry,
 435  * accounting for the size of the entries.
 436  */
 437
 438 #define OLD_SECTION_H(n) \
 439      (*(Elf32_Shdr *) ((byte *) old_section_h + old_file_h->e_shentsize * (n)))
 440 #define NEW_SECTION_H(n) \
 441      (*(Elf32_Shdr *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
 442 #define OLD_PROGRAM_H(n) \
 443      (*(Elf32_Phdr *) ((byte *) old_program_h + old_file_h->e_phentsize * (n)))
 444 #define NEW_PROGRAM_H(n) \
 445      (*(Elf32_Phdr *) ((byte *) new_program_h + new_file_h->e_phentsize * (n)))
 446
 447 #define PATCH_INDEX(n) \
 448   do { \
 449          if ((n) >= old_bss_index) \
 450            (n)++; } while (0)
 451 typedef unsigned char byte;
 452
 453 /* Round X up to a multiple of Y.  */
 454
 455 int
 456 round_up (x, y)
 457      int x, y;
 458 {
 459   int rem = x % y;
 460   if (rem == 0)
 461     return x;
 462   return x - rem + y;
 463 }
 464
 465 /* Return the index of the section named NAME.
 466    SECTION_NAMES, FILE_NAME and FILE_H give information
 467    about the file we are looking in.
 468
 469    If we don't find the section NAME, that is a fatal error
 470    if NOERROR is 0; we return -1 if NOERROR is nonzero.  */
 471
 472 static int
 473 find_section (name, section_names, file_name, old_file_h, old_section_h, noerror)
 474      char *name;
 475      char *section_names;
 476      char *file_name;
 477      Elf32_Ehdr *old_file_h;
 478      Elf32_Shdr *old_section_h;
 479      int noerror;
 480 {
 481   int idx;
 482
 483   for (idx = 1; idx < old_file_h->e_shnum; idx++)
 484     {
 485 #ifdef DEBUG
 486       fprintf (stderr, "Looking for %s - found %s\n", name,
 487                section_names + OLD_SECTION_H (idx).sh_name);
 488 #endif
 489       if (!strcmp (section_names + OLD_SECTION_H (idx).sh_name,
 490                    name))
 491         break;
 492     }
 493   if (idx == old_file_h->e_shnum)
 494     {
 495       if (noerror)
 496         return -1;
 497       else
 498         fatal ("Can't find .bss in %s.\n", file_name, 0);
 499     }
 500
 501   return idx;
 502 }
 503
 504 /* ****************************************************************
 505  * unexec
 506  *
 507  * driving logic.
 508  *
 509  * In ELF, this works by replacing the old .bss section with a new
 510  * .data section, and inserting an empty .bss immediately afterwards.
 511  *
 512  */
 513 void
 514 unexec (new_name, old_name, data_start, bss_start, entry_address)
 515      char *new_name, *old_name;
 516      unsigned data_start, bss_start, entry_address;
 517 {
 518   extern unsigned int bss_end;
 519   int new_file, old_file, new_file_size;
 520
 521   /* Pointers to the base of the image of the two files.  */
 522   caddr_t old_base, new_base;
 523
 524   /* Pointers to the file, program and section headers for the old and new
 525      files.  */
 526   Elf32_Ehdr *old_file_h, *new_file_h;
 527   Elf32_Phdr *old_program_h, *new_program_h;
 528   Elf32_Shdr *old_section_h, *new_section_h;
 529
 530   /* Point to the section name table in the old file.  */
 531   char *old_section_names;
 532
 533   Elf32_Addr old_bss_addr, new_bss_addr;
 534   Elf32_Word old_bss_size, new_data2_size;
 535   Elf32_Off  new_data2_offset;
 536   Elf32_Addr new_data2_addr;
 537   Elf32_Addr new_offsets_shift;
 538
 539   int n, nn, old_bss_index, old_data_index, new_data2_index;
 540   int old_mdebug_index;
 541   struct stat stat_buf;
 542
 543   /* Open the old file & map it into the address space.  */
 544
 545   old_file = open (old_name, O_RDONLY);
 546
 547   if (old_file < 0)
 548     fatal ("Can't open %s for reading: errno %d\n", old_name, errno);
 549
 550   if (fstat (old_file, &stat_buf) == -1)
 551     fatal ("Can't fstat(%s): errno %d\n", old_name, errno);
 552
 553   old_base = mmap (0, stat_buf.st_size, PROT_READ, MAP_SHARED, old_file, 0);
 554
 555   if (old_base == (caddr_t) -1)
 556     fatal ("Can't mmap(%s): errno %d\n", old_name, errno);
 557
 558 #ifdef DEBUG
 559   fprintf (stderr, "mmap(%s, %x) -> %x\n", old_name, stat_buf.st_size,
 560            old_base);
 561 #endif
 562
 563   /* Get pointers to headers & section names.  */
 564
 565   old_file_h = (Elf32_Ehdr *) old_base;
 566   old_program_h = (Elf32_Phdr *) ((byte *) old_base + old_file_h->e_phoff);
 567   old_section_h = (Elf32_Shdr *) ((byte *) old_base + old_file_h->e_shoff);
 568   old_section_names
 569     = (char *) old_base + OLD_SECTION_H (old_file_h->e_shstrndx).sh_offset;
 570
 571   /* Find the mdebug section, if any.  */
 572
 573   old_mdebug_index = find_section (".mdebug", old_section_names,
 574                                    old_name, old_file_h, old_section_h, 1);
 575
 576   /* Find the old .bss section. */
 577
 578   old_bss_index = find_section (".bss", old_section_names,
 579                                 old_name, old_file_h, old_section_h, 0);
 580
 581   /* Find the old .data section.  Figure out parameters of
 582      the new data2 and bss sections.  */
 583
 584   old_data_index = find_section (".data", old_section_names,
 585                                  old_name, old_file_h, old_section_h, 0);
 586
 587   old_bss_addr = OLD_SECTION_H (old_bss_index).sh_addr;
 588   old_bss_size = OLD_SECTION_H (old_bss_index).sh_size;
 589 #if defined(emacs) || !defined(DEBUG)
 590   bss_end = (unsigned int) sbrk (0);
 591   new_bss_addr = (Elf32_Addr) bss_end;
 592 #else
 593   new_bss_addr = old_bss_addr + old_bss_size + 0x1234;
 594 #endif
 595   new_data2_addr = old_bss_addr;
 596   new_data2_size = new_bss_addr - old_bss_addr;
 597   new_data2_offset  = OLD_SECTION_H (old_data_index).sh_offset +
 598     (new_data2_addr - OLD_SECTION_H (old_data_index).sh_addr);
 599   new_offsets_shift = new_bss_addr -
 600     ((old_bss_addr & ~0xfff) + ((old_bss_addr & 0xfff) ? 0x1000 : 0));
 601
 602 #ifdef DEBUG
 603   fprintf (stderr, "old_bss_index %d\n", old_bss_index);
 604   fprintf (stderr, "old_bss_addr %x\n", old_bss_addr);
 605   fprintf (stderr, "old_bss_size %x\n", old_bss_size);
 606   fprintf (stderr, "new_bss_addr %x\n", new_bss_addr);
 607   fprintf (stderr, "new_data2_addr %x\n", new_data2_addr);
 608   fprintf (stderr, "new_data2_size %x\n", new_data2_size);
 609   fprintf (stderr, "new_data2_offset %x\n", new_data2_offset);
 610   fprintf (stderr, "new_offsets_shift %x\n", new_offsets_shift);
 611 #endif
 612
 613   if ((unsigned) new_bss_addr < (unsigned) old_bss_addr + old_bss_size)
 614     fatal (".bss shrank when undumping???\n", 0, 0);
 615
 616   /* Set the output file to the right size and mmap it.  Set
 617      pointers to various interesting objects.  stat_buf still has
 618      old_file data.  */
 619
 620   new_file = open (new_name, O_RDWR | O_CREAT, 0666);
 621   if (new_file < 0)
 622     fatal ("Can't creat (%s): errno %d\n", new_name, errno);
 623
 624   new_file_size = stat_buf.st_size + old_file_h->e_shentsize + new_offsets_shift;
 625
 626   if (ftruncate (new_file, new_file_size))
 627     fatal ("Can't ftruncate (%s): errno %d\n", new_name, errno);
 628
 629   new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_SHARED,
 630                    new_file, 0);
 631
 632   if (new_base == (caddr_t) -1)
 633     fatal ("Can't mmap (%s): errno %d\n", new_name, errno);
 634
 635   new_file_h = (Elf32_Ehdr *) new_base;
 636   new_program_h = (Elf32_Phdr *) ((byte *) new_base + old_file_h->e_phoff);
 637   new_section_h
 638     = (Elf32_Shdr *) ((byte *) new_base + old_file_h->e_shoff
 639                       + new_offsets_shift);
 640
 641   /* Make our new file, program and section headers as copies of the
 642      originals.  */
 643
 644   memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
 645   memcpy (new_program_h, old_program_h,
 646           old_file_h->e_phnum * old_file_h->e_phentsize);
 647
 648   /* Modify the e_shstrndx if necessary. */
 649   PATCH_INDEX (new_file_h->e_shstrndx);
 650
 651   /* Fix up file header.  We'll add one section.  Section header is
 652      further away now.  */
 653
 654   new_file_h->e_shoff += new_offsets_shift;
 655   new_file_h->e_shnum += 1;
 656
 657 #ifdef DEBUG
 658   fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff);
 659   fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum);
 660   fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff);
 661   fprintf (stderr, "New section count %d\n", new_file_h->e_shnum);
 662 #endif
 663
 664   /* Fix up a new program header.  Extend the writable data segment so
 665      that the bss area is covered too. Find that segment by looking
 666      for a segment that ends just before the .bss area.  Make sure
 667      that no segments are above the new .data2.  Put a loop at the end
 668      to adjust the offset and address of any segment that is above
 669      data2, just in case we decide to allow this later.  */
 670
 671   for (n = new_file_h->e_phnum - 1; n >= 0; n--)
 672     {
 673       /* Compute maximum of all requirements for alignment of section.  */
 674       int alignment = (NEW_PROGRAM_H (n)).p_align;
 675       if ((OLD_SECTION_H (old_bss_index)).sh_addralign > alignment)
 676         alignment = OLD_SECTION_H (old_bss_index).sh_addralign;
 677
 678       /* Supposedly this condition is okay for the SGI.  */
 679 #if 0
 680       if (NEW_PROGRAM_H (n).p_vaddr + NEW_PROGRAM_H (n).p_filesz > old_bss_addr)
 681         fatal ("Program segment above .bss in %s\n", old_name, 0);
 682 #endif
 683
 684       if (NEW_PROGRAM_H (n).p_type == PT_LOAD
 685           && (round_up ((NEW_PROGRAM_H (n)).p_vaddr
 686                         + (NEW_PROGRAM_H (n)).p_filesz,
 687                         alignment)
 688               == round_up (old_bss_addr, alignment)))
 689         break;
 690     }
 691   if (n < 0)
 692     fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0);
 693
 694   NEW_PROGRAM_H (n).p_filesz += new_offsets_shift;
 695   NEW_PROGRAM_H (n).p_memsz = NEW_PROGRAM_H (n).p_filesz;
 696
 697 #if 1                           /* Maybe allow section after data2 - does this ever happen?  */
 698   for (n = new_file_h->e_phnum - 1; n >= 0; n--)
 699     {
 700       if (NEW_PROGRAM_H (n).p_vaddr
 701           && NEW_PROGRAM_H (n).p_vaddr >= new_data2_addr)
 702         NEW_PROGRAM_H (n).p_vaddr += new_offsets_shift - old_bss_size;
 703
 704       if (NEW_PROGRAM_H (n).p_offset >= new_data2_offset)
 705         NEW_PROGRAM_H (n).p_offset += new_offsets_shift;
 706     }
 707 #endif
 708
 709   /* Fix up section headers based on new .data2 section.  Any section
 710      whose offset or virtual address is after the new .data2 section
 711      gets its value adjusted.  .bss size becomes zero and new address
 712      is set.  data2 section header gets added by copying the existing
 713      .data header and modifying the offset, address and size.  */
 714   for (old_data_index = 1; old_data_index < old_file_h->e_shnum;
 715        old_data_index++)
 716     if (!strcmp (old_section_names + OLD_SECTION_H (old_data_index).sh_name,
 717                  ".data"))
 718       break;
 719   if (old_data_index == old_file_h->e_shnum)
 720     fatal ("Can't find .data in %s.\n", old_name, 0);
 721
 722   /* Walk through all section headers, insert the new data2 section right
 723      before the new bss section.  */
 724   for (n = 1, nn = 1; n < old_file_h->e_shnum; n++, nn++)
 725     {
 726       caddr_t src;
 727
 728       /* If it is bss section, insert the new data2 section before it.  */
 729       if (n == old_bss_index)
 730         {
 731           /* Steal the data section header for this data2 section.  */
 732           memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (old_data_index),
 733                   new_file_h->e_shentsize);
 734
 735           NEW_SECTION_H (nn).sh_addr = new_data2_addr;
 736           NEW_SECTION_H (nn).sh_offset = new_data2_offset;
 737           NEW_SECTION_H (nn).sh_size = new_data2_size;
 738           /* Use the bss section's alignment. This will assure that the
 739              new data2 section always be placed in the same spot as the old
 740              bss section by any other application.  */
 741           NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (n).sh_addralign;
 742
 743           /* Now copy over what we have in the memory now.  */
 744           memcpy (NEW_SECTION_H (nn).sh_offset + new_base,
 745                   (caddr_t) OLD_SECTION_H (n).sh_addr,
 746                   new_data2_size);
 747           nn++;
 748           memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n),
 749                   old_file_h->e_shentsize);
 750
 751           /* The new bss section's size is zero, and its file offset and virtual
 752              address should be off by NEW_OFFSETS_SHIFT.  */
 753           NEW_SECTION_H (nn).sh_offset += new_offsets_shift;
 754           NEW_SECTION_H (nn).sh_addr    = new_bss_addr;
 755           /* Let the new bss section address alignment be the same as the
 756              section address alignment followed the old bss section, so
 757              this section will be placed in exactly the same place.  */
 758           NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (nn).sh_addralign;
 759           NEW_SECTION_H (nn).sh_size = 0;
 760         }
 761       else
 762         {
 763           memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n),
 764                   old_file_h->e_shentsize);
 765
 766           /* Any section that was original placed AFTER the bss
 767              section must now be adjusted by NEW_OFFSETS_SHIFT.  */
 768
 769           if (NEW_SECTION_H (nn).sh_offset >= new_data2_offset)
 770             NEW_SECTION_H (nn).sh_offset += new_offsets_shift;
 771         }
 772
 773       /* If any section hdr refers to the section after the new .data
 774          section, make it refer to next one because we have inserted
 775          a new section in between.  */
 776
 777       PATCH_INDEX (NEW_SECTION_H (nn).sh_link);
 778       /* For symbol tables, info is a symbol table index,
 779          so don't change it.  */
 780       if (NEW_SECTION_H (nn).sh_type != SHT_SYMTAB
 781           && NEW_SECTION_H (nn).sh_type != SHT_DYNSYM)
 782         PATCH_INDEX (NEW_SECTION_H (nn).sh_info);
 783
 784       /* Now, start to copy the content of sections. */
 785       if (NEW_SECTION_H (nn).sh_type == SHT_NULL
 786           || NEW_SECTION_H (nn).sh_type == SHT_NOBITS)
 787         continue;
 788
 789       /* Write out the sections. .data and .data1 (and data2, called
 790          ".data" in the strings table) get copied from the current process
 791          instead of the old file.  */
 792       if (!strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data")
 793           || !strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data1")
 794 #ifdef IRIX6_5
 795           /* Under IRIX 6.5 gcc places objects with adresses relative to
 796              shared symbols in the section .rodata, which are adjusted at
 797              startup time. Unfortunately they aren't adjusted after unexec,
 798              so with this configuration we must get .rodata also from memory.
 799              Do any other configurations need this, too?
 800              <Wolfgang.Glas@hfm.tu-graz.ac.at> 1999-06-08.  */
 801           || !strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".rodata")
 802 #endif
 803           || !strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".got"))
 804         src = (caddr_t) OLD_SECTION_H (n).sh_addr;
 805       else
 806         src = old_base + OLD_SECTION_H (n).sh_offset;
 807
 808       memcpy (NEW_SECTION_H (nn).sh_offset + new_base, src,
 809               NEW_SECTION_H (nn).sh_size);
 810
 811       /* Adjust  the HDRR offsets in .mdebug and copy the
 812          line data if it's in its usual 'hole' in the object.
 813          Makes the new file debuggable with dbx.
 814          patches up two problems: the absolute file offsets
 815          in the HDRR record of .mdebug (see /usr/include/syms.h), and
 816          the ld bug that gets the line table in a hole in the
 817          elf file rather than in the .mdebug section proper.
 818          David Anderson. davea@sgi.com  Jan 16,1994.  */
 819       if (n == old_mdebug_index)
 820         {
 821 #define MDEBUGADJUST(__ct,__fileaddr)           \
 822   if (n_phdrr->__ct > 0)                        \
 823     {                                           \
 824       n_phdrr->__fileaddr += movement;          \
 825     }
 826
 827           HDRR * o_phdrr = (HDRR *)((byte *)old_base + OLD_SECTION_H (n).sh_offset);
 828           HDRR * n_phdrr = (HDRR *)((byte *)new_base + NEW_SECTION_H (nn).sh_offset);
 829           unsigned movement = new_offsets_shift;
 830
 831           MDEBUGADJUST (idnMax, cbDnOffset);
 832           MDEBUGADJUST (ipdMax, cbPdOffset);
 833           MDEBUGADJUST (isymMax, cbSymOffset);
 834           MDEBUGADJUST (ioptMax, cbOptOffset);
 835           MDEBUGADJUST (iauxMax, cbAuxOffset);
 836           MDEBUGADJUST (issMax, cbSsOffset);
 837           MDEBUGADJUST (issExtMax, cbSsExtOffset);
 838           MDEBUGADJUST (ifdMax, cbFdOffset);
 839           MDEBUGADJUST (crfd, cbRfdOffset);
 840           MDEBUGADJUST (iextMax, cbExtOffset);
 841           /* The Line Section, being possible off in a hole of the object,
 842              requires special handling.  */
 843           if (n_phdrr->cbLine > 0)
 844             {
 845               if (o_phdrr->cbLineOffset > (OLD_SECTION_H (n).sh_offset
 846                                            + OLD_SECTION_H (n).sh_size))
 847                 {
 848                   /* line data is in a hole in elf. do special copy and adjust
 849                      for this ld mistake.
 850                      */
 851                   n_phdrr->cbLineOffset += movement;
 852
 853                   memcpy (n_phdrr->cbLineOffset + new_base,
 854                           o_phdrr->cbLineOffset + old_base, n_phdrr->cbLine);
 855                 }
 856               else
 857                 {
 858                   /* somehow line data is in .mdebug as it is supposed to be.  */
 859                   MDEBUGADJUST (cbLine, cbLineOffset);
 860                 }
 861             }
 862         }
 863
 864       /* If it is the symbol table, its st_shndx field needs to be patched. */
 865       if (NEW_SECTION_H (nn).sh_type == SHT_SYMTAB
 866           || NEW_SECTION_H (nn).sh_type == SHT_DYNSYM)
 867         {
 868           Elf32_Shdr *spt = &NEW_SECTION_H (nn);
 869           unsigned int num = spt->sh_size / spt->sh_entsize;
 870           Elf32_Sym * sym = (Elf32_Sym *) (NEW_SECTION_H (nn).sh_offset
 871                                            + new_base);
 872           for (; num--; sym++)
 873             {
 874               /* don't patch special section indices. */
 875               if (sym->st_shndx == SHN_UNDEF
 876                   || sym->st_shndx >= SHN_LORESERVE)
 877                 continue;
 878
 879               PATCH_INDEX (sym->st_shndx);
 880             }
 881         }
 882     }
 883
 884   /* Close the files and make the new file executable.  */
 885
 886   if (close (old_file))
 887     fatal ("Can't close (%s): errno %d\n", old_name, errno);
 888
 889   if (close (new_file))
 890     fatal ("Can't close (%s): errno %d\n", new_name, errno);
 891
 892   if (stat (new_name, &stat_buf) == -1)
 893     fatal ("Can't stat (%s): errno %d\n", new_name, errno);
 894
 895   n = umask (777);
 896   umask (n);
 897   stat_buf.st_mode |= 0111 & ~n;
 898   if (chmod (new_name, stat_buf.st_mode) == -1)
 899     fatal ("Can't chmod (%s): errno %d\n", new_name, errno);
 900 }