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 <sys/types.h>
 416 #include <stdio.h>
 417 #include <sys/stat.h>
 418 #include <memory.h>
 419 #include <string.h>
 420 #include <errno.h>
 421 #include <unistd.h>
 422 #include <fcntl.h>
 423 #include <elf.h>
 424 #include <syms.h> /* for HDRR declaration */
 425 #include <sys/mman.h>
 426
 427 #ifndef emacs
 428 #define fatal(a, b, c) fprintf(stderr, a, b, c), exit(1)
 429 #else
 430 extern void fatal(char *, ...);
 431 #endif
 432
 433 /* Get the address of a particular section or program header entry,
 434  * accounting for the size of the entries.
 435  */
 436
 437 #define OLD_SECTION_H(n) \
 438      (*(Elf32_Shdr *) ((byte *) old_section_h + old_file_h->e_shentsize * (n)))
 439 #define NEW_SECTION_H(n) \
 440      (*(Elf32_Shdr *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
 441 #define OLD_PROGRAM_H(n) \
 442      (*(Elf32_Phdr *) ((byte *) old_program_h + old_file_h->e_phentsize * (n)))
 443 #define NEW_PROGRAM_H(n) \
 444      (*(Elf32_Phdr *) ((byte *) new_program_h + new_file_h->e_phentsize * (n)))
 445
 446 #define PATCH_INDEX(n) \
 447   do { \
 448          if ((n) >= old_bss_index) \
 449            (n)++; } while (0)
 450 typedef unsigned char byte;
 451
 452 /* Round X up to a multiple of Y.  */
 453
 454 int
 455 round_up (x, y)
 456      int x, y;
 457 {
 458   int rem = x % y;
 459   if (rem == 0)
 460     return x;
 461   return x - rem + y;
 462 }
 463
 464 /* Return the index of the section named NAME.
 465    SECTION_NAMES, FILE_NAME and FILE_H give information
 466    about the file we are looking in.
 467
 468    If we don't find the section NAME, that is a fatal error
 469    if NOERROR is 0; we return -1 if NOERROR is nonzero.  */
 470
 471 static int
 472 find_section (name, section_names, file_name, old_file_h, old_section_h, noerror)
 473      char *name;
 474      char *section_names;
 475      char *file_name;
 476      Elf32_Ehdr *old_file_h;
 477      Elf32_Shdr *old_section_h;
 478      int noerror;
 479 {
 480   int idx;
 481
 482   for (idx = 1; idx < old_file_h->e_shnum; idx++)
 483     {
 484 #ifdef DEBUG
 485       fprintf (stderr, "Looking for %s - found %s\n", name,
 486                section_names + OLD_SECTION_H (idx).sh_name);
 487 #endif
 488       if (!strcmp (section_names + OLD_SECTION_H (idx).sh_name,
 489                    name))
 490         break;
 491     }
 492   if (idx == old_file_h->e_shnum)
 493     {
 494       if (noerror)
 495         return -1;
 496       else
 497         fatal ("Can't find .bss in %s.\n", file_name, 0);
 498     }
 499
 500   return idx;
 501 }
 502
 503 /* ****************************************************************
 504  * unexec
 505  *
 506  * driving logic.
 507  *
 508  * In ELF, this works by replacing the old .bss section with a new
 509  * .data section, and inserting an empty .bss immediately afterwards.
 510  *
 511  */
 512 void
 513 unexec (new_name, old_name, data_start, bss_start, entry_address)
 514      char *new_name, *old_name;
 515      unsigned data_start, bss_start, entry_address;
 516 {
 517   extern unsigned int bss_end;
 518   int new_file, old_file, new_file_size;
 519
 520   /* Pointers to the base of the image of the two files.  */
 521   caddr_t old_base, new_base;
 522
 523   /* Pointers to the file, program and section headers for the old and new
 524      files.  */
 525   Elf32_Ehdr *old_file_h, *new_file_h;
 526   Elf32_Phdr *old_program_h, *new_program_h;
 527   Elf32_Shdr *old_section_h, *new_section_h;
 528
 529   /* Point to the section name table in the old file.  */
 530   char *old_section_names;
 531
 532   Elf32_Addr old_bss_addr, new_bss_addr;
 533   Elf32_Word old_bss_size, new_data2_size;
 534   Elf32_Off  new_data2_offset;
 535   Elf32_Addr new_data2_addr;
 536   Elf32_Addr new_offsets_shift;
 537
 538   int n, nn, old_bss_index, old_data_index, new_data2_index;
 539   int old_mdebug_index;
 540   struct stat stat_buf;
 541
 542   /* Open the old file & map it into the address space.  */
 543
 544   old_file = open (old_name, O_RDONLY);
 545
 546   if (old_file < 0)
 547     fatal ("Can't open %s for reading: errno %d\n", old_name, errno);
 548
 549   if (fstat (old_file, &stat_buf) == -1)
 550     fatal ("Can't fstat(%s): errno %d\n", old_name, errno);
 551
 552   old_base = mmap (0, stat_buf.st_size, PROT_READ, MAP_SHARED, old_file, 0);
 553
 554   if (old_base == (caddr_t) -1)
 555     fatal ("Can't mmap(%s): errno %d\n", old_name, errno);
 556
 557 #ifdef DEBUG
 558   fprintf (stderr, "mmap(%s, %x) -> %x\n", old_name, stat_buf.st_size,
 559            old_base);
 560 #endif
 561
 562   /* Get pointers to headers & section names.  */
 563
 564   old_file_h = (Elf32_Ehdr *) old_base;
 565   old_program_h = (Elf32_Phdr *) ((byte *) old_base + old_file_h->e_phoff);
 566   old_section_h = (Elf32_Shdr *) ((byte *) old_base + old_file_h->e_shoff);
 567   old_section_names
 568     = (char *) old_base + OLD_SECTION_H (old_file_h->e_shstrndx).sh_offset;
 569
 570   /* Find the mdebug section, if any.  */
 571
 572   old_mdebug_index = find_section (".mdebug", old_section_names,
 573                                    old_name, old_file_h, old_section_h, 1);
 574
 575   /* Find the old .bss section. */
 576
 577   old_bss_index = find_section (".bss", old_section_names,
 578                                 old_name, old_file_h, old_section_h, 0);
 579
 580   /* Find the old .data section.  Figure out parameters of
 581      the new data2 and bss sections.  */
 582
 583   old_data_index = find_section (".data", old_section_names,
 584                                  old_name, old_file_h, old_section_h, 0);
 585
 586   old_bss_addr = OLD_SECTION_H (old_bss_index).sh_addr;
 587   old_bss_size = OLD_SECTION_H (old_bss_index).sh_size;
 588 #if defined(emacs) || !defined(DEBUG)
 589   bss_end = (unsigned int) sbrk (0);
 590   new_bss_addr = (Elf32_Addr) bss_end;
 591 #else
 592   new_bss_addr = old_bss_addr + old_bss_size + 0x1234;
 593 #endif
 594   new_data2_addr = old_bss_addr;
 595   new_data2_size = new_bss_addr - old_bss_addr;
 596   new_data2_offset  = OLD_SECTION_H (old_data_index).sh_offset +
 597     (new_data2_addr - OLD_SECTION_H (old_data_index).sh_addr);
 598   new_offsets_shift = new_bss_addr -
 599     ((old_bss_addr & ~0xfff) + ((old_bss_addr & 0xfff) ? 0x1000 : 0));
 600
 601 #ifdef DEBUG
 602   fprintf (stderr, "old_bss_index %d\n", old_bss_index);
 603   fprintf (stderr, "old_bss_addr %x\n", old_bss_addr);
 604   fprintf (stderr, "old_bss_size %x\n", old_bss_size);
 605   fprintf (stderr, "new_bss_addr %x\n", new_bss_addr);
 606   fprintf (stderr, "new_data2_addr %x\n", new_data2_addr);
 607   fprintf (stderr, "new_data2_size %x\n", new_data2_size);
 608   fprintf (stderr, "new_data2_offset %x\n", new_data2_offset);
 609   fprintf (stderr, "new_offsets_shift %x\n", new_offsets_shift);
 610 #endif
 611
 612   if ((unsigned) new_bss_addr < (unsigned) old_bss_addr + old_bss_size)
 613     fatal (".bss shrank when undumping???\n", 0, 0);
 614
 615   /* Set the output file to the right size and mmap it.  Set
 616      pointers to various interesting objects.  stat_buf still has
 617      old_file data.  */
 618
 619   new_file = open (new_name, O_RDWR | O_CREAT, 0666);
 620   if (new_file < 0)
 621     fatal ("Can't creat (%s): errno %d\n", new_name, errno);
 622
 623   new_file_size = stat_buf.st_size + old_file_h->e_shentsize + new_offsets_shift;
 624
 625   if (ftruncate (new_file, new_file_size))
 626     fatal ("Can't ftruncate (%s): errno %d\n", new_name, errno);
 627
 628   new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_SHARED,
 629                    new_file, 0);
 630
 631   if (new_base == (caddr_t) -1)
 632     fatal ("Can't mmap (%s): errno %d\n", new_name, errno);
 633
 634   new_file_h = (Elf32_Ehdr *) new_base;
 635   new_program_h = (Elf32_Phdr *) ((byte *) new_base + old_file_h->e_phoff);
 636   new_section_h
 637     = (Elf32_Shdr *) ((byte *) new_base + old_file_h->e_shoff
 638                       + new_offsets_shift);
 639
 640   /* Make our new file, program and section headers as copies of the
 641      originals.  */
 642
 643   memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
 644   memcpy (new_program_h, old_program_h,
 645           old_file_h->e_phnum * old_file_h->e_phentsize);
 646
 647   /* Modify the e_shstrndx if necessary. */
 648   PATCH_INDEX (new_file_h->e_shstrndx);
 649
 650   /* Fix up file header.  We'll add one section.  Section header is
 651      further away now.  */
 652
 653   new_file_h->e_shoff += new_offsets_shift;
 654   new_file_h->e_shnum += 1;
 655
 656 #ifdef DEBUG
 657   fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff);
 658   fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum);
 659   fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff);
 660   fprintf (stderr, "New section count %d\n", new_file_h->e_shnum);
 661 #endif
 662
 663   /* Fix up a new program header.  Extend the writable data segment so
 664      that the bss area is covered too. Find that segment by looking
 665      for a segment that ends just before the .bss area.  Make sure
 666      that no segments are above the new .data2.  Put a loop at the end
 667      to adjust the offset and address of any segment that is above
 668      data2, just in case we decide to allow this later.  */
 669
 670   for (n = new_file_h->e_phnum - 1; n >= 0; n--)
 671     {
 672       /* Compute maximum of all requirements for alignment of section.  */
 673       int alignment = (NEW_PROGRAM_H (n)).p_align;
 674       if ((OLD_SECTION_H (old_bss_index)).sh_addralign > alignment)
 675         alignment = OLD_SECTION_H (old_bss_index).sh_addralign;
 676
 677       /* Supposedly this condition is okay for the SGI.  */
 678 #if 0
 679       if (NEW_PROGRAM_H (n).p_vaddr + NEW_PROGRAM_H (n).p_filesz > old_bss_addr)
 680         fatal ("Program segment above .bss in %s\n", old_name, 0);
 681 #endif
 682
 683       if (NEW_PROGRAM_H (n).p_type == PT_LOAD
 684           && (round_up ((NEW_PROGRAM_H (n)).p_vaddr
 685                         + (NEW_PROGRAM_H (n)).p_filesz,
 686                         alignment)
 687               == round_up (old_bss_addr, alignment)))
 688         break;
 689     }
 690   if (n < 0)
 691     fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0);
 692
 693   NEW_PROGRAM_H (n).p_filesz += new_offsets_shift;
 694   NEW_PROGRAM_H (n).p_memsz = NEW_PROGRAM_H (n).p_filesz;
 695
 696 #if 1                           /* Maybe allow section after data2 - does this ever happen?  */
 697   for (n = new_file_h->e_phnum - 1; n >= 0; n--)
 698     {
 699       if (NEW_PROGRAM_H (n).p_vaddr
 700           && NEW_PROGRAM_H (n).p_vaddr >= new_data2_addr)
 701         NEW_PROGRAM_H (n).p_vaddr += new_offsets_shift - old_bss_size;
 702
 703       if (NEW_PROGRAM_H (n).p_offset >= new_data2_offset)
 704         NEW_PROGRAM_H (n).p_offset += new_offsets_shift;
 705     }
 706 #endif
 707
 708   /* Fix up section headers based on new .data2 section.  Any section
 709      whose offset or virtual address is after the new .data2 section
 710      gets its value adjusted.  .bss size becomes zero and new address
 711      is set.  data2 section header gets added by copying the existing
 712      .data header and modifying the offset, address and size.  */
 713   for (old_data_index = 1; old_data_index < old_file_h->e_shnum;
 714        old_data_index++)
 715     if (!strcmp (old_section_names + OLD_SECTION_H (old_data_index).sh_name,
 716                  ".data"))
 717       break;
 718   if (old_data_index == old_file_h->e_shnum)
 719     fatal ("Can't find .data in %s.\n", old_name, 0);
 720
 721   /* Walk through all section headers, insert the new data2 section right
 722      before the new bss section.  */
 723   for (n = 1, nn = 1; n < old_file_h->e_shnum; n++, nn++)
 724     {
 725       caddr_t src;
 726
 727       /* If it is bss section, insert the new data2 section before it.  */
 728       if (n == old_bss_index)
 729         {
 730           /* Steal the data section header for this data2 section.  */
 731           memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (old_data_index),
 732                   new_file_h->e_shentsize);
 733
 734           NEW_SECTION_H (nn).sh_addr = new_data2_addr;
 735           NEW_SECTION_H (nn).sh_offset = new_data2_offset;
 736           NEW_SECTION_H (nn).sh_size = new_data2_size;
 737           /* Use the bss section's alignment. This will assure that the
 738              new data2 section always be placed in the same spot as the old
 739              bss section by any other application.  */
 740           NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (n).sh_addralign;
 741
 742           /* Now copy over what we have in the memory now.  */
 743           memcpy (NEW_SECTION_H (nn).sh_offset + new_base,
 744                   (caddr_t) OLD_SECTION_H (n).sh_addr,
 745                   new_data2_size);
 746           nn++;
 747           memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n),
 748                   old_file_h->e_shentsize);
 749
 750           /* The new bss section's size is zero, and its file offset and virtual
 751              address should be off by NEW_OFFSETS_SHIFT.  */
 752           NEW_SECTION_H (nn).sh_offset += new_offsets_shift;
 753           NEW_SECTION_H (nn).sh_addr    = new_bss_addr;
 754           /* Let the new bss section address alignment be the same as the
 755              section address alignment followed the old bss section, so
 756              this section will be placed in exactly the same place.  */
 757           NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (nn).sh_addralign;
 758           NEW_SECTION_H (nn).sh_size = 0;
 759         }
 760       else
 761         memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n),
 762                 old_file_h->e_shentsize);
 763
 764       /* Any section that was original placed AFTER the bss
 765          section must now be adjusted by NEW_OFFSETS_SHIFT.  */
 766
 767       if (NEW_SECTION_H (nn).sh_offset >= new_data2_offset)
 768         NEW_SECTION_H (nn).sh_offset += new_offsets_shift;
 769
 770       /* If any section hdr refers to the section after the new .data
 771          section, make it refer to next one because we have inserted
 772          a new section in between.  */
 773
 774       PATCH_INDEX (NEW_SECTION_H (nn).sh_link);
 775       /* For symbol tables, info is a symbol table index,
 776          so don't change it.  */
 777       if (NEW_SECTION_H (nn).sh_type != SHT_SYMTAB
 778           && NEW_SECTION_H (nn).sh_type != SHT_DYNSYM)
 779         PATCH_INDEX (NEW_SECTION_H (nn).sh_info);
 780
 781       /* Now, start to copy the content of sections. */
 782       if (NEW_SECTION_H (nn).sh_type == SHT_NULL
 783           || NEW_SECTION_H (nn).sh_type == SHT_NOBITS)
 784         continue;
 785
 786       /* Write out the sections. .data and .data1 (and data2, called
 787          ".data" in the strings table) get copied from the current process
 788          instead of the old file.  */
 789       if (!strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".data")
 790           || !strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".data1")
 791           || !strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".got"))
 792         src = (caddr_t) OLD_SECTION_H (n).sh_addr;
 793       else
 794         src = old_base + OLD_SECTION_H (n).sh_offset;
 795
 796       memcpy (NEW_SECTION_H (nn).sh_offset + new_base, src,
 797               NEW_SECTION_H (nn).sh_size);
 798
 799       /* Adjust  the HDRR offsets in .mdebug and copy the
 800          line data if it's in its usual 'hole' in the object.
 801          Makes the new file debuggable with dbx.
 802          patches up two problems: the absolute file offsets
 803          in the HDRR record of .mdebug (see /usr/include/syms.h), and
 804          the ld bug that gets the line table in a hole in the
 805          elf file rather than in the .mdebug section proper.
 806          David Anderson. davea@sgi.com  Jan 16,1994.  */
 807       if (n == old_mdebug_index)
 808         {
 809 #define MDEBUGADJUST(__ct,__fileaddr)           \
 810   if (n_phdrr->__ct > 0)                        \
 811     {                                           \
 812       n_phdrr->__fileaddr += movement;          \
 813     }
 814
 815           HDRR * o_phdrr = (HDRR *)((byte *)old_base + OLD_SECTION_H (n).sh_offset);
 816           HDRR * n_phdrr = (HDRR *)((byte *)new_base + NEW_SECTION_H (nn).sh_offset);
 817           unsigned movement = new_offsets_shift;
 818
 819           MDEBUGADJUST (idnMax, cbDnOffset);
 820           MDEBUGADJUST (ipdMax, cbPdOffset);
 821           MDEBUGADJUST (isymMax, cbSymOffset);
 822           MDEBUGADJUST (ioptMax, cbOptOffset);
 823           MDEBUGADJUST (iauxMax, cbAuxOffset);
 824           MDEBUGADJUST (issMax, cbSsOffset);
 825           MDEBUGADJUST (issExtMax, cbSsExtOffset);
 826           MDEBUGADJUST (ifdMax, cbFdOffset);
 827           MDEBUGADJUST (crfd, cbRfdOffset);
 828           MDEBUGADJUST (iextMax, cbExtOffset);
 829           /* The Line Section, being possible off in a hole of the object,
 830              requires special handling.  */
 831           if (n_phdrr->cbLine > 0)
 832             {
 833               if (o_phdrr->cbLineOffset > (OLD_SECTION_H (n).sh_offset
 834                                            + OLD_SECTION_H (n).sh_size))
 835                 {
 836                   /* line data is in a hole in elf. do special copy and adjust
 837                      for this ld mistake.
 838                      */
 839                   n_phdrr->cbLineOffset += movement;
 840
 841                   memcpy (n_phdrr->cbLineOffset + new_base,
 842                           o_phdrr->cbLineOffset + old_base, n_phdrr->cbLine);
 843                 }
 844               else
 845                 {
 846                   /* somehow line data is in .mdebug as it is supposed to be.  */
 847                   MDEBUGADJUST (cbLine, cbLineOffset);
 848                 }
 849             }
 850         }
 851
 852       /* If it is the symbol table, its st_shndx field needs to be patched. */
 853       if (NEW_SECTION_H (nn).sh_type == SHT_SYMTAB
 854           || NEW_SECTION_H (nn).sh_type == SHT_DYNSYM)
 855         {
 856           Elf32_Shdr *spt = &NEW_SECTION_H (nn);
 857           unsigned int num = spt->sh_size / spt->sh_entsize;
 858           Elf32_Sym * sym = (Elf32_Sym *) (NEW_SECTION_H (nn).sh_offset
 859                                            + new_base);
 860           for (; num--; sym++)
 861             {
 862               if (sym->st_shndx == SHN_UNDEF
 863                   || sym->st_shndx == SHN_ABS
 864                   || sym->st_shndx == SHN_COMMON)
 865                 continue;
 866
 867               PATCH_INDEX (sym->st_shndx);
 868             }
 869         }
 870     }
 871
 872   /* Close the files and make the new file executable.  */
 873
 874   if (close (old_file))
 875     fatal ("Can't close (%s): errno %d\n", old_name, errno);
 876
 877   if (close (new_file))
 878     fatal ("Can't close (%s): errno %d\n", new_name, errno);
 879
 880   if (stat (new_name, &stat_buf) == -1)
 881     fatal ("Can't stat (%s): errno %d\n", new_name, errno);
 882
 883   n = umask (777);
 884   umask (n);
 885   stat_buf.st_mode |= 0111 & ~n;
 886   if (chmod (new_name, stat_buf.st_mode) == -1)
 887     fatal ("Can't chmod (%s): errno %d\n", new_name, errno);
 888 }