src/unexelf1.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 <sys/mman.h>
 425
 426 #ifdef __alpha__
 427 # include <sym.h>       /* get COFF debugging symbol table declaration */
 428 #endif
 429
 430 #if __GNU_LIBRARY__ - 0 >= 6
 431 # include <link.h>      /* get ElfW etc */
 432 #endif
 433
 434 #ifndef ElfW
 435 # ifdef __STDC__
 436 #  define ElfW(type)    Elf32_##type
 437 # else
 438 #  define ElfW(type)    Elf32_/**/type
 439 # endif
 440 #endif
 441
 442 #ifndef emacs
 443 #define fatal(a, b, c) fprintf (stderr, a, b, c), exit (1)
 444 #else
 445 #include <config.h>
 446 extern void fatal (char *, ...);
 447 #endif
 448
 449 #ifndef ELF_BSS_SECTION_NAME
 450 #define ELF_BSS_SECTION_NAME ".bss"
 451 #endif
 452
 453 /* Get the address of a particular section or program header entry,
 454  * accounting for the size of the entries.
 455  */
 456 /*
 457    On PPC Reference Platform running Solaris 2.5.1
 458    the plt section is also of type NOBI like the bss section.
 459    (not really stored) and therefore sections after the bss
 460    section start at the plt offset. The plt section is always
 461    the one just before the bss section.
 462    Thus, we modify the test from
 463       if (NEW_SECTION_H (nn).sh_offset >= new_data2_offset)
 464    to
 465       if (NEW_SECTION_H (nn).sh_offset >=
 466                OLD_SECTION_H (old_bss_index-1).sh_offset)
 467    This is just a hack. We should put the new data section
 468    before the .plt section.
 469    And we should not have this routine at all but use
 470    the libelf library to read the old file and create the new
 471    file.
 472    The changed code is minimal and depends on prep set in m/prep.h
 473    Erik Deumens
 474    Quantum Theory Project
 475    University of Florida
 476    deumens@qtp.ufl.edu
 477    Apr 23, 1996
 478    */
 479
 480 #define OLD_SECTION_H(n) \
 481      (*(ElfW(Shdr) *) ((byte *) old_section_h + old_file_h->e_shentsize * (n)))
 482 #define NEW_SECTION_H(n) \
 483      (*(ElfW(Shdr) *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
 484 #define OLD_PROGRAM_H(n) \
 485      (*(ElfW(Phdr) *) ((byte *) old_program_h + old_file_h->e_phentsize * (n)))
 486 #define NEW_PROGRAM_H(n) \
 487      (*(ElfW(Phdr) *) ((byte *) new_program_h + new_file_h->e_phentsize * (n)))
 488
 489 #define PATCH_INDEX(n) \
 490   do { \
 491          if ((int) (n) >= old_bss_index) \
 492            (n)++; } while (0)
 493 typedef unsigned char byte;
 494
 495 /* Round X up to a multiple of Y.  */
 496
 497 int
 498 round_up (x, y)
 499      int x, y;
 500 {
 501   int rem = x % y;
 502   if (rem == 0)
 503     return x;
 504   return x - rem + y;
 505 }
 506
 507 /* ****************************************************************
 508  * unexec
 509  *
 510  * driving logic.
 511  *
 512  * In ELF, this works by replacing the old .bss section with a new
 513  * .data section, and inserting an empty .bss immediately afterwards.
 514  *
 515  */
 516 void
 517 unexec (new_name, old_name, data_start, bss_start, entry_address)
 518      char *new_name, *old_name;
 519      unsigned data_start, bss_start, entry_address;
 520 {
 521   int new_file, old_file, new_file_size;
 522
 523   /* Pointers to the base of the image of the two files. */
 524   caddr_t old_base, new_base;
 525
 526   /* Pointers to the file, program and section headers for the old and new
 527    * files.
 528    */
 529   ElfW(Ehdr) *old_file_h, *new_file_h;
 530   ElfW(Phdr) *old_program_h, *new_program_h;
 531   ElfW(Shdr) *old_section_h, *new_section_h;
 532
 533   /* Point to the section name table in the old file */
 534   char *old_section_names;
 535
 536   ElfW(Addr) old_bss_addr, new_bss_addr;
 537   ElfW(Word) old_bss_size, new_data2_size;
 538   ElfW(Off)  new_data2_offset;
 539   ElfW(Addr) new_data2_addr;
 540
 541   int n, nn, old_bss_index, old_data_index, new_data2_index;
 542   struct stat stat_buf;
 543
 544   /* Open the old file & map it into the address space. */
 545
 546   old_file = open (old_name, O_RDONLY);
 547
 548   if (old_file < 0)
 549     fatal ("Can't open %s for reading: errno %d\n", old_name, errno);
 550
 551   if (fstat (old_file, &stat_buf) == -1)
 552     fatal ("Can't fstat (%s): errno %d\n", old_name, errno);
 553
 554   old_base = mmap (0, stat_buf.st_size, PROT_READ, MAP_SHARED, old_file, 0);
 555
 556   if (old_base == (caddr_t) -1)
 557     fatal ("Can't mmap (%s): errno %d\n", old_name, errno);
 558
 559 #ifdef DEBUG
 560   fprintf (stderr, "mmap (%s, %x) -> %x\n", old_name, stat_buf.st_size,
 561            old_base);
 562 #endif
 563
 564   /* Get pointers to headers & section names */
 565
 566   old_file_h = (ElfW(Ehdr) *) old_base;
 567   old_program_h = (ElfW(Phdr) *) ((byte *) old_base + old_file_h->e_phoff);
 568   old_section_h = (ElfW(Shdr) *) ((byte *) old_base + old_file_h->e_shoff);
 569   old_section_names = (char *) old_base
 570     + OLD_SECTION_H (old_file_h->e_shstrndx).sh_offset;
 571
 572   /* Find the old .bss section.  Figure out parameters of the new
 573    * data2 and bss sections.
 574    */
 575
 576   for (old_bss_index = 1; old_bss_index < (int) old_file_h->e_shnum;
 577        old_bss_index++)
 578     {
 579 #ifdef DEBUG
 580       fprintf (stderr, "Looking for .bss - found %s\n",
 581                old_section_names + OLD_SECTION_H (old_bss_index).sh_name);
 582 #endif
 583       if (!strcmp (old_section_names + OLD_SECTION_H (old_bss_index).sh_name,
 584                    ELF_BSS_SECTION_NAME))
 585         break;
 586     }
 587   if (old_bss_index == old_file_h->e_shnum)
 588     fatal ("Can't find .bss in %s.\n", old_name, 0);
 589
 590   old_bss_addr = OLD_SECTION_H (old_bss_index).sh_addr;
 591   old_bss_size = OLD_SECTION_H (old_bss_index).sh_size;
 592 #if defined(emacs) || !defined(DEBUG)
 593   new_bss_addr = (ElfW(Addr)) sbrk (0);
 594 #else
 595   new_bss_addr = old_bss_addr + old_bss_size + 0x1234;
 596 #endif
 597   new_data2_addr = old_bss_addr;
 598   new_data2_size = new_bss_addr - old_bss_addr;
 599   new_data2_offset = OLD_SECTION_H (old_bss_index).sh_offset;
 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 #endif
 610
 611   if ((unsigned) new_bss_addr < (unsigned) old_bss_addr + old_bss_size)
 612     fatal (".bss shrank when undumping???\n", 0, 0);
 613
 614   /* Set the output file to the right size and mmap it.  Set
 615    * pointers to various interesting objects.  stat_buf still has
 616    * old_file data.
 617    */
 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_data2_size;
 624
 625   if (ftruncate (new_file, new_file_size))
 626     fatal ("Can't ftruncate (%s): errno %d\n", new_name, errno);
 627
 628 #ifdef UNEXEC_USE_MAP_PRIVATE
 629   new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
 630                    new_file, 0);
 631 #else
 632   new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_SHARED,
 633                    new_file, 0);
 634 #endif
 635
 636   if (new_base == (caddr_t) -1)
 637     fatal ("Can't mmap (%s): errno %d\n", new_name, errno);
 638
 639   new_file_h = (ElfW(Ehdr) *) new_base;
 640   new_program_h = (ElfW(Phdr) *) ((byte *) new_base + old_file_h->e_phoff);
 641   new_section_h = (ElfW(Shdr) *)
 642     ((byte *) new_base + old_file_h->e_shoff + new_data2_size);
 643
 644   /* Make our new file, program and section headers as copies of the
 645    * originals.
 646    */
 647
 648   memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
 649   memcpy (new_program_h, old_program_h,
 650           old_file_h->e_phnum * old_file_h->e_phentsize);
 651
 652   /* Modify the e_shstrndx if necessary. */
 653   PATCH_INDEX (new_file_h->e_shstrndx);
 654
 655   /* Fix up file header.  We'll add one section.  Section header is
 656    * further away now.
 657    */
 658
 659   new_file_h->e_shoff += new_data2_size;
 660   new_file_h->e_shnum += 1;
 661
 662 #ifdef DEBUG
 663   fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff);
 664   fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum);
 665   fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff);
 666   fprintf (stderr, "New section count %d\n", new_file_h->e_shnum);
 667 #endif
 668
 669   /* Fix up a new program header.  Extend the writable data segment so
 670    * that the bss area is covered too. Find that segment by looking
 671    * for a segment that ends just before the .bss area.  Make sure
 672    * that no segments are above the new .data2.  Put a loop at the end
 673    * to adjust the offset and address of any segment that is above
 674    * data2, just in case we decide to allow this later.
 675    */
 676
 677   for (n = new_file_h->e_phnum - 1; n >= 0; n--)
 678     {
 679       /* Compute maximum of all requirements for alignment of section.  */
 680       int alignment = (NEW_PROGRAM_H (n)).p_align;
 681       if ((OLD_SECTION_H (old_bss_index)).sh_addralign > alignment)
 682         alignment = OLD_SECTION_H (old_bss_index).sh_addralign;
 683
 684       if (NEW_PROGRAM_H (n).p_vaddr + NEW_PROGRAM_H (n).p_filesz > old_bss_addr)
 685         fatal ("Program segment above .bss in %s\n", old_name, 0);
 686
 687       if (NEW_PROGRAM_H (n).p_type == PT_LOAD
 688           && (round_up ((NEW_PROGRAM_H (n)).p_vaddr
 689                         + (NEW_PROGRAM_H (n)).p_filesz,
 690                         alignment)
 691               == round_up (old_bss_addr, alignment)))
 692         break;
 693     }
 694   if (n < 0)
 695     fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0);
 696
 697   NEW_PROGRAM_H (n).p_filesz += new_data2_size;
 698   NEW_PROGRAM_H (n).p_memsz = NEW_PROGRAM_H (n).p_filesz;
 699
 700 #if 0 /* Maybe allow section after data2 - does this ever happen? */
 701   for (n = new_file_h->e_phnum - 1; n >= 0; n--)
 702     {
 703       if (NEW_PROGRAM_H (n).p_vaddr
 704           && NEW_PROGRAM_H (n).p_vaddr >= new_data2_addr)
 705         NEW_PROGRAM_H (n).p_vaddr += new_data2_size - old_bss_size;
 706
 707       if (NEW_PROGRAM_H (n).p_offset >= new_data2_offset)
 708         NEW_PROGRAM_H (n).p_offset += new_data2_size;
 709     }
 710 #endif
 711
 712   /* Fix up section headers based on new .data2 section.  Any section
 713    * whose offset or virtual address is after the new .data2 section
 714    * gets its value adjusted.  .bss size becomes zero and new address
 715    * is set.  data2 section header gets added by copying the existing
 716    * .data header and modifying the offset, address and size.
 717    */
 718   for (old_data_index = 1; old_data_index < (int) old_file_h->e_shnum;
 719        old_data_index++)
 720     if (!strcmp (old_section_names + OLD_SECTION_H (old_data_index).sh_name,
 721                  ".data"))
 722       break;
 723   if (old_data_index == old_file_h->e_shnum)
 724     fatal ("Can't find .data in %s.\n", old_name, 0);
 725
 726   /* Walk through all section headers, insert the new data2 section right
 727      before the new bss section. */
 728   for (n = 1, nn = 1; n < (int) old_file_h->e_shnum; n++, nn++)
 729     {
 730       caddr_t src;
 731       /* If it is bss section, insert the new data2 section before it. */
 732       if (n == old_bss_index)
 733         {
 734           /* Steal the data section header for this data2 section. */
 735           memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (old_data_index),
 736                   new_file_h->e_shentsize);
 737
 738           NEW_SECTION_H (nn).sh_addr = new_data2_addr;
 739           NEW_SECTION_H (nn).sh_offset = new_data2_offset;
 740           NEW_SECTION_H (nn).sh_size = new_data2_size;
 741           /* Use the bss section's alignment. This will assure that the
 742              new data2 section always be placed in the same spot as the old
 743              bss section by any other application. */
 744           NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (n).sh_addralign;
 745
 746           /* Now copy over what we have in the memory now. */
 747           memcpy (NEW_SECTION_H (nn).sh_offset + new_base,
 748                   (caddr_t) OLD_SECTION_H (n).sh_addr,
 749                   new_data2_size);
 750           nn++;
 751         }
 752
 753       memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n),
 754               old_file_h->e_shentsize);
 755
 756       /* The new bss section's size is zero, and its file offset and virtual
 757          address should be off by NEW_DATA2_SIZE. */
 758       if (n == old_bss_index)
 759         {
 760           /* NN should be `old_bss_index + 1' at this point. */
 761           NEW_SECTION_H (nn).sh_offset += new_data2_size;
 762           NEW_SECTION_H (nn).sh_addr += new_data2_size;
 763           /* Let the new bss section address alignment be the same as the
 764              section address alignment followed the old bss section, so
 765              this section will be placed in exactly the same place. */
 766           NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (nn).sh_addralign;
 767           NEW_SECTION_H (nn).sh_size = 0;
 768         }
 769       else
 770         {
 771           /* Any section that was original placed AFTER the bss
 772              section should now be off by NEW_DATA2_SIZE. */
 773 #ifdef SOLARIS_POWERPC
 774           /* On PPC Reference Platform running Solaris 2.5.1
 775              the plt section is also of type NOBI like the bss section.
 776              (not really stored) and therefore sections after the bss
 777              section start at the plt offset. The plt section is always
 778              the one just before the bss section.
 779              It would be better to put the new data section before
 780              the .plt section, or use libelf instead.
 781              Erik Deumens, deumens@qtp.ufl.edu.  */
 782           if (NEW_SECTION_H (nn).sh_offset
 783               >= OLD_SECTION_H (old_bss_index-1).sh_offset)
 784             NEW_SECTION_H (nn).sh_offset += new_data2_size;
 785 #else
 786           if (round_up (NEW_SECTION_H (nn).sh_offset,
 787                         OLD_SECTION_H (old_bss_index).sh_addralign)
 788               >= new_data2_offset)
 789             NEW_SECTION_H (nn).sh_offset += new_data2_size;
 790 #endif
 791           /* Any section that was originally placed after the section
 792              header table should now be off by the size of one section
 793              header table entry.  */
 794           if (NEW_SECTION_H (nn).sh_offset > new_file_h->e_shoff)
 795             NEW_SECTION_H (nn).sh_offset += new_file_h->e_shentsize;
 796         }
 797
 798       /* If any section hdr refers to the section after the new .data
 799          section, make it refer to next one because we have inserted
 800          a new section in between.  */
 801
 802       PATCH_INDEX (NEW_SECTION_H (nn).sh_link);
 803       /* For symbol tables, info is a symbol table index,
 804          so don't change it.  */
 805       if (NEW_SECTION_H (nn).sh_type != SHT_SYMTAB
 806           && NEW_SECTION_H (nn).sh_type != SHT_DYNSYM)
 807         PATCH_INDEX (NEW_SECTION_H (nn).sh_info);
 808
 809       /* Now, start to copy the content of sections.  */
 810       if (NEW_SECTION_H (nn).sh_type == SHT_NULL
 811           || NEW_SECTION_H (nn).sh_type == SHT_NOBITS)
 812         continue;
 813
 814       /* Write out the sections. .data and .data1 (and data2, called
 815          ".data" in the strings table) get copied from the current process
 816          instead of the old file.  */
 817       if (!strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".data")
 818           || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name),
 819                       ".data1"))
 820         src = (caddr_t) OLD_SECTION_H (n).sh_addr;
 821       else
 822         src = old_base + OLD_SECTION_H (n).sh_offset;
 823
 824       memcpy (NEW_SECTION_H (nn).sh_offset + new_base, src,
 825               NEW_SECTION_H (nn).sh_size);
 826
 827 #ifdef __alpha__
 828       /* Update Alpha COFF symbol table: */
 829       if (strcmp (old_section_names + OLD_SECTION_H (n).sh_name, ".mdebug")
 830           == 0)
 831         {
 832           pHDRR symhdr = (pHDRR) (NEW_SECTION_H (nn).sh_offset + new_base);
 833
 834           symhdr->cbLineOffset += new_data2_size;
 835           symhdr->cbDnOffset += new_data2_size;
 836           symhdr->cbPdOffset += new_data2_size;
 837           symhdr->cbSymOffset += new_data2_size;
 838           symhdr->cbOptOffset += new_data2_size;
 839           symhdr->cbAuxOffset += new_data2_size;
 840           symhdr->cbSsOffset += new_data2_size;
 841           symhdr->cbSsExtOffset += new_data2_size;
 842           symhdr->cbFdOffset += new_data2_size;
 843           symhdr->cbRfdOffset += new_data2_size;
 844           symhdr->cbExtOffset += new_data2_size;
 845         }
 846 #endif /* __alpha__ */
 847
 848       /* If it is the symbol table, its st_shndx field needs to be patched.  */
 849       if (NEW_SECTION_H (nn).sh_type == SHT_SYMTAB
 850           || NEW_SECTION_H (nn).sh_type == SHT_DYNSYM)
 851         {
 852           ElfW(Shdr) *spt = &NEW_SECTION_H (nn);
 853           unsigned int num = spt->sh_size / spt->sh_entsize;
 854           ElfW(Sym) * sym = (ElfW(Sym) *) (NEW_SECTION_H (nn).sh_offset +
 855                                            new_base);
 856           for (; num--; sym++)
 857             {
 858               if ((sym->st_shndx == SHN_UNDEF)
 859                   || (sym->st_shndx == SHN_ABS)
 860                   || (sym->st_shndx == SHN_COMMON))
 861                 continue;
 862
 863               PATCH_INDEX (sym->st_shndx);
 864             }
 865         }
 866     }
 867
 868   /* Update the symbol values of _edata and _end.  */
 869   for (n = new_file_h->e_shnum - 1; n; n--)
 870     {
 871       byte *symnames;
 872       ElfW(Sym) *symp, *symendp;
 873
 874       if (NEW_SECTION_H (n).sh_type != SHT_DYNSYM
 875           && NEW_SECTION_H (n).sh_type != SHT_SYMTAB)
 876         continue;
 877
 878       symnames = ((byte *) new_base
 879                   + NEW_SECTION_H (NEW_SECTION_H (n).sh_link).sh_offset);
 880       symp = (ElfW(Sym) *) (NEW_SECTION_H (n).sh_offset + new_base);
 881       symendp = (ElfW(Sym) *) ((byte *)symp + NEW_SECTION_H (n).sh_size);
 882
 883       for (; symp < symendp; symp ++)
 884         if (strcmp ((char *) (symnames + symp->st_name), "_end") == 0
 885             || strcmp ((char *) (symnames + symp->st_name), "_edata") == 0)
 886           memcpy (&symp->st_value, &new_bss_addr, sizeof (new_bss_addr));
 887     }
 888
 889   /* This loop seeks out relocation sections for the data section, so
 890      that it can undo relocations performed by the runtime linker.  */
 891   for (n = new_file_h->e_shnum - 1; n; n--)
 892     {
 893       ElfW(Shdr) section = NEW_SECTION_H (n);
 894       switch (section.sh_type) {
 895       default:
 896         break;
 897       case SHT_REL:
 898       case SHT_RELA:
 899         /* This code handles two different size structs, but there should
 900            be no harm in that provided that r_offset is always the first
 901            member.  */
 902         nn = section.sh_info;
 903         if (!strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data")
 904             || !strcmp ((old_section_names + NEW_SECTION_H (nn).sh_name),
 905                         ".data1"))
 906           {
 907             ElfW(Addr) offset = NEW_SECTION_H (nn).sh_addr -
 908               NEW_SECTION_H (nn).sh_offset;
 909             caddr_t reloc = old_base + section.sh_offset, end;
 910             for (end = reloc + section.sh_size; reloc < end;
 911                  reloc += section.sh_entsize)
 912               {
 913                 ElfW(Addr) addr = ((ElfW(Rel) *) reloc)->r_offset - offset;
 914 #ifdef __alpha__
 915                 /* The Alpha ELF binutils currently have a bug that
 916                    sometimes results in relocs that contain all
 917                    zeroes.  Work around this for now...  */
 918                 if (((ElfW(Rel) *) reloc)->r_offset == 0)
 919                     continue;
 920 #endif
 921                 memcpy (new_base + addr, old_base + addr, sizeof(ElfW(Addr)));
 922               }
 923           }
 924         break;
 925       }
 926     }
 927
 928 #ifdef UNEXEC_USE_MAP_PRIVATE
 929   if (lseek (new_file, 0, SEEK_SET) == -1)
 930     fatal ("Can't rewind (%s): errno %d\n", new_name, errno);
 931
 932   if (write (new_file, new_base, new_file_size) != new_file_size)
 933     fatal ("Can't write (%s): errno %d\n", new_name, errno);
 934 #endif
 935
 936   /* Close the files and make the new file executable.  */
 937
 938   if (close (old_file))
 939     fatal ("Can't close (%s): errno %d\n", old_name, errno);
 940
 941   if (close (new_file))
 942     fatal ("Can't close (%s): errno %d\n", new_name, errno);
 943
 944   if (stat (new_name, &stat_buf) == -1)
 945     fatal ("Can't stat (%s): errno %d\n", new_name, errno);
 946
 947   n = umask (777);
 948   umask (n);
 949   stat_buf.st_mode |= 0111 & ~n;
 950   if (chmod (new_name, stat_buf.st_mode) == -1)
 951     fatal ("Can't chmod (%s): errno %d\n", new_name, errno);
 952 }