src/unexelf.c

   1 /* Copyright (C) 1985, 1986, 1987, 1988, 1990, 1992
   2    Free Software Foundation, Inc.
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2, or (at your option)
   7     any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18 In other words, you are welcome to use, share and improve this program.
  19 You are forbidden to forbid anyone else to use, share and improve
  20 what you give them.   Help stamp out software-hoarding!  */
  21
  22
  23 /*
  24  * unexec.c - Convert a running program into an a.out file.
  25  *
  26  * Author:      Spencer W. Thomas
  27  *              Computer Science Dept.
  28  *              University of Utah
  29  * Date:        Tue Mar  2 1982
  30  * Modified heavily since then.
  31  *
  32  * Synopsis:
  33  *      unexec (new_name, a_name, data_start, bss_start, entry_address)
  34  *      char *new_name, *a_name;
  35  *      unsigned data_start, bss_start, entry_address;
  36  *
  37  * Takes a snapshot of the program and makes an a.out format file in the
  38  * file named by the string argument new_name.
  39  * If a_name is non-NULL, the symbol table will be taken from the given file.
  40  * On some machines, an existing a_name file is required.
  41  *
  42  * The boundaries within the a.out file may be adjusted with the data_start
  43  * and bss_start arguments.  Either or both may be given as 0 for defaults.
  44  *
  45  * Data_start gives the boundary between the text segment and the data
  46  * segment of the program.  The text segment can contain shared, read-only
  47  * program code and literal data, while the data segment is always unshared
  48  * and unprotected.  Data_start gives the lowest unprotected address.
  49  * The value you specify may be rounded down to a suitable boundary
  50  * as required by the machine you are using.
  51  *
  52  * Specifying zero for data_start means the boundary between text and data
  53  * should not be the same as when the program was loaded.
  54  * If NO_REMAP is defined, the argument data_start is ignored and the
  55  * segment boundaries are never changed.
  56  *
  57  * Bss_start indicates how much of the data segment is to be saved in the
  58  * a.out file and restored when the program is executed.  It gives the lowest
  59  * unsaved address, and is rounded up to a page boundary.  The default when 0
  60  * is given assumes that the entire data segment is to be stored, including
  61  * the previous data and bss as well as any additional storage allocated with
  62  * break (2).
  63  *
  64  * The new file is set up to start at entry_address.
  65  *
  66  * If you make improvements I'd like to get them too.
  67  * harpo!utah-cs!thomas, thomas@Utah-20
  68  *
  69  */
  70
  71 /* Even more heavily modified by james@bigtex.cactus.org of Dell Computer Co.
  72  * ELF support added.
  73  *
  74  * Basic theory: the data space of the running process needs to be
  75  * dumped to the output file.  Normally we would just enlarge the size
  76  * of .data, scooting everything down.  But we can't do that in ELF,
  77  * because there is often something between the .data space and the
  78  * .bss space.
  79  *
  80  * In the temacs dump below, notice that the Global Offset Table
  81  * (.got) and the Dynamic link data (.dynamic) come between .data1 and
  82  * .bss.  It does not work to overlap .data with these fields.
  83  *
  84  * The solution is to create a new .data segment.  This segment is
  85  * filled with data from the current process.  Since the contents of
  86  * various sections refer to sections by index, the new .data segment
  87  * is made the last in the table to avoid changing any existing index.
  88
  89  * This is an example of how the section headers are changed.  "Addr"
  90  * is a process virtual address.  "Offset" is a file offset.
  91
  92 raid:/nfs/raid/src/dist-18.56/src> dump -h temacs
  93
  94 temacs:
  95
  96            **** SECTION HEADER TABLE ****
  97 [No]    Type    Flags   Addr         Offset       Size          Name
  98         Link    Info    Adralgn      Entsize
  99
 100 [1]     1       2       0x80480d4    0xd4         0x13          .interp
 101         0       0       0x1          0
 102
 103 [2]     5       2       0x80480e8    0xe8         0x388         .hash
 104         3       0       0x4          0x4
 105
 106 [3]     11      2       0x8048470    0x470        0x7f0         .dynsym
 107         4       1       0x4          0x10
 108
 109 [4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
 110         0       0       0x1          0
 111
 112 [5]     9       2       0x8049010    0x1010       0x338         .rel.plt
 113         3       7       0x4          0x8
 114
 115 [6]     1       6       0x8049348    0x1348       0x3           .init
 116         0       0       0x4          0
 117
 118 [7]     1       6       0x804934c    0x134c       0x680         .plt
 119         0       0       0x4          0x4
 120
 121 [8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
 122         0       0       0x4          0
 123
 124 [9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
 125         0       0       0x4          0
 126
 127 [10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
 128         0       0       0x4          0
 129
 130 [11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
 131         0       0       0x4          0
 132
 133 [12]    1       3       0x8088330    0x3f330      0x20afc       .data
 134         0       0       0x4          0
 135
 136 [13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
 137         0       0       0x4          0
 138
 139 [14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
 140         0       0       0x4          0x4
 141
 142 [15]    6       3       0x80a9874    0x60874      0x80          .dynamic
 143         4       0       0x4          0x8
 144
 145 [16]    8       3       0x80a98f4    0x608f4      0x449c        .bss
 146         0       0       0x4          0
 147
 148 [17]    2       0       0            0x608f4      0x9b90        .symtab
 149         18      371     0x4          0x10
 150
 151 [18]    3       0       0            0x6a484      0x8526        .strtab
 152         0       0       0x1          0
 153
 154 [19]    3       0       0            0x729aa      0x93          .shstrtab
 155         0       0       0x1          0
 156
 157 [20]    1       0       0            0x72a3d      0x68b7        .comment
 158         0       0       0x1          0
 159
 160 raid:/nfs/raid/src/dist-18.56/src> dump -h xemacs
 161
 162 xemacs:
 163
 164            **** SECTION HEADER TABLE ****
 165 [No]    Type    Flags   Addr         Offset       Size          Name
 166         Link    Info    Adralgn      Entsize
 167
 168 [1]     1       2       0x80480d4    0xd4         0x13          .interp
 169         0       0       0x1          0
 170
 171 [2]     5       2       0x80480e8    0xe8         0x388         .hash
 172         3       0       0x4          0x4
 173
 174 [3]     11      2       0x8048470    0x470        0x7f0         .dynsym
 175         4       1       0x4          0x10
 176
 177 [4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
 178         0       0       0x1          0
 179
 180 [5]     9       2       0x8049010    0x1010       0x338         .rel.plt
 181         3       7       0x4          0x8
 182
 183 [6]     1       6       0x8049348    0x1348       0x3           .init
 184         0       0       0x4          0
 185
 186 [7]     1       6       0x804934c    0x134c       0x680         .plt
 187         0       0       0x4          0x4
 188
 189 [8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
 190         0       0       0x4          0
 191
 192 [9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
 193         0       0       0x4          0
 194
 195 [10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
 196         0       0       0x4          0
 197
 198 [11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
 199         0       0       0x4          0
 200
 201 [12]    1       3       0x8088330    0x3f330      0x20afc       .data
 202         0       0       0x4          0
 203
 204 [13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
 205         0       0       0x4          0
 206
 207 [14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
 208         0       0       0x4          0x4
 209
 210 [15]    6       3       0x80a9874    0x60874      0x80          .dynamic
 211         4       0       0x4          0x8
 212
 213 [16]    8       3       0x80c6800    0x7d800      0             .bss
 214         0       0       0x4          0
 215
 216 [17]    2       0       0            0x7d800      0x9b90        .symtab
 217         18      371     0x4          0x10
 218
 219 [18]    3       0       0            0x87390      0x8526        .strtab
 220         0       0       0x1          0
 221
 222 [19]    3       0       0            0x8f8b6      0x93          .shstrtab
 223         0       0       0x1          0
 224
 225 [20]    1       0       0            0x8f949      0x68b7        .comment
 226         0       0       0x1          0
 227
 228 [21]    1       3       0x80a98f4    0x608f4      0x1cf0c       .data
 229         0       0       0x4          0
 230
 231  * This is an example of how the file header is changed.  "Shoff" is
 232  * the section header offset within the file.  Since that table is
 233  * after the new .data section, it is moved.  "Shnum" is the number of
 234  * sections, which we increment.
 235  *
 236  * "Phoff" is the file offset to the program header.  "Phentsize" and
 237  * "Shentsz" are the program and section header entries sizes respectively.
 238  * These can be larger than the apparent struct sizes.
 239
 240 raid:/nfs/raid/src/dist-18.56/src> dump -f temacs
 241
 242 temacs:
 243
 244                     **** ELF HEADER ****
 245 Class        Data       Type         Machine     Version
 246 Entry        Phoff      Shoff        Flags       Ehsize
 247 Phentsize    Phnum      Shentsz      Shnum       Shstrndx
 248
 249 1            1          2            3           1
 250 0x80499cc    0x34       0x792f4      0           0x34
 251 0x20         5          0x28         21          19
 252
 253 raid:/nfs/raid/src/dist-18.56/src> dump -f xemacs
 254
 255 xemacs:
 256
 257                     **** ELF HEADER ****
 258 Class        Data       Type         Machine     Version
 259 Entry        Phoff      Shoff        Flags       Ehsize
 260 Phentsize    Phnum      Shentsz      Shnum       Shstrndx
 261
 262 1            1          2            3           1
 263 0x80499cc    0x34       0x96200      0           0x34
 264 0x20         5          0x28         22          19
 265
 266  * These are the program headers.  "Offset" is the file offset to the
 267  * segment.  "Vaddr" is the memory load address.  "Filesz" is the
 268  * segment size as it appears in the file, and "Memsz" is the size in
 269  * memory.  Below, the third segment is the code and the fourth is the
 270  * data: the difference between Filesz and Memsz is .bss
 271
 272 raid:/nfs/raid/src/dist-18.56/src> dump -o temacs
 273
 274 temacs:
 275  ***** PROGRAM EXECUTION HEADER *****
 276 Type        Offset      Vaddr       Paddr
 277 Filesz      Memsz       Flags       Align
 278
 279 6           0x34        0x8048034   0
 280 0xa0        0xa0        5           0
 281
 282 3           0xd4        0           0
 283 0x13        0           4           0
 284
 285 1           0x34        0x8048034   0
 286 0x3f2f9     0x3f2f9     5           0x1000
 287
 288 1           0x3f330     0x8088330   0
 289 0x215c4     0x25a60     7           0x1000
 290
 291 2           0x60874     0x80a9874   0
 292 0x80        0           7           0
 293
 294 raid:/nfs/raid/src/dist-18.56/src> dump -o xemacs
 295
 296 xemacs:
 297  ***** PROGRAM EXECUTION HEADER *****
 298 Type        Offset      Vaddr       Paddr
 299 Filesz      Memsz       Flags       Align
 300
 301 6           0x34        0x8048034   0
 302 0xa0        0xa0        5           0
 303
 304 3           0xd4        0           0
 305 0x13        0           4           0
 306
 307 1           0x34        0x8048034   0
 308 0x3f2f9     0x3f2f9     5           0x1000
 309
 310 1           0x3f330     0x8088330   0
 311 0x3e4d0     0x3e4d0     7           0x1000
 312
 313 2           0x60874     0x80a9874   0
 314 0x80        0           7           0
 315
 316
 317  */
 318 \f
 319 /* Modified by wtien@urbana.mcd.mot.com of Motorola Inc.
 320  *
 321  * The above mechanism does not work if the unexeced ELF file is being
 322  * re-layout by other applications (such as `strip'). All the applications
 323  * that re-layout the internal of ELF will layout all sections in ascending
 324  * order of their file offsets. After the re-layout, the data2 section will
 325  * still be the LAST section in the section header vector, but its file offset
 326  * is now being pushed far away down, and causes part of it not to be mapped
 327  * in (ie. not covered by the load segment entry in PHDR vector), therefore
 328  * causes the new binary to fail.
 329  *
 330  * The solution is to modify the unexec algorithm to insert the new data2
 331  * section header right before the new bss section header, so their file
 332  * offsets will be in the ascending order. Since some of the section's (all
 333  * sections AFTER the bss section) indexes are now changed, we also need to
 334  * modify some fields to make them point to the right sections. This is done
 335  * by macro PATCH_INDEX. All the fields that need to be patched are:
 336  *
 337  * 1. ELF header e_shstrndx field.
 338  * 2. section header sh_link and sh_info field.
 339  * 3. symbol table entry st_shndx field.
 340  *
 341  * The above example now should look like:
 342
 343            **** SECTION HEADER TABLE ****
 344 [No]    Type    Flags   Addr         Offset       Size          Name
 345         Link    Info    Adralgn      Entsize
 346
 347 [1]     1       2       0x80480d4    0xd4         0x13          .interp
 348         0       0       0x1          0
 349
 350 [2]     5       2       0x80480e8    0xe8         0x388         .hash
 351         3       0       0x4          0x4
 352
 353 [3]     11      2       0x8048470    0x470        0x7f0         .dynsym
 354         4       1       0x4          0x10
 355
 356 [4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
 357         0       0       0x1          0
 358
 359 [5]     9       2       0x8049010    0x1010       0x338         .rel.plt
 360         3       7       0x4          0x8
 361
 362 [6]     1       6       0x8049348    0x1348       0x3           .init
 363         0       0       0x4          0
 364
 365 [7]     1       6       0x804934c    0x134c       0x680         .plt
 366         0       0       0x4          0x4
 367
 368 [8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
 369         0       0       0x4          0
 370
 371 [9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
 372         0       0       0x4          0
 373
 374 [10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
 375         0       0       0x4          0
 376
 377 [11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
 378         0       0       0x4          0
 379
 380 [12]    1       3       0x8088330    0x3f330      0x20afc       .data
 381         0       0       0x4          0
 382
 383 [13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
 384         0       0       0x4          0
 385
 386 [14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
 387         0       0       0x4          0x4
 388
 389 [15]    6       3       0x80a9874    0x60874      0x80          .dynamic
 390         4       0       0x4          0x8
 391
 392 [16]    1       3       0x80a98f4    0x608f4      0x1cf0c       .data
 393         0       0       0x4          0
 394
 395 [17]    8       3       0x80c6800    0x7d800      0             .bss
 396         0       0       0x4          0
 397
 398 [18]    2       0       0            0x7d800      0x9b90        .symtab
 399         19      371     0x4          0x10
 400
 401 [19]    3       0       0            0x87390      0x8526        .strtab
 402         0       0       0x1          0
 403
 404 [20]    3       0       0            0x8f8b6      0x93          .shstrtab
 405         0       0       0x1          0
 406
 407 [21]    1       0       0            0x8f949      0x68b7        .comment
 408         0       0       0x1          0
 409
 410  */
 411 \f
 412 #include <sys/types.h>
 413 #include <stdio.h>
 414 #include <sys/stat.h>
 415 #include <memory.h>
 416 #include <string.h>
 417 #include <errno.h>
 418 #include <unistd.h>
 419 #include <fcntl.h>
 420 #include <elf.h>
 421 #include <sys/mman.h>
 422
 423 #ifndef emacs
 424 #define fatal(a, b, c) fprintf(stderr, a, b, c), exit(1)
 425 #else
 426 extern void fatal(char *, ...);
 427 #endif
 428
 429 /* Get the address of a particular section or program header entry,
 430  * accounting for the size of the entries.
 431  */
 432
 433 #define OLD_SECTION_H(n) \
 434      (*(Elf32_Shdr *) ((byte *) old_section_h + old_file_h->e_shentsize * (n)))
 435 #define NEW_SECTION_H(n) \
 436      (*(Elf32_Shdr *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
 437 #define OLD_PROGRAM_H(n) \
 438      (*(Elf32_Phdr *) ((byte *) old_program_h + old_file_h->e_phentsize * (n)))
 439 #define NEW_PROGRAM_H(n) \
 440      (*(Elf32_Phdr *) ((byte *) new_program_h + new_file_h->e_phentsize * (n)))
 441
 442 #define PATCH_INDEX(n) \
 443   do { \
 444          if ((n) >= old_bss_index) \
 445            (n)++; } while (0)
 446 typedef unsigned char byte;
 447
 448 /* Round X up to a multiple of Y.  */
 449
 450 int
 451 round_up (x, y)
 452      int x, y;
 453 {
 454   int rem = x % y;
 455   if (rem == 0)
 456     return x;
 457   return x - rem + y;
 458 }
 459
 460 /* ****************************************************************
 461  * unexec
 462  *
 463  * driving logic.
 464  *
 465  * In ELF, this works by replacing the old .bss section with a new
 466  * .data section, and inserting an empty .bss immediately afterwards.
 467  *
 468  */
 469 void
 470 unexec (new_name, old_name, data_start, bss_start, entry_address)
 471      char *new_name, *old_name;
 472      unsigned data_start, bss_start, entry_address;
 473 {
 474   extern unsigned int bss_end;
 475   int new_file, old_file, new_file_size;
 476
 477   /* Pointers to the base of the image of the two files. */
 478   caddr_t old_base, new_base;
 479
 480   /* Pointers to the file, program and section headers for the old and new
 481    * files.
 482    */
 483   Elf32_Ehdr *old_file_h, *new_file_h;
 484   Elf32_Phdr *old_program_h, *new_program_h;
 485   Elf32_Shdr *old_section_h, *new_section_h;
 486
 487   /* Point to the section name table in the old file */
 488   char *old_section_names;
 489
 490   Elf32_Addr old_bss_addr, new_bss_addr;
 491   Elf32_Word old_bss_size, new_data2_size;
 492   Elf32_Off  new_data2_offset;
 493   Elf32_Addr new_data2_addr;
 494
 495   int n, nn, old_bss_index, old_data_index, new_data2_index;
 496   struct stat stat_buf;
 497
 498   /* Open the old file & map it into the address space. */
 499
 500   old_file = open (old_name, O_RDONLY);
 501
 502   if (old_file < 0)
 503     fatal ("Can't open %s for reading: errno %d\n", old_name, errno);
 504
 505   if (fstat (old_file, &stat_buf) == -1)
 506     fatal ("Can't fstat(%s): errno %d\n", old_name, errno);
 507
 508   old_base = mmap (0, stat_buf.st_size, PROT_READ, MAP_SHARED, old_file, 0);
 509
 510   if (old_base == (caddr_t) -1)
 511     fatal ("Can't mmap(%s): errno %d\n", old_name, errno);
 512
 513 #ifdef DEBUG
 514   fprintf (stderr, "mmap(%s, %x) -> %x\n", old_name, stat_buf.st_size,
 515            old_base);
 516 #endif
 517
 518   /* Get pointers to headers & section names */
 519
 520   old_file_h = (Elf32_Ehdr *) old_base;
 521   old_program_h = (Elf32_Phdr *) ((byte *) old_base + old_file_h->e_phoff);
 522   old_section_h = (Elf32_Shdr *) ((byte *) old_base + old_file_h->e_shoff);
 523   old_section_names = (char *) old_base
 524     + OLD_SECTION_H(old_file_h->e_shstrndx).sh_offset;
 525
 526   /* Find the old .bss section.  Figure out parameters of the new
 527    * data2 and bss sections.
 528    */
 529
 530   for (old_bss_index = 1; old_bss_index < old_file_h->e_shnum; old_bss_index++)
 531     {
 532 #ifdef DEBUG
 533       fprintf (stderr, "Looking for .bss - found %s\n",
 534                old_section_names + OLD_SECTION_H(old_bss_index).sh_name);
 535 #endif
 536       if (!strcmp (old_section_names + OLD_SECTION_H(old_bss_index).sh_name,
 537                    ".bss"))
 538         break;
 539     }
 540   if (old_bss_index == old_file_h->e_shnum)
 541     fatal ("Can't find .bss in %s.\n", old_name, 0);
 542
 543   old_bss_addr = OLD_SECTION_H(old_bss_index).sh_addr;
 544   old_bss_size = OLD_SECTION_H(old_bss_index).sh_size;
 545 #if defined(emacs) || !defined(DEBUG)
 546   bss_end = (unsigned int) sbrk (0);
 547   new_bss_addr = (Elf32_Addr) bss_end;
 548 #else
 549   new_bss_addr = old_bss_addr + old_bss_size + 0x1234;
 550 #endif
 551   new_data2_addr = old_bss_addr;
 552   new_data2_size = new_bss_addr - old_bss_addr;
 553   new_data2_offset = OLD_SECTION_H(old_bss_index).sh_offset;
 554
 555 #ifdef DEBUG
 556   fprintf (stderr, "old_bss_index %d\n", old_bss_index);
 557   fprintf (stderr, "old_bss_addr %x\n", old_bss_addr);
 558   fprintf (stderr, "old_bss_size %x\n", old_bss_size);
 559   fprintf (stderr, "new_bss_addr %x\n", new_bss_addr);
 560   fprintf (stderr, "new_data2_addr %x\n", new_data2_addr);
 561   fprintf (stderr, "new_data2_size %x\n", new_data2_size);
 562   fprintf (stderr, "new_data2_offset %x\n", new_data2_offset);
 563 #endif
 564
 565   if ((unsigned) new_bss_addr < (unsigned) old_bss_addr + old_bss_size)
 566     fatal (".bss shrank when undumping???\n", 0, 0);
 567
 568   /* Set the output file to the right size and mmap(2) it.  Set
 569    * pointers to various interesting objects.  stat_buf still has
 570    * old_file data.
 571    */
 572
 573   new_file = open (new_name, O_RDWR | O_CREAT, 0666);
 574   if (new_file < 0)
 575     fatal ("Can't creat(%s): errno %d\n", new_name, errno);
 576
 577   new_file_size = stat_buf.st_size + old_file_h->e_shentsize + new_data2_size;
 578
 579   if (ftruncate (new_file, new_file_size))
 580     fatal ("Can't ftruncate(%s): errno %d\n", new_name, errno);
 581
 582   new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_SHARED,
 583                    new_file, 0);
 584
 585   if (new_base == (caddr_t) -1)
 586     fatal ("Can't mmap(%s): errno %d\n", new_name, errno);
 587
 588   new_file_h = (Elf32_Ehdr *) new_base;
 589   new_program_h = (Elf32_Phdr *) ((byte *) new_base + old_file_h->e_phoff);
 590   new_section_h = (Elf32_Shdr *)
 591     ((byte *) new_base + old_file_h->e_shoff + new_data2_size);
 592
 593   /* Make our new file, program and section headers as copies of the
 594    * originals.
 595    */
 596
 597   memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
 598   memcpy (new_program_h, old_program_h,
 599           old_file_h->e_phnum * old_file_h->e_phentsize);
 600
 601   /* Modify the e_shstrndx if necessary. */
 602   PATCH_INDEX (new_file_h->e_shstrndx);
 603
 604   /* Fix up file header.  We'll add one section.  Section header is
 605    * further away now.
 606    */
 607
 608   new_file_h->e_shoff += new_data2_size;
 609   new_file_h->e_shnum += 1;
 610
 611 #ifdef DEBUG
 612   fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff);
 613   fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum);
 614   fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff);
 615   fprintf (stderr, "New section count %d\n", new_file_h->e_shnum);
 616 #endif
 617
 618   /* Fix up a new program header.  Extend the writable data segment so
 619    * that the bss area is covered too. Find that segment by looking
 620    * for a segment that ends just before the .bss area.  Make sure
 621    * that no segments are above the new .data2.  Put a loop at the end
 622    * to adjust the offset and address of any segment that is above
 623    * data2, just in case we decide to allow this later.
 624    */
 625
 626   for (n = new_file_h->e_phnum - 1; n >= 0; n--)
 627     {
 628       /* Compute maximum of all requirements for alignment of section.  */
 629       int alignment = (NEW_PROGRAM_H (n)).p_align;
 630       if ((OLD_SECTION_H (old_bss_index)).sh_addralign > alignment)
 631         alignment = OLD_SECTION_H (old_bss_index).sh_addralign;
 632
 633       if (NEW_PROGRAM_H(n).p_vaddr + NEW_PROGRAM_H(n).p_filesz > old_bss_addr)
 634         fatal ("Program segment above .bss in %s\n", old_name, 0);
 635
 636       if (NEW_PROGRAM_H(n).p_type == PT_LOAD
 637           && (round_up ((NEW_PROGRAM_H (n)).p_vaddr
 638                         + (NEW_PROGRAM_H (n)).p_filesz,
 639                         alignment)
 640               == round_up (old_bss_addr, alignment)))
 641         break;
 642     }
 643   if (n < 0)
 644     fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0);
 645
 646   NEW_PROGRAM_H(n).p_filesz += new_data2_size;
 647   NEW_PROGRAM_H(n).p_memsz = NEW_PROGRAM_H(n).p_filesz;
 648
 649 #if 0 /* Maybe allow section after data2 - does this ever happen? */
 650   for (n = new_file_h->e_phnum - 1; n >= 0; n--)
 651     {
 652       if (NEW_PROGRAM_H(n).p_vaddr
 653           && NEW_PROGRAM_H(n).p_vaddr >= new_data2_addr)
 654         NEW_PROGRAM_H(n).p_vaddr += new_data2_size - old_bss_size;
 655
 656       if (NEW_PROGRAM_H(n).p_offset >= new_data2_offset)
 657         NEW_PROGRAM_H(n).p_offset += new_data2_size;
 658     }
 659 #endif
 660
 661   /* Fix up section headers based on new .data2 section.  Any section
 662    * whose offset or virtual address is after the new .data2 section
 663    * gets its value adjusted.  .bss size becomes zero and new address
 664    * is set.  data2 section header gets added by copying the existing
 665    * .data header and modifying the offset, address and size.
 666    */
 667   for (old_data_index = 1; old_data_index < old_file_h->e_shnum;
 668        old_data_index++)
 669     if (!strcmp (old_section_names + OLD_SECTION_H(old_data_index).sh_name,
 670                  ".data"))
 671       break;
 672   if (old_data_index == old_file_h->e_shnum)
 673     fatal ("Can't find .data in %s.\n", old_name, 0);
 674
 675   /* Walk through all section headers, insert the new data2 section right
 676      before the new bss section. */
 677   for (n = 1, nn = 1; n < old_file_h->e_shnum; n++, nn++)
 678     {
 679       caddr_t src;
 680       /* If it is bss section, insert the new data2 section before it. */
 681       if (n == old_bss_index)
 682         {
 683           /* Steal the data section header for this data2 section. */
 684           memcpy (&NEW_SECTION_H(nn), &OLD_SECTION_H(old_data_index),
 685                   new_file_h->e_shentsize);
 686
 687           NEW_SECTION_H(nn).sh_addr = new_data2_addr;
 688           NEW_SECTION_H(nn).sh_offset = new_data2_offset;
 689           NEW_SECTION_H(nn).sh_size = new_data2_size;
 690           /* Use the bss section's alignment. This will assure that the
 691              new data2 section always be placed in the same spot as the old
 692              bss section by any other application. */
 693           NEW_SECTION_H(nn).sh_addralign = OLD_SECTION_H(n).sh_addralign;
 694
 695           /* Now copy over what we have in the memory now. */
 696           memcpy (NEW_SECTION_H(nn).sh_offset + new_base,
 697                   (caddr_t) OLD_SECTION_H(n).sh_addr,
 698                   new_data2_size);
 699           nn++;
 700         }
 701
 702       memcpy (&NEW_SECTION_H(nn), &OLD_SECTION_H(n),
 703               old_file_h->e_shentsize);
 704
 705       /* The new bss section's size is zero, and its file offset and virtual
 706          address should be off by NEW_DATA2_SIZE. */
 707       if (n == old_bss_index)
 708         {
 709           /* NN should be `old_bss_index + 1' at this point. */
 710           NEW_SECTION_H(nn).sh_offset += new_data2_size;
 711           NEW_SECTION_H(nn).sh_addr += new_data2_size;
 712           /* Let the new bss section address alignment be the same as the
 713              section address alignment followed the old bss section, so
 714              this section will be placed in exactly the same place. */
 715           NEW_SECTION_H(nn).sh_addralign = OLD_SECTION_H(nn).sh_addralign;
 716           NEW_SECTION_H(nn).sh_size = 0;
 717         }
 718       /* Any section that was original placed AFTER the bss section should now
 719          be off by NEW_DATA2_SIZE. */
 720       else if (NEW_SECTION_H(nn).sh_offset >= new_data2_offset)
 721         NEW_SECTION_H(nn).sh_offset += new_data2_size;
 722
 723       /* If any section hdr refers to the section after the new .data
 724          section, make it refer to next one because we have inserted
 725          a new section in between. */
 726
 727       PATCH_INDEX(NEW_SECTION_H(nn).sh_link);
 728       PATCH_INDEX(NEW_SECTION_H(nn).sh_info);
 729
 730       /* Now, start to copy the content of sections. */
 731       if (NEW_SECTION_H(nn).sh_type == SHT_NULL
 732           || NEW_SECTION_H(nn).sh_type == SHT_NOBITS)
 733         continue;
 734
 735       /* Write out the sections. .data and .data1 (and data2, called
 736        * ".data" in the strings table) get copied from the current process
 737        * instead of the old file.
 738        */
 739       if (!strcmp (old_section_names + NEW_SECTION_H(n).sh_name, ".data")
 740           || !strcmp ((old_section_names + NEW_SECTION_H(n).sh_name),
 741                       ".data1"))
 742         src = (caddr_t) OLD_SECTION_H(n).sh_addr;
 743       else
 744         src = old_base + OLD_SECTION_H(n).sh_offset;
 745
 746       memcpy (NEW_SECTION_H(nn).sh_offset + new_base, src,
 747               NEW_SECTION_H(nn).sh_size);
 748
 749       /* If it is the symbol table, its st_shndx field needs to be patched. */
 750       if (NEW_SECTION_H(nn).sh_type == SHT_SYMTAB
 751           || NEW_SECTION_H(nn).sh_type == SHT_DYNSYM)
 752         {
 753           Elf32_Shdr *spt = &NEW_SECTION_H(nn);
 754           unsigned int num = spt->sh_size / spt->sh_entsize;
 755           Elf32_Sym * sym = (Elf32_Sym *) (NEW_SECTION_H(nn).sh_offset +
 756                                            new_base);
 757           for (; num--; sym++)
 758             {
 759               if ((sym->st_shndx == SHN_UNDEF)
 760                   || (sym->st_shndx == SHN_ABS)
 761                   || (sym->st_shndx == SHN_COMMON))
 762                 continue;
 763
 764               PATCH_INDEX(sym->st_shndx);
 765             }
 766         }
 767     }
 768
 769   /* Close the files and make the new file executable */
 770
 771   if (close (old_file))
 772     fatal ("Can't close(%s): errno %d\n", old_name, errno);
 773
 774   if (close (new_file))
 775     fatal ("Can't close(%s): errno %d\n", new_name, errno);
 776
 777   if (stat (new_name, &stat_buf) == -1)
 778     fatal ("Can't stat(%s): errno %d\n", new_name, errno);
 779
 780   n = umask (777);
 781   umask (n);
 782   stat_buf.st_mode |= 0111 & ~n;
 783   if (chmod (new_name, stat_buf.st_mode) == -1)
 784     fatal ("Can't chmod(%s): errno %d\n", new_name, errno);
 785 }