src/unexec.c

   1 /* Copyright (C) 1985, 1986, 1987, 1988, 1992, 1993, 1994, 2001, 2002, 2003,
   2                  2004, 2005, 2006, 2007, 2008, 2009  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 3 of the License, or
   9 (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19
  20 /*
  21  * unexec.c - Convert a running program into an a.out file.
  22  *
  23  * Author:      Spencer W. Thomas
  24  *              Computer Science Dept.
  25  *              University of Utah
  26  * Date:        Tue Mar  2 1982
  27  * Modified heavily since then.
  28  *
  29  * Synopsis:
  30  *      unexec (new_name, a_name, data_start, bss_start, entry_address)
  31  *      char *new_name, *a_name;
  32  *      unsigned data_start, bss_start, entry_address;
  33  *
  34  * Takes a snapshot of the program and makes an a.out format file in the
  35  * file named by the string argument new_name.
  36  * If a_name is non-NULL, the symbol table will be taken from the given file.
  37  * On some machines, an existing a_name file is required.
  38  *
  39  * The boundaries within the a.out file may be adjusted with the data_start
  40  * and bss_start arguments.  Either or both may be given as 0 for defaults.
  41  *
  42  * Data_start gives the boundary between the text segment and the data
  43  * segment of the program.  The text segment can contain shared, read-only
  44  * program code and literal data, while the data segment is always unshared
  45  * and unprotected.  Data_start gives the lowest unprotected address.
  46  * The value you specify may be rounded down to a suitable boundary
  47  * as required by the machine you are using.
  48  *
  49  * Specifying zero for data_start means the boundary between text and data
  50  * should not be the same as when the program was loaded.
  51  * If NO_REMAP is defined, the argument data_start is ignored and the
  52  * segment boundaries are never changed.
  53  *
  54  * Bss_start indicates how much of the data segment is to be saved in the
  55  * a.out file and restored when the program is executed.  It gives the lowest
  56  * unsaved address, and is rounded up to a page boundary.  The default when 0
  57  * is given assumes that the entire data segment is to be stored, including
  58  * the previous data and bss as well as any additional storage allocated with
  59  * break (2).
  60  *
  61  * The new file is set up to start at entry_address.
  62  *
  63  * If you make improvements I'd like to get them too.
  64  * harpo!utah-cs!thomas, thomas@Utah-20
  65  *
  66  */
  67
  68 /* Modified to support SysVr3 shared libraries by James Van Artsdalen
  69  * of Dell Computer Corporation.  james@bigtex.cactus.org.
  70  */
  71
  72 /* There are several compilation parameters affecting unexec:
  73
  74 * COFF
  75
  76 Define this if your system uses COFF for executables.
  77
  78 * NO_REMAP
  79
  80 Define this if you do not want to try to save Emacs's pure data areas
  81 as part of the text segment.
  82
  83 Saving them as text is good because it allows users to share more.
  84
  85 However, on machines that locate the text area far from the data area,
  86 the boundary cannot feasibly be moved.  Such machines require
  87 NO_REMAP.
  88
  89 Also, remapping can cause trouble with the built-in startup routine
  90 /lib/crt0.o, which defines `environ' as an initialized variable.
  91 Dumping `environ' as pure does not work!  So, to use remapping,
  92 you must write a startup routine for your machine in Emacs's crt0.c.
  93 If NO_REMAP is defined, Emacs uses the system's crt0.o.
  94
  95 * SECTION_ALIGNMENT
  96
  97 Some machines that use COFF executables require that each section
  98 start on a certain boundary *in the COFF file*.  Such machines should
  99 define SECTION_ALIGNMENT to a mask of the low-order bits that must be
 100 zero on such a boundary.  This mask is used to control padding between
 101 segments in the COFF file.
 102
 103 If SECTION_ALIGNMENT is not defined, the segments are written
 104 consecutively with no attempt at alignment.  This is right for
 105 unmodified system V.
 106
 107 * SEGMENT_MASK
 108
 109 Some machines require that the beginnings and ends of segments
 110 *in core* be on certain boundaries.  For most machines, a page
 111 boundary is sufficient.  That is the default.  When a larger
 112 boundary is needed, define SEGMENT_MASK to a mask of
 113 the bits that must be zero on such a boundary.
 114
 115 * ADJUST_EXEC_HEADER
 116
 117 This macro can be used to generate statements to adjust or
 118 initialize nonstandard fields in the file header
 119
 120 */
 121
 122 #ifndef emacs
 123 #define PERROR(arg) perror (arg); return -1
 124 #else
 125 #include <config.h>
 126 #define PERROR(file) report_error (file, new)
 127 #endif
 128
 129 #ifndef CANNOT_DUMP  /* all rest of file!  */
 130
 131 #ifdef HAVE_COFF_H
 132 #include <coff.h>
 133 #ifdef MSDOS
 134 #if __DJGPP__ > 1
 135 #include <fcntl.h>  /* for O_RDONLY, O_RDWR */
 136 #include <crt0.h>   /* for _crt0_startup_flags and its bits */
 137 static int save_djgpp_startup_flags;
 138 #endif /* __DJGPP__ > 1 */
 139 #define filehdr external_filehdr
 140 #define scnhdr external_scnhdr
 141 #define syment external_syment
 142 #define auxent external_auxent
 143 #define n_numaux e_numaux
 144 #define n_type e_type
 145 struct aouthdr
 146 {
 147   unsigned short        magic;  /* type of file                         */
 148   unsigned short        vstamp; /* version stamp                        */
 149   unsigned long         tsize;  /* text size in bytes, padded to FW bdry*/
 150   unsigned long         dsize;  /* initialized data "  "                */
 151   unsigned long         bsize;  /* uninitialized data "   "             */
 152   unsigned long         entry;  /* entry pt.                            */
 153   unsigned long         text_start;/* base of text used for this file */
 154   unsigned long         data_start;/* base of data used for this file */
 155 };
 156 #endif /* not MSDOS */
 157 #else  /* not HAVE_COFF_H */
 158 #include <a.out.h>
 159 #endif /* not HAVE_COFF_H */
 160
 161 /* Define getpagesize if the system does not.
 162    Note that this may depend on symbols defined in a.out.h.  */
 163 #include "getpagesize.h"
 164
 165 #ifndef makedev                 /* Try to detect types.h already loaded */
 166 #include <sys/types.h>
 167 #endif /* makedev */
 168 #include <stdio.h>
 169 #include <sys/stat.h>
 170 #include <errno.h>
 171
 172 #include <sys/file.h>
 173
 174 #ifndef O_RDONLY
 175 #define O_RDONLY 0
 176 #endif
 177 #ifndef O_RDWR
 178 #define O_RDWR 2
 179 #endif
 180
 181
 182 extern char *start_of_text ();          /* Start of text */
 183 extern char *start_of_data ();          /* Start of initialized data */
 184
 185 static long block_copy_start;           /* Old executable start point */
 186 static struct filehdr f_hdr;            /* File header */
 187 static struct aouthdr f_ohdr;           /* Optional file header (a.out) */
 188 long bias;                      /* Bias to add for growth */
 189 long lnnoptr;                   /* Pointer to line-number info within file */
 190 #define SYMS_START block_copy_start
 191
 192 static long text_scnptr;
 193 static long data_scnptr;
 194
 195 static long coff_offset;
 196
 197 static int pagemask;
 198
 199 /* Correct an int which is the bit pattern of a pointer to a byte
 200    into an int which is the number of a byte.
 201    This is a no-op on ordinary machines, but not on all.  */
 202
 203 #define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
 204
 205 #ifdef emacs
 206
 207 #include "lisp.h"
 208
 209 static
 210 report_error (file, fd)
 211      char *file;
 212      int fd;
 213 {
 214   if (fd)
 215     close (fd);
 216   report_file_error ("Cannot unexec", Fcons (build_string (file), Qnil));
 217 }
 218 #endif /* emacs */
 219
 220 #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
 221 #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
 222 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
 223
 224 static
 225 report_error_1 (fd, msg, a1, a2)
 226      int fd;
 227      char *msg;
 228      int a1, a2;
 229 {
 230   close (fd);
 231 #ifdef emacs
 232   error (msg, a1, a2);
 233 #else
 234   fprintf (stderr, msg, a1, a2);
 235   fprintf (stderr, "\n");
 236 #endif
 237 }
 238 \f
 239 static int make_hdr ();
 240 static int copy_text_and_data ();
 241 static int copy_sym ();
 242 static void mark_x ();
 243
 244 /* ****************************************************************
 245  * make_hdr
 246  *
 247  * Make the header in the new a.out from the header in core.
 248  * Modify the text and data sizes.
 249  */
 250 static int
 251 make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name)
 252      int new, a_out;
 253      unsigned data_start, bss_start, entry_address;
 254      char *a_name;
 255      char *new_name;
 256 {
 257   int tem;
 258   auto struct scnhdr f_thdr;            /* Text section header */
 259   auto struct scnhdr f_dhdr;            /* Data section header */
 260   auto struct scnhdr f_bhdr;            /* Bss section header */
 261   auto struct scnhdr scntemp;           /* Temporary section header */
 262   register int scns;
 263   unsigned int bss_end;
 264
 265   pagemask = getpagesize () - 1;
 266
 267   /* Adjust text/data boundary. */
 268 #ifdef NO_REMAP
 269   data_start = (int) start_of_data ();
 270 #else /* not NO_REMAP */
 271   if (!data_start)
 272     data_start = (int) start_of_data ();
 273 #endif /* not NO_REMAP */
 274   data_start = ADDR_CORRECT (data_start);
 275
 276 #ifdef SEGMENT_MASK
 277   data_start = data_start & ~SEGMENT_MASK; /* (Down) to segment boundary. */
 278 #else
 279   data_start = data_start & ~pagemask; /* (Down) to page boundary. */
 280 #endif
 281
 282   bss_end = ADDR_CORRECT (sbrk (0)) + pagemask;
 283   bss_end &= ~ pagemask;
 284
 285   /* Adjust data/bss boundary. */
 286   if (bss_start != 0)
 287     {
 288       bss_start = (ADDR_CORRECT (bss_start) + pagemask);
 289       /* (Up) to page bdry. */
 290       bss_start &= ~ pagemask;
 291       if (bss_start > bss_end)
 292         {
 293           ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
 294                   bss_start);
 295         }
 296     }
 297   else
 298     bss_start = bss_end;
 299
 300   if (data_start > bss_start)   /* Can't have negative data size. */
 301     {
 302       ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
 303               data_start, bss_start);
 304     }
 305
 306   coff_offset = 0L;             /* stays zero, except in DJGPP */
 307
 308   /* Salvage as much info from the existing file as possible */
 309   if (a_out >= 0)
 310     {
 311 #ifdef MSDOS
 312 #if __DJGPP__ > 1
 313       /* Support the coff-go32-exe format with a prepended stub, since
 314          this is what GCC 2.8.0 and later generates by default in DJGPP.  */
 315       unsigned short mz_header[3];
 316
 317       if (read (a_out, &mz_header, sizeof (mz_header)) != sizeof (mz_header))
 318         {
 319           PERROR (a_name);
 320         }
 321       if (mz_header[0] == 0x5a4d || mz_header[0] == 0x4d5a) /* "MZ" or "ZM" */
 322         {
 323           coff_offset = (long)mz_header[2] * 512L;
 324           if (mz_header[1])
 325             coff_offset += (long)mz_header[1] - 512L;
 326           lseek (a_out, coff_offset, 0);
 327         }
 328       else
 329         lseek (a_out, 0L, 0);
 330 #endif /* __DJGPP__ > 1 */
 331 #endif /* MSDOS */
 332       if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
 333         {
 334           PERROR (a_name);
 335         }
 336       block_copy_start += sizeof (f_hdr);
 337       if (f_hdr.f_opthdr > 0)
 338         {
 339           if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
 340             {
 341               PERROR (a_name);
 342             }
 343           block_copy_start += sizeof (f_ohdr);
 344         }
 345       /* Loop through section headers, copying them in */
 346       lseek (a_out, coff_offset + sizeof (f_hdr) + f_hdr.f_opthdr, 0);
 347       for (scns = f_hdr.f_nscns; scns > 0; scns--) {
 348         if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
 349           {
 350             PERROR (a_name);
 351           }
 352         if (scntemp.s_scnptr > 0L)
 353           {
 354             if (block_copy_start < scntemp.s_scnptr + scntemp.s_size)
 355               block_copy_start = scntemp.s_scnptr + scntemp.s_size;
 356           }
 357         if (strcmp (scntemp.s_name, ".text") == 0)
 358           {
 359             f_thdr = scntemp;
 360           }
 361         else if (strcmp (scntemp.s_name, ".data") == 0)
 362           {
 363             f_dhdr = scntemp;
 364           }
 365         else if (strcmp (scntemp.s_name, ".bss") == 0)
 366           {
 367             f_bhdr = scntemp;
 368           }
 369       }
 370     }
 371   else
 372     {
 373       ERROR0 ("can't build a COFF file from scratch yet");
 374     }
 375
 376   /* Now we alter the contents of all the f_*hdr variables
 377      to correspond to what we want to dump.  */
 378
 379   f_hdr.f_flags |= (F_RELFLG | F_EXEC);
 380 #ifndef NO_REMAP
 381   f_ohdr.text_start = (long) start_of_text ();
 382   f_ohdr.tsize = data_start - f_ohdr.text_start;
 383   f_ohdr.data_start = data_start;
 384 #endif /* NO_REMAP */
 385   f_ohdr.dsize = bss_start - f_ohdr.data_start;
 386   f_ohdr.bsize = bss_end - bss_start;
 387   /* On some machines, the old values are right.
 388      ??? Maybe on all machines with NO_REMAP.  */
 389   f_thdr.s_size = f_ohdr.tsize;
 390   f_thdr.s_scnptr = sizeof (f_hdr) + sizeof (f_ohdr);
 391   f_thdr.s_scnptr += (f_hdr.f_nscns) * (sizeof (f_thdr));
 392   lnnoptr = f_thdr.s_lnnoptr;
 393 #ifdef SECTION_ALIGNMENT
 394   /* Some systems require special alignment
 395      of the sections in the file itself.  */
 396   f_thdr.s_scnptr
 397     = (f_thdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
 398 #endif /* SECTION_ALIGNMENT */
 399   text_scnptr = f_thdr.s_scnptr;
 400   f_dhdr.s_paddr = f_ohdr.data_start;
 401   f_dhdr.s_vaddr = f_ohdr.data_start;
 402   f_dhdr.s_size = f_ohdr.dsize;
 403   f_dhdr.s_scnptr = f_thdr.s_scnptr + f_thdr.s_size;
 404 #ifdef SECTION_ALIGNMENT
 405   /* Some systems require special alignment
 406      of the sections in the file itself.  */
 407   f_dhdr.s_scnptr
 408     = (f_dhdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
 409 #endif /* SECTION_ALIGNMENT */
 410 #ifdef DATA_SECTION_ALIGNMENT
 411   /* Some systems require special alignment
 412      of the data section only.  */
 413   f_dhdr.s_scnptr
 414     = (f_dhdr.s_scnptr + DATA_SECTION_ALIGNMENT) & ~DATA_SECTION_ALIGNMENT;
 415 #endif /* DATA_SECTION_ALIGNMENT */
 416   data_scnptr = f_dhdr.s_scnptr;
 417   f_bhdr.s_paddr = f_ohdr.data_start + f_ohdr.dsize;
 418   f_bhdr.s_vaddr = f_ohdr.data_start + f_ohdr.dsize;
 419   f_bhdr.s_size = f_ohdr.bsize;
 420   f_bhdr.s_scnptr = 0L;
 421   bias = f_dhdr.s_scnptr + f_dhdr.s_size - block_copy_start;
 422
 423   if (f_hdr.f_symptr > 0L)
 424     {
 425       f_hdr.f_symptr += bias;
 426     }
 427
 428   if (f_thdr.s_lnnoptr > 0L)
 429     {
 430       f_thdr.s_lnnoptr += bias;
 431     }
 432
 433 #ifdef ADJUST_EXEC_HEADER
 434   ADJUST_EXEC_HEADER;
 435 #endif /* ADJUST_EXEC_HEADER */
 436
 437   if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
 438     {
 439       PERROR (new_name);
 440     }
 441
 442   if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
 443     {
 444       PERROR (new_name);
 445     }
 446
 447   if (write (new, &f_thdr, sizeof (f_thdr)) != sizeof (f_thdr))
 448     {
 449       PERROR (new_name);
 450     }
 451
 452   if (write (new, &f_dhdr, sizeof (f_dhdr)) != sizeof (f_dhdr))
 453     {
 454       PERROR (new_name);
 455     }
 456
 457   if (write (new, &f_bhdr, sizeof (f_bhdr)) != sizeof (f_bhdr))
 458     {
 459       PERROR (new_name);
 460     }
 461
 462   return (0);
 463
 464 }
 465 \f
 466 write_segment (new, ptr, end)
 467      int new;
 468      register char *ptr, *end;
 469 {
 470   register int i, nwrite, ret;
 471   char buf[80];
 472 #ifndef USE_CRT_DLL
 473   extern int errno;
 474 #endif
 475   /* This is the normal amount to write at once.
 476      It is the size of block that NFS uses.  */
 477   int writesize = 1 << 13;
 478   int pagesize = getpagesize ();
 479   char zeros[1 << 13];
 480
 481   bzero (zeros, sizeof (zeros));
 482
 483   for (i = 0; ptr < end;)
 484     {
 485       /* Distance to next multiple of writesize.  */
 486       nwrite = (((int) ptr + writesize) & -writesize) - (int) ptr;
 487       /* But not beyond specified end.  */
 488       if (nwrite > end - ptr) nwrite = end - ptr;
 489       ret = write (new, ptr, nwrite);
 490       /* If write gets a page fault, it means we reached
 491          a gap between the old text segment and the old data segment.
 492          This gap has probably been remapped into part of the text segment.
 493          So write zeros for it.  */
 494       if (ret == -1
 495 #ifdef EFAULT
 496           && errno == EFAULT
 497 #endif
 498           )
 499         {
 500           /* Write only a page of zeros at once,
 501              so that we we don't overshoot the start
 502              of the valid memory in the old data segment.  */
 503           if (nwrite > pagesize)
 504             nwrite = pagesize;
 505           write (new, zeros, nwrite);
 506         }
 507 #if 0 /* Now that we have can ask `write' to write more than a page,
 508          it is legit for write do less than the whole amount specified.  */
 509       else if (nwrite != ret)
 510         {
 511           sprintf (buf,
 512                    "unexec write failure: addr 0x%x, fileno %d, size 0x%x, wrote 0x%x, errno %d",
 513                    ptr, new, nwrite, ret, errno);
 514           PERROR (buf);
 515         }
 516 #endif
 517       i += nwrite;
 518       ptr += nwrite;
 519     }
 520 }
 521 /* ****************************************************************
 522  * copy_text_and_data
 523  *
 524  * Copy the text and data segments from memory to the new a.out
 525  */
 526 static int
 527 copy_text_and_data (new, a_out)
 528      int new, a_out;
 529 {
 530   register char *end;
 531   register char *ptr;
 532
 533 #ifdef MSDOS
 534 #if __DJGPP__ >= 2
 535   /* Dump the original table of exception handlers, not the one
 536      where our exception hooks are registered.  */
 537   __djgpp_exception_toggle ();
 538
 539   /* Switch off startup flags that might have been set at runtime
 540      and which might change the way that dumped Emacs works.  */
 541   save_djgpp_startup_flags = _crt0_startup_flags;
 542   _crt0_startup_flags &= ~(_CRT0_FLAG_NO_LFN | _CRT0_FLAG_NEARPTR);
 543 #endif
 544 #endif
 545
 546   lseek (new, (long) text_scnptr, 0);
 547   ptr = (char *) f_ohdr.text_start;
 548   end = ptr + f_ohdr.tsize;
 549   write_segment (new, ptr, end);
 550
 551   lseek (new, (long) data_scnptr, 0);
 552   ptr = (char *) f_ohdr.data_start;
 553   end = ptr + f_ohdr.dsize;
 554   write_segment (new, ptr, end);
 555
 556 #ifdef MSDOS
 557 #if __DJGPP__ >= 2
 558   /* Restore our exception hooks.  */
 559   __djgpp_exception_toggle ();
 560
 561   /* Restore the startup flags.  */
 562   _crt0_startup_flags = save_djgpp_startup_flags;
 563 #endif
 564 #endif
 565
 566
 567   return 0;
 568 }
 569 \f
 570 /* ****************************************************************
 571  * copy_sym
 572  *
 573  * Copy the relocation information and symbol table from the a.out to the new
 574  */
 575 static int
 576 copy_sym (new, a_out, a_name, new_name)
 577      int new, a_out;
 578      char *a_name, *new_name;
 579 {
 580   char page[1024];
 581   int n;
 582
 583   if (a_out < 0)
 584     return 0;
 585
 586   if (SYMS_START == 0L)
 587     return 0;
 588
 589   if (lnnoptr)                  /* if there is line number info */
 590     lseek (a_out, coff_offset + lnnoptr, 0);    /* start copying from there */
 591   else
 592     lseek (a_out, coff_offset + SYMS_START, 0); /* Position a.out to symtab. */
 593
 594   while ((n = read (a_out, page, sizeof page)) > 0)
 595     {
 596       if (write (new, page, n) != n)
 597         {
 598           PERROR (new_name);
 599         }
 600     }
 601   if (n < 0)
 602     {
 603       PERROR (a_name);
 604     }
 605   return 0;
 606 }
 607 \f
 608 /* ****************************************************************
 609  * mark_x
 610  *
 611  * After successfully building the new a.out, mark it executable
 612  */
 613 static void
 614 mark_x (name)
 615      char *name;
 616 {
 617   struct stat sbuf;
 618   int um;
 619   int new = 0;  /* for PERROR */
 620
 621   um = umask (777);
 622   umask (um);
 623   if (stat (name, &sbuf) == -1)
 624     {
 625       PERROR (name);
 626     }
 627   sbuf.st_mode |= 0111 & ~um;
 628   if (chmod (name, sbuf.st_mode) == -1)
 629     PERROR (name);
 630 }
 631 \f
 632 #ifndef COFF_BSD_SYMBOLS
 633
 634 /*
 635  *      If the COFF file contains a symbol table and a line number section,
 636  *      then any auxiliary entries that have values for x_lnnoptr must
 637  *      be adjusted by the amount that the line number section has moved
 638  *      in the file (bias computed in make_hdr).  The #@$%&* designers of
 639  *      the auxiliary entry structures used the absolute file offsets for
 640  *      the line number entry rather than an offset from the start of the
 641  *      line number section!
 642  *
 643  *      When I figure out how to scan through the symbol table and pick out
 644  *      the auxiliary entries that need adjustment, this routine will
 645  *      be fixed.  As it is now, all such entries are wrong and sdb
 646  *      will complain.   Fred Fish, UniSoft Systems Inc.
 647  */
 648
 649 /* This function is probably very slow.  Instead of reopening the new
 650    file for input and output it should copy from the old to the new
 651    using the two descriptors already open (WRITEDESC and READDESC).
 652    Instead of reading one small structure at a time it should use
 653    a reasonable size buffer.  But I don't have time to work on such
 654    things, so I am installing it as submitted to me.  -- RMS.  */
 655
 656 adjust_lnnoptrs (writedesc, readdesc, new_name)
 657      int writedesc;
 658      int readdesc;
 659      char *new_name;
 660 {
 661   register int nsyms;
 662   register int new;
 663   struct syment symentry;
 664   union auxent auxentry;
 665
 666   if (!lnnoptr || !f_hdr.f_symptr)
 667     return 0;
 668
 669 #ifdef MSDOS
 670   if ((new = writedesc) < 0)
 671 #else
 672   if ((new = open (new_name, O_RDWR)) < 0)
 673 #endif
 674     {
 675       PERROR (new_name);
 676       return -1;
 677     }
 678
 679   lseek (new, f_hdr.f_symptr, 0);
 680   for (nsyms = 0; nsyms < f_hdr.f_nsyms; nsyms++)
 681     {
 682       read (new, &symentry, SYMESZ);
 683       if (symentry.n_numaux)
 684         {
 685           read (new, &auxentry, AUXESZ);
 686           nsyms++;
 687           if (ISFCN (symentry.n_type) || symentry.n_type == 0x2400)
 688             {
 689               auxentry.x_sym.x_fcnary.x_fcn.x_lnnoptr += bias;
 690               lseek (new, -AUXESZ, 1);
 691               write (new, &auxentry, AUXESZ);
 692             }
 693         }
 694     }
 695 #ifndef MSDOS
 696   close (new);
 697 #endif
 698   return 0;
 699 }
 700
 701 #endif /* COFF_BSD_SYMBOLS */
 702
 703 /* ****************************************************************
 704  * unexec
 705  *
 706  * driving logic.
 707  */
 708 unexec (new_name, a_name, data_start, bss_start, entry_address)
 709      char *new_name, *a_name;
 710      unsigned data_start, bss_start, entry_address;
 711 {
 712   int new, a_out = -1;
 713
 714   if (a_name && (a_out = open (a_name, O_RDONLY)) < 0)
 715     {
 716       PERROR (a_name);
 717     }
 718   if ((new = creat (new_name, 0666)) < 0)
 719     {
 720       PERROR (new_name);
 721     }
 722
 723   if (make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name) < 0
 724       || copy_text_and_data (new, a_out) < 0
 725       || copy_sym (new, a_out, a_name, new_name) < 0
 726 #ifndef COFF_BSD_SYMBOLS
 727       || adjust_lnnoptrs (new, a_out, new_name) < 0
 728 #endif
 729       )
 730     {
 731       close (new);
 732       /* unlink (new_name);             /* Failed, unlink new a.out */
 733       return -1;
 734     }
 735
 736   close (new);
 737   if (a_out >= 0)
 738     close (a_out);
 739   mark_x (new_name);
 740   return 0;
 741 }
 742
 743 #endif /* not CANNOT_DUMP */
 744
 745 /* arch-tag: 62409b69-e27a-4a7c-9413-0210d6b54e7f
 746    (do not change this comment) */