src/unexec.c

   1 /* Copyright (C) 1985, 1986, 1987, 1988, 1992, 1993, 1994, 2001, 2002, 2003,
   2                  2004, 2005, 2006, 2007, 2008, 2009, 2010  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 <setjmp.h>
 208 #include "lisp.h"
 209
 210 static
 211 report_error (file, fd)
 212      char *file;
 213      int fd;
 214 {
 215   if (fd)
 216     close (fd);
 217   report_file_error ("Cannot unexec", Fcons (build_string (file), Qnil));
 218 }
 219 #endif /* emacs */
 220
 221 #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
 222 #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
 223 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
 224
 225 static
 226 report_error_1 (fd, msg, a1, a2)
 227      int fd;
 228      char *msg;
 229      int a1, a2;
 230 {
 231   close (fd);
 232 #ifdef emacs
 233   error (msg, a1, a2);
 234 #else
 235   fprintf (stderr, msg, a1, a2);
 236   fprintf (stderr, "\n");
 237 #endif
 238 }
 239 \f
 240 static int make_hdr ();
 241 static int copy_text_and_data ();
 242 static int copy_sym ();
 243 static void mark_x ();
 244
 245 /* ****************************************************************
 246  * make_hdr
 247  *
 248  * Make the header in the new a.out from the header in core.
 249  * Modify the text and data sizes.
 250  */
 251 static int
 252 make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name)
 253      int new, a_out;
 254      unsigned data_start, bss_start, entry_address;
 255      char *a_name;
 256      char *new_name;
 257 {
 258   int tem;
 259   auto struct scnhdr f_thdr;            /* Text section header */
 260   auto struct scnhdr f_dhdr;            /* Data section header */
 261   auto struct scnhdr f_bhdr;            /* Bss section header */
 262   auto struct scnhdr scntemp;           /* Temporary section header */
 263   register int scns;
 264   unsigned int bss_end;
 265
 266   pagemask = getpagesize () - 1;
 267
 268   /* Adjust text/data boundary. */
 269 #ifdef NO_REMAP
 270   data_start = (int) start_of_data ();
 271 #else /* not NO_REMAP */
 272   if (!data_start)
 273     data_start = (int) start_of_data ();
 274 #endif /* not NO_REMAP */
 275   data_start = ADDR_CORRECT (data_start);
 276
 277 #ifdef SEGMENT_MASK
 278   data_start = data_start & ~SEGMENT_MASK; /* (Down) to segment boundary. */
 279 #else
 280   data_start = data_start & ~pagemask; /* (Down) to page boundary. */
 281 #endif
 282
 283   bss_end = ADDR_CORRECT (sbrk (0)) + pagemask;
 284   bss_end &= ~ pagemask;
 285
 286   /* Adjust data/bss boundary. */
 287   if (bss_start != 0)
 288     {
 289       bss_start = (ADDR_CORRECT (bss_start) + pagemask);
 290       /* (Up) to page bdry. */
 291       bss_start &= ~ pagemask;
 292       if (bss_start > bss_end)
 293         {
 294           ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
 295                   bss_start);
 296         }
 297     }
 298   else
 299     bss_start = bss_end;
 300
 301   if (data_start > bss_start)   /* Can't have negative data size. */
 302     {
 303       ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
 304               data_start, bss_start);
 305     }
 306
 307   coff_offset = 0L;             /* stays zero, except in DJGPP */
 308
 309   /* Salvage as much info from the existing file as possible */
 310   if (a_out >= 0)
 311     {
 312 #ifdef MSDOS
 313 #if __DJGPP__ > 1
 314       /* Support the coff-go32-exe format with a prepended stub, since
 315          this is what GCC 2.8.0 and later generates by default in DJGPP.  */
 316       unsigned short mz_header[3];
 317
 318       if (read (a_out, &mz_header, sizeof (mz_header)) != sizeof (mz_header))
 319         {
 320           PERROR (a_name);
 321         }
 322       if (mz_header[0] == 0x5a4d || mz_header[0] == 0x4d5a) /* "MZ" or "ZM" */
 323         {
 324           coff_offset = (long)mz_header[2] * 512L;
 325           if (mz_header[1])
 326             coff_offset += (long)mz_header[1] - 512L;
 327           lseek (a_out, coff_offset, 0);
 328         }
 329       else
 330         lseek (a_out, 0L, 0);
 331 #endif /* __DJGPP__ > 1 */
 332 #endif /* MSDOS */
 333       if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
 334         {
 335           PERROR (a_name);
 336         }
 337       block_copy_start += sizeof (f_hdr);
 338       if (f_hdr.f_opthdr > 0)
 339         {
 340           if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
 341             {
 342               PERROR (a_name);
 343             }
 344           block_copy_start += sizeof (f_ohdr);
 345         }
 346       /* Loop through section headers, copying them in */
 347       lseek (a_out, coff_offset + sizeof (f_hdr) + f_hdr.f_opthdr, 0);
 348       for (scns = f_hdr.f_nscns; scns > 0; scns--) {
 349         if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
 350           {
 351             PERROR (a_name);
 352           }
 353         if (scntemp.s_scnptr > 0L)
 354           {
 355             if (block_copy_start < scntemp.s_scnptr + scntemp.s_size)
 356               block_copy_start = scntemp.s_scnptr + scntemp.s_size;
 357           }
 358         if (strcmp (scntemp.s_name, ".text") == 0)
 359           {
 360             f_thdr = scntemp;
 361           }
 362         else if (strcmp (scntemp.s_name, ".data") == 0)
 363           {
 364             f_dhdr = scntemp;
 365           }
 366         else if (strcmp (scntemp.s_name, ".bss") == 0)
 367           {
 368             f_bhdr = scntemp;
 369           }
 370       }
 371     }
 372   else
 373     {
 374       ERROR0 ("can't build a COFF file from scratch yet");
 375     }
 376
 377   /* Now we alter the contents of all the f_*hdr variables
 378      to correspond to what we want to dump.  */
 379
 380   f_hdr.f_flags |= (F_RELFLG | F_EXEC);
 381 #ifndef NO_REMAP
 382   f_ohdr.text_start = (long) start_of_text ();
 383   f_ohdr.tsize = data_start - f_ohdr.text_start;
 384   f_ohdr.data_start = data_start;
 385 #endif /* NO_REMAP */
 386   f_ohdr.dsize = bss_start - f_ohdr.data_start;
 387   f_ohdr.bsize = bss_end - bss_start;
 388   /* On some machines, the old values are right.
 389      ??? Maybe on all machines with NO_REMAP.  */
 390   f_thdr.s_size = f_ohdr.tsize;
 391   f_thdr.s_scnptr = sizeof (f_hdr) + sizeof (f_ohdr);
 392   f_thdr.s_scnptr += (f_hdr.f_nscns) * (sizeof (f_thdr));
 393   lnnoptr = f_thdr.s_lnnoptr;
 394 #ifdef SECTION_ALIGNMENT
 395   /* Some systems require special alignment
 396      of the sections in the file itself.  */
 397   f_thdr.s_scnptr
 398     = (f_thdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
 399 #endif /* SECTION_ALIGNMENT */
 400   text_scnptr = f_thdr.s_scnptr;
 401   f_dhdr.s_paddr = f_ohdr.data_start;
 402   f_dhdr.s_vaddr = f_ohdr.data_start;
 403   f_dhdr.s_size = f_ohdr.dsize;
 404   f_dhdr.s_scnptr = f_thdr.s_scnptr + f_thdr.s_size;
 405 #ifdef SECTION_ALIGNMENT
 406   /* Some systems require special alignment
 407      of the sections in the file itself.  */
 408   f_dhdr.s_scnptr
 409     = (f_dhdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
 410 #endif /* SECTION_ALIGNMENT */
 411 #ifdef DATA_SECTION_ALIGNMENT
 412   /* Some systems require special alignment
 413      of the data section only.  */
 414   f_dhdr.s_scnptr
 415     = (f_dhdr.s_scnptr + DATA_SECTION_ALIGNMENT) & ~DATA_SECTION_ALIGNMENT;
 416 #endif /* DATA_SECTION_ALIGNMENT */
 417   data_scnptr = f_dhdr.s_scnptr;
 418   f_bhdr.s_paddr = f_ohdr.data_start + f_ohdr.dsize;
 419   f_bhdr.s_vaddr = f_ohdr.data_start + f_ohdr.dsize;
 420   f_bhdr.s_size = f_ohdr.bsize;
 421   f_bhdr.s_scnptr = 0L;
 422   bias = f_dhdr.s_scnptr + f_dhdr.s_size - block_copy_start;
 423
 424   if (f_hdr.f_symptr > 0L)
 425     {
 426       f_hdr.f_symptr += bias;
 427     }
 428
 429   if (f_thdr.s_lnnoptr > 0L)
 430     {
 431       f_thdr.s_lnnoptr += bias;
 432     }
 433
 434 #ifdef ADJUST_EXEC_HEADER
 435   ADJUST_EXEC_HEADER;
 436 #endif /* ADJUST_EXEC_HEADER */
 437
 438   if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
 439     {
 440       PERROR (new_name);
 441     }
 442
 443   if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
 444     {
 445       PERROR (new_name);
 446     }
 447
 448   if (write (new, &f_thdr, sizeof (f_thdr)) != sizeof (f_thdr))
 449     {
 450       PERROR (new_name);
 451     }
 452
 453   if (write (new, &f_dhdr, sizeof (f_dhdr)) != sizeof (f_dhdr))
 454     {
 455       PERROR (new_name);
 456     }
 457
 458   if (write (new, &f_bhdr, sizeof (f_bhdr)) != sizeof (f_bhdr))
 459     {
 460       PERROR (new_name);
 461     }
 462
 463   return (0);
 464
 465 }
 466 \f
 467 write_segment (new, ptr, end)
 468      int new;
 469      register char *ptr, *end;
 470 {
 471   register int i, nwrite, ret;
 472   char buf[80];
 473 #ifndef USE_CRT_DLL
 474   extern int errno;
 475 #endif
 476   /* This is the normal amount to write at once.
 477      It is the size of block that NFS uses.  */
 478   int writesize = 1 << 13;
 479   int pagesize = getpagesize ();
 480   char zeros[1 << 13];
 481
 482   bzero (zeros, sizeof (zeros));
 483
 484   for (i = 0; ptr < end;)
 485     {
 486       /* Distance to next multiple of writesize.  */
 487       nwrite = (((int) ptr + writesize) & -writesize) - (int) ptr;
 488       /* But not beyond specified end.  */
 489       if (nwrite > end - ptr) nwrite = end - ptr;
 490       ret = write (new, ptr, nwrite);
 491       /* If write gets a page fault, it means we reached
 492          a gap between the old text segment and the old data segment.
 493          This gap has probably been remapped into part of the text segment.
 494          So write zeros for it.  */
 495       if (ret == -1
 496 #ifdef EFAULT
 497           && errno == EFAULT
 498 #endif
 499           )
 500         {
 501           /* Write only a page of zeros at once,
 502              so that we don't overshoot the start
 503              of the valid memory in the old data segment.  */
 504           if (nwrite > pagesize)
 505             nwrite = pagesize;
 506           write (new, zeros, nwrite);
 507         }
 508 #if 0 /* Now that we have can ask `write' to write more than a page,
 509          it is legit for write do less than the whole amount specified.  */
 510       else if (nwrite != ret)
 511         {
 512           sprintf (buf,
 513                    "unexec write failure: addr 0x%x, fileno %d, size 0x%x, wrote 0x%x, errno %d",
 514                    ptr, new, nwrite, ret, errno);
 515           PERROR (buf);
 516         }
 517 #endif
 518       i += nwrite;
 519       ptr += nwrite;
 520     }
 521 }
 522 /* ****************************************************************
 523  * copy_text_and_data
 524  *
 525  * Copy the text and data segments from memory to the new a.out
 526  */
 527 static int
 528 copy_text_and_data (new, a_out)
 529      int new, a_out;
 530 {
 531   register char *end;
 532   register char *ptr;
 533
 534 #ifdef MSDOS
 535 #if __DJGPP__ >= 2
 536   /* Dump the original table of exception handlers, not the one
 537      where our exception hooks are registered.  */
 538   __djgpp_exception_toggle ();
 539
 540   /* Switch off startup flags that might have been set at runtime
 541      and which might change the way that dumped Emacs works.  */
 542   save_djgpp_startup_flags = _crt0_startup_flags;
 543   _crt0_startup_flags &= ~(_CRT0_FLAG_NO_LFN | _CRT0_FLAG_NEARPTR);
 544 #endif
 545 #endif
 546
 547   lseek (new, (long) text_scnptr, 0);
 548   ptr = (char *) f_ohdr.text_start;
 549   end = ptr + f_ohdr.tsize;
 550   write_segment (new, ptr, end);
 551
 552   lseek (new, (long) data_scnptr, 0);
 553   ptr = (char *) f_ohdr.data_start;
 554   end = ptr + f_ohdr.dsize;
 555   write_segment (new, ptr, end);
 556
 557 #ifdef MSDOS
 558 #if __DJGPP__ >= 2
 559   /* Restore our exception hooks.  */
 560   __djgpp_exception_toggle ();
 561
 562   /* Restore the startup flags.  */
 563   _crt0_startup_flags = save_djgpp_startup_flags;
 564 #endif
 565 #endif
 566
 567
 568   return 0;
 569 }
 570 \f
 571 /* ****************************************************************
 572  * copy_sym
 573  *
 574  * Copy the relocation information and symbol table from the a.out to the new
 575  */
 576 static int
 577 copy_sym (new, a_out, a_name, new_name)
 578      int new, a_out;
 579      char *a_name, *new_name;
 580 {
 581   char page[1024];
 582   int n;
 583
 584   if (a_out < 0)
 585     return 0;
 586
 587   if (SYMS_START == 0L)
 588     return 0;
 589
 590   if (lnnoptr)                  /* if there is line number info */
 591     lseek (a_out, coff_offset + lnnoptr, 0);    /* start copying from there */
 592   else
 593     lseek (a_out, coff_offset + SYMS_START, 0); /* Position a.out to symtab. */
 594
 595   while ((n = read (a_out, page, sizeof page)) > 0)
 596     {
 597       if (write (new, page, n) != n)
 598         {
 599           PERROR (new_name);
 600         }
 601     }
 602   if (n < 0)
 603     {
 604       PERROR (a_name);
 605     }
 606   return 0;
 607 }
 608 \f
 609 /* ****************************************************************
 610  * mark_x
 611  *
 612  * After successfully building the new a.out, mark it executable
 613  */
 614 static void
 615 mark_x (name)
 616      char *name;
 617 {
 618   struct stat sbuf;
 619   int um;
 620   int new = 0;  /* for PERROR */
 621
 622   um = umask (777);
 623   umask (um);
 624   if (stat (name, &sbuf) == -1)
 625     {
 626       PERROR (name);
 627     }
 628   sbuf.st_mode |= 0111 & ~um;
 629   if (chmod (name, sbuf.st_mode) == -1)
 630     PERROR (name);
 631 }
 632 \f
 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 /* ****************************************************************
 702  * unexec
 703  *
 704  * driving logic.
 705  */
 706 unexec (new_name, a_name, data_start, bss_start, entry_address)
 707      char *new_name, *a_name;
 708      unsigned data_start, bss_start, entry_address;
 709 {
 710   int new, a_out = -1;
 711
 712   if (a_name && (a_out = open (a_name, O_RDONLY)) < 0)
 713     {
 714       PERROR (a_name);
 715     }
 716   if ((new = creat (new_name, 0666)) < 0)
 717     {
 718       PERROR (new_name);
 719     }
 720
 721   if (make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name) < 0
 722       || copy_text_and_data (new, a_out) < 0
 723       || copy_sym (new, a_out, a_name, new_name) < 0
 724       || adjust_lnnoptrs (new, a_out, new_name) < 0
 725       )
 726     {
 727       close (new);
 728       /* unlink (new_name);             /* Failed, unlink new a.out */
 729       return -1;
 730     }
 731
 732   close (new);
 733   if (a_out >= 0)
 734     close (a_out);
 735   mark_x (new_name);
 736   return 0;
 737 }
 738
 739 #endif /* not CANNOT_DUMP */
 740
 741 /* arch-tag: 62409b69-e27a-4a7c-9413-0210d6b54e7f
 742    (do not change this comment) */