src/unexec.c

   1 /* Copyright (C) 1985, 1986, 1987, 1988, 1992, 1993, 1994, 2001, 2002, 2003,
   2                  2004, 2005, 2006, 2007, 2008  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 * A_TEXT_OFFSET(HDR)
 116
 117 Some machines count the a.out header as part of the size of the text
 118 segment (a_text); they may actually load the header into core as the
 119 first data in the text segment.  Some have additional padding between
 120 the header and the real text of the program that is counted in a_text.
 121
 122 For these machines, define A_TEXT_OFFSET(HDR) to examine the header
 123 structure HDR and return the number of bytes to add to `a_text'
 124 before writing it (above and beyond the number of bytes of actual
 125 program text).  HDR's standard fields are already correct, except that
 126 this adjustment to the `a_text' field has not yet been made;
 127 thus, the amount of offset can depend on the data in the file.
 128
 129 * A_TEXT_SEEK(HDR)
 130
 131 If defined, this macro specifies the number of bytes to seek into the
 132 a.out file before starting to write the text segment.
 133
 134 * ADJUST_EXEC_HEADER
 135
 136 This macro can be used to generate statements to adjust or
 137 initialize nonstandard fields in the file header
 138
 139 * ADDR_CORRECT(ADDR)
 140
 141 Macro to correct an int which is the bit pattern of a pointer to a byte
 142 into an int which is the number of a byte.
 143
 144 This macro has a default definition which is usually right.
 145 This default definition is a no-op on most machines (where a
 146 pointer looks like an int) but not on all machines.
 147
 148 */
 149
 150 #ifndef emacs
 151 #define PERROR(arg) perror (arg); return -1
 152 #else
 153 #include <config.h>
 154 #define PERROR(file) report_error (file, new)
 155 #endif
 156
 157 #ifndef CANNOT_DUMP  /* all rest of file!  */
 158
 159 #if defined(COFF) && defined(HAVE_COFF_H)
 160 #include <coff.h>
 161 #ifdef MSDOS
 162 #if __DJGPP__ > 1
 163 #include <fcntl.h>  /* for O_RDONLY, O_RDWR */
 164 #include <crt0.h>   /* for _crt0_startup_flags and its bits */
 165 static int save_djgpp_startup_flags;
 166 #endif /* __DJGPP__ > 1 */
 167 #define filehdr external_filehdr
 168 #define scnhdr external_scnhdr
 169 #define syment external_syment
 170 #define auxent external_auxent
 171 #define n_numaux e_numaux
 172 #define n_type e_type
 173 struct aouthdr
 174 {
 175   unsigned short        magic;  /* type of file                         */
 176   unsigned short        vstamp; /* version stamp                        */
 177   unsigned long         tsize;  /* text size in bytes, padded to FW bdry*/
 178   unsigned long         dsize;  /* initialized data "  "                */
 179   unsigned long         bsize;  /* uninitialized data "   "             */
 180   unsigned long         entry;  /* entry pt.                            */
 181   unsigned long         text_start;/* base of text used for this file */
 182   unsigned long         data_start;/* base of data used for this file */
 183 };
 184 #endif /* not MSDOS */
 185 #else  /* not COFF */
 186 #include <a.out.h>
 187 #endif /* not COFF */
 188
 189 /* Define getpagesize if the system does not.
 190    Note that this may depend on symbols defined in a.out.h.  */
 191 #include "getpagesize.h"
 192
 193 #ifndef makedev                 /* Try to detect types.h already loaded */
 194 #include <sys/types.h>
 195 #endif /* makedev */
 196 #include <stdio.h>
 197 #include <sys/stat.h>
 198 #include <errno.h>
 199
 200 #include <sys/file.h>   /* Must be after sys/types.h for USG*/
 201
 202 #ifdef USG5
 203 #include <fcntl.h>
 204 #endif
 205
 206 #ifndef O_RDONLY
 207 #define O_RDONLY 0
 208 #endif
 209 #ifndef O_RDWR
 210 #define O_RDWR 2
 211 #endif
 212
 213
 214 extern char *start_of_text ();          /* Start of text */
 215 extern char *start_of_data ();          /* Start of initialized data */
 216
 217 #ifdef COFF
 218 static long block_copy_start;           /* Old executable start point */
 219 static struct filehdr f_hdr;            /* File header */
 220 static struct aouthdr f_ohdr;           /* Optional file header (a.out) */
 221 long bias;                      /* Bias to add for growth */
 222 long lnnoptr;                   /* Pointer to line-number info within file */
 223 #define SYMS_START block_copy_start
 224
 225 static long text_scnptr;
 226 static long data_scnptr;
 227
 228 static long coff_offset;
 229
 230 #else /* not COFF */
 231
 232 extern char *sbrk ();
 233
 234 #define SYMS_START ((long) N_SYMOFF (ohdr))
 235
 236 #if defined (USG)
 237 static struct bhdr hdr, ohdr;
 238 #define a_magic fmagic
 239 #define a_text tsize
 240 #define a_data dsize
 241 #define a_bss bsize
 242 #define a_syms ssize
 243 #define a_trsize rtsize
 244 #define a_drsize rdsize
 245 #define a_entry entry
 246 #define N_BADMAG(x) \
 247     (((x).fmagic)!=OMAGIC && ((x).fmagic)!=NMAGIC &&\
 248      ((x).fmagic)!=FMAGIC && ((x).fmagic)!=IMAGIC)
 249 #define NEWMAGIC FMAGIC
 250 #else /* not USG */
 251 static struct exec hdr, ohdr;
 252 #define NEWMAGIC ZMAGIC
 253 #endif /* not USG */
 254
 255 static int unexec_text_start;
 256 static int unexec_data_start;
 257
 258 #endif /* not COFF */
 259
 260 static int pagemask;
 261
 262 /* Correct an int which is the bit pattern of a pointer to a byte
 263    into an int which is the number of a byte.
 264    This is a no-op on ordinary machines, but not on all.  */
 265
 266 #ifndef ADDR_CORRECT   /* Let m-*.h files override this definition */
 267 #define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
 268 #endif
 269
 270 #ifdef emacs
 271
 272 #include "lisp.h"
 273
 274 static
 275 report_error (file, fd)
 276      char *file;
 277      int fd;
 278 {
 279   if (fd)
 280     close (fd);
 281   report_file_error ("Cannot unexec", Fcons (build_string (file), Qnil));
 282 }
 283 #endif /* emacs */
 284
 285 #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
 286 #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
 287 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
 288
 289 static
 290 report_error_1 (fd, msg, a1, a2)
 291      int fd;
 292      char *msg;
 293      int a1, a2;
 294 {
 295   close (fd);
 296 #ifdef emacs
 297   error (msg, a1, a2);
 298 #else
 299   fprintf (stderr, msg, a1, a2);
 300   fprintf (stderr, "\n");
 301 #endif
 302 }
 303 \f
 304 static int make_hdr ();
 305 static int copy_text_and_data ();
 306 static int copy_sym ();
 307 static void mark_x ();
 308
 309 /* ****************************************************************
 310  * make_hdr
 311  *
 312  * Make the header in the new a.out from the header in core.
 313  * Modify the text and data sizes.
 314  */
 315 static int
 316 make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name)
 317      int new, a_out;
 318      unsigned data_start, bss_start, entry_address;
 319      char *a_name;
 320      char *new_name;
 321 {
 322   int tem;
 323 #ifdef COFF
 324   auto struct scnhdr f_thdr;            /* Text section header */
 325   auto struct scnhdr f_dhdr;            /* Data section header */
 326   auto struct scnhdr f_bhdr;            /* Bss section header */
 327   auto struct scnhdr scntemp;           /* Temporary section header */
 328   register int scns;
 329 #endif /* COFF */
 330   unsigned int bss_end;
 331
 332   pagemask = getpagesize () - 1;
 333
 334   /* Adjust text/data boundary. */
 335 #ifdef NO_REMAP
 336   data_start = (int) start_of_data ();
 337 #else /* not NO_REMAP */
 338   if (!data_start)
 339     data_start = (int) start_of_data ();
 340 #endif /* not NO_REMAP */
 341   data_start = ADDR_CORRECT (data_start);
 342
 343 #ifdef SEGMENT_MASK
 344   data_start = data_start & ~SEGMENT_MASK; /* (Down) to segment boundary. */
 345 #else
 346   data_start = data_start & ~pagemask; /* (Down) to page boundary. */
 347 #endif
 348
 349   bss_end = ADDR_CORRECT (sbrk (0)) + pagemask;
 350   bss_end &= ~ pagemask;
 351
 352   /* Adjust data/bss boundary. */
 353   if (bss_start != 0)
 354     {
 355       bss_start = (ADDR_CORRECT (bss_start) + pagemask);
 356       /* (Up) to page bdry. */
 357       bss_start &= ~ pagemask;
 358       if (bss_start > bss_end)
 359         {
 360           ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
 361                   bss_start);
 362         }
 363     }
 364   else
 365     bss_start = bss_end;
 366
 367   if (data_start > bss_start)   /* Can't have negative data size. */
 368     {
 369       ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
 370               data_start, bss_start);
 371     }
 372
 373 #ifdef COFF
 374   coff_offset = 0L;             /* stays zero, except in DJGPP */
 375
 376   /* Salvage as much info from the existing file as possible */
 377   if (a_out >= 0)
 378     {
 379 #ifdef MSDOS
 380 #if __DJGPP__ > 1
 381       /* Support the coff-go32-exe format with a prepended stub, since
 382          this is what GCC 2.8.0 and later generates by default in DJGPP.  */
 383       unsigned short mz_header[3];
 384
 385       if (read (a_out, &mz_header, sizeof (mz_header)) != sizeof (mz_header))
 386         {
 387           PERROR (a_name);
 388         }
 389       if (mz_header[0] == 0x5a4d || mz_header[0] == 0x4d5a) /* "MZ" or "ZM" */
 390         {
 391           coff_offset = (long)mz_header[2] * 512L;
 392           if (mz_header[1])
 393             coff_offset += (long)mz_header[1] - 512L;
 394           lseek (a_out, coff_offset, 0);
 395         }
 396       else
 397         lseek (a_out, 0L, 0);
 398 #endif /* __DJGPP__ > 1 */
 399 #endif /* MSDOS */
 400       if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
 401         {
 402           PERROR (a_name);
 403         }
 404       block_copy_start += sizeof (f_hdr);
 405       if (f_hdr.f_opthdr > 0)
 406         {
 407           if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
 408             {
 409               PERROR (a_name);
 410             }
 411           block_copy_start += sizeof (f_ohdr);
 412         }
 413       /* Loop through section headers, copying them in */
 414       lseek (a_out, coff_offset + sizeof (f_hdr) + f_hdr.f_opthdr, 0);
 415       for (scns = f_hdr.f_nscns; scns > 0; scns--) {
 416         if (read (a_out, &scntemp, sizeof (scntemp)) != sizeof (scntemp))
 417           {
 418             PERROR (a_name);
 419           }
 420         if (scntemp.s_scnptr > 0L)
 421           {
 422             if (block_copy_start < scntemp.s_scnptr + scntemp.s_size)
 423               block_copy_start = scntemp.s_scnptr + scntemp.s_size;
 424           }
 425         if (strcmp (scntemp.s_name, ".text") == 0)
 426           {
 427             f_thdr = scntemp;
 428           }
 429         else if (strcmp (scntemp.s_name, ".data") == 0)
 430           {
 431             f_dhdr = scntemp;
 432           }
 433         else if (strcmp (scntemp.s_name, ".bss") == 0)
 434           {
 435             f_bhdr = scntemp;
 436           }
 437       }
 438     }
 439   else
 440     {
 441       ERROR0 ("can't build a COFF file from scratch yet");
 442     }
 443
 444   /* Now we alter the contents of all the f_*hdr variables
 445      to correspond to what we want to dump.  */
 446
 447   f_hdr.f_flags |= (F_RELFLG | F_EXEC);
 448 #ifndef NO_REMAP
 449   f_ohdr.text_start = (long) start_of_text ();
 450   f_ohdr.tsize = data_start - f_ohdr.text_start;
 451   f_ohdr.data_start = data_start;
 452 #endif /* NO_REMAP */
 453   f_ohdr.dsize = bss_start - f_ohdr.data_start;
 454   f_ohdr.bsize = bss_end - bss_start;
 455   /* On some machines, the old values are right.
 456      ??? Maybe on all machines with NO_REMAP.  */
 457   f_thdr.s_size = f_ohdr.tsize;
 458   f_thdr.s_scnptr = sizeof (f_hdr) + sizeof (f_ohdr);
 459   f_thdr.s_scnptr += (f_hdr.f_nscns) * (sizeof (f_thdr));
 460   lnnoptr = f_thdr.s_lnnoptr;
 461 #ifdef SECTION_ALIGNMENT
 462   /* Some systems require special alignment
 463      of the sections in the file itself.  */
 464   f_thdr.s_scnptr
 465     = (f_thdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
 466 #endif /* SECTION_ALIGNMENT */
 467   text_scnptr = f_thdr.s_scnptr;
 468   f_dhdr.s_paddr = f_ohdr.data_start;
 469   f_dhdr.s_vaddr = f_ohdr.data_start;
 470   f_dhdr.s_size = f_ohdr.dsize;
 471   f_dhdr.s_scnptr = f_thdr.s_scnptr + f_thdr.s_size;
 472 #ifdef SECTION_ALIGNMENT
 473   /* Some systems require special alignment
 474      of the sections in the file itself.  */
 475   f_dhdr.s_scnptr
 476     = (f_dhdr.s_scnptr + SECTION_ALIGNMENT) & ~SECTION_ALIGNMENT;
 477 #endif /* SECTION_ALIGNMENT */
 478 #ifdef DATA_SECTION_ALIGNMENT
 479   /* Some systems require special alignment
 480      of the data section only.  */
 481   f_dhdr.s_scnptr
 482     = (f_dhdr.s_scnptr + DATA_SECTION_ALIGNMENT) & ~DATA_SECTION_ALIGNMENT;
 483 #endif /* DATA_SECTION_ALIGNMENT */
 484   data_scnptr = f_dhdr.s_scnptr;
 485   f_bhdr.s_paddr = f_ohdr.data_start + f_ohdr.dsize;
 486   f_bhdr.s_vaddr = f_ohdr.data_start + f_ohdr.dsize;
 487   f_bhdr.s_size = f_ohdr.bsize;
 488   f_bhdr.s_scnptr = 0L;
 489   bias = f_dhdr.s_scnptr + f_dhdr.s_size - block_copy_start;
 490
 491   if (f_hdr.f_symptr > 0L)
 492     {
 493       f_hdr.f_symptr += bias;
 494     }
 495
 496   if (f_thdr.s_lnnoptr > 0L)
 497     {
 498       f_thdr.s_lnnoptr += bias;
 499     }
 500
 501 #ifdef ADJUST_EXEC_HEADER
 502   ADJUST_EXEC_HEADER;
 503 #endif /* ADJUST_EXEC_HEADER */
 504
 505   if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
 506     {
 507       PERROR (new_name);
 508     }
 509
 510   if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
 511     {
 512       PERROR (new_name);
 513     }
 514
 515   if (write (new, &f_thdr, sizeof (f_thdr)) != sizeof (f_thdr))
 516     {
 517       PERROR (new_name);
 518     }
 519
 520   if (write (new, &f_dhdr, sizeof (f_dhdr)) != sizeof (f_dhdr))
 521     {
 522       PERROR (new_name);
 523     }
 524
 525   if (write (new, &f_bhdr, sizeof (f_bhdr)) != sizeof (f_bhdr))
 526     {
 527       PERROR (new_name);
 528     }
 529
 530   return (0);
 531
 532 #else /* if not COFF */
 533
 534   /* Get symbol table info from header of a.out file if given one. */
 535   if (a_out >= 0)
 536     {
 537       if (read (a_out, &ohdr, sizeof hdr) != sizeof hdr)
 538         {
 539           PERROR (a_name);
 540         }
 541
 542       if (N_BADMAG (ohdr))
 543         {
 544           ERROR1 ("invalid magic number in %s", a_name);
 545         }
 546       hdr = ohdr;
 547     }
 548   else
 549     {
 550 #ifdef MSDOS    /* Demacs 1.1.1 91/10/16 HIRANO Satoshi */
 551       bzero ((void *)&hdr, sizeof hdr);
 552 #else
 553       bzero (&hdr, sizeof hdr);
 554 #endif
 555     }
 556
 557   unexec_text_start = (long) start_of_text ();
 558   unexec_data_start = data_start;
 559
 560   /* Machine-dependent fixup for header, or maybe for unexec_text_start */
 561 #ifdef ADJUST_EXEC_HEADER
 562   ADJUST_EXEC_HEADER;
 563 #endif /* ADJUST_EXEC_HEADER */
 564
 565   hdr.a_trsize = 0;
 566   hdr.a_drsize = 0;
 567   if (entry_address != 0)
 568     hdr.a_entry = entry_address;
 569
 570   hdr.a_bss = bss_end - bss_start;
 571   hdr.a_data = bss_start - data_start;
 572 #ifdef NO_REMAP
 573   hdr.a_text = ohdr.a_text;
 574 #else /* not NO_REMAP */
 575   hdr.a_text = data_start - unexec_text_start;
 576
 577 #ifdef A_TEXT_OFFSET
 578   hdr.a_text += A_TEXT_OFFSET (ohdr);
 579 #endif
 580
 581 #endif /* not NO_REMAP */
 582
 583   if (write (new, &hdr, sizeof hdr) != sizeof hdr)
 584     {
 585       PERROR (new_name);
 586     }
 587
 588 #ifdef A_TEXT_OFFSET
 589   hdr.a_text -= A_TEXT_OFFSET (ohdr);
 590 #endif
 591
 592   return 0;
 593
 594 #endif /* not COFF */
 595 }
 596 \f
 597 write_segment (new, ptr, end)
 598      int new;
 599      register char *ptr, *end;
 600 {
 601   register int i, nwrite, ret;
 602   char buf[80];
 603 #ifndef USE_CRT_DLL
 604   extern int errno;
 605 #endif
 606   /* This is the normal amount to write at once.
 607      It is the size of block that NFS uses.  */
 608   int writesize = 1 << 13;
 609   int pagesize = getpagesize ();
 610   char zeros[1 << 13];
 611
 612   bzero (zeros, sizeof (zeros));
 613
 614   for (i = 0; ptr < end;)
 615     {
 616       /* Distance to next multiple of writesize.  */
 617       nwrite = (((int) ptr + writesize) & -writesize) - (int) ptr;
 618       /* But not beyond specified end.  */
 619       if (nwrite > end - ptr) nwrite = end - ptr;
 620       ret = write (new, ptr, nwrite);
 621       /* If write gets a page fault, it means we reached
 622          a gap between the old text segment and the old data segment.
 623          This gap has probably been remapped into part of the text segment.
 624          So write zeros for it.  */
 625       if (ret == -1
 626 #ifdef EFAULT
 627           && errno == EFAULT
 628 #endif
 629           )
 630         {
 631           /* Write only a page of zeros at once,
 632              so that we we don't overshoot the start
 633              of the valid memory in the old data segment.  */
 634           if (nwrite > pagesize)
 635             nwrite = pagesize;
 636           write (new, zeros, nwrite);
 637         }
 638 #if 0 /* Now that we have can ask `write' to write more than a page,
 639          it is legit for write do less than the whole amount specified.  */
 640       else if (nwrite != ret)
 641         {
 642           sprintf (buf,
 643                    "unexec write failure: addr 0x%x, fileno %d, size 0x%x, wrote 0x%x, errno %d",
 644                    ptr, new, nwrite, ret, errno);
 645           PERROR (buf);
 646         }
 647 #endif
 648       i += nwrite;
 649       ptr += nwrite;
 650     }
 651 }
 652 /* ****************************************************************
 653  * copy_text_and_data
 654  *
 655  * Copy the text and data segments from memory to the new a.out
 656  */
 657 static int
 658 copy_text_and_data (new, a_out)
 659      int new, a_out;
 660 {
 661   register char *end;
 662   register char *ptr;
 663
 664 #ifdef COFF
 665
 666 #ifdef MSDOS
 667 #if __DJGPP__ >= 2
 668   /* Dump the original table of exception handlers, not the one
 669      where our exception hooks are registered.  */
 670   __djgpp_exception_toggle ();
 671
 672   /* Switch off startup flags that might have been set at runtime
 673      and which might change the way that dumped Emacs works.  */
 674   save_djgpp_startup_flags = _crt0_startup_flags;
 675   _crt0_startup_flags &= ~(_CRT0_FLAG_NO_LFN | _CRT0_FLAG_NEARPTR);
 676 #endif
 677 #endif
 678
 679   lseek (new, (long) text_scnptr, 0);
 680   ptr = (char *) f_ohdr.text_start;
 681   end = ptr + f_ohdr.tsize;
 682   write_segment (new, ptr, end);
 683
 684   lseek (new, (long) data_scnptr, 0);
 685   ptr = (char *) f_ohdr.data_start;
 686   end = ptr + f_ohdr.dsize;
 687   write_segment (new, ptr, end);
 688
 689 #ifdef MSDOS
 690 #if __DJGPP__ >= 2
 691   /* Restore our exception hooks.  */
 692   __djgpp_exception_toggle ();
 693
 694   /* Restore the startup flags.  */
 695   _crt0_startup_flags = save_djgpp_startup_flags;
 696 #endif
 697 #endif
 698
 699 #else /* if not COFF */
 700
 701 /* Some machines count the header as part of the text segment.
 702    That is to say, the header appears in core
 703    just before the address that start_of_text returns.
 704    For them, N_TXTOFF is the place where the header goes.
 705    We must adjust the seek to the place after the header.
 706    Note that at this point hdr.a_text does *not* count
 707    the extra A_TEXT_OFFSET bytes, only the actual bytes of code.  */
 708
 709 #ifdef A_TEXT_SEEK
 710   lseek (new, (long) A_TEXT_SEEK (hdr), 0);
 711 #else
 712   lseek (new, (long) N_TXTOFF (hdr), 0);
 713 #endif /* no A_TEXT_SEEK */
 714
 715   ptr = (char *) unexec_text_start;
 716   end = ptr + hdr.a_text;
 717   write_segment (new, ptr, end);
 718
 719   ptr = (char *) unexec_data_start;
 720   end = ptr + hdr.a_data;
 721 /*  This lseek is certainly incorrect when A_TEXT_OFFSET
 722     and I believe it is a no-op otherwise.
 723     Let's see if its absence ever fails.  */
 724 /*  lseek (new, (long) N_TXTOFF (hdr) + hdr.a_text, 0); */
 725   write_segment (new, ptr, end);
 726
 727 #endif /* not COFF */
 728
 729   return 0;
 730 }
 731 \f
 732 /* ****************************************************************
 733  * copy_sym
 734  *
 735  * Copy the relocation information and symbol table from the a.out to the new
 736  */
 737 static int
 738 copy_sym (new, a_out, a_name, new_name)
 739      int new, a_out;
 740      char *a_name, *new_name;
 741 {
 742   char page[1024];
 743   int n;
 744
 745   if (a_out < 0)
 746     return 0;
 747
 748 #ifdef COFF
 749   if (SYMS_START == 0L)
 750     return 0;
 751 #endif  /* COFF */
 752
 753 #ifdef COFF
 754   if (lnnoptr)                  /* if there is line number info */
 755     lseek (a_out, coff_offset + lnnoptr, 0);    /* start copying from there */
 756   else
 757     lseek (a_out, coff_offset + SYMS_START, 0); /* Position a.out to symtab. */
 758 #else  /* not COFF */
 759   lseek (a_out, SYMS_START, 0); /* Position a.out to symtab. */
 760 #endif /* not COFF */
 761
 762   while ((n = read (a_out, page, sizeof page)) > 0)
 763     {
 764       if (write (new, page, n) != n)
 765         {
 766           PERROR (new_name);
 767         }
 768     }
 769   if (n < 0)
 770     {
 771       PERROR (a_name);
 772     }
 773   return 0;
 774 }
 775 \f
 776 /* ****************************************************************
 777  * mark_x
 778  *
 779  * After successfully building the new a.out, mark it executable
 780  */
 781 static void
 782 mark_x (name)
 783      char *name;
 784 {
 785   struct stat sbuf;
 786   int um;
 787   int new = 0;  /* for PERROR */
 788
 789   um = umask (777);
 790   umask (um);
 791   if (stat (name, &sbuf) == -1)
 792     {
 793       PERROR (name);
 794     }
 795   sbuf.st_mode |= 0111 & ~um;
 796   if (chmod (name, sbuf.st_mode) == -1)
 797     PERROR (name);
 798 }
 799 \f
 800 #ifdef COFF
 801 #ifndef COFF_BSD_SYMBOLS
 802
 803 /*
 804  *      If the COFF file contains a symbol table and a line number section,
 805  *      then any auxiliary entries that have values for x_lnnoptr must
 806  *      be adjusted by the amount that the line number section has moved
 807  *      in the file (bias computed in make_hdr).  The #@$%&* designers of
 808  *      the auxiliary entry structures used the absolute file offsets for
 809  *      the line number entry rather than an offset from the start of the
 810  *      line number section!
 811  *
 812  *      When I figure out how to scan through the symbol table and pick out
 813  *      the auxiliary entries that need adjustment, this routine will
 814  *      be fixed.  As it is now, all such entries are wrong and sdb
 815  *      will complain.   Fred Fish, UniSoft Systems Inc.
 816  */
 817
 818 /* This function is probably very slow.  Instead of reopening the new
 819    file for input and output it should copy from the old to the new
 820    using the two descriptors already open (WRITEDESC and READDESC).
 821    Instead of reading one small structure at a time it should use
 822    a reasonable size buffer.  But I don't have time to work on such
 823    things, so I am installing it as submitted to me.  -- RMS.  */
 824
 825 adjust_lnnoptrs (writedesc, readdesc, new_name)
 826      int writedesc;
 827      int readdesc;
 828      char *new_name;
 829 {
 830   register int nsyms;
 831   register int new;
 832   struct syment symentry;
 833   union auxent auxentry;
 834
 835   if (!lnnoptr || !f_hdr.f_symptr)
 836     return 0;
 837
 838 #ifdef MSDOS
 839   if ((new = writedesc) < 0)
 840 #else
 841   if ((new = open (new_name, O_RDWR)) < 0)
 842 #endif
 843     {
 844       PERROR (new_name);
 845       return -1;
 846     }
 847
 848   lseek (new, f_hdr.f_symptr, 0);
 849   for (nsyms = 0; nsyms < f_hdr.f_nsyms; nsyms++)
 850     {
 851       read (new, &symentry, SYMESZ);
 852       if (symentry.n_numaux)
 853         {
 854           read (new, &auxentry, AUXESZ);
 855           nsyms++;
 856           if (ISFCN (symentry.n_type) || symentry.n_type == 0x2400)
 857             {
 858               auxentry.x_sym.x_fcnary.x_fcn.x_lnnoptr += bias;
 859               lseek (new, -AUXESZ, 1);
 860               write (new, &auxentry, AUXESZ);
 861             }
 862         }
 863     }
 864 #ifndef MSDOS
 865   close (new);
 866 #endif
 867   return 0;
 868 }
 869
 870 #endif /* COFF_BSD_SYMBOLS */
 871
 872 #endif /* COFF */
 873
 874 /* ****************************************************************
 875  * unexec
 876  *
 877  * driving logic.
 878  */
 879 unexec (new_name, a_name, data_start, bss_start, entry_address)
 880      char *new_name, *a_name;
 881      unsigned data_start, bss_start, entry_address;
 882 {
 883   int new, a_out = -1;
 884
 885   if (a_name && (a_out = open (a_name, O_RDONLY)) < 0)
 886     {
 887       PERROR (a_name);
 888     }
 889   if ((new = creat (new_name, 0666)) < 0)
 890     {
 891       PERROR (new_name);
 892     }
 893
 894   if (make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name) < 0
 895       || copy_text_and_data (new, a_out) < 0
 896       || copy_sym (new, a_out, a_name, new_name) < 0
 897 #ifdef COFF
 898 #ifndef COFF_BSD_SYMBOLS
 899       || adjust_lnnoptrs (new, a_out, new_name) < 0
 900 #endif
 901 #endif
 902       )
 903     {
 904       close (new);
 905       /* unlink (new_name);             /* Failed, unlink new a.out */
 906       return -1;
 907     }
 908
 909   close (new);
 910   if (a_out >= 0)
 911     close (a_out);
 912   mark_x (new_name);
 913   return 0;
 914 }
 915
 916 #endif /* not CANNOT_DUMP */
 917
 918 /* arch-tag: 62409b69-e27a-4a7c-9413-0210d6b54e7f
 919    (do not change this comment) */