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[emacs.git] / src / unexaix.c
blob17df5b5174ba6b4c9b5a3bd0b0fc2d2ae68c9ac5
1 /* Dump an executable image.
2 Copyright (C) 1985, 1986, 1987, 1988, 1999 Free Software Foundation, Inc.
4 This file is part of GNU Emacs.
6 GNU Emacs is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
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.
16 You should have received a copy of the GNU General Public License
17 along with GNU Emacs; see the file COPYING. If not, write to
18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA.
21 In other words, you are welcome to use, share and improve this program.
22 You are forbidden to forbid anyone else to use, share and improve
23 what you give them. Help stamp out software-hoarding! */
26 /* Originally based on the COFF unexec.c by Spencer W. Thomas.
28 * Subsequently hacked on by
29 * Bill Mann <Bill_Man@praxisint.com>
30 * Andrew Vignaux <Andrew.Vignaux@comp.vuw.ac.nz>
31 * Mike Sperber <sperber@informatik.uni-tuebingen.de>
33 * Synopsis:
34 * unexec (new_name, a_name, data_start, bss_start, entry_address)
35 * char *new_name, *a_name;
36 * unsigned data_start, bss_start, entry_address;
38 * Takes a snapshot of the program and makes an a.out format file in the
39 * file named by the string argument new_name.
40 * If a_name is non-NULL, the symbol table will be taken from the given file.
41 * On some machines, an existing a_name file is required.
43 * data_start and entry_address are ignored.
45 * bss_start indicates how much of the data segment is to be saved in the
46 * a.out file and restored when the program is executed. It gives the lowest
47 * unsaved address, and is rounded up to a page boundary. The default when 0
48 * is given assumes that the entire data segment is to be stored, including
49 * the previous data and bss as well as any additional storage allocated with
50 * sbrk(2).
54 #ifndef emacs
55 #define PERROR(arg) perror (arg); return -1
56 #else
57 #include <config.h>
58 #define PERROR(file) report_error (file, new)
59 #endif
61 #include <a.out.h>
62 /* Define getpagesize () if the system does not.
63 Note that this may depend on symbols defined in a.out.h
65 #include "getpagesize.h"
67 #include <sys/types.h>
68 #include <stdio.h>
69 #include <sys/stat.h>
70 #include <errno.h>
71 #include <unistd.h>
72 #include <fcntl.h>
74 extern char *start_of_text (void); /* Start of text */
75 extern char *start_of_data (void); /* Start of initialized data */
77 extern int _data;
78 extern int _text;
80 #include <filehdr.h>
81 #include <aouthdr.h>
82 #include <scnhdr.h>
83 #include <syms.h>
85 static struct filehdr f_hdr; /* File header */
86 static struct aouthdr f_ohdr; /* Optional file header (a.out) */
87 static long bias; /* Bias to add for growth */
88 static long lnnoptr; /* Pointer to line-number info within file */
90 static long text_scnptr;
91 static long data_scnptr;
92 #define ALIGN(val, pwr) (((val) + ((1L<<(pwr))-1)) & ~((1L<<(pwr))-1))
93 static long load_scnptr;
94 static long orig_load_scnptr;
95 static long orig_data_scnptr;
96 static int unrelocate_symbols (int, int, char *, char *);
98 #ifndef MAX_SECTIONS
99 #define MAX_SECTIONS 10
100 #endif
102 static int adjust_lnnoptrs (int, int, char *);
104 static int pagemask;
106 /* Correct an int which is the bit pattern of a pointer to a byte
107 into an int which is the number of a byte.
108 This is a no-op on ordinary machines, but not on all. */
110 #ifndef ADDR_CORRECT /* Let m-*.h files override this definition */
111 #define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
112 #endif
114 #ifdef emacs
115 #include "lisp.h"
117 static void
118 report_error (char *file, int fd)
120 if (fd)
121 close (fd);
122 report_file_error ("Cannot unexec", Fcons (build_string (file), Qnil));
124 #endif /* emacs */
126 #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
127 #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
128 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
130 static void
131 report_error_1 (int fd, char *msg, int a1, int a2)
133 close (fd);
134 #ifdef emacs
135 error (msg, a1, a2);
136 #else
137 fprintf (stderr, msg, a1, a2);
138 fprintf (stderr, "\n");
139 #endif
142 static int make_hdr (int, int, unsigned, unsigned, unsigned, char *, char *);
143 static void mark_x (char *);
144 static int copy_text_and_data (int);
145 static int copy_sym (int, int, char *, char *);
146 static void write_segment (int, char *, char *);
148 /* ****************************************************************
149 * unexec
151 * driving logic.
153 int unexec (char *new_name, char *a_name,
154 unsigned data_start,
155 unsigned bss_start,
156 unsigned entry_address)
158 int new = -1, a_out = -1;
160 if (a_name && (a_out = open (a_name, O_RDONLY)) < 0)
162 PERROR (a_name);
164 if ((new = creat (new_name, 0666)) < 0)
166 PERROR (new_name);
168 if (make_hdr (new, a_out,
169 data_start, bss_start,
170 entry_address,
171 a_name, new_name) < 0
172 || copy_text_and_data (new) < 0
173 || copy_sym (new, a_out, a_name, new_name) < 0
174 || adjust_lnnoptrs (new, a_out, new_name) < 0
175 || unrelocate_symbols (new, a_out, a_name, new_name) < 0)
177 close (new);
178 return -1;
181 close (new);
182 if (a_out >= 0)
183 close (a_out);
184 mark_x (new_name);
185 return 0;
188 /* ****************************************************************
189 * make_hdr
191 * Make the header in the new a.out from the header in core.
192 * Modify the text and data sizes.
194 static int
195 make_hdr (int new, int a_out,
196 unsigned data_start, unsigned bss_start,
197 unsigned entry_address,
198 char *a_name, char *new_name)
200 int scns;
201 unsigned int bss_end;
203 struct scnhdr section[MAX_SECTIONS];
204 struct scnhdr * f_thdr; /* Text section header */
205 struct scnhdr * f_dhdr; /* Data section header */
206 struct scnhdr * f_bhdr; /* Bss section header */
207 struct scnhdr * f_lhdr; /* Loader section header */
208 struct scnhdr * f_tchdr; /* Typechk section header */
209 struct scnhdr * f_dbhdr; /* Debug section header */
210 struct scnhdr * f_xhdr; /* Except section header */
212 load_scnptr = orig_load_scnptr = lnnoptr = 0;
213 pagemask = getpagesize () - 1;
215 /* Adjust text/data boundary. */
216 data_start = (long) start_of_data ();
217 data_start = ADDR_CORRECT (data_start);
219 data_start = data_start & ~pagemask; /* (Down) to page boundary. */
221 bss_end = ADDR_CORRECT (sbrk (0)) + pagemask;
222 bss_end &= ~ pagemask;
223 /* Adjust data/bss boundary. */
224 if (bss_start != 0)
226 bss_start = (ADDR_CORRECT (bss_start) + pagemask);
227 /* (Up) to page bdry. */
228 bss_start &= ~ pagemask;
229 if (bss_start > bss_end)
231 ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
232 bss_start);
235 else
236 bss_start = bss_end;
238 if (data_start > bss_start) /* Can't have negative data size. */
240 ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
241 data_start, bss_start);
244 /* Salvage as much info from the existing file as possible */
245 f_thdr = NULL; f_dhdr = NULL; f_bhdr = NULL;
246 f_lhdr = NULL; f_tchdr = NULL; f_dbhdr = NULL; f_xhdr = NULL;
247 if (a_out >= 0)
249 if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
251 PERROR (a_name);
253 if (f_hdr.f_opthdr > 0)
255 if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
257 PERROR (a_name);
260 if (f_hdr.f_nscns > MAX_SECTIONS)
262 ERROR0 ("unexec: too many section headers -- increase MAX_SECTIONS");
264 /* Loop through section headers */
265 for (scns = 0; scns < f_hdr.f_nscns; scns++) {
266 struct scnhdr *s = &section[scns];
267 if (read (a_out, s, sizeof (*s)) != sizeof (*s))
269 PERROR (a_name);
272 #define CHECK_SCNHDR(ptr, name, flags) \
273 if (strcmp(s->s_name, name) == 0) { \
274 if (s->s_flags != flags) { \
275 fprintf(stderr, "unexec: %lx flags where %x expected in %s section.\n", \
276 (unsigned long)s->s_flags, flags, name); \
278 if (ptr) { \
279 fprintf(stderr, "unexec: duplicate section header for section %s.\n", \
280 name); \
282 ptr = s; \
284 CHECK_SCNHDR(f_thdr, _TEXT, STYP_TEXT);
285 CHECK_SCNHDR(f_dhdr, _DATA, STYP_DATA);
286 CHECK_SCNHDR(f_bhdr, _BSS, STYP_BSS);
287 CHECK_SCNHDR(f_lhdr, _LOADER, STYP_LOADER);
288 CHECK_SCNHDR(f_dbhdr, _DEBUG, STYP_DEBUG);
289 CHECK_SCNHDR(f_tchdr, _TYPCHK, STYP_TYPCHK);
290 CHECK_SCNHDR(f_xhdr, _EXCEPT, STYP_EXCEPT);
293 if (f_thdr == 0)
295 ERROR1 ("unexec: couldn't find \"%s\" section", (int) _TEXT);
297 if (f_dhdr == 0)
299 ERROR1 ("unexec: couldn't find \"%s\" section", (int) _DATA);
301 if (f_bhdr == 0)
303 ERROR1 ("unexec: couldn't find \"%s\" section", (int) _BSS);
306 else
308 ERROR0 ("can't build a COFF file from scratch yet");
310 orig_data_scnptr = f_dhdr->s_scnptr;
311 orig_load_scnptr = f_lhdr ? f_lhdr->s_scnptr : 0;
313 /* Now we alter the contents of all the f_*hdr variables
314 to correspond to what we want to dump. */
316 /* Indicate that the reloc information is no longer valid for ld (bind);
317 we only update it enough to fake out the exec-time loader. */
318 f_hdr.f_flags |= (F_RELFLG | F_EXEC);
320 f_ohdr.dsize = bss_start - f_ohdr.data_start;
321 f_ohdr.bsize = bss_end - bss_start;
323 f_dhdr->s_size = f_ohdr.dsize;
324 f_bhdr->s_size = f_ohdr.bsize;
325 f_bhdr->s_paddr = f_ohdr.data_start + f_ohdr.dsize;
326 f_bhdr->s_vaddr = f_ohdr.data_start + f_ohdr.dsize;
328 /* fix scnptr's */
330 ulong ptr = section[0].s_scnptr;
332 bias = -1;
333 for (scns = 0; scns < f_hdr.f_nscns; scns++)
335 struct scnhdr *s = &section[scns];
337 if (s->s_flags & STYP_PAD) /* .pad sections omitted in AIX 4.1 */
340 * the text_start should probably be o_algntext but that doesn't
341 * seem to change
343 if (f_ohdr.text_start != 0) /* && scns != 0 */
345 s->s_size = 512 - (ptr % 512);
346 if (s->s_size == 512)
347 s->s_size = 0;
349 s->s_scnptr = ptr;
351 else if (s->s_flags & STYP_DATA)
352 s->s_scnptr = ptr;
353 else if (!(s->s_flags & (STYP_TEXT | STYP_BSS)))
355 if (bias == -1) /* if first section after bss */
356 bias = ptr - s->s_scnptr;
358 s->s_scnptr += bias;
359 ptr = s->s_scnptr;
362 ptr = ptr + s->s_size;
366 /* fix other pointers */
367 for (scns = 0; scns < f_hdr.f_nscns; scns++)
369 struct scnhdr *s = &section[scns];
371 if (s->s_relptr != 0)
373 s->s_relptr += bias;
375 if (s->s_lnnoptr != 0)
377 if (lnnoptr == 0) lnnoptr = s->s_lnnoptr;
378 s->s_lnnoptr += bias;
382 if (f_hdr.f_symptr > 0L)
384 f_hdr.f_symptr += bias;
387 text_scnptr = f_thdr->s_scnptr;
388 data_scnptr = f_dhdr->s_scnptr;
389 load_scnptr = f_lhdr ? f_lhdr->s_scnptr : 0;
391 if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
393 PERROR (new_name);
396 if (f_hdr.f_opthdr > 0)
398 if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
400 PERROR (new_name);
404 for (scns = 0; scns < f_hdr.f_nscns; scns++) {
405 struct scnhdr *s = &section[scns];
406 if (write (new, s, sizeof (*s)) != sizeof (*s))
408 PERROR (new_name);
412 return (0);
415 /* ****************************************************************
418 * Copy the text and data segments from memory to the new a.out
420 static int
421 copy_text_and_data (int new)
423 char *end;
424 char *ptr;
426 lseek (new, (long) text_scnptr, SEEK_SET);
427 ptr = start_of_text () + text_scnptr;
428 end = ptr + f_ohdr.tsize;
429 write_segment (new, ptr, end);
431 lseek (new, (long) data_scnptr, SEEK_SET);
432 ptr = (char *) f_ohdr.data_start;
433 end = ptr + f_ohdr.dsize;
434 write_segment (new, ptr, end);
436 return 0;
439 #define UnexBlockSz (1<<12) /* read/write block size */
440 static void
441 write_segment (int new, char *ptr, char *end)
443 int i, nwrite, ret;
444 char buf[80];
445 extern int errno;
446 char zeros[UnexBlockSz];
448 for (i = 0; ptr < end;)
450 /* distance to next block. */
451 nwrite = (((int) ptr + UnexBlockSz) & -UnexBlockSz) - (int) ptr;
452 /* But not beyond specified end. */
453 if (nwrite > end - ptr) nwrite = end - ptr;
454 ret = write (new, ptr, nwrite);
455 /* If write gets a page fault, it means we reached
456 a gap between the old text segment and the old data segment.
457 This gap has probably been remapped into part of the text segment.
458 So write zeros for it. */
459 if (ret == -1 && errno == EFAULT)
461 memset (zeros, 0, nwrite);
462 write (new, zeros, nwrite);
464 else if (nwrite != ret)
466 sprintf (buf,
467 "unexec write failure: addr 0x%lx, fileno %d, size 0x%x, wrote 0x%x, errno %d",
468 (unsigned long)ptr, new, nwrite, ret, errno);
469 PERROR (buf);
471 i += nwrite;
472 ptr += nwrite;
476 /* ****************************************************************
477 * copy_sym
479 * Copy the relocation information and symbol table from the a.out to the new
481 static int
482 copy_sym (int new, int a_out, char *a_name, char *new_name)
484 char page[UnexBlockSz];
485 int n;
487 if (a_out < 0)
488 return 0;
490 if (orig_load_scnptr == 0L)
491 return 0;
493 if (lnnoptr && lnnoptr < orig_load_scnptr) /* if there is line number info */
494 lseek (a_out, lnnoptr, SEEK_SET); /* start copying from there */
495 else
496 lseek (a_out, orig_load_scnptr, SEEK_SET); /* Position a.out to symtab. */
498 while ((n = read (a_out, page, sizeof page)) > 0)
500 if (write (new, page, n) != n)
502 PERROR (new_name);
505 if (n < 0)
507 PERROR (a_name);
509 return 0;
512 /* ****************************************************************
513 * mark_x
515 * After successfully building the new a.out, mark it executable
517 static void
518 mark_x (char *name)
520 struct stat sbuf;
521 int um;
522 int new = 0; /* for PERROR */
524 um = umask (777);
525 umask (um);
526 if (stat (name, &sbuf) == -1)
528 PERROR (name);
530 sbuf.st_mode |= 0111 & ~um;
531 if (chmod (name, sbuf.st_mode) == -1)
532 PERROR (name);
535 static int
536 adjust_lnnoptrs (int writedesc, int readdesc, char *new_name)
538 int nsyms;
539 int naux;
540 int new;
541 struct syment symentry;
542 union auxent auxentry;
544 if (!lnnoptr || !f_hdr.f_symptr)
545 return 0;
547 if ((new = open (new_name, O_RDWR)) < 0)
549 PERROR (new_name);
550 return -1;
553 lseek (new, f_hdr.f_symptr, SEEK_SET);
554 for (nsyms = 0; nsyms < f_hdr.f_nsyms; nsyms++)
556 read (new, &symentry, SYMESZ);
557 if (symentry.n_sclass == C_BINCL || symentry.n_sclass == C_EINCL)
559 symentry.n_value += bias;
560 lseek (new, -SYMESZ, SEEK_CUR);
561 write (new, &symentry, SYMESZ);
564 for (naux = symentry.n_numaux; naux-- != 0; )
566 read (new, &auxentry, AUXESZ);
567 nsyms++;
568 if (naux != 0 /* skip csect auxentry (last entry) */
569 && (symentry.n_sclass == C_EXT || symentry.n_sclass == C_HIDEXT))
571 auxentry.x_sym.x_fcnary.x_fcn.x_lnnoptr += bias;
572 lseek (new, -AUXESZ, SEEK_CUR);
573 write (new, &auxentry, AUXESZ);
577 close (new);
579 return 0;
582 static int
583 unrelocate_symbols (int new, int a_out, char *a_name, char *new_name)
585 int i;
586 LDHDR ldhdr;
587 LDREL ldrel;
588 ulong t_reloc = (ulong) &_text - f_ohdr.text_start;
589 #ifndef ALIGN_DATA_RELOC
590 ulong d_reloc = (ulong) &_data - f_ohdr.data_start;
591 #else
592 /* This worked (and was needed) before AIX 4.2.
593 I have no idea why. -- Mike */
594 ulong d_reloc = (ulong) &_data - ALIGN(f_ohdr.data_start, 2);
595 #endif
596 int * p;
598 if (load_scnptr == 0)
599 return 0;
601 lseek (a_out, orig_load_scnptr, SEEK_SET);
602 if (read (a_out, &ldhdr, sizeof (ldhdr)) != sizeof (ldhdr))
604 PERROR (new_name);
607 #define SYMNDX_TEXT 0
608 #define SYMNDX_DATA 1
609 #define SYMNDX_BSS 2
611 for (i = 0; i < ldhdr.l_nreloc; i++)
613 lseek (a_out,
614 orig_load_scnptr + LDHDRSZ + LDSYMSZ*ldhdr.l_nsyms + LDRELSZ*i,
615 SEEK_SET);
617 if (read (a_out, &ldrel, LDRELSZ) != LDRELSZ)
619 PERROR (a_name);
622 /* move the BSS loader symbols to the DATA segment */
623 if (ldrel.l_symndx == SYMNDX_BSS)
625 ldrel.l_symndx = SYMNDX_DATA;
627 lseek (new,
628 load_scnptr + LDHDRSZ + LDSYMSZ*ldhdr.l_nsyms + LDRELSZ*i,
629 SEEK_SET);
631 if (write (new, &ldrel, LDRELSZ) != LDRELSZ)
633 PERROR (new_name);
637 if (ldrel.l_rsecnm == f_ohdr.o_sndata)
639 int orig_int;
641 lseek (a_out,
642 orig_data_scnptr + (ldrel.l_vaddr - f_ohdr.data_start),
643 SEEK_SET);
645 if (read (a_out, (void *) &orig_int, sizeof (orig_int))
646 != sizeof (orig_int))
648 PERROR (a_name);
651 p = (int *) (ldrel.l_vaddr + d_reloc);
653 switch (ldrel.l_symndx) {
654 case SYMNDX_TEXT:
655 orig_int = * p - t_reloc;
656 break;
658 case SYMNDX_DATA:
659 case SYMNDX_BSS:
660 orig_int = * p - d_reloc;
661 break;
664 if (orig_int != * p)
666 lseek (new,
667 data_scnptr + (ldrel.l_vaddr - f_ohdr.data_start),
668 SEEK_SET);
669 if (write (new, (void *) &orig_int, sizeof (orig_int))
670 != sizeof (orig_int))
672 PERROR (new_name);
677 return 0;