Merge from gnulib
[emacs.git] / src / unexaix.c
blobaf114e4427dc95650d4e97688d589af54ff241cb
1 /* Dump an executable image.
2 Copyright (C) 1985-1988, 1999, 2001-2015 Free Software Foundation,
3 Inc.
5 This file is part of GNU Emacs.
7 GNU Emacs is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 GNU Emacs is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
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 (const char *new_name, const *old_name);
36 * Takes a snapshot of the program and makes an a.out format file in the
37 * file named by the string argument new_name.
38 * If a_name is non-NULL, the symbol table will be taken from the given file.
39 * On some machines, an existing a_name file is required.
43 #include <config.h>
44 #include "unexec.h"
45 #include "lisp.h"
47 #define PERROR(file) report_error (file, new)
48 #include <a.out.h>
49 /* Define getpagesize () if the system does not.
50 Note that this may depend on symbols defined in a.out.h
52 #include "getpagesize.h"
54 #include <sys/types.h>
55 #include <inttypes.h>
56 #include <stdarg.h>
57 #include <stdio.h>
58 #include <errno.h>
59 #include <unistd.h>
60 #include <fcntl.h>
62 extern char _data[];
63 extern char _text[];
65 #include <filehdr.h>
66 #include <aouthdr.h>
67 #include <scnhdr.h>
68 #include <syms.h>
70 static struct filehdr f_hdr; /* File header */
71 static struct aouthdr f_ohdr; /* Optional file header (a.out) */
72 static off_t bias; /* Bias to add for growth */
73 static off_t lnnoptr; /* Pointer to line-number info within file */
75 static off_t text_scnptr;
76 static off_t data_scnptr;
77 #define ALIGN(val, pwr) (((val) + ((1L<<(pwr))-1)) & ~((1L<<(pwr))-1))
78 static off_t load_scnptr;
79 static off_t orig_load_scnptr;
80 static off_t orig_data_scnptr;
81 static int unrelocate_symbols (int, int, const char *, const char *);
83 #ifndef MAX_SECTIONS
84 #define MAX_SECTIONS 10
85 #endif
87 static int adjust_lnnoptrs (int, int, const char *);
89 static int pagemask;
91 #include "lisp.h"
93 static _Noreturn void
94 report_error (const char *file, int fd)
96 int err = errno;
97 if (fd)
98 emacs_close (fd);
99 report_file_errno ("Cannot unexec", build_string (file), err);
102 #define ERROR0(msg) report_error_1 (new, msg)
103 #define ERROR1(msg,x) report_error_1 (new, msg, x)
104 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y)
106 static _Noreturn void ATTRIBUTE_FORMAT_PRINTF (2, 3)
107 report_error_1 (int fd, const char *msg, ...)
109 va_list ap;
110 emacs_close (fd);
111 va_start (ap, msg);
112 verror (msg, ap);
113 va_end (ap);
116 static int make_hdr (int, int, const char *, const char *);
117 static void mark_x (const char *);
118 static int copy_text_and_data (int);
119 static int copy_sym (int, int, const char *, const char *);
120 static void write_segment (int, char *, char *);
122 /* ****************************************************************
123 * unexec
125 * driving logic.
127 void
128 unexec (const char *new_name, const char *a_name)
130 int new = -1, a_out = -1;
132 if (a_name && (a_out = emacs_open (a_name, O_RDONLY, 0)) < 0)
134 PERROR (a_name);
136 if ((new = emacs_open (new_name, O_WRONLY | O_CREAT | O_TRUNC, 0777)) < 0)
138 PERROR (new_name);
140 if (make_hdr (new, a_out,
141 a_name, new_name) < 0
142 || copy_text_and_data (new) < 0
143 || copy_sym (new, a_out, a_name, new_name) < 0
144 || adjust_lnnoptrs (new, a_out, new_name) < 0
145 || unrelocate_symbols (new, a_out, a_name, new_name) < 0)
147 emacs_close (new);
148 return;
151 emacs_close (new);
152 if (a_out >= 0)
153 emacs_close (a_out);
156 /* ****************************************************************
157 * make_hdr
159 * Make the header in the new a.out from the header in core.
160 * Modify the text and data sizes.
162 static int
163 make_hdr (int new, int a_out,
164 const char *a_name, const char *new_name)
166 int scns;
167 uintptr_t bss_start;
168 uintptr_t data_start;
170 struct scnhdr section[MAX_SECTIONS];
171 struct scnhdr * f_thdr; /* Text section header */
172 struct scnhdr * f_dhdr; /* Data section header */
173 struct scnhdr * f_bhdr; /* Bss section header */
174 struct scnhdr * f_lhdr; /* Loader section header */
175 struct scnhdr * f_tchdr; /* Typechk section header */
176 struct scnhdr * f_dbhdr; /* Debug section header */
177 struct scnhdr * f_xhdr; /* Except section header */
179 load_scnptr = orig_load_scnptr = lnnoptr = 0;
180 pagemask = getpagesize () - 1;
182 /* Adjust text/data boundary. */
183 data_start = (uintptr_t) _data;
185 data_start = data_start & ~pagemask; /* (Down) to page boundary. */
187 bss_start = (uintptr_t) sbrk (0) + pagemask;
188 bss_start &= ~ pagemask;
190 if (data_start > bss_start) /* Can't have negative data size. */
192 ERROR2 (("unexec: data_start (0x%"PRIxPTR
193 ") can't be greater than bss_start (0x%"PRIxPTR")"),
194 data_start, bss_start);
197 /* Salvage as much info from the existing file as possible */
198 f_thdr = NULL; f_dhdr = NULL; f_bhdr = NULL;
199 f_lhdr = NULL; f_tchdr = NULL; f_dbhdr = NULL; f_xhdr = NULL;
200 if (a_out >= 0)
202 if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
204 PERROR (a_name);
206 if (f_hdr.f_opthdr > 0)
208 if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
210 PERROR (a_name);
213 if (f_hdr.f_nscns > MAX_SECTIONS)
215 ERROR0 ("unexec: too many section headers -- increase MAX_SECTIONS");
217 /* Loop through section headers */
218 for (scns = 0; scns < f_hdr.f_nscns; scns++) {
219 struct scnhdr *s = &section[scns];
220 if (read (a_out, s, sizeof (*s)) != sizeof (*s))
222 PERROR (a_name);
225 #define CHECK_SCNHDR(ptr, name, flags) \
226 if (strcmp (s->s_name, name) == 0) { \
227 if (s->s_flags != flags) { \
228 fprintf (stderr, "unexec: %lx flags where %x expected in %s section.\n", \
229 (unsigned long)s->s_flags, flags, name); \
231 if (ptr) { \
232 fprintf (stderr, "unexec: duplicate section header for section %s.\n", \
233 name); \
235 ptr = s; \
237 CHECK_SCNHDR (f_thdr, _TEXT, STYP_TEXT);
238 CHECK_SCNHDR (f_dhdr, _DATA, STYP_DATA);
239 CHECK_SCNHDR (f_bhdr, _BSS, STYP_BSS);
240 CHECK_SCNHDR (f_lhdr, _LOADER, STYP_LOADER);
241 CHECK_SCNHDR (f_dbhdr, _DEBUG, STYP_DEBUG);
242 CHECK_SCNHDR (f_tchdr, _TYPCHK, STYP_TYPCHK);
243 CHECK_SCNHDR (f_xhdr, _EXCEPT, STYP_EXCEPT);
246 if (f_thdr == 0)
248 ERROR1 ("unexec: couldn't find \"%s\" section", (int) _TEXT);
250 if (f_dhdr == 0)
252 ERROR1 ("unexec: couldn't find \"%s\" section", (int) _DATA);
254 if (f_bhdr == 0)
256 ERROR1 ("unexec: couldn't find \"%s\" section", (int) _BSS);
259 else
261 ERROR0 ("can't build a COFF file from scratch yet");
263 orig_data_scnptr = f_dhdr->s_scnptr;
264 orig_load_scnptr = f_lhdr ? f_lhdr->s_scnptr : 0;
266 /* Now we alter the contents of all the f_*hdr variables
267 to correspond to what we want to dump. */
269 /* Indicate that the reloc information is no longer valid for ld (bind);
270 we only update it enough to fake out the exec-time loader. */
271 f_hdr.f_flags |= (F_RELFLG | F_EXEC);
273 f_ohdr.dsize = bss_start - f_ohdr.data_start;
274 f_ohdr.bsize = 0;
276 f_dhdr->s_size = f_ohdr.dsize;
277 f_bhdr->s_size = f_ohdr.bsize;
278 f_bhdr->s_paddr = f_ohdr.data_start + f_ohdr.dsize;
279 f_bhdr->s_vaddr = f_ohdr.data_start + f_ohdr.dsize;
281 /* fix scnptr's */
283 off_t ptr = section[0].s_scnptr;
285 bias = -1;
286 for (scns = 0; scns < f_hdr.f_nscns; scns++)
288 struct scnhdr *s = &section[scns];
290 if (s->s_flags & STYP_PAD) /* .pad sections omitted in AIX 4.1 */
293 * the text_start should probably be o_algntext but that doesn't
294 * seem to change
296 if (f_ohdr.text_start != 0) /* && scns != 0 */
298 s->s_size = 512 - (ptr % 512);
299 if (s->s_size == 512)
300 s->s_size = 0;
302 s->s_scnptr = ptr;
304 else if (s->s_flags & STYP_DATA)
305 s->s_scnptr = ptr;
306 else if (!(s->s_flags & (STYP_TEXT | STYP_BSS)))
308 if (bias == -1) /* if first section after bss */
309 bias = ptr - s->s_scnptr;
311 s->s_scnptr += bias;
312 ptr = s->s_scnptr;
315 ptr = ptr + s->s_size;
319 /* fix other pointers */
320 for (scns = 0; scns < f_hdr.f_nscns; scns++)
322 struct scnhdr *s = &section[scns];
324 if (s->s_relptr != 0)
326 s->s_relptr += bias;
328 if (s->s_lnnoptr != 0)
330 if (lnnoptr == 0) lnnoptr = s->s_lnnoptr;
331 s->s_lnnoptr += bias;
335 if (f_hdr.f_symptr > 0L)
337 f_hdr.f_symptr += bias;
340 text_scnptr = f_thdr->s_scnptr;
341 data_scnptr = f_dhdr->s_scnptr;
342 load_scnptr = f_lhdr ? f_lhdr->s_scnptr : 0;
344 if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr))
346 PERROR (new_name);
349 if (f_hdr.f_opthdr > 0)
351 if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr))
353 PERROR (new_name);
357 for (scns = 0; scns < f_hdr.f_nscns; scns++) {
358 struct scnhdr *s = &section[scns];
359 if (write (new, s, sizeof (*s)) != sizeof (*s))
361 PERROR (new_name);
365 return (0);
368 /* ****************************************************************
371 * Copy the text and data segments from memory to the new a.out
373 static int
374 copy_text_and_data (int new)
376 char *end;
377 char *ptr;
379 lseek (new, text_scnptr, SEEK_SET);
380 ptr = _text;
381 end = ptr + f_ohdr.tsize;
382 write_segment (new, ptr, end);
384 lseek (new, data_scnptr, SEEK_SET);
385 ptr = (char *) f_ohdr.data_start;
386 end = ptr + f_ohdr.dsize;
387 write_segment (new, ptr, end);
389 return 0;
392 #define UnexBlockSz (1<<12) /* read/write block size */
393 static void
394 write_segment (int new, char *ptr, char *end)
396 int i, nwrite, ret;
397 char zeros[UnexBlockSz];
399 for (i = 0; ptr < end;)
401 /* distance to next block. */
402 nwrite = (((int) ptr + UnexBlockSz) & -UnexBlockSz) - (int) ptr;
403 /* But not beyond specified end. */
404 if (nwrite > end - ptr) nwrite = end - ptr;
405 ret = write (new, ptr, nwrite);
406 /* If write gets a page fault, it means we reached
407 a gap between the old text segment and the old data segment.
408 This gap has probably been remapped into part of the text segment.
409 So write zeros for it. */
410 if (ret == -1 && errno == EFAULT)
412 memset (zeros, 0, nwrite);
413 write (new, zeros, nwrite);
415 else if (nwrite != ret)
417 int write_errno = errno;
418 char buf[1000];
419 void *addr = ptr;
420 sprintf (buf,
421 "unexec write failure: addr %p, fileno %d, size 0x%x, wrote 0x%x, errno %d",
422 addr, new, nwrite, ret, errno);
423 errno = write_errno;
424 PERROR (buf);
426 i += nwrite;
427 ptr += nwrite;
431 /* ****************************************************************
432 * copy_sym
434 * Copy the relocation information and symbol table from the a.out to the new
436 static int
437 copy_sym (int new, int a_out, const char *a_name, const char *new_name)
439 char page[UnexBlockSz];
440 int n;
442 if (a_out < 0)
443 return 0;
445 if (orig_load_scnptr == 0L)
446 return 0;
448 if (lnnoptr && lnnoptr < orig_load_scnptr) /* if there is line number info */
449 lseek (a_out, lnnoptr, SEEK_SET); /* start copying from there */
450 else
451 lseek (a_out, orig_load_scnptr, SEEK_SET); /* Position a.out to symtab. */
453 while ((n = read (a_out, page, sizeof page)) > 0)
455 if (write (new, page, n) != n)
457 PERROR (new_name);
460 if (n < 0)
462 PERROR (a_name);
464 return 0;
467 static int
468 adjust_lnnoptrs (int writedesc, int readdesc, const char *new_name)
470 int nsyms;
471 int naux;
472 int new;
473 struct syment symentry;
474 union auxent auxentry;
476 if (!lnnoptr || !f_hdr.f_symptr)
477 return 0;
479 if ((new = emacs_open (new_name, O_RDWR, 0)) < 0)
481 PERROR (new_name);
482 return -1;
485 lseek (new, f_hdr.f_symptr, SEEK_SET);
486 for (nsyms = 0; nsyms < f_hdr.f_nsyms; nsyms++)
488 read (new, &symentry, SYMESZ);
489 if (symentry.n_sclass == C_BINCL || symentry.n_sclass == C_EINCL)
491 symentry.n_value += bias;
492 lseek (new, -SYMESZ, SEEK_CUR);
493 write (new, &symentry, SYMESZ);
496 for (naux = symentry.n_numaux; naux-- != 0; )
498 read (new, &auxentry, AUXESZ);
499 nsyms++;
500 if (naux != 0 /* skip csect auxentry (last entry) */
501 && (symentry.n_sclass == C_EXT || symentry.n_sclass == C_HIDEXT))
503 auxentry.x_sym.x_fcnary.x_fcn.x_lnnoptr += bias;
504 lseek (new, -AUXESZ, SEEK_CUR);
505 write (new, &auxentry, AUXESZ);
509 emacs_close (new);
511 return 0;
514 static int
515 unrelocate_symbols (int new, int a_out,
516 const char *a_name, const char *new_name)
518 int i;
519 LDHDR ldhdr;
520 LDREL ldrel;
521 off_t t_reloc = (intptr_t) _text - f_ohdr.text_start;
522 #ifndef ALIGN_DATA_RELOC
523 off_t d_reloc = (intptr_t) _data - f_ohdr.data_start;
524 #else
525 /* This worked (and was needed) before AIX 4.2.
526 I have no idea why. -- Mike */
527 off_t d_reloc = (intptr_t) _data - ALIGN (f_ohdr.data_start, 2);
528 #endif
529 int * p;
531 if (load_scnptr == 0)
532 return 0;
534 lseek (a_out, orig_load_scnptr, SEEK_SET);
535 if (read (a_out, &ldhdr, sizeof (ldhdr)) != sizeof (ldhdr))
537 PERROR (new_name);
540 #define SYMNDX_TEXT 0
541 #define SYMNDX_DATA 1
542 #define SYMNDX_BSS 2
544 for (i = 0; i < ldhdr.l_nreloc; i++)
546 lseek (a_out,
547 orig_load_scnptr + LDHDRSZ + LDSYMSZ*ldhdr.l_nsyms + LDRELSZ*i,
548 SEEK_SET);
550 if (read (a_out, &ldrel, LDRELSZ) != LDRELSZ)
552 PERROR (a_name);
555 /* move the BSS loader symbols to the DATA segment */
556 if (ldrel.l_symndx == SYMNDX_BSS)
558 ldrel.l_symndx = SYMNDX_DATA;
560 lseek (new,
561 load_scnptr + LDHDRSZ + LDSYMSZ*ldhdr.l_nsyms + LDRELSZ*i,
562 SEEK_SET);
564 if (write (new, &ldrel, LDRELSZ) != LDRELSZ)
566 PERROR (new_name);
570 if (ldrel.l_rsecnm == f_ohdr.o_sndata)
572 int orig_int;
574 lseek (a_out,
575 orig_data_scnptr + (ldrel.l_vaddr - f_ohdr.data_start),
576 SEEK_SET);
578 if (read (a_out, (void *) &orig_int, sizeof (orig_int))
579 != sizeof (orig_int))
581 PERROR (a_name);
584 p = (int *) (intptr_t) (ldrel.l_vaddr + d_reloc);
586 switch (ldrel.l_symndx) {
587 case SYMNDX_TEXT:
588 orig_int = * p - t_reloc;
589 break;
591 case SYMNDX_DATA:
592 case SYMNDX_BSS:
593 orig_int = * p - d_reloc;
594 break;
597 if (orig_int != * p)
599 lseek (new,
600 data_scnptr + (ldrel.l_vaddr - f_ohdr.data_start),
601 SEEK_SET);
602 if (write (new, (void *) &orig_int, sizeof (orig_int))
603 != sizeof (orig_int))
605 PERROR (new_name);
610 return 0;