1 /* Modified by Andrew.Vignaux@comp.vuw.ac.nz to get it to work :-) */
3 /* Copyright (C) 1985, 1986, 1987, 1988 Free Software Foundation, 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 2, or (at your option)
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; see the file COPYING. If not, write to
19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA.
22 In other words, you are welcome to use, share and improve this program.
23 You are forbidden to forbid anyone else to use, share and improve
24 what you give them. Help stamp out software-hoarding! */
28 * unexec.c - Convert a running program into an a.out file.
30 * Author: Spencer W. Thomas
31 * Computer Science Dept.
33 * Date: Tue Mar 2 1982
34 * Modified heavily since then.
36 * Updated for AIX 4.1.3 by Bill_Mann @ PraxisInt.com, Feb 1996
37 * As of AIX 4.1, text, data, and bss are pre-relocated by the binder in
38 * such a way that the file can be mapped with code in one segment and
39 * data/bss in another segment, without reading or copying the file, by
40 * the AIX exec loader. Padding sections are omitted, nevertheless
41 * small amounts of 'padding' still occurs between sections in the file.
42 * As modified, this code handles both 3.2 and 4.1 conventions.
45 * unexec (new_name, a_name, data_start, bss_start, entry_address)
46 * char *new_name, *a_name;
47 * unsigned data_start, bss_start, entry_address;
49 * Takes a snapshot of the program and makes an a.out format file in the
50 * file named by the string argument new_name.
51 * If a_name is non-NULL, the symbol table will be taken from the given file.
52 * On some machines, an existing a_name file is required.
54 * The boundaries within the a.out file may be adjusted with the data_start
55 * and bss_start arguments. Either or both may be given as 0 for defaults.
57 * Data_start gives the boundary between the text segment and the data
58 * segment of the program. The text segment can contain shared, read-only
59 * program code and literal data, while the data segment is always unshared
60 * and unprotected. Data_start gives the lowest unprotected address.
61 * The value you specify may be rounded down to a suitable boundary
62 * as required by the machine you are using.
64 * Specifying zero for data_start means the boundary between text and data
65 * should not be the same as when the program was loaded.
66 * If NO_REMAP is defined, the argument data_start is ignored and the
67 * segment boundaries are never changed.
69 * Bss_start indicates how much of the data segment is to be saved in the
70 * a.out file and restored when the program is executed. It gives the lowest
71 * unsaved address, and is rounded up to a page boundary. The default when 0
72 * is given assumes that the entire data segment is to be stored, including
73 * the previous data and bss as well as any additional storage allocated with
76 * The new file is set up to start at entry_address.
78 * If you make improvements I'd like to get them too.
79 * harpo!utah-cs!thomas, thomas@Utah-20
83 /* There are several compilation parameters affecting unexec:
87 Define this if your system uses COFF for executables.
88 Otherwise we assume you use Berkeley format.
92 Define this if you do not want to try to save Emacs's pure data areas
93 as part of the text segment.
95 Saving them as text is good because it allows users to share more.
97 However, on machines that locate the text area far from the data area,
98 the boundary cannot feasibly be moved. Such machines require
101 Also, remapping can cause trouble with the built-in startup routine
102 /lib/crt0.o, which defines `environ' as an initialized variable.
103 Dumping `environ' as pure does not work! So, to use remapping,
104 you must write a startup routine for your machine in Emacs's crt0.c.
105 If NO_REMAP is defined, Emacs uses the system's crt0.o.
109 Some machines that use COFF executables require that each section
110 start on a certain boundary *in the COFF file*. Such machines should
111 define SECTION_ALIGNMENT to a mask of the low-order bits that must be
112 zero on such a boundary. This mask is used to control padding between
113 segments in the COFF file.
115 If SECTION_ALIGNMENT is not defined, the segments are written
116 consecutively with no attempt at alignment. This is right for
121 Some machines require that the beginnings and ends of segments
122 *in core* be on certain boundaries. For most machines, a page
123 boundary is sufficient. That is the default. When a larger
124 boundary is needed, define SEGMENT_MASK to a mask of
125 the bits that must be zero on such a boundary.
129 Some machines count the a.out header as part of the size of the text
130 segment (a_text); they may actually load the header into core as the
131 first data in the text segment. Some have additional padding between
132 the header and the real text of the program that is counted in a_text.
134 For these machines, define A_TEXT_OFFSET(HDR) to examine the header
135 structure HDR and return the number of bytes to add to `a_text'
136 before writing it (above and beyond the number of bytes of actual
137 program text). HDR's standard fields are already correct, except that
138 this adjustment to the `a_text' field has not yet been made;
139 thus, the amount of offset can depend on the data in the file.
143 If defined, this macro specifies the number of bytes to seek into the
144 a.out file before starting to write the text segment.a
148 For machines using COFF, this macro, if defined, is a value stored
149 into the magic number field of the output file.
153 This macro can be used to generate statements to adjust or
154 initialize nonstandard fields in the file header
158 Macro to correct an int which is the bit pattern of a pointer to a byte
159 into an int which is the number of a byte.
161 This macro has a default definition which is usually right.
162 This default definition is a no-op on most machines (where a
163 pointer looks like an int) but not on all machines.
172 #define PERROR(arg) perror (arg); return -1
175 #define PERROR(file) report_error (file, new)
179 /* Define getpagesize () if the system does not.
180 Note that this may depend on symbols defined in a.out.h
182 #include "getpagesize.h"
184 #ifndef makedev /* Try to detect types.h already loaded */
185 #include <sys/types.h>
188 #include <sys/stat.h>
191 extern char *start_of_text (); /* Start of text */
192 extern char *start_of_data (); /* Start of initialized data */
204 /* I have a suspicion that these are turned off on all systems
205 and can be deleted. Try it in version 19. */
210 #endif /* not sun386 */
211 #endif /* not UMAX */
212 #endif /* Not STRIDE */
214 static struct filehdr f_hdr
; /* File header */
215 static struct aouthdr f_ohdr
; /* Optional file header (a.out) */
216 long bias
; /* Bias to add for growth */
217 long lnnoptr
; /* Pointer to line-number info within file */
219 static long text_scnptr
;
220 static long data_scnptr
;
222 #define ALIGN(val, pwr) (((val) + ((1L<<(pwr))-1)) & ~((1L<<(pwr))-1))
223 static long load_scnptr
;
224 static long orig_load_scnptr
;
225 static long orig_data_scnptr
;
227 static ulong data_st
; /* start of data area written out */
230 #define MAX_SECTIONS 10
237 /* Correct an int which is the bit pattern of a pointer to a byte
238 into an int which is the number of a byte.
239 This is a no-op on ordinary machines, but not on all. */
241 #ifndef ADDR_CORRECT /* Let m-*.h files override this definition */
242 #define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
249 report_error (file
, fd
)
255 report_file_error ("Cannot unexec", Fcons (build_string (file
), Qnil
));
259 #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
260 #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
261 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
264 report_error_1 (fd
, msg
, a1
, a2
)
273 fprintf (stderr
, msg
, a1
, a2
);
274 fprintf (stderr
, "\n");
278 static int make_hdr ();
279 static void mark_x ();
280 static int copy_text_and_data ();
281 static int copy_sym ();
283 /* ****************************************************************
288 unexec (new_name
, a_name
, data_start
, bss_start
, entry_address
)
289 char *new_name
, *a_name
;
290 unsigned data_start
, bss_start
, entry_address
;
294 if (a_name
&& (a_out
= open (a_name
, 0)) < 0)
298 if ((new = creat (new_name
, 0666)) < 0)
302 if (make_hdr (new,a_out
,data_start
,bss_start
,entry_address
,a_name
,new_name
) < 0
303 || copy_text_and_data (new) < 0
304 || copy_sym (new, a_out
, a_name
, new_name
) < 0
306 || adjust_lnnoptrs (new, a_out
, new_name
) < 0
309 || unrelocate_symbols (new, a_out
, a_name
, new_name
) < 0
324 /* ****************************************************************
327 * Make the header in the new a.out from the header in core.
328 * Modify the text and data sizes.
331 make_hdr (new, a_out
, data_start
, bss_start
, entry_address
, a_name
, new_name
)
333 unsigned data_start
, bss_start
, entry_address
;
338 unsigned int bss_end
;
340 struct scnhdr section
[MAX_SECTIONS
];
341 struct scnhdr
* f_thdr
; /* Text section header */
342 struct scnhdr
* f_dhdr
; /* Data section header */
343 struct scnhdr
* f_bhdr
; /* Bss section header */
344 struct scnhdr
* f_lhdr
; /* Loader section header */
345 struct scnhdr
* f_tchdr
; /* Typechk section header */
346 struct scnhdr
* f_dbhdr
; /* Debug section header */
347 struct scnhdr
* f_xhdr
; /* Except section header */
349 load_scnptr
= orig_load_scnptr
= lnnoptr
= 0;
350 pagemask
= getpagesize () - 1;
352 /* Adjust text/data boundary. */
354 data_start
= (long) start_of_data ();
355 #endif /* NO_REMAP */
356 data_start
= ADDR_CORRECT (data_start
);
359 data_start
= data_start
& ~SEGMENT_MASK
; /* (Down) to segment boundary. */
361 data_start
= data_start
& ~pagemask
; /* (Down) to page boundary. */
365 bss_end
= ADDR_CORRECT (sbrk (0)) + pagemask
;
366 bss_end
&= ~ pagemask
;
367 /* Adjust data/bss boundary. */
370 bss_start
= (ADDR_CORRECT (bss_start
) + pagemask
);
371 /* (Up) to page bdry. */
372 bss_start
&= ~ pagemask
;
373 if (bss_start
> bss_end
)
375 ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
382 if (data_start
> bss_start
) /* Can't have negative data size. */
384 ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
385 data_start
, bss_start
);
389 /* Salvage as much info from the existing file as possible */
390 f_thdr
= NULL
; f_dhdr
= NULL
; f_bhdr
= NULL
;
391 f_lhdr
= NULL
; f_tchdr
= NULL
; f_dbhdr
= NULL
; f_xhdr
= NULL
;
394 if (read (a_out
, &f_hdr
, sizeof (f_hdr
)) != sizeof (f_hdr
))
398 if (f_hdr
.f_opthdr
> 0)
400 if (read (a_out
, &f_ohdr
, sizeof (f_ohdr
)) != sizeof (f_ohdr
))
405 if (f_hdr
.f_nscns
> MAX_SECTIONS
)
407 ERROR0 ("unexec: too many section headers -- increase MAX_SECTIONS");
409 /* Loop through section headers */
410 for (scns
= 0; scns
< f_hdr
.f_nscns
; scns
++) {
411 struct scnhdr
*s
= §ion
[scns
];
412 if (read (a_out
, s
, sizeof (*s
)) != sizeof (*s
))
417 #define CHECK_SCNHDR(ptr, name, flags) \
418 if (strcmp(s->s_name, name) == 0) { \
419 if (s->s_flags != flags) { \
420 fprintf(stderr, "unexec: %lx flags where %x expected in %s section.\n", \
421 (unsigned long)s->s_flags, flags, name); \
424 fprintf(stderr, "unexec: duplicate section header for section %s.\n", \
429 CHECK_SCNHDR(f_thdr
, _TEXT
, STYP_TEXT
);
430 CHECK_SCNHDR(f_dhdr
, _DATA
, STYP_DATA
);
431 CHECK_SCNHDR(f_bhdr
, _BSS
, STYP_BSS
);
432 CHECK_SCNHDR(f_lhdr
, _LOADER
, STYP_LOADER
);
433 CHECK_SCNHDR(f_dbhdr
, _DEBUG
, STYP_DEBUG
);
434 CHECK_SCNHDR(f_tchdr
, _TYPCHK
, STYP_TYPCHK
);
435 CHECK_SCNHDR(f_xhdr
, _EXCEPT
, STYP_EXCEPT
);
440 ERROR1 ("unexec: couldn't find \"%s\" section", _TEXT
);
444 ERROR1 ("unexec: couldn't find \"%s\" section", _DATA
);
448 ERROR1 ("unexec: couldn't find \"%s\" section", _BSS
);
453 ERROR0 ("can't build a COFF file from scratch yet");
455 orig_data_scnptr
= f_dhdr
->s_scnptr
;
456 orig_load_scnptr
= f_lhdr
? f_lhdr
->s_scnptr
: 0;
458 /* Now we alter the contents of all the f_*hdr variables
459 to correspond to what we want to dump. */
461 /* Indicate that the reloc information is no longer valid for ld (bind);
462 we only update it enough to fake out the exec-time loader. */
463 f_hdr
.f_flags
|= (F_RELFLG
| F_EXEC
);
466 f_ohdr
.magic
= EXEC_MAGIC
;
469 f_ohdr
.tsize
= data_start
- f_ohdr
.text_start
;
470 f_ohdr
.text_start
= (long) start_of_text ();
472 data_st
= f_ohdr
.data_start
? f_ohdr
.data_start
: (ulong
) &_data
;
473 f_ohdr
.dsize
= bss_start
- data_st
;
474 f_ohdr
.bsize
= bss_end
- bss_start
;
476 f_dhdr
->s_size
= f_ohdr
.dsize
;
477 f_bhdr
->s_size
= f_ohdr
.bsize
;
478 f_bhdr
->s_paddr
= f_ohdr
.data_start
+ f_ohdr
.dsize
;
479 f_bhdr
->s_vaddr
= f_ohdr
.data_start
+ f_ohdr
.dsize
;
483 ulong ptr
= section
[0].s_scnptr
;
486 for (scns
= 0; scns
< f_hdr
.f_nscns
; scns
++)
488 struct scnhdr
*s
= §ion
[scns
];
490 if (s
->s_flags
& STYP_PAD
) /* .pad sections omitted in AIX 4.1 */
493 * the text_start should probably be o_algntext but that doesn't
496 if (f_ohdr
.text_start
!= 0) /* && scns != 0 */
498 s
->s_size
= 512 - (ptr
% 512);
499 if (s
->s_size
== 512)
504 else if (s
->s_flags
& STYP_DATA
)
506 else if (!(s
->s_flags
& (STYP_TEXT
| STYP_BSS
)))
508 if (bias
== -1) /* if first section after bss */
509 bias
= ptr
- s
->s_scnptr
;
515 ptr
= ptr
+ s
->s_size
;
519 /* fix other pointers */
520 for (scns
= 0; scns
< f_hdr
.f_nscns
; scns
++)
522 struct scnhdr
*s
= §ion
[scns
];
524 if (s
->s_relptr
!= 0)
528 if (s
->s_lnnoptr
!= 0)
530 if (lnnoptr
== 0) lnnoptr
= s
->s_lnnoptr
;
531 s
->s_lnnoptr
+= bias
;
535 if (f_hdr
.f_symptr
> 0L)
537 f_hdr
.f_symptr
+= bias
;
540 text_scnptr
= f_thdr
->s_scnptr
;
541 data_scnptr
= f_dhdr
->s_scnptr
;
542 load_scnptr
= f_lhdr
? f_lhdr
->s_scnptr
: 0;
544 #ifdef ADJUST_EXEC_HEADER
546 #endif /* ADJUST_EXEC_HEADER */
548 if (write (new, &f_hdr
, sizeof (f_hdr
)) != sizeof (f_hdr
))
553 if (f_hdr
.f_opthdr
> 0)
555 if (write (new, &f_ohdr
, sizeof (f_ohdr
)) != sizeof (f_ohdr
))
561 for (scns
= 0; scns
< f_hdr
.f_nscns
; scns
++) {
562 struct scnhdr
*s
= §ion
[scns
];
563 if (write (new, s
, sizeof (*s
)) != sizeof (*s
))
574 /* ****************************************************************
577 * Copy the text and data segments from memory to the new a.out
580 copy_text_and_data (new)
586 lseek (new, (long) text_scnptr
, 0);
587 ptr
= start_of_text () + text_scnptr
;
588 end
= ptr
+ f_ohdr
.tsize
;
589 write_segment (new, ptr
, end
);
591 lseek (new, (long) data_scnptr
, 0);
592 ptr
= (char *) data_st
;
593 end
= ptr
+ f_ohdr
.dsize
;
594 write_segment (new, ptr
, end
);
599 #define UnexBlockSz (1<<12) /* read/write block size */
600 write_segment (new, ptr
, end
)
602 register char *ptr
, *end
;
604 register int i
, nwrite
, ret
;
607 char zeros
[UnexBlockSz
];
609 for (i
= 0; ptr
< end
;)
611 /* distance to next block. */
612 nwrite
= (((int) ptr
+ UnexBlockSz
) & -UnexBlockSz
) - (int) ptr
;
613 /* But not beyond specified end. */
614 if (nwrite
> end
- ptr
) nwrite
= end
- ptr
;
615 ret
= write (new, ptr
, nwrite
);
616 /* If write gets a page fault, it means we reached
617 a gap between the old text segment and the old data segment.
618 This gap has probably been remapped into part of the text segment.
619 So write zeros for it. */
620 if (ret
== -1 && errno
== EFAULT
)
622 bzero (zeros
, nwrite
);
623 write (new, zeros
, nwrite
);
625 else if (nwrite
!= ret
)
628 "unexec write failure: addr 0x%lx, fileno %d, size 0x%x, wrote 0x%x, errno %d",
629 (unsigned long)ptr
, new, nwrite
, ret
, errno
);
637 /* ****************************************************************
640 * Copy the relocation information and symbol table from the a.out to the new
643 copy_sym (new, a_out
, a_name
, new_name
)
645 char *a_name
, *new_name
;
647 char page
[UnexBlockSz
];
653 if (orig_load_scnptr
== 0L)
656 if (lnnoptr
&& lnnoptr
< orig_load_scnptr
) /* if there is line number info */
657 lseek (a_out
, lnnoptr
, 0); /* start copying from there */
659 lseek (a_out
, orig_load_scnptr
, 0); /* Position a.out to symtab. */
661 while ((n
= read (a_out
, page
, sizeof page
)) > 0)
663 if (write (new, page
, n
) != n
)
675 /* ****************************************************************
678 * After successfully building the new a.out, mark it executable
686 int new = 0; /* for PERROR */
690 if (stat (name
, &sbuf
) == -1)
694 sbuf
.st_mode
|= 0111 & ~um
;
695 if (chmod (name
, sbuf
.st_mode
) == -1)
700 * If the COFF file contains a symbol table and a line number section,
701 * then any auxiliary entries that have values for x_lnnoptr must
702 * be adjusted by the amount that the line number section has moved
703 * in the file (bias computed in make_hdr). The #@$%&* designers of
704 * the auxiliary entry structures used the absolute file offsets for
705 * the line number entry rather than an offset from the start of the
706 * line number section!
708 * When I figure out how to scan through the symbol table and pick out
709 * the auxiliary entries that need adjustment, this routine will
710 * be fixed. As it is now, all such entries are wrong and sdb
711 * will complain. Fred Fish, UniSoft Systems Inc.
713 * I believe this is now fixed correctly. Bill Mann
718 /* This function is probably very slow. Instead of reopening the new
719 file for input and output it should copy from the old to the new
720 using the two descriptors already open (WRITEDESC and READDESC).
721 Instead of reading one small structure at a time it should use
722 a reasonable size buffer. But I don't have time to work on such
723 things, so I am installing it as submitted to me. -- RMS. */
725 adjust_lnnoptrs (writedesc
, readdesc
, new_name
)
737 struct syment symentry
;
738 union auxent auxentry
;
741 if (!lnnoptr
|| !f_hdr
.f_symptr
)
744 if ((new = open (new_name
, 2)) < 0)
750 lseek (new, f_hdr
.f_symptr
, 0);
751 for (nsyms
= 0; nsyms
< f_hdr
.f_nsyms
; nsyms
++)
753 read (new, &symentry
, SYMESZ
);
754 if (symentry
.n_sclass
== C_BINCL
|| symentry
.n_sclass
== C_EINCL
)
756 symentry
.n_value
+= bias
;
757 lseek (new, -SYMESZ
, 1);
758 write (new, &symentry
, SYMESZ
);
761 for (naux
= symentry
.n_numaux
; naux
-- != 0; )
763 read (new, &auxentry
, AUXESZ
);
765 if (naux
!= 0 /* skip csect auxentry (last entry) */
766 && (symentry
.n_sclass
== C_EXT
|| symentry
.n_sclass
== C_HIDEXT
))
768 auxentry
.x_sym
.x_fcnary
.x_fcn
.x_lnnoptr
+= bias
;
769 lseek (new, -AUXESZ
, 1);
770 write (new, &auxentry
, AUXESZ
);
781 /* It is probably a false economy to optimise this routine (it used to
782 read one LDREL and do do two lseeks per iteration) but the wrath of
783 RMS (see above :-) would be too much to bear */
785 unrelocate_symbols (new, a_out
, a_name
, new_name
)
787 char *a_name
, *new_name
;
791 register LDREL
*ldrel
;
793 LDREL ldrel_buf
[20];
794 ulong t_reloc
= (ulong
) &_text
- f_ohdr
.text_start
;
795 ulong d_reloc
= (ulong
) &_data
- ALIGN(f_ohdr
.data_start
, 2);
798 if (load_scnptr
== 0)
801 lseek (a_out
, orig_load_scnptr
, 0);
802 if (read (a_out
, &ldhdr
, sizeof (ldhdr
)) != sizeof (ldhdr
))
807 #define SYMNDX_TEXT 0
808 #define SYMNDX_DATA 1
811 for (i
= 0; i
< ldhdr
.l_nreloc
; i
++, l
--, ldrel
++)
815 orig_load_scnptr
+ LDHDRSZ
+ LDSYMSZ
*ldhdr
.l_nsyms
+ LDRELSZ
*i
,
818 l
= ldhdr
.l_nreloc
- i
;
819 if (l
> sizeof (ldrel_buf
) / LDRELSZ
)
820 l
= sizeof (ldrel_buf
) / LDRELSZ
;
822 if (read (a_out
, ldrel_buf
, l
* LDRELSZ
) != l
* LDRELSZ
)
829 /* move the BSS loader symbols to the DATA segment */
830 if (ldrel
->l_symndx
== SYMNDX_BSS
)
832 ldrel
->l_symndx
= SYMNDX_DATA
;
835 load_scnptr
+ LDHDRSZ
+ LDSYMSZ
*ldhdr
.l_nsyms
+ LDRELSZ
*i
,
838 if (write (new, ldrel
, LDRELSZ
) != LDRELSZ
)
844 if (ldrel
->l_rsecnm
== f_ohdr
.o_sndata
)
849 orig_data_scnptr
+ (ldrel
->l_vaddr
- f_ohdr
.data_start
), 0);
851 if (read (a_out
, (void *) &orig_int
, sizeof (orig_int
)) != sizeof (orig_int
))
856 p
= (int *) (ldrel
->l_vaddr
+ d_reloc
);
858 switch (ldrel
->l_symndx
) {
860 orig_int
= * p
- t_reloc
;
865 orig_int
= * p
- d_reloc
;
872 data_scnptr
+ (ldrel
->l_vaddr
- f_ohdr
.data_start
), 0);
873 if (write (new, (void *) &orig_int
, sizeof (orig_int
))
874 != sizeof (orig_int
))