1 /* Copyright (C) 1985, 1986, 1987, 1988, 1992, 1993, 1994, 2001, 2002, 2003,
2 2004, 2005, 2006, 2007, 2008 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 3 of the License, or
9 (at your option) 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. If not, see <http://www.gnu.org/licenses/>. */
21 * unexec.c - Convert a running program into an a.out file.
23 * Author: Spencer W. Thomas
24 * Computer Science Dept.
26 * Date: Tue Mar 2 1982
27 * Modified heavily since then.
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;
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.
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.
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.
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.
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
61 * The new file is set up to start at entry_address.
63 * If you make improvements I'd like to get them too.
64 * harpo!utah-cs!thomas, thomas@Utah-20
68 /* Modified to support SysVr3 shared libraries by James Van Artsdalen
69 * of Dell Computer Corporation. james@bigtex.cactus.org.
72 /* There are several compilation parameters affecting unexec:
76 Define this if your system uses COFF for executables.
80 Define this if you do not want to try to save Emacs's pure data areas
81 as part of the text segment.
83 Saving them as text is good because it allows users to share more.
85 However, on machines that locate the text area far from the data area,
86 the boundary cannot feasibly be moved. Such machines require
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.
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.
103 If SECTION_ALIGNMENT is not defined, the segments are written
104 consecutively with no attempt at alignment. This is right for
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.
117 This macro can be used to generate statements to adjust or
118 initialize nonstandard fields in the file header
122 Macro to correct an int which is the bit pattern of a pointer to a byte
123 into an int which is the number of a byte.
125 This macro has a default definition which is usually right.
126 This default definition is a no-op on most machines (where a
127 pointer looks like an int) but not on all machines.
132 #define PERROR(arg) perror (arg); return -1
135 #define PERROR(file) report_error (file, new)
138 #ifndef CANNOT_DUMP /* all rest of file! */
144 #include <fcntl.h> /* for O_RDONLY, O_RDWR */
145 #include <crt0.h> /* for _crt0_startup_flags and its bits */
146 static int save_djgpp_startup_flags
;
147 #endif /* __DJGPP__ > 1 */
148 #define filehdr external_filehdr
149 #define scnhdr external_scnhdr
150 #define syment external_syment
151 #define auxent external_auxent
152 #define n_numaux e_numaux
153 #define n_type e_type
156 unsigned short magic
; /* type of file */
157 unsigned short vstamp
; /* version stamp */
158 unsigned long tsize
; /* text size in bytes, padded to FW bdry*/
159 unsigned long dsize
; /* initialized data " " */
160 unsigned long bsize
; /* uninitialized data " " */
161 unsigned long entry
; /* entry pt. */
162 unsigned long text_start
;/* base of text used for this file */
163 unsigned long data_start
;/* base of data used for this file */
165 #endif /* not MSDOS */
166 #else /* not HAVE_COFF_H */
168 #endif /* not HAVE_COFF_H */
170 /* Define getpagesize if the system does not.
171 Note that this may depend on symbols defined in a.out.h. */
172 #include "getpagesize.h"
174 #ifndef makedev /* Try to detect types.h already loaded */
175 #include <sys/types.h>
178 #include <sys/stat.h>
181 #include <sys/file.h>
191 extern char *start_of_text (); /* Start of text */
192 extern char *start_of_data (); /* Start of initialized data */
194 static long block_copy_start
; /* Old executable start point */
195 static struct filehdr f_hdr
; /* File header */
196 static struct aouthdr f_ohdr
; /* Optional file header (a.out) */
197 long bias
; /* Bias to add for growth */
198 long lnnoptr
; /* Pointer to line-number info within file */
199 #define SYMS_START block_copy_start
201 static long text_scnptr
;
202 static long data_scnptr
;
204 static long coff_offset
;
208 /* Correct an int which is the bit pattern of a pointer to a byte
209 into an int which is the number of a byte.
210 This is a no-op on ordinary machines, but not on all. */
212 #ifndef ADDR_CORRECT /* Let m-*.h files override this definition */
213 #define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
221 report_error (file
, fd
)
227 report_file_error ("Cannot unexec", Fcons (build_string (file
), Qnil
));
231 #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
232 #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
233 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
236 report_error_1 (fd
, msg
, a1
, a2
)
245 fprintf (stderr
, msg
, a1
, a2
);
246 fprintf (stderr
, "\n");
250 static int make_hdr ();
251 static int copy_text_and_data ();
252 static int copy_sym ();
253 static void mark_x ();
255 /* ****************************************************************
258 * Make the header in the new a.out from the header in core.
259 * Modify the text and data sizes.
262 make_hdr (new, a_out
, data_start
, bss_start
, entry_address
, a_name
, new_name
)
264 unsigned data_start
, bss_start
, entry_address
;
269 auto struct scnhdr f_thdr
; /* Text section header */
270 auto struct scnhdr f_dhdr
; /* Data section header */
271 auto struct scnhdr f_bhdr
; /* Bss section header */
272 auto struct scnhdr scntemp
; /* Temporary section header */
274 unsigned int bss_end
;
276 pagemask
= getpagesize () - 1;
278 /* Adjust text/data boundary. */
280 data_start
= (int) start_of_data ();
281 #else /* not NO_REMAP */
283 data_start
= (int) start_of_data ();
284 #endif /* not NO_REMAP */
285 data_start
= ADDR_CORRECT (data_start
);
288 data_start
= data_start
& ~SEGMENT_MASK
; /* (Down) to segment boundary. */
290 data_start
= data_start
& ~pagemask
; /* (Down) to page boundary. */
293 bss_end
= ADDR_CORRECT (sbrk (0)) + pagemask
;
294 bss_end
&= ~ pagemask
;
296 /* Adjust data/bss boundary. */
299 bss_start
= (ADDR_CORRECT (bss_start
) + pagemask
);
300 /* (Up) to page bdry. */
301 bss_start
&= ~ pagemask
;
302 if (bss_start
> bss_end
)
304 ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
311 if (data_start
> bss_start
) /* Can't have negative data size. */
313 ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
314 data_start
, bss_start
);
317 coff_offset
= 0L; /* stays zero, except in DJGPP */
319 /* Salvage as much info from the existing file as possible */
324 /* Support the coff-go32-exe format with a prepended stub, since
325 this is what GCC 2.8.0 and later generates by default in DJGPP. */
326 unsigned short mz_header
[3];
328 if (read (a_out
, &mz_header
, sizeof (mz_header
)) != sizeof (mz_header
))
332 if (mz_header
[0] == 0x5a4d || mz_header
[0] == 0x4d5a) /* "MZ" or "ZM" */
334 coff_offset
= (long)mz_header
[2] * 512L;
336 coff_offset
+= (long)mz_header
[1] - 512L;
337 lseek (a_out
, coff_offset
, 0);
340 lseek (a_out
, 0L, 0);
341 #endif /* __DJGPP__ > 1 */
343 if (read (a_out
, &f_hdr
, sizeof (f_hdr
)) != sizeof (f_hdr
))
347 block_copy_start
+= sizeof (f_hdr
);
348 if (f_hdr
.f_opthdr
> 0)
350 if (read (a_out
, &f_ohdr
, sizeof (f_ohdr
)) != sizeof (f_ohdr
))
354 block_copy_start
+= sizeof (f_ohdr
);
356 /* Loop through section headers, copying them in */
357 lseek (a_out
, coff_offset
+ sizeof (f_hdr
) + f_hdr
.f_opthdr
, 0);
358 for (scns
= f_hdr
.f_nscns
; scns
> 0; scns
--) {
359 if (read (a_out
, &scntemp
, sizeof (scntemp
)) != sizeof (scntemp
))
363 if (scntemp
.s_scnptr
> 0L)
365 if (block_copy_start
< scntemp
.s_scnptr
+ scntemp
.s_size
)
366 block_copy_start
= scntemp
.s_scnptr
+ scntemp
.s_size
;
368 if (strcmp (scntemp
.s_name
, ".text") == 0)
372 else if (strcmp (scntemp
.s_name
, ".data") == 0)
376 else if (strcmp (scntemp
.s_name
, ".bss") == 0)
384 ERROR0 ("can't build a COFF file from scratch yet");
387 /* Now we alter the contents of all the f_*hdr variables
388 to correspond to what we want to dump. */
390 f_hdr
.f_flags
|= (F_RELFLG
| F_EXEC
);
392 f_ohdr
.text_start
= (long) start_of_text ();
393 f_ohdr
.tsize
= data_start
- f_ohdr
.text_start
;
394 f_ohdr
.data_start
= data_start
;
395 #endif /* NO_REMAP */
396 f_ohdr
.dsize
= bss_start
- f_ohdr
.data_start
;
397 f_ohdr
.bsize
= bss_end
- bss_start
;
398 /* On some machines, the old values are right.
399 ??? Maybe on all machines with NO_REMAP. */
400 f_thdr
.s_size
= f_ohdr
.tsize
;
401 f_thdr
.s_scnptr
= sizeof (f_hdr
) + sizeof (f_ohdr
);
402 f_thdr
.s_scnptr
+= (f_hdr
.f_nscns
) * (sizeof (f_thdr
));
403 lnnoptr
= f_thdr
.s_lnnoptr
;
404 #ifdef SECTION_ALIGNMENT
405 /* Some systems require special alignment
406 of the sections in the file itself. */
408 = (f_thdr
.s_scnptr
+ SECTION_ALIGNMENT
) & ~SECTION_ALIGNMENT
;
409 #endif /* SECTION_ALIGNMENT */
410 text_scnptr
= f_thdr
.s_scnptr
;
411 f_dhdr
.s_paddr
= f_ohdr
.data_start
;
412 f_dhdr
.s_vaddr
= f_ohdr
.data_start
;
413 f_dhdr
.s_size
= f_ohdr
.dsize
;
414 f_dhdr
.s_scnptr
= f_thdr
.s_scnptr
+ f_thdr
.s_size
;
415 #ifdef SECTION_ALIGNMENT
416 /* Some systems require special alignment
417 of the sections in the file itself. */
419 = (f_dhdr
.s_scnptr
+ SECTION_ALIGNMENT
) & ~SECTION_ALIGNMENT
;
420 #endif /* SECTION_ALIGNMENT */
421 #ifdef DATA_SECTION_ALIGNMENT
422 /* Some systems require special alignment
423 of the data section only. */
425 = (f_dhdr
.s_scnptr
+ DATA_SECTION_ALIGNMENT
) & ~DATA_SECTION_ALIGNMENT
;
426 #endif /* DATA_SECTION_ALIGNMENT */
427 data_scnptr
= f_dhdr
.s_scnptr
;
428 f_bhdr
.s_paddr
= f_ohdr
.data_start
+ f_ohdr
.dsize
;
429 f_bhdr
.s_vaddr
= f_ohdr
.data_start
+ f_ohdr
.dsize
;
430 f_bhdr
.s_size
= f_ohdr
.bsize
;
431 f_bhdr
.s_scnptr
= 0L;
432 bias
= f_dhdr
.s_scnptr
+ f_dhdr
.s_size
- block_copy_start
;
434 if (f_hdr
.f_symptr
> 0L)
436 f_hdr
.f_symptr
+= bias
;
439 if (f_thdr
.s_lnnoptr
> 0L)
441 f_thdr
.s_lnnoptr
+= bias
;
444 #ifdef ADJUST_EXEC_HEADER
446 #endif /* ADJUST_EXEC_HEADER */
448 if (write (new, &f_hdr
, sizeof (f_hdr
)) != sizeof (f_hdr
))
453 if (write (new, &f_ohdr
, sizeof (f_ohdr
)) != sizeof (f_ohdr
))
458 if (write (new, &f_thdr
, sizeof (f_thdr
)) != sizeof (f_thdr
))
463 if (write (new, &f_dhdr
, sizeof (f_dhdr
)) != sizeof (f_dhdr
))
468 if (write (new, &f_bhdr
, sizeof (f_bhdr
)) != sizeof (f_bhdr
))
477 write_segment (new, ptr
, end
)
479 register char *ptr
, *end
;
481 register int i
, nwrite
, ret
;
486 /* This is the normal amount to write at once.
487 It is the size of block that NFS uses. */
488 int writesize
= 1 << 13;
489 int pagesize
= getpagesize ();
492 bzero (zeros
, sizeof (zeros
));
494 for (i
= 0; ptr
< end
;)
496 /* Distance to next multiple of writesize. */
497 nwrite
= (((int) ptr
+ writesize
) & -writesize
) - (int) ptr
;
498 /* But not beyond specified end. */
499 if (nwrite
> end
- ptr
) nwrite
= end
- ptr
;
500 ret
= write (new, ptr
, nwrite
);
501 /* If write gets a page fault, it means we reached
502 a gap between the old text segment and the old data segment.
503 This gap has probably been remapped into part of the text segment.
504 So write zeros for it. */
511 /* Write only a page of zeros at once,
512 so that we we don't overshoot the start
513 of the valid memory in the old data segment. */
514 if (nwrite
> pagesize
)
516 write (new, zeros
, nwrite
);
518 #if 0 /* Now that we have can ask `write' to write more than a page,
519 it is legit for write do less than the whole amount specified. */
520 else if (nwrite
!= ret
)
523 "unexec write failure: addr 0x%x, fileno %d, size 0x%x, wrote 0x%x, errno %d",
524 ptr
, new, nwrite
, ret
, errno
);
532 /* ****************************************************************
535 * Copy the text and data segments from memory to the new a.out
538 copy_text_and_data (new, a_out
)
546 /* Dump the original table of exception handlers, not the one
547 where our exception hooks are registered. */
548 __djgpp_exception_toggle ();
550 /* Switch off startup flags that might have been set at runtime
551 and which might change the way that dumped Emacs works. */
552 save_djgpp_startup_flags
= _crt0_startup_flags
;
553 _crt0_startup_flags
&= ~(_CRT0_FLAG_NO_LFN
| _CRT0_FLAG_NEARPTR
);
557 lseek (new, (long) text_scnptr
, 0);
558 ptr
= (char *) f_ohdr
.text_start
;
559 end
= ptr
+ f_ohdr
.tsize
;
560 write_segment (new, ptr
, end
);
562 lseek (new, (long) data_scnptr
, 0);
563 ptr
= (char *) f_ohdr
.data_start
;
564 end
= ptr
+ f_ohdr
.dsize
;
565 write_segment (new, ptr
, end
);
569 /* Restore our exception hooks. */
570 __djgpp_exception_toggle ();
572 /* Restore the startup flags. */
573 _crt0_startup_flags
= save_djgpp_startup_flags
;
581 /* ****************************************************************
584 * Copy the relocation information and symbol table from the a.out to the new
587 copy_sym (new, a_out
, a_name
, new_name
)
589 char *a_name
, *new_name
;
597 if (SYMS_START
== 0L)
600 if (lnnoptr
) /* if there is line number info */
601 lseek (a_out
, coff_offset
+ lnnoptr
, 0); /* start copying from there */
603 lseek (a_out
, coff_offset
+ SYMS_START
, 0); /* Position a.out to symtab. */
605 while ((n
= read (a_out
, page
, sizeof page
)) > 0)
607 if (write (new, page
, n
) != n
)
619 /* ****************************************************************
622 * After successfully building the new a.out, mark it executable
630 int new = 0; /* for PERROR */
634 if (stat (name
, &sbuf
) == -1)
638 sbuf
.st_mode
|= 0111 & ~um
;
639 if (chmod (name
, sbuf
.st_mode
) == -1)
643 #ifndef COFF_BSD_SYMBOLS
646 * If the COFF file contains a symbol table and a line number section,
647 * then any auxiliary entries that have values for x_lnnoptr must
648 * be adjusted by the amount that the line number section has moved
649 * in the file (bias computed in make_hdr). The #@$%&* designers of
650 * the auxiliary entry structures used the absolute file offsets for
651 * the line number entry rather than an offset from the start of the
652 * line number section!
654 * When I figure out how to scan through the symbol table and pick out
655 * the auxiliary entries that need adjustment, this routine will
656 * be fixed. As it is now, all such entries are wrong and sdb
657 * will complain. Fred Fish, UniSoft Systems Inc.
660 /* This function is probably very slow. Instead of reopening the new
661 file for input and output it should copy from the old to the new
662 using the two descriptors already open (WRITEDESC and READDESC).
663 Instead of reading one small structure at a time it should use
664 a reasonable size buffer. But I don't have time to work on such
665 things, so I am installing it as submitted to me. -- RMS. */
667 adjust_lnnoptrs (writedesc
, readdesc
, new_name
)
674 struct syment symentry
;
675 union auxent auxentry
;
677 if (!lnnoptr
|| !f_hdr
.f_symptr
)
681 if ((new = writedesc
) < 0)
683 if ((new = open (new_name
, O_RDWR
)) < 0)
690 lseek (new, f_hdr
.f_symptr
, 0);
691 for (nsyms
= 0; nsyms
< f_hdr
.f_nsyms
; nsyms
++)
693 read (new, &symentry
, SYMESZ
);
694 if (symentry
.n_numaux
)
696 read (new, &auxentry
, AUXESZ
);
698 if (ISFCN (symentry
.n_type
) || symentry
.n_type
== 0x2400)
700 auxentry
.x_sym
.x_fcnary
.x_fcn
.x_lnnoptr
+= bias
;
701 lseek (new, -AUXESZ
, 1);
702 write (new, &auxentry
, AUXESZ
);
712 #endif /* COFF_BSD_SYMBOLS */
714 /* ****************************************************************
719 unexec (new_name
, a_name
, data_start
, bss_start
, entry_address
)
720 char *new_name
, *a_name
;
721 unsigned data_start
, bss_start
, entry_address
;
725 if (a_name
&& (a_out
= open (a_name
, O_RDONLY
)) < 0)
729 if ((new = creat (new_name
, 0666)) < 0)
734 if (make_hdr (new, a_out
, data_start
, bss_start
, entry_address
, a_name
, new_name
) < 0
735 || copy_text_and_data (new, a_out
) < 0
736 || copy_sym (new, a_out
, a_name
, new_name
) < 0
737 #ifndef COFF_BSD_SYMBOLS
738 || adjust_lnnoptrs (new, a_out
, new_name
) < 0
743 /* unlink (new_name); /* Failed, unlink new a.out */
754 #endif /* not CANNOT_DUMP */
756 /* arch-tag: 62409b69-e27a-4a7c-9413-0210d6b54e7f
757 (do not change this comment) */