1 /* Copyright (C) 1985, 1986, 1987, 1988, 1992, 1993, 1994, 2001, 2002, 2003,
2 2004, 2005, 2006, 2007, 2008, 2009, 2010 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
123 #define PERROR(arg) perror (arg); return -1
126 #define PERROR(file) report_error (file, new)
129 #ifndef CANNOT_DUMP /* all rest of file! */
134 #include <fcntl.h> /* for O_RDONLY, O_RDWR */
135 #include <crt0.h> /* for _crt0_startup_flags and its bits */
136 static int save_djgpp_startup_flags
;
137 #define filehdr external_filehdr
138 #define scnhdr external_scnhdr
139 #define syment external_syment
140 #define auxent external_auxent
141 #define n_numaux e_numaux
142 #define n_type e_type
145 unsigned short magic
; /* type of file */
146 unsigned short vstamp
; /* version stamp */
147 unsigned long tsize
; /* text size in bytes, padded to FW bdry*/
148 unsigned long dsize
; /* initialized data " " */
149 unsigned long bsize
; /* uninitialized data " " */
150 unsigned long entry
; /* entry pt. */
151 unsigned long text_start
;/* base of text used for this file */
152 unsigned long data_start
;/* base of data used for this file */
154 #endif /* not MSDOS */
155 #else /* not HAVE_COFF_H */
157 #endif /* not HAVE_COFF_H */
159 /* Define getpagesize if the system does not.
160 Note that this may depend on symbols defined in a.out.h. */
161 #include "getpagesize.h"
163 #ifndef makedev /* Try to detect types.h already loaded */
164 #include <sys/types.h>
167 #include <sys/stat.h>
170 #include <sys/file.h>
180 extern char *start_of_text (); /* Start of text */
181 extern char *start_of_data (); /* Start of initialized data */
183 static long block_copy_start
; /* Old executable start point */
184 static struct filehdr f_hdr
; /* File header */
185 static struct aouthdr f_ohdr
; /* Optional file header (a.out) */
186 long bias
; /* Bias to add for growth */
187 long lnnoptr
; /* Pointer to line-number info within file */
188 #define SYMS_START block_copy_start
190 static long text_scnptr
;
191 static long data_scnptr
;
193 static long coff_offset
;
197 /* Correct an int which is the bit pattern of a pointer to a byte
198 into an int which is the number of a byte.
199 This is a no-op on ordinary machines, but not on all. */
201 #define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
209 report_error (file
, fd
)
215 report_file_error ("Cannot unexec", Fcons (build_string (file
), Qnil
));
219 #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
220 #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
221 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
224 report_error_1 (fd
, msg
, a1
, a2
)
233 fprintf (stderr
, msg
, a1
, a2
);
234 fprintf (stderr
, "\n");
238 static int make_hdr ();
239 static int copy_text_and_data ();
240 static int copy_sym ();
241 static void mark_x ();
243 /* ****************************************************************
246 * Make the header in the new a.out from the header in core.
247 * Modify the text and data sizes.
250 make_hdr (new, a_out
, data_start
, bss_start
, entry_address
, a_name
, new_name
)
252 unsigned data_start
, bss_start
, entry_address
;
257 auto struct scnhdr f_thdr
; /* Text section header */
258 auto struct scnhdr f_dhdr
; /* Data section header */
259 auto struct scnhdr f_bhdr
; /* Bss section header */
260 auto struct scnhdr scntemp
; /* Temporary section header */
262 unsigned int bss_end
;
264 pagemask
= getpagesize () - 1;
266 /* Adjust text/data boundary. */
268 data_start
= (int) start_of_data ();
269 #else /* not NO_REMAP */
271 data_start
= (int) start_of_data ();
272 #endif /* not NO_REMAP */
273 data_start
= ADDR_CORRECT (data_start
);
276 data_start
= data_start
& ~SEGMENT_MASK
; /* (Down) to segment boundary. */
278 data_start
= data_start
& ~pagemask
; /* (Down) to page boundary. */
281 bss_end
= ADDR_CORRECT (sbrk (0)) + pagemask
;
282 bss_end
&= ~ pagemask
;
284 /* Adjust data/bss boundary. */
287 bss_start
= (ADDR_CORRECT (bss_start
) + pagemask
);
288 /* (Up) to page bdry. */
289 bss_start
&= ~ pagemask
;
290 if (bss_start
> bss_end
)
292 ERROR1 ("unexec: Specified bss_start (%u) is past end of program",
299 if (data_start
> bss_start
) /* Can't have negative data size. */
301 ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
302 data_start
, bss_start
);
305 coff_offset
= 0L; /* stays zero, except in DJGPP */
307 /* Salvage as much info from the existing file as possible */
311 /* Support the coff-go32-exe format with a prepended stub, since
312 this is what GCC 2.8.0 and later generates by default in DJGPP. */
313 unsigned short mz_header
[3];
315 if (read (a_out
, &mz_header
, sizeof (mz_header
)) != sizeof (mz_header
))
319 if (mz_header
[0] == 0x5a4d || mz_header
[0] == 0x4d5a) /* "MZ" or "ZM" */
321 coff_offset
= (long)mz_header
[2] * 512L;
323 coff_offset
+= (long)mz_header
[1] - 512L;
324 lseek (a_out
, coff_offset
, 0);
327 lseek (a_out
, 0L, 0);
329 if (read (a_out
, &f_hdr
, sizeof (f_hdr
)) != sizeof (f_hdr
))
333 block_copy_start
+= sizeof (f_hdr
);
334 if (f_hdr
.f_opthdr
> 0)
336 if (read (a_out
, &f_ohdr
, sizeof (f_ohdr
)) != sizeof (f_ohdr
))
340 block_copy_start
+= sizeof (f_ohdr
);
342 /* Loop through section headers, copying them in */
343 lseek (a_out
, coff_offset
+ sizeof (f_hdr
) + f_hdr
.f_opthdr
, 0);
344 for (scns
= f_hdr
.f_nscns
; scns
> 0; scns
--) {
345 if (read (a_out
, &scntemp
, sizeof (scntemp
)) != sizeof (scntemp
))
349 if (scntemp
.s_scnptr
> 0L)
351 if (block_copy_start
< scntemp
.s_scnptr
+ scntemp
.s_size
)
352 block_copy_start
= scntemp
.s_scnptr
+ scntemp
.s_size
;
354 if (strcmp (scntemp
.s_name
, ".text") == 0)
358 else if (strcmp (scntemp
.s_name
, ".data") == 0)
362 else if (strcmp (scntemp
.s_name
, ".bss") == 0)
370 ERROR0 ("can't build a COFF file from scratch yet");
373 /* Now we alter the contents of all the f_*hdr variables
374 to correspond to what we want to dump. */
376 f_hdr
.f_flags
|= (F_RELFLG
| F_EXEC
);
378 f_ohdr
.text_start
= (long) start_of_text ();
379 f_ohdr
.tsize
= data_start
- f_ohdr
.text_start
;
380 f_ohdr
.data_start
= data_start
;
381 #endif /* NO_REMAP */
382 f_ohdr
.dsize
= bss_start
- f_ohdr
.data_start
;
383 f_ohdr
.bsize
= bss_end
- bss_start
;
384 /* On some machines, the old values are right.
385 ??? Maybe on all machines with NO_REMAP. */
386 f_thdr
.s_size
= f_ohdr
.tsize
;
387 f_thdr
.s_scnptr
= sizeof (f_hdr
) + sizeof (f_ohdr
);
388 f_thdr
.s_scnptr
+= (f_hdr
.f_nscns
) * (sizeof (f_thdr
));
389 lnnoptr
= f_thdr
.s_lnnoptr
;
390 #ifdef SECTION_ALIGNMENT
391 /* Some systems require special alignment
392 of the sections in the file itself. */
394 = (f_thdr
.s_scnptr
+ SECTION_ALIGNMENT
) & ~SECTION_ALIGNMENT
;
395 #endif /* SECTION_ALIGNMENT */
396 text_scnptr
= f_thdr
.s_scnptr
;
397 f_dhdr
.s_paddr
= f_ohdr
.data_start
;
398 f_dhdr
.s_vaddr
= f_ohdr
.data_start
;
399 f_dhdr
.s_size
= f_ohdr
.dsize
;
400 f_dhdr
.s_scnptr
= f_thdr
.s_scnptr
+ f_thdr
.s_size
;
401 #ifdef SECTION_ALIGNMENT
402 /* Some systems require special alignment
403 of the sections in the file itself. */
405 = (f_dhdr
.s_scnptr
+ SECTION_ALIGNMENT
) & ~SECTION_ALIGNMENT
;
406 #endif /* SECTION_ALIGNMENT */
407 #ifdef DATA_SECTION_ALIGNMENT
408 /* Some systems require special alignment
409 of the data section only. */
411 = (f_dhdr
.s_scnptr
+ DATA_SECTION_ALIGNMENT
) & ~DATA_SECTION_ALIGNMENT
;
412 #endif /* DATA_SECTION_ALIGNMENT */
413 data_scnptr
= f_dhdr
.s_scnptr
;
414 f_bhdr
.s_paddr
= f_ohdr
.data_start
+ f_ohdr
.dsize
;
415 f_bhdr
.s_vaddr
= f_ohdr
.data_start
+ f_ohdr
.dsize
;
416 f_bhdr
.s_size
= f_ohdr
.bsize
;
417 f_bhdr
.s_scnptr
= 0L;
418 bias
= f_dhdr
.s_scnptr
+ f_dhdr
.s_size
- block_copy_start
;
420 if (f_hdr
.f_symptr
> 0L)
422 f_hdr
.f_symptr
+= bias
;
425 if (f_thdr
.s_lnnoptr
> 0L)
427 f_thdr
.s_lnnoptr
+= bias
;
430 #ifdef ADJUST_EXEC_HEADER
432 #endif /* ADJUST_EXEC_HEADER */
434 if (write (new, &f_hdr
, sizeof (f_hdr
)) != sizeof (f_hdr
))
439 if (write (new, &f_ohdr
, sizeof (f_ohdr
)) != sizeof (f_ohdr
))
444 if (write (new, &f_thdr
, sizeof (f_thdr
)) != sizeof (f_thdr
))
449 if (write (new, &f_dhdr
, sizeof (f_dhdr
)) != sizeof (f_dhdr
))
454 if (write (new, &f_bhdr
, sizeof (f_bhdr
)) != sizeof (f_bhdr
))
463 write_segment (new, ptr
, end
)
465 register char *ptr
, *end
;
467 register int i
, nwrite
, ret
;
469 /* This is the normal amount to write at once.
470 It is the size of block that NFS uses. */
471 int writesize
= 1 << 13;
472 int pagesize
= getpagesize ();
475 memset (zeros
, 0, sizeof (zeros
));
477 for (i
= 0; ptr
< end
;)
479 /* Distance to next multiple of writesize. */
480 nwrite
= (((int) ptr
+ writesize
) & -writesize
) - (int) ptr
;
481 /* But not beyond specified end. */
482 if (nwrite
> end
- ptr
) nwrite
= end
- ptr
;
483 ret
= write (new, ptr
, nwrite
);
484 /* If write gets a page fault, it means we reached
485 a gap between the old text segment and the old data segment.
486 This gap has probably been remapped into part of the text segment.
487 So write zeros for it. */
494 /* Write only a page of zeros at once,
495 so that we don't overshoot the start
496 of the valid memory in the old data segment. */
497 if (nwrite
> pagesize
)
499 write (new, zeros
, nwrite
);
501 #if 0 /* Now that we have can ask `write' to write more than a page,
502 it is legit for write do less than the whole amount specified. */
503 else if (nwrite
!= ret
)
506 "unexec write failure: addr 0x%x, fileno %d, size 0x%x, wrote 0x%x, errno %d",
507 ptr
, new, nwrite
, ret
, errno
);
515 /* ****************************************************************
518 * Copy the text and data segments from memory to the new a.out
521 copy_text_and_data (new, a_out
)
528 /* Dump the original table of exception handlers, not the one
529 where our exception hooks are registered. */
530 __djgpp_exception_toggle ();
532 /* Switch off startup flags that might have been set at runtime
533 and which might change the way that dumped Emacs works. */
534 save_djgpp_startup_flags
= _crt0_startup_flags
;
535 _crt0_startup_flags
&= ~(_CRT0_FLAG_NO_LFN
| _CRT0_FLAG_NEARPTR
);
538 lseek (new, (long) text_scnptr
, 0);
539 ptr
= (char *) f_ohdr
.text_start
;
540 end
= ptr
+ f_ohdr
.tsize
;
541 write_segment (new, ptr
, end
);
543 lseek (new, (long) data_scnptr
, 0);
544 ptr
= (char *) f_ohdr
.data_start
;
545 end
= ptr
+ f_ohdr
.dsize
;
546 write_segment (new, ptr
, end
);
549 /* Restore our exception hooks. */
550 __djgpp_exception_toggle ();
552 /* Restore the startup flags. */
553 _crt0_startup_flags
= save_djgpp_startup_flags
;
560 /* ****************************************************************
563 * Copy the relocation information and symbol table from the a.out to the new
566 copy_sym (new, a_out
, a_name
, new_name
)
568 char *a_name
, *new_name
;
576 if (SYMS_START
== 0L)
579 if (lnnoptr
) /* if there is line number info */
580 lseek (a_out
, coff_offset
+ lnnoptr
, 0); /* start copying from there */
582 lseek (a_out
, coff_offset
+ SYMS_START
, 0); /* Position a.out to symtab. */
584 while ((n
= read (a_out
, page
, sizeof page
)) > 0)
586 if (write (new, page
, n
) != n
)
598 /* ****************************************************************
601 * After successfully building the new a.out, mark it executable
609 int new = 0; /* for PERROR */
613 if (stat (name
, &sbuf
) == -1)
617 sbuf
.st_mode
|= 0111 & ~um
;
618 if (chmod (name
, sbuf
.st_mode
) == -1)
624 * If the COFF file contains a symbol table and a line number section,
625 * then any auxiliary entries that have values for x_lnnoptr must
626 * be adjusted by the amount that the line number section has moved
627 * in the file (bias computed in make_hdr). The #@$%&* designers of
628 * the auxiliary entry structures used the absolute file offsets for
629 * the line number entry rather than an offset from the start of the
630 * line number section!
632 * When I figure out how to scan through the symbol table and pick out
633 * the auxiliary entries that need adjustment, this routine will
634 * be fixed. As it is now, all such entries are wrong and sdb
635 * will complain. Fred Fish, UniSoft Systems Inc.
638 /* This function is probably very slow. Instead of reopening the new
639 file for input and output it should copy from the old to the new
640 using the two descriptors already open (WRITEDESC and READDESC).
641 Instead of reading one small structure at a time it should use
642 a reasonable size buffer. But I don't have time to work on such
643 things, so I am installing it as submitted to me. -- RMS. */
645 adjust_lnnoptrs (writedesc
, readdesc
, new_name
)
652 struct syment symentry
;
653 union auxent auxentry
;
655 if (!lnnoptr
|| !f_hdr
.f_symptr
)
659 if ((new = writedesc
) < 0)
661 if ((new = open (new_name
, O_RDWR
)) < 0)
668 lseek (new, f_hdr
.f_symptr
, 0);
669 for (nsyms
= 0; nsyms
< f_hdr
.f_nsyms
; nsyms
++)
671 read (new, &symentry
, SYMESZ
);
672 if (symentry
.n_numaux
)
674 read (new, &auxentry
, AUXESZ
);
676 if (ISFCN (symentry
.n_type
) || symentry
.n_type
== 0x2400)
678 auxentry
.x_sym
.x_fcnary
.x_fcn
.x_lnnoptr
+= bias
;
679 lseek (new, -AUXESZ
, 1);
680 write (new, &auxentry
, AUXESZ
);
690 extern unsigned start
__asm__ ("start");
693 * Return the address of the start of the text segment prior to
694 * doing an unexec. After unexec the return value is undefined.
695 * See crt0.c for further explanation and _start.
702 return ((char *) &start
);
705 /* ****************************************************************
710 unexec (new_name
, a_name
, data_start
, bss_start
, entry_address
)
711 char *new_name
, *a_name
;
712 unsigned data_start
, bss_start
, entry_address
;
716 if (a_name
&& (a_out
= open (a_name
, O_RDONLY
)) < 0)
720 if ((new = creat (new_name
, 0666)) < 0)
725 if (make_hdr (new, a_out
, data_start
, bss_start
, entry_address
, a_name
, new_name
) < 0
726 || copy_text_and_data (new, a_out
) < 0
727 || copy_sym (new, a_out
, a_name
, new_name
) < 0
728 || adjust_lnnoptrs (new, a_out
, new_name
) < 0
732 /* unlink (new_name); /* Failed, unlink new a.out */
743 #endif /* not CANNOT_DUMP */
745 /* arch-tag: 62409b69-e27a-4a7c-9413-0210d6b54e7f
746 (do not change this comment) */