1 /* Copyright (C) 1985-1988, 1992-1994, 2001-2012 Free Software Foundation, Inc.
3 This file is part of GNU Emacs.
5 GNU Emacs is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 GNU Emacs is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
20 * unexcoff.c - Convert a running program into an a.out or COFF file.
22 * ==================================================================
23 * Note: This file is currently used only by the MSDOS (a.k.a. DJGPP)
24 * build of Emacs. If you are not interested in the MSDOS build, you
25 * are looking at the wrong version of unexec!
26 * ==================================================================
28 * Author: Spencer W. Thomas
29 * Computer Science Dept.
31 * Date: Tue Mar 2 1982
32 * Originally under the name unexec.c.
33 * Modified heavily since then.
36 * unexec (const char *new_name, const char *old_name);
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 * If you make improvements I'd like to get them too.
44 * harpo!utah-cs!thomas, thomas@Utah-20
48 /* Modified to support SysVr3 shared libraries by James Van Artsdalen
49 * of Dell Computer Corporation. james@bigtex.cactus.org.
55 #define PERROR(file) report_error (file, new)
57 #ifndef CANNOT_DUMP /* all rest of file! */
62 #include <fcntl.h> /* for O_RDONLY, O_RDWR */
63 #include <crt0.h> /* for _crt0_startup_flags and its bits */
64 #include <sys/exceptn.h>
65 static int save_djgpp_startup_flags
;
66 #define filehdr external_filehdr
67 #define scnhdr external_scnhdr
68 #define syment external_syment
69 #define auxent external_auxent
70 #define n_numaux e_numaux
74 unsigned short magic
; /* type of file */
75 unsigned short vstamp
; /* version stamp */
76 unsigned long tsize
; /* text size in bytes, padded to FW bdry*/
77 unsigned long dsize
; /* initialized data " " */
78 unsigned long bsize
; /* uninitialized data " " */
79 unsigned long entry
; /* entry pt. */
80 unsigned long text_start
;/* base of text used for this file */
81 unsigned long data_start
;/* base of data used for this file */
83 #endif /* not MSDOS */
84 #else /* not HAVE_COFF_H */
86 #endif /* not HAVE_COFF_H */
88 /* Define getpagesize if the system does not.
89 Note that this may depend on symbols defined in a.out.h. */
90 #include "getpagesize.h"
92 #ifndef makedev /* Try to detect types.h already loaded */
93 #include <sys/types.h>
101 #include "mem-limits.h"
103 static long block_copy_start
; /* Old executable start point */
104 static struct filehdr f_hdr
; /* File header */
105 static struct aouthdr f_ohdr
; /* Optional file header (a.out) */
106 long bias
; /* Bias to add for growth */
107 long lnnoptr
; /* Pointer to line-number info within file */
108 #define SYMS_START block_copy_start
110 static long text_scnptr
;
111 static long data_scnptr
;
113 static long coff_offset
;
117 /* Correct an int which is the bit pattern of a pointer to a byte
118 into an int which is the number of a byte.
119 This is a no-op on ordinary machines, but not on all. */
121 #define ADDR_CORRECT(x) ((char *)(x) - (char*)0)
126 report_error (const char *file
, int fd
)
130 report_file_error ("Cannot unexec", Fcons (build_string (file
), Qnil
));
133 #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1
134 #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1
135 #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1
138 report_error_1 (int fd
, const char *msg
, int a1
, int a2
)
144 static int make_hdr (int, int, const char *, const char *);
145 static int copy_text_and_data (int, int);
146 static int copy_sym (int, int, const char *, const char *);
147 static void mark_x (const char *);
149 /* ****************************************************************
152 * Make the header in the new a.out from the header in core.
153 * Modify the text and data sizes.
156 make_hdr (int new, int a_out
,
157 const char *a_name
, const char *new_name
)
159 auto struct scnhdr f_thdr
; /* Text section header */
160 auto struct scnhdr f_dhdr
; /* Data section header */
161 auto struct scnhdr f_bhdr
; /* Bss section header */
162 auto struct scnhdr scntemp
; /* Temporary section header */
164 unsigned int bss_start
;
165 unsigned int data_start
;
167 pagemask
= getpagesize () - 1;
169 /* Adjust text/data boundary. */
170 data_start
= (int) start_of_data ();
171 data_start
= ADDR_CORRECT (data_start
);
172 data_start
= data_start
& ~pagemask
; /* (Down) to page boundary. */
174 bss_start
= ADDR_CORRECT (sbrk (0)) + pagemask
;
175 bss_start
&= ~ pagemask
;
177 if (data_start
> bss_start
) /* Can't have negative data size. */
179 ERROR2 ("unexec: data_start (%u) can't be greater than bss_start (%u)",
180 data_start
, bss_start
);
183 coff_offset
= 0L; /* stays zero, except in DJGPP */
185 /* Salvage as much info from the existing file as possible */
189 /* Support the coff-go32-exe format with a prepended stub, since
190 this is what GCC 2.8.0 and later generates by default in DJGPP. */
191 unsigned short mz_header
[3];
193 if (read (a_out
, &mz_header
, sizeof (mz_header
)) != sizeof (mz_header
))
197 if (mz_header
[0] == 0x5a4d || mz_header
[0] == 0x4d5a) /* "MZ" or "ZM" */
199 coff_offset
= (long)mz_header
[2] * 512L;
201 coff_offset
+= (long)mz_header
[1] - 512L;
202 lseek (a_out
, coff_offset
, 0);
205 lseek (a_out
, 0L, 0);
207 if (read (a_out
, &f_hdr
, sizeof (f_hdr
)) != sizeof (f_hdr
))
211 block_copy_start
+= sizeof (f_hdr
);
212 if (f_hdr
.f_opthdr
> 0)
214 if (read (a_out
, &f_ohdr
, sizeof (f_ohdr
)) != sizeof (f_ohdr
))
218 block_copy_start
+= sizeof (f_ohdr
);
220 /* Loop through section headers, copying them in */
221 lseek (a_out
, coff_offset
+ sizeof (f_hdr
) + f_hdr
.f_opthdr
, 0);
222 for (scns
= f_hdr
.f_nscns
; scns
> 0; scns
--) {
223 if (read (a_out
, &scntemp
, sizeof (scntemp
)) != sizeof (scntemp
))
227 if (scntemp
.s_scnptr
> 0L)
229 if (block_copy_start
< scntemp
.s_scnptr
+ scntemp
.s_size
)
230 block_copy_start
= scntemp
.s_scnptr
+ scntemp
.s_size
;
232 if (strcmp (scntemp
.s_name
, ".text") == 0)
236 else if (strcmp (scntemp
.s_name
, ".data") == 0)
240 else if (strcmp (scntemp
.s_name
, ".bss") == 0)
248 ERROR0 ("can't build a COFF file from scratch yet");
251 /* Now we alter the contents of all the f_*hdr variables
252 to correspond to what we want to dump. */
254 f_hdr
.f_flags
|= (F_RELFLG
| F_EXEC
);
255 f_ohdr
.dsize
= bss_start
- f_ohdr
.data_start
;
257 f_thdr
.s_size
= f_ohdr
.tsize
;
258 f_thdr
.s_scnptr
= sizeof (f_hdr
) + sizeof (f_ohdr
);
259 f_thdr
.s_scnptr
+= (f_hdr
.f_nscns
) * (sizeof (f_thdr
));
260 lnnoptr
= f_thdr
.s_lnnoptr
;
261 text_scnptr
= f_thdr
.s_scnptr
;
262 f_dhdr
.s_paddr
= f_ohdr
.data_start
;
263 f_dhdr
.s_vaddr
= f_ohdr
.data_start
;
264 f_dhdr
.s_size
= f_ohdr
.dsize
;
265 f_dhdr
.s_scnptr
= f_thdr
.s_scnptr
+ f_thdr
.s_size
;
266 data_scnptr
= f_dhdr
.s_scnptr
;
267 f_bhdr
.s_paddr
= f_ohdr
.data_start
+ f_ohdr
.dsize
;
268 f_bhdr
.s_vaddr
= f_ohdr
.data_start
+ f_ohdr
.dsize
;
269 f_bhdr
.s_size
= f_ohdr
.bsize
;
270 f_bhdr
.s_scnptr
= 0L;
271 bias
= f_dhdr
.s_scnptr
+ f_dhdr
.s_size
- block_copy_start
;
273 if (f_hdr
.f_symptr
> 0L)
275 f_hdr
.f_symptr
+= bias
;
278 if (f_thdr
.s_lnnoptr
> 0L)
280 f_thdr
.s_lnnoptr
+= bias
;
283 if (write (new, &f_hdr
, sizeof (f_hdr
)) != sizeof (f_hdr
))
288 if (write (new, &f_ohdr
, sizeof (f_ohdr
)) != sizeof (f_ohdr
))
293 if (write (new, &f_thdr
, sizeof (f_thdr
)) != sizeof (f_thdr
))
298 if (write (new, &f_dhdr
, sizeof (f_dhdr
)) != sizeof (f_dhdr
))
303 if (write (new, &f_bhdr
, sizeof (f_bhdr
)) != sizeof (f_bhdr
))
313 write_segment (int new, const char *ptr
, const char *end
)
315 register int i
, nwrite
, ret
;
316 /* This is the normal amount to write at once.
317 It is the size of block that NFS uses. */
318 int writesize
= 1 << 13;
319 int pagesize
= getpagesize ();
322 memset (zeros
, 0, sizeof (zeros
));
324 for (i
= 0; ptr
< end
;)
326 /* Distance to next multiple of writesize. */
327 nwrite
= (((int) ptr
+ writesize
) & -writesize
) - (int) ptr
;
328 /* But not beyond specified end. */
329 if (nwrite
> end
- ptr
) nwrite
= end
- ptr
;
330 ret
= write (new, ptr
, nwrite
);
331 /* If write gets a page fault, it means we reached
332 a gap between the old text segment and the old data segment.
333 This gap has probably been remapped into part of the text segment.
334 So write zeros for it. */
335 if (ret
== -1 && errno
== EFAULT
)
337 /* Write only a page of zeros at once,
338 so that we don't overshoot the start
339 of the valid memory in the old data segment. */
340 if (nwrite
> pagesize
)
342 write (new, zeros
, nwrite
);
348 /* ****************************************************************
351 * Copy the text and data segments from memory to the new a.out
354 copy_text_and_data (int new, int a_out
)
360 /* Dump the original table of exception handlers, not the one
361 where our exception hooks are registered. */
362 __djgpp_exception_toggle ();
364 /* Switch off startup flags that might have been set at runtime
365 and which might change the way that dumped Emacs works. */
366 save_djgpp_startup_flags
= _crt0_startup_flags
;
367 _crt0_startup_flags
&= ~(_CRT0_FLAG_NO_LFN
| _CRT0_FLAG_NEARPTR
);
370 lseek (new, (long) text_scnptr
, 0);
371 ptr
= (char *) f_ohdr
.text_start
;
372 end
= ptr
+ f_ohdr
.tsize
;
373 write_segment (new, ptr
, end
);
375 lseek (new, (long) data_scnptr
, 0);
376 ptr
= (char *) f_ohdr
.data_start
;
377 end
= ptr
+ f_ohdr
.dsize
;
378 write_segment (new, ptr
, end
);
381 /* Restore our exception hooks. */
382 __djgpp_exception_toggle ();
384 /* Restore the startup flags. */
385 _crt0_startup_flags
= save_djgpp_startup_flags
;
392 /* ****************************************************************
395 * Copy the relocation information and symbol table from the a.out to the new
398 copy_sym (int new, int a_out
, const char *a_name
, const char *new_name
)
406 if (SYMS_START
== 0L)
409 if (lnnoptr
) /* if there is line number info */
410 lseek (a_out
, coff_offset
+ lnnoptr
, 0); /* start copying from there */
412 lseek (a_out
, coff_offset
+ SYMS_START
, 0); /* Position a.out to symtab. */
414 while ((n
= read (a_out
, page
, sizeof page
)) > 0)
416 if (write (new, page
, n
) != n
)
428 /* ****************************************************************
431 * After successfully building the new a.out, mark it executable
434 mark_x (const char *name
)
438 int new = 0; /* for PERROR */
442 if (stat (name
, &sbuf
) == -1)
446 sbuf
.st_mode
|= 0111 & ~um
;
447 if (chmod (name
, sbuf
.st_mode
) == -1)
453 * If the COFF file contains a symbol table and a line number section,
454 * then any auxiliary entries that have values for x_lnnoptr must
455 * be adjusted by the amount that the line number section has moved
456 * in the file (bias computed in make_hdr). The #@$%&* designers of
457 * the auxiliary entry structures used the absolute file offsets for
458 * the line number entry rather than an offset from the start of the
459 * line number section!
461 * When I figure out how to scan through the symbol table and pick out
462 * the auxiliary entries that need adjustment, this routine will
463 * be fixed. As it is now, all such entries are wrong and sdb
464 * will complain. Fred Fish, UniSoft Systems Inc.
467 /* This function is probably very slow. Instead of reopening the new
468 file for input and output it should copy from the old to the new
469 using the two descriptors already open (WRITEDESC and READDESC).
470 Instead of reading one small structure at a time it should use
471 a reasonable size buffer. But I don't have time to work on such
472 things, so I am installing it as submitted to me. -- RMS. */
475 adjust_lnnoptrs (int writedesc
, int readdesc
, const char *new_name
)
479 struct syment symentry
;
480 union auxent auxentry
;
482 if (!lnnoptr
|| !f_hdr
.f_symptr
)
486 if ((new = writedesc
) < 0)
488 if ((new = open (new_name
, O_RDWR
)) < 0)
495 lseek (new, f_hdr
.f_symptr
, 0);
496 for (nsyms
= 0; nsyms
< f_hdr
.f_nsyms
; nsyms
++)
498 read (new, &symentry
, SYMESZ
);
499 if (symentry
.n_numaux
)
501 read (new, &auxentry
, AUXESZ
);
503 if (ISFCN (symentry
.n_type
) || symentry
.n_type
== 0x2400)
505 auxentry
.x_sym
.x_fcnary
.x_fcn
.x_lnnoptr
+= bias
;
506 lseek (new, -AUXESZ
, 1);
507 write (new, &auxentry
, AUXESZ
);
517 /* ****************************************************************
523 unexec (const char *new_name
, const char *a_name
)
525 int new = -1, a_out
= -1;
527 if (a_name
&& (a_out
= open (a_name
, O_RDONLY
)) < 0)
531 if ((new = creat (new_name
, 0666)) < 0)
536 if (make_hdr (new, a_out
, a_name
, new_name
) < 0
537 || copy_text_and_data (new, a_out
) < 0
538 || copy_sym (new, a_out
, a_name
, new_name
) < 0
539 || adjust_lnnoptrs (new, a_out
, new_name
) < 0
552 #endif /* not CANNOT_DUMP */