Commit | Line | Data |
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1a63b3de RS |
1 | /* Unexec for Sunos 4 using shared libraries. |
2 | Copyright (C) 1990, 1994 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GNU Emacs. | |
5 | ||
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 2, or (at your option) | |
9 | any later version. | |
10 | ||
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. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GNU Emacs; see the file COPYING. If not, write to | |
3b7ad313 EN |
18 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
19 | Boston, MA 02111-1307, USA. */ | |
1a63b3de | 20 | |
2cad8dd6 | 21 | /* Contributed by Viktor Dukhovni. */ |
9889c728 JB |
22 | /* |
23 | * Unexec for Berkeley a.out format + SUNOS shared libraries | |
24 | * The unexeced executable contains the __DYNAMIC area from the | |
25 | * original text file, and then the rest of data + bss + malloced area of | |
26 | * the current process. (The __DYNAMIC area is at the top of the process | |
27 | * data segment, we use "data_start" defined externally to mark the start | |
28 | * of the "real" data segment.) | |
29 | * | |
30 | * For programs that want to remap some of the data segment read only | |
31 | * a run_time_remap is provided. This attempts to remap largest area starting | |
32 | * and ending on page boundaries between "data_start" and "bndry" | |
33 | * For this it to figure out where the text file is located. A path search | |
34 | * is attempted after trying argv[0] and if all fails we simply do not remap | |
35 | * | |
36 | * One feature of run_time_remap () is mandatory: reseting the break. | |
37 | * | |
38 | * Note that we can no longer map data into the text segment, as this causes | |
39 | * the __DYNAMIC struct to become read only, breaking the runtime loader. | |
40 | * Thus we no longer need to mess with a private crt0.c, the standard one | |
41 | * will do just fine, since environ can live in the writable area between | |
42 | * __DYNAMIC and data_start, just make sure that pre-crt0.o (the name | |
43 | * is somewhat abused here) is loaded first! | |
44 | * | |
9889c728 | 45 | */ |
9889c728 JB |
46 | #include <sys/param.h> |
47 | #include <sys/mman.h> | |
48 | #include <sys/file.h> | |
49 | #include <sys/stat.h> | |
50 | #include <string.h> | |
51 | #include <stdio.h> | |
52 | #include <a.out.h> | |
53 | ||
26e0a910 RM |
54 | /* Do this after the above #include's in case a configuration file wants |
55 | to define things for this file based on what <a.out.h> defines. */ | |
56 | #ifdef emacs | |
57 | #include <config.h> | |
58 | #endif | |
59 | ||
7d158964 | 60 | #if defined (SUNOS4) || defined (__FreeBSD__) || defined (__NetBSD__) |
ee3e4769 RS |
61 | #define UNDO_RELOCATION |
62 | #endif | |
63 | ||
64 | #ifdef UNDO_RELOCATION | |
1a63b3de RS |
65 | #include <link.h> |
66 | #endif | |
67 | ||
cda2316f RS |
68 | #ifdef HAVE_UNISTD_H |
69 | #include <unistd.h> | |
70 | #endif | |
26e0a910 | 71 | |
3b95c869 RM |
72 | /* NetBSD needs this bit, but SunOS does not have it. */ |
73 | #ifndef MAP_FILE | |
74 | #define MAP_FILE 0 | |
75 | #endif | |
76 | ||
77 | ||
9889c728 JB |
78 | /* |
79 | * for programs other than emacs | |
80 | * define data_start + initialized here, and make sure | |
81 | * this object is loaded first! | |
82 | * emacs will define these elsewhere, and load the object containing | |
83 | * data_start (pre-crt0.o or firstfile.o?) first! | |
84 | * The custom crt0.o *must not* be loaded! | |
85 | */ | |
86 | #ifndef emacs | |
87 | static int data_start = 0; | |
88 | static int initialized = 0; | |
89 | #else | |
90 | extern int initialized; | |
91 | extern unsigned data_start; | |
92 | extern int pureptr; | |
93 | #endif | |
94 | ||
95 | extern char *getenv (); | |
0c97bd6a | 96 | static unsigned brk_value; |
9889c728 JB |
97 | static struct exec nhdr; |
98 | static int rd_only_len; | |
99 | static long cookie; | |
100 | ||
101 | ||
102 | unexec (new_name, a_name, bndry, bss_start, entry) | |
103 | char *new_name, *a_name; | |
104 | unsigned bndry, bss_start, entry; | |
105 | { | |
9889c728 JB |
106 | int fd, new; |
107 | char *old; | |
108 | struct exec ohdr; /* Allocate on the stack, not needed in the next life */ | |
109 | struct stat stat; | |
110 | ||
9889c728 JB |
111 | if ((fd = open (a_name, O_RDONLY)) < 0) |
112 | { | |
113 | fprintf (stderr, "%s: open: ", a_name); | |
114 | perror (a_name); | |
115 | exit (1); | |
116 | } | |
117 | if ((new = open (new_name, O_WRONLY | O_CREAT, 0666)) == -1) | |
118 | { | |
119 | fprintf (stderr, "%s: open: ", a_name); | |
120 | perror (new_name); | |
121 | exit (1); | |
122 | } | |
123 | ||
124 | if ((fstat (fd, &stat) == -1)) | |
125 | { | |
126 | fprintf (stderr, "%s: ", a_name); | |
127 | perror ("fstat"); | |
128 | exit (1); | |
129 | } | |
130 | ||
3b95c869 | 131 | old = (char *)mmap (0, stat.st_size, PROT_READ, MAP_FILE|MAP_SHARED, fd, 0); |
9889c728 JB |
132 | if (old == (char *)-1) |
133 | { | |
134 | fprintf (stderr, "%s: ", a_name); | |
135 | perror ("mmap"); | |
136 | exit (1); | |
137 | } | |
138 | close (fd); | |
139 | ||
140 | nhdr = ohdr = (*(struct exec *)old); | |
141 | ||
142 | ||
143 | /* | |
eb8c3be9 JB |
144 | * Remember a magic cookie so we know we've got the right binary |
145 | * when remapping. | |
9889c728 JB |
146 | */ |
147 | cookie = time (0); | |
148 | ||
0c97bd6a RS |
149 | /* Save the break, it is reset to &_end (by ld.so?). */ |
150 | brk_value = (unsigned) sbrk (0); | |
9889c728 JB |
151 | |
152 | /* | |
153 | * Round up data start to a page boundary (Lose if not a 2 power!) | |
154 | */ | |
155 | data_start = ((((int)&data_start) - 1) & ~(N_PAGSIZ (nhdr) - 1)) + N_PAGSIZ (nhdr); | |
156 | ||
157 | /* | |
158 | * Round down read only pages to a multiple of the page size | |
159 | */ | |
160 | if (bndry) | |
161 | rd_only_len = ((int)bndry & ~(N_PAGSIZ (nhdr) - 1)) - data_start; | |
162 | ||
163 | #ifndef emacs | |
164 | /* Have to do this some time before dumping the data */ | |
165 | initialized = 1; | |
166 | #endif | |
167 | ||
0c97bd6a RS |
168 | /* Handle new data and bss sizes and optional new entry point. |
169 | No one actually uses bss_start and entry, but tradition compels | |
170 | one to support them. | |
171 | Could complain if bss_start > brk_value, | |
172 | but the caller is *supposed* to know what she is doing. */ | |
173 | nhdr.a_data = (bss_start ? bss_start : brk_value) - N_DATADDR (nhdr); | |
174 | nhdr.a_bss = bss_start ? brk_value - bss_start : 0; | |
9889c728 JB |
175 | if (entry) |
176 | nhdr.a_entry = entry; | |
177 | ||
178 | /* | |
179 | * Write out the text segment with new header | |
180 | * Dynamic executables are ZMAGIC with N_TXTOFF==0 and the header | |
181 | * part of the text segment, but no need to rely on this. | |
182 | * So write the TEXT first, then go back replace the header. | |
183 | * Doing it in the other order is less general! | |
184 | */ | |
185 | lseek (new, N_TXTOFF (nhdr), L_SET); | |
186 | write (new, old + N_TXTOFF (ohdr), N_TXTOFF (ohdr) + ohdr.a_text); | |
187 | lseek (new, 0L, L_SET); | |
188 | write (new, &nhdr, sizeof (nhdr)); | |
189 | ||
190 | /* | |
191 | * Write out the head of the old data segment from the file not | |
192 | * from core, this has the unresolved __DYNAMIC relocation data | |
193 | * we need to reload | |
194 | */ | |
195 | lseek (new, N_DATOFF (nhdr), L_SET); | |
196 | write (new, old + N_DATOFF (ohdr), (int)&data_start - N_DATADDR (ohdr)); | |
197 | ||
198 | /* | |
199 | * Copy the rest of the data from core | |
200 | */ | |
201 | write (new, &data_start, N_BSSADDR (nhdr) - (int)&data_start); | |
202 | ||
203 | /* | |
204 | * Copy the symbol table and line numbers | |
205 | */ | |
206 | lseek (new, N_TRELOFF (nhdr), L_SET); | |
207 | write (new, old + N_TRELOFF (ohdr), stat.st_size - N_TRELOFF (ohdr)); | |
208 | ||
1a63b3de RS |
209 | /* Some other BSD systems use this file. |
210 | We don't know whether this change is right for them. */ | |
ee3e4769 | 211 | #ifdef UNDO_RELOCATION |
1a63b3de RS |
212 | /* Undo the relocations done at startup by ld.so. |
213 | It will do these relocations again when we start the dumped Emacs. | |
214 | Doing them twice gives incorrect results. */ | |
215 | { | |
a783251b | 216 | unsigned long daddr = N_DATADDR (ohdr); |
1a63b3de | 217 | unsigned long rel, erel; |
ee3e4769 | 218 | #ifdef SUNOS4 |
499a514d | 219 | #ifdef SUNOS4_SHARED_LIBRARIES |
a783251b RS |
220 | extern struct link_dynamic _DYNAMIC; |
221 | ||
222 | /* SunOS4.x's ld_rel is relative to N_TXTADDR. */ | |
499a514d RS |
223 | if (!ohdr.a_dynamic) |
224 | /* This was statically linked. */ | |
225 | rel = erel = 0; | |
226 | else if (_DYNAMIC.ld_version < 2) | |
1a63b3de | 227 | { |
a783251b RS |
228 | rel = _DYNAMIC.ld_un.ld_1->ld_rel + N_TXTADDR (ohdr); |
229 | erel = _DYNAMIC.ld_un.ld_1->ld_hash + N_TXTADDR (ohdr); | |
1a63b3de RS |
230 | } |
231 | else | |
232 | { | |
a783251b RS |
233 | rel = _DYNAMIC.ld_un.ld_2->ld_rel + N_TXTADDR (ohdr); |
234 | erel = _DYNAMIC.ld_un.ld_2->ld_hash + N_TXTADDR (ohdr); | |
1a63b3de | 235 | } |
499a514d RS |
236 | #else /* not SUNOS4_SHARED_LIBRARIES */ |
237 | rel = erel = 0; | |
238 | #endif /* not SUNOS4_SHARED_LIBRARIES */ | |
a783251b RS |
239 | #ifdef sparc |
240 | #define REL_INFO_TYPE struct reloc_info_sparc | |
241 | #else | |
9629ced8 | 242 | #define REL_INFO_TYPE struct relocation_info |
a783251b RS |
243 | #endif /* sparc */ |
244 | #define REL_TARGET_ADDRESS(r) (((REL_INFO_TYPE *)(r))->r_address) | |
ee3e4769 | 245 | #endif /* SUNOS4 */ |
7d158964 | 246 | #if defined (__FreeBSD__) || defined (__NetBSD__) |
a783251b RS |
247 | extern struct _dynamic _DYNAMIC; |
248 | ||
249 | /* FreeBSD's LD_REL is a virtual address itself. */ | |
250 | rel = LD_REL (&_DYNAMIC); | |
251 | erel = rel + LD_RELSZ (&_DYNAMIC); | |
252 | #define REL_INFO_TYPE struct relocation_info | |
253 | #define REL_TARGET_ADDRESS(r) (((REL_INFO_TYPE *)(r))->r_address) | |
ee3e4769 | 254 | #endif |
1a63b3de | 255 | |
a783251b | 256 | for (; rel < erel; rel += sizeof (REL_INFO_TYPE)) |
1a63b3de | 257 | { |
a783251b RS |
258 | /* This is the virtual address where ld.so will do relocation. */ |
259 | unsigned long target = REL_TARGET_ADDRESS (rel); | |
260 | /* This is the offset in the data segment. */ | |
261 | unsigned long segoffset = target - daddr; | |
262 | ||
263 | /* If it is located below data_start, we have to do nothing here, | |
264 | because the old data has been already written to the location. */ | |
265 | if (target < (unsigned long)&data_start) | |
266 | continue; | |
267 | ||
268 | lseek (new, N_DATOFF (nhdr) + segoffset, L_SET); | |
269 | write (new, old + N_DATOFF (ohdr) + segoffset, sizeof (unsigned long)); | |
1a63b3de RS |
270 | } |
271 | } | |
ee3e4769 | 272 | #endif /* UNDO_RELOCATION */ |
1a63b3de | 273 | |
9889c728 JB |
274 | fchmod (new, 0755); |
275 | } | |
276 | ||
277 | void | |
278 | run_time_remap (progname) | |
279 | char *progname; | |
280 | { | |
281 | char aout[MAXPATHLEN]; | |
282 | register char *path, *p; | |
283 | ||
284 | /* Just in case */ | |
285 | if (!initialized) | |
286 | return; | |
287 | ||
288 | /* Restore the break */ | |
0c97bd6a | 289 | brk ((char *) brk_value); |
9889c728 JB |
290 | |
291 | /* If nothing to remap: we are done! */ | |
292 | if (rd_only_len == 0) | |
293 | return; | |
294 | ||
295 | /* | |
296 | * Attempt to find the executable | |
297 | * First try argv[0], will almost always succeed as shells tend to give | |
298 | * the full path from the hash list rather than using execvp () | |
299 | */ | |
300 | if (is_it (progname)) | |
301 | return; | |
302 | ||
303 | /* | |
304 | * If argv[0] is a full path and does not exist, not much sense in | |
305 | * searching further | |
306 | */ | |
307 | if (strchr (progname, '/')) | |
308 | return; | |
309 | ||
310 | /* | |
311 | * Try to search for argv[0] on the PATH | |
312 | */ | |
313 | path = getenv ("PATH"); | |
314 | if (path == NULL) | |
315 | return; | |
316 | ||
317 | while (*path) | |
318 | { | |
319 | /* copy through ':' or end */ | |
320 | for (p = aout; *p = *path; ++p, ++path) | |
321 | if (*p == ':') | |
322 | { | |
323 | ++path; /* move past ':' */ | |
324 | break; | |
325 | } | |
326 | *p++ = '/'; | |
327 | strcpy (p, progname); | |
328 | /* | |
329 | * aout is a candidate full path name | |
330 | */ | |
331 | if (is_it (aout)) | |
332 | return; | |
333 | } | |
334 | } | |
335 | ||
a783251b RS |
336 | is_it (filename) |
337 | char *filename; | |
9889c728 JB |
338 | { |
339 | int fd; | |
a783251b | 340 | long filenames_cookie; |
9889c728 JB |
341 | struct exec hdr; |
342 | ||
343 | /* | |
344 | * Open an executable and check for a valid header! | |
a783251b | 345 | * Can't bcmp the header with what we had, it may have been stripped! |
9889c728 JB |
346 | * so we may save looking at non executables with the same name, mostly |
347 | * directories. | |
348 | */ | |
a783251b | 349 | fd = open (filename, O_RDONLY); |
9889c728 JB |
350 | if (fd != -1) |
351 | { | |
352 | if (read (fd, &hdr, sizeof (hdr)) == sizeof (hdr) | |
353 | && !N_BADMAG (hdr) && N_DATOFF (hdr) == N_DATOFF (nhdr) | |
354 | && N_TRELOFF (hdr) == N_TRELOFF (nhdr)) | |
355 | { | |
356 | /* compare cookies */ | |
357 | lseek (fd, N_DATOFF (hdr) + (int)&cookie - N_DATADDR (hdr), L_SET); | |
a783251b RS |
358 | read (fd, &filenames_cookie, sizeof (filenames_cookie)); |
359 | if (filenames_cookie == cookie) | |
9889c728 JB |
360 | { /* Eureka */ |
361 | ||
362 | /* | |
363 | * Do the mapping | |
364 | * The PROT_EXEC may not be needed, but it is safer this way. | |
365 | * should the shared library decide to indirect through | |
366 | * addresses in the data segment not part of __DYNAMIC | |
367 | */ | |
0c97bd6a | 368 | mmap ((char *) data_start, rd_only_len, PROT_READ | PROT_EXEC, |
3b95c869 | 369 | MAP_FILE | MAP_SHARED | MAP_FIXED, fd, |
9889c728 JB |
370 | N_DATOFF (hdr) + data_start - N_DATADDR (hdr)); |
371 | close (fd); | |
372 | return 1; | |
373 | } | |
374 | } | |
375 | close (fd); | |
376 | } | |
377 | return 0; | |
378 | } |