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comparison src/unexhp9k800.c @ 428:3ecd8885ac67 r21-2-22

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date Mon, 13 Aug 2007 11:28:15 +0200
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1 /* Unexec for HP 9000 Series 800 machines.
2 Bob Desinger <hpsemc!bd@hplabs.hp.com>
3
4 This file is part of XEmacs.
5
6 XEmacs is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 2, or (at your option) any
9 later version.
10
11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with XEmacs; see the file COPYING. If not, write to
18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
20
21 /* Synched up with: Not synched with FSF. */
22
23 /*
24
25 Unexec creates a copy of the old a.out file, and replaces the old data
26 area with the current data area. When the new file is executed, the
27 process will see the same data structures and data values that the
28 original process had when unexec was called.
29
30 Unlike other versions of unexec, this one copies symbol table and
31 debug information to the new a.out file. Thus, the new a.out file
32 may be debugged with symbolic debuggers.
33
34 If you fix any bugs in this, I'd like to incorporate your fixes.
35 Send them to uunet!hpda!hpsemc!jmorris or jmorris%hpsemc@hplabs.HP.COM.
36
37 CAVEATS:
38 This routine saves the current value of all static and external
39 variables. This means that any data structure that needs to be
40 initialized must be explicitly reset. Variables will not have their
41 expected default values.
42
43 Unfortunately, the HP-UX signal handler has internal initialization
44 flags which are not explicitly reset. Thus, for signals to work in
45 conjunction with this routine, the following code must executed when
46 the new process starts up.
47
48 void _sigreturn();
49 ...
50 sigsetreturn(_sigreturn);
51 */
52
53
54 #include <config.h>
55 #include <stdio.h>
56 #include <fcntl.h>
57 #include <errno.h>
58
59 #include <a.out.h>
60
61 /*
62 * Minor modification to enable dumping with shared libraries added by
63 * Dipankar Gupta (dg@hplb.hpl.hp.com). I studied Oliver Laumann's
64 * more elaborate dynamic loading scheme in ELK while implementing
65 * this, but don't use any of his machinery.
66 *
67 * Stores the BRK value at dump time, and uses the RUN_TIME_REMAP hook
68 * to break back to the stored value when the dumped executable is restarted.
69 *
70 * CAVEATS (addenda):
71 * 1. Text area of the shlibs are not stored. Thus, if a shared library is
72 * replaced between the time of dump and execution, all bets are off.
73 *
74 * 2. Assumes that the data and bss area are adjacent, which is true of the
75 * current VM implementation.
76 *
77 * 3. Any setup that defines HPUX_USE_SHLIBS *must* also define
78 * RUN_TIME_REMAP.
79 */
80
81 #ifdef HPUX_USE_SHLIBS
82 #include <dl.h> /* User-space dynamic loader entry points */
83 void Save_Shared_Data();
84 int run_time_remap();
85 #endif
86
87 #define min(x,y) ( ((x)<(y))?(x):(y) )
88
89 void write_header(int file, struct header *hdr, struct som_exec_auxhdr *auxhdr);
90 void read_header (int file, struct header *hdr, struct som_exec_auxhdr *auxhdr);
91 void save_data_space (int file, struct header *hdr,
92 struct som_exec_auxhdr *auxhdr, int size);
93 void copy_rest (int old, int new);
94 void copy_file (int old, int new, int size);
95 void update_file_ptrs(int file, struct header *hdr,
96 struct som_exec_auxhdr *auxhdr,
97 unsigned int location, int offset);
98 int calculate_checksum(struct header *hdr);
99
100 /* Create a new a.out file, same as old but with current data space */
101 int
102 unexec(char new_name[], /* name of the new a.out file to be created */
103 char old_name[], /* name of the old a.out file */
104 char *new_end_of_text, /* ptr to new edata/etext; NOT USED YET */
105 int dummy1, int dummy2) /* not used by emacs */
106 {
107 int old, new;
108 int old_size, new_size;
109 struct header hdr;
110 struct som_exec_auxhdr auxhdr;
111 long i;
112
113 /* For the greatest flexibility, should create a temporary file in
114 the same directory as the new file. When everything is complete,
115 rename the temp file to the new name.
116 This way, a program could update its own a.out file even while
117 it is still executing. If problems occur, everything is still
118 intact. NOT implemented. */
119
120 /* Open the input and output a.out files */
121 old = open (old_name, O_RDONLY);
122 if (old < 0)
123 { perror(old_name); exit(1); }
124 new = open (new_name, O_CREAT|O_RDWR|O_TRUNC, 0777);
125 if (new < 0)
126 { perror(new_name); exit(1); }
127
128 /* Read the old headers */
129 read_header(old, &hdr, &auxhdr);
130
131 #ifdef HPUX_USE_SHLIBS
132 Save_Shared_Data(); /* Save break value (added: dg@hplb.hpl.hp.com) */
133 #endif
134 /* Decide how large the new and old data areas are */
135 old_size = auxhdr.exec_dsize;
136 /* I suspect these two statements are separate
137 to avoid a compiler bug in hpux version 8. */
138 i = (long) sbrk (0);
139 new_size = i - auxhdr.exec_dmem;
140
141 /* Copy the old file to the new, up to the data space */
142 lseek(old, 0, 0);
143 copy_file(old, new, auxhdr.exec_dfile);
144
145 /* Skip the old data segment and write a new one */
146 lseek(old, old_size, 1);
147 save_data_space(new, &hdr, &auxhdr, new_size);
148
149 /* Copy the rest of the file */
150 copy_rest(old, new);
151
152 /* Update file pointers since we probably changed size of data area */
153 update_file_ptrs(new, &hdr, &auxhdr, auxhdr.exec_dfile, new_size-old_size);
154
155 /* Save the modified header */
156 write_header(new, &hdr, &auxhdr);
157
158 /* Close the binary file */
159 close (old);
160 close (new);
161 return 0;
162 }
163
164 /* Save current data space in the file, update header. */
165
166 void
167 save_data_space (int file, struct header *hdr,
168 struct som_exec_auxhdr *auxhdr, int size)
169 {
170 /* Write the entire data space out to the file */
171 if (write(file, (void *)auxhdr->exec_dmem, size) != size)
172 { perror("Can't save new data space"); exit(1); }
173
174 /* Update the header to reflect the new data size */
175 auxhdr->exec_dsize = size;
176 auxhdr->exec_bsize = 0;
177 }
178
179 /* Update the values of file pointers when something is inserted. */
180
181 void
182 update_file_ptrs(int file, struct header *hdr,
183 struct som_exec_auxhdr *auxhdr,
184 unsigned int location, int offset)
185 {
186 struct subspace_dictionary_record subspace;
187 int i;
188
189 /* Increase the overall size of the module */
190 hdr->som_length += offset;
191
192 /* Update the various file pointers in the header */
193 #define update(ptr) if (ptr > location) ptr = ptr + offset
194 update(hdr->aux_header_location);
195 update(hdr->space_strings_location);
196 update(hdr->init_array_location);
197 update(hdr->compiler_location);
198 update(hdr->symbol_location);
199 update(hdr->fixup_request_location);
200 update(hdr->symbol_strings_location);
201 update(hdr->unloadable_sp_location);
202 update(auxhdr->exec_tfile);
203 update(auxhdr->exec_dfile);
204
205 /* Do for each subspace dictionary entry */
206 lseek(file, hdr->subspace_location, 0);
207 for (i = 0; i < hdr->subspace_total; i++)
208 {
209 if (read(file, &subspace, sizeof(subspace)) != sizeof(subspace))
210 { perror("Can't read subspace record"); exit(1); }
211
212 /* If subspace has a file location, update it */
213 if (subspace.initialization_length > 0
214 && subspace.file_loc_init_value > location)
215 {
216 subspace.file_loc_init_value += offset;
217 lseek(file, -sizeof(subspace), 1);
218 if (write(file, &subspace, sizeof(subspace)) != sizeof(subspace))
219 { perror("Can't update subspace record"); exit(1); }
220 }
221 }
222
223 /* Do for each initialization pointer record */
224 /* (I don't think it applies to executable files, only relocatables) */
225 #undef update
226 }
227
228 /* Read in the header records from an a.out file. */
229
230 void
231 read_header(int file, struct header *hdr, struct som_exec_auxhdr *auxhdr)
232 {
233
234 /* Read the header in */
235 lseek(file, 0, 0);
236 if (read(file, hdr, sizeof(*hdr)) != sizeof(*hdr))
237 { perror("Couldn't read header from a.out file"); exit(1); }
238
239 if (hdr->a_magic != EXEC_MAGIC && hdr->a_magic != SHARE_MAGIC
240 && hdr->a_magic != DEMAND_MAGIC)
241 {
242 fprintf(stderr, "a.out file doesn't have legal magic number\n");
243 exit(1);
244 }
245
246 lseek(file, hdr->aux_header_location, 0);
247 if (read(file, auxhdr, sizeof(*auxhdr)) != sizeof(*auxhdr))
248 {
249 perror("Couldn't read auxiliary header from a.out file");
250 exit(1);
251 }
252 }
253
254 /* Write out the header records into an a.out file. */
255 void
256 write_header(int file, struct header *hdr, struct som_exec_auxhdr *auxhdr)
257 {
258 /* Update the checksum */
259 hdr->checksum = calculate_checksum(hdr);
260
261 /* Write the header back into the a.out file */
262 lseek(file, 0, 0);
263 if (write(file, hdr, sizeof(*hdr)) != sizeof(*hdr))
264 { perror("Couldn't write header to a.out file"); exit(1); }
265 lseek(file, hdr->aux_header_location, 0);
266 if (write(file, auxhdr, sizeof(*auxhdr)) != sizeof(*auxhdr))
267 { perror("Couldn't write auxiliary header to a.out file"); exit(1); }
268 }
269
270 /* Calculate the checksum of a SOM header record. */
271 int
272 calculate_checksum(struct header *hdr)
273 {
274 int checksum, i, *ptr;
275
276 checksum = 0; ptr = (int *) hdr;
277
278 for (i=0; i<sizeof(*hdr)/sizeof(int)-1; i++)
279 checksum ^= ptr[i];
280
281 return(checksum);
282 }
283
284 /* Copy size bytes from the old file to the new one. */
285 void
286 copy_file (int old, int new, int size)
287 {
288 int len;
289 int buffer[8192]; /* word aligned will be faster */
290
291 for (; size > 0; size -= len)
292 {
293 len = min(size, sizeof(buffer));
294 if (read(old, buffer, len) != len)
295 { perror("Read failure on a.out file"); exit(1); }
296 if (write(new, buffer, len) != len)
297 { perror("Write failure in a.out file"); exit(1); }
298 }
299 }
300
301 /* Copy the rest of the file, up to EOF. */
302 void
303 copy_rest (int old, int new)
304 {
305 int buffer[4096];
306 int len;
307
308 /* Copy bytes until end of file or error */
309 while ( (len = read(old, buffer, sizeof(buffer))) > 0)
310 if (write(new, buffer, len) != len) break;
311
312 if (len != 0)
313 { perror("Unable to copy the rest of the file"); exit(1); }
314 }
315
316 #ifdef DEBUG
317 display_header(struct header *hdr, struct som_exec_auxhdr *auxhdr)
318 {
319 /* Display the header information (debug) */
320 printf("\n\nFILE HEADER\n");
321 printf("magic number %d \n", hdr->a_magic);
322 printf("text loc %.8x size %d \n", auxhdr->exec_tmem, auxhdr->exec_tsize);
323 printf("data loc %.8x size %d \n", auxhdr->exec_dmem, auxhdr->exec_dsize);
324 printf("entry %x \n", auxhdr->exec_entry);
325 printf("Bss segment size %u\n", auxhdr->exec_bsize);
326 printf("\n");
327 printf("data file loc %d size %d\n",
328 auxhdr->exec_dfile, auxhdr->exec_dsize);
329 printf("som_length %d\n", hdr->som_length);
330 printf("unloadable sploc %d size %d\n",
331 hdr->unloadable_sp_location, hdr->unloadable_sp_size);
332 }
333 #endif /* DEBUG */
334
335 #ifdef HPUX_USE_SHLIBS
336 /* Added machinery for shared libs... see comments at the beginning of this file. */
337
338 void *Brk_On_Dump = 0; /* Brk value to restore... stored as a global */
339
340 void Save_Shared_Data () {
341 Brk_On_Dump = sbrk( 0 );
342 }
343
344 void Restore_Shared_Data () {
345 brk ( Brk_On_Dump );
346 }
347
348 int run_time_remap (int d) {
349 Restore_Shared_Data();
350 }
351
352 /* run_time_remap is the magic called by startup code in the dumped executable
353 * if RUN_TIME_REMAP is set.
354 */
355 #endif /* HPUX_USE_SHLIBS */