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[emacs.git] / src / unexhp9k800.c
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1 /* Unexec for HP 9000 Series 800 machines.
3 This file is in the public domain.
5 Author: John V. Morris
7 This file was written by John V. Morris at Hewlett Packard.
8 Both the author and Hewlett Packard Co. have disclaimed the
9 copyright on this file, and it is therefore in the public domain.
10 (Search for "hp9k800" in copyright.list.)
14 Bob Desinger <hpsemc!bd@hplabs.hp.com>
16 Note that the GNU project considers support for HP operation a
17 peripheral activity which should not be allowed to divert effort
18 from development of the GNU system. Changes in this code will be
19 installed when users send them in, but aside from that we don't
20 plan to think about it, or about whether other Emacs maintenance
21 might break it.
24 Unexec creates a copy of the old a.out file, and replaces the old data
25 area with the current data area. When the new file is executed, the
26 process will see the same data structures and data values that the
27 original process had when unexec was called.
29 Unlike other versions of unexec, this one copies symbol table and
30 debug information to the new a.out file. Thus, the new a.out file
31 may be debugged with symbolic debuggers.
33 If you fix any bugs in this, I'd like to incorporate your fixes.
34 Send them to uunet!hpda!hpsemc!jmorris or jmorris%hpsemc@hplabs.HP.COM.
36 CAVEATS:
37 This routine saves the current value of all static and external
38 variables. This means that any data structure that needs to be
39 initialized must be explicitly reset. Variables will not have their
40 expected default values.
42 Unfortunately, the HP-UX signal handler has internal initialization
43 flags which are not explicitly reset. Thus, for signals to work in
44 conjunction with this routine, the following code must executed when
45 the new process starts up.
47 void _sigreturn ();
48 ...
49 sigsetreturn (_sigreturn);
52 #include <config.h>
53 #include "unexec.h"
54 #include "lisp.h"
56 #include <stdio.h>
57 #include <fcntl.h>
58 #include <errno.h>
59 #include <a.out.h>
60 #include <dl.h>
62 /* brk value to restore, stored as a global.
63 This is really used only if we used shared libraries. */
64 static long brk_on_dump = 0;
66 /* Called from main, if we use shared libraries. */
67 int
68 run_time_remap (char *ignored)
70 brk ((char *) brk_on_dump);
73 #undef roundup
74 #define roundup(x,n) (((x) + ((n) - 1)) & ~((n) - 1)) /* n is power of 2 */
76 /* Report a fatal error and exit. */
77 static _Noreturn void
78 unexec_error (char const *msg)
80 perror (msg);
81 exit (1);
84 /* Do an lseek and check the result. */
85 static void
86 check_lseek (int fd, off_t offset, int whence)
88 if (lseek (fd, offset, whence) < 0)
89 unexec_error ("Cannot lseek");
92 /* Save current data space in the file, update header. */
94 static void
95 save_data_space (int file, struct header *hdr, struct som_exec_auxhdr *auxhdr,
96 int size)
98 /* Write the entire data space out to the file */
99 if (write (file, auxhdr->exec_dmem, size) != size)
100 unexec_error ("Can't save new data space");
102 /* Update the header to reflect the new data size */
103 auxhdr->exec_dsize = size;
104 auxhdr->exec_bsize = 0;
107 /* Update the values of file pointers when something is inserted. */
109 static void
110 update_file_ptrs (int file, struct header *hdr, struct som_exec_auxhdr *auxhdr,
111 unsigned int location, int offset)
113 struct subspace_dictionary_record subspace;
114 int i;
116 /* Increase the overall size of the module */
117 hdr->som_length += offset;
119 /* Update the various file pointers in the header */
120 #define update(ptr) if (ptr > location) ptr = ptr + offset
121 update (hdr->aux_header_location);
122 update (hdr->space_strings_location);
123 update (hdr->init_array_location);
124 update (hdr->compiler_location);
125 update (hdr->symbol_location);
126 update (hdr->fixup_request_location);
127 update (hdr->symbol_strings_location);
128 update (hdr->unloadable_sp_location);
129 update (auxhdr->exec_tfile);
130 update (auxhdr->exec_dfile);
132 /* Do for each subspace dictionary entry */
133 check_lseek (file, hdr->subspace_location, 0);
134 for (i = 0; i < hdr->subspace_total; i++)
136 ptrdiff_t subspace_size = sizeof subspace;
137 if (read (file, &subspace, subspace_size) != subspace_size)
138 unexec_error ("Can't read subspace record");
140 /* If subspace has a file location, update it */
141 if (subspace.initialization_length > 0
142 && subspace.file_loc_init_value > location)
144 subspace.file_loc_init_value += offset;
145 check_lseek (file, -subspace_size, 1);
146 if (write (file, &subspace, subspace_size) != subspace_size)
147 unexec_error ("Can't update subspace record");
151 /* Do for each initialization pointer record */
152 /* (I don't think it applies to executable files, only relocatables) */
153 #undef update
156 /* Read in the header records from an a.out file. */
158 static void
159 read_header (int file, struct header *hdr, struct som_exec_auxhdr *auxhdr)
162 /* Read the header in */
163 check_lseek (file, 0, 0);
164 if (read (file, hdr, sizeof (*hdr)) != sizeof (*hdr))
165 unexec_error ("Couldn't read header from a.out file");
167 if (hdr->a_magic != EXEC_MAGIC && hdr->a_magic != SHARE_MAGIC
168 && hdr->a_magic != DEMAND_MAGIC)
170 fprintf (stderr, "a.out file doesn't have valid magic number\n");
171 exit (1);
174 check_lseek (file, hdr->aux_header_location, 0);
175 if (read (file, auxhdr, sizeof (*auxhdr)) != sizeof (*auxhdr))
176 unexec_error ("Couldn't read auxiliary header from a.out file");
179 /* Write out the header records into an a.out file. */
181 static void
182 write_header (int file, struct header *hdr, struct som_exec_auxhdr *auxhdr)
184 /* Update the checksum */
185 hdr->checksum = calculate_checksum (hdr);
187 /* Write the header back into the a.out file */
188 check_lseek (file, 0, 0);
189 if (write (file, hdr, sizeof (*hdr)) != sizeof (*hdr))
190 unexec_error ("Couldn't write header to a.out file");
191 check_lseek (file, hdr->aux_header_location, 0);
192 if (write (file, auxhdr, sizeof (*auxhdr)) != sizeof (*auxhdr))
193 unexec_error ("Couldn't write auxiliary header to a.out file");
196 /* Calculate the checksum of a SOM header record. */
198 static int
199 calculate_checksum (struct header *hdr)
201 int checksum, i, *ptr;
203 checksum = 0; ptr = (int *) hdr;
205 for (i = 0; i < sizeof (*hdr) / sizeof (int) - 1; i++)
206 checksum ^= ptr[i];
208 return (checksum);
211 /* Copy size bytes from the old file to the new one. */
213 static void
214 copy_file (int old, int new, int size)
216 int len;
217 int buffer[8192]; /* word aligned will be faster */
219 for (; size > 0; size -= len)
221 len = min (size, sizeof (buffer));
222 if (read (old, buffer, len) != len)
223 unexec_error ("Read failure on a.out file");
224 if (write (new, buffer, len) != len)
225 unexec_error ("Write failure in a.out file");
229 /* Copy the rest of the file, up to EOF. */
231 static void
232 copy_rest (int old, int new)
234 int buffer[4096];
235 int len;
237 /* Copy bytes until end of file or error */
238 while ((len = read (old, buffer, sizeof (buffer))) > 0)
239 if (write (new, buffer, len) != len) break;
241 if (len != 0)
242 unexec_error ("Unable to copy the rest of the file");
245 #ifdef DEBUG
246 static void
247 display_header (struct header *hdr, struct som_exec_auxhdr *auxhdr)
249 /* Display the header information (debug) */
250 printf ("\n\nFILE HEADER\n");
251 printf ("magic number %d \n", hdr->a_magic);
252 printf ("text loc %.8x size %d \n", auxhdr->exec_tmem, auxhdr->exec_tsize);
253 printf ("data loc %.8x size %d \n", auxhdr->exec_dmem, auxhdr->exec_dsize);
254 printf ("entry %x \n", auxhdr->exec_entry);
255 printf ("Bss segment size %u\n", auxhdr->exec_bsize);
256 printf ("\n");
257 printf ("data file loc %d size %d\n",
258 auxhdr->exec_dfile, auxhdr->exec_dsize);
259 printf ("som_length %d\n", hdr->som_length);
260 printf ("unloadable sploc %d size %d\n",
261 hdr->unloadable_sp_location, hdr->unloadable_sp_size);
263 #endif /* DEBUG */
266 /* Create a new a.out file, same as old but with current data space */
267 void
268 unexec (const char *new_name, /* name of the new a.out file to be created */
269 const char *old_name) /* name of the old a.out file */
271 int old, new;
272 int old_size, new_size;
273 struct header hdr;
274 struct som_exec_auxhdr auxhdr;
275 long i;
277 /* For the greatest flexibility, should create a temporary file in
278 the same directory as the new file. When everything is complete,
279 rename the temp file to the new name.
280 This way, a program could update its own a.out file even while
281 it is still executing. If problems occur, everything is still
282 intact. NOT implemented. */
284 /* Open the input and output a.out files. */
285 old = emacs_open (old_name, O_RDONLY, 0);
286 if (old < 0)
287 unexec_error (old_name);
288 new = emacs_open (new_name, O_CREAT | O_RDWR | O_TRUNC, 0777);
289 if (new < 0)
290 unexec_error (new_name);
292 /* Read the old headers. */
293 read_header (old, &hdr, &auxhdr);
295 brk_on_dump = (long) sbrk (0);
297 /* Decide how large the new and old data areas are. */
298 old_size = auxhdr.exec_dsize;
299 /* I suspect these two statements are separate
300 to avoid a compiler bug in hpux version 8. */
301 i = (long) sbrk (0);
302 new_size = i - auxhdr.exec_dmem;
304 /* Copy the old file to the new, up to the data space. */
305 check_lseek (old, 0, 0);
306 copy_file (old, new, auxhdr.exec_dfile);
308 /* Skip the old data segment and write a new one. */
309 check_lseek (old, old_size, 1);
310 save_data_space (new, &hdr, &auxhdr, new_size);
312 /* Copy the rest of the file. */
313 copy_rest (old, new);
315 /* Update file pointers since we probably changed size of data area. */
316 update_file_ptrs (new, &hdr, &auxhdr, auxhdr.exec_dfile, new_size-old_size);
318 /* Save the modified header. */
319 write_header (new, &hdr, &auxhdr);
321 /* Close the binary file. */
322 emacs_close (old);
323 emacs_close (new);