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[emacs.git] / src / unexhp9k800.c
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1 /* Unexec for HP 9000 Series 800 machines.
2 Bob Desinger <hpsemc!bd@hplabs.hp.com>
4 Note that the GNU project considers support for HP operation a
5 peripheral activity which should not be allowed to divert effort
6 from development of the GNU system. Changes in this code will be
7 installed when users send them in, but aside from that we don't
8 plan to think about it, or about whether other Emacs maintenance
9 might break it.
12 Unexec creates a copy of the old a.out file, and replaces the old data
13 area with the current data area. When the new file is executed, the
14 process will see the same data structures and data values that the
15 original process had when unexec was called.
17 Unlike other versions of unexec, this one copies symbol table and
18 debug information to the new a.out file. Thus, the new a.out file
19 may be debugged with symbolic debuggers.
21 If you fix any bugs in this, I'd like to incorporate your fixes.
22 Send them to uunet!hpda!hpsemc!jmorris or jmorris%hpsemc@hplabs.HP.COM.
24 CAVEATS:
25 This routine saves the current value of all static and external
26 variables. This means that any data structure that needs to be
27 initialized must be explicitly reset. Variables will not have their
28 expected default values.
30 Unfortunately, the HP-UX signal handler has internal initialization
31 flags which are not explicitly reset. Thus, for signals to work in
32 conjunction with this routine, the following code must executed when
33 the new process starts up.
35 void _sigreturn ();
36 ...
37 sigsetreturn (_sigreturn);
40 #ifdef emacs
41 #include <config.h>
42 #endif
44 #include <stdio.h>
45 #include <fcntl.h>
46 #include <errno.h>
48 #include <a.out.h>
50 #ifdef HPUX_USE_SHLIBS
51 #include <dl.h>
52 #endif
54 /* brk value to restore, stored as a global.
55 This is really used only if we used shared libraries. */
56 static long brk_on_dump = 0;
58 /* Called from main, if we use shared libraries. */
59 int
60 run_time_remap (ignored)
61 char *ignored;
63 brk ((char *) brk_on_dump);
66 #undef roundup
67 #define roundup(x,n) (((x) + ((n) - 1)) & ~((n) - 1)) /* n is power of 2 */
68 #define min(x,y) (((x) < (y)) ? (x) : (y))
71 /* Create a new a.out file, same as old but with current data space */
73 unexec (new_name, old_name, new_end_of_text, dummy1, dummy2)
74 char new_name[]; /* name of the new a.out file to be created */
75 char old_name[]; /* name of the old a.out file */
76 char *new_end_of_text; /* ptr to new edata/etext; NOT USED YET */
77 int dummy1, dummy2; /* not used by emacs */
79 int old, new;
80 int old_size, new_size;
81 struct header hdr;
82 struct som_exec_auxhdr auxhdr;
83 long i;
85 /* For the greatest flexibility, should create a temporary file in
86 the same directory as the new file. When everything is complete,
87 rename the temp file to the new name.
88 This way, a program could update its own a.out file even while
89 it is still executing. If problems occur, everything is still
90 intact. NOT implemented. */
92 /* Open the input and output a.out files */
93 old = open (old_name, O_RDONLY);
94 if (old < 0)
95 { perror (old_name); exit (1); }
96 new = open (new_name, O_CREAT|O_RDWR|O_TRUNC, 0777);
97 if (new < 0)
98 { perror (new_name); exit (1); }
100 /* Read the old headers */
101 read_header (old, &hdr, &auxhdr);
103 brk_on_dump = (long) sbrk (0);
105 /* Decide how large the new and old data areas are */
106 old_size = auxhdr.exec_dsize;
107 /* I suspect these two statements are separate
108 to avoid a compiler bug in hpux version 8. */
109 i = (long) sbrk (0);
110 new_size = i - auxhdr.exec_dmem;
112 /* Copy the old file to the new, up to the data space */
113 lseek (old, 0, 0);
114 copy_file (old, new, auxhdr.exec_dfile);
116 /* Skip the old data segment and write a new one */
117 lseek (old, old_size, 1);
118 save_data_space (new, &hdr, &auxhdr, new_size);
120 /* Copy the rest of the file */
121 copy_rest (old, new);
123 /* Update file pointers since we probably changed size of data area */
124 update_file_ptrs (new, &hdr, &auxhdr, auxhdr.exec_dfile, new_size-old_size);
126 /* Save the modified header */
127 write_header (new, &hdr, &auxhdr);
129 /* Close the binary file */
130 close (old);
131 close (new);
132 return 0;
135 /* Save current data space in the file, update header. */
137 save_data_space (file, hdr, auxhdr, size)
138 int file;
139 struct header *hdr;
140 struct som_exec_auxhdr *auxhdr;
141 int size;
143 /* Write the entire data space out to the file */
144 if (write (file, auxhdr->exec_dmem, size) != size)
145 { perror ("Can't save new data space"); exit (1); }
147 /* Update the header to reflect the new data size */
148 auxhdr->exec_dsize = size;
149 auxhdr->exec_bsize = 0;
152 /* Update the values of file pointers when something is inserted. */
154 update_file_ptrs (file, hdr, auxhdr, location, offset)
155 int file;
156 struct header *hdr;
157 struct som_exec_auxhdr *auxhdr;
158 unsigned int location;
159 int offset;
161 struct subspace_dictionary_record subspace;
162 int i;
164 /* Increase the overall size of the module */
165 hdr->som_length += offset;
167 /* Update the various file pointers in the header */
168 #define update(ptr) if (ptr > location) ptr = ptr + offset
169 update (hdr->aux_header_location);
170 update (hdr->space_strings_location);
171 update (hdr->init_array_location);
172 update (hdr->compiler_location);
173 update (hdr->symbol_location);
174 update (hdr->fixup_request_location);
175 update (hdr->symbol_strings_location);
176 update (hdr->unloadable_sp_location);
177 update (auxhdr->exec_tfile);
178 update (auxhdr->exec_dfile);
180 /* Do for each subspace dictionary entry */
181 lseek (file, hdr->subspace_location, 0);
182 for (i = 0; i < hdr->subspace_total; i++)
184 if (read (file, &subspace, sizeof (subspace)) != sizeof (subspace))
185 { perror ("Can't read subspace record"); exit (1); }
187 /* If subspace has a file location, update it */
188 if (subspace.initialization_length > 0
189 && subspace.file_loc_init_value > location)
191 subspace.file_loc_init_value += offset;
192 lseek (file, -sizeof (subspace), 1);
193 if (write (file, &subspace, sizeof (subspace)) != sizeof (subspace))
194 { perror ("Can't update subspace record"); exit (1); }
198 /* Do for each initialization pointer record */
199 /* (I don't think it applies to executable files, only relocatables) */
200 #undef update
203 /* Read in the header records from an a.out file. */
205 read_header (file, hdr, auxhdr)
206 int file;
207 struct header *hdr;
208 struct som_exec_auxhdr *auxhdr;
211 /* Read the header in */
212 lseek (file, 0, 0);
213 if (read (file, hdr, sizeof (*hdr)) != sizeof (*hdr))
214 { perror ("Couldn't read header from a.out file"); exit (1); }
216 if (hdr->a_magic != EXEC_MAGIC && hdr->a_magic != SHARE_MAGIC
217 && hdr->a_magic != DEMAND_MAGIC)
219 fprintf (stderr, "a.out file doesn't have legal magic number\n");
220 exit (1);
223 lseek (file, hdr->aux_header_location, 0);
224 if (read (file, auxhdr, sizeof (*auxhdr)) != sizeof (*auxhdr))
226 perror ("Couldn't read auxiliary header from a.out file");
227 exit (1);
231 /* Write out the header records into an a.out file. */
233 write_header (file, hdr, auxhdr)
234 int file;
235 struct header *hdr;
236 struct som_exec_auxhdr *auxhdr;
238 /* Update the checksum */
239 hdr->checksum = calculate_checksum (hdr);
241 /* Write the header back into the a.out file */
242 lseek (file, 0, 0);
243 if (write (file, hdr, sizeof (*hdr)) != sizeof (*hdr))
244 { perror ("Couldn't write header to a.out file"); exit (1); }
245 lseek (file, hdr->aux_header_location, 0);
246 if (write (file, auxhdr, sizeof (*auxhdr)) != sizeof (*auxhdr))
247 { perror ("Couldn't write auxiliary header to a.out file"); exit (1); }
250 /* Calculate the checksum of a SOM header record. */
252 calculate_checksum (hdr)
253 struct header *hdr;
255 int checksum, i, *ptr;
257 checksum = 0; ptr = (int *) hdr;
259 for (i = 0; i < sizeof (*hdr) / sizeof (int) - 1; i++)
260 checksum ^= ptr[i];
262 return (checksum);
265 /* Copy size bytes from the old file to the new one. */
267 copy_file (old, new, size)
268 int new, old;
269 int size;
271 int len;
272 int buffer[8192]; /* word aligned will be faster */
274 for (; size > 0; size -= len)
276 len = min (size, sizeof (buffer));
277 if (read (old, buffer, len) != len)
278 { perror ("Read failure on a.out file"); exit (1); }
279 if (write (new, buffer, len) != len)
280 { perror ("Write failure in a.out file"); exit (1); }
284 /* Copy the rest of the file, up to EOF. */
286 copy_rest (old, new)
287 int new, old;
289 int buffer[4096];
290 int len;
292 /* Copy bytes until end of file or error */
293 while ((len = read (old, buffer, sizeof (buffer))) > 0)
294 if (write (new, buffer, len) != len) break;
296 if (len != 0)
297 { perror ("Unable to copy the rest of the file"); exit (1); }
300 #ifdef DEBUG
301 display_header (hdr, auxhdr)
302 struct header *hdr;
303 struct som_exec_auxhdr *auxhdr;
305 /* Display the header information (debug) */
306 printf ("\n\nFILE HEADER\n");
307 printf ("magic number %d \n", hdr->a_magic);
308 printf ("text loc %.8x size %d \n", auxhdr->exec_tmem, auxhdr->exec_tsize);
309 printf ("data loc %.8x size %d \n", auxhdr->exec_dmem, auxhdr->exec_dsize);
310 printf ("entry %x \n", auxhdr->exec_entry);
311 printf ("Bss segment size %u\n", auxhdr->exec_bsize);
312 printf ("\n");
313 printf ("data file loc %d size %d\n",
314 auxhdr->exec_dfile, auxhdr->exec_dsize);
315 printf ("som_length %d\n", hdr->som_length);
316 printf ("unloadable sploc %d size %d\n",
317 hdr->unloadable_sp_location, hdr->unloadable_sp_size);
319 #endif /* DEBUG */