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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>
430
+ − 55 #include <stdlib.h>
428
+ − 56 #include <stdio.h>
+ − 57 #include <fcntl.h>
+ − 58 #include <errno.h>
+ − 59
+ − 60 #include <a.out.h>
442
+ − 61 #include "lisp.h"
428
+ − 62
+ − 63 /*
+ − 64 * Minor modification to enable dumping with shared libraries added by
+ − 65 * Dipankar Gupta (dg@hplb.hpl.hp.com). I studied Oliver Laumann's
+ − 66 * more elaborate dynamic loading scheme in ELK while implementing
+ − 67 * this, but don't use any of his machinery.
+ − 68 *
+ − 69 * Stores the BRK value at dump time, and uses the RUN_TIME_REMAP hook
+ − 70 * to break back to the stored value when the dumped executable is restarted.
+ − 71 *
+ − 72 * CAVEATS (addenda):
+ − 73 * 1. Text area of the shlibs are not stored. Thus, if a shared library is
+ − 74 * replaced between the time of dump and execution, all bets are off.
+ − 75 *
+ − 76 * 2. Assumes that the data and bss area are adjacent, which is true of the
+ − 77 * current VM implementation.
+ − 78 *
+ − 79 * 3. Any setup that defines HPUX_USE_SHLIBS *must* also define
+ − 80 * RUN_TIME_REMAP.
+ − 81 */
+ − 82
+ − 83 #ifdef HPUX_USE_SHLIBS
+ − 84 #include <dl.h> /* User-space dynamic loader entry points */
442
+ − 85 static void Save_Shared_Data (void);
+ − 86 static void Restore_Shared_Data (void);
428
+ − 87 #endif
+ − 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
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+ − 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 uintptr_t new_end_of_text, /* ptr to new edata/etext; NOT USED YET */
+ − 105 uintptr_t dummy1, uintptr_t dummy2) /* not used by emacs */
428
+ − 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 {
442
+ − 293 len = size < sizeof (buffer) ? size : sizeof (buffer);
+ − 294 if (read (old, buffer, len) != len)
+ − 295 {
+ − 296 perror ("Read failure on a.out file");
+ − 297 exit (1);
+ − 298 }
+ − 299 if (write (new, buffer, len) != len)
+ − 300 {
+ − 301 perror ("Write failure in a.out file");
+ − 302 exit (1);
+ − 303 }
428
+ − 304 }
+ − 305 }
+ − 306
+ − 307 /* Copy the rest of the file, up to EOF. */
+ − 308 void
+ − 309 copy_rest (int old, int new)
+ − 310 {
+ − 311 int buffer[4096];
+ − 312 int len;
+ − 313
+ − 314 /* Copy bytes until end of file or error */
+ − 315 while ( (len = read(old, buffer, sizeof(buffer))) > 0)
+ − 316 if (write(new, buffer, len) != len) break;
+ − 317
+ − 318 if (len != 0)
+ − 319 { perror("Unable to copy the rest of the file"); exit(1); }
+ − 320 }
+ − 321
+ − 322 #ifdef DEBUG
+ − 323 display_header(struct header *hdr, struct som_exec_auxhdr *auxhdr)
+ − 324 {
+ − 325 /* Display the header information (debug) */
+ − 326 printf("\n\nFILE HEADER\n");
+ − 327 printf("magic number %d \n", hdr->a_magic);
+ − 328 printf("text loc %.8x size %d \n", auxhdr->exec_tmem, auxhdr->exec_tsize);
+ − 329 printf("data loc %.8x size %d \n", auxhdr->exec_dmem, auxhdr->exec_dsize);
+ − 330 printf("entry %x \n", auxhdr->exec_entry);
+ − 331 printf("Bss segment size %u\n", auxhdr->exec_bsize);
+ − 332 printf("\n");
+ − 333 printf("data file loc %d size %d\n",
+ − 334 auxhdr->exec_dfile, auxhdr->exec_dsize);
+ − 335 printf("som_length %d\n", hdr->som_length);
+ − 336 printf("unloadable sploc %d size %d\n",
+ − 337 hdr->unloadable_sp_location, hdr->unloadable_sp_size);
+ − 338 }
+ − 339 #endif /* DEBUG */
+ − 340
+ − 341 #ifdef HPUX_USE_SHLIBS
+ − 342 /* Added machinery for shared libs... see comments at the beginning of this file. */
+ − 343
+ − 344 void *Brk_On_Dump = 0; /* Brk value to restore... stored as a global */
+ − 345
442
+ − 346 static void
+ − 347 Save_Shared_Data (void)
+ − 348 {
+ − 349 Brk_On_Dump = sbrk (0);
428
+ − 350 }
+ − 351
442
+ − 352 static void
+ − 353 Restore_Shared_Data (void)
+ − 354 {
+ − 355 brk (Brk_On_Dump);
428
+ − 356 }
+ − 357
+ − 358 /* run_time_remap is the magic called by startup code in the dumped executable
442
+ − 359 if RUN_TIME_REMAP is set. */
+ − 360 int
+ − 361 run_time_remap (char *dummy)
+ − 362 {
+ − 363 Restore_Shared_Data ();
+ − 364 return 0;
+ − 365 }
428
+ − 366 #endif /* HPUX_USE_SHLIBS */
