src/unexhp9k800.c

   1 /* Unexec for HP 9000 Series 800 machines.
   2
   3   This file is in the public domain.
   4
   5   Author: John V. Morris
   6
   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.)
  11 */
  12
  13 /*
  14    Bob Desinger <hpsemc!bd@hplabs.hp.com>
  15
  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.
  22
  23
  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.
  28
  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.
  32
  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.
  35
  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.
  41
  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.
  46
  47   void _sigreturn ();
  48   ...
  49   sigsetreturn (_sigreturn);
  50 */
  51 \f
  52 #ifdef emacs
  53 #include <config.h>
  54 #endif
  55
  56 #include <stdio.h>
  57 #include <fcntl.h>
  58 #include <errno.h>
  59
  60 #include <a.out.h>
  61
  62 #ifdef HPUX_USE_SHLIBS
  63 #include <dl.h>
  64 #endif
  65
  66 /* brk value to restore, stored as a global.
  67    This is really used only if we used shared libraries.  */
  68 static long brk_on_dump = 0;
  69
  70 /* Called from main, if we use shared libraries.  */
  71 int
  72 run_time_remap (ignored)
  73      char *ignored;
  74 {
  75   brk ((char *) brk_on_dump);
  76 }
  77
  78 #undef roundup
  79 #define roundup(x,n) (((x) + ((n) - 1)) & ~((n) - 1))  /* n is power of 2 */
  80 #define min(x,y)  (((x) < (y)) ? (x) : (y))
  81
  82
  83 /* Create a new a.out file, same as old but with current data space */
  84
  85 unexec (new_name, old_name, new_end_of_text, dummy1, dummy2)
  86      char new_name[];           /* name of the new a.out file to be created */
  87      char old_name[];           /* name of the old a.out file */
  88      char *new_end_of_text;     /* ptr to new edata/etext; NOT USED YET */
  89      int dummy1, dummy2;        /* not used by emacs */
  90 {
  91   int old, new;
  92   int old_size, new_size;
  93   struct header hdr;
  94   struct som_exec_auxhdr auxhdr;
  95   long i;
  96
  97   /* For the greatest flexibility, should create a temporary file in
  98      the same directory as the new file.  When everything is complete,
  99      rename the temp file to the new name.
 100      This way, a program could update its own a.out file even while
 101      it is still executing.  If problems occur, everything is still
 102      intact.  NOT implemented.  */
 103
 104   /* Open the input and output a.out files */
 105   old = open (old_name, O_RDONLY);
 106   if (old < 0)
 107     { perror (old_name); exit (1); }
 108   new = open (new_name, O_CREAT|O_RDWR|O_TRUNC, 0777);
 109   if (new < 0)
 110     { perror (new_name); exit (1); }
 111
 112   /* Read the old headers */
 113   read_header (old, &hdr, &auxhdr);
 114
 115   brk_on_dump = (long) sbrk (0);
 116
 117   /* Decide how large the new and old data areas are */
 118   old_size = auxhdr.exec_dsize;
 119   /* I suspect these two statements are separate
 120      to avoid a compiler bug in hpux version 8.  */
 121   i = (long) sbrk (0);
 122   new_size = i - auxhdr.exec_dmem;
 123
 124   /* Copy the old file to the new, up to the data space */
 125   lseek (old, 0, 0);
 126   copy_file (old, new, auxhdr.exec_dfile);
 127
 128   /* Skip the old data segment and write a new one */
 129   lseek (old, old_size, 1);
 130   save_data_space (new, &hdr, &auxhdr, new_size);
 131
 132   /* Copy the rest of the file */
 133   copy_rest (old, new);
 134
 135   /* Update file pointers since we probably changed size of data area */
 136   update_file_ptrs (new, &hdr, &auxhdr, auxhdr.exec_dfile, new_size-old_size);
 137
 138   /* Save the modified header */
 139   write_header (new, &hdr, &auxhdr);
 140
 141   /* Close the binary file */
 142   close (old);
 143   close (new);
 144   return 0;
 145 }
 146
 147 /* Save current data space in the file, update header.  */
 148
 149 save_data_space (file, hdr, auxhdr, size)
 150      int file;
 151      struct header *hdr;
 152      struct som_exec_auxhdr *auxhdr;
 153      int size;
 154 {
 155   /* Write the entire data space out to the file */
 156   if (write (file, auxhdr->exec_dmem, size) != size)
 157     { perror ("Can't save new data space"); exit (1); }
 158
 159   /* Update the header to reflect the new data size */
 160   auxhdr->exec_dsize = size;
 161   auxhdr->exec_bsize = 0;
 162 }
 163
 164 /* Update the values of file pointers when something is inserted.  */
 165
 166 update_file_ptrs (file, hdr, auxhdr, location, offset)
 167      int file;
 168      struct header *hdr;
 169      struct som_exec_auxhdr *auxhdr;
 170      unsigned int location;
 171      int offset;
 172 {
 173   struct subspace_dictionary_record subspace;
 174   int i;
 175
 176   /* Increase the overall size of the module */
 177   hdr->som_length += offset;
 178
 179   /* Update the various file pointers in the header */
 180 #define update(ptr) if (ptr > location) ptr = ptr + offset
 181   update (hdr->aux_header_location);
 182   update (hdr->space_strings_location);
 183   update (hdr->init_array_location);
 184   update (hdr->compiler_location);
 185   update (hdr->symbol_location);
 186   update (hdr->fixup_request_location);
 187   update (hdr->symbol_strings_location);
 188   update (hdr->unloadable_sp_location);
 189   update (auxhdr->exec_tfile);
 190   update (auxhdr->exec_dfile);
 191
 192   /* Do for each subspace dictionary entry */
 193   lseek (file, hdr->subspace_location, 0);
 194   for (i = 0; i < hdr->subspace_total; i++)
 195     {
 196       if (read (file, &subspace, sizeof (subspace)) != sizeof (subspace))
 197         { perror ("Can't read subspace record"); exit (1); }
 198
 199       /* If subspace has a file location, update it */
 200       if (subspace.initialization_length > 0
 201           && subspace.file_loc_init_value > location)
 202         {
 203           subspace.file_loc_init_value += offset;
 204           lseek (file, -sizeof (subspace), 1);
 205           if (write (file, &subspace, sizeof (subspace)) != sizeof (subspace))
 206             { perror ("Can't update subspace record"); exit (1); }
 207         }
 208     }
 209
 210   /* Do for each initialization pointer record */
 211   /* (I don't think it applies to executable files, only relocatables) */
 212 #undef update
 213 }
 214
 215 /* Read in the header records from an a.out file.  */
 216
 217 read_header (file, hdr, auxhdr)
 218      int file;
 219      struct header *hdr;
 220      struct som_exec_auxhdr *auxhdr;
 221 {
 222
 223   /* Read the header in */
 224   lseek (file, 0, 0);
 225   if (read (file, hdr, sizeof (*hdr)) != sizeof (*hdr))
 226     { perror ("Couldn't read header from a.out file"); exit (1); }
 227
 228   if (hdr->a_magic != EXEC_MAGIC && hdr->a_magic != SHARE_MAGIC
 229       &&  hdr->a_magic != DEMAND_MAGIC)
 230     {
 231       fprintf (stderr, "a.out file doesn't have legal magic number\n");
 232       exit (1);
 233     }
 234
 235   lseek (file, hdr->aux_header_location, 0);
 236   if (read (file, auxhdr, sizeof (*auxhdr)) != sizeof (*auxhdr))
 237     {
 238       perror ("Couldn't read auxiliary header from a.out file");
 239       exit (1);
 240     }
 241 }
 242
 243 /* Write out the header records into an a.out file.  */
 244
 245 write_header (file, hdr, auxhdr)
 246      int file;
 247      struct header *hdr;
 248      struct som_exec_auxhdr *auxhdr;
 249 {
 250   /* Update the checksum */
 251   hdr->checksum = calculate_checksum (hdr);
 252
 253   /* Write the header back into the a.out file */
 254   lseek (file, 0, 0);
 255   if (write (file, hdr, sizeof (*hdr)) != sizeof (*hdr))
 256     { perror ("Couldn't write header to a.out file"); exit (1); }
 257   lseek (file, hdr->aux_header_location, 0);
 258   if (write (file, auxhdr, sizeof (*auxhdr)) != sizeof (*auxhdr))
 259     { perror ("Couldn't write auxiliary header to a.out file"); exit (1); }
 260 }
 261
 262 /* Calculate the checksum of a SOM header record. */
 263
 264 calculate_checksum (hdr)
 265      struct header *hdr;
 266 {
 267   int checksum, i, *ptr;
 268
 269   checksum = 0;  ptr = (int *) hdr;
 270
 271   for (i = 0; i < sizeof (*hdr) / sizeof (int) - 1; i++)
 272     checksum ^= ptr[i];
 273
 274   return (checksum);
 275 }
 276
 277 /* Copy size bytes from the old file to the new one.  */
 278
 279 copy_file (old, new, size)
 280      int new, old;
 281      int size;
 282 {
 283   int len;
 284   int buffer[8192];  /* word aligned will be faster */
 285
 286   for (; size > 0; size -= len)
 287     {
 288       len = min (size, sizeof (buffer));
 289       if (read (old, buffer, len) != len)
 290         { perror ("Read failure on a.out file"); exit (1); }
 291       if (write (new, buffer, len) != len)
 292         { perror ("Write failure in a.out file"); exit (1); }
 293     }
 294 }
 295
 296 /* Copy the rest of the file, up to EOF.  */
 297
 298 copy_rest (old, new)
 299      int new, old;
 300 {
 301   int buffer[4096];
 302   int len;
 303
 304   /* Copy bytes until end of file or error */
 305   while ((len = read (old, buffer, sizeof (buffer))) > 0)
 306     if (write (new, buffer, len) != len) break;
 307
 308   if (len != 0)
 309     { perror ("Unable to copy the rest of the file"); exit (1); }
 310 }
 311
 312 #ifdef  DEBUG
 313 display_header (hdr, auxhdr)
 314      struct header *hdr;
 315      struct som_exec_auxhdr *auxhdr;
 316 {
 317   /* Display the header information (debug) */
 318   printf ("\n\nFILE HEADER\n");
 319   printf ("magic number %d \n", hdr->a_magic);
 320   printf ("text loc %.8x   size %d \n", auxhdr->exec_tmem, auxhdr->exec_tsize);
 321   printf ("data loc %.8x   size %d \n", auxhdr->exec_dmem, auxhdr->exec_dsize);
 322   printf ("entry     %x \n",   auxhdr->exec_entry);
 323   printf ("Bss  segment size %u\n", auxhdr->exec_bsize);
 324   printf ("\n");
 325   printf ("data file loc %d    size %d\n",
 326           auxhdr->exec_dfile, auxhdr->exec_dsize);
 327   printf ("som_length %d\n", hdr->som_length);
 328   printf ("unloadable sploc %d    size %d\n",
 329           hdr->unloadable_sp_location, hdr->unloadable_sp_size);
 330 }
 331 #endif /* DEBUG */
 332
 333 /* arch-tag: d55a09ac-9427-4ec4-8496-cb9d7710774f
 334    (do not change this comment) */