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 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. */ 68static long brk_on_dump = 0; 69 70/* Called from main, if we use shared libraries. */ 71int 72run_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 85unexec (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 149save_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 166update_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 217read_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 245write_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 264calculate_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 279copy_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 298copy_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 313display_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) */ 335