gdb/objfiles.c

   1 /* GDB routines for manipulating objfiles.
   2    Copyright 1992 Free Software Foundation, Inc.
   3    Contributed by Cygnus Support, using pieces from other GDB modules.
   4
   5 This file is part of GDB.
   6
   7 This program is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2 of the License, or
  10 (at your option) any later version.
  11
  12 This program is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with this program; if not, write to the Free Software
  19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 /* This file contains support routines for creating, manipulating, and
  22    destroying objfile structures. */
  23
  24 #include "defs.h"
  25 #include "bfd.h"                /* Binary File Description */
  26 #include "symtab.h"
  27 #include "symfile.h"
  28 #include "objfiles.h"
  29
  30 #include <sys/types.h>
  31 #include <sys/stat.h>
  32 #include <fcntl.h>
  33 #include <obstack.h>
  34
  35 /* Prototypes for local functions */
  36
  37 static int
  38 open_mapped_file PARAMS ((char *filename, long mtime, int mapped));
  39
  40 static CORE_ADDR
  41 map_to_address PARAMS ((void));
  42
  43 /* Externally visible variables that are owned by this module.
  44    See declarations in objfile.h for more info. */
  45
  46 struct objfile *object_files;           /* Linked list of all objfiles */
  47 struct objfile *current_objfile;        /* For symbol file being read in */
  48 struct objfile *symfile_objfile;        /* Main symbol table loaded from */
  49
  50 int mapped_symbol_files;                /* Try to use mapped symbol files */
  51
  52 /* Given a pointer to an initialized bfd (ABFD) and a flag that indicates
  53    whether or not an objfile is to be mapped (MAPPED), allocate a new objfile
  54    struct, fill it in as best we can, link it into the list of all known
  55    objfiles, and return a pointer to the new objfile struct. */
  56
  57 struct objfile *
  58 allocate_objfile (abfd, mapped)
  59      bfd *abfd;
  60      int mapped;
  61 {
  62   struct objfile *objfile = NULL;
  63   int fd;
  64   void *md;
  65   CORE_ADDR mapto;
  66
  67   mapped |= mapped_symbol_files;
  68
  69 #if !defined(NO_MMALLOC) && defined(HAVE_MMAP)
  70
  71   /* If we can support mapped symbol files, try to open/reopen the mapped file
  72      that corresponds to the file from which we wish to read symbols.  If the
  73      objfile is to be mapped, we must malloc the structure itself using the
  74      mmap version, and arrange that all memory allocation for the objfile uses
  75      the mmap routines.  If we are reusing an existing mapped file, from which
  76      we get our objfile pointer, we have to make sure that we update the
  77      pointers to the alloc/free functions in the obstack, in case these
  78      functions have moved within the current gdb. */
  79
  80   fd = open_mapped_file (bfd_get_filename (abfd), bfd_get_mtime (abfd),
  81                          mapped);
  82   if (fd >= 0)
  83     {
  84       if (((mapto = map_to_address ()) == 0) ||
  85           ((md = mmalloc_attach (fd, (void *) mapto)) == NULL))
  86         {
  87           close (fd);
  88         }
  89       else if ((objfile = (struct objfile *) mmalloc_getkey (md, 0)) != NULL)
  90         {
  91           /* Update memory corruption handler function addresses. */
  92           init_malloc (md);
  93           objfile -> md = md;
  94           /* Update pointers to functions to *our* copies */
  95           obstack_chunkfun (&objfile -> psymbol_obstack, xmmalloc);
  96           obstack_freefun (&objfile -> psymbol_obstack, mfree);
  97           obstack_chunkfun (&objfile -> symbol_obstack, xmmalloc);
  98           obstack_freefun (&objfile -> symbol_obstack, mfree);
  99           obstack_chunkfun (&objfile -> type_obstack, xmmalloc);
 100           obstack_freefun (&objfile -> type_obstack, mfree);
 101         }
 102       else
 103         {
 104           /* Set up to detect internal memory corruption.  MUST be done before
 105              the first malloc.  See comments in init_malloc() and mmcheck(). */
 106           init_malloc (md);
 107           objfile = (struct objfile *) xmmalloc (md, sizeof (struct objfile));
 108           (void) memset (objfile, 0, sizeof (struct objfile));
 109           objfile -> md = md;
 110           objfile -> flags |= OBJF_MAPPED;
 111           mmalloc_setkey (objfile -> md, 0, objfile);
 112           obstack_full_begin (&objfile -> psymbol_obstack, 0, 0,
 113                               xmmalloc, mfree, objfile -> md,
 114                               OBSTACK_MMALLOC_LIKE);
 115           obstack_full_begin (&objfile -> symbol_obstack, 0, 0,
 116                               xmmalloc, mfree, objfile -> md,
 117                               OBSTACK_MMALLOC_LIKE);
 118           obstack_full_begin (&objfile -> type_obstack, 0, 0,
 119                               xmmalloc, mfree, objfile -> md,
 120                               OBSTACK_MMALLOC_LIKE);
 121         }
 122     }
 123
 124   if (mapped && (objfile == NULL))
 125     {
 126       warning ("symbol table for '%s' will not be mapped",
 127                bfd_get_filename (abfd));
 128     }
 129
 130 #else   /* defined(NO_MMALLOC) || !defined(HAVE_MMAP) */
 131
 132   if (mapped)
 133     {
 134       warning ("this version of gdb does not support mapped symbol tables.");
 135
 136       /* Turn off the global flag so we don't try to do mapped symbol tables
 137          any more, which shuts up gdb unless the user specifically gives the
 138          "mapped" keyword again. */
 139
 140       mapped_symbol_files = 0;
 141     }
 142
 143 #endif  /* !defined(NO_MMALLOC) && defined(HAVE_MMAP) */
 144
 145   /* If we don't support mapped symbol files, didn't ask for the file to be
 146      mapped, or failed to open the mapped file for some reason, then revert
 147      back to an unmapped objfile. */
 148
 149   if (objfile == NULL)
 150     {
 151       objfile = (struct objfile *) xmalloc (sizeof (struct objfile));
 152       (void) memset (objfile, 0, sizeof (struct objfile));
 153       objfile -> md = NULL;
 154       obstack_full_begin (&objfile -> psymbol_obstack, 0, 0, xmalloc, free,
 155                           (void *) 0, 0);
 156       obstack_full_begin (&objfile -> symbol_obstack, 0, 0, xmalloc, free,
 157                           (void *) 0, 0);
 158       obstack_full_begin (&objfile -> type_obstack, 0, 0, xmalloc, free,
 159                           (void *) 0, 0);
 160
 161     }
 162
 163   /* Update the per-objfile information that comes from the bfd, ensuring
 164      that any data that is reference is saved in the per-objfile data
 165      region. */
 166
 167   objfile -> obfd = abfd;
 168   objfile -> name = mstrsave (objfile -> md, bfd_get_filename (abfd));
 169   objfile -> mtime = bfd_get_mtime (abfd);
 170
 171   /* Push this file onto the head of the linked list of other such files. */
 172
 173   objfile -> next = object_files;
 174   object_files = objfile;
 175
 176   return (objfile);
 177 }
 178
 179
 180 /* Destroy an objfile and all the symtabs and psymtabs under it.  Note
 181    that as much as possible is allocated on the symbol_obstack and
 182    psymbol_obstack, so that the memory can be efficiently freed.
 183
 184    Things which we do NOT free because they are not in malloc'd memory
 185    or not in memory specific to the objfile include:
 186
 187         objfile -> sf
 188
 189    */
 190
 191 void
 192 free_objfile (objfile)
 193      struct objfile *objfile;
 194 {
 195   struct objfile *ofp;
 196
 197   if (objfile -> sf != NULL)
 198     {
 199       (*objfile -> sf -> sym_finish) (objfile);
 200     }
 201   if (objfile -> name != NULL)
 202     {
 203       mfree (objfile -> md, objfile -> name);
 204     }
 205   if (objfile -> obfd != NULL)
 206     {
 207       bfd_close (objfile -> obfd);
 208     }
 209
 210   /* Remove it from the chain of all objfiles.  */
 211
 212   if (object_files == objfile)
 213     {
 214       object_files = objfile -> next;
 215     }
 216   else
 217     {
 218       for (ofp = object_files; ofp; ofp = ofp -> next)
 219         {
 220           if (ofp -> next == objfile)
 221             {
 222               ofp -> next = objfile -> next;
 223             }
 224         }
 225     }
 226
 227   obstack_free (&objfile -> psymbol_obstack, 0);
 228   obstack_free (&objfile -> symbol_obstack, 0);
 229   obstack_free (&objfile -> type_obstack, 0);
 230
 231 #if 0   /* FIXME!! */
 232
 233   /* Before the symbol table code was redone to make it easier to
 234      selectively load and remove information particular to a specific
 235      linkage unit, gdb used to do these things whenever the monolithic
 236      symbol table was blown away.  How much still needs to be done
 237      is unknown, but we play it safe for now and keep each action until
 238      it is shown to be no longer needed. */
 239
 240   clear_symtab_users_once ();
 241 #if defined (CLEAR_SOLIB)
 242   CLEAR_SOLIB ();
 243 #endif
 244   clear_pc_function_cache ();
 245
 246 #endif
 247
 248   /* The last thing we do is free the objfile struct itself */
 249
 250   mfree (objfile -> md, objfile);
 251 }
 252
 253
 254 /* Free all the object files at once.  */
 255
 256 void
 257 free_all_objfiles ()
 258 {
 259   struct objfile *objfile, *temp;
 260
 261   ALL_OBJFILES_SAFE (objfile, temp)
 262     {
 263       free_objfile (objfile);
 264     }
 265 }
 266
 267 /* Many places in gdb want to test just to see if we have any partial
 268    symbols available.  This function returns zero if none are currently
 269    available, nonzero otherwise. */
 270
 271 int
 272 have_partial_symbols ()
 273 {
 274   struct objfile *ofp;
 275
 276   ALL_OBJFILES (ofp)
 277     {
 278       if (ofp -> psymtabs != NULL)
 279         {
 280           return 1;
 281         }
 282     }
 283   return 0;
 284 }
 285
 286 /* Many places in gdb want to test just to see if we have any full
 287    symbols available.  This function returns zero if none are currently
 288    available, nonzero otherwise. */
 289
 290 int
 291 have_full_symbols ()
 292 {
 293   struct objfile *ofp;
 294
 295   ALL_OBJFILES (ofp)
 296     {
 297       if (ofp -> symtabs != NULL)
 298         {
 299           return 1;
 300         }
 301     }
 302   return 0;
 303 }
 304
 305 /* Many places in gdb want to test just to see if we have any minimal
 306    symbols available.  This function returns zero if none are currently
 307    available, nonzero otherwise. */
 308
 309 int
 310 have_minimal_symbols ()
 311 {
 312   struct objfile *ofp;
 313
 314   ALL_OBJFILES (ofp)
 315     {
 316       if (ofp -> msymbols != NULL)
 317         {
 318           return 1;
 319         }
 320     }
 321   return 0;
 322 }
 323
 324 /* Look for a mapped symbol file that corresponds to FILENAME and is more
 325    recent than MTIME.  If MAPPED is nonzero, the user has asked that gdb
 326    use a mapped symbol file for this file, so create a new one if one does
 327    not currently exist.
 328
 329    If found, then return an open file descriptor for the file, otherwise
 330    return -1.
 331
 332    This routine is responsible for implementing the policy that generates
 333    the name of the mapped symbol file from the name of a file containing
 334    symbols that gdb would like to read. */
 335
 336 static int
 337 open_mapped_file (filename, mtime, mapped)
 338      char *filename;
 339      long mtime;
 340      int mapped;
 341 {
 342   int fd;
 343   char *symfilename;
 344   struct stat sbuf;
 345
 346   /* For now, all we do is look in the local directory for a file with
 347      the name of the base file and an extension of ".syms" */
 348
 349   symfilename = concat ("./", basename (filename), ".syms", (char *) NULL);
 350
 351   /* Check to see if the desired file already exists and is more recent than
 352      the corresponding base file (specified by the passed MTIME parameter).
 353      The open will fail if the file does not already exist. */
 354
 355   if ((fd = open (symfilename, O_RDWR)) >= 0)
 356     {
 357       if (fstat (fd, &sbuf) != 0)
 358         {
 359           close (fd);
 360           perror_with_name (symfilename);
 361         }
 362       else if (sbuf.st_mtime > mtime)
 363         {
 364           return (fd);
 365         }
 366       else
 367         {
 368           close (fd);
 369           fd = -1;
 370         }
 371     }
 372
 373   /* Either the file does not already exist, or the base file has changed
 374      since it was created.  In either case, if the user has specified use of
 375      a mapped file, then create a new mapped file, truncating any existing
 376      one.
 377
 378      In the case where there is an existing file, but it is out of date, and
 379      the user did not specify mapped, the existing file is just silently
 380      ignored.  Perhaps we should warn about this case (FIXME?).
 381
 382      By default the file is rw for everyone, with the user's umask taking
 383      care of turning off the permissions the user wants off. */
 384
 385   if (mapped)
 386     {
 387       fd = open (symfilename, O_RDWR | O_CREAT | O_TRUNC, 0666);
 388     }
 389
 390   return (fd);
 391 }
 392
 393 /* Return the base address at which we would like the next objfile's
 394    mapped data to start.
 395
 396    For now, we use the kludge that the configuration specifies a base
 397    address to which it is safe to map the first mmalloc heap, and an
 398    increment to add to this address for each successive heap.  There are
 399    a lot of issues to deal with here to make this work reasonably, including:
 400
 401      Avoid memory collisions with existing mapped address spaces
 402
 403      Reclaim address spaces when their mmalloc heaps are unmapped
 404
 405      When mmalloc heaps are shared between processes they have to be
 406      mapped at the same addresses in each
 407
 408      Once created, a mmalloc heap that is to be mapped back in must be
 409      mapped at the original address.  I.E. each objfile will expect to
 410      be remapped at it's original address.  This becomes a problem if
 411      the desired address is already in use.
 412
 413      etc, etc, etc.
 414
 415  */
 416
 417
 418 static CORE_ADDR
 419 map_to_address ()
 420 {
 421
 422 #if defined(MMAP_BASE_ADDRESS) && defined (MMAP_INCREMENT)
 423
 424   static CORE_ADDR next = MMAP_BASE_ADDRESS;
 425   CORE_ADDR mapto = next;
 426
 427   next += MMAP_INCREMENT;
 428   return (mapto);
 429
 430 #else
 431
 432   return (0);
 433
 434 #endif
 435
 436 }