gdb/corelow.c

   1 /* Core dump and executable file functions below target vector, for GDB.
   2
   3    Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996,
   4    1997, 1998, 1999, 2000, 2001, 2003, 2004 Free Software Foundation,
   5    Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #include "defs.h"
  25 #include "arch-utils.h"
  26 #include "gdb_string.h"
  27 #include <errno.h>
  28 #include <signal.h>
  29 #include <fcntl.h>
  30 #ifdef HAVE_SYS_FILE_H
  31 #include <sys/file.h>           /* needed for F_OK and friends */
  32 #endif
  33 #include "frame.h"              /* required by inferior.h */
  34 #include "inferior.h"
  35 #include "symtab.h"
  36 #include "command.h"
  37 #include "bfd.h"
  38 #include "target.h"
  39 #include "gdbcore.h"
  40 #include "gdbthread.h"
  41 #include "regcache.h"
  42 #include "regset.h"
  43 #include "symfile.h"
  44 #include "exec.h"
  45 #include "readline/readline.h"
  46 #include "observer.h"
  47 #include "gdb_assert.h"
  48 #include "exceptions.h"
  49
  50 #ifndef O_BINARY
  51 #define O_BINARY 0
  52 #endif
  53
  54 #ifndef O_LARGEFILE
  55 #define O_LARGEFILE 0
  56 #endif
  57
  58 /* List of all available core_fns.  On gdb startup, each core file
  59    register reader calls deprecated_add_core_fns() to register
  60    information on each core format it is prepared to read.  */
  61
  62 static struct core_fns *core_file_fns = NULL;
  63
  64 /* The core_fns for a core file handler that is prepared to read the core
  65    file currently open on core_bfd. */
  66
  67 static struct core_fns *core_vec = NULL;
  68
  69 /* FIXME: kettenis/20031023: Eventually this variable should
  70    disappear.  */
  71
  72 struct gdbarch *core_gdbarch = NULL;
  73
  74 static void core_files_info (struct target_ops *);
  75
  76 #ifdef SOLIB_ADD
  77 static int solib_add_stub (void *);
  78 #endif
  79
  80 static struct core_fns *sniff_core_bfd (bfd *);
  81
  82 static int gdb_check_format (bfd *);
  83
  84 static void core_open (char *, int);
  85
  86 static void core_detach (char *, int);
  87
  88 static void core_close (int);
  89
  90 static void core_close_cleanup (void *ignore);
  91
  92 static void get_core_registers (int);
  93
  94 static void add_to_thread_list (bfd *, asection *, void *);
  95
  96 static int ignore (CORE_ADDR, char *);
  97
  98 static int core_file_thread_alive (ptid_t tid);
  99
 100 static void init_core_ops (void);
 101
 102 void _initialize_corelow (void);
 103
 104 struct target_ops core_ops;
 105
 106 /* Link a new core_fns into the global core_file_fns list.  Called on gdb
 107    startup by the _initialize routine in each core file register reader, to
 108    register information about each format the the reader is prepared to
 109    handle. */
 110
 111 void
 112 deprecated_add_core_fns (struct core_fns *cf)
 113 {
 114   cf->next = core_file_fns;
 115   core_file_fns = cf;
 116 }
 117
 118 /* The default function that core file handlers can use to examine a
 119    core file BFD and decide whether or not to accept the job of
 120    reading the core file. */
 121
 122 int
 123 default_core_sniffer (struct core_fns *our_fns, bfd *abfd)
 124 {
 125   int result;
 126
 127   result = (bfd_get_flavour (abfd) == our_fns -> core_flavour);
 128   return (result);
 129 }
 130
 131 /* Walk through the list of core functions to find a set that can
 132    handle the core file open on ABFD.  Default to the first one in the
 133    list if nothing matches.  Returns pointer to set that is
 134    selected. */
 135
 136 static struct core_fns *
 137 sniff_core_bfd (bfd *abfd)
 138 {
 139   struct core_fns *cf;
 140   struct core_fns *yummy = NULL;
 141   int matches = 0;;
 142
 143   /* Don't sniff if we have support for register sets in CORE_GDBARCH.  */
 144   if (core_gdbarch && gdbarch_regset_from_core_section_p (core_gdbarch))
 145     return NULL;
 146
 147   for (cf = core_file_fns; cf != NULL; cf = cf->next)
 148     {
 149       if (cf->core_sniffer (cf, abfd))
 150         {
 151           yummy = cf;
 152           matches++;
 153         }
 154     }
 155   if (matches > 1)
 156     {
 157       warning ("\"%s\": ambiguous core format, %d handlers match",
 158                bfd_get_filename (abfd), matches);
 159     }
 160   else if (matches == 0)
 161     {
 162       warning ("\"%s\": no core file handler recognizes format, using default",
 163                bfd_get_filename (abfd));
 164     }
 165   if (yummy == NULL)
 166     {
 167       yummy = core_file_fns;
 168     }
 169   return (yummy);
 170 }
 171
 172 /* The default is to reject every core file format we see.  Either
 173    BFD has to recognize it, or we have to provide a function in the
 174    core file handler that recognizes it. */
 175
 176 int
 177 default_check_format (bfd *abfd)
 178 {
 179   return (0);
 180 }
 181
 182 /* Attempt to recognize core file formats that BFD rejects. */
 183
 184 static int
 185 gdb_check_format (bfd *abfd)
 186 {
 187   struct core_fns *cf;
 188
 189   for (cf = core_file_fns; cf != NULL; cf = cf->next)
 190     {
 191       if (cf->check_format (abfd))
 192         {
 193           return (1);
 194         }
 195     }
 196   return (0);
 197 }
 198
 199 /* Discard all vestiges of any previous core file and mark data and stack
 200    spaces as empty.  */
 201
 202 static void
 203 core_close (int quitting)
 204 {
 205   char *name;
 206
 207   if (core_bfd)
 208     {
 209       inferior_ptid = null_ptid;        /* Avoid confusion from thread stuff */
 210
 211       /* Clear out solib state while the bfd is still open. See
 212          comments in clear_solib in solib.c. */
 213 #ifdef CLEAR_SOLIB
 214       CLEAR_SOLIB ();
 215 #endif
 216
 217       name = bfd_get_filename (core_bfd);
 218       if (!bfd_close (core_bfd))
 219         warning ("cannot close \"%s\": %s",
 220                  name, bfd_errmsg (bfd_get_error ()));
 221       xfree (name);
 222       core_bfd = NULL;
 223       if (core_ops.to_sections)
 224         {
 225           xfree (core_ops.to_sections);
 226           core_ops.to_sections = NULL;
 227           core_ops.to_sections_end = NULL;
 228         }
 229     }
 230   core_vec = NULL;
 231   core_gdbarch = NULL;
 232 }
 233
 234 static void
 235 core_close_cleanup (void *ignore)
 236 {
 237   core_close (0/*ignored*/);
 238 }
 239
 240 #ifdef SOLIB_ADD
 241 /* Stub function for catch_errors around shared library hacking.  FROM_TTYP
 242    is really an int * which points to from_tty.  */
 243
 244 static int
 245 solib_add_stub (void *from_ttyp)
 246 {
 247   SOLIB_ADD (NULL, *(int *) from_ttyp, &current_target, auto_solib_add);
 248   re_enable_breakpoints_in_shlibs ();
 249   return 0;
 250 }
 251 #endif /* SOLIB_ADD */
 252
 253 /* Look for sections whose names start with `.reg/' so that we can extract the
 254    list of threads in a core file.  */
 255
 256 static void
 257 add_to_thread_list (bfd *abfd, asection *asect, void *reg_sect_arg)
 258 {
 259   int thread_id;
 260   asection *reg_sect = (asection *) reg_sect_arg;
 261
 262   if (strncmp (bfd_section_name (abfd, asect), ".reg/", 5) != 0)
 263     return;
 264
 265   thread_id = atoi (bfd_section_name (abfd, asect) + 5);
 266
 267   add_thread (pid_to_ptid (thread_id));
 268
 269 /* Warning, Will Robinson, looking at BFD private data! */
 270
 271   if (reg_sect != NULL
 272       && asect->filepos == reg_sect->filepos)   /* Did we find .reg? */
 273     inferior_ptid = pid_to_ptid (thread_id);    /* Yes, make it current */
 274 }
 275
 276 /* This routine opens and sets up the core file bfd.  */
 277
 278 static void
 279 core_open (char *filename, int from_tty)
 280 {
 281   const char *p;
 282   int siggy;
 283   struct cleanup *old_chain;
 284   char *temp;
 285   bfd *temp_bfd;
 286   int ontop;
 287   int scratch_chan;
 288   int flags;
 289
 290   target_preopen (from_tty);
 291   if (!filename)
 292     {
 293       error (core_bfd ?
 294              "No core file specified.  (Use `detach' to stop debugging a core file.)"
 295              : "No core file specified.");
 296     }
 297
 298   filename = tilde_expand (filename);
 299   if (filename[0] != '/')
 300     {
 301       temp = concat (current_directory, "/", filename, NULL);
 302       xfree (filename);
 303       filename = temp;
 304     }
 305
 306   old_chain = make_cleanup (xfree, filename);
 307
 308   flags = O_BINARY | O_LARGEFILE;
 309   if (write_files)
 310     flags |= O_RDWR;
 311   else
 312     flags |= O_RDONLY;
 313   scratch_chan = open (filename, flags, 0);
 314   if (scratch_chan < 0)
 315     perror_with_name (filename);
 316
 317   temp_bfd = bfd_fdopenr (filename, gnutarget, scratch_chan);
 318   if (temp_bfd == NULL)
 319     perror_with_name (filename);
 320
 321   if (!bfd_check_format (temp_bfd, bfd_core) &&
 322       !gdb_check_format (temp_bfd))
 323     {
 324       /* Do it after the err msg */
 325       /* FIXME: should be checking for errors from bfd_close (for one thing,
 326          on error it does not free all the storage associated with the
 327          bfd).  */
 328       make_cleanup_bfd_close (temp_bfd);
 329       error ("\"%s\" is not a core dump: %s",
 330              filename, bfd_errmsg (bfd_get_error ()));
 331     }
 332
 333   /* Looks semi-reasonable.  Toss the old core file and work on the new.  */
 334
 335   discard_cleanups (old_chain); /* Don't free filename any more */
 336   unpush_target (&core_ops);
 337   core_bfd = temp_bfd;
 338   old_chain = make_cleanup (core_close_cleanup, 0 /*ignore*/);
 339
 340   /* FIXME: kettenis/20031023: This is very dangerous.  The
 341      CORE_GDBARCH that results from this call may very well be
 342      different from CURRENT_GDBARCH.  However, its methods may only
 343      work if it is selected as the current architecture, because they
 344      rely on swapped data (see gdbarch.c).  We should get rid of that
 345      swapped data.  */
 346   core_gdbarch = gdbarch_from_bfd (core_bfd);
 347
 348   /* Find a suitable core file handler to munch on core_bfd */
 349   core_vec = sniff_core_bfd (core_bfd);
 350
 351   validate_files ();
 352
 353   /* Find the data section */
 354   if (build_section_table (core_bfd, &core_ops.to_sections,
 355                            &core_ops.to_sections_end))
 356     error ("\"%s\": Can't find sections: %s",
 357            bfd_get_filename (core_bfd), bfd_errmsg (bfd_get_error ()));
 358
 359   /* If we have no exec file, try to set the architecture from the
 360      core file.  We don't do this unconditionally since an exec file
 361      typically contains more information that helps us determine the
 362      architecture than a core file.  */
 363   if (!exec_bfd)
 364     set_gdbarch_from_file (core_bfd);
 365
 366   ontop = !push_target (&core_ops);
 367   discard_cleanups (old_chain);
 368
 369   /* This is done first, before anything has a chance to query the
 370      inferior for information such as symbols.  */
 371   observer_notify_inferior_created (&core_ops, from_tty);
 372
 373   p = bfd_core_file_failing_command (core_bfd);
 374   if (p)
 375     printf_filtered ("Core was generated by `%s'.\n", p);
 376
 377   siggy = bfd_core_file_failing_signal (core_bfd);
 378   if (siggy > 0)
 379     /* NOTE: target_signal_from_host() converts a target signal value
 380        into gdb's internal signal value.  Unfortunately gdb's internal
 381        value is called ``target_signal'' and this function got the
 382        name ..._from_host(). */
 383     printf_filtered ("Program terminated with signal %d, %s.\n", siggy,
 384                      target_signal_to_string (target_signal_from_host (siggy)));
 385
 386   /* Build up thread list from BFD sections. */
 387
 388   init_thread_list ();
 389   bfd_map_over_sections (core_bfd, add_to_thread_list,
 390                          bfd_get_section_by_name (core_bfd, ".reg"));
 391
 392   if (ontop)
 393     {
 394       /* Fetch all registers from core file.  */
 395       target_fetch_registers (-1);
 396
 397       /* Add symbols and section mappings for any shared libraries.  */
 398 #ifdef SOLIB_ADD
 399       catch_errors (solib_add_stub, &from_tty, (char *) 0,
 400                     RETURN_MASK_ALL);
 401 #endif
 402
 403       /* Now, set up the frame cache, and print the top of stack.  */
 404       flush_cached_frames ();
 405       select_frame (get_current_frame ());
 406       print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
 407     }
 408   else
 409     {
 410       warning (
 411                 "you won't be able to access this core file until you terminate\n\
 412 your %s; do ``info files''", target_longname);
 413     }
 414 }
 415
 416 static void
 417 core_detach (char *args, int from_tty)
 418 {
 419   if (args)
 420     error ("Too many arguments");
 421   unpush_target (&core_ops);
 422   reinit_frame_cache ();
 423   if (from_tty)
 424     printf_filtered ("No core file now.\n");
 425 }
 426
 427
 428 /* Try to retrieve registers from a section in core_bfd, and supply
 429    them to core_vec->core_read_registers, as the register set numbered
 430    WHICH.
 431
 432    If inferior_ptid is zero, do the single-threaded thing: look for a
 433    section named NAME.  If inferior_ptid is non-zero, do the
 434    multi-threaded thing: look for a section named "NAME/PID", where
 435    PID is the shortest ASCII decimal representation of inferior_ptid.
 436
 437    HUMAN_NAME is a human-readable name for the kind of registers the
 438    NAME section contains, for use in error messages.
 439
 440    If REQUIRED is non-zero, print an error if the core file doesn't
 441    have a section by the appropriate name.  Otherwise, just do nothing.  */
 442
 443 static void
 444 get_core_register_section (char *name,
 445                            int which,
 446                            char *human_name,
 447                            int required)
 448 {
 449   char section_name[100];
 450   struct bfd_section *section;
 451   bfd_size_type size;
 452   char *contents;
 453
 454   if (PIDGET (inferior_ptid))
 455     sprintf (section_name, "%s/%d", name, PIDGET (inferior_ptid));
 456   else
 457     strcpy (section_name, name);
 458
 459   section = bfd_get_section_by_name (core_bfd, section_name);
 460   if (! section)
 461     {
 462       if (required)
 463         warning ("Couldn't find %s registers in core file.\n", human_name);
 464       return;
 465     }
 466
 467   size = bfd_section_size (core_bfd, section);
 468   contents = alloca (size);
 469   if (! bfd_get_section_contents (core_bfd, section, contents,
 470                                   (file_ptr) 0, size))
 471     {
 472       warning ("Couldn't read %s registers from `%s' section in core file.\n",
 473                human_name, name);
 474       return;
 475     }
 476
 477   if (core_gdbarch && gdbarch_regset_from_core_section_p (core_gdbarch))
 478     {
 479       const struct regset *regset;
 480
 481       regset = gdbarch_regset_from_core_section (core_gdbarch, name, size);
 482       if (regset == NULL)
 483         {
 484           if (required)
 485             warning ("Couldn't recognize %s registers in core file.\n",
 486                      human_name);
 487           return;
 488         }
 489
 490       regset->supply_regset (regset, current_regcache, -1, contents, size);
 491       return;
 492     }
 493
 494   gdb_assert (core_vec);
 495   core_vec->core_read_registers (contents, size, which,
 496                                  ((CORE_ADDR)
 497                                   bfd_section_vma (core_bfd, section)));
 498 }
 499
 500
 501 /* Get the registers out of a core file.  This is the machine-
 502    independent part.  Fetch_core_registers is the machine-dependent
 503    part, typically implemented in the xm-file for each architecture.  */
 504
 505 /* We just get all the registers, so we don't use regno.  */
 506
 507 static void
 508 get_core_registers (int regno)
 509 {
 510   int status;
 511
 512   if (!(core_gdbarch && gdbarch_regset_from_core_section_p (core_gdbarch))
 513       && (core_vec == NULL || core_vec->core_read_registers == NULL))
 514     {
 515       fprintf_filtered (gdb_stderr,
 516                      "Can't fetch registers from this type of core file\n");
 517       return;
 518     }
 519
 520   get_core_register_section (".reg", 0, "general-purpose", 1);
 521   get_core_register_section (".reg2", 2, "floating-point", 0);
 522   get_core_register_section (".reg-xfp", 3, "extended floating-point", 0);
 523
 524   deprecated_registers_fetched ();
 525 }
 526
 527 static void
 528 core_files_info (struct target_ops *t)
 529 {
 530   print_section_info (t, core_bfd);
 531 }
 532 \f
 533 static LONGEST
 534 core_xfer_partial (struct target_ops *ops, enum target_object object,
 535                    const char *annex, void *readbuf,
 536                    const void *writebuf, ULONGEST offset, LONGEST len)
 537 {
 538   switch (object)
 539     {
 540     case TARGET_OBJECT_MEMORY:
 541       if (readbuf)
 542         return (*ops->deprecated_xfer_memory) (offset, readbuf, len,
 543                                                0/*write*/, NULL, ops);
 544       if (writebuf)
 545         return (*ops->deprecated_xfer_memory) (offset, readbuf, len,
 546                                                1/*write*/, NULL, ops);
 547       return -1;
 548
 549     case TARGET_OBJECT_AUXV:
 550       if (readbuf)
 551         {
 552           /* When the aux vector is stored in core file, BFD
 553              represents this with a fake section called ".auxv".  */
 554
 555           struct bfd_section *section;
 556           bfd_size_type size;
 557           char *contents;
 558
 559           section = bfd_get_section_by_name (core_bfd, ".auxv");
 560           if (section == NULL)
 561             return -1;
 562
 563           size = bfd_section_size (core_bfd, section);
 564           if (offset >= size)
 565             return 0;
 566           size -= offset;
 567           if (size > len)
 568             size = len;
 569           if (size > 0
 570               && !bfd_get_section_contents (core_bfd, section, readbuf,
 571                                             (file_ptr) offset, size))
 572             {
 573               warning ("Couldn't read NT_AUXV note in core file.");
 574               return -1;
 575             }
 576
 577           return size;
 578         }
 579       return -1;
 580
 581     case TARGET_OBJECT_WCOOKIE:
 582       if (readbuf)
 583         {
 584           /* When the StackGhost cookie is stored in core file, BFD
 585              represents this with a fake section called ".wcookie".  */
 586
 587           struct bfd_section *section;
 588           bfd_size_type size;
 589           char *contents;
 590
 591           section = bfd_get_section_by_name (core_bfd, ".wcookie");
 592           if (section == NULL)
 593             return -1;
 594
 595           size = bfd_section_size (core_bfd, section);
 596           if (offset >= size)
 597             return 0;
 598           size -= offset;
 599           if (size > len)
 600             size = len;
 601           if (size > 0
 602               && !bfd_get_section_contents (core_bfd, section, readbuf,
 603                                             (file_ptr) offset, size))
 604             {
 605               warning ("Couldn't read StackGhost cookie in core file.");
 606               return -1;
 607             }
 608
 609           return size;
 610         }
 611       return -1;
 612
 613     default:
 614       if (ops->beneath != NULL)
 615         return ops->beneath->to_xfer_partial (ops->beneath, object, annex,
 616                                               readbuf, writebuf, offset, len);
 617       return -1;
 618     }
 619 }
 620
 621 \f
 622 /* If mourn is being called in all the right places, this could be say
 623    `gdb internal error' (since generic_mourn calls breakpoint_init_inferior).  */
 624
 625 static int
 626 ignore (CORE_ADDR addr, char *contents)
 627 {
 628   return 0;
 629 }
 630
 631
 632 /* Okay, let's be honest: threads gleaned from a core file aren't
 633    exactly lively, are they?  On the other hand, if we don't claim
 634    that each & every one is alive, then we don't get any of them
 635    to appear in an "info thread" command, which is quite a useful
 636    behaviour.
 637  */
 638 static int
 639 core_file_thread_alive (ptid_t tid)
 640 {
 641   return 1;
 642 }
 643
 644 /* Fill in core_ops with its defined operations and properties.  */
 645
 646 static void
 647 init_core_ops (void)
 648 {
 649   core_ops.to_shortname = "core";
 650   core_ops.to_longname = "Local core dump file";
 651   core_ops.to_doc =
 652     "Use a core file as a target.  Specify the filename of the core file.";
 653   core_ops.to_open = core_open;
 654   core_ops.to_close = core_close;
 655   core_ops.to_attach = find_default_attach;
 656   core_ops.to_detach = core_detach;
 657   core_ops.to_fetch_registers = get_core_registers;
 658   core_ops.to_xfer_partial = core_xfer_partial;
 659   core_ops.deprecated_xfer_memory = xfer_memory;
 660   core_ops.to_files_info = core_files_info;
 661   core_ops.to_insert_breakpoint = ignore;
 662   core_ops.to_remove_breakpoint = ignore;
 663   core_ops.to_create_inferior = find_default_create_inferior;
 664   core_ops.to_thread_alive = core_file_thread_alive;
 665   core_ops.to_stratum = core_stratum;
 666   core_ops.to_has_memory = 1;
 667   core_ops.to_has_stack = 1;
 668   core_ops.to_has_registers = 1;
 669   core_ops.to_magic = OPS_MAGIC;
 670 }
 671
 672 /* non-zero if we should not do the add_target call in
 673    _initialize_corelow; not initialized (i.e., bss) so that
 674    the target can initialize it (i.e., data) if appropriate.
 675    This needs to be set at compile time because we don't know
 676    for sure whether the target's initialize routine is called
 677    before us or after us. */
 678 int coreops_suppress_target;
 679
 680 void
 681 _initialize_corelow (void)
 682 {
 683   init_core_ops ();
 684
 685   if (!coreops_suppress_target)
 686     add_target (&core_ops);
 687 }