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, 2005
   5    Free Software Foundation, 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 #include "solib.h"
  50
  51 #ifndef O_BINARY
  52 #define O_BINARY 0
  53 #endif
  54
  55 #ifndef O_LARGEFILE
  56 #define O_LARGEFILE 0
  57 #endif
  58
  59 /* List of all available core_fns.  On gdb startup, each core file
  60    register reader calls deprecated_add_core_fns() to register
  61    information on each core format it is prepared to read.  */
  62
  63 static struct core_fns *core_file_fns = NULL;
  64
  65 /* The core_fns for a core file handler that is prepared to read the core
  66    file currently open on core_bfd. */
  67
  68 static struct core_fns *core_vec = NULL;
  69
  70 /* FIXME: kettenis/20031023: Eventually this variable should
  71    disappear.  */
  72
  73 struct gdbarch *core_gdbarch = NULL;
  74
  75 static void core_files_info (struct target_ops *);
  76
  77 static struct core_fns *sniff_core_bfd (bfd *);
  78
  79 static int gdb_check_format (bfd *);
  80
  81 static void core_open (char *, int);
  82
  83 static void core_detach (char *, int);
  84
  85 static void core_close (int);
  86
  87 static void core_close_cleanup (void *ignore);
  88
  89 static void get_core_registers (int);
  90
  91 static void add_to_thread_list (bfd *, asection *, void *);
  92
  93 static int ignore (CORE_ADDR, bfd_byte *);
  94
  95 static int core_file_thread_alive (ptid_t tid);
  96
  97 static void init_core_ops (void);
  98
  99 void _initialize_corelow (void);
 100
 101 struct target_ops core_ops;
 102
 103 /* Link a new core_fns into the global core_file_fns list.  Called on gdb
 104    startup by the _initialize routine in each core file register reader, to
 105    register information about each format the the reader is prepared to
 106    handle. */
 107
 108 void
 109 deprecated_add_core_fns (struct core_fns *cf)
 110 {
 111   cf->next = core_file_fns;
 112   core_file_fns = cf;
 113 }
 114
 115 /* The default function that core file handlers can use to examine a
 116    core file BFD and decide whether or not to accept the job of
 117    reading the core file. */
 118
 119 int
 120 default_core_sniffer (struct core_fns *our_fns, bfd *abfd)
 121 {
 122   int result;
 123
 124   result = (bfd_get_flavour (abfd) == our_fns -> core_flavour);
 125   return (result);
 126 }
 127
 128 /* Walk through the list of core functions to find a set that can
 129    handle the core file open on ABFD.  Default to the first one in the
 130    list if nothing matches.  Returns pointer to set that is
 131    selected. */
 132
 133 static struct core_fns *
 134 sniff_core_bfd (bfd *abfd)
 135 {
 136   struct core_fns *cf;
 137   struct core_fns *yummy = NULL;
 138   int matches = 0;;
 139
 140   /* Don't sniff if we have support for register sets in CORE_GDBARCH.  */
 141   if (core_gdbarch && gdbarch_regset_from_core_section_p (core_gdbarch))
 142     return NULL;
 143
 144   for (cf = core_file_fns; cf != NULL; cf = cf->next)
 145     {
 146       if (cf->core_sniffer (cf, abfd))
 147         {
 148           yummy = cf;
 149           matches++;
 150         }
 151     }
 152   if (matches > 1)
 153     {
 154       warning (_("\"%s\": ambiguous core format, %d handlers match"),
 155                bfd_get_filename (abfd), matches);
 156     }
 157   else if (matches == 0)
 158     {
 159       warning (_("\"%s\": no core file handler recognizes format, using default"),
 160                bfd_get_filename (abfd));
 161     }
 162   if (yummy == NULL)
 163     {
 164       yummy = core_file_fns;
 165     }
 166   return (yummy);
 167 }
 168
 169 /* The default is to reject every core file format we see.  Either
 170    BFD has to recognize it, or we have to provide a function in the
 171    core file handler that recognizes it. */
 172
 173 int
 174 default_check_format (bfd *abfd)
 175 {
 176   return (0);
 177 }
 178
 179 /* Attempt to recognize core file formats that BFD rejects. */
 180
 181 static int
 182 gdb_check_format (bfd *abfd)
 183 {
 184   struct core_fns *cf;
 185
 186   for (cf = core_file_fns; cf != NULL; cf = cf->next)
 187     {
 188       if (cf->check_format (abfd))
 189         {
 190           return (1);
 191         }
 192     }
 193   return (0);
 194 }
 195
 196 /* Discard all vestiges of any previous core file and mark data and stack
 197    spaces as empty.  */
 198
 199 static void
 200 core_close (int quitting)
 201 {
 202   char *name;
 203
 204   if (core_bfd)
 205     {
 206       inferior_ptid = null_ptid;        /* Avoid confusion from thread stuff */
 207
 208       /* Clear out solib state while the bfd is still open. See
 209          comments in clear_solib in solib.c. */
 210 #ifdef CLEAR_SOLIB
 211       CLEAR_SOLIB ();
 212 #else
 213       clear_solib ();
 214 #endif
 215
 216       name = bfd_get_filename (core_bfd);
 217       if (!bfd_close (core_bfd))
 218         warning (_("cannot close \"%s\": %s"),
 219                  name, bfd_errmsg (bfd_get_error ()));
 220       xfree (name);
 221       core_bfd = NULL;
 222       if (core_ops.to_sections)
 223         {
 224           xfree (core_ops.to_sections);
 225           core_ops.to_sections = NULL;
 226           core_ops.to_sections_end = NULL;
 227         }
 228     }
 229   core_vec = NULL;
 230   core_gdbarch = NULL;
 231 }
 232
 233 static void
 234 core_close_cleanup (void *ignore)
 235 {
 236   core_close (0/*ignored*/);
 237 }
 238
 239 /* Stub function for catch_errors around shared library hacking.  FROM_TTYP
 240    is really an int * which points to from_tty.  */
 241
 242 static int
 243 solib_add_stub (void *from_ttyp)
 244 {
 245 #ifdef SOLIB_ADD
 246   SOLIB_ADD (NULL, *(int *) from_ttyp, &current_target, auto_solib_add);
 247 #else
 248   solib_add (NULL, *(int *)from_ttyp, &current_target, auto_solib_add);
 249 #endif
 250   re_enable_breakpoints_in_shlibs ();
 251   return 0;
 252 }
 253
 254 /* Look for sections whose names start with `.reg/' so that we can extract the
 255    list of threads in a core file.  */
 256
 257 static void
 258 add_to_thread_list (bfd *abfd, asection *asect, void *reg_sect_arg)
 259 {
 260   int thread_id;
 261   asection *reg_sect = (asection *) reg_sect_arg;
 262
 263   if (strncmp (bfd_section_name (abfd, asect), ".reg/", 5) != 0)
 264     return;
 265
 266   thread_id = atoi (bfd_section_name (abfd, asect) + 5);
 267
 268   add_thread (pid_to_ptid (thread_id));
 269
 270 /* Warning, Will Robinson, looking at BFD private data! */
 271
 272   if (reg_sect != NULL
 273       && asect->filepos == reg_sect->filepos)   /* Did we find .reg? */
 274     inferior_ptid = pid_to_ptid (thread_id);    /* Yes, make it current */
 275 }
 276
 277 /* This routine opens and sets up the core file bfd.  */
 278
 279 static void
 280 core_open (char *filename, int from_tty)
 281 {
 282   const char *p;
 283   int siggy;
 284   struct cleanup *old_chain;
 285   char *temp;
 286   bfd *temp_bfd;
 287   int ontop;
 288   int scratch_chan;
 289   int flags;
 290
 291   target_preopen (from_tty);
 292   if (!filename)
 293     {
 294       if (core_bfd)
 295         error (_("No core file specified.  (Use `detach' to stop debugging a core file.)"));
 296       else
 297         error (_("No core file specified."));
 298     }
 299
 300   filename = tilde_expand (filename);
 301   if (filename[0] != '/')
 302     {
 303       temp = concat (current_directory, "/", filename, NULL);
 304       xfree (filename);
 305       filename = temp;
 306     }
 307
 308   old_chain = make_cleanup (xfree, filename);
 309
 310   flags = O_BINARY | O_LARGEFILE;
 311   if (write_files)
 312     flags |= O_RDWR;
 313   else
 314     flags |= O_RDONLY;
 315   scratch_chan = open (filename, flags, 0);
 316   if (scratch_chan < 0)
 317     perror_with_name (filename);
 318
 319   temp_bfd = bfd_fdopenr (filename, gnutarget, scratch_chan);
 320   if (temp_bfd == NULL)
 321     perror_with_name (filename);
 322
 323   if (!bfd_check_format (temp_bfd, bfd_core) &&
 324       !gdb_check_format (temp_bfd))
 325     {
 326       /* Do it after the err msg */
 327       /* FIXME: should be checking for errors from bfd_close (for one thing,
 328          on error it does not free all the storage associated with the
 329          bfd).  */
 330       make_cleanup_bfd_close (temp_bfd);
 331       error (_("\"%s\" is not a core dump: %s"),
 332              filename, bfd_errmsg (bfd_get_error ()));
 333     }
 334
 335   /* Looks semi-reasonable.  Toss the old core file and work on the new.  */
 336
 337   discard_cleanups (old_chain); /* Don't free filename any more */
 338   unpush_target (&core_ops);
 339   core_bfd = temp_bfd;
 340   old_chain = make_cleanup (core_close_cleanup, 0 /*ignore*/);
 341
 342   /* FIXME: kettenis/20031023: This is very dangerous.  The
 343      CORE_GDBARCH that results from this call may very well be
 344      different from CURRENT_GDBARCH.  However, its methods may only
 345      work if it is selected as the current architecture, because they
 346      rely on swapped data (see gdbarch.c).  We should get rid of that
 347      swapped data.  */
 348   core_gdbarch = gdbarch_from_bfd (core_bfd);
 349
 350   /* Find a suitable core file handler to munch on core_bfd */
 351   core_vec = sniff_core_bfd (core_bfd);
 352
 353   validate_files ();
 354
 355   /* Find the data section */
 356   if (build_section_table (core_bfd, &core_ops.to_sections,
 357                            &core_ops.to_sections_end))
 358     error (_("\"%s\": Can't find sections: %s"),
 359            bfd_get_filename (core_bfd), bfd_errmsg (bfd_get_error ()));
 360
 361   /* If we have no exec file, try to set the architecture from the
 362      core file.  We don't do this unconditionally since an exec file
 363      typically contains more information that helps us determine the
 364      architecture than a core file.  */
 365   if (!exec_bfd)
 366     set_gdbarch_from_file (core_bfd);
 367
 368   ontop = !push_target (&core_ops);
 369   discard_cleanups (old_chain);
 370
 371   /* This is done first, before anything has a chance to query the
 372      inferior for information such as symbols.  */
 373   observer_notify_inferior_created (&core_ops, from_tty);
 374
 375   p = bfd_core_file_failing_command (core_bfd);
 376   if (p)
 377     printf_filtered (_("Core was generated by `%s'.\n"), p);
 378
 379   siggy = bfd_core_file_failing_signal (core_bfd);
 380   if (siggy > 0)
 381     /* NOTE: target_signal_from_host() converts a target signal value
 382        into gdb's internal signal value.  Unfortunately gdb's internal
 383        value is called ``target_signal'' and this function got the
 384        name ..._from_host(). */
 385     printf_filtered (_("Program terminated with signal %d, %s.\n"), siggy,
 386                      target_signal_to_string (target_signal_from_host (siggy)));
 387
 388   /* Build up thread list from BFD sections. */
 389
 390   init_thread_list ();
 391   bfd_map_over_sections (core_bfd, add_to_thread_list,
 392                          bfd_get_section_by_name (core_bfd, ".reg"));
 393
 394   if (ontop)
 395     {
 396       /* Fetch all registers from core file.  */
 397       target_fetch_registers (-1);
 398
 399       /* Add symbols and section mappings for any shared libraries.  */
 400       catch_errors (solib_add_stub, &from_tty, (char *) 0, RETURN_MASK_ALL);
 401
 402       /* Now, set up the frame cache, and print the top of stack.  */
 403       flush_cached_frames ();
 404       select_frame (get_current_frame ());
 405       print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
 406     }
 407   else
 408     {
 409       warning (
 410                 "you won't be able to access this core file until you terminate\n\
 411 your %s; do ``info files''", target_longname);
 412     }
 413 }
 414
 415 static void
 416 core_detach (char *args, int from_tty)
 417 {
 418   if (args)
 419     error (_("Too many arguments"));
 420   unpush_target (&core_ops);
 421   reinit_frame_cache ();
 422   if (from_tty)
 423     printf_filtered (_("No core file now.\n"));
 424 }
 425
 426
 427 /* Try to retrieve registers from a section in core_bfd, and supply
 428    them to core_vec->core_read_registers, as the register set numbered
 429    WHICH.
 430
 431    If inferior_ptid is zero, do the single-threaded thing: look for a
 432    section named NAME.  If inferior_ptid is non-zero, do the
 433    multi-threaded thing: look for a section named "NAME/PID", where
 434    PID is the shortest ASCII decimal representation of inferior_ptid.
 435
 436    HUMAN_NAME is a human-readable name for the kind of registers the
 437    NAME section contains, for use in error messages.
 438
 439    If REQUIRED is non-zero, print an error if the core file doesn't
 440    have a section by the appropriate name.  Otherwise, just do nothing.  */
 441
 442 static void
 443 get_core_register_section (char *name,
 444                            int which,
 445                            char *human_name,
 446                            int required)
 447 {
 448   static char *section_name = NULL;
 449   struct bfd_section *section;
 450   bfd_size_type size;
 451   char *contents;
 452
 453   xfree (section_name);
 454   if (PIDGET (inferior_ptid))
 455     section_name = xstrprintf ("%s/%d", name, PIDGET (inferior_ptid));
 456   else
 457     section_name = xstrdup (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."), 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."),
 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."),
 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, gdb_byte *readbuf,
 536                    const gdb_byte *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, bfd_byte *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 }