gdb/corefile.c

/* Core dump and executable file functions above target vector, for GDB.

   Copyright (C) 1986-2024 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <signal.h>
#include <fcntl.h>
#include "event-top.h"
#include "extract-store-integer.h"
#include "inferior.h"
#include "symtab.h"
#include "command.h"
#include "cli/cli-cmds.h"
#include "bfd.h"
#include "target.h"
#include "gdbcore.h"
#include "dis-asm.h"
#include <sys/stat.h>
#include "completer.h"
#include "observable.h"
#include "cli/cli-utils.h"
#include "gdbarch.h"
#include "interps.h"

void
reopen_exec_file (void)
{
  bfd *exec_bfd = current_program_space->exec_bfd ();

  /* Don't do anything if there isn't an exec file.  */
  if (exec_bfd == nullptr)
    return;

  /* The main executable can't be an in-memory BFD object.  If it was then
     the use of bfd_stat below would not work as expected.  */
  gdb_assert ((exec_bfd->flags & BFD_IN_MEMORY) == 0);

  /* If the timestamp of the exec file has changed, reopen it.  */
  struct stat st;
  int res = bfd_stat (exec_bfd, &st);

  if (res == 0
      && current_program_space->ebfd_mtime != 0
      && current_program_space->ebfd_mtime != st.st_mtime)
    exec_file_attach (bfd_get_filename (exec_bfd), 0);
}

/* If we have both a core file and an exec file,
   print a warning if they don't go together.  */

void
validate_files (void)
{
  if (current_program_space->exec_bfd () && current_program_space->core_bfd ())
    {
      if (!core_file_matches_executable_p (current_program_space->core_bfd (),
					   current_program_space->exec_bfd ()))
	warning (_("core file may not match specified executable file."));
      else if (bfd_get_mtime (current_program_space->exec_bfd ())
	       > bfd_get_mtime (current_program_space->core_bfd ()))
	warning (_("exec file is newer than core file."));
    }
}

std::string
memory_error_message (enum target_xfer_status err,
		      struct gdbarch *gdbarch, CORE_ADDR memaddr)
{
  switch (err)
    {
    case TARGET_XFER_E_IO:
      /* Actually, address between memaddr and memaddr + len was out of
	 bounds.  */
      return string_printf (_("Cannot access memory at address %s"),
			    paddress (gdbarch, memaddr));
    case TARGET_XFER_UNAVAILABLE:
      return string_printf (_("Memory at address %s unavailable."),
			    paddress (gdbarch, memaddr));
    default:
      internal_error ("unhandled target_xfer_status: %s (%s)",
		      target_xfer_status_to_string (err),
		      plongest (err));
    }
}

/* Report a memory error by throwing a suitable exception.  */

void
memory_error (enum target_xfer_status err, CORE_ADDR memaddr)
{
  enum errors exception = GDB_NO_ERROR;

  /* Build error string.  */
  std::string str
    = memory_error_message (err, current_inferior ()->arch (), memaddr);

  /* Choose the right error to throw.  */
  switch (err)
    {
    case TARGET_XFER_E_IO:
      exception = MEMORY_ERROR;
      break;
    case TARGET_XFER_UNAVAILABLE:
      exception = NOT_AVAILABLE_ERROR;
      break;
    }

  /* Throw it.  */
  throw_error (exception, ("%s"), str.c_str ());
}

/* Helper function.  */

static void
read_memory_object (enum target_object object, CORE_ADDR memaddr,
		    gdb_byte *myaddr, ssize_t len)
{
  ULONGEST xfered = 0;

  while (xfered < len)
    {
      enum target_xfer_status status;
      ULONGEST xfered_len;

      status = target_xfer_partial (current_inferior ()->top_target (), object,
				    NULL, myaddr + xfered, NULL,
				    memaddr + xfered, len - xfered,
				    &xfered_len);

      if (status != TARGET_XFER_OK)
	memory_error (status == TARGET_XFER_EOF ? TARGET_XFER_E_IO : status,
		      memaddr + xfered);

      xfered += xfered_len;
      QUIT;
    }
}

/* Same as target_read_memory, but report an error if can't read.  */

void
read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
{
  read_memory_object (TARGET_OBJECT_MEMORY, memaddr, myaddr, len);
}

/* Same as target_read_stack, but report an error if can't read.  */

void
read_stack (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
{
  read_memory_object (TARGET_OBJECT_STACK_MEMORY, memaddr, myaddr, len);
}

/* Same as target_read_code, but report an error if can't read.  */

void
read_code (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
{
  read_memory_object (TARGET_OBJECT_CODE_MEMORY, memaddr, myaddr, len);
}

/* Read memory at MEMADDR of length LEN and put the contents in
   RETURN_VALUE.  Return 0 if MEMADDR couldn't be read and non-zero
   if successful.  */

int
safe_read_memory_integer (CORE_ADDR memaddr, int len, 
			  enum bfd_endian byte_order,
			  LONGEST *return_value)
{
  gdb_byte buf[sizeof (LONGEST)];

  if (target_read_memory (memaddr, buf, len))
    return 0;

  *return_value = extract_signed_integer (buf, len, byte_order);
  return 1;
}

/* Read memory at MEMADDR of length LEN and put the contents in
   RETURN_VALUE.  Return 0 if MEMADDR couldn't be read and non-zero
   if successful.  */

int
safe_read_memory_unsigned_integer (CORE_ADDR memaddr, int len,
				   enum bfd_endian byte_order,
				   ULONGEST *return_value)
{
  gdb_byte buf[sizeof (ULONGEST)];

  if (target_read_memory (memaddr, buf, len))
    return 0;

  *return_value = extract_unsigned_integer (buf, len, byte_order);
  return 1;
}

LONGEST
read_memory_integer (CORE_ADDR memaddr, int len,
		     enum bfd_endian byte_order)
{
  gdb_byte buf[sizeof (LONGEST)];

  read_memory (memaddr, buf, len);
  return extract_signed_integer (buf, len, byte_order);
}

ULONGEST
read_memory_unsigned_integer (CORE_ADDR memaddr, int len,
			      enum bfd_endian byte_order)
{
  gdb_byte buf[sizeof (ULONGEST)];

  read_memory (memaddr, buf, len);
  return extract_unsigned_integer (buf, len, byte_order);
}

LONGEST
read_code_integer (CORE_ADDR memaddr, int len,
		   enum bfd_endian byte_order)
{
  gdb_byte buf[sizeof (LONGEST)];

  read_code (memaddr, buf, len);
  return extract_signed_integer (buf, len, byte_order);
}

ULONGEST
read_code_unsigned_integer (CORE_ADDR memaddr, int len,
			    enum bfd_endian byte_order)
{
  gdb_byte buf[sizeof (ULONGEST)];

  read_code (memaddr, buf, len);
  return extract_unsigned_integer (buf, len, byte_order);
}

CORE_ADDR
read_memory_typed_address (CORE_ADDR addr, struct type *type)
{
  gdb_byte *buf = (gdb_byte *) alloca (type->length ());

  read_memory (addr, buf, type->length ());
  return extract_typed_address (buf, type);
}

/* See gdbcore.h.  */

void
write_memory (CORE_ADDR memaddr, 
	      const bfd_byte *myaddr, ssize_t len)
{
  int status;

  status = target_write_memory (memaddr, myaddr, len);
  if (status != 0)
    memory_error (TARGET_XFER_E_IO, memaddr);
}

/* Notify interpreters and observers that INF's memory was changed.  */

static void
notify_memory_changed (inferior *inf, CORE_ADDR addr, ssize_t len,
		       const bfd_byte *data)
{
  interps_notify_memory_changed (inf, addr, len, data);
  gdb::observers::memory_changed.notify (inf, addr, len, data);
}

/* Same as write_memory, but notify 'memory_changed' observers.  */

void
write_memory_with_notification (CORE_ADDR memaddr, const bfd_byte *myaddr,
				ssize_t len)
{
  write_memory (memaddr, myaddr, len);
  notify_memory_changed (current_inferior (), memaddr, len, myaddr);
}

/* Store VALUE at ADDR in the inferior as a LEN-byte unsigned
   integer.  */
void
write_memory_unsigned_integer (CORE_ADDR addr, int len, 
			       enum bfd_endian byte_order,
			       ULONGEST value)
{
  gdb_byte *buf = (gdb_byte *) alloca (len);

  store_unsigned_integer (buf, len, byte_order, value);
  write_memory (addr, buf, len);
}

/* Store VALUE at ADDR in the inferior as a LEN-byte signed
   integer.  */
void
write_memory_signed_integer (CORE_ADDR addr, int len, 
			     enum bfd_endian byte_order,
			     LONGEST value)
{
  gdb_byte *buf = (gdb_byte *) alloca (len);

  store_signed_integer (buf, len, byte_order, value);
  write_memory (addr, buf, len);
}

/* The current default bfd target.  Points to storage allocated for
   gnutarget_string.  */
const char *gnutarget;

/* Same thing, except it is "auto" not NULL for the default case.  */
static std::string gnutarget_string;
static void
show_gnutarget_string (struct ui_file *file, int from_tty,
		       struct cmd_list_element *c,
		       const char *value)
{
  gdb_printf (file,
	      _("The current BFD target is \"%s\".\n"), value);
}

static void
set_gnutarget_command (const char *ignore, int from_tty,
		       struct cmd_list_element *c)
{
  const char *gend = gnutarget_string.c_str () + gnutarget_string.size ();
  gend = remove_trailing_whitespace (gnutarget_string.c_str (), gend);
  gnutarget_string
    = gnutarget_string.substr (0, gend - gnutarget_string.data ());

  if (gnutarget_string == "auto")
    gnutarget = NULL;
  else
    gnutarget = gnutarget_string.c_str ();
}

/* A completion function for "set gnutarget".  */

static void
complete_set_gnutarget (struct cmd_list_element *cmd,
			completion_tracker &tracker,
			const char *text, const char *word)
{
  static const char **bfd_targets;

  if (bfd_targets == NULL)
    {
      int last;

      bfd_targets = bfd_target_list ();
      for (last = 0; bfd_targets[last] != NULL; ++last)
	;

      bfd_targets = XRESIZEVEC (const char *, bfd_targets, last + 2);
      bfd_targets[last] = "auto";
      bfd_targets[last + 1] = NULL;
    }

  complete_on_enum (tracker, bfd_targets, text, word);
}

/* Set the gnutarget.  */
void
set_gnutarget (const char *newtarget)
{
  gnutarget_string = newtarget;
  set_gnutarget_command (NULL, 0, NULL);
}

void _initialize_core ();
void
_initialize_core ()
{
  cmd_list_element *core_file_cmd
    = add_cmd ("core-file", class_files, core_file_command, _("\
Use FILE as core dump for examining memory and registers.\n\
Usage: core-file FILE\n\
No arg means have no core file.  This command has been superseded by the\n\
`target core' and `detach' commands."), &cmdlist);
  set_cmd_completer (core_file_cmd, filename_completer);

  
  set_show_commands set_show_gnutarget
    = add_setshow_string_noescape_cmd ("gnutarget", class_files,
				       &gnutarget_string, _("\
Set the current BFD target."), _("\
Show the current BFD target."), _("\
Use `set gnutarget auto' to specify automatic detection."),
				       set_gnutarget_command,
				       show_gnutarget_string,
				       &setlist, &showlist);
  set_cmd_completer (set_show_gnutarget.set, complete_set_gnutarget);

  add_alias_cmd ("g", set_show_gnutarget.set, class_files, 1, &setlist);

  if (getenv ("GNUTARGET"))
    set_gnutarget (getenv ("GNUTARGET"));
  else
    set_gnutarget ("auto");
}