target.c

早期freebsd实现

/* Select target systems and architectures at runtime for GDB.
   Copyright 1990, 1992 Free Software Foundation, Inc.
   Contributed by Cygnus Support.

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 2 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "defs.h"
#include <errno.h>
#include <ctype.h>
#include "target.h"
#include "gdbcmd.h"
#include "symtab.h"
#include "inferior.h"
#include "bfd.h"
#include "symfile.h"
#include "objfiles.h"

extern int errno;

static void
target_info PARAMS ((char *, int));

static void
cleanup_target PARAMS ((struct target_ops *));

static void
maybe_kill_then_create_inferior PARAMS ((char *, char *, char **));

static void
maybe_kill_then_attach PARAMS ((char *, int));

static void
kill_or_be_killed PARAMS ((int));

static void
default_terminal_info PARAMS ((char *, int));

static int
nosymbol PARAMS ((char *, CORE_ADDR *));

static void
tcomplain PARAMS ((void));

static int
nomemory PARAMS ((CORE_ADDR, char *, int, int));

static int
return_zero PARAMS ((void));

static void
ignore PARAMS ((void));

static void
target_command PARAMS ((char *, int));

static struct target_ops *
find_default_run_target PARAMS ((char *));

/* Pointer to array of target architecture structures; the size of the
   array; the current index into the array; the allocated size of the 
   array.  */
struct target_ops **target_structs;
unsigned target_struct_size;
unsigned target_struct_index;
unsigned target_struct_allocsize;
#define	DEFAULT_ALLOCSIZE	10

/* The initial current target, so that there is always a semi-valid
   current target.  */

struct target_ops dummy_target = {"None", "None", "",
    0, 0, 		/* open, close */
    find_default_attach, 0,  /* attach, detach */
    0, 0,		/* resume, wait */
    0, 0, 0,		/* registers */
    0, 0, 		/* memory */
    0, 0, 		/* bkpts */
    0, 0, 0, 0, 0, 	/* terminal */
    0, 0, 		/* kill, load */
    0, 			/* lookup_symbol */
    find_default_create_inferior, /* create_inferior */
    0,			/* mourn_inferior */
    0,			/* can_run */
    0,			/* notice_signals */
    dummy_stratum, 0,	/* stratum, next */
    0, 0, 0, 0, 0,	/* all mem, mem, stack, regs, exec */
    0, 0,		/* section pointers */
    OPS_MAGIC,
};

/* The target structure we are currently using to talk to a process
   or file or whatever "inferior" we have.  */

struct target_ops *current_target;

/* The stack of target structures that have been pushed.  */

struct target_ops **current_target_stack;

/* Command list for target.  */

static struct cmd_list_element *targetlist = NULL;

/* The user just typed 'target' without the name of a target.  */

/* ARGSUSED */
static void
target_command (arg, from_tty)
     char *arg;
     int from_tty;
{
  fputs_filtered ("Argument required (target name).  Try `help target'\n",
		  stdout);
}

/* Add a possible target architecture to the list.  */

void
add_target (t)
     struct target_ops *t;
{
  if (t->to_magic != OPS_MAGIC)
    {
      fprintf(stderr, "Magic number of %s target struct wrong\n", 
	t->to_shortname);
      abort();
    }

  if (!target_structs)
    {
      target_struct_allocsize = DEFAULT_ALLOCSIZE;
      target_structs = (struct target_ops **) xmalloc
	(target_struct_allocsize * sizeof (*target_structs));
    }
  if (target_struct_size >= target_struct_allocsize)
    {
      target_struct_allocsize *= 2;
      target_structs = (struct target_ops **)
	  xrealloc ((char *) target_structs, 
		    target_struct_allocsize * sizeof (*target_structs));
    }
  target_structs[target_struct_size++] = t;
  cleanup_target (t);

  if (targetlist == NULL)
    add_prefix_cmd ("target", class_run, target_command,
		    "Connect to a target machine or process.\n\
The first argument is the type or protocol of the target machine.\n\
Remaining arguments are interpreted by the target protocol.  For more\n\
information on the arguments for a particular protocol, type\n\
`help target ' followed by the protocol name.",
		    &targetlist, "target ", 0, &cmdlist);
  add_cmd (t->to_shortname, no_class, t->to_open, t->to_doc, &targetlist);
}

/* Stub functions */

static void
ignore ()
{
}

/* ARGSUSED */
static int
nomemory (memaddr, myaddr, len, write)
     CORE_ADDR memaddr;
     char *myaddr;
     int len;
     int write;
{
  errno = EIO;		/* Can't read/write this location */
  return 0;		/* No bytes handled */
}

static void
tcomplain ()
{
  error ("You can't do that when your target is `%s'",
	 current_target->to_shortname);
}

void
noprocess ()
{
  error ("You can't do that without a process to debug");
}

/* ARGSUSED */
static int
nosymbol (name, addrp)
     char *name;
     CORE_ADDR *addrp;
{
  return 1;		/* Symbol does not exist in target env */
}

/* ARGSUSED */
static void
default_terminal_info (args, from_tty)
     char *args;
     int from_tty;
{
  printf("No saved terminal information.\n");
}

#if 0
/* With strata, this function is no longer needed.  FIXME.  */
/* This is the default target_create_inferior function.  It looks up
   the stack for some target that cares to create inferiors, then
   calls it -- or complains if not found.  */

static void
upstack_create_inferior (exec, args, env)
     char *exec;
     char *args;
     char **env;
{
  struct target_ops *t;

  for (t = current_target;
       t;
       t = t->to_next)
    {
      if (t->to_create_inferior != upstack_create_inferior)
	{
          t->to_create_inferior (exec, args, env);
	  return;
	}

    }
  tcomplain();
}
#endif

/* This is the default target_create_inferior and target_attach function.
   If the current target is executing, it asks whether to kill it off.
   If this function returns without calling error(), it has killed off
   the target, and the operation should be attempted.  */

static void
kill_or_be_killed (from_tty)
     int from_tty;
{
  if (target_has_execution)
    {
      printf ("You are already running a program:\n");
      target_files_info ();
      if (query ("Kill it? ")) {
	target_kill ();
	if (target_has_execution)
	  error ("Killing the program did not help.");
	return;
      } else {
	error ("Program not killed.");
      }
    }
  tcomplain();
}

static void
maybe_kill_then_attach (args, from_tty)
     char *args;
     int from_tty;
{
  kill_or_be_killed (from_tty);
  target_attach (args, from_tty);
}

static void
maybe_kill_then_create_inferior (exec, args, env)
     char *exec;
     char *args;
     char **env;
{
  kill_or_be_killed (0);
  target_create_inferior (exec, args, env);
}

/* Clean up a target struct so it no longer has any zero pointers in it.
   We default entries, at least to stubs that print error messages.  */

static void
cleanup_target (t)
     struct target_ops *t;
{

  /* Check magic number.  If wrong, it probably means someone changed
     the struct definition, but not all the places that initialize one.  */
  if (t->to_magic != OPS_MAGIC)
    {
      fprintf(stderr, "Magic number of %s target struct wrong\n", 
	t->to_shortname);
      abort();
    }

#define de_fault(field, value) \
  if (!t->field)	t->field = value

  /*        FIELD			DEFAULT VALUE        */

  de_fault (to_open, 			(void (*)())tcomplain);
  de_fault (to_close, 			(void (*)())ignore);
  de_fault (to_attach, 			maybe_kill_then_attach);
  de_fault (to_detach, 			(void (*)())ignore);
  de_fault (to_resume, 			(void (*)())noprocess);
  de_fault (to_wait, 			(int (*)())noprocess);
  de_fault (to_fetch_registers, 	(void (*)())ignore);
  de_fault (to_store_registers,		(void (*)())noprocess);
  de_fault (to_prepare_to_store,	(void (*)())noprocess);
  de_fault (to_xfer_memory,		(int (*)())nomemory);
  de_fault (to_files_info,		(void (*)())ignore);
  de_fault (to_insert_breakpoint,	memory_insert_breakpoint);
  de_fault (to_remove_breakpoint,	memory_remove_breakpoint);
  de_fault (to_terminal_init,		ignore);
  de_fault (to_terminal_inferior,	ignore);
  de_fault (to_terminal_ours_for_output,ignore);
  de_fault (to_terminal_ours,		ignore);
  de_fault (to_terminal_info,		default_terminal_info);
  de_fault (to_kill,			(void (*)())noprocess);
  de_fault (to_load,			(void (*)())tcomplain);
  de_fault (to_lookup_symbol,		nosymbol);
  de_fault (to_create_inferior,		maybe_kill_then_create_inferior);
  de_fault (to_mourn_inferior,		(void (*)())noprocess);
  de_fault (to_can_run,			return_zero);
  de_fault (to_notice_signals,		(void (*)())ignore);
  de_fault (to_next,			0);
  de_fault (to_has_all_memory,		0);
  de_fault (to_has_memory,		0);
  de_fault (to_has_stack,		0);
  de_fault (to_has_registers,		0);
  de_fault (to_has_execution,		0);

#undef de_fault
}

/* Push a new target type into the stack of the existing target accessors,
   possibly superseding some of the existing accessors.