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path: root/libjava/classpath/java/security/SecureRandomSpi.java

/* Cache and manage frames for GDB, the GNU debugger.

   Copyright 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000,
   2001, 2002, 2003 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 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "frame.h"
#include "target.h"
#include "value.h"
#include "inferior.h"	/* for inferior_ptid */
#include "regcache.h"
#include "gdb_assert.h"
#include "gdb_string.h"
#include "builtin-regs.h"
#include "gdb_obstack.h"
#include "dummy-frame.h"
#include "sentinel-frame.h"
#include "gdbcore.h"
#include "annotate.h"
#include "language.h"
#include "frame-unwind.h"
#include "command.h"
#include "gdbcmd.h"

/* Flag to control debugging.  */

static int frame_debug;

/* Flag to indicate whether backtraces should stop at main.  */

static int backtrace_below_main;

/* Return a frame uniq ID that can be used to, later, re-find the
   frame.  */

struct frame_id
get_frame_id (struct frame_info *fi)
{
  if (fi == NULL)
    {
      return null_frame_id;
    }
  else
    {
      struct frame_id id;
      id.base = fi->frame;
      id.pc = fi->pc;
      return id;
    }
}

const struct frame_id null_frame_id; /* All zeros.  */

struct frame_id
frame_id_build (CORE_ADDR base, CORE_ADDR func_or_pc)
{
  struct frame_id id;
  id.base = base;
  id.pc = func_or_pc;
  return id;
}

int
frame_id_p (struct frame_id l)
{
  /* The .func can be NULL but the .base cannot.  */
  return (l.base != 0);
}

int
frame_id_eq (struct frame_id l, struct frame_id r)
{
  /* If .base is different, the frames are different.  */
  if (l.base != r.base)
    return 0;
  /* Add a test to check that the frame ID's are for the same function
     here.  */
  return 1;
}

int
frame_id_inner (struct frame_id l, struct frame_id r)
{
  /* Only return non-zero when strictly inner than.  Note that, per
     comment in "frame.h", there is some fuzz here.  Frameless
     functions are not strictly inner than (same .base but different
     .func).  */
  return INNER_THAN (l.base, r.base);
}

struct frame_info *
frame_find_by_id (struct frame_id id)
{
  struct frame_info *frame;

  /* ZERO denotes the null frame, let the caller decide what to do
     about it.  Should it instead return get_current_frame()?  */
  if (!frame_id_p (id))
    return NULL;

  for (frame = get_current_frame ();
       frame != NULL;
       frame = get_prev_frame (frame))
    {
      struct frame_id this = get_frame_id (frame);
      if (frame_id_eq (id, this))
	/* An exact match.  */
	return frame;
      if (frame_id_inner (id, this))
	/* Gone to far.  */
	return NULL;
      /* Either, we're not yet gone far enough out along the frame
         chain (inner(this,id), or we're comparing frameless functions
         (same .base, different .func, no test available).  Struggle
         on until we've definitly gone to far.  */
    }
  return NULL;
}

CORE_ADDR
frame_pc_unwind (struct frame_info *frame)
{
  if (!frame->pc_unwind_cache_p)
    {
      frame->pc_unwind_cache = frame->unwind->pc (frame, &frame->unwind_cache);
      frame->pc_unwind_cache_p = 1;
    }
  return frame->pc_unwind_cache;
}

struct frame_id
frame_id_unwind (struct frame_info *frame)
{
  if (!frame->id_unwind_cache_p)
    {
      frame->unwind->id (frame, &frame->unwind_cache, &frame->id_unwind_cache);
      frame->id_unwind_cache_p = 1;
    }
  return frame->id_unwind_cache;
}

void
frame_pop (struct frame_info *frame)
{
  /* FIXME: cagney/2003-01-18: There is probably a chicken-egg problem
     with passing in current_regcache.  The pop function needs to be
     written carefully so as to not overwrite registers whose [old]
     values are needed to restore other registers.  Instead, this code
     should pass in a scratch cache and, as a second step, restore the
     registers using that.  */
  frame->unwind->pop (frame, &frame->unwind_cache, current_regcache);
  flush_cached_frames ();
}

void
frame_register_unwind (struct frame_info *frame, int regnum,
		       int *optimizedp, enum lval_type *lvalp,
		       CORE_ADDR *addrp, int *realnump, void *bufferp)
{
  struct frame_unwind_cache *cache;

  /* Require all but BUFFERP to be valid.  A NULL BUFFERP indicates
     that the value proper does not need to be fetched.  */
  gdb_assert (optimizedp != NULL);
  gdb_assert (lvalp != NULL);
  gdb_assert (addrp != NULL);
  gdb_assert (realnump != NULL);
  /* gdb_assert (bufferp != NULL); */

  /* NOTE: cagney/2002-11-27: A program trying to unwind a NULL frame
     is broken.  There is always a frame.  If there, for some reason,
     isn't, there is some pretty busted code as it should have
     detected the problem before calling here.  */
  gdb_assert (frame != NULL);

  /* Ask this frame to unwind its register.  */
  frame->unwind->reg (frame, &frame->unwind_cache, regnum,
		      optimizedp, lvalp, addrp, realnump, bufferp);
}

void
frame_register (struct frame_info *frame, int regnum,
		int *optimizedp, enum lval_type *lvalp,
		CORE_ADDR *addrp, int *realnump, void *bufferp)
{
  /* Require all but BUFFERP to be valid.  A NULL BUFFERP indicates
     that the value proper does not need to be fetched.  */
  gdb_assert (optimizedp != NULL);
  gdb_assert (lvalp != NULL);
  gdb_assert (addrp != NULL);
  gdb_assert (realnump != NULL);
  /* gdb_assert (bufferp != NULL); */

  /* Ulgh!  Old code that, for lval_register, sets ADDRP to the offset
     of the register in the register cache.  It should instead return
     the REGNUM corresponding to that register.  Translate the .  */
  if (GET_SAVED_REGISTER_P ())
    {
      GET_SAVED_REGISTER (bufferp, optimizedp, addrp, frame, regnum, lvalp);
      /* Compute the REALNUM if the caller wants it.  */
      if (*lvalp == lval_register)
	{
	  int regnum;
	  for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++)
	    {
	      if (*addrp == register_offset_hack (current_gdbarch, regnum))
		{
		  *realnump = regnum;
		  return;
		}
	    }
	  internal_error (__FILE__, __LINE__,
			  "Failed to compute the register number corresponding"
			  " to 0x%s", paddr_d (*addrp));
	}
      *realnump = -1;
      return;
    }

  /* Obtain the register value by unwinding the register from the next
     (more inner frame).  */
  gdb_assert (frame != NULL && frame->next != NULL);
  frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
			 realnump, bufferp);
}

void
frame_unwind_register (struct frame_info *frame, int regnum, void *buf)
{
  int optimized;
  CORE_ADDR addr;
  int realnum;
  enum lval_type lval;
  frame_register_unwind (frame, regnum, &optimized, &lval, &addr,
			 &realnum, buf);
}

void
frame_unwind_signed_register (struct frame_info *frame, int regnum,
			      LONGEST *val)
{
  void *buf = alloca (MAX_REGISTER_RAW_SIZE);
  frame_unwind_register (frame, regnum, buf);
  (*val) = extract_signed_integer (buf, REGISTER_VIRTUAL_SIZE (regnum));
}

void
frame_unwind_unsigned_register (struct frame_info *frame, int regnum,
				ULONGEST *val)
{
  void *buf = alloca (MAX_REGISTER_RAW_SIZE);
  frame_unwind_register (frame, regnum, buf);
  (*val) = extract_unsigned_integer (buf, REGISTER_VIRTUAL_SIZE (regnum));
}

void
frame_read_register (struct frame_info *frame, int regnum, void *buf)
{
  gdb_assert (frame != NULL && frame->next != NULL);
  frame_unwind_register (frame->next, regnum, buf);
}

void
frame_read_unsigned_register (struct frame_info *frame, int regnum,
			      ULONGEST *val)
{
  /* NOTE: cagney/2002-10-31: There is a bit of dogma here - there is
     always a frame.  Both this, and the equivalent
     frame_read_signed_register() function, can only be called with a
     valid frame.  If, for some reason, this function is called
     without a frame then the problem isn't here, but rather in the
     caller.  It should of first created a frame and then passed that
     in.  */
  /* NOTE: cagney/2002-10-31: As a side bar, keep in mind that the
     ``current_frame'' should not be treated as a special case.  While
     ``get_next_frame (current_frame) == NULL'' currently holds, it
     should, as far as possible, not be relied upon.  In the future,
     ``get_next_frame (current_frame)'' may instead simply return a
     normal frame object that simply always gets register values from
     the register cache.  Consequently, frame code should try to avoid
     tests like ``if get_next_frame() == NULL'' and instead just rely
     on recursive frame calls (like the below code) when manipulating
     a frame chain.  */
  gdb_assert (frame != NULL && frame->next != NULL);
  frame_unwind_unsigned_register (frame->next, regnum, val);
}

void
frame_read_signed_register (struct frame_info *frame, int regnum,
			    LONGEST *val)
{
  /* See note above in frame_read_unsigned_register().  */
  gdb_assert (frame != NULL && frame->next != NULL);
  frame_unwind_signed_register (frame->next, regnum, val);
}

void
generic_unwind_get_saved_register (char *raw_buffer,
				   int *optimizedp,
				   CORE_ADDR *addrp,
				   struct frame_info *frame,
				   int regnum,
				   enum lval_type *lvalp)
{
  int optimizedx;
  CORE_ADDR addrx;
  int realnumx;
  enum lval_type lvalx;

  if (!target_has_registers)
    error ("No registers.");

  /* Keep things simple, ensure that all the pointers (except valuep)
     are non NULL.  */
  if (optimizedp == NULL)
    optimizedp = &optimizedx;
  if (lvalp == NULL)
    lvalp = &lvalx;
  if (addrp == NULL)
    addrp = &addrx;

  gdb_assert (frame != NULL && frame->next != NULL);
  frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
			 &realnumx, raw_buffer);
}

void
get_saved_register (char *raw_buffer,
		    int *optimized,
		    CORE_ADDR *addrp,
		    struct frame_info *frame,
		    int regnum,
		    enum lval_type *lval)
{
  if (GET_SAVED_REGISTER_P ())
    {
      GET_SAVED_REGISTER (raw_buffer, optimized, addrp, frame, regnum, lval);
      return;
    }
  generic_unwind_get_saved_register (raw_buffer, optimized, addrp, frame,
				     regnum, lval);
}

/* frame_register_read ()

   Find and return the value of REGNUM for the specified stack frame.
   The number of bytes copied is REGISTER_RAW_SIZE (REGNUM).

   Returns 0 if the register value could not be found.  */

int
frame_register_read (struct frame_info *frame, int regnum, void *myaddr)
{
  int optimized;
  enum lval_type lval;
  CORE_ADDR addr;
  int realnum;
  frame_register (frame, regnum, &optimized, &lval, &addr, &realnum, myaddr);

  /* FIXME: cagney/2002-05-15: This test, is just bogus.

     It indicates that the target failed to supply a value for a
     register because it was "not available" at this time.  Problem
     is, the target still has the register and so get saved_register()
     may be returning a value saved on the stack.  */

  if (register_cached (regnum) < 0)
    return 0;			/* register value not available */

  return !optimized;
}


/* Map between a frame register number and its name.  A frame register
   space is a superset of the cooked register space --- it also
   includes builtin registers.  */

int
frame_map_name_to_regnum (const char *name, int len)
{
  int i;

  if (len < 0)
    len = strlen (name);

  /* Search register name space. */
  for (i = 0; i < NUM_REGS + NUM_PSEUDO_REGS; i++)
    if (REGISTER_NAME (i) && len == strlen (REGISTER_NAME (i))
	&& strncmp (name, REGISTER_NAME (i), len) == 0)
      {
	return i;
      }

  /* Try builtin registers.  */
  i = builtin_reg_map_name_to_regnum (name, len);
  if (i >= 0)
    {
      /* A builtin register doesn't fall into the architecture's
         register range.  */
      gdb_assert (i >= NUM_REGS + NUM_PSEUDO_REGS);
      return i;
    }

  return -1;
}

const char *
frame_map_regnum_to_name (int regnum)
{
  if (regnum < 0)
    return NULL;
  if (regnum < NUM_REGS + NUM_PSEUDO_REGS)
    return REGISTER_NAME (regnum);
  return builtin_reg_map_regnum_to_name (regnum);
}

/* Create a sentinel frame.  */

struct frame_info *
create_sentinel_frame (struct regcache *regcache)
{
  struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
  frame->type = NORMAL_FRAME;
  frame->level = -1;
  /* Explicitly initialize the sentinel frame's cache.  Provide it
     with the underlying regcache.  In the future additional
     information, such as the frame's thread will be added.  */
  frame->unwind_cache = sentinel_frame_cache (regcache);
  /* For the moment there is only one sentinel frame implementation.  */
  frame->unwind = sentinel_frame_unwind;
  /* Link this frame back to itself.  The frame is self referential
     (the unwound PC is the same as the pc), so make it so.  */
  frame->next = frame;
  /* Always unwind the PC as part of creating this frame.  This
     ensures that the frame's PC points at something valid.  */
  /* FIXME: cagney/2003-01-10: Problem here.  Unwinding a sentinel
     frame's PC may require information such as the frame's thread's
     stop reason.  Is it possible to get to that?  */
  frame->pc = frame_pc_unwind (frame);
  return frame;
}

/* Info about the innermost stack frame (contents of FP register) */

static struct frame_info *current_frame;

/* Cache for frame addresses already read by gdb.  Valid only while
   inferior is stopped.  Control variables for the frame cache should
   be local to this module.  */

static struct obstack frame_cache_obstack;

void *
frame_obstack_zalloc (unsigned long size)
{
  void *data = obstack_alloc (&frame_cache_obstack, size);
  memset (data, 0, size);
  return data;
}

CORE_ADDR *
frame_saved_regs_zalloc (struct frame_info *fi)
{
  fi->saved_regs = (CORE_ADDR *)
    frame_obstack_zalloc (SIZEOF_FRAME_SAVED_REGS);
  return fi->saved_regs;
}

CORE_ADDR *
get_frame_saved_regs (struct frame_info *fi)
{
  return fi->saved_regs;
}

/* Return the innermost (currently executing) stack frame.  This is
   split into two functions.  The function unwind_to_current_frame()
   is wrapped in catch exceptions so that, even when the unwind of the
   sentinel frame fails, the function still returns a stack frame.  */

static int
unwind_to_current_frame (struct ui_out *ui_out, void *args)
{
  struct frame_info *frame = get_prev_frame (args);
  /* A sentinel frame can fail to unwind, eg, because it's PC value
     lands in somewhere like start.  */
  if (frame == NULL)
    return 1;
  current_frame = frame;
  return 0;
}

struct frame_info *
get_current_frame (void)
{
  if (!target_has_stack)
    error ("No stack.");
  if (!target_has_registers)
    error ("No registers.");
  if (!target_has_memory)
    error ("No memory.");
  if (current_frame == NULL)
    {
      struct frame_info *sentinel_frame =
	create_sentinel_frame (current_regcache);
      if (catch_exceptions (uiout, unwind_to_current_frame, sentinel_frame,
			    NULL, RETURN_MASK_ERROR) != 0)
	{
	  /* Oops! Fake a current frame?  Is this useful?  It has a PC
             of zero, for instance.  */
	  current_frame = sentinel_frame;
	}
    }
  return current_frame;
}

/* The "selected" stack frame is used by default for local and arg
   access.  May be zero, for no selected frame.  */

struct frame_info *deprecated_selected_frame;

/* Return the selected frame.  Always non-null (unless there isn't an
   inferior sufficient for creating a frame) in which case an error is
   thrown.  */

struct frame_info *
get_selected_frame (void)
{
  if (deprecated_selected_frame == NULL)
    /* Hey!  Don't trust this.  It should really be re-finding the
       last selected frame of the currently selected thread.  This,
       though, is better than nothing.  */
    select_frame (get_current_frame ());
  /* There is always a frame.  */
  gdb_assert (deprecated_selected_frame != NULL);
  return deprecated_selected_frame;
}

/* Select frame FI (or NULL - to invalidate the current frame).  */

void
select_frame (struct frame_info *fi)
{
  register struct symtab *s;

  deprecated_selected_frame = fi;
  /* NOTE: cagney/2002-05-04: FI can be NULL.  This occures when the
     frame is being invalidated.  */
  if (selected_frame_level_changed_hook)
    selected_frame_level_changed_hook (frame_relative_level (fi));

  /* FIXME: kseitz/2002-08-28: It would be nice to call
     selected_frame_level_changed_event right here, but due to limitations
     in the current interfaces, we would end up flooding UIs with events
     because select_frame is used extensively internally.

     Once we have frame-parameterized frame (and frame-related) commands,
     the event notification can be moved here, since this function will only
     be called when the users selected frame is being changed. */

  /* Ensure that symbols for this frame are read in.  Also, determine the
     source language of this frame, and switch to it if desired.  */
  if (fi)
    {
      s = find_pc_symtab (fi->pc);
      if (s
	  && s->language != current_language->la_language
	  && s->language != language_unknown
	  && language_mode == language_mode_auto)
	{
	  set_language (s->language);
	}
    }
}

/* Return the register saved in the simplistic ``saved_regs'' cache.
   If the value isn't here AND a value is needed, try the next inner
   most frame.  */

static void
frame_saved_regs_register_unwind (struct frame_info *frame, void **cache,
				  int regnum, int *optimizedp,
				  enum lval_type *lvalp, CORE_ADDR *addrp,
				  int *realnump, void *bufferp)
{
  /* There is always a frame at this point.  And THIS is the frame
     we're interested in.  */
  gdb_assert (frame != NULL);
  /* If we're using generic dummy frames, we'd better not be in a call
     dummy.  (generic_call_dummy_register_unwind ought to have been called
     instead.)  */
  gdb_assert (!(DEPRECATED_USE_GENERIC_DUMMY_FRAMES
		&& (get_frame_type (frame) == DUMMY_FRAME)));

  /* Only (older) architectures that implement the
     DEPRECATED_FRAME_INIT_SAVED_REGS method should be using this
     function.  */
  gdb_assert (DEPRECATED_FRAME_INIT_SAVED_REGS_P ());

  /* Load the saved_regs register cache.  */
  if (get_frame_saved_regs (frame) == NULL)
    DEPRECATED_FRAME_INIT_SAVED_REGS (frame);

  if (get_frame_saved_regs (frame) != NULL
      && get_frame_saved_regs (frame)[regnum] != 0)
    {
      if (regnum == SP_REGNUM)
	{
	  /* SP register treated specially.  */
	  *optimizedp = 0;
	  *lvalp = not_lval;
	  *addrp = 0;
	  *realnump = -1;
	  if (bufferp != NULL)
	    store_address (bufferp, REGISTER_RAW_SIZE (regnum),
			   get_frame_saved_regs (frame)[regnum]);
	}
      else
	{
	  /* Any other register is saved in memory, fetch it but cache
             a local copy of its value.  */
	  *optimizedp = 0;
	  *lvalp = lval_memory;
	  *addrp = get_frame_saved_regs (frame)[regnum];
	  *realnump = -1;
	  if (bufferp != NULL)
	    {
#if 1
	      /* Save each register value, as it is read in, in a
                 frame based cache.  */
	      void **regs = (*cache);
	      if (regs == NULL)
		{
		  int sizeof_cache = ((NUM_REGS + NUM_PSEUDO_REGS)
				      * sizeof (void *));
		  regs = frame_obstack_zalloc (sizeof_cache);
		  (*cache) = regs;
		}
	      if (regs[regnum] == NULL)
		{
		  regs[regnum]
		    = frame_obstack_zalloc (REGISTER_RAW_SIZE (regnum));
		  read_memory (get_frame_saved_regs (frame)[regnum], regs[regnum],
			       REGISTER_RAW_SIZE (regnum));
		}
	      memcpy (bufferp, regs[regnum], REGISTER_RAW_SIZE (regnum));
#else
	      /* Read the value in from memory.  */
	      read_memory (get_frame_saved_regs (frame)[regnum], bufferp,
			   REGISTER_RAW_SIZE (regnum));
#endif
	    }
	}
      return;
    }

  /* No luck, assume this and the next frame have the same register
     value.  Pass the request down the frame chain to the next frame.
     Hopefully that will find the register's location, either in a
     register or in memory.  */
  frame_register (frame, regnum, optimizedp, lvalp, addrp, realnump,
		  bufferp);
}

static CORE_ADDR
frame_saved_regs_pc_unwind (struct frame_info *frame, void **cache)
{
  gdb_assert (FRAME_SAVED_PC_P ());
  return FRAME_SAVED_PC (frame);
}
	
static void
frame_saved_regs_id_unwind (struct frame_info *next_frame, void **cache,
			    struct frame_id *id)
{
  int fromleaf;
  CORE_ADDR base;
  CORE_ADDR pc;

  /* Start out by assuming it's NULL.  */
  (*id) = null_frame_id;

  if (frame_relative_level (next_frame) <= 0)
    /* FIXME: 2002-11-09: Frameless functions can occure anywhere in
       the frame chain, not just the inner most frame!  The generic,
       per-architecture, frame code should handle this and the below
       should simply be removed.  */
    fromleaf = FRAMELESS_FUNCTION_INVOCATION (next_frame);
  else
    fromleaf = 0;

  if (fromleaf)
    /* A frameless inner-most frame.  The `FP' (which isn't an
       architecture frame-pointer register!) of the caller is the same