gdb/remote.c

/* Remote target communications for serial-line targets in custom GDB protocol

   Copyright (C) 1988-2016 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/>.  */

/* See the GDB User Guide for details of the GDB remote protocol.  */

#include "defs.h"
#include <ctype.h>
#include <fcntl.h>
#include "inferior.h"
#include "infrun.h"
#include "bfd.h"
#include "symfile.h"
#include "target.h"
/*#include "terminal.h" */
#include "gdbcmd.h"
#include "objfiles.h"
#include "gdb-stabs.h"
#include "gdbthread.h"
#include "remote.h"
#include "remote-notif.h"
#include "regcache.h"
#include "value.h"
#include "observer.h"
#include "solib.h"
#include "cli/cli-decode.h"
#include "cli/cli-setshow.h"
#include "target-descriptions.h"
#include "gdb_bfd.h"
#include "filestuff.h"
#include "rsp-low.h"
#include "disasm.h"
#include "location.h"

#include "gdb_sys_time.h"

#include "event-loop.h"
#include "event-top.h"
#include "inf-loop.h"

#include <signal.h>
#include "serial.h"

#include "gdbcore.h" /* for exec_bfd */

#include "remote-fileio.h"
#include "gdb/fileio.h"
#include <sys/stat.h>
#include "xml-support.h"

#include "memory-map.h"

#include "tracepoint.h"
#include "ax.h"
#include "ax-gdb.h"
#include "agent.h"
#include "btrace.h"

/* Temp hacks for tracepoint encoding migration.  */
static char *target_buf;
static long target_buf_size;

/* Per-program-space data key.  */
static const struct program_space_data *remote_pspace_data;

/* The variable registered as the control variable used by the
   remote exec-file commands.  While the remote exec-file setting is
   per-program-space, the set/show machinery uses this as the 
   location of the remote exec-file value.  */
static char *remote_exec_file_var;

/* The size to align memory write packets, when practical.  The protocol
   does not guarantee any alignment, and gdb will generate short
   writes and unaligned writes, but even as a best-effort attempt this
   can improve bulk transfers.  For instance, if a write is misaligned
   relative to the target's data bus, the stub may need to make an extra
   round trip fetching data from the target.  This doesn't make a
   huge difference, but it's easy to do, so we try to be helpful.

   The alignment chosen is arbitrary; usually data bus width is
   important here, not the possibly larger cache line size.  */
enum { REMOTE_ALIGN_WRITES = 16 };

/* Prototypes for local functions.  */
static int getpkt_sane (char **buf, long *sizeof_buf, int forever);
static int getpkt_or_notif_sane (char **buf, long *sizeof_buf,
				 int forever, int *is_notif);

static void remote_files_info (struct target_ops *ignore);

static void remote_prepare_to_store (struct target_ops *self,
				     struct regcache *regcache);

static void remote_open_1 (const char *, int, struct target_ops *,
			   int extended_p);

static void remote_close (struct target_ops *self);

struct remote_state;

static int remote_vkill (int pid, struct remote_state *rs);

static void remote_kill_k (void);

static void remote_mourn (struct target_ops *ops);

static void extended_remote_restart (void);

static void remote_send (char **buf, long *sizeof_buf_p);

static int readchar (int timeout);

static void remote_serial_write (const char *str, int len);

static void remote_kill (struct target_ops *ops);

static int remote_can_async_p (struct target_ops *);

static int remote_is_async_p (struct target_ops *);

static void remote_async (struct target_ops *ops, int enable);

static void remote_thread_events (struct target_ops *ops, int enable);

static void interrupt_query (void);

static void set_general_thread (struct ptid ptid);
static void set_continue_thread (struct ptid ptid);

static void get_offsets (void);

static void skip_frame (void);

static long read_frame (char **buf_p, long *sizeof_buf);

static int hexnumlen (ULONGEST num);

static void init_remote_ops (void);

static void init_extended_remote_ops (void);

static void remote_stop (struct target_ops *self, ptid_t);

static int stubhex (int ch);

static int hexnumstr (char *, ULONGEST);

static int hexnumnstr (char *, ULONGEST, int);

static CORE_ADDR remote_address_masked (CORE_ADDR);

static void print_packet (const char *);

static void compare_sections_command (char *, int);

static void packet_command (char *, int);

static int stub_unpack_int (char *buff, int fieldlength);

static ptid_t remote_current_thread (ptid_t oldptid);

static int putpkt_binary (const char *buf, int cnt);

static void check_binary_download (CORE_ADDR addr);

struct packet_config;

static void show_packet_config_cmd (struct packet_config *config);

static void show_remote_protocol_packet_cmd (struct ui_file *file,
					     int from_tty,
					     struct cmd_list_element *c,
					     const char *value);

static char *write_ptid (char *buf, const char *endbuf, ptid_t ptid);
static ptid_t read_ptid (char *buf, char **obuf);

static void remote_set_permissions (struct target_ops *self);

static int remote_get_trace_status (struct target_ops *self,
				    struct trace_status *ts);

static int remote_upload_tracepoints (struct target_ops *self,
				      struct uploaded_tp **utpp);

static int remote_upload_trace_state_variables (struct target_ops *self,
						struct uploaded_tsv **utsvp);
  
static void remote_query_supported (void);

static void remote_check_symbols (void);

void _initialize_remote (void);

struct stop_reply;
static void stop_reply_xfree (struct stop_reply *);
static void remote_parse_stop_reply (char *, struct stop_reply *);
static void push_stop_reply (struct stop_reply *);
static void discard_pending_stop_replies_in_queue (struct remote_state *);
static int peek_stop_reply (ptid_t ptid);

struct threads_listing_context;
static void remove_new_fork_children (struct threads_listing_context *);

static void remote_async_inferior_event_handler (gdb_client_data);

static void remote_terminal_ours (struct target_ops *self);

static int remote_read_description_p (struct target_ops *target);

static void remote_console_output (char *msg);

static int remote_supports_cond_breakpoints (struct target_ops *self);

static int remote_can_run_breakpoint_commands (struct target_ops *self);

static void remote_btrace_reset (void);

static int stop_reply_queue_length (void);

static void readahead_cache_invalidate (void);

static void remote_unpush_and_throw (void);

/* For "remote".  */

static struct cmd_list_element *remote_cmdlist;

/* For "set remote" and "show remote".  */

static struct cmd_list_element *remote_set_cmdlist;
static struct cmd_list_element *remote_show_cmdlist;

/* Stub vCont actions support.

   Each field is a boolean flag indicating whether the stub reports
   support for the corresponding action.  */

struct vCont_action_support
{
  /* vCont;t */
  int t;

  /* vCont;r */
  int r;

  /* vCont;s */
  int s;

  /* vCont;S */
  int S;
};

/* Controls whether GDB is willing to use range stepping.  */

static int use_range_stepping = 1;

#define OPAQUETHREADBYTES 8

/* a 64 bit opaque identifier */
typedef unsigned char threadref[OPAQUETHREADBYTES];

/* About this many threadisds fit in a packet.  */

#define MAXTHREADLISTRESULTS 32

/* Data for the vFile:pread readahead cache.  */

struct readahead_cache
{
  /* The file descriptor for the file that is being cached.  -1 if the
     cache is invalid.  */
  int fd;

  /* The offset into the file that the cache buffer corresponds
     to.  */
  ULONGEST offset;

  /* The buffer holding the cache contents.  */
  gdb_byte *buf;
  /* The buffer's size.  We try to read as much as fits into a packet
     at a time.  */
  size_t bufsize;

  /* Cache hit and miss counters.  */
  ULONGEST hit_count;
  ULONGEST miss_count;
};

/* Description of the remote protocol state for the currently
   connected target.  This is per-target state, and independent of the
   selected architecture.  */

struct remote_state
{
  /* A buffer to use for incoming packets, and its current size.  The
     buffer is grown dynamically for larger incoming packets.
     Outgoing packets may also be constructed in this buffer.
     BUF_SIZE is always at least REMOTE_PACKET_SIZE;
     REMOTE_PACKET_SIZE should be used to limit the length of outgoing
     packets.  */
  char *buf;
  long buf_size;

  /* True if we're going through initial connection setup (finding out
     about the remote side's threads, relocating symbols, etc.).  */
  int starting_up;

  /* If we negotiated packet size explicitly (and thus can bypass
     heuristics for the largest packet size that will not overflow
     a buffer in the stub), this will be set to that packet size.
     Otherwise zero, meaning to use the guessed size.  */
  long explicit_packet_size;

  /* remote_wait is normally called when the target is running and
     waits for a stop reply packet.  But sometimes we need to call it
     when the target is already stopped.  We can send a "?" packet
     and have remote_wait read the response.  Or, if we already have
     the response, we can stash it in BUF and tell remote_wait to
     skip calling getpkt.  This flag is set when BUF contains a
     stop reply packet and the target is not waiting.  */
  int cached_wait_status;

  /* True, if in no ack mode.  That is, neither GDB nor the stub will
     expect acks from each other.  The connection is assumed to be
     reliable.  */
  int noack_mode;

  /* True if we're connected in extended remote mode.  */
  int extended;

  /* True if we resumed the target and we're waiting for the target to
     stop.  In the mean time, we can't start another command/query.
     The remote server wouldn't be ready to process it, so we'd
     timeout waiting for a reply that would never come and eventually
     we'd close the connection.  This can happen in asynchronous mode
     because we allow GDB commands while the target is running.  */
  int waiting_for_stop_reply;

  /* The status of the stub support for the various vCont actions.  */
  struct vCont_action_support supports_vCont;

  /* Nonzero if the user has pressed Ctrl-C, but the target hasn't
     responded to that.  */
  int ctrlc_pending_p;

  /* True if we saw a Ctrl-C while reading or writing from/to the
     remote descriptor.  At that point it is not safe to send a remote
     interrupt packet, so we instead remember we saw the Ctrl-C and
     process it once we're done with sending/receiving the current
     packet, which should be shortly.  If however that takes too long,
     and the user presses Ctrl-C again, we offer to disconnect.  */
  int got_ctrlc_during_io;

  /* Descriptor for I/O to remote machine.  Initialize it to NULL so that
     remote_open knows that we don't have a file open when the program
     starts.  */
  struct serial *remote_desc;

  /* These are the threads which we last sent to the remote system.  The
     TID member will be -1 for all or -2 for not sent yet.  */
  ptid_t general_thread;
  ptid_t continue_thread;

  /* This is the traceframe which we last selected on the remote system.
     It will be -1 if no traceframe is selected.  */
  int remote_traceframe_number;

  char *last_pass_packet;

  /* The last QProgramSignals packet sent to the target.  We bypass
     sending a new program signals list down to the target if the new
     packet is exactly the same as the last we sent.  IOW, we only let
     the target know about program signals list changes.  */
  char *last_program_signals_packet;

  enum gdb_signal last_sent_signal;

  int last_sent_step;

  /* The execution direction of the last resume we got.  */
  enum exec_direction_kind last_resume_exec_dir;

  char *finished_object;
  char *finished_annex;
  ULONGEST finished_offset;

  /* Should we try the 'ThreadInfo' query packet?

     This variable (NOT available to the user: auto-detect only!)
     determines whether GDB will use the new, simpler "ThreadInfo"
     query or the older, more complex syntax for thread queries.
     This is an auto-detect variable (set to true at each connect,
     and set to false when the target fails to recognize it).  */
  int use_threadinfo_query;
  int use_threadextra_query;

  threadref echo_nextthread;
  threadref nextthread;
  threadref resultthreadlist[MAXTHREADLISTRESULTS];

  /* The state of remote notification.  */
  struct remote_notif_state *notif_state;

  /* The branch trace configuration.  */
  struct btrace_config btrace_config;

  /* The argument to the last "vFile:setfs:" packet we sent, used
     to avoid sending repeated unnecessary "vFile:setfs:" packets.
     Initialized to -1 to indicate that no "vFile:setfs:" packet
     has yet been sent.  */
  int fs_pid;

  /* A readahead cache for vFile:pread.  Often, reading a binary
     involves a sequence of small reads.  E.g., when parsing an ELF
     file.  A readahead cache helps mostly the case of remote
     debugging on a connection with higher latency, due to the
     request/reply nature of the RSP.  We only cache data for a single
     file descriptor at a time.  */
  struct readahead_cache readahead_cache;
};

/* Private data that we'll store in (struct thread_info)->private.  */
struct private_thread_info
{
  char *extra;
  char *name;
  int core;

  /* Whether the target stopped for a breakpoint/watchpoint.  */
  enum target_stop_reason stop_reason;

  /* This is set to the data address of the access causing the target
     to stop for a watchpoint.  */
  CORE_ADDR watch_data_address;
};

static void
free_private_thread_info (struct private_thread_info *info)
{
  xfree (info->extra);
  xfree (info->name);
  xfree (info);
}

/* This data could be associated with a target, but we do not always
   have access to the current target when we need it, so for now it is
   static.  This will be fine for as long as only one target is in use
   at a time.  */
static struct remote_state *remote_state;

static struct remote_state *
get_remote_state_raw (void)
{
  return remote_state;
}

/* Allocate a new struct remote_state with xmalloc, initialize it, and
   return it.  */

static struct remote_state *
new_remote_state (void)
{
  struct remote_state *result = XCNEW (struct remote_state);

  /* The default buffer size is unimportant; it will be expanded
     whenever a larger buffer is needed. */
  result->buf_size = 400;
  result->buf = (char *) xmalloc (result->buf_size);
  result->remote_traceframe_number = -1;
  result->last_sent_signal = GDB_SIGNAL_0;
  result->last_resume_exec_dir = EXEC_FORWARD;
  result->fs_pid = -1;

  return result;
}

/* Description of the remote protocol for a given architecture.  */

struct packet_reg
{
  long offset; /* Offset into G packet.  */
  long regnum; /* GDB's internal register number.  */
  LONGEST pnum; /* Remote protocol register number.  */
  int in_g_packet; /* Always part of G packet.  */
  /* long size in bytes;  == register_size (target_gdbarch (), regnum);
     at present.  */
  /* char *name; == gdbarch_register_name (target_gdbarch (), regnum);
     at present.  */
};

struct remote_arch_state
{
  /* Description of the remote protocol registers.  */
  long sizeof_g_packet;

  /* Description of the remote protocol registers indexed by REGNUM
     (making an array gdbarch_num_regs in size).  */
  struct packet_reg *regs;

  /* This is the size (in chars) of the first response to the ``g''
     packet.  It is used as a heuristic when determining the maximum
     size of memory-read and memory-write packets.  A target will
     typically only reserve a buffer large enough to hold the ``g''
     packet.  The size does not include packet overhead (headers and
     trailers).  */
  long actual_register_packet_size;

  /* This is the maximum size (in chars) of a non read/write packet.
     It is also used as a cap on the size of read/write packets.  */
  long remote_packet_size;
};

/* Utility: generate error from an incoming stub packet.  */
static void
trace_error (char *buf)
{
  if (*buf++ != 'E')
    return;			/* not an error msg */
  switch (*buf)
    {
    case '1':			/* malformed packet error */
      if (*++buf == '0')	/*   general case: */
	error (_("remote.c: error in outgoing packet."));
      else
	error (_("remote.c: error in outgoing packet at field #%ld."),
	       strtol (buf, NULL, 16));
    default:
      error (_("Target returns error code '%s'."), buf);
    }
}

/* Utility: wait for reply from stub, while accepting "O" packets.  */
static char *
remote_get_noisy_reply (char **buf_p,
			long *sizeof_buf)
{
  do				/* Loop on reply from remote stub.  */
    {
      char *buf;

      QUIT;			/* Allow user to bail out with ^C.  */
      getpkt (buf_p, sizeof_buf, 0);
      buf = *buf_p;
      if (buf[0] == 'E')
	trace_error (buf);
      else if (startswith (buf, "qRelocInsn:"))
	{
	  ULONGEST ul;
	  CORE_ADDR from, to, org_to;
	  char *p, *pp;
	  int adjusted_size = 0;
	  int relocated = 0;

	  p = buf + strlen ("qRelocInsn:");
	  pp = unpack_varlen_hex (p, &ul);
	  if (*pp != ';')
	    error (_("invalid qRelocInsn packet: %s"), buf);
	  from = ul;

	  p = pp + 1;
	  unpack_varlen_hex (p, &ul);
	  to = ul;

	  org_to = to;

	  TRY
	    {
	      gdbarch_relocate_instruction (target_gdbarch (), &to, from);
	      relocated = 1;
	    }
	  CATCH (ex, RETURN_MASK_ALL)
	    {
	      if (ex.error == MEMORY_ERROR)
		{
		  /* Propagate memory errors silently back to the
		     target.  The stub may have limited the range of
		     addresses we can write to, for example.  */
		}
	      else
		{
		  /* Something unexpectedly bad happened.  Be verbose
		     so we can tell what, and propagate the error back
		     to the stub, so it doesn't get stuck waiting for
		     a response.  */
		  exception_fprintf (gdb_stderr, ex,
				     _("warning: relocating instruction: "));
		}
	      putpkt ("E01");
	    }
	  END_CATCH

	  if (relocated)
	    {
	      adjusted_size = to - org_to;

	      xsnprintf (buf, *sizeof_buf, "qRelocInsn:%x", adjusted_size);
	      putpkt (buf);
	    }
	}
      else if (buf[0] == 'O' && buf[1] != 'K')
	remote_console_output (buf + 1);	/* 'O' message from stub */
      else
	return buf;		/* Here's the actual reply.  */
    }
  while (1);
}

/* Handle for retreving the remote protocol data from gdbarch.  */
static struct gdbarch_data *remote_gdbarch_data_handle;

static struct remote_arch_state *
get_remote_arch_state (void)
{
  gdb_assert (target_gdbarch () != NULL);
  return ((struct remote_arch_state *)
	  gdbarch_data (target_gdbarch (), remote_gdbarch_data_handle));
}

/* Fetch the global remote target state.  */

static struct remote_state *
get_remote_state (void)
{
  /* Make sure that the remote architecture state has been
     initialized, because doing so might reallocate rs->buf.  Any
     function which calls getpkt also needs to be mindful of changes
     to rs->buf, but this call limits the number of places which run
     into trouble.  */
  get_remote_arch_state ();

  return get_remote_state_raw ();
}

/* Cleanup routine for the remote module's pspace data.  */

static void
remote_pspace_data_cleanup (struct program_space *pspace, void *arg)
{
  char *remote_exec_file = (char *) arg;

  xfree (remote_exec_file);
}

/* Fetch the remote exec-file from the current program space.  */

static const char *
get_remote_exec_file (void)
{
  char *remote_exec_file;

  remote_exec_file
    = (char *) program_space_data (current_program_space,
				   remote_pspace_data);
  if (remote_exec_file == NULL)
    return "";

  return remote_exec_file;
}

/* Set the remote exec file for PSPACE.  */

static void
set_pspace_remote_exec_file (struct program_space *pspace,
			char *remote_exec_file)
{
  char *old_file = (char *) program_space_data (pspace, remote_pspace_data);

  xfree (old_file);
  set_program_space_data (pspace, remote_pspace_data,
			  xstrdup (remote_exec_file));
}

/* The "set/show remote exec-file" set command hook.  */

static void
set_remote_exec_file (char *ignored, int from_tty,
		      struct cmd_list_element *c)
{
  gdb_assert (remote_exec_file_var != NULL);
  set_pspace_remote_exec_file (current_program_space, remote_exec_file_var);
}

/* The "set/show remote exec-file" show command hook.  */

static void
show_remote_exec_file (struct ui_file *file, int from_tty,
		       struct cmd_list_element *cmd, const char *value)
{
  fprintf_filtered (file, "%s\n", remote_exec_file_var);
}

static int
compare_pnums (const void *lhs_, const void *rhs_)
{
  const struct packet_reg * const *lhs
    = (const struct packet_reg * const *) lhs_;
  const struct packet_reg * const *rhs
    = (const struct packet_reg * const *) rhs_;

  if ((*lhs)->pnum < (*rhs)->pnum)
    return -1;
  else if ((*lhs)->pnum == (*rhs)->pnum)
    return 0;
  else
    return 1;
}

static int
map_regcache_remote_table (struct gdbarch *gdbarch, struct packet_reg *regs)
{
  int regnum, num_remote_regs, offset;
  struct packet_reg **remote_regs;

  for (regnum = 0; regnum < gdbarch_num_regs (gdbarch); regnum++)
    {
      struct packet_reg *r = &regs[regnum];

      if (register_size (gdbarch, regnum) == 0)
	/* Do not try to fetch zero-sized (placeholder) registers.  */
	r->pnum = -1;
      else
	r->pnum = gdbarch_remote_register_number (gdbarch, regnum);

      r->regnum = regnum;
    }

  /* Define the g/G packet format as the contents of each register
     with a remote protocol number, in order of ascending protocol
     number.  */

  remote_regs = XALLOCAVEC (struct packet_reg *, gdbarch_num_regs (gdbarch));
  for (num_remote_regs = 0, regnum = 0;
       regnum < gdbarch_num_regs (gdbarch);
       regnum++)
    if (regs[regnum].pnum != -1)
      remote_regs[num_remote_regs++] = &regs[regnum];

  qsort (remote_regs, num_remote_regs, sizeof (struct packet_reg *),
	 compare_pnums);

  for (regnum = 0, offset = 0; regnum < num_remote_regs; regnum++)
    {
      remote_regs[regnum]->in_g_packet = 1;
      remote_regs[regnum]->offset = offset;
      offset += register_size (gdbarch, remote_regs[regnum]->regnum);
    }

  return offset;
}

/* Given the architecture described by GDBARCH, return the remote
   protocol register's number and the register's offset in the g/G
   packets of GDB register REGNUM, in PNUM and POFFSET respectively.
   If the target does not have a mapping for REGNUM, return false,
   otherwise, return true.  */

int
remote_register_number_and_offset (struct gdbarch *gdbarch, int regnum,
				   int *pnum, int *poffset)
{
  struct packet_reg *regs;
  struct cleanup *old_chain;

  gdb_assert (regnum < gdbarch_num_regs (gdbarch));

  regs = XCNEWVEC (struct packet_reg, gdbarch_num_regs (gdbarch));
  old_chain = make_cleanup (xfree, regs);

  map_regcache_remote_table (gdbarch, regs);

  *pnum = regs[regnum].pnum;
  *poffset = regs[regnum].offset;

  do_cleanups (old_chain);

  return *pnum != -1;
}

static void *
init_remote_state (struct gdbarch *gdbarch)
{
  struct remote_state *rs = get_remote_state_raw ();
  struct remote_arch_state *rsa;

  rsa = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct remote_arch_state);

  /* Use the architecture to build a regnum<->pnum table, which will be
     1:1 unless a feature set specifies otherwise.  */
  rsa->regs = GDBARCH_OBSTACK_CALLOC (gdbarch,
				      gdbarch_num_regs (gdbarch),
				      struct packet_reg);

  /* Record the maximum possible size of the g packet - it may turn out
     to be smaller.  */
  rsa->sizeof_g_packet = map_regcache_remote_table (gdbarch, rsa->regs);

  /* Default maximum number of characters in a packet body.  Many
     remote stubs have a hardwired buffer size of 400 bytes
     (c.f. BUFMAX in m68k-stub.c and i386-stub.c).  BUFMAX-1 is used
     as the maximum packet-size to ensure that the packet and an extra
     NUL character can always fit in the buffer.  This stops GDB
     trashing stubs that try to squeeze an extra NUL into what is
     already a full buffer (As of 1999-12-04 that was most stubs).  */
  rsa->remote_packet_size = 400 - 1;

  /* This one is filled in when a ``g'' packet is received.  */
  rsa->actual_register_packet_size = 0;

  /* Should rsa->sizeof_g_packet needs more space than the
     default, adjust the size accordingly.  Remember that each byte is
     encoded as two characters.  32 is the overhead for the packet
     header / footer.  NOTE: cagney/1999-10-26: I suspect that 8
     (``$NN:G...#NN'') is a better guess, the below has been padded a
     little.  */
  if (rsa->sizeof_g_packet > ((rsa->remote_packet_size - 32) / 2))
    rsa->remote_packet_size = (rsa->sizeof_g_packet * 2 + 32);

  /* Make sure that the packet buffer is plenty big enough for
     this architecture.  */
  if (rs->buf_size < rsa->remote_packet_size)
    {
      rs->buf_size = 2 * rsa->remote_packet_size;
      rs->buf = (char *) xrealloc (rs->buf, rs->buf_size);
    }

  return rsa;
}

/* Return the current allowed size of a remote packet.  This is
   inferred from the current architecture, and should be used to
   limit the length of outgoing packets.  */
static long
get_remote_packet_size (void)
{
  struct remote_state *rs = get_remote_state ();
  struct remote_arch_state *rsa = get_remote_arch_state ();

  if (rs->explicit_packet_size)
    return rs->explicit_packet_size;

  return rsa->remote_packet_size;
}

static struct packet_reg *
packet_reg_from_regnum (struct remote_arch_state *rsa, long regnum)
{
  if (regnum < 0 && regnum >= gdbarch_num_regs (target_gdbarch ()))
    return NULL;
  else
    {
      struct packet_reg *r = &rsa->regs[regnum];

      gdb_assert (r->regnum == regnum);
      return r;
    }
}

static struct packet_reg *
packet_reg_from_pnum (struct remote_arch_state *rsa, LONGEST pnum)
{
  int i;

  for (i = 0; i < gdbarch_num_regs (target_gdbarch ()); i++)
    {
      struct packet_reg *r = &rsa->regs[i];

      if (r->pnum == pnum)
	return r;
    }
  return NULL;
}

static struct target_ops remote_ops;

static struct target_ops extended_remote_ops;

/* FIXME: cagney/1999-09-23: Even though getpkt was called with
   ``forever'' still use the normal timeout mechanism.  This is
   currently used by the ASYNC code to guarentee that target reads
   during the initial connect always time-out.  Once getpkt has been
   modified to return a timeout indication and, in turn
   remote_wait()/wait_for_inferior() have gained a timeout parameter
   this can go away.  */
static int wait_forever_enabled_p = 1;

/* Allow the user to specify what sequence to send to the remote
   when he requests a program interruption: Although ^C is usually
   what remote systems expect (this is the default, here), it is
   sometimes preferable to send a break.  On other systems such
   as the Linux kernel, a break followed by g, which is Magic SysRq g
   is required in order to interrupt the execution.  */
const char interrupt_sequence_control_c[] = "Ctrl-C";
const char interrupt_sequence_break[] = "BREAK";
const char interrupt_sequence_break_g[] = "BREAK-g";
static const char *const interrupt_sequence_modes[] =
  {
    interrupt_sequence_control_c,
    interrupt_sequence_break,
    interrupt_sequence_break_g,
    NULL
  };
static const char *interrupt_sequence_mode = interrupt_sequence_control_c;

static void
show_interrupt_sequence (struct ui_file *file, int from_tty,
			 struct cmd_list_element *c,
			 const char *value)
{
  if (interrupt_sequence_mode == interrupt_sequence_control_c)
    fprintf_filtered (file,
		      _("Send the ASCII ETX character (Ctrl-c) "
			"to the remote target to interrupt the "
			"execution of the program.\n"));
  else if (interrupt_sequence_mode == interrupt_sequence_break)
    fprintf_filtered (file,
		      _("send a break signal to the remote target "
			"to interrupt the execution of the program.\n"));
  else if (interrupt_sequence_mode == interrupt_sequence_break_g)
    fprintf_filtered (file,
		      _("Send a break signal and 'g' a.k.a. Magic SysRq g to "
			"the remote target to interrupt the execution "
			"of Linux kernel.\n"));
  else
    internal_error (__FILE__, __LINE__,
		    _("Invalid value for interrupt_sequence_mode: %s."),
		    interrupt_sequence_mode);
}

/* This boolean variable specifies whether interrupt_sequence is sent
   to the remote target when gdb connects to it.
   This is mostly needed when you debug the Linux kernel: The Linux kernel
   expects BREAK g which is Magic SysRq g for connecting gdb.  */
static int interrupt_on_connect = 0;

/* This variable is used to implement the "set/show remotebreak" commands.
   Since these commands are now deprecated in favor of "set/show remote
   interrupt-sequence", it no longer has any effect on the code.  */
static int remote_break;

static void
set_remotebreak (char *args, int from_tty, struct cmd_list_element *c)
{
  if (remote_break)
    interrupt_sequence_mode = interrupt_sequence_break;
  else
    interrupt_sequence_mode = interrupt_sequence_control_c;
}

static void
show_remotebreak (struct ui_file *file, int from_tty,
		  struct cmd_list_element *c,
		  const char *value)
{
}

/* This variable sets the number of bits in an address that are to be
   sent in a memory ("M" or "m") packet.  Normally, after stripping
   leading zeros, the entire address would be sent.  This variable
   restricts the address to REMOTE_ADDRESS_SIZE bits.  HISTORY: The
   initial implementation of remote.c restricted the address sent in
   memory packets to ``host::sizeof long'' bytes - (typically 32
   bits).  Consequently, for 64 bit targets, the upper 32 bits of an
   address was never sent.  Since fixing this bug may cause a break in
   some remote targets this variable is principly provided to
   facilitate backward compatibility.  */

static unsigned int remote_address_size;

/* Temporary to track who currently owns the terminal.  See
   remote_terminal_* for more details.  */

static int remote_async_terminal_ours_p;


/* User configurable variables for the number of characters in a
   memory read/write packet.  MIN (rsa->remote_packet_size,
   rsa->sizeof_g_packet) is the default.  Some targets need smaller
   values (fifo overruns, et.al.) and some users need larger values
   (speed up transfers).  The variables ``preferred_*'' (the user
   request), ``current_*'' (what was actually set) and ``forced_*''
   (Positive - a soft limit, negative - a hard limit).  */

struct memory_packet_config
{
  char *name;
  long size;
  int fixed_p;
};

/* The default max memory-write-packet-size.  The 16k is historical.
   (It came from older GDB's using alloca for buffers and the
   knowledge (folklore?) that some hosts don't cope very well with
   large alloca calls.)  */
#define DEFAULT_MAX_MEMORY_PACKET_SIZE 16384

/* The minimum remote packet size for memory transfers.  Ensures we
   can write at least one byte.  */
#define MIN_MEMORY_PACKET_SIZE 20

/* Compute the current size of a read/write packet.  Since this makes
   use of ``actual_register_packet_size'' the computation is dynamic.  */

static long
get_memory_packet_size (struct memory_packet_config *config)
{
  struct remote_state *rs = get_remote_state ();
  struct remote_arch_state *rsa = get_remote_arch_state ();

  long what_they_get;
  if (config->fixed_p)
    {
      if (config->size <= 0)
	what_they_get = DEFAULT_MAX_MEMORY_PACKET_SIZE;
      else
	what_they_get = config->size;
    }
  else
    {
      what_they_get = get_remote_packet_size ();
      /* Limit the packet to the size specified by the user.  */
      if (config->size > 0
	  && what_they_get > config->size)
	what_they_get = config->size;

      /* Limit it to the size of the targets ``g'' response unless we have
	 permission from the stub to use a larger packet size.  */
      if (rs->explicit_packet_size == 0
	  && rsa->actual_register_packet_size > 0
	  && what_they_get > rsa->actual_register_packet_size)
	what_they_get = rsa->actual_register_packet_size;
    }
  if (what_they_get < MIN_MEMORY_PACKET_SIZE)
    what_they_get = MIN_MEMORY_PACKET_SIZE;

  /* Make sure there is room in the global buffer for this packet
     (including its trailing NUL byte).  */
  if (rs->buf_size < what_they_get + 1)
    {
      rs->buf_size = 2 * what_they_get;
      rs->buf = (char *) xrealloc (rs->buf, 2 * what_they_get);
    }

  return what_they_get;
}

/* Update the size of a read/write packet.  If they user wants
   something really big then do a sanity check.  */

static void
set_memory_packet_size (char *args, struct memory_packet_config *config)
{
  int fixed_p = config->fixed_p;
  long size = config->size;

  if (args == NULL)
    error (_("Argument required (integer, `fixed' or `limited')."));
  else if (strcmp (args, "hard") == 0
      || strcmp (args, "fixed") == 0)
    fixed_p = 1;
  else if (strcmp (args, "soft") == 0
	   || strcmp (args, "limit") == 0)
    fixed_p = 0;
  else
    {
      char *end;

      size = strtoul (args, &end, 0);
      if (args == end)
	error (_("Invalid %s (bad syntax)."), config->name);

      /* Instead of explicitly capping the size of a packet to or
	 disallowing it, the user is allowed to set the size to
	 something arbitrarily large.  */
    }

  /* So that the query shows the correct value.  */
  if (size <= 0)
    size = DEFAULT_MAX_MEMORY_PACKET_SIZE;

  /* Extra checks?  */
  if (fixed_p && !config->fixed_p)
    {
      if (! query (_("The target may not be able to correctly handle a %s\n"
		   "of %ld bytes. Change the packet size? "),
		   config->name, size))
	error (_("Packet size not changed."));
    }
  /* Update the config.  */
  config->fixed_p = fixed_p;
  config->size = size;
}

static void
show_memory_packet_size (struct memory_packet_config *config)
{
  printf_filtered (_("The %s is %ld. "), config->name, config->size);
  if (config->fixed_p)
    printf_filtered (_("Packets are fixed at %ld bytes.\n"),
		     get_memory_packet_size (config));
  else
    printf_filtered (_("Packets are limited to %ld bytes.\n"),
		     get_memory_packet_size (config));
}

static struct memory_packet_config memory_write_packet_config =
{
  "memory-write-packet-size",
};

static void
set_memory_write_packet_size (char *args, int from_tty)
{
  set_memory_packet_size (args, &memory_write_packet_config);
}

static void
show_memory_write_packet_size (char *args, int from_tty)
{
  show_memory_packet_size (&memory_write_packet_config);
}

static long
get_memory_write_packet_size (void)
{
  return get_memory_packet_size (&memory_write_packet_config);
}

static struct memory_packet_config memory_read_packet_config =
{
  "memory-read-packet-size",
};

static void
set_memory_read_packet_size (char *args, int from_tty)
{
  set_memory_packet_size (args, &memory_read_packet_config);
}

static void
show_memory_read_packet_size (char *args, int from_tty)
{
  show_memory_packet_size (&memory_read_packet_config);
}

static long
get_memory_read_packet_size (void)
{
  long size = get_memory_packet_size (&memory_read_packet_config);

  /* FIXME: cagney/1999-11-07: Functions like getpkt() need to get an
     extra buffer size argument before the memory read size can be
     increased beyond this.  */
  if (size > get_remote_packet_size ())
    size = get_remote_packet_size ();
  return size;
}


/* Generic configuration support for packets the stub optionally
   supports.  Allows the user to specify the use of the packet as well
   as allowing GDB to auto-detect support in the remote stub.  */

enum packet_support
  {
    PACKET_SUPPORT_UNKNOWN = 0,
    PACKET_ENABLE,
    PACKET_DISABLE
  };

struct packet_config
  {
    const char *name;
    const char *title;

    /* If auto, GDB auto-detects support for this packet or feature,
       either through qSupported, or by trying the packet and looking
       at the response.  If true, GDB assumes the target supports this
       packet.  If false, the packet is disabled.  Configs that don't
       have an associated command always have this set to auto.  */
    enum auto_boolean detect;

    /* Does the target support this packet?  */
    enum packet_support support;
  };

/* Analyze a packet's return value and update the packet config
   accordingly.  */

enum packet_result
{
  PACKET_ERROR,
  PACKET_OK,
  PACKET_UNKNOWN
};

static enum packet_support packet_config_support (struct packet_config *config);
static enum packet_support packet_support (int packet);

static void
show_packet_config_cmd (struct packet_config *config)
{
  char *support = "internal-error";

  switch (packet_config_support (config))
    {
    case PACKET_ENABLE:
      support = "enabled";
      break;
    case PACKET_DISABLE:
      support = "disabled";
      break;
    case PACKET_SUPPORT_UNKNOWN:
      support = "unknown";
      break;
    }
  switch (config->detect)
    {
    case AUTO_BOOLEAN_AUTO:
      printf_filtered (_("Support for the `%s' packet "
			 "is auto-detected, currently %s.\n"),
		       config->name, support);
      break;
    case AUTO_BOOLEAN_TRUE:
    case AUTO_BOOLEAN_FALSE:
      printf_filtered (_("Support for the `%s' packet is currently %s.\n"),
		       config->name, support);
      break;
    }
}

static void
add_packet_config_cmd (struct packet_config *config, const char *name,
		       const char *title, int legacy)
{
  char *set_doc;
  char *show_doc;
  char *cmd_name;

  config->name = name;
  config->title = title;
  set_doc = xstrprintf ("Set use of remote protocol `%s' (%s) packet",
			name, title);
  show_doc = xstrprintf ("Show current use of remote "
			 "protocol `%s' (%s) packet",
			 name, title);
  /* set/show TITLE-packet {auto,on,off} */
  cmd_name = xstrprintf ("%s-packet", title);
  add_setshow_auto_boolean_cmd (cmd_name, class_obscure,
				&config->detect, set_doc,
				show_doc, NULL, /* help_doc */
				NULL,
				show_remote_protocol_packet_cmd,
				&remote_set_cmdlist, &remote_show_cmdlist);
  /* The command code copies the documentation strings.  */
  xfree (set_doc);
  xfree (show_doc);
  /* set/show remote NAME-packet {auto,on,off} -- legacy.  */
  if (legacy)
    {
      char *legacy_name;

      legacy_name = xstrprintf ("%s-packet", name);
      add_alias_cmd (legacy_name, cmd_name, class_obscure, 0,
		     &remote_set_cmdlist);
      add_alias_cmd (legacy_name, cmd_name, class_obscure, 0,
		     &remote_show_cmdlist);
    }
}

static enum packet_result
packet_check_result (const char *buf)
{
  if (buf[0] != '\0')
    {
      /* The stub recognized the packet request.  Check that the
	 operation succeeded.  */
      if (buf[0] == 'E'
	  && isxdigit (buf[1]) && isxdigit (buf[2])
	  && buf[3] == '\0')
	/* "Enn"  - definitly an error.  */
	return PACKET_ERROR;

      /* Always treat "E." as an error.  This will be used for
	 more verbose error messages, such as E.memtypes.  */
      if (buf[0] == 'E' && buf[1] == '.')
	return PACKET_ERROR;

      /* The packet may or may not be OK.  Just assume it is.  */
      return PACKET_OK;
    }
  else
    /* The stub does not support the packet.  */
    return PACKET_UNKNOWN;
}

static enum packet_result
packet_ok (const char *buf, struct packet_config *config)
{
  enum packet_result result;

  if (config->detect != AUTO_BOOLEAN_TRUE
      && config->support == PACKET_DISABLE)
    internal_error (__FILE__, __LINE__,
		    _("packet_ok: attempt to use a disabled packet"));

  result = packet_check_result (buf);
  switch (result)
    {
    case PACKET_OK:
    case PACKET_ERROR:
      /* The stub recognized the packet request.  */
      if (config->support == PACKET_SUPPORT_UNKNOWN)
	{
	  if (remote_debug)
	    fprintf_unfiltered (gdb_stdlog,
				"Packet %s (%s) is supported\n",
				config->name, config->title);
	  config->support = PACKET_ENABLE;
	}
      break;
    case PACKET_UNKNOWN:
      /* The stub does not support the packet.  */
      if (config->detect == AUTO_BOOLEAN_AUTO
	  && config->support == PACKET_ENABLE)
	{
	  /* If the stub previously indicated that the packet was
	     supported then there is a protocol error.  */
	  error (_("Protocol error: %s (%s) conflicting enabled responses."),
		 config->name, config->title);
	}
      else if (config->detect == AUTO_BOOLEAN_TRUE)
	{
	  /* The user set it wrong.  */
	  error (_("Enabled packet %s (%s) not recognized by stub"),
		 config->name, config->title);
	}

      if (remote_debug)
	fprintf_unfiltered (gdb_stdlog,
			    "Packet %s (%s) is NOT supported\n",
			    config->name, config->title);
      config->support = PACKET_DISABLE;
      break;
    }

  return result;
}

enum {
  PACKET_vCont = 0,
  PACKET_X,
  PACKET_qSymbol,
  PACKET_P,
  PACKET_p,
  PACKET_Z0,
  PACKET_Z1,
  PACKET_Z2,
  PACKET_Z3,
  PACKET_Z4,
  PACKET_vFile_setfs,
  PACKET_vFile_open,
  PACKET_vFile_pread,
  PACKET_vFile_pwrite,
  PACKET_vFile_close,
  PACKET_vFile_unlink,
  PACKET_vFile_readlink,
  PACKET_vFile_fstat,
  PACKET_qXfer_auxv,
  PACKET_qXfer_features,
  PACKET_qXfer_exec_file,
  PACKET_qXfer_libraries,
  PACKET_qXfer_libraries_svr4,
  PACKET_qXfer_memory_map,
  PACKET_qXfer_spu_read,
  PACKET_qXfer_spu_write,
  PACKET_qXfer_osdata,
  PACKET_qXfer_threads,
  PACKET_qXfer_statictrace_read,
  PACKET_qXfer_traceframe_info,
  PACKET_qXfer_uib,
  PACKET_qGetTIBAddr,
  PACKET_qGetTLSAddr,
  PACKET_qSupported,
  PACKET_qTStatus,
  PACKET_QPassSignals,
  PACKET_QCatchSyscalls,
  PACKET_QProgramSignals,
  PACKET_qCRC,
  PACKET_qSearch_memory,
  PACKET_vAttach,
  PACKET_vRun,
  PACKET_QStartNoAckMode,
  PACKET_vKill,
  PACKET_qXfer_siginfo_read,
  PACKET_qXfer_siginfo_write,
  PACKET_qAttached,

  /* Support for conditional tracepoints.  */
  PACKET_ConditionalTracepoints,

  /* Support for target-side breakpoint conditions.  */
  PACKET_ConditionalBreakpoints,

  /* Support for target-side breakpoint commands.  */
  PACKET_BreakpointCommands,

  /* Support for fast tracepoints.  */
  PACKET_FastTracepoints,

  /* Support for static tracepoints.  */
  PACKET_StaticTracepoints,

  /* Support for installing tracepoints while a trace experiment is
     running.  */
  PACKET_InstallInTrace,

  PACKET_bc,
  PACKET_bs,
  PACKET_TracepointSource,
  PACKET_QAllow,
  PACKET_qXfer_fdpic,
  PACKET_QDisableRandomization,
  PACKET_QAgent,
  PACKET_QTBuffer_size,
  PACKET_Qbtrace_off,
  PACKET_Qbtrace_bts,
  PACKET_Qbtrace_pt,
  PACKET_qXfer_btrace,

  /* Support for the QNonStop packet.  */
  PACKET_QNonStop,

  /* Support for the QThreadEvents packet.  */
  PACKET_QThreadEvents,

  /* Support for multi-process extensions.  */
  PACKET_multiprocess_feature,

  /* Support for enabling and disabling tracepoints while a trace
     experiment is running.  */
  PACKET_EnableDisableTracepoints_feature,

  /* Support for collecting strings using the tracenz bytecode.  */
  PACKET_tracenz_feature,

  /* Support for continuing to run a trace experiment while GDB is
     disconnected.  */
  PACKET_DisconnectedTracing_feature,

  /* Support for qXfer:libraries-svr4:read with a non-empty annex.  */
  PACKET_augmented_libraries_svr4_read_feature,

  /* Support for the qXfer:btrace-conf:read packet.  */
  PACKET_qXfer_btrace_conf,

  /* Support for the Qbtrace-conf:bts:size packet.  */
  PACKET_Qbtrace_conf_bts_size,

  /* Support for swbreak+ feature.  */
  PACKET_swbreak_feature,

  /* Support for hwbreak+ feature.  */
  PACKET_hwbreak_feature,

  /* Support for fork events.  */
  PACKET_fork_event_feature,

  /* Support for vfork events.  */
  PACKET_vfork_event_feature,

  /* Support for the Qbtrace-conf:pt:size packet.  */
  PACKET_Qbtrace_conf_pt_size,

  /* Support for exec events.  */
  PACKET_exec_event_feature,

  /* Support for query supported vCont actions.  */
  PACKET_vContSupported,

  /* Support remote CTRL-C.  */
  PACKET_vCtrlC,

  /* Support TARGET_WAITKIND_NO_RESUMED.  */
  PACKET_no_resumed,

  PACKET_MAX
};

static struct packet_config remote_protocol_packets[PACKET_MAX];

/* Returns the packet's corresponding "set remote foo-packet" command
   state.  See struct packet_config for more details.  */

static enum auto_boolean
packet_set_cmd_state (int packet)
{
  return remote_protocol_packets[packet].detect;
}

/* Returns whether a given packet or feature is supported.  This takes
   into account the state of the corresponding "set remote foo-packet"
   command, which may be used to bypass auto-detection.  */

static enum packet_support
packet_config_support (struct packet_config *config)
{
  switch (config->detect)
    {
    case AUTO_BOOLEAN_TRUE:
      return PACKET_ENABLE;
    case AUTO_BOOLEAN_FALSE:
      return PACKET_DISABLE;
    case AUTO_BOOLEAN_AUTO:
      return config->support;
    default:
      gdb_assert_not_reached (_("bad switch"));
    }
}

/* Same as packet_config_support, but takes the packet's enum value as
   argument.  */

static enum packet_support
packet_support (int packet)
{
  struct packet_config *config = &remote_protocol_packets[packet];

  return packet_config_support (config);
}

static void
show_remote_protocol_packet_cmd (struct ui_file *file, int from_tty,
				 struct cmd_list_element *c,
				 const char *value)
{
  struct packet_config *packet;

  for (packet = remote_protocol_packets;
       packet < &remote_protocol_packets[PACKET_MAX];
       packet++)
    {
      if (&packet->detect == c->var)
	{
	  show_packet_config_cmd (packet);
	  return;
	}
    }
  internal_error (__FILE__, __LINE__, _("Could not find config for %s"),
		  c->name);
}

/* Should we try one of the 'Z' requests?  */

enum Z_packet_type
{
  Z_PACKET_SOFTWARE_BP,
  Z_PACKET_HARDWARE_BP,
  Z_PACKET_WRITE_WP,
  Z_PACKET_READ_WP,
  Z_PACKET_ACCESS_WP,
  NR_Z_PACKET_TYPES
};

/* For compatibility with older distributions.  Provide a ``set remote
   Z-packet ...'' command that updates all the Z packet types.  */

static enum auto_boolean remote_Z_packet_detect;

static void
set_remote_protocol_Z_packet_cmd (char *args, int from_tty,
				  struct cmd_list_element *c)
{
  int i;

  for (i = 0; i < NR_Z_PACKET_TYPES; i++)
    remote_protocol_packets[PACKET_Z0 + i].detect = remote_Z_packet_detect;
}

static void
show_remote_protocol_Z_packet_cmd (struct ui_file *file, int from_tty,
				   struct cmd_list_element *c,
				   const char *value)
{
  int i;

  for (i = 0; i < NR_Z_PACKET_TYPES; i++)
    {
      show_packet_config_cmd (&remote_protocol_packets[PACKET_Z0 + i]);
    }
}

/* Returns true if the multi-process extensions are in effect.  */

static int
remote_multi_process_p (struct remote_state *rs)
{
  return packet_support (PACKET_multiprocess_feature) == PACKET_ENABLE;
}

/* Returns true if fork events are supported.  */

static int
remote_fork_event_p (struct remote_state *rs)
{
  return packet_support (PACKET_fork_event_feature) == PACKET_ENABLE;
}

/* Returns true if vfork events are supported.  */

static int
remote_vfork_event_p (struct remote_state *rs)
{
  return packet_support (PACKET_vfork_event_feature) == PACKET_ENABLE;
}

/* Returns true if exec events are supported.  */

static int
remote_exec_event_p (struct remote_state *rs)
{
  return packet_support (PACKET_exec_event_feature) == PACKET_ENABLE;
}

/* Insert fork catchpoint target routine.  If fork events are enabled
   then return success, nothing more to do.  */

static int
remote_insert_fork_catchpoint (struct target_ops *ops, int pid)
{
  struct remote_state *rs = get_remote_state ();

  return !remote_fork_event_p (rs);
}

/* Remove fork catchpoint target routine.  Nothing to do, just
   return success.  */

static int
remote_remove_fork_catchpoint (struct target_ops *ops, int pid)
{
  return 0;
}

/* Insert vfork catchpoint target routine.  If vfork events are enabled
   then return success, nothing more to do.  */

static int
remote_insert_vfork_catchpoint (struct target_ops *ops, int pid)
{
  struct remote_state *rs = get_remote_state ();

  return !remote_vfork_event_p (rs);
}

/* Remove vfork catchpoint target routine.  Nothing to do, just
   return success.  */

static int
remote_remove_vfork_catchpoint (struct target_ops *ops, int pid)
{
  return 0;
}

/* Insert exec catchpoint target routine.  If exec events are
   enabled, just return success.  */

static int
remote_insert_exec_catchpoint (struct target_ops *ops, int pid)
{
  struct remote_state *rs = get_remote_state ();

  return !remote_exec_event_p (rs);
}

/* Remove exec catchpoint target routine.  Nothing to do, just
   return success.  */

static int
remote_remove_exec_catchpoint (struct target_ops *ops, int pid)
{
  return 0;
}


/* Asynchronous signal handle registered as event loop source for
   when we have pending events ready to be passed to the core.  */

static struct async_event_handler *remote_async_inferior_event_token;



static ptid_t magic_null_ptid;
static ptid_t not_sent_ptid;
static ptid_t any_thread_ptid;

/* Find out if the stub attached to PID (and hence GDB should offer to
   detach instead of killing it when bailing out).  */

static int
remote_query_attached (int pid)
{
  struct remote_state *rs = get_remote_state ();
  size_t size = get_remote_packet_size ();

  if (packet_support (PACKET_qAttached) == PACKET_DISABLE)
    return 0;

  if (remote_multi_process_p (rs))
    xsnprintf (rs->buf, size, "qAttached:%x", pid);
  else
    xsnprintf (rs->buf, size, "qAttached");

  putpkt (rs->buf);
  getpkt (&rs->buf, &rs->buf_size, 0);

  switch (packet_ok (rs->buf,
		     &remote_protocol_packets[PACKET_qAttached]))
    {
    case PACKET_OK:
      if (strcmp (rs->buf, "1") == 0)
	return 1;
      break;
    case PACKET_ERROR:
      warning (_("Remote failure reply: %s"), rs->buf);
      break;
    case PACKET_UNKNOWN:
      break;
    }

  return 0;
}

/* Add PID to GDB's inferior table.  If FAKE_PID_P is true, then PID
   has been invented by GDB, instead of reported by the target.  Since
   we can be connected to a remote system before before knowing about
   any inferior, mark the target with execution when we find the first
   inferior.  If ATTACHED is 1, then we had just attached to this
   inferior.  If it is 0, then we just created this inferior.  If it
   is -1, then try querying the remote stub to find out if it had
   attached to the inferior or not.  If TRY_OPEN_EXEC is true then
   attempt to open this inferior's executable as the main executable
   if no main executable is open already.  */

static struct inferior *
remote_add_inferior (int fake_pid_p, int pid, int attached,
		     int try_open_exec)
{
  struct inferior *inf;

  /* Check whether this process we're learning about is to be
     considered attached, or if is to be considered to have been
     spawned by the stub.  */
  if (attached == -1)
    attached = remote_query_attached (pid);

  if (gdbarch_has_global_solist (target_gdbarch ()))
    {
      /* If the target shares code across all inferiors, then every
	 attach adds a new inferior.  */
      inf = add_inferior (pid);

      /* ... and every inferior is bound to the same program space.
	 However, each inferior may still have its own address
	 space.  */
      inf->aspace = maybe_new_address_space ();
      inf->pspace = current_program_space;
    }
  else
    {
      /* In the traditional debugging scenario, there's a 1-1 match
	 between program/address spaces.  We simply bind the inferior
	 to the program space's address space.  */
      inf = current_inferior ();
      inferior_appeared (inf, pid);
    }

  inf->attach_flag = attached;
  inf->fake_pid_p = fake_pid_p;

  /* If no main executable is currently open then attempt to
     open the file that was executed to create this inferior.  */
  if (try_open_exec && get_exec_file (0) == NULL)
    exec_file_locate_attach (pid, 1);

  return inf;
}

/* Add thread PTID to GDB's thread list.  Tag it as executing/running
   according to RUNNING.  */

static void
remote_add_thread (ptid_t ptid, int running, int executing)
{
  struct remote_state *rs = get_remote_state ();

  /* GDB historically didn't pull threads in the initial connection
     setup.  If the remote target doesn't even have a concept of
     threads (e.g., a bare-metal target), even if internally we
     consider that a single-threaded target, mentioning a new thread
     might be confusing to the user.  Be silent then, preserving the
     age old behavior.  */
  if (rs->starting_up)
    add_thread_silent (ptid);
  else
    add_thread (ptid);

  set_executing (ptid, executing);
  set_running (ptid, running);
}

/* Come here when we learn about a thread id from the remote target.
   It may be the first time we hear about such thread, so take the
   opportunity to add it to GDB's thread list.  In case this is the
   first time we're noticing its corresponding inferior, add it to
   GDB's inferior list as well.  EXECUTING indicates whether the
   thread is (internally) executing or stopped.  */

static void
remote_notice_new_inferior (ptid_t currthread, int executing)
{
  /* In non-stop mode, we assume new found threads are (externally)
     running until proven otherwise with a stop reply.  In all-stop,
     we can only get here if all threads are stopped.  */
  int running = target_is_non_stop_p () ? 1 : 0;

  /* If this is a new thread, add it to GDB's thread list.
     If we leave it up to WFI to do this, bad things will happen.  */

  if (in_thread_list (currthread) && is_exited (currthread))
    {
      /* We're seeing an event on a thread id we knew had exited.
	 This has to be a new thread reusing the old id.  Add it.  */
      remote_add_thread (currthread, running, executing);
      return;
    }

  if (!in_thread_list (currthread))
    {
      struct inferior *inf = NULL;
      int pid = ptid_get_pid (currthread);

      if (ptid_is_pid (inferior_ptid)
	  && pid == ptid_get_pid (inferior_ptid))
	{
	  /* inferior_ptid has no thread member yet.  This can happen
	     with the vAttach -> remote_wait,"TAAthread:" path if the
	     stub doesn't support qC.  This is the first stop reported
	     after an attach, so this is the main thread.  Update the
	     ptid in the thread list.  */
	  if (in_thread_list (pid_to_ptid (pid)))
	    thread_change_ptid (inferior_ptid, currthread);
	  else
	    {
	      remote_add_thread (currthread, running, executing);
	      inferior_ptid = currthread;
	    }
	  return;
	}

      if (ptid_equal (magic_null_ptid, inferior_ptid))
	{
	  /* inferior_ptid is not set yet.  This can happen with the
	     vRun -> remote_wait,"TAAthread:" path if the stub
	     doesn't support qC.  This is the first stop reported
	     after an attach, so this is the main thread.  Update the
	     ptid in the thread list.  */
	  thread_change_ptid (inferior_ptid, currthread);
	  return;
	}

      /* When connecting to a target remote, or to a target
	 extended-remote which already was debugging an inferior, we
	 may not know about it yet.  Add it before adding its child
	 thread, so notifications are emitted in a sensible order.  */
      if (!in_inferior_list (ptid_get_pid (currthread)))
	{
	  struct remote_state *rs = get_remote_state ();
	  int fake_pid_p = !remote_multi_process_p (rs);

	  inf = remote_add_inferior (fake_pid_p,
				     ptid_get_pid (currthread), -1, 1);
	}

      /* This is really a new thread.  Add it.  */
      remote_add_thread (currthread, running, executing);

      /* If we found a new inferior, let the common code do whatever
	 it needs to with it (e.g., read shared libraries, insert
	 breakpoints), unless we're just setting up an all-stop
	 connection.  */
      if (inf != NULL)
	{
	  struct remote_state *rs = get_remote_state ();

	  if (!rs->starting_up)
	    notice_new_inferior (currthread, executing, 0);
	}
    }
}

/* Return the private thread data, creating it if necessary.  */

static struct private_thread_info *
demand_private_info (ptid_t ptid)
{
  struct thread_info *info = find_thread_ptid (ptid);

  gdb_assert (info);

  if (!info->priv)
    {
      info->priv = XNEW (struct private_thread_info);
      info->private_dtor = free_private_thread_info;
      info->priv->core = -1;
      info->priv->extra = NULL;
      info->priv->name = NULL;
    }

  return info->priv;
}

/* Call this function as a result of
   1) A halt indication (T packet) containing a thread id
   2) A direct query of currthread
   3) Successful execution of set thread */

static void
record_currthread (struct remote_state *rs, ptid_t currthread)
{
  rs->general_thread = currthread;
}

/* If 'QPassSignals' is supported, tell the remote stub what signals
   it can simply pass through to the inferior without reporting.  */

static void
remote_pass_signals (struct target_ops *self,
		     int numsigs, unsigned char *pass_signals)
{
  if (packet_support (PACKET_QPassSignals) != PACKET_DISABLE)
    {
      char *pass_packet, *p;
      int count = 0, i;
      struct remote_state *rs = get_remote_state ();

      gdb_assert (numsigs < 256);
      for (i = 0; i < numsigs; i++)
	{
	  if (pass_signals[i])
	    count++;
	}
      pass_packet = (char *) xmalloc (count * 3 + strlen ("QPassSignals:") + 1);
      strcpy (pass_packet, "QPassSignals:");
      p = pass_packet + strlen (pass_packet);
      for (i = 0; i < numsigs; i++)
	{
	  if (pass_signals[i])
	    {
	      if (i >= 16)
		*p++ = tohex (i >> 4);
	      *p++ = tohex (i & 15);
	      if (count)
		*p++ = ';';
	      else
		break;
	      count--;
	    }
	}
      *p = 0;
      if (!rs->last_pass_packet || strcmp (rs->last_pass_packet, pass_packet))
	{
	  putpkt (pass_packet);
	  getpkt (&rs->buf, &rs->buf_size, 0);
	  packet_ok (rs->buf, &remote_protocol_packets[PACKET_QPassSignals]);
	  if (rs->last_pass_packet)
	    xfree (rs->last_pass_packet);
	  rs->last_pass_packet = pass_packet;
	}
      else
	xfree (pass_packet);
    }
}

/* If 'QCatchSyscalls' is supported, tell the remote stub
   to report syscalls to GDB.  */

static int
remote_set_syscall_catchpoint (struct target_ops *self,
			       int pid, int needed, int any_count,
			       int table_size, int *table)
{
  char *catch_packet;
  enum packet_result result;
  int n_sysno = 0;

  if (packet_support (PACKET_QCatchSyscalls) == PACKET_DISABLE)
    {
      /* Not supported.  */
      return 1;
    }

  if (needed && !any_count)
    {
      int i;

      /* Count how many syscalls are to be caught (table[sysno] != 0).  */
      for (i = 0; i < table_size; i++)
	{
	  if (table[i] != 0)
	    n_sysno++;
	}
    }

  if (remote_debug)
    {
      fprintf_unfiltered (gdb_stdlog,
			  "remote_set_syscall_catchpoint "
			  "pid %d needed %d any_count %d n_sysno %d\n",
			  pid, needed, any_count, n_sysno);
    }

  if (needed)
    {
      /* Prepare a packet with the sysno list, assuming max 8+1
	 characters for a sysno.  If the resulting packet size is too
	 big, fallback on the non-selective packet.  */
      const int maxpktsz = strlen ("QCatchSyscalls:1") + n_sysno * 9 + 1;

      catch_packet = (char *) xmalloc (maxpktsz);
      strcpy (catch_packet, "QCatchSyscalls:1");
      if (!any_count)
	{
	  int i;
	  char *p;

	  p = catch_packet;
	  p += strlen (p);

	  /* Add in catch_packet each syscall to be caught (table[i] != 0).  */
	  for (i = 0; i < table_size; i++)
	    {
	      if (table[i] != 0)
		p += xsnprintf (p, catch_packet + maxpktsz - p, ";%x", i);
	    }
	}
      if (strlen (catch_packet) > get_remote_packet_size ())
	{
	  /* catch_packet too big.  Fallback to less efficient
	     non selective mode, with GDB doing the filtering.  */
	  catch_packet[sizeof ("QCatchSyscalls:1") - 1] = 0;
	}
    }
  else
    catch_packet = xstrdup ("QCatchSyscalls:0");

  {
    struct cleanup *old_chain = make_cleanup (xfree, catch_packet);
    struct remote_state *rs = get_remote_state ();

    putpkt (catch_packet);
    getpkt (&rs->buf, &rs->buf_size, 0);
    result = packet_ok (rs->buf, &remote_protocol_packets[PACKET_QCatchSyscalls]);
    do_cleanups (old_chain);
    if (result == PACKET_OK)
      return 0;
    else
      return -1;
  }
}

/* If 'QProgramSignals' is supported, tell the remote stub what
   signals it should pass through to the inferior when detaching.  */

static void
remote_program_signals (struct target_ops *self,
			int numsigs, unsigned char *signals)
{
  if (packet_support (PACKET_QProgramSignals) != PACKET_DISABLE)
    {
      char *packet, *p;
      int count = 0, i;
      struct remote_state *rs = get_remote_state ();

      gdb_assert (numsigs < 256);
      for (i = 0; i < numsigs; i++)
	{
	  if (signals[i])
	    count++;
	}
      packet = (char *) xmalloc (count * 3 + strlen ("QProgramSignals:") + 1);
      strcpy (packet, "QProgramSignals:");
      p = packet + strlen (packet);
      for (i = 0; i < numsigs; i++)
	{
	  if (signal_pass_state (i))
	    {
	      if (i >= 16)
		*p++ = tohex (i >> 4);
	      *p++ = tohex (i & 15);
	      if (count)
		*p++ = ';';
	      else
		break;
	      count--;
	    }
	}
      *p = 0;
      if (!rs->last_program_signals_packet
	  || strcmp (rs->last_program_signals_packet, packet) != 0)
	{
	  putpkt (packet);
	  getpkt (&rs->buf, &rs->buf_size, 0);
	  packet_ok (rs->buf, &remote_protocol_packets[PACKET_QProgramSignals]);
	  xfree (rs->last_program_signals_packet);
	  rs->last_program_signals_packet = packet;
	}
      else
	xfree (packet);
    }
}

/* If PTID is MAGIC_NULL_PTID, don't set any thread.  If PTID is
   MINUS_ONE_PTID, set the thread to -1, so the stub returns the
   thread.  If GEN is set, set the general thread, if not, then set
   the step/continue thread.  */
static void
set_thread (struct ptid ptid, int gen)
{
  struct remote_state *rs = get_remote_state ();
  ptid_t state = gen ? rs->general_thread : rs->continue_thread;
  char *buf = rs->buf;
  char *endbuf = rs->buf + get_remote_packet_size ();

  if (ptid_equal (state, ptid))
    return;

  *buf++ = 'H';
  *buf++ = gen ? 'g' : 'c';
  if (ptid_equal (ptid, magic_null_ptid))
    xsnprintf (buf, endbuf - buf, "0");
  else if (ptid_equal (ptid, any_thread_ptid))
    xsnprintf (buf, endbuf - buf, "0");
  else if (ptid_equal (ptid, minus_one_ptid))
    xsnprintf (buf, endbuf - buf, "-1");
  else
    write_ptid (buf, endbuf, ptid);
  putpkt (rs->buf);
  getpkt (&rs->buf, &rs->buf_size, 0);
  if (gen)
    rs->general_thread = ptid;
  else
    rs->continue_thread = ptid;
}

static void
set_general_thread (struct ptid ptid)
{
  set_thread (ptid, 1);
}

static void
set_continue_thread (struct ptid ptid)
{
  set_thread (ptid, 0);
}

/* Change the remote current process.  Which thread within the process
   ends up selected isn't important, as long as it is the same process
   as what INFERIOR_PTID points to.

   This comes from that fact that there is no explicit notion of
   "selected process" in the protocol.  The selected process for
   general operations is the process the selected general thread
   belongs to.  */

static void
set_general_process (void)
{
  struct remote_state *rs = get_remote_state ();

  /* If the remote can't handle multiple processes, don't bother.  */
  if (!remote_multi_process_p (rs))
    return;

  /* We only need to change the remote current thread if it's pointing
     at some other process.  */
  if (ptid_get_pid (rs->general_thread) != ptid_get_pid (inferior_ptid))
    set_general_thread (inferior_ptid);
}


/* Return nonzero if this is the main thread that we made up ourselves
   to model non-threaded targets as single-threaded.  */

static int
remote_thread_always_alive (struct target_ops *ops, ptid_t ptid)
{
  if (ptid_equal (ptid, magic_null_ptid))
    /* The main thread is always alive.  */
    return 1;

  if (ptid_get_pid (ptid) != 0 && ptid_get_lwp (ptid) == 0)
    /* The main thread is always alive.  This can happen after a
       vAttach, if the remote side doesn't support
       multi-threading.  */
    return 1;

  return 0;
}

/* Return nonzero if the thread PTID is still alive on the remote
   system.  */

static int
remote_thread_alive (struct target_ops *ops, ptid_t ptid)
{
  struct remote_state *rs = get_remote_state ();
  char *p, *endp;

  /* Check if this is a thread that we made up ourselves to model
     non-threaded targets as single-threaded.  */
  if (remote_thread_always_alive (ops, ptid))
    return 1;

  p = rs->buf;
  endp = rs->buf + get_remote_packet_size ();

  *p++ = 'T';
  write_ptid (p, endp, ptid);

  putpkt (rs->buf);
  getpkt (&rs->buf, &rs->buf_size, 0);
  return (rs->buf[0] == 'O' && rs->buf[1] == 'K');
}

/* Return a pointer to a thread name if we know it and NULL otherwise.
   The thread_info object owns the memory for the name.  */

static const char *
remote_thread_name (struct target_ops *ops, struct thread_info *info)
{
  if (info->priv != NULL)
    return info->priv->name;

  return NULL;
}

/* About these extended threadlist and threadinfo packets.  They are
   variable length packets but, the fields within them are often fixed
   length.  They are redundent enough to send over UDP as is the
   remote protocol in general.  There is a matching unit test module
   in libstub.  */

/* WARNING: This threadref data structure comes from the remote O.S.,
   libstub protocol encoding, and remote.c.  It is not particularly
   changable.  */

/* Right now, the internal structure is int. We want it to be bigger.
   Plan to fix this.  */

typedef int gdb_threadref;	/* Internal GDB thread reference.  */

/* gdb_ext_thread_info is an internal GDB data structure which is
   equivalent to the reply of the remote threadinfo packet.  */

struct gdb_ext_thread_info
  {
    threadref threadid;		/* External form of thread reference.  */
    int active;			/* Has state interesting to GDB?
				   regs, stack.  */
    char display[256];		/* Brief state display, name,
				   blocked/suspended.  */
    char shortname[32];		/* To be used to name threads.  */
    char more_display[256];	/* Long info, statistics, queue depth,
				   whatever.  */
  };

/* The volume of remote transfers can be limited by submitting
   a mask containing bits specifying the desired information.
   Use a union of these values as the 'selection' parameter to
   get_thread_info.  FIXME: Make these TAG names more thread specific.  */

#define TAG_THREADID 1
#define TAG_EXISTS 2
#define TAG_DISPLAY 4
#define TAG_THREADNAME 8
#define TAG_MOREDISPLAY 16

#define BUF_THREAD_ID_SIZE (OPAQUETHREADBYTES * 2)

static char *unpack_nibble (char *buf, int *val);

static char *unpack_byte (char *buf, int *value);

static char *pack_int (char *buf, int value);

static char *unpack_int (char *buf, int *value);

static char *unpack_string (char *src, char *dest, int length);

static char *pack_threadid (char *pkt, threadref *id);

static char *unpack_threadid (char *inbuf, threadref *id);

void int_to_threadref (threadref *id, int value);

static int threadref_to_int (threadref *ref);

static void copy_threadref (threadref *dest, threadref *src);

static int threadmatch (threadref *dest, threadref *src);

static char *pack_threadinfo_request (char *pkt, int mode,
				      threadref *id);

static int remote_unpack_thread_info_response (char *pkt,
					       threadref *expectedref,
					       struct gdb_ext_thread_info
					       *info);


static int remote_get_threadinfo (threadref *threadid,
				  int fieldset,	/*TAG mask */
				  struct gdb_ext_thread_info *info);

static char *pack_threadlist_request (char *pkt, int startflag,
				      int threadcount,
				      threadref *nextthread);

static int parse_threadlist_response (char *pkt,
				      int result_limit,
				      threadref *original_echo,
				      threadref *resultlist,
				      int *doneflag);

static int remote_get_threadlist (int startflag,
				  threadref *nextthread,
				  int result_limit,
				  int *done,
				  int *result_count,
				  threadref *threadlist);

typedef int (*rmt_thread_action) (threadref *ref, void *context);

static int remote_threadlist_iterator (rmt_thread_action stepfunction,
				       void *context, int looplimit);

static int remote_newthread_step (threadref *ref, void *context);


/* Write a PTID to BUF.  ENDBUF points to one-passed-the-end of the
   buffer we're allowed to write to.  Returns
   BUF+CHARACTERS_WRITTEN.  */

static char *
write_ptid (char *buf, const char *endbuf, ptid_t ptid)
{
  int pid, tid;
  struct remote_state *rs = get_remote_state ();

  if (remote_multi_process_p (rs))
    {
      pid = ptid_get_pid (ptid);
      if (pid < 0)
	buf += xsnprintf (buf, endbuf - buf, "p-%x.", -pid);
      else
	buf += xsnprintf (buf, endbuf - buf, "p%x.", pid);
    }
  tid = ptid_get_lwp (ptid);
  if (tid < 0)
    buf += xsnprintf (buf, endbuf - buf, "-%x", -tid);
  else
    buf += xsnprintf (buf, endbuf - buf, "%x", tid);

  return buf;
}

/* Extract a PTID from BUF.  If non-null, OBUF is set to the to one
   passed the last parsed char.  Returns null_ptid on error.  */

static ptid_t
read_ptid (char *buf, char **obuf)
{
  char *p = buf;
  char *pp;
  ULONGEST pid = 0, tid = 0;

  if (*p == 'p')
    {
      /* Multi-process ptid.  */
      pp = unpack_varlen_hex (p + 1, &pid);
      if (*pp != '.')
	error (_("invalid remote ptid: %s"), p);

      p = pp;
      pp = unpack_varlen_hex (p + 1, &tid);
      if (obuf)
	*obuf = pp;
      return ptid_build (pid, tid, 0);
    }

  /* No multi-process.  Just a tid.  */
  pp = unpack_varlen_hex (p, &tid);

  /* Return null_ptid when no thread id is found.  */
  if (p == pp)
    {
      if (obuf)
	*obuf = pp;
      return null_ptid;
    }

  /* Since the stub is not sending a process id, then default to
     what's in inferior_ptid, unless it's null at this point.  If so,
     then since there's no way to know the pid of the reported
     threads, use the magic number.  */
  if (ptid_equal (inferior_ptid, null_ptid))
    pid = ptid_get_pid (magic_null_ptid);
  else
    pid = ptid_get_pid (inferior_ptid);

  if (obuf)
    *obuf = pp;
  return ptid_build (pid, tid, 0);
}

static int
stubhex (int ch)
{
  if (ch >= 'a' && ch <= 'f')
    return ch - 'a' + 10;
  if (ch >= '0' && ch <= '9')
    return ch - '0';
  if (ch >= 'A' && ch <= 'F')
    return ch - 'A' + 10;
  return -1;
}

static int
stub_unpack_int (char *buff, int fieldlength)
{
  int nibble;
  int retval = 0;

  while (fieldlength)
    {
      nibble = stubhex (*buff++);
      retval |= nibble;
      fieldlength--;
      if (fieldlength)
	retval = retval << 4;
    }
  return retval;
}

static char *
unpack_nibble (char *buf, int *val)
{
  *val = fromhex (*buf++);
  return buf;
}

static char *
unpack_byte (char *buf, int *value)
{
  *value = stub_unpack_int (buf, 2);
  return buf + 2;
}

static char *
pack_int (char *buf, int value)
{
  buf = pack_hex_byte (buf, (value >> 24) & 0xff);
  buf = pack_hex_byte (buf, (value >> 16) & 0xff);
  buf = pack_hex_byte (buf, (value >> 8) & 0x0ff);
  buf = pack_hex_byte (buf, (value & 0xff));
  return buf;
}

static char *
unpack_int (char *buf, int *value)
{
  *value = stub_unpack_int (buf, 8);
  return buf + 8;
}

#if 0			/* Currently unused, uncomment when needed.  */
static char *pack_string (char *pkt, char *string);

static char *
pack_string (char *pkt, char *string)
{
  char ch;
  int len;

  len = strlen (string);
  if (len > 200)
    len = 200;		/* Bigger than most GDB packets, junk???  */
  pkt = pack_hex_byte (pkt, len);
  while (len-- > 0)
    {
      ch = *string++;
      if ((ch == '\0') || (ch == '#'))
	ch = '*';		/* Protect encapsulation.  */
      *pkt++ = ch;
    }
  return pkt;
}
#endif /* 0 (unused) */

static char *
unpack_string (char *src, char *dest, int length)
{
  while (length--)
    *dest++ = *src++;
  *dest = '\0';
  return src;
}

static char *
pack_threadid (char *pkt, threadref *id)
{
  char *limit;
  unsigned char *altid;

  altid = (unsigned char *) id;
  limit = pkt + BUF_THREAD_ID_SIZE;
  while (pkt < limit)
    pkt = pack_hex_byte (pkt, *altid++);
  return pkt;
}


static char *
unpack_threadid (char *inbuf, threadref *id)
{
  char *altref;
  char *limit = inbuf + BUF_THREAD_ID_SIZE;
  int x, y;

  altref = (char *) id;

  while (inbuf < limit)
    {
      x = stubhex (*inbuf++);
      y = stubhex (*inbuf++);
      *altref++ = (x << 4) | y;
    }
  return inbuf;
}

/* Externally, threadrefs are 64 bits but internally, they are still
   ints.  This is due to a mismatch of specifications.  We would like
   to use 64bit thread references internally.  This is an adapter
   function.  */

void
int_to_threadref (threadref *id, int value)
{
  unsigned char *scan;

  scan = (unsigned char *) id;
  {
    int i = 4;
    while (i--)
      *scan++ = 0;
  }
  *scan++ = (value >> 24) & 0xff;
  *scan++ = (value >> 16) & 0xff;
  *scan++ = (value >> 8) & 0xff;
  *scan++ = (value & 0xff);
}

static int
threadref_to_int (threadref *ref)
{
  int i, value = 0;
  unsigned char *scan;

  scan = *ref;
  scan += 4;
  i = 4;
  while (i-- > 0)
    value = (value << 8) | ((*scan++) & 0xff);
  return value;
}

static void
copy_threadref (threadref *dest, threadref *src)
{
  int i;
  unsigned char *csrc, *cdest;

  csrc = (unsigned char *) src;
  cdest = (unsigned char *) dest;
  i = 8;
  while (i--)
    *cdest++ = *csrc++;
}

static int
threadmatch (threadref *dest, threadref *src)
{
  /* Things are broken right now, so just assume we got a match.  */
#if 0
  unsigned char *srcp, *destp;
  int i, result;
  srcp = (char *) src;
  destp = (char *) dest;

  result = 1;
  while (i-- > 0)
    result &= (*srcp++ == *destp++) ? 1 : 0;
  return result;
#endif
  return 1;
}

/*
   threadid:1,        # always request threadid
   context_exists:2,
   display:4,
   unique_name:8,
   more_display:16
 */

/* Encoding:  'Q':8,'P':8,mask:32,threadid:64 */

static char *
pack_threadinfo_request (char *pkt, int mode, threadref *id)
{
  *pkt++ = 'q';				/* Info Query */
  *pkt++ = 'P';				/* process or thread info */
  pkt = pack_int (pkt, mode);		/* mode */
  pkt = pack_threadid (pkt, id);	/* threadid */
  *pkt = '\0';				/* terminate */
  return pkt;
}

/* These values tag the fields in a thread info response packet.  */
/* Tagging the fields allows us to request specific fields and to
   add more fields as time goes by.  */

#define TAG_THREADID 1		/* Echo the thread identifier.  */
#define TAG_EXISTS 2		/* Is this process defined enough to
				   fetch registers and its stack?  */
#define TAG_DISPLAY 4		/* A short thing maybe to put on a window */
#define TAG_THREADNAME 8	/* string, maps 1-to-1 with a thread is.  */
#define TAG_MOREDISPLAY 16	/* Whatever the kernel wants to say about
				   the process.  */

static int
remote_unpack_thread_info_response (char *pkt, threadref *expectedref,
				    struct gdb_ext_thread_info *info)
{
  struct remote_state *rs = get_remote_state ();
  int mask, length;
  int tag;
  threadref ref;
  char *limit = pkt + rs->buf_size; /* Plausible parsing limit.  */
  int retval = 1;

  /* info->threadid = 0; FIXME: implement zero_threadref.  */
  info->active = 0;
  info->display[0] = '\0';
  info->shortname[0] = '\0';
  info->more_display[0] = '\0';

  /* Assume the characters indicating the packet type have been
     stripped.  */
  pkt = unpack_int (pkt, &mask);	/* arg mask */
  pkt = unpack_threadid (pkt, &ref);

  if (mask == 0)
    warning (_("Incomplete response to threadinfo request."));
  if (!threadmatch (&ref, expectedref))
    {			/* This is an answer to a different request.  */
      warning (_("ERROR RMT Thread info mismatch."));
      return 0;
    }
  copy_threadref (&info->threadid, &ref);

  /* Loop on tagged fields , try to bail if somthing goes wrong.  */

  /* Packets are terminated with nulls.  */
  while ((pkt < limit) && mask && *pkt)
    {
      pkt = unpack_int (pkt, &tag);	/* tag */
      pkt = unpack_byte (pkt, &length);	/* length */
      if (!(tag & mask))		/* Tags out of synch with mask.  */
	{
	  warning (_("ERROR RMT: threadinfo tag mismatch."));
	  retval = 0;
	  break;
	}
      if (tag == TAG_THREADID)
	{
	  if (length != 16)
	    {
	      warning (_("ERROR RMT: length of threadid is not 16."));
	      retval = 0;
	      break;
	    }
	  pkt = unpack_threadid (pkt, &ref);
	  mask = mask & ~TAG_THREADID;
	  continue;
	}
      if (tag == TAG_EXISTS)
	{
	  info->active = stub_unpack_int (pkt, length);
	  pkt += length;
	  mask = mask & ~(TAG_EXISTS);
	  if (length > 8)
	    {
	      warning (_("ERROR RMT: 'exists' length too long."));
	      retval = 0;
	      break;
	    }
	  continue;
	}
      if (tag == TAG_THREADNAME)
	{
	  pkt = unpack_string (pkt, &info->shortname[0], length);
	  mask = mask & ~TAG_THREADNAME;
	  continue;
	}
      if (tag == TAG_DISPLAY)
	{
	  pkt = unpack_string (pkt, &info->display[0], length);
	  mask = mask & ~TAG_DISPLAY;
	  continue;
	}
      if (tag == TAG_MOREDISPLAY)
	{
	  pkt = unpack_string (pkt, &info->more_display[0], length);
	  mask = mask & ~TAG_MOREDISPLAY;
	  continue;
	}
      warning (_("ERROR RMT: unknown thread info tag."));
      break;			/* Not a tag we know about.  */
    }
  return retval;
}

static int
remote_get_threadinfo (threadref *threadid, int fieldset,	/* TAG mask */
		       struct gdb_ext_thread_info *info)
{
  struct remote_state *rs = get_remote_state ();
  int result;

  pack_threadinfo_request (rs->buf, fieldset, threadid);
  putpkt (rs->buf);
  getpkt (&rs->buf, &rs->buf_size, 0);

  if (rs->buf[0] == '\0')
    return 0;

  result = remote_unpack_thread_info_response (rs->buf + 2,
					       threadid, info);
  return result;
}

/*    Format: i'Q':8,i"L":8,initflag:8,batchsize:16,lastthreadid:32   */

static char *
pack_threadlist_request (char *pkt, int startflag, int threadcount,
			 threadref *nextthread)
{
  *pkt++ = 'q';			/* info query packet */
  *pkt++ = 'L';			/* Process LIST or threadLIST request */
  pkt = pack_nibble (pkt, startflag);		/* initflag 1 bytes */
  pkt = pack_hex_byte (pkt, threadcount);	/* threadcount 2 bytes */
  pkt = pack_threadid (pkt, nextthread);	/* 64 bit thread identifier */
  *pkt = '\0';
  return pkt;
}

/* Encoding:   'q':8,'M':8,count:16,done:8,argthreadid:64,(threadid:64)* */

static int
parse_threadlist_response (char *pkt, int result_limit,
			   threadref *original_echo, threadref *resultlist,
			   int *doneflag)
{
  struct remote_state *rs = get_remote_state ();
  char *limit;
  int count, resultcount, done;

  resultcount = 0;
  /* Assume the 'q' and 'M chars have been stripped.  */
  limit = pkt + (rs->buf_size - BUF_THREAD_ID_SIZE);
  /* done parse past here */
  pkt = unpack_byte (pkt, &count);	/* count field */
  pkt = unpack_nibble (pkt, &done);
  /* The first threadid is the argument threadid.  */
  pkt = unpack_threadid (pkt, original_echo);	/* should match query packet */
  while ((count-- > 0) && (pkt < limit))
    {
      pkt = unpack_threadid (pkt, resultlist++);
      if (resultcount++ >= result_limit)
	break;
    }
  if (doneflag)
    *doneflag = done;
  return resultcount;
}

/* Fetch the next batch of threads from the remote.  Returns -1 if the
   qL packet is not supported, 0 on error and 1 on success.  */

static int
remote_get_threadlist (int startflag, threadref *nextthread, int result_limit,
		       int *done, int *result_count, threadref *threadlist)
{
  struct remote_state *rs = get_remote_state ();
  int result = 1;

  /* Trancate result limit to be smaller than the packet size.  */
  if ((((result_limit + 1) * BUF_THREAD_ID_SIZE) + 10)
      >= get_remote_packet_size ())
    result_limit = (get_remote_packet_size () / BUF_THREAD_ID_SIZE) - 2;

  pack_threadlist_request (rs->buf, startflag, result_limit, nextthread);
  putpkt (rs->buf);
  getpkt (&rs->buf, &rs->buf_size, 0);
  if (*rs->buf == '\0')
    {
      /* Packet not supported.  */
      return -1;
    }

  *result_count =
    parse_threadlist_response (rs->buf + 2, result_limit,
			       &rs->echo_nextthread, threadlist, done);

  if (!threadmatch (&rs->echo_nextthread, nextthread))
    {
      /* FIXME: This is a good reason to drop the packet.  */
      /* Possably, there is a duplicate response.  */
      /* Possabilities :
         retransmit immediatly - race conditions
         retransmit after timeout - yes
         exit
         wait for packet, then exit
       */
      warning (_("HMM: threadlist did not echo arg thread, dropping it."));
      return 0;			/* I choose simply exiting.  */
    }
  if (*result_count <= 0)
    {
      if (*done != 1)
	{
	  warning (_("RMT ERROR : failed to get remote thread list."));
	  result = 0;
	}
      return result;		/* break; */
    }
  if (*result_count > result_limit)
    {
      *result_count = 0;
      warning (_("RMT ERROR: threadlist response longer than requested."));
      return 0;
    }
  return result;
}

/* Fetch the list of remote threads, with the qL packet, and call
   STEPFUNCTION for each thread found.  Stops iterating and returns 1
   if STEPFUNCTION returns true.  Stops iterating and returns 0 if the
   STEPFUNCTION returns false.  If the packet is not supported,
   returns -1.  */

static int
remote_threadlist_iterator (rmt_thread_action stepfunction, void *context,
			    int looplimit)
{
  struct remote_state *rs = get_remote_state ();
  int done, i, result_count;
  int startflag = 1;
  int result = 1;
  int loopcount = 0;

  done = 0;
  while (!done)
    {
      if (loopcount++ > looplimit)
	{
	  result = 0;
	  warning (_("Remote fetch threadlist -infinite loop-."));
	  break;
	}
      result = remote_get_threadlist (startflag, &rs->nextthread,
				      MAXTHREADLISTRESULTS,
				      &done, &result_count,
				      rs->resultthreadlist);
      if (result <= 0)
	break;
      /* Clear for later iterations.  */
      startflag = 0;
      /* Setup to resume next batch of thread references, set nextthread.  */
      if (result_count >= 1)
	copy_threadref (&rs->nextthread,
			&rs->resultthreadlist[result_count - 1]);
      i = 0;
      while (result_count--)
	{
	  if (!(*stepfunction) (&rs->resultthreadlist[i++], context))
	    {
	      result = 0;
	      break;
	    }
	}
    }
  return result;
}

/* A thread found on the remote target.  */

typedef struct thread_item
{
  /* The thread's PTID.  */
  ptid_t ptid;

  /* The thread's extra info.  May be NULL.  */
  char *extra;

  /* The thread's name.  May be NULL.  */
  char *name;

  /* The core the thread was running on.  -1 if not known.  */
  int core;
} thread_item_t;
DEF_VEC_O(thread_item_t);

/* Context passed around to the various methods listing remote
   threads.  As new threads are found, they're added to the ITEMS
   vector.  */

struct threads_listing_context
{
  /* The threads found on the remote target.  */
  VEC (thread_item_t) *items;
};