gdbserver/server.cc

/* Main code for remote server for GDB.
   Copyright (C) 1989-2021 Free Software Foundation, Inc.

   This file is part of GDB.

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

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

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

#include "server.h"
#include "gdbthread.h"
#include "gdbsupport/agent.h"
#include "notif.h"
#include "tdesc.h"
#include "gdbsupport/rsp-low.h"
#include "gdbsupport/signals-state-save-restore.h"
#include <ctype.h>
#include <unistd.h>
#if HAVE_SIGNAL_H
#include <signal.h>
#endif
#include "gdbsupport/gdb_vecs.h"
#include "gdbsupport/gdb_wait.h"
#include "gdbsupport/btrace-common.h"
#include "gdbsupport/filestuff.h"
#include "tracepoint.h"
#include "dll.h"
#include "hostio.h"
#include <vector>
#include "gdbsupport/common-inferior.h"
#include "gdbsupport/job-control.h"
#include "gdbsupport/environ.h"
#include "filenames.h"
#include "gdbsupport/pathstuff.h"
#ifdef USE_XML
#include "xml-builtin.h"
#endif

#include "gdbsupport/selftest.h"
#include "gdbsupport/scope-exit.h"
#include "gdbsupport/gdb_select.h"
#include "gdbsupport/scoped_restore.h"
#include "gdbsupport/search.h"

#define require_running_or_return(BUF)		\
  if (!target_running ())			\
    {						\
      write_enn (BUF);				\
      return;					\
    }

#define require_running_or_break(BUF)		\
  if (!target_running ())			\
    {						\
      write_enn (BUF);				\
      break;					\
    }

/* String containing the current directory (what getwd would return).  */

char *current_directory;

/* The environment to pass to the inferior when creating it.  */

static gdb_environ our_environ;

bool server_waiting;

static bool extended_protocol;
static bool response_needed;
static bool exit_requested;

/* --once: Exit after the first connection has closed.  */
bool run_once;

/* Whether to report TARGET_WAITKIND_NO_RESUMED events.  */
static bool report_no_resumed;

/* The event loop checks this to decide whether to continue accepting
   events.  */
static bool keep_processing_events = true;

bool non_stop;

static struct {
  /* Set the PROGRAM_PATH.  Here we adjust the path of the provided
     binary if needed.  */
  void set (gdb::unique_xmalloc_ptr<char> &&path)
  {
    m_path = std::move (path);

    /* Make sure we're using the absolute path of the inferior when
       creating it.  */
    if (!contains_dir_separator (m_path.get ()))
      {
	int reg_file_errno;

	/* Check if the file is in our CWD.  If it is, then we prefix
	   its name with CURRENT_DIRECTORY.  Otherwise, we leave the
	   name as-is because we'll try searching for it in $PATH.  */
	if (is_regular_file (m_path.get (), &reg_file_errno))
	  m_path = gdb_abspath (m_path.get ());
      }
  }

  /* Return the PROGRAM_PATH.  */
  char *get ()
  { return m_path.get (); }

private:
  /* The program name, adjusted if needed.  */
  gdb::unique_xmalloc_ptr<char> m_path;
} program_path;
static std::vector<char *> program_args;
static std::string wrapper_argv;

/* The PID of the originally created or attached inferior.  Used to
   send signals to the process when GDB sends us an asynchronous interrupt
   (user hitting Control-C in the client), and to wait for the child to exit
   when no longer debugging it.  */

unsigned long signal_pid;

/* Set if you want to disable optional thread related packets support
   in gdbserver, for the sake of testing GDB against stubs that don't
   support them.  */
bool disable_packet_vCont;
bool disable_packet_Tthread;
bool disable_packet_qC;
bool disable_packet_qfThreadInfo;
bool disable_packet_T;

static unsigned char *mem_buf;

/* A sub-class of 'struct notif_event' for stop, holding information
   relative to a single stop reply.  We keep a queue of these to
   push to GDB in non-stop mode.  */

struct vstop_notif : public notif_event
{
  /* Thread or process that got the event.  */
  ptid_t ptid;

  /* Event info.  */
  struct target_waitstatus status;
};

/* The current btrace configuration.  This is gdbserver's mirror of GDB's
   btrace configuration.  */
static struct btrace_config current_btrace_conf;

/* The client remote protocol state. */

static client_state g_client_state;

client_state &
get_client_state ()
{
  client_state &cs = g_client_state;
  return cs;
}


/* Put a stop reply to the stop reply queue.  */

static void
queue_stop_reply (ptid_t ptid, struct target_waitstatus *status)
{
  struct vstop_notif *new_notif = new struct vstop_notif;

  new_notif->ptid = ptid;
  new_notif->status = *status;

  notif_event_enque (&notif_stop, new_notif);
}

static bool
remove_all_on_match_ptid (struct notif_event *event, ptid_t filter_ptid)
{
  struct vstop_notif *vstop_event = (struct vstop_notif *) event;

  return vstop_event->ptid.matches (filter_ptid);
}

/* See server.h.  */

void
discard_queued_stop_replies (ptid_t ptid)
{
  std::list<notif_event *>::iterator iter, next, end;
  end = notif_stop.queue.end ();
  for (iter = notif_stop.queue.begin (); iter != end; iter = next)
    {
      next = iter;
      ++next;

      if (iter == notif_stop.queue.begin ())
	{
	  /* The head of the list contains the notification that was
	     already sent to GDB.  So we can't remove it, otherwise
	     when GDB sends the vStopped, it would ack the _next_
	     notification, which hadn't been sent yet!  */
	  continue;
	}

      if (remove_all_on_match_ptid (*iter, ptid))
	{
	  delete *iter;
	  notif_stop.queue.erase (iter);
	}
    }
}

static void
vstop_notif_reply (struct notif_event *event, char *own_buf)
{
  struct vstop_notif *vstop = (struct vstop_notif *) event;

  prepare_resume_reply (own_buf, vstop->ptid, &vstop->status);
}

/* Helper for in_queued_stop_replies.  */

static bool
in_queued_stop_replies_ptid (struct notif_event *event, ptid_t filter_ptid)
{
  struct vstop_notif *vstop_event = (struct vstop_notif *) event;

  if (vstop_event->ptid.matches (filter_ptid))
    return true;

  /* Don't resume fork children that GDB does not know about yet.  */
  if ((vstop_event->status.kind == TARGET_WAITKIND_FORKED
       || vstop_event->status.kind == TARGET_WAITKIND_VFORKED)
      && vstop_event->status.value.related_pid.matches (filter_ptid))
    return true;

  return false;
}

/* See server.h.  */

int
in_queued_stop_replies (ptid_t ptid)
{
  for (notif_event *event : notif_stop.queue)
    {
      if (in_queued_stop_replies_ptid (event, ptid))
	return true;
    }

  return false;
}

struct notif_server notif_stop =
{
  "vStopped", "Stop", {}, vstop_notif_reply,
};

static int
target_running (void)
{
  return get_first_thread () != NULL;
}

/* See gdbsupport/common-inferior.h.  */

const char *
get_exec_wrapper ()
{
  return !wrapper_argv.empty () ? wrapper_argv.c_str () : NULL;
}

/* See gdbsupport/common-inferior.h.  */

const char *
get_exec_file (int err)
{
  if (err && program_path.get () == NULL)
    error (_("No executable file specified."));

  return program_path.get ();
}

/* See server.h.  */

gdb_environ *
get_environ ()
{
  return &our_environ;
}

static int
attach_inferior (int pid)
{
  client_state &cs = get_client_state ();
  /* myattach should return -1 if attaching is unsupported,
     0 if it succeeded, and call error() otherwise.  */

  if (find_process_pid (pid) != nullptr)
    error ("Already attached to process %d\n", pid);

  if (myattach (pid) != 0)
    return -1;

  fprintf (stderr, "Attached; pid = %d\n", pid);
  fflush (stderr);

  /* FIXME - It may be that we should get the SIGNAL_PID from the
     attach function, so that it can be the main thread instead of
     whichever we were told to attach to.  */
  signal_pid = pid;

  if (!non_stop)
    {
      cs.last_ptid = mywait (ptid_t (pid), &cs.last_status, 0, 0);

      /* GDB knows to ignore the first SIGSTOP after attaching to a running
	 process using the "attach" command, but this is different; it's
	 just using "target remote".  Pretend it's just starting up.  */
      if (cs.last_status.kind == TARGET_WAITKIND_STOPPED
	  && cs.last_status.value.sig == GDB_SIGNAL_STOP)
	cs.last_status.value.sig = GDB_SIGNAL_TRAP;

      current_thread->last_resume_kind = resume_stop;
      current_thread->last_status = cs.last_status;
    }

  return 0;
}

/* Decode a qXfer read request.  Return 0 if everything looks OK,
   or -1 otherwise.  */

static int
decode_xfer_read (char *buf, CORE_ADDR *ofs, unsigned int *len)
{
  /* After the read marker and annex, qXfer looks like a
     traditional 'm' packet.  */
  decode_m_packet (buf, ofs, len);

  return 0;
}

static int
decode_xfer (char *buf, char **object, char **rw, char **annex, char **offset)
{
  /* Extract and NUL-terminate the object.  */
  *object = buf;
  while (*buf && *buf != ':')
    buf++;
  if (*buf == '\0')
    return -1;
  *buf++ = 0;

  /* Extract and NUL-terminate the read/write action.  */
  *rw = buf;
  while (*buf && *buf != ':')
    buf++;
  if (*buf == '\0')
    return -1;
  *buf++ = 0;

  /* Extract and NUL-terminate the annex.  */
  *annex = buf;
  while (*buf && *buf != ':')
    buf++;
  if (*buf == '\0')
    return -1;
  *buf++ = 0;

  *offset = buf;
  return 0;
}

/* Write the response to a successful qXfer read.  Returns the
   length of the (binary) data stored in BUF, corresponding
   to as much of DATA/LEN as we could fit.  IS_MORE controls
   the first character of the response.  */
static int
write_qxfer_response (char *buf, const gdb_byte *data, int len, int is_more)
{
  int out_len;

  if (is_more)
    buf[0] = 'm';
  else
    buf[0] = 'l';

  return remote_escape_output (data, len, 1, (unsigned char *) buf + 1,
			       &out_len, PBUFSIZ - 2) + 1;
}

/* Handle btrace enabling in BTS format.  */

static void
handle_btrace_enable_bts (struct thread_info *thread)
{
  if (thread->btrace != NULL)
    error (_("Btrace already enabled."));

  current_btrace_conf.format = BTRACE_FORMAT_BTS;
  thread->btrace = target_enable_btrace (thread->id, &current_btrace_conf);
}

/* Handle btrace enabling in Intel Processor Trace format.  */

static void
handle_btrace_enable_pt (struct thread_info *thread)
{
  if (thread->btrace != NULL)
    error (_("Btrace already enabled."));

  current_btrace_conf.format = BTRACE_FORMAT_PT;
  thread->btrace = target_enable_btrace (thread->id, &current_btrace_conf);
}

/* Handle btrace disabling.  */

static void
handle_btrace_disable (struct thread_info *thread)
{

  if (thread->btrace == NULL)
    error (_("Branch tracing not enabled."));

  if (target_disable_btrace (thread->btrace) != 0)
    error (_("Could not disable branch tracing."));

  thread->btrace = NULL;
}

/* Handle the "Qbtrace" packet.  */

static int
handle_btrace_general_set (char *own_buf)
{
  client_state &cs = get_client_state ();
  struct thread_info *thread;
  char *op;

  if (!startswith (own_buf, "Qbtrace:"))
    return 0;

  op = own_buf + strlen ("Qbtrace:");

  if (cs.general_thread == null_ptid
      || cs.general_thread == minus_one_ptid)
    {
      strcpy (own_buf, "E.Must select a single thread.");
      return -1;
    }

  thread = find_thread_ptid (cs.general_thread);
  if (thread == NULL)
    {
      strcpy (own_buf, "E.No such thread.");
      return -1;
    }

  try
    {
      if (strcmp (op, "bts") == 0)
	handle_btrace_enable_bts (thread);
      else if (strcmp (op, "pt") == 0)
	handle_btrace_enable_pt (thread);
      else if (strcmp (op, "off") == 0)
	handle_btrace_disable (thread);
      else
	error (_("Bad Qbtrace operation.  Use bts, pt, or off."));

      write_ok (own_buf);
    }
  catch (const gdb_exception_error &exception)
    {
      sprintf (own_buf, "E.%s", exception.what ());
    }

  return 1;
}

/* Handle the "Qbtrace-conf" packet.  */

static int
handle_btrace_conf_general_set (char *own_buf)
{
  client_state &cs = get_client_state ();
  struct thread_info *thread;
  char *op;

  if (!startswith (own_buf, "Qbtrace-conf:"))
    return 0;

  op = own_buf + strlen ("Qbtrace-conf:");

  if (cs.general_thread == null_ptid
      || cs.general_thread == minus_one_ptid)
    {
      strcpy (own_buf, "E.Must select a single thread.");
      return -1;
    }

  thread = find_thread_ptid (cs.general_thread);
  if (thread == NULL)
    {
      strcpy (own_buf, "E.No such thread.");
      return -1;
    }

  if (startswith (op, "bts:size="))
    {
      unsigned long size;
      char *endp = NULL;

      errno = 0;
      size = strtoul (op + strlen ("bts:size="), &endp, 16);
      if (endp == NULL || *endp != 0 || errno != 0 || size > UINT_MAX)
	{
	  strcpy (own_buf, "E.Bad size value.");
	  return -1;
	}

      current_btrace_conf.bts.size = (unsigned int) size;
    }
  else if (strncmp (op, "pt:size=", strlen ("pt:size=")) == 0)
    {
      unsigned long size;
      char *endp = NULL;

      errno = 0;
      size = strtoul (op + strlen ("pt:size="), &endp, 16);
      if (endp == NULL || *endp != 0 || errno != 0 || size > UINT_MAX)
	{
	  strcpy (own_buf, "E.Bad size value.");
	  return -1;
	}

      current_btrace_conf.pt.size = (unsigned int) size;
    }
  else
    {
      strcpy (own_buf, "E.Bad Qbtrace configuration option.");
      return -1;
    }

  write_ok (own_buf);
  return 1;
}

/* Create the qMemTags packet reply given TAGS.

   Returns true if parsing succeeded and false otherwise.  */

static bool
create_fetch_memtags_reply (char *reply, const gdb::byte_vector &tags)
{
  /* It is an error to pass a zero-sized tag vector.  */
  gdb_assert (tags.size () != 0);

  std::string packet ("m");

  /* Write the tag data.  */
  packet += bin2hex (tags.data (), tags.size ());

  /* Check if the reply is too big for the packet to handle.  */
  if (PBUFSIZ < packet.size ())
    return false;

  strcpy (reply, packet.c_str ());
  return true;
}

/* Parse the QMemTags request into ADDR, LEN and TAGS.

   Returns true if parsing succeeded and false otherwise.  */

static bool
parse_store_memtags_request (char *request, CORE_ADDR *addr, size_t *len,
			     gdb::byte_vector &tags, int *type)
{
  gdb_assert (startswith (request, "QMemTags:"));

  const char *p = request + strlen ("QMemTags:");

  /* Read address and length.  */
  unsigned int length = 0;
  p = decode_m_packet_params (p, addr, &length, ':');
  *len = length;

  /* Read the tag type.  */
  ULONGEST tag_type = 0;
  p = unpack_varlen_hex (p, &tag_type);
  *type = (int) tag_type;

  /* Make sure there is a colon after the type.  */
  if (*p != ':')
    return false;

  /* Skip the colon.  */
  p++;

  /* Read the tag data.  */
  tags = hex2bin (p);

  return true;
}

/* Handle all of the extended 'Q' packets.  */

static void
handle_general_set (char *own_buf)
{
  client_state &cs = get_client_state ();
  if (startswith (own_buf, "QPassSignals:"))
    {
      int numsigs = (int) GDB_SIGNAL_LAST, i;
      const char *p = own_buf + strlen ("QPassSignals:");
      CORE_ADDR cursig;

      p = decode_address_to_semicolon (&cursig, p);
      for (i = 0; i < numsigs; i++)
	{
	  if (i == cursig)
	    {
	      cs.pass_signals[i] = 1;
	      if (*p == '\0')
		/* Keep looping, to clear the remaining signals.  */
		cursig = -1;
	      else
		p = decode_address_to_semicolon (&cursig, p);
	    }
	  else
	    cs.pass_signals[i] = 0;
	}
      strcpy (own_buf, "OK");
      return;
    }

  if (startswith (own_buf, "QProgramSignals:"))
    {
      int numsigs = (int) GDB_SIGNAL_LAST, i;
      const char *p = own_buf + strlen ("QProgramSignals:");
      CORE_ADDR cursig;

      cs.program_signals_p = 1;

      p = decode_address_to_semicolon (&cursig, p);
      for (i = 0; i < numsigs; i++)
	{
	  if (i == cursig)
	    {
	      cs.program_signals[i] = 1;
	      if (*p == '\0')
		/* Keep looping, to clear the remaining signals.  */
		cursig = -1;
	      else
		p = decode_address_to_semicolon (&cursig, p);
	    }
	  else
	    cs.program_signals[i] = 0;
	}
      strcpy (own_buf, "OK");
      return;
    }

  if (startswith (own_buf, "QCatchSyscalls:"))
    {
      const char *p = own_buf + sizeof ("QCatchSyscalls:") - 1;
      int enabled = -1;
      CORE_ADDR sysno;
      struct process_info *process;

      if (!target_running () || !target_supports_catch_syscall ())
	{
	  write_enn (own_buf);
	  return;
	}

      if (strcmp (p, "0") == 0)
	enabled = 0;
      else if (p[0] == '1' && (p[1] == ';' || p[1] == '\0'))
	enabled = 1;
      else
	{
	  fprintf (stderr, "Unknown catch-syscalls mode requested: %s\n",
		   own_buf);
	  write_enn (own_buf);
	  return;
	}

      process = current_process ();
      process->syscalls_to_catch.clear ();

      if (enabled)
	{
	  p += 1;
	  if (*p == ';')
	    {
	      p += 1;
	      while (*p != '\0')
		{
		  p = decode_address_to_semicolon (&sysno, p);
		  process->syscalls_to_catch.push_back (sysno);
		}
	    }
	  else
	    process->syscalls_to_catch.push_back (ANY_SYSCALL);
	}

      write_ok (own_buf);
      return;
    }

  if (strcmp (own_buf, "QEnvironmentReset") == 0)
    {
      our_environ = gdb_environ::from_host_environ ();

      write_ok (own_buf);
      return;
    }

  if (startswith (own_buf, "QEnvironmentHexEncoded:"))
    {
      const char *p = own_buf + sizeof ("QEnvironmentHexEncoded:") - 1;
      /* The final form of the environment variable.  FINAL_VAR will
	 hold the 'VAR=VALUE' format.  */
      std::string final_var = hex2str (p);
      std::string var_name, var_value;

      if (remote_debug)
	{
	  debug_printf (_("[QEnvironmentHexEncoded received '%s']\n"), p);
	  debug_printf (_("[Environment variable to be set: '%s']\n"),
			final_var.c_str ());
	  debug_flush ();
	}

      size_t pos = final_var.find ('=');
      if (pos == std::string::npos)
	{
	  warning (_("Unexpected format for environment variable: '%s'"),
		   final_var.c_str ());
	  write_enn (own_buf);
	  return;
	}

      var_name = final_var.substr (0, pos);
      var_value = final_var.substr (pos + 1, std::string::npos);

      our_environ.set (var_name.c_str (), var_value.c_str ());

      write_ok (own_buf);
      return;
    }

  if (startswith (own_buf, "QEnvironmentUnset:"))
    {
      const char *p = own_buf + sizeof ("QEnvironmentUnset:") - 1;
      std::string varname = hex2str (p);

      if (remote_debug)
	{
	  debug_printf (_("[QEnvironmentUnset received '%s']\n"), p);
	  debug_printf (_("[Environment variable to be unset: '%s']\n"),
			varname.c_str ());
	  debug_flush ();
	}

      our_environ.unset (varname.c_str ());

      write_ok (own_buf);
      return;
    }

  if (strcmp (own_buf, "QStartNoAckMode") == 0)
    {
      if (remote_debug)
	{
	  debug_printf ("[noack mode enabled]\n");
	  debug_flush ();
	}

      cs.noack_mode = 1;
      write_ok (own_buf);
      return;
    }

  if (startswith (own_buf, "QNonStop:"))
    {
      char *mode = own_buf + 9;
      int req = -1;
      const char *req_str;

      if (strcmp (mode, "0") == 0)
	req = 0;
      else if (strcmp (mode, "1") == 0)
	req = 1;
      else
	{
	  /* We don't know what this mode is, so complain to
	     GDB.  */
	  fprintf (stderr, "Unknown non-stop mode requested: %s\n",
		   own_buf);
	  write_enn (own_buf);
	  return;
	}

      req_str = req ? "non-stop" : "all-stop";
      if (the_target->start_non_stop (req == 1) != 0)
	{
	  fprintf (stderr, "Setting %s mode failed\n", req_str);
	  write_enn (own_buf);
	  return;
	}

      non_stop = (req != 0);

      if (remote_debug)
	debug_printf ("[%s mode enabled]\n", req_str);

      write_ok (own_buf);
      return;
    }

  if (startswith (own_buf, "QDisableRandomization:"))
    {
      char *packet = own_buf + strlen ("QDisableRandomization:");
      ULONGEST setting;

      unpack_varlen_hex (packet, &setting);
      cs.disable_randomization = setting;

      if (remote_debug)
	{
	  debug_printf (cs.disable_randomization
			? "[address space randomization disabled]\n"
			: "[address space randomization enabled]\n");
	}

      write_ok (own_buf);
      return;
    }

  if (target_supports_tracepoints ()
      && handle_tracepoint_general_set (own_buf))
    return;

  if (startswith (own_buf, "QAgent:"))
    {
      char *mode = own_buf + strlen ("QAgent:");
      int req = 0;

      if (strcmp (mode, "0") == 0)
	req = 0;
      else if (strcmp (mode, "1") == 0)
	req = 1;
      else
	{
	  /* We don't know what this value is, so complain to GDB.  */
	  sprintf (own_buf, "E.Unknown QAgent value");
	  return;
	}

      /* Update the flag.  */
      use_agent = req;
      if (remote_debug)
	debug_printf ("[%s agent]\n", req ? "Enable" : "Disable");
      write_ok (own_buf);
      return;
    }

  if (handle_btrace_general_set (own_buf))
    return;

  if (handle_btrace_conf_general_set (own_buf))
    return;

  if (startswith (own_buf, "QThreadEvents:"))
    {
      char *mode = own_buf + strlen ("QThreadEvents:");
      enum tribool req = TRIBOOL_UNKNOWN;

      if (strcmp (mode, "0") == 0)
	req = TRIBOOL_FALSE;
      else if (strcmp (mode, "1") == 0)
	req = TRIBOOL_TRUE;
      else
	{
	  /* We don't know what this mode is, so complain to GDB.  */
	  std::string err
	    = string_printf ("E.Unknown thread-events mode requested: %s\n",
			     mode);
	  strcpy (own_buf, err.c_str ());
	  return;
	}

      cs.report_thread_events = (req == TRIBOOL_TRUE);

      if (remote_debug)
	{
	  const char *req_str = cs.report_thread_events ? "enabled" : "disabled";

	  debug_printf ("[thread events are now %s]\n", req_str);
	}

      write_ok (own_buf);
      return;
    }

  if (startswith (own_buf, "QStartupWithShell:"))
    {
      const char *value = own_buf + strlen ("QStartupWithShell:");

      if (strcmp (value, "1") == 0)
	startup_with_shell = true;
      else if (strcmp (value, "0") == 0)
	startup_with_shell = false;
      else
	{
	  /* Unknown value.  */
	  fprintf (stderr, "Unknown value to startup-with-shell: %s\n",
		   own_buf);
	  write_enn (own_buf);
	  return;
	}

      if (remote_debug)
	debug_printf (_("[Inferior will %s started with shell]"),
		      startup_with_shell ? "be" : "not be");

      write_ok (own_buf);
      return;
    }

  if (startswith (own_buf, "QSetWorkingDir:"))
    {
      const char *p = own_buf + strlen ("QSetWorkingDir:");

      if (*p != '\0')
	{
	  std::string path = hex2str (p);

	  if (remote_debug)
	    debug_printf (_("[Set the inferior's current directory to %s]\n"),
			  path.c_str ());

	  set_inferior_cwd (std::move (path));
	}
      else
	{
	  /* An empty argument means that we should clear out any
	     previously set cwd for the inferior.  */
	  set_inferior_cwd ("");

	  if (remote_debug)
	    debug_printf (_("\
[Unset the inferior's current directory; will use gdbserver's cwd]\n"));
	}
      write_ok (own_buf);

      return;
    }


  /* Handle store memory tags packets.  */
  if (startswith (own_buf, "QMemTags:")
      && target_supports_memory_tagging ())
    {
      gdb::byte_vector tags;
      CORE_ADDR addr = 0;
      size_t len = 0;
      int type = 0;

      require_running_or_return (own_buf);

      bool ret = parse_store_memtags_request (own_buf, &addr, &len, tags,
					     &type);

      if (ret)
	ret = the_target->store_memtags (addr, len, tags, type);

      if (!ret)
	write_enn (own_buf);
      else
	write_ok (own_buf);

      return;
    }

  /* Otherwise we didn't know what packet it was.  Say we didn't
     understand it.  */
  own_buf[0] = 0;
}

static const char *
get_features_xml (const char *annex)
{
  const struct target_desc *desc = current_target_desc ();

  /* `desc->xmltarget' defines what to return when looking for the
     "target.xml" file.  Its contents can either be verbatim XML code
     (prefixed with a '@') or else the name of the actual XML file to
     be used in place of "target.xml".

     This variable is set up from the auto-generated
     init_registers_... routine for the current target.  */

  if (strcmp (annex, "target.xml") == 0)
    {
      const char *ret = tdesc_get_features_xml (desc);

      if (*ret == '@')
	return ret + 1;
      else
	annex = ret;
    }

#ifdef USE_XML
  {
    int i;

    /* Look for the annex.  */
    for (i = 0; xml_builtin[i][0] != NULL; i++)
      if (strcmp (annex, xml_builtin[i][0]) == 0)
	break;

    if (xml_builtin[i][0] != NULL)
      return xml_builtin[i][1];
  }
#endif

  return NULL;
}

static void
monitor_show_help (void)
{
  monitor_output ("The following monitor commands are supported:\n");
  monitor_output ("  set debug <0|1>\n");
  monitor_output ("    Enable general debugging messages\n");
  monitor_output ("  set debug-hw-points <0|1>\n");
  monitor_output ("    Enable h/w breakpoint/watchpoint debugging messages\n");
  monitor_output ("  set remote-debug <0|1>\n");
  monitor_output ("    Enable remote protocol debugging messages\n");
  monitor_output ("  set event-loop-debug <0|1>\n");
  monitor_output ("    Enable event loop debugging messages\n");
  monitor_output ("  set debug-format option1[,option2,...]\n");
  monitor_output ("    Add additional information to debugging messages\n");
  monitor_output ("    Options: all, none");
  monitor_output (", timestamp");
  monitor_output ("\n");
  monitor_output ("  exit\n");
  monitor_output ("    Quit GDBserver\n");
}

/* Read trace frame or inferior memory.  Returns the number of bytes
   actually read, zero when no further transfer is possible, and -1 on
   error.  Return of a positive value smaller than LEN does not
   indicate there's no more to be read, only the end of the transfer.
   E.g., when GDB reads memory from a traceframe, a first request may
   be served from a memory block that does not cover the whole request
   length.  A following request gets the rest served from either
   another block (of the same traceframe) or from the read-only
   regions.  */

static int
gdb_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
{
  client_state &cs = get_client_state ();
  int res;

  if (cs.current_traceframe >= 0)
    {
      ULONGEST nbytes;
      ULONGEST length = len;

      if (traceframe_read_mem (cs.current_traceframe,
			       memaddr, myaddr, len, &nbytes))
	return -1;
      /* Data read from trace buffer, we're done.  */
      if (nbytes > 0)
	return nbytes;
      if (!in_readonly_region (memaddr, length))
	return -1;
      /* Otherwise we have a valid readonly case, fall through.  */
      /* (assume no half-trace half-real blocks for now) */
    }

  res = prepare_to_access_memory ();
  if (res == 0)
    {
      if (set_desired_thread ())
	res = read_inferior_memory (memaddr, myaddr, len);
      else
	res = 1;
      done_accessing_memory ();

      return res == 0 ? len : -1;
    }
  else
    return -1;
}

/* Write trace frame or inferior memory.  Actually, writing to trace
   frames is forbidden.  */

static int
gdb_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
{
  client_state &cs = get_client_state ();
  if (cs.current_traceframe >= 0)
    return EIO;
  else
    {
      int ret;

      ret = prepare_to_access_memory ();
      if (ret == 0)
	{
	  if (set_desired_thread ())
	    ret = target_write_memory (memaddr, myaddr, len);
	  else
	    ret = EIO;
	  done_accessing_memory ();
	}
      return ret;
    }
}

/* Handle qSearch:memory packets.  */

static void
handle_search_memory (char *own_buf, int packet_len)
{
  CORE_ADDR start_addr;
  CORE_ADDR search_space_len;
  gdb_byte *pattern;
  unsigned int pattern_len;
  int found;
  CORE_ADDR found_addr;
  int cmd_name_len = sizeof ("qSearch:memory:") - 1;

  pattern = (gdb_byte *) malloc (packet_len);
  if (pattern == NULL)
    error ("Unable to allocate memory to perform the search");

  if (decode_search_memory_packet (own_buf + cmd_name_len,
				   packet_len - cmd_name_len,
				   &start_addr, &search_space_len,
				   pattern, &pattern_len) < 0)
    {
      free (pattern);
      error ("Error in parsing qSearch:memory packet");
    }

  auto read_memory = [] (CORE_ADDR addr, gdb_byte *result, size_t len)
    {
      return gdb_read_memory (addr, result, len) == len;
    };

  found = simple_search_memory (read_memory, start_addr, search_space_len,
				pattern, pattern_len, &found_addr);

  if (found > 0)
    sprintf (own_buf, "1,%lx", (long) found_addr);
  else if (found == 0)
    strcpy (own_buf, "0");
  else
    strcpy (own_buf, "E00");

  free (pattern);
}

/* Handle the "D" packet.  */

static void
handle_detach (char *own_buf)
{
  client_state &cs = get_client_state ();

  process_info *process;

  if (cs.multi_process)
    {
      /* skip 'D;' */
      int pid = strtol (&own_buf[2], NULL, 16);

      process = find_process_pid (pid);
    }
  else
    {
      process = (current_thread != nullptr
		 ? get_thread_process (current_thread)
		 : nullptr);
    }

  if (process == NULL)
    {
      write_enn (own_buf);
      return;
    }

  if ((tracing && disconnected_tracing) || any_persistent_commands (process))
    {
      if (tracing && disconnected_tracing)
	fprintf (stderr,
		 "Disconnected tracing in effect, "
		 "leaving gdbserver attached to the process\n");

      if (any_persistent_commands (process))
	fprintf (stderr,
		 "Persistent commands are present, "
		 "leaving gdbserver attached to the process\n");

      /* Make sure we're in non-stop/async mode, so we we can both
	 wait for an async socket accept, and handle async target
	 events simultaneously.  There's also no point either in
	 having the target stop all threads, when we're going to
	 pass signals down without informing GDB.  */
      if (!non_stop)
	{
	  if (debug_threads)
	    debug_printf ("Forcing non-stop mode\n");

	  non_stop = true;
	  the_target->start_non_stop (true);
	}

      process->gdb_detached = 1;

      /* Detaching implicitly resumes all threads.  */
      target_continue_no_signal (minus_one_ptid);

      write_ok (own_buf);
      return;
    }

  fprintf (stderr, "Detaching from process %d\n", process->pid);
  stop_tracing ();

  /* We'll need this after PROCESS has been destroyed.  */
  int pid = process->pid;

  if (detach_inferior (process) != 0)
    write_enn (own_buf);
  else
    {
      discard_queued_stop_replies (ptid_t (pid));
      write_ok (own_buf);

      if (extended_protocol || target_running ())
	{
	  /* There is still at least one inferior remaining or
	     we are in extended mode, so don't terminate gdbserver,
	     and instead treat this like a normal program exit.  */
	  cs.last_status.kind = TARGET_WAITKIND_EXITED;
	  cs.last_status.value.integer = 0;
	  cs.last_ptid = ptid_t (pid);

	  current_thread = NULL;
	}
      else
	{
	  putpkt (own_buf);
	  remote_close ();

	  /* If we are attached, then we can exit.  Otherwise, we
	     need to hang around doing nothing, until the child is
	     gone.  */
	  join_inferior (pid);
	  exit (0);
	}
    }
}

/* Parse options to --debug-format= and "monitor set debug-format".
   ARG is the text after "--debug-format=" or "monitor set debug-format".
   IS_MONITOR is non-zero if we're invoked via "monitor set debug-format".
   This triggers calls to monitor_output.
   The result is an empty string if all options were parsed ok, otherwise an
   error message which the caller must free.

   N.B. These commands affect all debug format settings, they are not
   cumulative.  If a format is not specified, it is turned off.
   However, we don't go to extra trouble with things like
   "monitor set debug-format all,none,timestamp".
   Instead we just parse them one at a time, in order.

   The syntax for "monitor set debug" we support here is not identical
   to gdb's "set debug foo on|off" because we also use this function to
   parse "--debug-format=foo,bar".  */

static std::string
parse_debug_format_options (const char *arg, int is_monitor)
{
  /* First turn all debug format options off.  */
  debug_timestamp = 0;

  /* First remove leading spaces, for "monitor set debug-format".  */
  while (isspace (*arg))
    ++arg;

  std::vector<gdb::unique_xmalloc_ptr<char>> options
    = delim_string_to_char_ptr_vec (arg, ',');

  for (const gdb::unique_xmalloc_ptr<char> &option : options)
    {
      if (strcmp (option.get (), "all") == 0)
	{
	  debug_timestamp = 1;
	  if (is_monitor)
	    monitor_output ("All extra debug format options enabled.\n");
	}
      else if (strcmp (option.get (), "none") == 0)
	{
	  debug_timestamp = 0;
	  if (is_monitor)
	    monitor_output ("All extra debug format options disabled.\n");
	}
      else if (strcmp (option.get (), "timestamp") == 0)
	{
	  debug_timestamp = 1;
	  if (is_monitor)
	    monitor_output ("Timestamps will be added to debug output.\n");
	}
      else if (*option == '\0')
	{
	  /* An empty option, e.g., "--debug-format=foo,,bar", is ignored.  */
	  continue;
	}
      else
	return string_printf ("Unknown debug-format argument: \"%s\"\n",
			      option.get ());
    }

  return std::string ();
}

/* Handle monitor commands not handled by target-specific handlers.  */

static void
handle_monitor_command (char *mon, char *own_buf)
{
  if (strcmp (mon, "set debug 1") == 0)
    {
      debug_threads = 1;
      monitor_output ("Debug output enabled.\n");
    }
  else if (strcmp (mon, "set debug 0") == 0)
    {
      debug_threads = 0;
      monitor_output ("Debug output disabled.\n");
    }
  else if (strcmp (mon, "set debug-hw-points 1") == 0)
    {
      show_debug_regs = 1;
      monitor_output ("H/W point debugging output enabled.\n");
    }
  else if (strcmp (mon, "set debug-hw-points 0") == 0)
    {
      show_debug_regs = 0;
      monitor_output ("H/W point debugging output disabled.\n");
    }
  else if (strcmp (mon, "set remote-debug 1") == 0)
    {
      remote_debug = 1;
      monitor_output ("Protocol debug output enabled.\n");
    }
  else if (strcmp (mon, "set remote-debug 0") == 0)
    {
      remote_debug = 0;
      monitor_output ("Protocol debug output disabled.\n");
    }
  else if (strcmp (mon, "set event-loop-debug 1") == 0)
    {
      debug_event_loop = debug_event_loop_kind::ALL;
      monitor_output ("Event loop debug output enabled.\n");
    }
  else if (strcmp (mon, "set event-loop-debug 0") == 0)
    {
      debug_event_loop = debug_event_loop_kind::OFF;
      monitor_output ("Event loop debug output disabled.\n");
    }
  else if (startswith (mon, "set debug-format "))
    {
      std::string error_msg
	= parse_debug_format_options (mon + sizeof ("set debug-format ") - 1,
				      1);

      if (!error_msg.empty ())
	{
	  monitor_output (error_msg.c_str ());
	  monitor_show_help ();
	  write_enn (own_buf);
	}
    }
  else if (strcmp (mon, "set debug-file") == 0)
    debug_set_output (nullptr);
  else if (startswith (mon, "set debug-file "))
    debug_set_output (mon + sizeof ("set debug-file ") - 1);
  else if (strcmp (mon, "help") == 0)
    monitor_show_help ();
  else if (strcmp (mon, "exit") == 0)
    exit_requested = true;
  else
    {
      monitor_output ("Unknown monitor command.\n\n");
      monitor_show_help ();
      write_enn (own_buf);
    }
}

/* Associates a callback with each supported qXfer'able object.  */

struct qxfer
{
  /* The object this handler handles.  */
  const char *object;

  /* Request that the target transfer up to LEN 8-bit bytes of the
     target's OBJECT.  The OFFSET, for a seekable object, specifies
     the starting point.  The ANNEX can be used to provide additional
     data-specific information to the target.

     Return the number of bytes actually transfered, zero when no
     further transfer is possible, -1 on error, -2 when the transfer
     is not supported, and -3 on a verbose error message that should
     be preserved.  Return of a positive value smaller than LEN does
     not indicate the end of the object, only the end of the transfer.

     One, and only one, of readbuf or writebuf must be non-NULL.  */
  int (*xfer) (const char *annex,
	       gdb_byte *readbuf, const gdb_byte *writebuf,
	       ULONGEST offset, LONGEST len);
};

/* Handle qXfer:auxv:read.  */

static int
handle_qxfer_auxv (const char *annex,
		   gdb_byte *readbuf, const gdb_byte *writebuf,
		   ULONGEST offset, LONGEST len)
{
  if (!the_target->supports_read_auxv () || writebuf != NULL)
    return -2;

  if (annex[0] != '\0' || current_thread == NULL)
    return -1;

  return the_target->read_auxv (offset, readbuf, len);
}

/* Handle qXfer:exec-file:read.  */

static int
handle_qxfer_exec_file (const char *annex,
			gdb_byte *readbuf, const gdb_byte *writebuf,
			ULONGEST offset, LONGEST len)
{
  ULONGEST pid;
  int total_len;

  if (!the_target->supports_pid_to_exec_file () || writebuf != NULL)
    return -2;

  if (annex[0] == '\0')
    {
      if (current_thread == NULL)
	return -1;

      pid = pid_of (current_thread);
    }
  else
    {
      annex = unpack_varlen_hex (annex, &pid);
      if (annex[0] != '\0')
	return -1;
    }

  if (pid <= 0)
    return -1;

  const char *file = the_target->pid_to_exec_file (pid);
  if (file == NULL)
    return -1;

  total_len = strlen (file);

  if (offset > total_len)
    return -1;

  if (offset + len > total_len)
    len = total_len - offset;

  memcpy (readbuf, file + offset, len);
  return len;
}

/* Handle qXfer:features:read.  */

static int
handle_qxfer_features (const char *annex,
		       gdb_byte *readbuf, const gdb_byte *writebuf,
		       ULONGEST offset, LONGEST len)
{
  const char *document;
  size_t total_len;

  if (writebuf != NULL)
    return -2;

  if (!target_running ())
    return -1;

  /* Grab the correct annex.  */
  document = get_features_xml (annex);
  if (document == NULL)
    return -1;

  total_len = strlen (document);

  if (offset > total_len)
    return -1;

  if (offset + len > total_len)
    len = total_len - offset;

  memcpy (readbuf, document + offset, len);
  return len;
}

/* Handle qXfer:libraries:read.  */

static int
handle_qxfer_libraries (const char *annex,
			gdb_byte *readbuf, const gdb_byte *writebuf,
			ULONGEST offset, LONGEST len)
{
  if (writebuf != NULL)
    return -2;

  if (annex[0] != '\0' || current_thread == NULL)
    return -1;

  std::string document = "<library-list version=\"1.0\">\n";

  process_info *proc = current_process ();
  for (const dll_info &dll : proc->all_dlls)
    document += string_printf
      ("  <library name=\"%s\"><segment address=\"0x%s\"/></library>\n",
       dll.name.c_str (), paddress (dll.base_addr));

  document += "</library-list>\n";

  if (offset > document.length ())
    return -1;

  if (offset + len > document.length ())
    len = document.length () - offset;

  memcpy (readbuf, &document[offset], len);

  return len;
}

/* Handle qXfer:libraries-svr4:read.  */

static int
handle_qxfer_libraries_svr4 (const char *annex,
			     gdb_byte *readbuf, const gdb_byte *writebuf,
			     ULONGEST offset, LONGEST len)
{
  if (writebuf != NULL)
    return -2;

  if (current_thread == NULL
      || !the_target->supports_qxfer_libraries_svr4 ())
    return -1;

  return the_target->qxfer_libraries_svr4 (annex, readbuf, writebuf,
					   offset, len);
}

/* Handle qXfer:osadata:read.  */

static int
handle_qxfer_osdata (const char *annex,
		     gdb_byte *readbuf, const gdb_byte *writebuf,
		     ULONGEST offset, LONGEST len)
{
  if (!the_target->supports_qxfer_osdata () || writebuf != NULL)
    return -2;

  return the_target->qxfer_osdata (annex, readbuf, NULL, offset, len);
}

/* Handle qXfer:siginfo:read and qXfer:siginfo:write.  */

static int
handle_qxfer_siginfo (const char *annex,
		      gdb_byte *readbuf, const gdb_byte *writebuf,
		      ULONGEST offset, LONGEST len)
{
  if (!the_target->supports_qxfer_siginfo ())
    return -2;

  if (annex[0] != '\0' || current_thread == NULL)
    return -1;

  return the_target->qxfer_siginfo (annex, readbuf, writebuf, offset, len);
}

/* Handle qXfer:statictrace:read.  */

static int
handle_qxfer_statictrace (const char *annex,
			  gdb_byte *readbuf, const gdb_byte *writebuf,
			  ULONGEST offset, LONGEST len)
{
  client_state &cs = get_client_state ();
  ULONGEST nbytes;

  if (writebuf != NULL)
    return -2;

  if (annex[0] != '\0' || current_thread == NULL 
      || cs.current_traceframe == -1)
    return -1;

  if (traceframe_read_sdata (cs.current_traceframe, offset,
			     readbuf, len, &nbytes))
    return -1;
  return nbytes;
}

/* Helper for handle_qxfer_threads_proper.
   Emit the XML to describe the thread of INF.  */

static void
handle_qxfer_threads_worker (thread_info *thread, struct buffer *buffer)
{
  ptid_t ptid = ptid_of (thread);
  char ptid_s[100];
  int core = target_core_of_thread (ptid);
  char core_s[21];
  const char *name = target_thread_name (ptid);
  int handle_len;
  gdb_byte *handle;
  bool handle_status = target_thread_handle (ptid, &handle, &handle_len);

  write_ptid (ptid_s, ptid);

  buffer_xml_printf (buffer, "<thread id=\"%s\"", ptid_s);

  if (core != -1)
    {
      sprintf (core_s, "%d", core);
      buffer_xml_printf (buffer, " core=\"%s\"", core_s);
    }

  if (name != NULL)
    buffer_xml_printf (buffer, " name=\"%s\"", name);

  if (handle_status)
    {
      char *handle_s = (char *) alloca (handle_len * 2 + 1);
      bin2hex (handle, handle_s, handle_len);
      buffer_xml_printf (buffer, " handle=\"%s\"", handle_s);
    }

  buffer_xml_printf (buffer, "/>\n");
}

/* Helper for handle_qxfer_threads.  Return true on success, false
   otherwise.  */

static bool
handle_qxfer_threads_proper (struct buffer *buffer)
{
  client_state &cs = get_client_state ();

  scoped_restore save_current_thread
    = make_scoped_restore (&current_thread);
  scoped_restore save_current_general_thread
    = make_scoped_restore (&cs.general_thread);

  buffer_grow_str (buffer, "<threads>\n");

  process_info *error_proc = find_process ([&] (process_info *process)
    {
      /* The target may need to access memory and registers (e.g. via
	 libthread_db) to fetch thread properties.  Prepare for memory
	 access here, so that we potentially pause threads just once
	 for all accesses.  Note that even if someday we stop needing
	 to pause threads to access memory, we will need to be able to
	 access registers, or other ptrace accesses like
	 PTRACE_GET_THREAD_AREA.  */

      /* Need to switch to each process in turn, because
	 prepare_to_access_memory prepares for an access in the
	 current process pointed to by general_thread.  */
      switch_to_process (process);
      cs.general_thread = current_thread->id;

      int res = prepare_to_access_memory ();
      if (res == 0)
	{
	  for_each_thread (process->pid, [&] (thread_info *thread)
	    {
	      handle_qxfer_threads_worker (thread, buffer);
	    });

	  done_accessing_memory ();
	  return false;
	}
      else
	return true;
    });

  buffer_grow_str0 (buffer, "</threads>\n");
  return error_proc == nullptr;
}

/* Handle qXfer:threads:read.  */

static int
handle_qxfer_threads (const char *annex,
		      gdb_byte *readbuf, const gdb_byte *writebuf,
		      ULONGEST offset, LONGEST len)
{
  static char *result = 0;
  static unsigned int result_length = 0;

  if (writebuf != NULL)
    return -2;

  if (annex[0] != '\0')
    return -1;

  if (offset == 0)
    {
      struct buffer buffer;
      /* When asked for data at offset 0, generate everything and store into
	 'result'.  Successive reads will be served off 'result'.  */
      if (result)
	free (result);

      buffer_init (&buffer);

      bool res = handle_qxfer_threads_proper (&buffer);

      result = buffer_finish (&buffer);
      result_length = strlen (result);
      buffer_free (&buffer);

      if (!res)
	return -1;
    }

  if (offset >= result_length)
    {
      /* We're out of data.  */
      free (result);
      result = NULL;
      result_length = 0;
      return 0;
    }

  if (len > result_length - offset)
    len = result_length - offset;

  memcpy (readbuf, result + offset, len);

  return len;
}

/* Handle qXfer:traceframe-info:read.  */

static int
handle_qxfer_traceframe_info (const char *annex,
			      gdb_byte *readbuf, const gdb_byte *writebuf,
			      ULONGEST offset, LONGEST len)
{
  client_state &cs = get_client_state ();
  static char *result = 0;
  static unsigned int result_length = 0;

  if (writebuf != NULL)
    return -2;

  if (!target_running () || annex[0] != '\0' || cs.current_traceframe == -1)
    return -1;

  if (offset == 0)
    {
      struct buffer buffer;

      /* When asked for data at offset 0, generate everything and
	 store into 'result'.  Successive reads will be served off
	 'result'.  */
      free (result);

      buffer_init (&buffer);

      traceframe_read_info (cs.current_traceframe, &buffer);

      result = buffer_finish (&buffer);
      result_length = strlen (result);
      buffer_free (&buffer);
    }

  if (offset >= result_length)
    {
      /* We're out of data.  */
      free (result);
      result = NULL;
      result_length = 0;
      return 0;
    }

  if (len > result_length - offset)
    len = result_length - offset;

  memcpy (readbuf, result + offset, len);
  return len;
}

/* Handle qXfer:fdpic:read.  */

static int
handle_qxfer_fdpic (const char *annex, gdb_byte *readbuf,
		    const gdb_byte *writebuf, ULONGEST offset, LONGEST len)
{
  if (!the_target->supports_read_loadmap ())
    return -2;

  if (current_thread == NULL)
    return -1;

  return the_target->read_loadmap (annex, offset, readbuf, len);
}

/* Handle qXfer:btrace:read.  */

static int
handle_qxfer_btrace (const char *annex,
		     gdb_byte *readbuf, const gdb_byte *writebuf,
		     ULONGEST offset, LONGEST len)
{
  client_state &cs = get_client_state ();
  static struct buffer cache;
  struct thread_info *thread;
  enum btrace_read_type type;
  int result;

  if (writebuf != NULL)
    return -2;

  if (cs.general_thread == null_ptid
      || cs.general_thread == minus_one_ptid)
    {
      strcpy (cs.own_buf, "E.Must select a single thread.");
      return -3;
    }

  thread = find_thread_ptid (cs.general_thread);
  if (thread == NULL)
    {
      strcpy (cs.own_buf, "E.No such thread.");
      return -3;
    }

  if (thread->btrace == NULL)
    {
      strcpy (cs.own_buf, "E.Btrace not enabled.");
      return -3;
    }

  if (strcmp (annex, "all") == 0)
    type = BTRACE_READ_ALL;
  else if (strcmp (annex, "new") == 0)
    type = BTRACE_READ_NEW;
  else if (strcmp (annex, "delta") == 0)
    type = BTRACE_READ_DELTA;
  else
    {
      strcpy (cs.own_buf, "E.Bad annex.");
      return -3;
    }

  if (offset == 0)
    {
      buffer_free (&cache);

      try
	{
	  result = target_read_btrace (thread->btrace, &cache, type);
	  if (result != 0)
	    memcpy (cs.own_buf, cache.buffer, cache.used_size);
	}
      catch (const gdb_exception_error &exception)
	{
	  sprintf (cs.own_buf, "E.%s", exception.what ());
	  result = -1;
	}

      if (result != 0)
	return -3;
    }
  else if (offset > cache.used_size)
    {
      buffer_free (&cache);
      return -3;
    }

  if (len > cache.used_size - offset)
    len = cache.used_size - offset;

  memcpy (readbuf, cache.buffer + offset, len);

  return len;
}

/* Handle qXfer:btrace-conf:read.  */

static int
handle_qxfer_btrace_conf (const char *annex,
			  gdb_byte *readbuf, const gdb_byte *writebuf,
			  ULONGEST offset, LONGEST len)
{
  client_state &cs = get_client_state ();
  static struct buffer cache;
  struct thread_info *thread;
  int result;

  if (writebuf != NULL)
    return -2;

  if (annex[0] != '\0')
    return -1;

  if (cs.general_thread == null_ptid
      || cs.general_thread == minus_one_ptid)
    {
      strcpy (cs.own_buf, "E.Must select a single thread.");
      return -3;
    }

  thread = find_thread_ptid (cs.general_thread);
  if (thread == NULL)
    {
      strcpy (cs.own_buf, "E.No such thread.");
      return -3;
    }

  if (thread->btrace == NULL)
    {
      strcpy (cs.own_buf, "E.Btrace not enabled.");
      return -3;
    }

  if (offset == 0)
    {
      buffer_free (&cache);

      try
	{
	  result = target_read_btrace_conf (thread->btrace, &cache);
	  if (result != 0)
	    memcpy (cs.own_buf, cache.buffer, cache.used_size);
	}
      catch (const gdb_exception_error &exception)
	{
	  sprintf (cs.own_buf, "E.%s", exception.what ());
	  result = -1;
	}

      if (result != 0)
	return -3;
    }
  else if (offset > cache.used_size)
    {
      buffer_free (&cache);
      return -3;
    }

  if (len > cache.used_size - offset)
    len = cache.used_size - offset;

  memcpy (readbuf, cache.buffer + offset, len);

  return len;
}

static const struct qxfer qxfer_packets[] =
  {
    { "auxv", handle_qxfer_auxv },
    { "btrace", handle_qxfer_btrace },
    { "btrace-conf", handle_qxfer_btrace_conf },
    { "exec-file", handle_qxfer_exec_file},
    { "fdpic", handle_qxfer_fdpic},
    { "features", handle_qxfer_features },
    { "libraries", handle_qxfer_libraries },
    { "libraries-svr4", handle_qxfer_libraries_svr4 },
    { "osdata", handle_qxfer_osdata },
    { "siginfo", handle_qxfer_siginfo },
    { "statictrace", handle_qxfer_statictrace },
    { "threads", handle_qxfer_threads },
    { "traceframe-info", handle_qxfer_traceframe_info },
  };

static int
handle_qxfer (char *own_buf, int packet_len, int *new_packet_len_p)
{
  int i;
  char *object;
  char *rw;
  char *annex;
  char *offset;

  if (!startswith (own_buf, "qXfer:"))
    return 0;

  /* Grab the object, r/w and annex.  */
  if (decode_xfer (own_buf + 6, &object, &rw, &annex, &offset) < 0)
    {
      write_enn (own_buf);
      return 1;
    }

  for (i = 0;
       i < sizeof (qxfer_packets) / sizeof (qxfer_packets[0]);
       i++)
    {
      const struct qxfer *q = &qxfer_packets[i];

      if (strcmp (object, q->object) == 0)
	{
	  if (strcmp (rw, "read") == 0)
	    {
	      unsigned char *data;
	      int n;
	      CORE_ADDR ofs;
	      unsigned int len;

	      /* Grab the offset and length.  */
	      if (decode_xfer_read (offset, &ofs, &len) < 0)
		{
		  write_enn (own_buf);
		  return 1;
		}

	      /* Read one extra byte, as an indicator of whether there is
		 more.  */
	      if (len > PBUFSIZ - 2)
		len = PBUFSIZ - 2;
	      data = (unsigned char *) malloc (len + 1);
	      if (data == NULL)
		{
		  write_enn (own_buf);
		  return 1;
		}
	      n = (*q->xfer) (annex, data, NULL, ofs, len + 1);
	      if (n == -2)
		{
		  free (data);
		  return 0;
		}
	      else if (n == -3)
		{
		  /* Preserve error message.  */
		}
	      else if (n < 0)
		write_enn (own_buf);
	      else if (n > len)
		*new_packet_len_p = write_qxfer_response (own_buf, data, len, 1);
	      else
		*new_packet_len_p = write_qxfer_response (own_buf, data, n, 0);

	      free (data);
	      return 1;
	    }
	  else if (strcmp (rw, "write") == 0)
	    {
	      int n;
	      unsigned int len;
	      CORE_ADDR ofs;
	      unsigned char *data;

	      strcpy (own_buf, "E00");
	      data = (unsigned char *) malloc (packet_len - (offset - own_buf));
	      if (data == NULL)
		{
		  write_enn (own_buf);
		  return 1;
		}
	      if (decode_xfer_write (offset, packet_len - (offset - own_buf),
				     &ofs, &len, data) < 0)
		{
		  free (data);
		  write_enn (own_buf);
		  return 1;
		}

	      n = (*q->xfer) (annex, NULL, data, ofs, len);
	      if (n == -2)
		{
		  free (data);
		  return 0;
		}
	      else if (n == -3)
		{
		  /* Preserve error message.  */
		}
	      else if (n < 0)
		write_enn (own_buf);
	      else
		sprintf (own_buf, "%x", n);

	      free (data);
	      return 1;
	    }

	  return 0;
	}
    }

  return 0;
}

/* Compute 32 bit CRC from inferior memory.

   On success, return 32 bit CRC.
   On failure, return (unsigned long long) -1.  */

static unsigned long long
crc32 (CORE_ADDR base, int len, unsigned int crc)
{
  while (len--)
    {
      unsigned char byte = 0;

      /* Return failure if memory read fails.  */
      if (read_inferior_memory (base, &byte, 1) != 0)
	return (unsigned long long) -1;

      crc = xcrc32 (&byte, 1, crc);
      base++;
    }
  return (unsigned long long) crc;
}

/* Parse the qMemTags packet request into ADDR and LEN.  */

static void
parse_fetch_memtags_request (char *request, CORE_ADDR *addr, size_t *len,
			     int *type)
{
  gdb_assert (startswith (request, "qMemTags:"));

  const char *p = request + strlen ("qMemTags:");

  /* Read address and length.  */
  unsigned int length = 0;
  p = decode_m_packet_params (p, addr, &length, ':');
  *len = length;

  /* Read the tag type.  */
  ULONGEST tag_type = 0;
  p = unpack_varlen_hex (p, &tag_type);
  *type = (int) tag_type;
}

/* Add supported btrace packets to BUF.  */

static void
supported_btrace_packets (char *buf)
{
  strcat (buf, ";Qbtrace:bts+");
  strcat (buf, ";Qbtrace-conf:bts:size+");
  strcat (buf, ";Qbtrace:pt+");
  strcat (buf, ";Qbtrace-conf:pt:size+");
  strcat (buf, ";Qbtrace:off+");
  strcat (buf, ";qXfer:btrace:read+");
  strcat (buf, ";qXfer:btrace-conf:read+");
}

/* Handle all of the extended 'q' packets.  */

static void
handle_query (char *own_buf, int packet_len, int *new_packet_len_p)
{
  client_state &cs = get_client_state ();
  static std::list<thread_info *>::const_iterator thread_iter;

  /* Reply the current thread id.  */
  if (strcmp ("qC", own_buf) == 0 && !disable_packet_qC)
    {
      ptid_t ptid;
      require_running_or_return (own_buf);

      if (cs.general_thread != null_ptid && cs.general_thread != minus_one_ptid)
	ptid = cs.general_thread;
      else
	{
	  thread_iter = all_threads.begin ();
	  ptid = (*thread_iter)->id;
	}

      sprintf (own_buf, "QC");
      own_buf += 2;
      write_ptid (own_buf, ptid);
      return;
    }

  if (strcmp ("qSymbol::", own_buf) == 0)
    {
      struct thread_info *save_thread = current_thread;

      /* For qSymbol, GDB only changes the current thread if the
	 previous current thread was of a different process.  So if
	 the previous thread is gone, we need to pick another one of
	 the same process.  This can happen e.g., if we followed an
	 exec in a non-leader thread.  */
      if (current_thread == NULL)
	{
	  current_thread
	    = find_any_thread_of_pid (cs.general_thread.pid ());

	  /* Just in case, if we didn't find a thread, then bail out
	     instead of crashing.  */
	  if (current_thread == NULL)
	    {
	      write_enn (own_buf);
	      current_thread = save_thread;
	      return;
	    }
	}

      /* GDB is suggesting new symbols have been loaded.  This may
	 mean a new shared library has been detected as loaded, so
	 take the opportunity to check if breakpoints we think are
	 inserted, still are.  Note that it isn't guaranteed that
	 we'll see this when a shared library is loaded, and nor will
	 we see this for unloads (although breakpoints in unloaded
	 libraries shouldn't trigger), as GDB may not find symbols for
	 the library at all.  We also re-validate breakpoints when we
	 see a second GDB breakpoint for the same address, and or when
	 we access breakpoint shadows.  */
      validate_breakpoints ();

      if (target_supports_tracepoints ())
	tracepoint_look_up_symbols ();

      if (current_thread != NULL)
	the_target->look_up_symbols ();

      current_thread = save_thread;

      strcpy (own_buf, "OK");
      return;
    }

  if (!disable_packet_qfThreadInfo)
    {
      if (strcmp ("qfThreadInfo", own_buf) == 0)
	{
	  require_running_or_return (own_buf);
	  thread_iter = all_threads.begin ();

	  *own_buf++ = 'm';
	  ptid_t ptid = (*thread_iter)->id;
	  write_ptid (own_buf, ptid);
	  thread_iter++;
	  return;
	}

      if (strcmp ("qsThreadInfo", own_buf) == 0)
	{
	  require_running_or_return (own_buf);
	  if (thread_iter != all_threads.end ())
	    {
	      *own_buf++ = 'm';
	      ptid_t ptid = (*thread_iter)->id;
	      write_ptid (own_buf, ptid);
	      thread_iter++;
	      return;
	    }
	  else
	    {
	      sprintf (own_buf, "l");
	      return;
	    }
	}
    }

  if (the_target->supports_read_offsets ()
      && strcmp ("qOffsets", own_buf) == 0)
    {
      CORE_ADDR text, data;

      require_running_or_return (own_buf);
      if (the_target->read_offsets (&text, &data))
	sprintf (own_buf, "Text=%lX;Data=%lX;Bss=%lX",
		 (long)text, (long)data, (long)data);
      else
	write_enn (own_buf);

      return;
    }

  /* Protocol features query.  */
  if (startswith (own_buf, "qSupported")
      && (own_buf[10] == ':' || own_buf[10] == '\0'))
    {
      char *p = &own_buf[10];
      int gdb_supports_qRelocInsn = 0;

      /* Process each feature being provided by GDB.  The first
	 feature will follow a ':', and latter features will follow
	 ';'.  */
      if (*p == ':')
	{
	  std::vector<std::string> qsupported;
	  std::vector<const char *> unknowns;

	  /* Two passes, to avoid nested strtok calls in
	     target_process_qsupported.  */
	  char *saveptr;
	  for (p = strtok_r (p + 1, ";", &saveptr);
	       p != NULL;
	       p = strtok_r (NULL, ";", &saveptr))
	    qsupported.emplace_back (p);

	  for (const std::string &feature : qsupported)
	    {
	      if (feature == "multiprocess+")
		{
		  /* GDB supports and wants multi-process support if
		     possible.  */
		  if (target_supports_multi_process ())
		    cs.multi_process = 1;
		}
	      else if (feature == "qRelocInsn+")
		{
		  /* GDB supports relocate instruction requests.  */
		  gdb_supports_qRelocInsn = 1;
		}
	      else if (feature == "swbreak+")
		{
		  /* GDB wants us to report whether a trap is caused
		     by a software breakpoint and for us to handle PC
		     adjustment if necessary on this target.  */
		  if (target_supports_stopped_by_sw_breakpoint ())
		    cs.swbreak_feature = 1;
		}
	      else if (feature == "hwbreak+")
		{
		  /* GDB wants us to report whether a trap is caused
		     by a hardware breakpoint.  */
		  if (target_supports_stopped_by_hw_breakpoint ())
		    cs.hwbreak_feature = 1;
		}
	      else if (feature == "fork-events+")
		{
		  /* GDB supports and wants fork events if possible.  */
		  if (target_supports_fork_events ())
		    cs.report_fork_events = 1;
		}
	      else if (feature == "vfork-events+")
		{
		  /* GDB supports and wants vfork events if possible.  */
		  if (target_supports_vfork_events ())
		    cs.report_vfork_events = 1;
		}
	      else if (feature == "exec-events+")
		{
		  /* GDB supports and wants exec events if possible.  */
		  if (target_supports_exec_events ())
		    cs.report_exec_events = 1;
		}
	      else if (feature == "vContSupported+")
		cs.vCont_supported = 1;
	      else if (feature == "QThreadEvents+")
		;
	      else if (feature == "no-resumed+")
		{
		  /* GDB supports and wants TARGET_WAITKIND_NO_RESUMED
		     events.  */
		  report_no_resumed = true;
		}
	      else if (feature == "memory-tagging+")
		{
		  /* GDB supports memory tagging features.  */
		  if (target_supports_memory_tagging ())
		    cs.memory_tagging_feature = true;
		}
	      else
		{
		  /* Move the unknown features all together.  */
		  unknowns.push_back (feature.c_str ());
		}
	    }

	  /* Give the target backend a chance to process the unknown
	     features.  */
	  target_process_qsupported (unknowns);
	}

      sprintf (own_buf,
	       "PacketSize=%x;QPassSignals+;QProgramSignals+;"
	       "QStartupWithShell+;QEnvironmentHexEncoded+;"
	       "QEnvironmentReset+;QEnvironmentUnset+;"
	       "QSetWorkingDir+",
	       PBUFSIZ - 1);

      if (target_supports_catch_syscall ())
	strcat (own_buf, ";QCatchSyscalls+");

      if (the_target->supports_qxfer_libraries_svr4 ())
	strcat (own_buf, ";qXfer:libraries-svr4:read+"
		";augmented-libraries-svr4-read+");
      else
	{
	  /* We do not have any hook to indicate whether the non-SVR4 target
	     backend supports qXfer:libraries:read, so always report it.  */
	  strcat (own_buf, ";qXfer:libraries:read+");
	}

      if (the_target->supports_read_auxv ())
	strcat (own_buf, ";qXfer:auxv:read+");

      if (the_target->supports_qxfer_siginfo ())
	strcat (own_buf, ";qXfer:siginfo:read+;qXfer:siginfo:write+");

      if (the_target->supports_read_loadmap ())
	strcat (own_buf, ";qXfer:fdpic:read+");

      /* We always report qXfer:features:read, as targets may
	 install XML files on a subsequent call to arch_setup.
	 If we reported to GDB on startup that we don't support
	 qXfer:feature:read at all, we will never be re-queried.  */
      strcat (own_buf, ";qXfer:features:read+");

      if (cs.transport_is_reliable)
	strcat (own_buf, ";QStartNoAckMode+");

      if (the_target->supports_qxfer_osdata ())
	strcat (own_buf, ";qXfer:osdata:read+");

      if (target_supports_multi_process ())
	strcat (own_buf, ";multiprocess+");

      if (target_supports_fork_events ())
	strcat (own_buf, ";fork-events+");

      if (target_supports_vfork_events ())
	strcat (own_buf, ";vfork-events+");

      if (target_supports_exec_events ())
	strcat (own_buf, ";exec-events+");

      if (target_supports_non_stop ())
	strcat (own_buf, ";QNonStop+");

      if (target_supports_disable_randomization ())
	strcat (own_buf, ";QDisableRandomization+");

      strcat (own_buf, ";qXfer:threads:read+");

      if (target_supports_tracepoints ())
	{
	  strcat (own_buf, ";ConditionalTracepoints+");
	  strcat (own_buf, ";TraceStateVariables+");
	  strcat (own_buf, ";TracepointSource+");
	  strcat (own_buf, ";DisconnectedTracing+");
	  if (gdb_supports_qRelocInsn && target_supports_fast_tracepoints ())
	    strcat (own_buf, ";FastTracepoints+");
	  strcat (own_buf, ";StaticTracepoints+");
	  strcat (own_buf, ";InstallInTrace+");
	  strcat (own_buf, ";qXfer:statictrace:read+");
	  strcat (own_buf, ";qXfer:traceframe-info:read+");
	  strcat (own_buf, ";EnableDisableTracepoints+");
	  strcat (own_buf, ";QTBuffer:size+");
	  strcat (own_buf, ";tracenz+");
	}

      if (target_supports_hardware_single_step ()
	  || target_supports_software_single_step () )
	{
	  strcat (own_buf, ";ConditionalBreakpoints+");
	}
      strcat (own_buf, ";BreakpointCommands+");

      if (target_supports_agent ())
	strcat (own_buf, ";QAgent+");

      supported_btrace_packets (own_buf);

      if (target_supports_stopped_by_sw_breakpoint ())
	strcat (own_buf, ";swbreak+");

      if (target_supports_stopped_by_hw_breakpoint ())
	strcat (own_buf, ";hwbreak+");

      if (the_target->supports_pid_to_exec_file ())
	strcat (own_buf, ";qXfer:exec-file:read+");

      strcat (own_buf, ";vContSupported+");

      strcat (own_buf, ";QThreadEvents+");

      strcat (own_buf, ";no-resumed+");

      if (target_supports_memory_tagging ())
	strcat (own_buf, ";memory-tagging+");

      /* Reinitialize components as needed for the new connection.  */
      hostio_handle_new_gdb_connection ();
      target_handle_new_gdb_connection ();

      return;
    }

  /* Thread-local storage support.  */
  if (the_target->supports_get_tls_address ()
      && startswith (own_buf, "qGetTLSAddr:"))
    {
      char *p = own_buf + 12;
      CORE_ADDR parts[2], address = 0;
      int i, err;
      ptid_t ptid = null_ptid;

      require_running_or_return (own_buf);

      for (i = 0; i < 3; i++)
	{
	  char *p2;
	  int len;

	  if (p == NULL)
	    break;

	  p2 = strchr (p, ',');
	  if (p2)
	    {
	      len = p2 - p;
	      p2++;
	    }
	  else
	    {
	      len = strlen (p);
	      p2 = NULL;
	    }

	  if (i == 0)
	    ptid = read_ptid (p, NULL);
	  else
	    decode_address (&parts[i - 1], p, len);
	  p = p2;
	}

      if (p != NULL || i < 3)
	err = 1;
      else
	{
	  struct thread_info *thread = find_thread_ptid (ptid);

	  if (thread == NULL)
	    err = 2;
	  else
	    err = the_target->get_tls_address (thread, parts[0], parts[1],
					       &address);
	}

      if (err == 0)
	{
	  strcpy (own_buf, paddress(address));
	  return;
	}
      else if (err > 0)
	{
	  write_enn (own_buf);
	  return;
	}

      /* Otherwise, pretend we do not understand this packet.  */
    }

  /* Windows OS Thread Information Block address support.  */
  if (the_target->supports_get_tib_address ()
      && startswith (own_buf, "qGetTIBAddr:"))
    {
      const char *annex;
      int n;
      CORE_ADDR tlb;
      ptid_t ptid = read_ptid (own_buf + 12, &annex);

      n = the_target->get_tib_address (ptid, &tlb);
      if (n == 1)
	{
	  strcpy (own_buf, paddress(tlb));
	  return;
	}
      else if (n == 0)
	{
	  write_enn (own_buf);
	  return;
	}
      return;
    }

  /* Handle "monitor" commands.  */
  if (startswith (own_buf, "qRcmd,"))
    {
      char *mon = (char *) malloc (PBUFSIZ);
      int len = strlen (own_buf + 6);

      if (mon == NULL)
	{
	  write_enn (own_buf);
	  return;
	}

      if ((len % 2) != 0
	  || hex2bin (own_buf + 6, (gdb_byte *) mon, len / 2) != len / 2)
	{
	  write_enn (own_buf);
	  free (mon);
	  return;
	}
      mon[len / 2] = '\0';

      write_ok (own_buf);

      if (the_target->handle_monitor_command (mon) == 0)
	/* Default processing.  */
	handle_monitor_command (mon, own_buf);

      free (mon);
      return;
    }

  if (startswith (own_buf, "qSearch:memory:"))
    {
      require_running_or_return (own_buf);
      handle_search_memory (own_buf, packet_len);
      return;
    }

  if (strcmp (own_buf, "qAttached") == 0
      || startswith (own_buf, "qAttached:"))
    {
      struct process_info *process;

      if (own_buf[sizeof ("qAttached") - 1])
	{
	  int pid = strtoul (own_buf + sizeof ("qAttached:") - 1, NULL, 16);
	  process = find_process_pid (pid);
	}
      else
	{
	  require_running_or_return (own_buf);
	  process = current_process ();
	}

      if (process == NULL)
	{
	  write_enn (own_buf);
	  return;
	}

      strcpy (own_buf, process->attached ? "1" : "0");
      return;
    }

  if (startswith (own_buf, "qCRC:"))
    {
      /* CRC check (compare-section).  */
      const char *comma;
      ULONGEST base;
      int len;
      unsigned long long crc;

      require_running_or_return (own_buf);
      comma = unpack_varlen_hex (own_buf + 5, &base);
      if (*comma++ != ',')
	{
	  write_enn (own_buf);
	  return;
	}
      len = strtoul (comma, NULL, 16);
      crc = crc32 (base, len, 0xffffffff);
      /* Check for memory failure.  */
      if (crc == (unsigned long long) -1)
	{
	  write_enn (own_buf);
	  return;
	}
      sprintf (own_buf, "C%lx", (unsigned long) crc);
      return;
    }

  if (handle_qxfer (own_buf, packet_len, new_packet_len_p))
    return;

  if (target_supports_tracepoints () && handle_tracepoint_query (own_buf))
    return;

  /* Handle fetch memory tags packets.  */
  if (startswith (own_buf, "qMemTags:")
      && target_supports_memory_tagging ())
    {
      gdb::byte_vector tags;
      CORE_ADDR addr = 0;
      size_t len = 0;
      int type = 0;

      require_running_or_return (own_buf);

      parse_fetch_memtags_request (own_buf, &addr, &len, &type);

      bool ret = the_target->fetch_memtags (addr, len, tags, type);

      if (ret)
	ret = create_fetch_memtags_reply (own_buf, tags);

      if (!ret)
	write_enn (own_buf);

      *new_packet_len_p = strlen (own_buf);
      return;
    }

  /* Otherwise we didn't know what packet it was.  Say we didn't
     understand it.  */
  own_buf[0] = 0;
}

static void gdb_wants_all_threads_stopped (void);
static void resume (struct thread_resume *actions, size_t n);

/* The callback that is passed to visit_actioned_threads.  */
typedef int (visit_actioned_threads_callback_ftype)
  (const struct thread_resume *, struct thread_info *);

/* Call CALLBACK for any thread to which ACTIONS applies to.  Returns
   true if CALLBACK returns true.  Returns false if no matching thread
   is found or CALLBACK results false.
   Note: This function is itself a callback for find_thread.  */

static bool
visit_actioned_threads (thread_info *thread,
			const struct thread_resume *actions,
			size_t num_actions,
			visit_actioned_threads_callback_ftype *callback)
{
  for (size_t i = 0; i < num_actions; i++)
    {
      const struct thread_resume *action = &actions[i];

      if (action->thread == minus_one_ptid
	  || action->thread == thread->id
	  || ((action->thread.pid ()
	       == thread->id.pid ())
	      && action->thread.lwp () == -1))
	{
	  if ((*callback) (action, thread))
	    return true;
	}
    }

  return false;
}

/* Callback for visit_actioned_threads.  If the thread has a pending
   status to report, report it now.  */

static int
handle_pending_status (const struct thread_resume *resumption,
		       struct thread_info *thread)
{
  client_state &cs = get_client_state ();
  if (thread->status_pending_p)
    {
      thread->status_pending_p = 0;

      cs.last_status = thread->last_status;
      cs.last_ptid = thread->id;
      prepare_resume_reply (cs.own_buf, cs.last_ptid, &cs.last_status);
      return 1;
    }
  return 0;
}

/* Parse vCont packets.  */
static void
handle_v_cont (char *own_buf)
{
  const char *p;
  int n = 0, i = 0;
  struct thread_resume *resume_info;
  struct thread_resume default_action { null_ptid };

  /* Count the number of semicolons in the packet.  There should be one
     for every action.  */
  p = &own_buf[5];
  while (p)
    {
      n++;
      p++;
      p = strchr (p, ';');
    }

  resume_info = (struct thread_resume *) malloc (n * sizeof (resume_info[0]));
  if (resume_info == NULL)
    goto err;

  p = &own_buf[5];
  while (*p)
    {
      p++;

      memset (&resume_info[i], 0, sizeof resume_info[i]);

      if (p[0] == 's' || p[0] == 'S')
	resume_info[i].kind = resume_step;
      else if (p[0] == 'r')
	resume_info[i].kind = resume_step;
      else if (p[0] == 'c' || p[0] == 'C')
	resume_info[i].kind = resume_continue;
      else if (p[0] == 't')
	resume_info[i].kind = resume_stop;
      else
	goto err;

      if (p[0] == 'S' || p[0] == 'C')
	{
	  char *q;
	  int sig = strtol (p + 1, &q, 16);
	  if (p == q)
	    goto err;
	  p = q;

	  if (!gdb_signal_to_host_p ((enum gdb_signal) sig))
	    goto err;
	  resume_info[i].sig = gdb_signal_to_host ((enum gdb_signal) sig);
	}
      else if (p[0] == 'r')
	{
	  ULONGEST addr;

	  p = unpack_varlen_hex (p + 1, &addr);
	  resume_info[i].step_range_start = addr;

	  if (*p != ',')
	    goto err;

	  p = unpack_varlen_hex (p + 1, &addr);
	  resume_info[i].step_range_end = addr;
	}
      else
	{
	  p = p + 1;
	}

      if (p[0] == 0)
	{
	  resume_info[i].thread = minus_one_ptid;
	  default_action = resume_info[i];

	  /* Note: we don't increment i here, we'll overwrite this entry
	     the next time through.  */
	}
      else if (p[0] == ':')
	{
	  const char *q;
	  ptid_t ptid = read_ptid (p + 1, &q);

	  if (p == q)
	    goto err;
	  p = q;
	  if (p[0] != ';' && p[0] != 0)
	    goto err;

	  resume_info[i].thread = ptid;

	  i++;
	}
    }

  if (i < n)
    resume_info[i] = default_action;

  resume (resume_info, n);
  free (resume_info);
  return;

err:
  write_enn (own_buf);
  free (resume_info);
  return;
}

/* Resume target with ACTIONS, an array of NUM_ACTIONS elements.  */

static void
resume (struct thread_resume *actions, size_t num_actions)
{
  client_state &cs = get_client_state ();
  if (!non_stop)
    {
      /* Check if among the threads that GDB wants actioned, there's
	 one with a pending status to report.  If so, skip actually
	 resuming/stopping and report the pending event
	 immediately.  */

      thread_info *thread_with_status = find_thread ([&] (thread_info *thread)
	{
	  return visit_actioned_threads (thread, actions, num_actions,
					 handle_pending_status);
	});

      if (thread_with_status != NULL)
	return;

      enable_async_io ();
    }

  the_target->resume (actions, num_actions);

  if (non_stop)
    write_ok (cs.own_buf);
  else
    {
      cs.last_ptid = mywait (minus_one_ptid, &cs.last_status, 0, 1);

      if (cs.last_status.kind == TARGET_WAITKIND_NO_RESUMED
	  && !report_no_resumed)
	{
	  /* The client does not support this stop reply.  At least
	     return error.  */
	  sprintf (cs.own_buf, "E.No unwaited-for children left.");
	  disable_async_io ();
	  return;
	}

      if (cs.last_status.kind != TARGET_WAITKIND_EXITED
	  && cs.last_status.kind != TARGET_WAITKIND_SIGNALLED
	  && cs.last_status.kind != TARGET_WAITKIND_NO_RESUMED)
	current_thread->last_status = cs.last_status;

      /* From the client's perspective, all-stop mode always stops all
	 threads implicitly (and the target backend has already done
	 so by now).  Tag all threads as "want-stopped", so we don't
	 resume them implicitly without the client telling us to.  */
      gdb_wants_all_threads_stopped ();
      prepare_resume_reply (cs.own_buf, cs.last_ptid, &cs.last_status);
      disable_async_io ();

      if (cs.last_status.kind == TARGET_WAITKIND_EXITED
	  || cs.last_status.kind == TARGET_WAITKIND_SIGNALLED)
	target_mourn_inferior (cs.last_ptid);
    }
}

/* Attach to a new program.  */
static void
handle_v_attach (char *own_buf)
{
  client_state &cs = get_client_state ();
  int pid;

  pid = strtol (own_buf + 8, NULL, 16);
  if (pid != 0 && attach_inferior (pid) == 0)
    {
      /* Don't report shared library events after attaching, even if
	 some libraries are preloaded.  GDB will always poll the
	 library list.  Avoids the "stopped by shared library event"
	 notice on the GDB side.  */
      current_process ()->dlls_changed = false;

      if (non_stop)
	{
	  /* In non-stop, we don't send a resume reply.  Stop events
	     will follow up using the normal notification
	     mechanism.  */
	  write_ok (own_buf);
	}
      else
	prepare_resume_reply (own_buf, cs.last_ptid, &cs.last_status);
    }
  else
    write_enn (own_buf);
}

/* Run a new program.  */
static void
handle_v_run (char *own_buf)
{
  client_state &cs = get_client_state ();
  char *p, *next_p;
  std::vector<char *> new_argv;
  char *new_program_name = NULL;
  int i, new_argc;

  new_argc = 0;
  for (p = own_buf + strlen ("vRun;"); p && *p; p = strchr (p, ';'))
    {
      p++;
      new_argc++;
    }

  for (i = 0, p = own_buf + strlen ("vRun;"); *p; p = next_p, ++i)
    {
      next_p = strchr (p, ';');
      if (next_p == NULL)
	next_p = p + strlen (p);

      if (i == 0 && p == next_p)
	{
	  /* No program specified.  */
	  new_program_name = NULL;
	}
      else if (p == next_p)
	{
	  /* Empty argument.  */
	  new_argv.push_back (xstrdup (""));
	}
      else
	{
	  size_t len = (next_p - p) / 2;
	  /* ARG is the unquoted argument received via the RSP.  */
	  char *arg = (char *) xmalloc (len + 1);
	  /* FULL_ARGS will contain the quoted version of ARG.  */
	  char *full_arg = (char *) xmalloc ((len + 1) * 2);
	  /* These are pointers used to navigate the strings above.  */
	  char *tmp_arg = arg;
	  char *tmp_full_arg = full_arg;
	  int need_quote = 0;

	  hex2bin (p, (gdb_byte *) arg, len);
	  arg[len] = '\0';

	  while (*tmp_arg != '\0')
	    {
	      switch (*tmp_arg)
		{
		case '\n':
		  /* Quote \n.  */
		  *tmp_full_arg = '\'';
		  ++tmp_full_arg;
		  need_quote = 1;
		  break;

		case '\'':
		  /* Quote single quote.  */
		  *tmp_full_arg = '\\';
		  ++tmp_full_arg;
		  break;

		default:
		  break;
		}

	      *tmp_full_arg = *tmp_arg;
	      ++tmp_full_arg;
	      ++tmp_arg;
	    }

	  if (need_quote)
	    *tmp_full_arg++ = '\'';

	  /* Finish FULL_ARG and push it into the vector containing
	     the argv.  */
	  *tmp_full_arg = '\0';
	  if (i == 0)
	    new_program_name = full_arg;
	  else
	    new_argv.push_back (full_arg);
	  xfree (arg);
	}
      if (*next_p)
	next_p++;
    }

  if (new_program_name == NULL)
    {
      /* GDB didn't specify a program to run.  Use the program from the
	 last run with the new argument list.  */
      if (program_path.get () == NULL)
	{
	  write_enn (own_buf);
	  free_vector_argv (new_argv);
	  return;
	}
    }
  else
    program_path.set (gdb::unique_xmalloc_ptr<char> (new_program_name));

  /* Free the old argv and install the new one.  */
  free_vector_argv (program_args);
  program_args = new_argv;

  target_create_inferior (program_path.get (), program_args);

  if (cs.last_status.kind == TARGET_WAITKIND_STOPPED)
    {
      prepare_resume_reply (own_buf, cs.last_ptid, &cs.last_status);

      /* In non-stop, sending a resume reply doesn't set the general
	 thread, but GDB assumes a vRun sets it (this is so GDB can
	 query which is the main thread of the new inferior.  */
      if (non_stop)
	cs.general_thread = cs.last_ptid;
    }
  else
    write_enn (own_buf);
}

/* Kill process.  */
static void
handle_v_kill (char *own_buf)
{
  client_state &cs = get_client_state ();
  int pid;
  char *p = &own_buf[6];
  if (cs.multi_process)
    pid = strtol (p, NULL, 16);
  else
    pid = signal_pid;

  process_info *proc = find_process_pid (pid);

  if (proc != nullptr && kill_inferior (proc) == 0)
    {
      cs.last_status.kind = TARGET_WAITKIND_SIGNALLED;
      cs.last_status.value.sig = GDB_SIGNAL_KILL;
      cs.last_ptid = ptid_t (pid);
      discard_queued_stop_replies (cs.last_ptid);
      write_ok (own_buf);
    }
  else
    write_enn (own_buf);
}

/* Handle all of the extended 'v' packets.  */
void
handle_v_requests (char *own_buf, int packet_len, int *new_packet_len)
{
  client_state &cs = get_client_state ();
  if (!disable_packet_vCont)
    {
      if (strcmp (own_buf, "vCtrlC") == 0)
	{
	  the_target->request_interrupt ();
	  write_ok (own_buf);
	  return;
	}

      if (startswith (own_buf, "vCont;"))
	{
	  handle_v_cont (own_buf);
	  return;
	}

      if (startswith (own_buf, "vCont?"))
	{
	  strcpy (own_buf, "vCont;c;C;t");

	  if (target_supports_hardware_single_step ()
	      || target_supports_software_single_step ()
	      || !cs.vCont_supported)
	    {
	      /* If target supports single step either by hardware or by
		 software, add actions s and S to the list of supported
		 actions.  On the other hand, if GDB doesn't request the
		 supported vCont actions in qSupported packet, add s and
		 S to the list too.  */
	      own_buf = own_buf + strlen (own_buf);
	      strcpy (own_buf, ";s;S");
	    }

	  if (target_supports_range_stepping ())
	    {
	      own_buf = own_buf + strlen (own_buf);
	      strcpy (own_buf, ";r");
	    }
	  return;
	}
    }

  if (startswith (own_buf, "vFile:")
      && handle_vFile (own_buf, packet_len, new_packet_len))
    return;

  if (startswith (own_buf, "vAttach;"))
    {
      if ((!extended_protocol || !cs.multi_process) && target_running ())