/* Linux-specific functions to retrieve OS data.
   
   Copyright (C) 2009-2018 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 "common-defs.h"
#include "linux-osdata.h"

#include <sys/types.h>
#include <sys/sysinfo.h>
#include <ctype.h>
#include <utmp.h>
#include <time.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "xml-utils.h"
#include "buffer.h"
#include <dirent.h>
#include <sys/stat.h>
#include "filestuff.h"
#include <algorithm>

#define NAMELEN(dirent) strlen ((dirent)->d_name)

/* Define PID_T to be a fixed size that is at least as large as pid_t,
   so that reading pid values embedded in /proc works
   consistently.  */

typedef long long  PID_T;

/* Define TIME_T to be at least as large as time_t, so that reading
   time values embedded in /proc works consistently.  */

typedef long long TIME_T;

#define MAX_PID_T_STRLEN  (sizeof ("-9223372036854775808") - 1)

/* Returns the CPU core that thread PTID is currently running on.  */
					  
/* Compute and return the processor core of a given thread.  */

int
linux_common_core_of_thread (ptid_t ptid)
{
  char filename[sizeof ("/proc//task//stat") + 2 * MAX_PID_T_STRLEN];
  char *content = NULL;
  char *p;
  char *ts = 0;
  int content_read = 0;
  int i;
  int core;

  sprintf (filename, "/proc/%lld/task/%lld/stat",
	   (PID_T) ptid.pid (), (PID_T) ptid.lwp ());
  gdb_file_up f = gdb_fopen_cloexec (filename, "r");
  if (!f)
    return -1;

  for (;;)
    {
      int n;
      content = (char *) xrealloc (content, content_read + 1024);
      n = fread (content + content_read, 1, 1024, f.get ());
      content_read += n;
      if (n < 1024)
	{
	  content[content_read] = '\0';
	  break;
	}
    }

  /* ps command also relies on no trailing fields ever contain ')'.  */
  p = strrchr (content, ')');
  if (p != NULL)
    p++;

  /* If the first field after program name has index 0, then core number is
     the field with index 36.  There's no constant for that anywhere.  */
  if (p != NULL)
    p = strtok_r (p, " ", &ts);
  for (i = 0; p != NULL && i != 36; ++i)
    p = strtok_r (NULL, " ", &ts);

  if (p == NULL || sscanf (p, "%d", &core) == 0)
    core = -1;

  xfree (content);

  return core;
}

/* Finds the command-line of process PID and copies it into COMMAND.
   At most MAXLEN characters are copied.  If the command-line cannot
   be found, PID is copied into command in text-form.  */

static void
command_from_pid (char *command, int maxlen, PID_T pid)
{
  std::string stat_path = string_printf ("/proc/%lld/stat", pid);
  gdb_file_up fp = gdb_fopen_cloexec (stat_path, "r");
  
  command[0] = '\0';
 
  if (fp)
    {
      /* sizeof (cmd) should be greater or equal to TASK_COMM_LEN (in
	 include/linux/sched.h in the Linux kernel sources) plus two
	 (for the brackets).  */
      char cmd[18];
      PID_T stat_pid;
      int items_read = fscanf (fp.get (), "%lld %17s", &stat_pid, cmd);
	  
      if (items_read == 2 && pid == stat_pid)
	{
	  cmd[strlen (cmd) - 1] = '\0'; /* Remove trailing parenthesis.  */
	  strncpy (command, cmd + 1, maxlen); /* Ignore leading parenthesis.  */
	}
    }
  else
    {
      /* Return the PID if a /proc entry for the process cannot be found.  */
      snprintf (command, maxlen, "%lld", pid);
    }

  command[maxlen - 1] = '\0'; /* Ensure string is null-terminated.  */
}

/* Returns the command-line of the process with the given PID. The
   returned string needs to be freed using xfree after use.  */

static char *
commandline_from_pid (PID_T pid)
{
  std::string pathname = string_printf ("/proc/%lld/cmdline", pid);
  char *commandline = NULL;
  gdb_file_up f = gdb_fopen_cloexec (pathname, "r");

  if (f)
    {
      size_t len = 0;

      while (!feof (f.get ()))
	{
	  char buf[1024];
	  size_t read_bytes = fread (buf, 1, sizeof (buf), f.get ());
     
	  if (read_bytes)
	    {
	      commandline = (char *) xrealloc (commandline, len + read_bytes + 1);
	      memcpy (commandline + len, buf, read_bytes);
	      len += read_bytes;
	    }
	}

      if (commandline)
	{
	  size_t i;

	  /* Replace null characters with spaces.  */
	  for (i = 0; i < len; ++i)
	    if (commandline[i] == '\0')
	      commandline[i] = ' ';

	  commandline[len] = '\0';
	}
      else
	{
	  /* Return the command in square brackets if the command-line
	     is empty.  */
	  commandline = (char *) xmalloc (32);
	  commandline[0] = '[';
	  command_from_pid (commandline + 1, 31, pid);

	  len = strlen (commandline);
	  if (len < 31)
	    strcat (commandline, "]");
	}
    }

  return commandline;
}

/* Finds the user name for the user UID and copies it into USER.  At
   most MAXLEN characters are copied.  */

static void
user_from_uid (char *user, int maxlen, uid_t uid)
{
  struct passwd *pwentry = getpwuid (uid);
  
  if (pwentry)
    {
      strncpy (user, pwentry->pw_name, maxlen);
      /* Ensure that the user name is null-terminated.  */
      user[maxlen - 1] = '\0';
    }
  else
    user[0] = '\0';
}

/* Finds the owner of process PID and returns the user id in OWNER.
   Returns 0 if the owner was found, -1 otherwise.  */

static int
get_process_owner (uid_t *owner, PID_T pid)
{
  struct stat statbuf;
  char procentry[sizeof ("/proc/") + MAX_PID_T_STRLEN];

  sprintf (procentry, "/proc/%lld", pid);
  
  if (stat (procentry, &statbuf) == 0 && S_ISDIR (statbuf.st_mode))
    {
      *owner = statbuf.st_uid;
      return 0;
    }
  else
    return -1;
}

/* Find the CPU cores used by process PID and return them in CORES.
   CORES points to an array of NUM_CORES elements.  */

static int
get_cores_used_by_process (PID_T pid, int *cores, const int num_cores)
{
  char taskdir[sizeof ("/proc/") + MAX_PID_T_STRLEN + sizeof ("/task") - 1];
  DIR *dir;
  struct dirent *dp;
  int task_count = 0;

  sprintf (taskdir, "/proc/%lld/task", pid);
  dir = opendir (taskdir);
  if (dir)
    {
      while ((dp = readdir (dir)) != NULL)
	{
	  PID_T tid;
	  int core;

	  if (!isdigit (dp->d_name[0])
	      || NAMELEN (dp) > MAX_PID_T_STRLEN)
	    continue;

	  sscanf (dp->d_name, "%lld", &tid);
	  core = linux_common_core_of_thread (ptid_t ((pid_t) pid,
						      (pid_t) tid, 0));

	  if (core >= 0 && core < num_cores)
	    {
	      ++cores[core];
	      ++task_count;
	    }
	}

      closedir (dir);
    }

  return task_count;
}

static LONGEST
linux_xfer_osdata_processes (gdb_byte *readbuf,
			     ULONGEST offset, ULONGEST len)
{
  /* We make the process list snapshot when the object starts to be read.  */
  static const char *buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      DIR *dirp;

      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"processes\">\n");

      dirp = opendir ("/proc");
      if (dirp)
	{
	  const int num_cores = sysconf (_SC_NPROCESSORS_ONLN);
	  struct dirent *dp;

	  while ((dp = readdir (dirp)) != NULL)
	    {
	      PID_T pid;
	      uid_t owner;
	      char user[UT_NAMESIZE];
	      char *command_line;
	      int *cores;
	      int task_count;
	      char *cores_str;
	      int i;

	      if (!isdigit (dp->d_name[0])
		  || NAMELEN (dp) > MAX_PID_T_STRLEN)
		continue;

	      sscanf (dp->d_name, "%lld", &pid);
	      command_line = commandline_from_pid (pid);

	      if (get_process_owner (&owner, pid) == 0)
		user_from_uid (user, sizeof (user), owner);
	      else
		strcpy (user, "?");

	      /* Find CPU cores used by the process.  */
	      cores = XCNEWVEC (int, num_cores);
	      task_count = get_cores_used_by_process (pid, cores, num_cores);
	      cores_str = (char *) xcalloc (task_count, sizeof ("4294967295") + 1);

	      for (i = 0; i < num_cores && task_count > 0; ++i)
		if (cores[i])
		  {
		    char core_str[sizeof ("4294967295")];

		    sprintf (core_str, "%d", i);
		    strcat (cores_str, core_str);

		    task_count -= cores[i];
		    if (task_count > 0)
		      strcat (cores_str, ",");
		  }

	      xfree (cores);
	      
	      buffer_xml_printf (
		  &buffer,
		  "<item>"
		  "<column name=\"pid\">%lld</column>"
		  "<column name=\"user\">%s</column>"
		  "<column name=\"command\">%s</column>"
		  "<column name=\"cores\">%s</column>"
		  "</item>",
		  pid,
		  user,
		  command_line ? command_line : "",
		  cores_str);

	      xfree (command_line);     
	      xfree (cores_str);
	    }
	  
	  closedir (dirp);
	}

      buffer_grow_str0 (&buffer, "</osdata>\n");
      buf = buffer_finish (&buffer);
      len_avail = strlen (buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, buf + offset, len);

  return len;
}

/* A simple PID/PGID pair.  */

struct pid_pgid_entry
{
  pid_pgid_entry (PID_T pid_, PID_T pgid_)
  : pid (pid_), pgid (pgid_)
  {}

  /* Return true if this pid is the leader of its process group.  */

  bool is_leader () const
  {
    return pid == pgid;
  }

  bool operator< (const pid_pgid_entry &other) const
  {
    /* Sort by PGID.  */
    if (this->pgid != other.pgid)
      return this->pgid < other.pgid;

    /* Process group leaders always come first...  */
    if (this->is_leader ())
      {
	if (!other.is_leader ())
	  return true;
      }
    else if (other.is_leader ())
      return false;

    /* ...else sort by PID.  */
    return this->pid < other.pid;
  }

  PID_T pid, pgid;
};

/* Collect all process groups from /proc.  */

static LONGEST
linux_xfer_osdata_processgroups (gdb_byte *readbuf,
				 ULONGEST offset, ULONGEST len)
{
  /* We make the process list snapshot when the object starts to be read.  */
  static const char *buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      DIR *dirp;

      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"process groups\">\n");

      dirp = opendir ("/proc");
      if (dirp)
	{
	  std::vector<pid_pgid_entry> process_list;
	  struct dirent *dp;

	  process_list.reserve (512);

	  /* Build list consisting of PIDs followed by their
	     associated PGID.  */
	  while ((dp = readdir (dirp)) != NULL)
	    {
	      PID_T pid, pgid;

	      if (!isdigit (dp->d_name[0])
		  || NAMELEN (dp) > MAX_PID_T_STRLEN)
		continue;

	      sscanf (dp->d_name, "%lld", &pid);
	      pgid = getpgid (pid);

	      if (pgid > 0)
		process_list.emplace_back (pid, pgid);
	    }

	  closedir (dirp);

	  /* Sort the process list.  */
	  std::sort (process_list.begin (), process_list.end ());

	  for (const pid_pgid_entry &entry : process_list)
	    {
	      PID_T pid = entry.pid;
	      PID_T pgid = entry.pgid;
	      char leader_command[32];
	      char *command_line;

	      command_from_pid (leader_command, sizeof (leader_command), pgid);
	      command_line = commandline_from_pid (pid);

	      buffer_xml_printf (
		  &buffer,
		  "<item>"
		  "<column name=\"pgid\">%lld</column>"
		  "<column name=\"leader command\">%s</column>"
		  "<column name=\"pid\">%lld</column>"
		  "<column name=\"command line\">%s</column>"
		  "</item>",
		  pgid,
		  leader_command,
		  pid,
		  command_line ? command_line : "");

	      xfree (command_line);
	    }
	}   

      buffer_grow_str0 (&buffer, "</osdata>\n");
      buf = buffer_finish (&buffer);
      len_avail = strlen (buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, buf + offset, len);

  return len;
}

/* Collect all the threads in /proc by iterating through processes and
   then tasks within each process.  */

static LONGEST
linux_xfer_osdata_threads (gdb_byte *readbuf,
			   ULONGEST offset, ULONGEST len)
{
  /* We make the process list snapshot when the object starts to be read.  */
  static const char *buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      DIR *dirp;

      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"threads\">\n");

      dirp = opendir ("/proc");
      if (dirp)
	{
	  struct dirent *dp;

	  while ((dp = readdir (dirp)) != NULL)
	    {
	      struct stat statbuf;
	      char procentry[sizeof ("/proc/4294967295")];

	      if (!isdigit (dp->d_name[0])
		  || NAMELEN (dp) > sizeof ("4294967295") - 1)
		continue;

	      xsnprintf (procentry, sizeof (procentry), "/proc/%s",
			 dp->d_name);
	      if (stat (procentry, &statbuf) == 0
		  && S_ISDIR (statbuf.st_mode))
		{
		  DIR *dirp2;
		  PID_T pid;
		  char command[32];

		  std::string pathname
		    = string_printf ("/proc/%s/task", dp->d_name);
		  
		  pid = atoi (dp->d_name);
		  command_from_pid (command, sizeof (command), pid);

		  dirp2 = opendir (pathname.c_str ());

		  if (dirp2)
		    {
		      struct dirent *dp2;

		      while ((dp2 = readdir (dirp2)) != NULL)
			{
			  PID_T tid;
			  int core;

			  if (!isdigit (dp2->d_name[0])
			      || NAMELEN (dp2) > sizeof ("4294967295") - 1)
			    continue;

			  tid = atoi (dp2->d_name);
			  core = linux_common_core_of_thread (ptid_t (pid, tid, 0));

			  buffer_xml_printf (
			    &buffer,
			    "<item>"
			    "<column name=\"pid\">%lld</column>"
			    "<column name=\"command\">%s</column>"
			    "<column name=\"tid\">%lld</column>"
			    "<column name=\"core\">%d</column>"
			    "</item>",
			    pid,
			    command,
			    tid,
			    core);
			}

		      closedir (dirp2);
		    }
		}
	    }

	  closedir (dirp);
	}

      buffer_grow_str0 (&buffer, "</osdata>\n");
      buf = buffer_finish (&buffer);
      len_avail = strlen (buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, buf + offset, len);

  return len;
}

/* Collect data about the cpus/cores on the system */

static LONGEST
linux_xfer_osdata_cpus (gdb_byte *readbuf,
			   ULONGEST offset, ULONGEST len)
{
  static const char *saved_buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      int first_item = 1;

      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      saved_buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"cpus\">\n");

      gdb_file_up fp = gdb_fopen_cloexec ("/proc/cpuinfo", "r");
      if (fp != NULL)
	{
	  char buf[8192];

	  do
	    {
	      if (fgets (buf, sizeof (buf), fp.get ()))
		{
		  char *key, *value;
		  int i = 0;

		  key = strtok (buf, ":");
		  if (key == NULL)
		    continue;

		  value = strtok (NULL, ":");
		  if (value == NULL)
		    continue;

		  while (key[i] != '\t' && key[i] != '\0')
		    i++;

		  key[i] = '\0';

		  i = 0;
		  while (value[i] != '\t' && value[i] != '\0')
		    i++;

		  value[i] = '\0';

		  if (strcmp (key, "processor") == 0)
		    {
		      if (first_item)
			buffer_grow_str (&buffer, "<item>");
		      else
			buffer_grow_str (&buffer, "</item><item>");

		      first_item = 0;
		    }

		  buffer_xml_printf (&buffer,
				     "<column name=\"%s\">%s</column>",
				     key,
				     value);
		}
	    }
	  while (!feof (fp.get ()));

	  if (first_item == 0)
	    buffer_grow_str (&buffer, "</item>");
	}

      buffer_grow_str0 (&buffer, "</osdata>\n");
      saved_buf = buffer_finish (&buffer);
      len_avail = strlen (saved_buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      saved_buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, saved_buf + offset, len);

  return len;
}

/* Collect all the open file descriptors found in /proc and put the details
   found about them into READBUF.  */

static LONGEST
linux_xfer_osdata_fds (gdb_byte *readbuf,
		       ULONGEST offset, ULONGEST len)
{
  /* We make the process list snapshot when the object starts to be read.  */
  static const char *saved_buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      DIR *dirp;

      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      saved_buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"files\">\n");

      dirp = opendir ("/proc");
      if (dirp)
	{
	  struct dirent *dp;

	  while ((dp = readdir (dirp)) != NULL)
	    {
	      struct stat statbuf;
	      char procentry[sizeof ("/proc/4294967295")];

	      if (!isdigit (dp->d_name[0])
		  || NAMELEN (dp) > sizeof ("4294967295") - 1)
		continue;

	      xsnprintf (procentry, sizeof (procentry), "/proc/%s",
			 dp->d_name);
	      if (stat (procentry, &statbuf) == 0
		  && S_ISDIR (statbuf.st_mode))
		{
		  DIR *dirp2;
		  PID_T pid;
		  char command[32];

		  pid = atoi (dp->d_name);
		  command_from_pid (command, sizeof (command), pid);

		  std::string pathname
		    = string_printf ("/proc/%s/fd", dp->d_name);
		  dirp2 = opendir (pathname.c_str ());

		  if (dirp2)
		    {
		      struct dirent *dp2;

		      while ((dp2 = readdir (dirp2)) != NULL)
			{
			  char buf[1000];
			  ssize_t rslt;

			  if (!isdigit (dp2->d_name[0]))
			    continue;

			  std::string fdname
			    = string_printf ("%s/%s", pathname.c_str (),
					     dp2->d_name);
			  rslt = readlink (fdname.c_str (), buf,
					   sizeof (buf) - 1);
			  if (rslt >= 0)
			    buf[rslt] = '\0';

			  buffer_xml_printf (
			    &buffer,
			    "<item>"
			    "<column name=\"pid\">%s</column>"
			    "<column name=\"command\">%s</column>"
			    "<column name=\"file descriptor\">%s</column>"
			    "<column name=\"name\">%s</column>"
			    "</item>",
			    dp->d_name,
			    command,
			    dp2->d_name,
			    (rslt >= 0 ? buf : dp2->d_name));
			}

		      closedir (dirp2);
		    }
		}
	    }

	  closedir (dirp);
	}

      buffer_grow_str0 (&buffer, "</osdata>\n");
      saved_buf = buffer_finish (&buffer);
      len_avail = strlen (saved_buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      saved_buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, saved_buf + offset, len);

  return len;
}

/* Returns the socket state STATE in textual form.  */

static const char *
format_socket_state (unsigned char state)
{
  /* Copied from include/net/tcp_states.h in the Linux kernel sources.  */
  enum {
    TCP_ESTABLISHED = 1,
    TCP_SYN_SENT,
    TCP_SYN_RECV,
    TCP_FIN_WAIT1,
    TCP_FIN_WAIT2,
    TCP_TIME_WAIT,
    TCP_CLOSE,
    TCP_CLOSE_WAIT,
    TCP_LAST_ACK,
    TCP_LISTEN,
    TCP_CLOSING
  };

  switch (state)
    {
    case TCP_ESTABLISHED:
      return "ESTABLISHED";
    case TCP_SYN_SENT:
      return "SYN_SENT";
    case TCP_SYN_RECV:
      return "SYN_RECV";
    case TCP_FIN_WAIT1:
      return "FIN_WAIT1";
    case TCP_FIN_WAIT2:
      return "FIN_WAIT2";
    case TCP_TIME_WAIT:
      return "TIME_WAIT";
    case TCP_CLOSE:
      return "CLOSE";
    case TCP_CLOSE_WAIT:
      return "CLOSE_WAIT";
    case TCP_LAST_ACK:
      return "LAST_ACK";
    case TCP_LISTEN:
      return "LISTEN";
    case TCP_CLOSING:
      return "CLOSING";
    default:
      return "(unknown)";
    }
}

union socket_addr
  {
    struct sockaddr sa;
    struct sockaddr_in sin;
    struct sockaddr_in6 sin6;
  };

/* Auxiliary function used by linux_xfer_osdata_isocket.  Formats
   information for all open internet sockets of type FAMILY on the
   system into BUFFER.  If TCP is set, only TCP sockets are processed,
   otherwise only UDP sockets are processed.  */

static void
print_sockets (unsigned short family, int tcp, struct buffer *buffer)
{
  const char *proc_file;

  if (family == AF_INET)
    proc_file = tcp ? "/proc/net/tcp" : "/proc/net/udp";
  else if (family == AF_INET6)
    proc_file = tcp ? "/proc/net/tcp6" : "/proc/net/udp6";
  else
    return;

  gdb_file_up fp = gdb_fopen_cloexec (proc_file, "r");
  if (fp)
    {
      char buf[8192];

      do
	{
	  if (fgets (buf, sizeof (buf), fp.get ()))
	    {
	      uid_t uid;
	      unsigned int local_port, remote_port, state;
	      char local_address[NI_MAXHOST], remote_address[NI_MAXHOST];
	      int result;

#if NI_MAXHOST <= 32
#error "local_address and remote_address buffers too small"
#endif

	      result = sscanf (buf,
			       "%*d: %32[0-9A-F]:%X %32[0-9A-F]:%X %X %*X:%*X %*X:%*X %*X %d %*d %*u %*s\n",
			       local_address, &local_port,
			       remote_address, &remote_port,
			       &state,
			       &uid);
	      
	      if (result == 6)
		{
		  union socket_addr locaddr, remaddr;
		  size_t addr_size;
		  char user[UT_NAMESIZE];
		  char local_service[NI_MAXSERV], remote_service[NI_MAXSERV];

		  if (family == AF_INET)
		    {
		      sscanf (local_address, "%X",
			      &locaddr.sin.sin_addr.s_addr);
		      sscanf (remote_address, "%X",
			      &remaddr.sin.sin_addr.s_addr);
		      
		      locaddr.sin.sin_port = htons (local_port);
		      remaddr.sin.sin_port = htons (remote_port);

		      addr_size = sizeof (struct sockaddr_in);
		    }
		  else
		    {
		      sscanf (local_address, "%8X%8X%8X%8X",
			      locaddr.sin6.sin6_addr.s6_addr32,
			      locaddr.sin6.sin6_addr.s6_addr32 + 1,
			      locaddr.sin6.sin6_addr.s6_addr32 + 2,
			      locaddr.sin6.sin6_addr.s6_addr32 + 3);
		      sscanf (remote_address, "%8X%8X%8X%8X",
			      remaddr.sin6.sin6_addr.s6_addr32,
			      remaddr.sin6.sin6_addr.s6_addr32 + 1,
			      remaddr.sin6.sin6_addr.s6_addr32 + 2,
			      remaddr.sin6.sin6_addr.s6_addr32 + 3);

		      locaddr.sin6.sin6_port = htons (local_port);
		      remaddr.sin6.sin6_port = htons (remote_port);
		      
		      locaddr.sin6.sin6_flowinfo = 0;
		      remaddr.sin6.sin6_flowinfo = 0;
		      locaddr.sin6.sin6_scope_id = 0;
		      remaddr.sin6.sin6_scope_id = 0;

		      addr_size = sizeof (struct sockaddr_in6);
		    }
	      
		  locaddr.sa.sa_family = remaddr.sa.sa_family = family;
		      
		  result = getnameinfo (&locaddr.sa, addr_size,
					local_address, sizeof (local_address),
					local_service, sizeof (local_service),
					NI_NUMERICHOST | NI_NUMERICSERV
					| (tcp ? 0 : NI_DGRAM));
		  if (result)
		    continue;
		  
		  result = getnameinfo (&remaddr.sa, addr_size,
					remote_address,
					sizeof (remote_address),
					remote_service,
					sizeof (remote_service),
					NI_NUMERICHOST | NI_NUMERICSERV
					| (tcp ? 0 : NI_DGRAM));
		  if (result)
		    continue;
		  
		  user_from_uid (user, sizeof (user), uid);
		  
		  buffer_xml_printf (
		      buffer,
		      "<item>"
		      "<column name=\"local address\">%s</column>"
		      "<column name=\"local port\">%s</column>"
		      "<column name=\"remote address\">%s</column>"
		      "<column name=\"remote port\">%s</column>"
		      "<column name=\"state\">%s</column>"
		      "<column name=\"user\">%s</column>"
		      "<column name=\"family\">%s</column>" 
		      "<column name=\"protocol\">%s</column>"
		      "</item>",
		      local_address,
		      local_service,
		      remote_address,
		      remote_service,
		      format_socket_state (state),
		      user,
		      (family == AF_INET) ? "INET" : "INET6",
		      tcp ? "STREAM" : "DGRAM");
		}
	    }
	}
      while (!feof (fp.get ()));
    }
}

/* Collect data about internet sockets and write it into READBUF.  */

static LONGEST
linux_xfer_osdata_isockets (gdb_byte *readbuf,
			    ULONGEST offset, ULONGEST len)
{
  static const char *buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"I sockets\">\n");

      print_sockets (AF_INET, 1, &buffer);
      print_sockets (AF_INET, 0, &buffer);
      print_sockets (AF_INET6, 1, &buffer);
      print_sockets (AF_INET6, 0, &buffer);

      buffer_grow_str0 (&buffer, "</osdata>\n");
      buf = buffer_finish (&buffer);
      len_avail = strlen (buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, buf + offset, len);

  return len;
}

/* Converts the time SECONDS into textual form and copies it into a
   buffer TIME, with at most MAXLEN characters copied.  */

static void
time_from_time_t (char *time, int maxlen, TIME_T seconds)
{
  if (!seconds)
    time[0] = '\0';
  else
    {
      time_t t = (time_t) seconds;
      
      strncpy (time, ctime (&t), maxlen);
      time[maxlen - 1] = '\0';
    }
}

/* Finds the group name for the group GID and copies it into GROUP.
   At most MAXLEN characters are copied.  */

static void
group_from_gid (char *group, int maxlen, gid_t gid)
{
  struct group *grentry = getgrgid (gid);
  
  if (grentry)
    {
      strncpy (group, grentry->gr_name, maxlen);
      /* Ensure that the group name is null-terminated.  */
      group[maxlen - 1] = '\0';
    }
  else
    group[0] = '\0';
}

/* Collect data about shared memory recorded in /proc and write it
   into READBUF.  */

static LONGEST
linux_xfer_osdata_shm (gdb_byte *readbuf,
		       ULONGEST offset, ULONGEST len)
{
  static const char *saved_buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      saved_buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"shared memory\">\n");

      gdb_file_up fp = gdb_fopen_cloexec ("/proc/sysvipc/shm", "r");
      if (fp)
	{
	  char buf[8192];

	  do
	    {
	      if (fgets (buf, sizeof (buf), fp.get ()))
		{
		  key_t key;
		  uid_t uid, cuid;
		  gid_t gid, cgid;
		  PID_T cpid, lpid;
		  int shmid, size, nattch;
		  TIME_T atime, dtime, ctime;
		  unsigned int perms;
		  int items_read;
				  
		  items_read = sscanf (buf,
				       "%d %d %o %d %lld %lld %d %u %u %u %u %lld %lld %lld",
				       &key, &shmid, &perms, &size,
				       &cpid, &lpid,
				       &nattch,
				       &uid, &gid, &cuid, &cgid,
				       &atime, &dtime, &ctime);

		  if (items_read == 14)
		    {
		      char user[UT_NAMESIZE], group[UT_NAMESIZE];
		      char cuser[UT_NAMESIZE], cgroup[UT_NAMESIZE];
		      char ccmd[32], lcmd[32];
		      char atime_str[32], dtime_str[32], ctime_str[32];
		      
		      user_from_uid (user, sizeof (user), uid);
		      group_from_gid (group, sizeof (group), gid);
		      user_from_uid (cuser, sizeof (cuser), cuid);
		      group_from_gid (cgroup, sizeof (cgroup), cgid);
		      
		      command_from_pid (ccmd, sizeof (ccmd), cpid);
		      command_from_pid (lcmd, sizeof (lcmd), lpid);
		      
		      time_from_time_t (atime_str, sizeof (atime_str), atime);
		      time_from_time_t (dtime_str, sizeof (dtime_str), dtime);
		      time_from_time_t (ctime_str, sizeof (ctime_str), ctime);
		      
		      buffer_xml_printf (
		          &buffer,
			  "<item>"
			  "<column name=\"key\">%d</column>"
			  "<column name=\"shmid\">%d</column>"
			  "<column name=\"permissions\">%o</column>"
			  "<column name=\"size\">%d</column>"
			  "<column name=\"creator command\">%s</column>"
			  "<column name=\"last op. command\">%s</column>"
			  "<column name=\"num attached\">%d</column>"
			  "<column name=\"user\">%s</column>"
			  "<column name=\"group\">%s</column>"
			  "<column name=\"creator user\">%s</column>"
			  "<column name=\"creator group\">%s</column>"
			  "<column name=\"last shmat() time\">%s</column>"
			  "<column name=\"last shmdt() time\">%s</column>"
			  "<column name=\"last shmctl() time\">%s</column>"
			  "</item>",
			  key,
			  shmid,
			  perms,
			  size,
			  ccmd,
			  lcmd,
			  nattch,
			  user,
			  group,
			  cuser,
			  cgroup,
			  atime_str,
			  dtime_str,
			  ctime_str);
		    }
		}
	    }
	  while (!feof (fp.get ()));
	}
      
      buffer_grow_str0 (&buffer, "</osdata>\n");
      saved_buf = buffer_finish (&buffer);
      len_avail = strlen (saved_buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      saved_buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, saved_buf + offset, len);

  return len;
}

/* Collect data about semaphores recorded in /proc and write it
   into READBUF.  */

static LONGEST
linux_xfer_osdata_sem (gdb_byte *readbuf,
		       ULONGEST offset, ULONGEST len)
{
  static const char *saved_buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      saved_buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"semaphores\">\n");

      gdb_file_up fp = gdb_fopen_cloexec ("/proc/sysvipc/sem", "r");
      if (fp)
	{
	  char buf[8192];
	  
	  do
	    {
	      if (fgets (buf, sizeof (buf), fp.get ()))
		{
		  key_t key;
		  uid_t uid, cuid;
		  gid_t gid, cgid;
		  unsigned int perms, nsems;
		  int semid;
		  TIME_T otime, ctime;
		  int items_read;
		  
		  items_read = sscanf (buf,
				       "%d %d %o %u %d %d %d %d %lld %lld",
				       &key, &semid, &perms, &nsems,
				       &uid, &gid, &cuid, &cgid,
				       &otime, &ctime);
		  
		  if (items_read == 10)
		    {
		      char user[UT_NAMESIZE], group[UT_NAMESIZE];
		      char cuser[UT_NAMESIZE], cgroup[UT_NAMESIZE];
		      char otime_str[32], ctime_str[32];
		      
		      user_from_uid (user, sizeof (user), uid);
		      group_from_gid (group, sizeof (group), gid);
		      user_from_uid (cuser, sizeof (cuser), cuid);
		      group_from_gid (cgroup, sizeof (cgroup), cgid);
		      
		      time_from_time_t (otime_str, sizeof (otime_str), otime);
		      time_from_time_t (ctime_str, sizeof (ctime_str), ctime);
		      
		      buffer_xml_printf (
			  &buffer,
			  "<item>"
			  "<column name=\"key\">%d</column>"
			  "<column name=\"semid\">%d</column>"
			  "<column name=\"permissions\">%o</column>"
			  "<column name=\"num semaphores\">%u</column>"
			  "<column name=\"user\">%s</column>"
			  "<column name=\"group\">%s</column>"
			  "<column name=\"creator user\">%s</column>"
			  "<column name=\"creator group\">%s</column>"
			  "<column name=\"last semop() time\">%s</column>"
			  "<column name=\"last semctl() time\">%s</column>"
			  "</item>",
			  key,
			  semid,
			  perms,
			  nsems,
			  user,
			  group,
			  cuser,
			  cgroup,
			  otime_str,
			  ctime_str);
		    }
		}
	    }
	  while (!feof (fp.get ()));
	}

      buffer_grow_str0 (&buffer, "</osdata>\n");
      saved_buf = buffer_finish (&buffer);
      len_avail = strlen (saved_buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      saved_buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, saved_buf + offset, len);

  return len;
}

/* Collect data about message queues recorded in /proc and write it
   into READBUF.  */

static LONGEST
linux_xfer_osdata_msg (gdb_byte *readbuf,
		       ULONGEST offset, ULONGEST len)
{
  static const char *saved_buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      saved_buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"message queues\">\n");
      
      gdb_file_up fp = gdb_fopen_cloexec ("/proc/sysvipc/msg", "r");
      if (fp)
	{
	  char buf[8192];
	  
	  do
	    {
	      if (fgets (buf, sizeof (buf), fp.get ()))
		{
		  key_t key;
		  PID_T lspid, lrpid;
		  uid_t uid, cuid;
		  gid_t gid, cgid;
		  unsigned int perms, cbytes, qnum;
		  int msqid;
		  TIME_T stime, rtime, ctime;
		  int items_read;
		  
		  items_read = sscanf (buf,
				       "%d %d %o %u %u %lld %lld %d %d %d %d %lld %lld %lld",
				       &key, &msqid, &perms, &cbytes, &qnum,
				       &lspid, &lrpid, &uid, &gid, &cuid, &cgid,
				       &stime, &rtime, &ctime);
		  
		  if (items_read == 14)
		    {
		      char user[UT_NAMESIZE], group[UT_NAMESIZE];
		      char cuser[UT_NAMESIZE], cgroup[UT_NAMESIZE];
		      char lscmd[32], lrcmd[32];
		      char stime_str[32], rtime_str[32], ctime_str[32];
		      
		      user_from_uid (user, sizeof (user), uid);
		      group_from_gid (group, sizeof (group), gid);
		      user_from_uid (cuser, sizeof (cuser), cuid);
		      group_from_gid (cgroup, sizeof (cgroup), cgid);
		      
		      command_from_pid (lscmd, sizeof (lscmd), lspid);
		      command_from_pid (lrcmd, sizeof (lrcmd), lrpid);
		      
		      time_from_time_t (stime_str, sizeof (stime_str), stime);
		      time_from_time_t (rtime_str, sizeof (rtime_str), rtime);
		      time_from_time_t (ctime_str, sizeof (ctime_str), ctime);
		      
		      buffer_xml_printf (
			  &buffer,
			  "<item>"
			  "<column name=\"key\">%d</column>"
			  "<column name=\"msqid\">%d</column>"
			  "<column name=\"permissions\">%o</column>"
			  "<column name=\"num used bytes\">%u</column>"
			  "<column name=\"num messages\">%u</column>"
			  "<column name=\"last msgsnd() command\">%s</column>"
			  "<column name=\"last msgrcv() command\">%s</column>"
			  "<column name=\"user\">%s</column>"
			  "<column name=\"group\">%s</column>"
			  "<column name=\"creator user\">%s</column>"
			  "<column name=\"creator group\">%s</column>"
			  "<column name=\"last msgsnd() time\">%s</column>"
			  "<column name=\"last msgrcv() time\">%s</column>"
			  "<column name=\"last msgctl() time\">%s</column>"
			  "</item>",
			  key,
			  msqid,
			  perms,
			  cbytes,
			  qnum,
			  lscmd,
			  lrcmd,
			  user,
			  group,
			  cuser,
			  cgroup,
			  stime_str,
			  rtime_str,
			  ctime_str);
		    }
		}
	    }
	  while (!feof (fp.get ()));
	}

      buffer_grow_str0 (&buffer, "</osdata>\n");
      saved_buf = buffer_finish (&buffer);
      len_avail = strlen (saved_buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      saved_buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, saved_buf + offset, len);

  return len;
}

/* Collect data about loaded kernel modules and write it into
   READBUF.  */

static LONGEST
linux_xfer_osdata_modules (gdb_byte *readbuf,
			   ULONGEST offset, ULONGEST len)
{
  static const char *saved_buf;
  static LONGEST len_avail = -1;
  static struct buffer buffer;

  if (offset == 0)
    {
      if (len_avail != -1 && len_avail != 0)
	buffer_free (&buffer);
      len_avail = 0;
      saved_buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"modules\">\n");

      gdb_file_up fp = gdb_fopen_cloexec ("/proc/modules", "r");
      if (fp)
	{
	  char buf[8192];
	  
	  do
	    {
	      if (fgets (buf, sizeof (buf), fp.get ()))
		{
		  char *name, *dependencies, *status, *tmp;
		  unsigned int size;
		  unsigned long long address;
		  int uses;

		  name = strtok (buf, " ");
		  if (name == NULL)
		    continue;

		  tmp = strtok (NULL, " ");
		  if (tmp == NULL)
		    continue;
		  if (sscanf (tmp, "%u", &size) != 1)
		    continue;

		  tmp = strtok (NULL, " ");
		  if (tmp == NULL)
		    continue;
		  if (sscanf (tmp, "%d", &uses) != 1)
		    continue;

		  dependencies = strtok (NULL, " ");
		  if (dependencies == NULL)
		    continue;

		  status = strtok (NULL, " ");
		  if (status == NULL)
		    continue;

		  tmp = strtok (NULL, "\n");
		  if (tmp == NULL)
		    continue;
		  if (sscanf (tmp, "%llx", &address) != 1)
		    continue;

		  buffer_xml_printf (
			&buffer,
			"<item>"
			"<column name=\"name\">%s</column>"
			"<column name=\"size\">%u</column>"
			"<column name=\"num uses\">%d</column>"
			"<column name=\"dependencies\">%s</column>"
			"<column name=\"status\">%s</column>"
			"<column name=\"address\">%llx</column>"
			"</item>",
			name,
			size,
			uses,
			dependencies,
			status,
			address);
		}
	    }
	  while (!feof (fp.get ()));
	}

      buffer_grow_str0 (&buffer, "</osdata>\n");
      saved_buf = buffer_finish (&buffer);
      len_avail = strlen (saved_buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the buffer.  */
      buffer_free (&buffer);
      saved_buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, saved_buf + offset, len);

  return len;
}

struct osdata_type {
  const char *type;
  const char *title;
  const char *description;
  LONGEST (*getter) (gdb_byte *readbuf, ULONGEST offset, ULONGEST len);
} osdata_table[] = {
  { "cpus", "CPUs", "Listing of all cpus/cores on the system",
    linux_xfer_osdata_cpus },
  { "files", "File descriptors", "Listing of all file descriptors",
    linux_xfer_osdata_fds },
  { "modules", "Kernel modules", "Listing of all loaded kernel modules",
    linux_xfer_osdata_modules },
  { "msg", "Message queues", "Listing of all message queues",
    linux_xfer_osdata_msg },
  { "processes", "Processes", "Listing of all processes",
    linux_xfer_osdata_processes },
  { "procgroups", "Process groups", "Listing of all process groups",
    linux_xfer_osdata_processgroups },
  { "semaphores", "Semaphores", "Listing of all semaphores",
    linux_xfer_osdata_sem },
  { "shm", "Shared-memory regions", "Listing of all shared-memory regions",
    linux_xfer_osdata_shm },
  { "sockets", "Sockets", "Listing of all internet-domain sockets",
    linux_xfer_osdata_isockets },
  { "threads", "Threads", "Listing of all threads",
    linux_xfer_osdata_threads },
  { NULL, NULL, NULL }
};

LONGEST
linux_common_xfer_osdata (const char *annex, gdb_byte *readbuf,
			  ULONGEST offset, ULONGEST len)
{
  if (!annex || *annex == '\0')
    {
      static const char *buf;
      static LONGEST len_avail = -1;
      static struct buffer buffer;

      if (offset == 0)
	{
	  int i;

	  if (len_avail != -1 && len_avail != 0)
	    buffer_free (&buffer);
	  len_avail = 0;
	  buf = NULL;
	  buffer_init (&buffer);
	  buffer_grow_str (&buffer, "<osdata type=\"types\">\n");

	  for (i = 0; osdata_table[i].type; ++i)
	    buffer_xml_printf (
			       &buffer,
			       "<item>"
			       "<column name=\"Type\">%s</column>"
			       "<column name=\"Description\">%s</column>"
			       "<column name=\"Title\">%s</column>"
			       "</item>",
			       osdata_table[i].type,
			       osdata_table[i].description,
			       osdata_table[i].title);

	  buffer_grow_str0 (&buffer, "</osdata>\n");
	  buf = buffer_finish (&buffer);
	  len_avail = strlen (buf);
	}

      if (offset >= len_avail)
	{
	  /* Done.  Get rid of the buffer.  */
	  buffer_free (&buffer);
	  buf = NULL;
	  len_avail = 0;
	  return 0;
	}

      if (len > len_avail - offset)
	len = len_avail - offset;
      memcpy (readbuf, buf + offset, len);

      return len;
    }
  else
    {
      int i;

      for (i = 0; osdata_table[i].type; ++i)
	{
	  if (strcmp (annex, osdata_table[i].type) == 0)
	    {
	      gdb_assert (readbuf);
	      
	      return (osdata_table[i].getter) (readbuf, offset, len);
	    }
	}

      return 0;
    }
}