linux-osdata.c

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/* 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_get_pid (ptid), (PID_T) ptid_get_lwp (ptid));
  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)
{
  char *stat_path = xstrprintf ("/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.  */
    
  xfree (stat_path);
}

/* 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)
{
  char *pathname = xstrprintf ("/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, "]");
    }
    }

  xfree (pathname);

  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_build ((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 ())
      return true;

    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;
          char *pathname;
          PID_T pid;
          char command[32];

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

          dirp2 = opendir (pathname);

          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_build (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);
            }

          xfree (pathname);
        }
        }

      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 *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;
      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");
      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 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 *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=\"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))
        {
          char *pathname;
          DIR *dirp2;
          PID_T pid;
          char command[32];

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

          pathname = xstrprintf ("/proc/%s/fd", dp->d_name);
          dirp2 = opendir (pathname);

          if (dirp2)
            {
              struct dirent *dp2;

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

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

              fdname = xstrprintf ("%s/%s", pathname, dp2->d_name);
              rslt = readlink (fdname, 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);
            }

          xfree (pathname);
        }
        }

      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;
}

/* 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 *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=\"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");
      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 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 *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=\"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");
      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 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 *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=\"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");
      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 loaded kernel modules and write it into
   READBUF.  */

static LONGEST
linux_xfer_osdata_modules (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=\"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");
      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;
}

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;
    }
}