/* Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Thorsten Kukuk <kukuk@vt.uni-paderborn.de>, 1996.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <ctype.h>

#include <errno.h>

#include <fcntl.h>

#include <netdb.h>

#include <nss.h>

#include <nsswitch.h>

#include <shadow.h>

#include <stdio_ext.h>

#include <string.h>

#include <libc-lock.h>

#include <kernel-features.h>

#include "netgroup.h"

#include "nisdomain.h"

static service_user *ni;

static enum nss_status (*nss_setspent) (int stayopen);

static enum nss_status (*nss_getspnam_r) (const char *name, struct spwd * sp,

					  char *buffer, size_t buflen,

					  int *errnop);

static enum nss_status (*nss_getspent_r) (struct spwd * sp, char *buffer,

					  size_t buflen, int *errnop);

static enum nss_status (*nss_endspent) (void);

/* Get the declaration of the parser function.  */

#define ENTNAME spent

#define STRUCTURE spwd

#define EXTERN_PARSER

#include <nss/nss_files/files-parse.c>

/* Structure for remembering -@netgroup and -user members ... */

#define BLACKLIST_INITIAL_SIZE 512

#define BLACKLIST_INCREMENT 256

struct blacklist_t

{

  char *data;

  int current;

  int size;

};

struct ent_t

{

  bool netgroup;

  bool files;

  bool first;

  enum nss_status setent_status;

  FILE *stream;

  struct blacklist_t blacklist;

  struct spwd pwd;

  struct __netgrent netgrdata;

};

typedef struct ent_t ent_t;

static ent_t ext_ent = { false, true, false, NSS_STATUS_SUCCESS, NULL,

			 { NULL, 0, 0},

			 { NULL, NULL, 0, 0, 0, 0, 0, 0, 0}};

/* Protect global state against multiple changers.  */

__libc_lock_define_initialized (static, lock)

/* Prototypes for local functions.  */

static void blacklist_store_name (const char *, ent_t *);

static bool in_blacklist (const char *, int, ent_t *);

/* Initialize the NSS interface/functions. The calling function must

   hold the lock.  */

static void

init_nss_interface (void)

{

  if (__nss_database_lookup ("shadow_compat", "passwd_compat",

			     "nis", &ni) >= 0)

    {

      nss_setspent = __nss_lookup_function (ni, "setspent");

      nss_getspnam_r = __nss_lookup_function (ni, "getspnam_r");

      nss_getspent_r = __nss_lookup_function (ni, "getspent_r");

      nss_endspent = __nss_lookup_function (ni, "endspent");

    }

}

static void

give_spwd_free (struct spwd *pwd)

{

  free (pwd->sp_namp);

  free (pwd->sp_pwdp);

  memset (pwd, '\0', sizeof (struct spwd));

  pwd->sp_warn = -1;

  pwd->sp_inact = -1;

  pwd->sp_expire = -1;

  pwd->sp_flag = ~0ul;

}

static int

spwd_need_buflen (struct spwd *pwd)

{

  int len = 0;

  if (pwd->sp_pwdp != NULL)

    len += strlen (pwd->sp_pwdp) + 1;

  return len;

}

static void

copy_spwd_changes (struct spwd *dest, struct spwd *src,

		   char *buffer, size_t buflen)

{

  if (src->sp_pwdp != NULL && strlen (src->sp_pwdp))

    {

      if (buffer == NULL)

	dest->sp_pwdp = strdup (src->sp_pwdp);

      else if (dest->sp_pwdp &&

	       strlen (dest->sp_pwdp) >= strlen (src->sp_pwdp))

	strcpy (dest->sp_pwdp, src->sp_pwdp);

      else

	{

	  dest->sp_pwdp = buffer;

	  strcpy (dest->sp_pwdp, src->sp_pwdp);

	  buffer += strlen (dest->sp_pwdp) + 1;

	  buflen = buflen - (strlen (dest->sp_pwdp) + 1);

	}

    }

  if (src->sp_lstchg != 0)

    dest->sp_lstchg = src->sp_lstchg;

  if (src->sp_min != 0)

    dest->sp_min = src->sp_min;

  if (src->sp_max != 0)

    dest->sp_max = src->sp_max;

  if (src->sp_warn != -1)

    dest->sp_warn = src->sp_warn;

  if (src->sp_inact != -1)

    dest->sp_inact = src->sp_inact;

  if (src->sp_expire != -1)

    dest->sp_expire = src->sp_expire;

  if (src->sp_flag != ~0ul)

    dest->sp_flag = src->sp_flag;

}

static enum nss_status

internal_setspent (ent_t *ent, int stayopen, int needent)

{

  enum nss_status status = NSS_STATUS_SUCCESS;

  ent->first = ent->netgroup = 0;

  ent->files = true;

  /* If something was left over free it.  */

  if (ent->netgroup)

    __internal_endnetgrent (&ent->netgrdata);

  if (ent->blacklist.data != NULL)

    {

      ent->blacklist.current = 1;

      ent->blacklist.data[0] = '|';

      ent->blacklist.data[1] = '\0';

    }

  else

    ent->blacklist.current = 0;

  if (ent->stream == NULL)

    {

      ent->stream = fopen ("/etc/shadow", "rme");

      if (ent->stream == NULL)

	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;

      else

	/* We take care of locking ourself.  */

	__fsetlocking (ent->stream, FSETLOCKING_BYCALLER);

    }

  else

    rewind (ent->stream);

  give_spwd_free (&ent->pwd);

  if (needent && status == NSS_STATUS_SUCCESS && nss_setspent)

    ent->setent_status = nss_setspent (stayopen);

  return status;

}

enum nss_status

_nss_compat_setspent (int stayopen)

{

  enum nss_status result;

  __libc_lock_lock (lock);

  if (ni == NULL)

    init_nss_interface ();

  result = internal_setspent (&ext_ent, stayopen, 1);

  __libc_lock_unlock (lock);

  return result;

}

static enum nss_status

internal_endspent (ent_t *ent)

{

  if (ent->stream != NULL)

    {

      fclose (ent->stream);

      ent->stream = NULL;

    }

  if (ent->netgroup)

    __internal_endnetgrent (&ent->netgrdata);

  ent->first = ent->netgroup = false;

  ent->files = true;

  if (ent->blacklist.data != NULL)

    {

      ent->blacklist.current = 1;

      ent->blacklist.data[0] = '|';

      ent->blacklist.data[1] = '\0';

    }

  else

    ent->blacklist.current = 0;

  give_spwd_free (&ent->pwd);

  return NSS_STATUS_SUCCESS;

}

enum nss_status

_nss_compat_endspent (void)

{

  enum nss_status result;

  __libc_lock_lock (lock);

  if (nss_endspent)

    nss_endspent ();

  result = internal_endspent (&ext_ent);

  __libc_lock_unlock (lock);

  return result;

}

static enum nss_status

getspent_next_nss_netgr (const char *name, struct spwd *result, ent_t *ent,

			 char *group, char *buffer, size_t buflen,

			 int *errnop)

{

  char *curdomain = NULL, *host, *user, *domain, *p2;

  size_t p2len;

  if (!nss_getspnam_r)

    return NSS_STATUS_UNAVAIL;

  /* If the setpwent call failed, say so.  */

  if (ent->setent_status != NSS_STATUS_SUCCESS)

    return ent->setent_status;

  if (ent->first)

    {

      memset (&ent->netgrdata, 0, sizeof (struct __netgrent));

      __internal_setnetgrent (group, &ent->netgrdata);

      ent->first = false;

    }

  while (1)

    {

      enum nss_status status;

      status = __internal_getnetgrent_r (&host, &user, &domain,

					 &ent->netgrdata, buffer, buflen,

					 errnop);

      if (status != 1)

	{

	  __internal_endnetgrent (&ent->netgrdata);

	  ent->netgroup = false;

	  give_spwd_free (&ent->pwd);

	  return NSS_STATUS_RETURN;

	}

      if (user == NULL || user[0] == '-')

	continue;

      if (domain != NULL)

	{

	  if (curdomain == NULL

	      && __nss_get_default_domain (&curdomain) != 0)

	    {

	      __internal_endnetgrent (&ent->netgrdata);

	      ent->netgroup = false;

	      give_spwd_free (&ent->pwd);

	      return NSS_STATUS_UNAVAIL;

	    }

	  if (strcmp (curdomain, domain) != 0)

	    continue;

	}

      /* If name != NULL, we are called from getpwnam */

      if (name != NULL)

	if (strcmp (user, name) != 0)

	  continue;

      p2len = spwd_need_buflen (&ent->pwd);

      if (p2len > buflen)

	{

	  *errnop = ERANGE;

	  return NSS_STATUS_TRYAGAIN;

	}

      p2 = buffer + (buflen - p2len);

      buflen -= p2len;

      if (nss_getspnam_r (user, result, buffer, buflen, errnop) !=

	  NSS_STATUS_SUCCESS)

	continue;

      if (!in_blacklist (result->sp_namp, strlen (result->sp_namp), ent))

	{

	  /* Store the User in the blacklist for possible the "+" at the

	     end of /etc/passwd */

	  blacklist_store_name (result->sp_namp, ent);

	  copy_spwd_changes (result, &ent->pwd, p2, p2len);

	  break;

	}

    }

  return NSS_STATUS_SUCCESS;

}

static enum nss_status

getspent_next_nss (struct spwd *result, ent_t *ent,

		   char *buffer, size_t buflen, int *errnop)

{

  enum nss_status status;

  char *p2;

  size_t p2len;

  if (!nss_getspent_r)

    return NSS_STATUS_UNAVAIL;

  p2len = spwd_need_buflen (&ent->pwd);

  if (p2len > buflen)

    {

      *errnop = ERANGE;

      return NSS_STATUS_TRYAGAIN;

    }

  p2 = buffer + (buflen - p2len);

  buflen -= p2len;

  do

    {

      if ((status = nss_getspent_r (result, buffer, buflen, errnop)) !=

	  NSS_STATUS_SUCCESS)

	return status;

    }

  while (in_blacklist (result->sp_namp, strlen (result->sp_namp), ent));

  copy_spwd_changes (result, &ent->pwd, p2, p2len);

  return NSS_STATUS_SUCCESS;

}

/* This function handle the +user entrys in /etc/shadow */

static enum nss_status

getspnam_plususer (const char *name, struct spwd *result, ent_t *ent,

		   char *buffer, size_t buflen, int *errnop)

{

  if (!nss_getspnam_r)

    return NSS_STATUS_UNAVAIL;

  struct spwd pwd;

  memset (&pwd, '\0', sizeof (struct spwd));

  pwd.sp_warn = -1;

  pwd.sp_inact = -1;

  pwd.sp_expire = -1;

  pwd.sp_flag = ~0ul;

  copy_spwd_changes (&pwd, result, NULL, 0);

  size_t plen = spwd_need_buflen (&pwd);

  if (plen > buflen)

    {

      *errnop = ERANGE;

      return NSS_STATUS_TRYAGAIN;

    }

  char *p = buffer + (buflen - plen);

  buflen -= plen;

  enum nss_status status = nss_getspnam_r (name, result, buffer, buflen,

					   errnop);

  if (status != NSS_STATUS_SUCCESS)

    return status;

  if (in_blacklist (result->sp_namp, strlen (result->sp_namp), ent))

    return NSS_STATUS_NOTFOUND;

  copy_spwd_changes (result, &pwd, p, plen);

  give_spwd_free (&pwd);

  /* We found the entry.  */

  return NSS_STATUS_SUCCESS;

}

static enum nss_status

getspent_next_file (struct spwd *result, ent_t *ent,

		    char *buffer, size_t buflen, int *errnop)

{

  struct parser_data *data = (void *) buffer;

  while (1)

    {

      fpos_t pos;

      int parse_res = 0;

      char *p;

      do

	{

	  /* We need at least 3 characters for one line.  */

	  if (__glibc_unlikely (buflen < 3))

	    {

	    erange:

	      *errnop = ERANGE;

	      return NSS_STATUS_TRYAGAIN;

	    }

	  fgetpos (ent->stream, &pos;;

	  buffer[buflen - 1] = '\xff';

	  p = fgets_unlocked (buffer, buflen, ent->stream);

	  if (p == NULL && feof_unlocked (ent->stream))

	    return NSS_STATUS_NOTFOUND;

	  if (p == NULL || __builtin_expect (buffer[buflen - 1] != '\xff', 0))

	    {

	    erange_reset:

	      fsetpos (ent->stream, &pos;;

	      goto erange;

	    }

	  /* Skip leading blanks.  */

	  while (isspace (*p))

	    ++p;

	}

      while (*p == '\0' || *p == '#'	/* Ignore empty and comment lines.  */

	     /* Parse the line.  If it is invalid, loop to

	        get the next line of the file to parse.  */

	     || !(parse_res = _nss_files_parse_spent (p, result, data,

						      buflen, errnop)));

      if (__glibc_unlikely (parse_res == -1))

	/* The parser ran out of space.  */

	goto erange_reset;

      if (result->sp_namp[0] != '+' && result->sp_namp[0] != '-')

	/* This is a real entry.  */

	break;

      /* -@netgroup */

      if (result->sp_namp[0] == '-' && result->sp_namp[1] == '@'

	  && result->sp_namp[2] != '\0')

	{

	  /* XXX Do not use fixed length buffers.  */

	  char buf2[1024];

	  char *user, *host, *domain;

	  struct __netgrent netgrdata;

	  memset (&netgrdata, 0, sizeof (struct __netgrent));

	  __internal_setnetgrent (&result->sp_namp[2], &netgrdata);

	  while (__internal_getnetgrent_r (&host, &user, &domain,

					   &netgrdata, buf2, sizeof (buf2),

					   errnop))

	    {

	      if (user != NULL && user[0] != '-')

		blacklist_store_name (user, ent);

	    }

	  __internal_endnetgrent (&netgrdata);

	  continue;

	}

      /* +@netgroup */

      if (result->sp_namp[0] == '+' && result->sp_namp[1] == '@'

	  && result->sp_namp[2] != '\0')

	{

	  int status;

	  ent->netgroup = true;

	  ent->first = true;

	  copy_spwd_changes (&ent->pwd, result, NULL, 0);

	  status = getspent_next_nss_netgr (NULL, result, ent,

					    &result->sp_namp[2],

					    buffer, buflen, errnop);

	  if (status == NSS_STATUS_RETURN)

	    continue;

	  else

	    return status;

	}

      /* -user */

      if (result->sp_namp[0] == '-' && result->sp_namp[1] != '\0'

	  && result->sp_namp[1] != '@')

	{

	  blacklist_store_name (&result->sp_namp[1], ent);

	  continue;

	}

      /* +user */

      if (result->sp_namp[0] == '+' && result->sp_namp[1] != '\0'

	  && result->sp_namp[1] != '@')

	{

	  size_t len = strlen (result->sp_namp);

	  char buf[len];

	  enum nss_status status;

	  /* Store the User in the blacklist for the "+" at the end of

	     /etc/passwd */

	  memcpy (buf, &result->sp_namp[1], len);

	  status = getspnam_plususer (&result->sp_namp[1], result, ent,

				      buffer, buflen, errnop);

	  blacklist_store_name (buf, ent);

	  if (status == NSS_STATUS_SUCCESS)	/* We found the entry. */

	    break;

	  /* We couldn't parse the entry */

	  else if (status == NSS_STATUS_RETURN

		   /* entry doesn't exist */

		   || status == NSS_STATUS_NOTFOUND)

	    continue;

	  else

	    {

	      if (status == NSS_STATUS_TRYAGAIN)

		{

		  fsetpos (ent->stream, &pos;;

		  *errnop = ERANGE;

		}

	      return status;

	    }

	}

      /* +:... */

      if (result->sp_namp[0] == '+' && result->sp_namp[1] == '\0')

	{

	  ent->files = false;

	  ent->first = true;

	  copy_spwd_changes (&ent->pwd, result, NULL, 0);

	  return getspent_next_nss (result, ent, buffer, buflen, errnop);

	}

    }

  return NSS_STATUS_SUCCESS;

}

static enum nss_status

internal_getspent_r (struct spwd *pw, ent_t *ent,

		     char *buffer, size_t buflen, int *errnop)

{

  if (ent->netgroup)

    {

      enum nss_status status;

      /* We are searching members in a netgroup */

      /* Since this is not the first call, we don't need the group name */

      status = getspent_next_nss_netgr (NULL, pw, ent, NULL, buffer,

					buflen, errnop);

      if (status == NSS_STATUS_RETURN)

	return getspent_next_file (pw, ent, buffer, buflen, errnop);

      else

	return status;

    }

  else if (ent->files)

    return getspent_next_file (pw, ent, buffer, buflen, errnop);

  else

    return getspent_next_nss (pw, ent, buffer, buflen, errnop);

}

enum nss_status

_nss_compat_getspent_r (struct spwd *pwd, char *buffer, size_t buflen,

			int *errnop)

{

  enum nss_status result = NSS_STATUS_SUCCESS;

  __libc_lock_lock (lock);

  /* Be prepared that the setpwent function was not called before.  */

  if (ni == NULL)

    init_nss_interface ();

  if (ext_ent.stream == NULL)

    result = internal_setspent (&ext_ent, 1, 1);

  if (result == NSS_STATUS_SUCCESS)

    result = internal_getspent_r (pwd, &ext_ent, buffer, buflen, errnop);

  __libc_lock_unlock (lock);

  return result;

}

/* Searches in /etc/passwd and the NIS/NIS+ map for a special user */

static enum nss_status

internal_getspnam_r (const char *name, struct spwd *result, ent_t *ent,

		     char *buffer, size_t buflen, int *errnop)

{

  struct parser_data *data = (void *) buffer;

  while (1)

    {

      fpos_t pos;

      char *p;

      int parse_res;

      do

	{

	  /* We need at least 3 characters for one line.  */

	  if (__glibc_unlikely (buflen < 3))

	    {

	    erange:

	      *errnop = ERANGE;

	      return NSS_STATUS_TRYAGAIN;

	    }

	  fgetpos (ent->stream, &pos;;

	  buffer[buflen - 1] = '\xff';

	  p = fgets_unlocked (buffer, buflen, ent->stream);

	  if (p == NULL && feof_unlocked (ent->stream))

	    return NSS_STATUS_NOTFOUND;

	  if (p == NULL || buffer[buflen - 1] != '\xff')

	    {

	    erange_reset:

	      fsetpos (ent->stream, &pos;;

	      goto erange;

	    }

          /* Terminate the line for any case.  */

	  buffer[buflen - 1] = '\0';

	  /* Skip leading blanks.  */

	  while (isspace (*p))

	    ++p;

	}

      while (*p == '\0' || *p == '#' ||	/* Ignore empty and comment lines.  */

	     /* Parse the line.  If it is invalid, loop to

	        get the next line of the file to parse.  */

	     !(parse_res = _nss_files_parse_spent (p, result, data, buflen,

						   errnop)));

      if (__glibc_unlikely (parse_res == -1))

	/* The parser ran out of space.  */

	goto erange_reset;

      /* This is a real entry.  */

      if (result->sp_namp[0] != '+' && result->sp_namp[0] != '-')

	{

	  if (strcmp (result->sp_namp, name) == 0)

	    return NSS_STATUS_SUCCESS;

	  else

	    continue;

	}

      /* -@netgroup */

      /* If the loaded NSS module does not support this service, add

         all users from a +@netgroup entry to the blacklist, too.  */

      if (result->sp_namp[0] == '-' && result->sp_namp[1] == '@'

	  && result->sp_namp[2] != '\0')

	{

	  if (innetgr (&result->sp_namp[2], NULL, name, NULL))

	    return NSS_STATUS_NOTFOUND;

	  continue;

	}

      /* +@netgroup */

      if (result->sp_namp[0] == '+' && result->sp_namp[1] == '@'

	  && result->sp_namp[2] != '\0')

	{

	  enum nss_status status;

	  if (innetgr (&result->sp_namp[2], NULL, name, NULL))

	    {

	      status = getspnam_plususer (name, result, ent, buffer,

					  buflen, errnop);

	      if (status == NSS_STATUS_RETURN)

		continue;

	      return status;

	    }

	  continue;

	}

      /* -user */

      if (result->sp_namp[0] == '-' && result->sp_namp[1] != '\0'

	  && result->sp_namp[1] != '@')

	{

	  if (strcmp (&result->sp_namp[1], name) == 0)

	    return NSS_STATUS_NOTFOUND;

	  else

	    continue;

	}

      /* +user */

      if (result->sp_namp[0] == '+' && result->sp_namp[1] != '\0'

	  && result->sp_namp[1] != '@')

	{

	  if (strcmp (name, &result->sp_namp[1]) == 0)

	    {

	      enum nss_status status;

	      status = getspnam_plususer (name, result, ent,

					  buffer, buflen, errnop);

	      if (status == NSS_STATUS_RETURN)

		/* We couldn't parse the entry */

		return NSS_STATUS_NOTFOUND;

	      else

		return status;

	    }

	}

      /* +:... */

      if (result->sp_namp[0] == '+' && result->sp_namp[1] == '\0')

	{

	  enum nss_status status;

	  status = getspnam_plususer (name, result, ent,

				      buffer, buflen, errnop);

	  if (status == NSS_STATUS_SUCCESS)

	    /* We found the entry. */

            break;

          else if (status == NSS_STATUS_RETURN)

	    /* We couldn't parse the entry */

            return NSS_STATUS_NOTFOUND;

	  else

	    return status;

	}

    }

  return NSS_STATUS_SUCCESS;

}

enum nss_status

_nss_compat_getspnam_r (const char *name, struct spwd *pwd,

			char *buffer, size_t buflen, int *errnop)

{

  enum nss_status result;

  ent_t ent = { false, true, false, NSS_STATUS_SUCCESS, NULL, { NULL, 0, 0},

		{ NULL, NULL, 0, 0, 0, 0, 0, 0, 0}};

  if (name[0] == '-' || name[0] == '+')

    return NSS_STATUS_NOTFOUND;

  __libc_lock_lock (lock);

  if (ni == NULL)

    init_nss_interface ();

  __libc_lock_unlock (lock);

  result = internal_setspent (&ent, 0, 0);

  if (result == NSS_STATUS_SUCCESS)

    result = internal_getspnam_r (name, pwd, &ent, buffer, buflen, errnop);

  internal_endspent (&ent;;

  return result;

}

/* Support routines for remembering -@netgroup and -user entries.

   The names are stored in a single string with `|' as separator. */

static void

blacklist_store_name (const char *name, ent_t *ent)

{

  int namelen = strlen (name);

  char *tmp;

  /* first call, setup cache */

  if (ent->blacklist.size == 0)

    {

      ent->blacklist.size = MAX (BLACKLIST_INITIAL_SIZE, 2 * namelen);

      ent->blacklist.data = malloc (ent->blacklist.size);

      if (ent->blacklist.data == NULL)

	return;

      ent->blacklist.data[0] = '|';

      ent->blacklist.data[1] = '\0';

      ent->blacklist.current = 1;

    }

  else

    {

      if (in_blacklist (name, namelen, ent))

	return;			/* no duplicates */

      if (ent->blacklist.current + namelen + 1 >= ent->blacklist.size)

	{

	  ent->blacklist.size += MAX (BLACKLIST_INCREMENT, 2 * namelen);

	  tmp = realloc (ent->blacklist.data, ent->blacklist.size);

	  if (tmp == NULL)

	    {

	      free (ent->blacklist.data);

	      ent->blacklist.size = 0;

	      return;

	    }

	  ent->blacklist.data = tmp;

	}

    }

  tmp = stpcpy (ent->blacklist.data + ent->blacklist.current, name);

  *tmp++ = '|';

  *tmp = '\0';

  ent->blacklist.current += namelen + 1;

  return;

}

/* Returns whether ent->blacklist contains name.  */

static bool

in_blacklist (const char *name, int namelen, ent_t *ent)

{

  char buf[namelen + 3];

  char *cp;

  if (ent->blacklist.data == NULL)

    return false;

  buf[0] = '|';

  cp = stpcpy (&buf[1], name);

  *cp++ = '|';

  *cp = '\0';

  return strstr (ent->blacklist.data, buf) != NULL;

}