/* Common code for file-based databases in nss_files module.

   Copyright (C) 1996-2013 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   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 <nss.h>

#include <stdio.h>

#include <ctype.h>

#include <errno.h>

#include <fcntl.h>

#include "compat.h"

/* These symbols are defined by the including source file:

   ENTNAME -- database name of the structure and functions (hostent, pwent).

   STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).

   DATABASE -- string of the database file's name ("hosts", "passwd").

   NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.

   Also see files-parse.c.

*/

#define ENTNAME_r	CONCAT(ENTNAME,_r)

#define DATAFILE	ALTFILES_DATADIR "/" DATABASE

#ifdef NEED_H_ERRNO

# include <netdb.h>

# define H_ERRNO_PROTO	, int *herrnop

# define H_ERRNO_ARG	, herrnop

# define H_ERRNO_SET(val) (*herrnop = (val))

#else

# define H_ERRNO_PROTO

# define H_ERRNO_ARG

# define H_ERRNO_SET(val) ((void) 0)

#endif

#ifndef EXTRA_ARGS

# define EXTRA_ARGS

# define EXTRA_ARGS_DECL

# define EXTRA_ARGS_VALUE

#endif

/* Locks the static variables in this file.  */

__libc_lock_define_initialized (static, lock)

/* Maintenance of the shared stream open on the database file.  */

static FILE *stream;

static fpos_t position;

static enum { nouse, getent, getby } last_use;

static int keep_stream;

/* Open database file if not already opened.  */

static enum nss_status

internal_setent (int stayopen)

{

  enum nss_status status = NSS_STATUS_SUCCESS;

  if (stream == NULL)

    {

      stream = fopen (DATAFILE, "rce");

      if (stream == NULL)

	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;

      else

	{

#if !defined O_CLOEXEC || !defined __ASSUME_O_CLOEXEC

# ifdef O_CLOEXEC

	  if (__have_o_cloexec <= 0)

# endif

	    {

	      /* We have to make sure the file is  `closed on exec'.  */

	      int result;

	      int flags;

	      result = flags = fcntl (fileno (stream), F_GETFD, 0);

	      if (result >= 0)

		{

# ifdef O_CLOEXEC

		  if (__have_o_cloexec == 0)

		    __have_o_cloexec = (flags & FD_CLOEXEC) == 0 ? -1 : 1;

		  if (__have_o_cloexec < 0)

# endif

		    {

		      flags |= FD_CLOEXEC;

		      result = fcntl (fileno (stream), F_SETFD, flags);

		    }

		}

	      if (result < 0)

		{

		  /* Something went wrong.  Close the stream and return a

		     failure.  */

		  fclose (stream);

		  stream = NULL;

		  status = NSS_STATUS_UNAVAIL;

		}

	    }

#endif

	}

    }

  else

    rewind (stream);

  /* Remember STAYOPEN flag.  */

  if (stream != NULL)

    keep_stream |= stayopen;

  return status;

}

/* Thread-safe, exported version of that.  */

enum nss_status

CONCAT(CONCAT(CONCAT(_nss_, ALTFILES_MODULE_NAME), _set), ENTNAME) (int stayopen)

{

  enum nss_status status;

  __libc_lock_lock (lock);

  status = internal_setent (stayopen);

  if (status == NSS_STATUS_SUCCESS && fgetpos (stream, &position) < 0)

    {

      fclose (stream);

      stream = NULL;

      status = NSS_STATUS_UNAVAIL;

    }

  last_use = getent;

  __libc_lock_unlock (lock);

  return status;

}

/* Close the database file.  */

static void

internal_endent (void)

{

  if (stream != NULL)

    {

      fclose (stream);

      stream = NULL;

    }

}

/* Thread-safe, exported version of that.  */

enum nss_status

CONCAT(CONCAT(CONCAT(_nss_, ALTFILES_MODULE_NAME), _end), ENTNAME) (void)

{

  __libc_lock_lock (lock);

  internal_endent ();

  /* Reset STAYOPEN flag.  */

  keep_stream = 0;

  __libc_lock_unlock (lock);

  return NSS_STATUS_SUCCESS;

}

/* Parsing the database file into `struct STRUCTURE' data structures.  */

static enum nss_status

internal_getent (struct STRUCTURE *result,

		 char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO

		 EXTRA_ARGS_DECL)

{

  char *p;

  struct parser_data *data = (void *) buffer;

  int linebuflen = buffer + buflen - data->linebuffer;

  int parse_result;

  if (buflen < sizeof *data + 2)

    {

      *errnop = ERANGE;

      H_ERRNO_SET (NETDB_INTERNAL);

      return NSS_STATUS_TRYAGAIN;

    }

  do

    {

      /* Terminate the line so that we can test for overflow.  */

      ((unsigned char *) data->linebuffer)[linebuflen - 1] = '\xff';

      p = fgets_unlocked (data->linebuffer, linebuflen, stream);

      if (p == NULL)

	{

	  /* End of file or read error.  */

	  H_ERRNO_SET (HOST_NOT_FOUND);

	  return NSS_STATUS_NOTFOUND;

	}

      else if (((unsigned char *) data->linebuffer)[linebuflen - 1] != 0xff)

	{

	  /* The line is too long.  Give the user the opportunity to

	     enlarge the buffer.  */

	  *errnop = ERANGE;

	  H_ERRNO_SET (NETDB_INTERNAL);

	  return NSS_STATUS_TRYAGAIN;

	}

      /* 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_result = parse_line (p, result, data, buflen, errnop

					  EXTRA_ARGS)));

  if (__builtin_expect (parse_result == -1, 0))

    {

      H_ERRNO_SET (NETDB_INTERNAL);

      return NSS_STATUS_TRYAGAIN;

    }

  /* Filled in RESULT with the next entry from the database file.  */

  return NSS_STATUS_SUCCESS;

}

/* Return the next entry from the database file, doing locking.  */

enum nss_status

CONCAT(CONCAT(CONCAT(_nss_, ALTFILES_MODULE_NAME), _get), ENTNAME_r) (struct STRUCTURE *result, char *buffer,

				  size_t buflen, int *errnop H_ERRNO_PROTO)

{

  /* Return next entry in host file.  */

  enum nss_status status = NSS_STATUS_SUCCESS;

  __libc_lock_lock (lock);

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

  if (stream == NULL)

    {

      int save_errno = errno;

      status = internal_setent (0);

      __set_errno (save_errno);

      if (status == NSS_STATUS_SUCCESS && fgetpos (stream, &position) < 0)

	{

	  fclose (stream);

	  stream = NULL;

	  status = NSS_STATUS_UNAVAIL;

	}

    }

  if (status == NSS_STATUS_SUCCESS)

    {

      /* If the last use was not by the getent function we need the

	 position the stream.  */

      if (last_use != getent)

	{

	  if (fsetpos (stream, &position) < 0)

	    status = NSS_STATUS_UNAVAIL;

	  else

	    last_use = getent;

	}

      if (status == NSS_STATUS_SUCCESS)

	{

	  status = internal_getent (result, buffer, buflen, errnop

				    H_ERRNO_ARG EXTRA_ARGS_VALUE);

	  /* Remember this position if we were successful.  If the

	     operation failed we give the user a chance to repeat the

	     operation (perhaps the buffer was too small).  */

	  if (status == NSS_STATUS_SUCCESS)

	    fgetpos (stream, &position);

	  else

	    /* We must make sure we reposition the stream the next call.  */

	    last_use = nouse;

	}

    }

  __libc_lock_unlock (lock);

  return status;

}

/* Macro for defining lookup functions for this file-based database.

   NAME is the name of the lookup; e.g. `hostbyname'.

   DB_CHAR, KEYPATTERN, KEYSIZE are ignored here but used by db-XXX.c

   e.g. `1 + sizeof (id) * 4'.

   PROTO is the potentially empty list of other parameters.

   BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'

   to the lookup key arguments and does `break;' if they match.  */

#define DB_LOOKUP(name, db_char, keysize, keypattern, break_if_match, proto...)\

enum nss_status								      \

CONCAT(CONCAT(_nss_, ALTFILES_MODULE_NAME), _get ## name ## _r) (proto,	      \

			  struct STRUCTURE *result, char *buffer,	      \

			  size_t buflen, int *errnop H_ERRNO_PROTO)	      \

{									      \

  enum nss_status status;						      \

									      \

  __libc_lock_lock (lock);						      \

									      \

  /* Reset file pointer to beginning or open file.  */			      \

  status = internal_setent (keep_stream);				      \

									      \

  if (status == NSS_STATUS_SUCCESS)					      \

    {									      \

      /* Tell getent function that we have repositioned the file pointer.  */ \

      last_use = getby;							      \

									      \

      while ((status = internal_getent (result, buffer, buflen, errnop	      \

					H_ERRNO_ARG EXTRA_ARGS_VALUE))	      \

	     == NSS_STATUS_SUCCESS)					      \

	{ break_if_match }						      \

									      \

      if (! keep_stream)						      \

	internal_endent ();						      \

    }									      \

									      \

  __libc_lock_unlock (lock);						      \

									      \

  return status;							      \

}