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

   Copyright (C) 1996-2018 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 <stdio.h>

#include <ctype.h>

#include <errno.h>

#include <fcntl.h>

#include <libc-lock.h>

#include "nsswitch.h"

#include <nss_files.h>

#include <kernel-features.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	"/etc/" 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 stream open on the database file.  For getXXent

   operations the stream needs to be held open across calls, the other

   getXXbyYY operations all use their own stream.  */

static FILE *stream;

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

static enum nss_status

internal_setent (FILE **stream)

{

  enum nss_status status = NSS_STATUS_SUCCESS;

  if (*stream == NULL)

    {

      *stream = __nss_files_fopen (DATAFILE);

      if (*stream == NULL)

	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;

    }

  else

    rewind (*stream);

  return status;

}

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

enum nss_status

CONCAT(_nss_files_set,ENTNAME) (int stayopen)

{

  enum nss_status status;

  __libc_lock_lock (lock);

  status = internal_setent (&stream);

  __libc_lock_unlock (lock);

  return status;

}

/* Close the database file.  */

static void

internal_endent (FILE **stream)

{

  if (*stream != NULL)

    {

      fclose (*stream);

      *stream = NULL;

    }

}

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

enum nss_status

CONCAT(_nss_files_end,ENTNAME) (void)

{

  __libc_lock_lock (lock);

  internal_endent (&stream);

  __libc_lock_unlock (lock);

  return NSS_STATUS_SUCCESS;

}

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

static enum nss_status

internal_getent (FILE *stream, struct STRUCTURE *result,

		 char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO

		 EXTRA_ARGS_DECL)

{

  char *p;

  struct parser_data *data = (void *) buffer;

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

  int parse_result;

  if (buflen < sizeof *data + 2)

    {

      *errnop = ERANGE;

      H_ERRNO_SET (NETDB_INTERNAL);

      return NSS_STATUS_TRYAGAIN;

    }

  while (true)

    {

      ssize_t r = __libc_readline_unlocked

	(stream, data->linebuffer, linebuflen);

      if (r < 0)

	{

	  *errnop = errno;

	  H_ERRNO_SET (NETDB_INTERNAL);

	  if (*errnop == ERANGE)

	    /* Request larger buffer.  */

	    return NSS_STATUS_TRYAGAIN;

	  else

	    /* Other read failure.  */

	    return NSS_STATUS_UNAVAIL;

	}

      else if (r == 0)

	{

	  /* End of file.  */

	  H_ERRNO_SET (HOST_NOT_FOUND);

	  return NSS_STATUS_NOTFOUND;

	}

      /* Everything OK.  Now skip leading blanks.  */

      p = data->linebuffer;

      while (isspace (*p))

	++p;

      /* Ignore empty and comment lines.  */

      if (*p == '\0' || *p == '#')

	continue;

      /* Parse the line.   */

      *errnop = EINVAL;

      parse_result = parse_line (p, result, data, buflen, errnop EXTRA_ARGS);

      if (parse_result == -1)

	{

	  if (*errnop == ERANGE)

	    {

	      /* Return to the original file position at the beginning

		 of the line, so that the next call can read it again

		 if necessary.  */

	      if (__fseeko64 (stream, -r, SEEK_CUR) != 0)

		{

		  if (errno == ERANGE)

		    *errnop = EINVAL;

		  else

		    *errnop = errno;

		  H_ERRNO_SET (NETDB_INTERNAL);

		  return NSS_STATUS_UNAVAIL;

		}

	    }

	  H_ERRNO_SET (NETDB_INTERNAL);

	  return NSS_STATUS_TRYAGAIN;

	}

      /* Return the data if parsed successfully.  */

      if (parse_result != 0)

	return NSS_STATUS_SUCCESS;

      /* If it is invalid, loop to get the next line of the file to

	 parse.  */

    }

}

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

enum nss_status

CONCAT(_nss_files_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 (&stream);

      __set_errno (save_errno);

    }

  if (status == NSS_STATUS_SUCCESS)

    status = internal_getent (stream, result, buffer, buflen, errnop

			      H_ERRNO_ARG EXTRA_ARGS_VALUE);

  __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								      \

_nss_files_get##name##_r (proto,					      \

			  struct STRUCTURE *result, char *buffer,	      \

			  size_t buflen, int *errnop H_ERRNO_PROTO)	      \

{									      \

  enum nss_status status;						      \

  FILE *stream = NULL;							      \

									      \

  /* Open file.  */							      \

  status = internal_setent (&stream);					      \

									      \

  if (status == NSS_STATUS_SUCCESS)					      \

    {									      \

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

					H_ERRNO_ARG EXTRA_ARGS_VALUE))	      \

	     == NSS_STATUS_SUCCESS)					      \

	{ break_if_match }						      \

									      \

      internal_endent (&stream);					      \

    }									      \

									      \

  return status;							      \

}