glibc/nss/getXXent_r.c

/* Copyright (C) 1996 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <bits/libc-lock.h>

#include "nsswitch.h"

/*******************************************************************\
|* Here we assume several symbols to be defined:		   *|
|* 								   *|
|* LOOKUP_TYPE   - the return type of the function		   *|
|* 								   *|
|* SETFUNC_NAME  - name of the non-reentrant setXXXent function	   *|
|* 								   *|
|* GETFUNC_NAME  - name of the non-reentrant getXXXent function	   *|
|* 								   *|
|* ENDFUNC_NAME  - name of the non-reentrant endXXXent function	   *|
|* 								   *|
|* DATABASE_NAME - name of the database the function accesses	   *|
|*		   (e.g., host, services, ...)			   *|
|* 								   *|
|* Optionally the following vars can be defined:		   *|
|* 								   *|
|* STAYOPEN      - variable declaration for setXXXent function	   *|
|* 								   *|
|* STAYOPEN_VAR  - variable name for setXXXent function		   *|
|* 								   *|
|* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
|*		   the global `h_errno' variable.		   *|
|* 								   *|
\*******************************************************************/

/* To make the real sources a bit prettier.  */
#define REENTRANT_GETNAME APPEND_R (GETFUNC_NAME)
#define APPEND_R(Name) CONCAT2_2 (Name, _r)
#define INTERNAL(Name) CONCAT2_2 (__, Name)
#define CONCAT2_1(Pre, Post) CONCAT2_2 (Pre, Post)
#define CONCAT2_2(Pre, Post) Pre##Post

#define SETFUNC_NAME_STRING STRINGIZE (SETFUNC_NAME)
#define GETFUNC_NAME_STRING STRINGIZE (REENTRANT_GETNAME)
#define ENDFUNC_NAME_STRING STRINGIZE (ENDFUNC_NAME)
#define DATABASE_NAME_STRING STRINGIZE (DATABASE_NAME)
#define STRINGIZE(Name) STRINGIZE1 (Name)
#define STRINGIZE1(Name) #Name

#define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup)
#define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
#define CONCAT3_2(Pre, Name, Post) Pre##Name##Post

/* Sometimes we need to store error codes in the `h_errno' variable.  */
#ifdef NEED_H_ERRNO
# define H_ERRNO_PARM , int *h_errnop
# define H_ERRNO_VAR , &h_errno
#else
# define H_ERRNO_PARM
# define H_ERRNO_VAR
#endif

/* Some databases take the `stayopen' flag.  */
#ifdef STAYOPEN
# define STAYOPEN_TMP CONCAT2_1 (STAYOPEN, _tmp)
# define STAYOPEN_TMPVAR CONCAT2_1 (STAYOPEN_VAR, _tmp)
#else
# define STAYOPEN void
# define STAYOPEN_VAR
# define STAYOPEN_TMPVAR
#endif

/* Prototype for the setXXXent functions we use here.  */
typedef int (*set_function) (STAYOPEN);

/* Prototype for the endXXXent functions we use here.  */
typedef int (*end_function) (void);

/* Prototype for the setXXXent functions we use here.  */
typedef int (*get_function) (LOOKUP_TYPE *, char *, size_t H_ERRNO_PARM);


/* This handle for the NSS data base is shared between all
   set/get/endXXXent functions.  */
static service_user *nip;
/* Remember the last service used since the last call to  `endXXent'.  */
static service_user *last_nip;
/* Remember the first service_entry, it's always the same.  */
static service_user *startp;

#ifdef STAYOPEN_TMP
/* We need to remember the last `stayopen' flag given by the user
   since the `setent' function is only called for the first available
   service.  */
static STAYOPEN_TMP;
#endif

/* Protect above variable against multiple uses at the same time.  */
__libc_lock_define_initialized (static, lock)

/* The lookup function for the first entry of this service.  */
extern int DB_LOOKUP_FCT (service_user **nip, const char *name, void **fctp);

/* Set up NIP to run through the services.  If ALL is zero, use NIP's
   current location if it's not nil.  Return nonzero if there are no
   services (left).  */
static enum nss_status
setup (void **fctp, const char *func_name, int all)
{
  int no_more;
  if (startp == NULL)
    {
      no_more = DB_LOOKUP_FCT (&nip, func_name, fctp);
      startp = no_more ? (service_user *) -1l : nip;
    }
  else if (startp == (service_user *) -1l)
    /* No services at all.  */
    return 1;
  else
    {
      if (all || !nip)
	/* Reset to the beginning of the service list.  */
	nip = startp;
      /* Look up the first function.  */
      no_more = __nss_lookup (&nip, func_name, fctp);
    }
  return no_more;
}

void
SETFUNC_NAME (STAYOPEN)
{
  set_function fct;
  int no_more;

#ifdef NEED__RES
  if ((_res.options & RES_INIT) == 0 && res_init () == -1)
    {
      __set_h_errno (NETDB_INTERNAL);
      return;
    }
#endif /* need _res */

  __libc_lock_lock (lock);

  /* Cycle through the services and run their `setXXent' functions until
     we find an available service.  */
  no_more = setup ((void **) &fct, SETFUNC_NAME_STRING, 1);
  while (! no_more)
    {
      int is_last_nip = nip == last_nip;
      enum nss_status status = (*fct) (STAYOPEN_VAR);

      no_more = __nss_next (&nip, SETFUNC_NAME_STRING, (void **) &fct,
			    status, 0);
      if (is_last_nip)
	last_nip = nip;
    }

#ifdef STAYOPEN_TMP
  STAYOPEN_TMPVAR = STAYOPEN_VAR;
#endif

  __libc_lock_unlock (lock);
}


void
ENDFUNC_NAME (void)
{
  end_function fct;
  int no_more;

#ifdef NEED__RES
  if ((_res.options & RES_INIT) == 0 && res_init () == -1)
    {
      __set_h_errno (NETDB_INTERNAL);
      return;
    }
#endif /* need _res */

  __libc_lock_lock (lock);

  /* Cycle through all the services and run their endXXent functions.  */
  no_more = setup ((void **) &fct, ENDFUNC_NAME_STRING, 1);
  while (! no_more)
    {
      /* Ignore status, we force check in __NSS_NEXT.  */
      (void) (*fct) ();

      if (nip == last_nip)
	/* We have processed all services which were used.  */
	break;

      no_more = __nss_next (&nip, ENDFUNC_NAME_STRING, (void **) &fct, 0, 1);
    }
  last_nip = nip = NULL;

  __libc_lock_unlock (lock);
}


int
INTERNAL (REENTRANT_GETNAME) (LOOKUP_TYPE *resbuf, char *buffer, size_t buflen,
			      LOOKUP_TYPE **result H_ERRNO_PARM)
{
  get_function fct;
  int no_more;
  enum nss_status status;

#ifdef NEED__RES
  if ((_res.options & RES_INIT) == 0 && res_init () == -1)
    {
      __set_h_errno (NETDB_INTERNAL);
      *result = NULL;
      return -1;
    }
#endif /* need _res */

  /* Initialize status to return if no more functions are found.  */
  status = NSS_STATUS_NOTFOUND;

  __libc_lock_lock (lock);

  /* Run through available functions, starting with the same function last
     run.  We will repeat each function as long as it succeeds, and then go
     on to the next service action.  */
  no_more = setup ((void **) &fct, GETFUNC_NAME_STRING, 0);
  while (! no_more)
    {
      int is_last_nip = nip == last_nip;
      service_user *current_nip = nip;

      status = (*fct) (resbuf, buffer, buflen H_ERRNO_VAR);

      no_more = __nss_next (&nip, GETFUNC_NAME_STRING, (void **) &fct,
			    status, 0);

      if (is_last_nip)
	last_nip = nip;

      if (! no_more && current_nip != nip)
	/* Call the `setXXent' function.  This wasn't done before.  */
	do
	  {
	    set_function sfct;

	    no_more = __nss_lookup (&nip, SETFUNC_NAME_STRING,
				    (void **) &sfct);

	    if (! no_more)
	      status = (*sfct) (STAYOPEN_TMPVAR);
	    else
	      status = NSS_STATUS_NOTFOUND;
	  }
	while (! no_more && status != NSS_STATUS_SUCCESS);
    }

  __libc_lock_unlock (lock);

  *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
  return status == NSS_STATUS_SUCCESS ? 0 : -1;
}
#define do_weak_alias(n1, n2) weak_alias (n1, n2)
do_weak_alias (INTERNAL (REENTRANT_GETNAME), REENTRANT_GETNAME)