port/gen/nsparse.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include "synonyms.h"
#include "mtlib.h"
#include "libc.h"
#include <synch.h>
#include <sys/types.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <dlfcn.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

#define	__NSS_PRIVATE_INTERFACE
#include "nsswitch_priv.h"
#undef	__NSS_PRIVATE_INTERFACE

#include <syslog.h>

#define	islabel(c) 	(isalnum(c) || (c) == '_')

#define	LIBC_STRDUP(new, existing) \
	if ((new = libc_strdup(existing)) == NULL) { \
		dup_fail = 1; \
		goto barf_line; \
	}

/*
 * This file has all the routines that access the configuration
 * information.
 */

struct cons_cell_v1 { /* private to the parser */
	struct __nsw_switchconfig_v1 *sw;
	struct cons_cell_v1 *next;
};

struct cons_cell { /* private to the parser */
	struct __nsw_switchconfig *sw;
	struct cons_cell *next;
};

/*
 * Local routines
 */

static char *skip(char **, char);
static char *labelskip(char *);
static char *spaceskip(char *);
static struct __nsw_switchconfig_v1 *scrounge_cache_v1(const char *);
static struct __nsw_switchconfig *scrounge_cache(const char *);
static int add_concell_v1(struct __nsw_switchconfig_v1 *);
static int add_concell(struct __nsw_switchconfig *);
static void freeconf_v1(struct __nsw_switchconfig_v1 *);
static void freeconf(struct __nsw_switchconfig *);
static int alldigits(char *);

static struct cons_cell_v1 *concell_list_v1; /* stays with add_concell() */
static struct cons_cell *concell_list; /* stays with add_concell() */

/*
 *
 * With the "lookup control" feature, the default criteria for NIS, NIS+,
 * and any new services (e.g. ldap) will be:
 *     [SUCCESS=return  NOTFOUND=continue UNAVAIL=continue TRYAGAIN=forever]
 *
 * For backward compat, NIS via NIS server in DNS forwarding mode will be:
 *     [SUCCESS=return  NOTFOUND=continue UNAVAIL=continue TRYAGAIN=continue]
 *
 * And also for backward compat, the default criteria for DNS will be:
 *     [SUCCESS=return  NOTFOUND=continue UNAVAIL=continue TRYAGAIN=continue]
 */


/*
 * The BIND resolver normally will retry several times on server non-response.
 * But now with the "lookup control" feature, we don't want the resolver doing
 * many retries, rather we want it to return control (reasonably) quickly back
 * to the switch engine.  However, when TRYAGAIN=N or TRYAGAIN=forever is
 * not explicitly set by the admin in the conf file, we want the old "resolver
 * retry a few times" rather than no retries at all.
 */
static int 	dns_tryagain_retry = 3;

/*
 * For backward compat (pre "lookup control"), the dns default behavior is
 * soft lookup.
 */
static void
set_dns_default_lkp(struct __nsw_lookup_v1 *lkp)
{
	if (strcasecmp(lkp->service_name, "dns") == 0) {
		lkp->actions[__NSW_TRYAGAIN] =
			__NSW_TRYAGAIN_NTIMES;
		lkp->max_retries = dns_tryagain_retry;
	}
}

/*
 * Private interface used by nss_common.c, hence this function is not static
 */
struct __nsw_switchconfig_v1 *
_nsw_getoneconfig_v1(const char *name, char *linep, enum __nsw_parse_err *errp)
	/* linep   Nota Bene: not const char *	*/
	/* errp  Meanings are abused a bit	*/
{
	struct __nsw_switchconfig_v1 *cfp;
	struct __nsw_lookup_v1 *lkp, **lkq;
	int end_crit, dup_fail = 0;
	action_t act;
	char *p, *tokenp;

	*errp = __NSW_CONF_PARSE_SUCCESS;

	if ((cfp = libc_malloc(sizeof (struct __nsw_switchconfig_v1)))
	    == NULL) {
		*errp = __NSW_CONF_PARSE_SYSERR;
		return (NULL);
	}
	LIBC_STRDUP(cfp->dbase, name);
	lkq = &cfp->lookups;

	/* linep points to a naming service name */
	for (;;) {
		int i;

		/* white space following the last service */
		if (*linep == '\0' || *linep == '\n') {
			return (cfp);
		}
		if ((lkp = libc_malloc(sizeof (struct __nsw_lookup_v1)))
		    == NULL) {
			*errp = __NSW_CONF_PARSE_SYSERR;
			freeconf_v1(cfp);
			return (NULL);
		}

		*lkq = lkp;
		lkq = &lkp->next;

		for (i = 0; i < __NSW_STD_ERRS_V1; i++)
			if (i == __NSW_SUCCESS)
				lkp->actions[i] = __NSW_RETURN;
			else if (i == __NSW_TRYAGAIN)
				lkp->actions[i] = __NSW_TRYAGAIN_FOREVER;
			else
				lkp->actions[i] = __NSW_CONTINUE;

		/* get criteria for the naming service */
		if (tokenp = skip(&linep, '[')) { /* got criteria */

			/* premature end, illegal char following [ */
			if (!islabel(*linep))
				goto barf_line;
			LIBC_STRDUP(lkp->service_name, tokenp);
			cfp->num_lookups++;

			set_dns_default_lkp(lkp);

			end_crit = 0;

			/* linep points to a switch_err */
			for (;;) {
				int ntimes = 0; /* try again max N times */
				int dns_continue = 0;

				if ((tokenp = skip(&linep, '=')) == NULL) {
					goto barf_line;
				}

				/* premature end, ill char following = */
				if (!islabel(*linep))
					goto barf_line;

				/* linep points to the string following '=' */
				p = labelskip(linep);
				if (*p == ']')
					end_crit = 1;
				else if (*p != ' ' && *p != '\t')
					goto barf_line;
				*p++ = '\0'; /* null terminate linep */
				p = spaceskip(p);
				if (!end_crit) {
					if (*p == ']') {
					end_crit = 1;
					*p++ = '\0';
					} else if (*p == '\0' || *p == '\n') {
						return (cfp);
					} else if (!islabel(*p))
					/* p better be the next switch_err */
						goto barf_line;
				}
				if (strcasecmp(linep, __NSW_STR_RETURN) == 0)
					act = __NSW_RETURN;
				else if (strcasecmp(linep,
						    __NSW_STR_CONTINUE) == 0) {
					if (strcasecmp(lkp->service_name,
						    "dns") == 0 &&
						strcasecmp(tokenp,
							__NSW_STR_TRYAGAIN)
							== 0) {
						/*
						 * Add one more condition
						 * so it retries only if it's
						 * "dns [TRYAGAIN=continue]"
						 */
						dns_continue = 1;
						act = __NSW_TRYAGAIN_NTIMES;
					} else
						act = __NSW_CONTINUE;
				} else if (strcasecmp(linep,
					    __NSW_STR_FOREVER) == 0)
					act = __NSW_TRYAGAIN_FOREVER;
				else if (alldigits(linep)) {
					act = __NSW_TRYAGAIN_NTIMES;
					ntimes = atoi(linep);
					if (ntimes < 0 || ntimes > INT_MAX)
						ntimes = 0;
				}
				else
					goto barf_line;

				if (__NSW_SUCCESS_ACTION(act) &&
				    strcasecmp(tokenp,
					    __NSW_STR_SUCCESS) == 0) {
					lkp->actions[__NSW_SUCCESS] = act;
				} else if (__NSW_NOTFOUND_ACTION(act) &&
					strcasecmp(tokenp,
					    __NSW_STR_NOTFOUND) == 0) {
					lkp->actions[__NSW_NOTFOUND] = act;
				} else if (__NSW_UNAVAIL_ACTION(act) &&
					strcasecmp(tokenp,
					    __NSW_STR_UNAVAIL) == 0) {
					lkp->actions[__NSW_UNAVAIL] = act;
				} else if (__NSW_TRYAGAIN_ACTION(act) &&
					strcasecmp(tokenp,
					    __NSW_STR_TRYAGAIN) == 0) {
					lkp->actions[__NSW_TRYAGAIN] = act;
					if (strcasecmp(lkp->service_name,
						    "nis") == 0)
						lkp->actions[
						    __NSW_NISSERVDNS_TRYAGAIN]
						    = act;
					if (act == __NSW_TRYAGAIN_NTIMES)
						lkp->max_retries =
						dns_continue ?
						dns_tryagain_retry : ntimes;
				} else {
					/*EMPTY*/
					/*
					 * convert string tokenp to integer
					 * and put in long_errs
					 */
				}
				if (end_crit) {
					linep = spaceskip(p);
					if (*linep == '\0' || *linep == '\n')
						return (cfp);
					break; /* process next naming service */
				}
				linep = p;
			} /* end of while loop for a name service's criteria */
		} else {
			/*
			 * no criteria for this naming service.
			 * linep points to name service, but not null
			 * terminated.
			 */
			p = labelskip(linep);
			if (*p == '\0' || *p == '\n') {
				*p = '\0';
				LIBC_STRDUP(lkp->service_name, linep);
				set_dns_default_lkp(lkp);
				cfp->num_lookups++;
				return (cfp);
			}
			if (*p != ' ' && *p != '\t')
				goto barf_line;
			*p++ = '\0';
			LIBC_STRDUP(lkp->service_name, linep);
			set_dns_default_lkp(lkp);
			cfp->num_lookups++;
			linep = spaceskip(p);
		}
	} /* end of while(1) loop for a name service */

barf_line:
	freeconf_v1(cfp);
	*errp = dup_fail ? __NSW_CONF_PARSE_SYSERR : __NSW_CONF_PARSE_NOPOLICY;
	return (NULL);
}

/*
 * Private interface used by nss_common.c, hence this function is not static
 */
struct __nsw_switchconfig *
_nsw_getoneconfig(const char *name, char *linep, enum __nsw_parse_err *errp)
	/* linep   Nota Bene: not const char *	*/
	/* errp  Meanings are abused a bit	*/
{
	struct __nsw_switchconfig *cfp;
	struct __nsw_lookup *lkp, **lkq;
	int end_crit, dup_fail = 0;
	action_t act;
	char *p, *tokenp;

	*errp = __NSW_CONF_PARSE_SUCCESS;

	if ((cfp = libc_malloc(sizeof (struct __nsw_switchconfig)))
	    == NULL) {
		*errp = __NSW_CONF_PARSE_SYSERR;
		return (NULL);
	}
	LIBC_STRDUP(cfp->dbase, name);
	lkq = &cfp->lookups;

	/* linep points to a naming service name */
	for (;;) {
		int i;

		/* white space following the last service */
		if (*linep == '\0' || *linep == '\n') {
			return (cfp);
		}
		if ((lkp = libc_malloc(sizeof (struct __nsw_lookup)))
		    == NULL) {
			*errp = __NSW_CONF_PARSE_SYSERR;
			freeconf(cfp);
			return (NULL);
		}

		*lkq = lkp;
		lkq = &lkp->next;

		for (i = 0; i < __NSW_STD_ERRS; i++)
			if (i == __NSW_SUCCESS)
				lkp->actions[i] = 1;
			else
				lkp->actions[i] = 0;

		/* get criteria for the naming service */
		if (tokenp = skip(&linep, '[')) { /* got criteria */

			/* premature end, illegal char following [ */
			if (!islabel(*linep))
				goto barf_line;
			LIBC_STRDUP(lkp->service_name, tokenp);
			cfp->num_lookups++;
			end_crit = 0;

			/* linep points to a switch_err */
			for (;;) {
				if ((tokenp = skip(&linep, '=')) == NULL) {
					goto barf_line;
				}

				/* premature end, ill char following = */
				if (!islabel(*linep))
					goto barf_line;

				/* linep points to the string following '=' */
				p = labelskip(linep);
				if (*p == ']')
					end_crit = 1;
				else if (*p != ' ' && *p != '\t')
					goto barf_line;
				*p++ = '\0'; /* null terminate linep */
				p = spaceskip(p);
				if (!end_crit) {
					if (*p == ']') {
					end_crit = 1;
					*p++ = '\0';
					} else if (*p == '\0' || *p == '\n')
						return (cfp);
					else if (!islabel(*p))
					/* p better be the next switch_err */
						goto barf_line;
				}
				if (strcasecmp(linep, __NSW_STR_RETURN) == 0)
					act = __NSW_RETURN;
				else if (strcasecmp(linep,
					    __NSW_STR_CONTINUE) == 0)
					act = __NSW_CONTINUE;
				else if (strcasecmp(linep,
					    __NSW_STR_FOREVER) == 0)
					/*
					 * =forever or =N might be in conf file
					 * but old progs won't expect it.
					 */
					act = __NSW_RETURN;
				else if (alldigits(linep))
					act = __NSW_CONTINUE;
				else
					goto barf_line;
				if (strcasecmp(tokenp,
					    __NSW_STR_SUCCESS) == 0) {
					lkp->actions[__NSW_SUCCESS] = act;
				} else if (strcasecmp(tokenp,
					    __NSW_STR_NOTFOUND) == 0) {
					lkp->actions[__NSW_NOTFOUND] = act;
				} else if (strcasecmp(tokenp,
					    __NSW_STR_UNAVAIL) == 0) {
					lkp->actions[__NSW_UNAVAIL] = act;
				} else if (strcasecmp(tokenp,
					    __NSW_STR_TRYAGAIN) == 0) {
					lkp->actions[__NSW_TRYAGAIN] = act;
				} else {
					/*EMPTY*/
					/*
					 * convert string tokenp to integer
					 * and put in long_errs
					 */
				}
				if (end_crit) {
					linep = spaceskip(p);
					if (*linep == '\0' || *linep == '\n')
						return (cfp);
					break; /* process next naming service */
				}
				linep = p;
			} /* end of while loop for a name service's criteria */
		} else {
			/*
			 * no criteria for this naming service.
			 * linep points to name service, but not null
			 * terminated.
			 */
			p = labelskip(linep);
			if (*p == '\0' || *p == '\n') {
				*p = '\0';
				LIBC_STRDUP(lkp->service_name, linep);
				cfp->num_lookups++;
				return (cfp);
			}
			if (*p != ' ' && *p != '\t')
				goto barf_line;
			*p++ = '\0';
			LIBC_STRDUP(lkp->service_name, linep);
			cfp->num_lookups++;
			linep = spaceskip(p);
		}
	} /* end of while(1) loop for a name service */

barf_line:
	freeconf(cfp);
	*errp = dup_fail ? __NSW_CONF_PARSE_SYSERR : __NSW_CONF_PARSE_NOPOLICY;
	return (NULL);
}

static mutex_t serialize_config_v1 = DEFAULTMUTEX;
static mutex_t serialize_config = DEFAULTMUTEX;

static void
syslog_warning(const char *dbase)
{
	syslog(LOG_WARNING,
	    "libc: bad lookup policy for %s in %s, using defaults..\n",
	    dbase, __NSW_CONFIG_FILE);
}

struct __nsw_switchconfig_v1 *
__nsw_getconfig_v1(const char *dbase, enum __nsw_parse_err *errp)
{
	struct __nsw_switchconfig_v1 *cfp, *retp = NULL;
	int syslog_error = 0;
	__NSL_FILE *fp;
	char *linep;
	char lineq[BUFSIZ];

	/*
	 * ==== I don't feel entirely comfortable disabling signals for the
	 *	duration of this, but maybe we have to.  Or maybe we should
	 *	use mutex_trylock to detect recursion?  (Not clear what's
	 *	the right thing to do when it happens, though).
	 */
	lmutex_lock(&serialize_config_v1);

	if (cfp = scrounge_cache_v1(dbase)) {
		*errp = __NSW_CONF_PARSE_SUCCESS;
		lmutex_unlock(&serialize_config_v1);
		return (cfp);
	}

	if ((fp = __nsl_c_fopen(__NSW_CONFIG_FILE, "r")) == NULL) {
		*errp = __NSW_CONF_PARSE_NOFILE;
		lmutex_unlock(&serialize_config_v1);
		return (NULL);
	}

	*errp = __NSW_CONF_PARSE_NOPOLICY;
	while (linep = __nsl_c_fgets(lineq, BUFSIZ, fp)) {
		enum __nsw_parse_err	line_err;
		char			*tokenp, *comment;

		/*
		 * Ignore portion of line following the comment character '#'.
		 */
		if ((comment = strchr(linep, '#')) != NULL) {
			*comment = '\0';
		}
		/*
		 * skip past blank lines.
		 * otherwise, cache as a struct switchconfig.
		 */
		if ((*linep == '\0') || isspace(*linep)) {
			continue;
		}
		if ((tokenp = skip(&linep, ':')) == NULL) {
			continue; /* ignore this line */
		}
		if (cfp = scrounge_cache_v1(tokenp)) {
			continue; /* ? somehow this database is in the cache */
		}
		if (cfp = _nsw_getoneconfig_v1(tokenp, linep, &line_err)) {
			(void) add_concell_v1(cfp);
			if (strcmp(cfp->dbase, dbase) == 0) {
				*errp = __NSW_CONF_PARSE_SUCCESS;
				retp = cfp;
			}
		} else {
			/*
			 * Got an error on this line, if it is a system
			 * error we might as well give right now. If it
			 * is a parse error on the second entry of the
			 * database we are looking for and the first one
			 * was a good entry we end up logging the following
			 * syslog message and using a default policy instead.
			 */
			if (line_err == __NSW_CONF_PARSE_SYSERR) {
				*errp = __NSW_CONF_PARSE_SYSERR;
				break;
			} else if (line_err == __NSW_CONF_PARSE_NOPOLICY &&
			    strcmp(tokenp, dbase) == 0) {
				syslog_error = 1;
				*errp = __NSW_CONF_PARSE_NOPOLICY;
				break;
			}
			/*
			 * Else blithely ignore problems on this line and
			 *   go ahead with the next line.
			 */
		}
	}
	(void) __nsl_c_fclose(fp);
	lmutex_unlock(&serialize_config_v1);
	/*
	 * We have to drop the lock before calling syslog().
	 */
	if (syslog_error)
		syslog_warning(dbase);
	return (retp);
}

struct __nsw_switchconfig *
__nsw_getconfig(const char *dbase, enum __nsw_parse_err *errp)
{
	struct __nsw_switchconfig *cfp, *retp = NULL;
	int syslog_error = 0;
	__NSL_FILE *fp;
	char *linep;
	char lineq[BUFSIZ];

	/*
	 * ==== I don't feel entirely comfortable disabling signals for the
	 *	duration of this, but maybe we have to.  Or maybe we should
	 *	use mutex_trylock to detect recursion?  (Not clear what's
	 *	the right thing to do when it happens, though).
	 */
	lmutex_lock(&serialize_config);

	if (cfp = scrounge_cache(dbase)) {
		*errp = __NSW_CONF_PARSE_SUCCESS;
		lmutex_unlock(&serialize_config);
		return (cfp);
	}

	if ((fp = __nsl_c_fopen(__NSW_CONFIG_FILE, "r")) == NULL) {
		*errp = __NSW_CONF_PARSE_NOFILE;
		lmutex_unlock(&serialize_config);
		return (NULL);
	}

	*errp = __NSW_CONF_PARSE_NOPOLICY;
	while (linep = __nsl_c_fgets(lineq, BUFSIZ, fp)) {
		enum __nsw_parse_err	line_err;
		char			*tokenp, *comment;

		/*
		 * Ignore portion of line following the comment character '#'.
		 */
		if ((comment = strchr(linep, '#')) != NULL) {
			*comment = '\0';
		}
		/*
		 * skip past blank lines.
		 * otherwise, cache as a struct switchconfig.
		 */
		if ((*linep == '\0') || isspace(*linep)) {
			continue;
		}
		if ((tokenp = skip(&linep, ':')) == NULL) {
			continue; /* ignore this line */
		}
		if (cfp = scrounge_cache(tokenp)) {
			continue; /* ? somehow this database is in the cache */
		}
		if (cfp = _nsw_getoneconfig(tokenp, linep, &line_err)) {
			(void) add_concell(cfp);
			if (strcmp(cfp->dbase, dbase) == 0) {
				*errp = __NSW_CONF_PARSE_SUCCESS;
				retp = cfp;
			}
		} else {
			/*
			 * Got an error on this line, if it is a system
			 * error we might as well give right now. If it
			 * is a parse error on the second entry of the
			 * database we are looking for and the first one
			 * was a good entry we end up logging the following
			 * syslog message and using a default policy instead.
			 */
			if (line_err == __NSW_CONF_PARSE_SYSERR) {
				*errp = __NSW_CONF_PARSE_SYSERR;
				break;
			} else if (line_err == __NSW_CONF_PARSE_NOPOLICY &&
			    strcmp(tokenp, dbase) == 0) {
				syslog_error = 1;
				*errp = __NSW_CONF_PARSE_NOPOLICY;
				break;
			}
			/*
			 * Else blithely ignore problems on this line and
			 *   go ahead with the next line.
			 */
		}
	}
	(void) __nsl_c_fclose(fp);
	lmutex_unlock(&serialize_config);
	/*
	 * We have to drop the lock before calling syslog().
	 */
	if (syslog_error)
		syslog_warning(dbase);
	return (retp);
}


static struct __nsw_switchconfig_v1 *
scrounge_cache_v1(const char *dbase)
{
	struct cons_cell_v1 *cellp = concell_list_v1;

	for (; cellp; cellp = cellp->next)
		if (strcmp(dbase, cellp->sw->dbase) == 0)
			return (cellp->sw);
	return (NULL);
}

static struct __nsw_switchconfig *
scrounge_cache(const char *dbase)
{
	struct cons_cell *cellp = concell_list;

	for (; cellp; cellp = cellp->next)
		if (strcmp(dbase, cellp->sw->dbase) == 0)
			return (cellp->sw);
	return (NULL);
}

static void
freeconf_v1(struct __nsw_switchconfig_v1 *cfp)
{
	if (cfp) {
		if (cfp->dbase)
			libc_free(cfp->dbase);
		if (cfp->lookups) {
			struct __nsw_lookup_v1 *nex, *cur;
			for (cur = cfp->lookups; cur; cur = nex) {
				libc_free(cur->service_name);
				nex = cur->next;
				libc_free(cur);
			}
		}
		libc_free(cfp);
	}
}

static void
freeconf(struct __nsw_switchconfig *cfp)
{
	if (cfp) {
		if (cfp->dbase)
			libc_free(cfp->dbase);
		if (cfp->lookups) {
			struct __nsw_lookup *nex, *cur;
			for (cur = cfp->lookups; cur; cur = nex) {
				libc_free(cur->service_name);
				nex = cur->next;
				libc_free(cur);
			}
		}
		libc_free(cfp);
	}
}

action_t
__nsw_extended_action_v1(struct __nsw_lookup_v1 *lkp, int err)
{
	struct __nsw_long_err *lerrp;

	for (lerrp = lkp->long_errs; lerrp; lerrp = lerrp->next) {
		if (lerrp->nsw_errno == err)
			return (lerrp->action);
	}
	return (__NSW_CONTINUE);
}

action_t
__nsw_extended_action(struct __nsw_lookup *lkp, int err)
{
	struct __nsw_long_err *lerrp;

	for (lerrp = lkp->long_errs; lerrp; lerrp = lerrp->next) {
		if (lerrp->nsw_errno == err)
			return (lerrp->action);
	}
	return (__NSW_CONTINUE);
}


/* give the next non-alpha character */
static char *
labelskip(char *cur)
{
	char *p = cur;
	while (islabel(*p))
		++p;
	return (p);
}

/* give the next non-space character */
static char *
spaceskip(char *cur)
{
	char *p = cur;
	while (*p == ' ' || *p == '\t')
		++p;
	return (p);
}

/*
 * terminate the *cur pointed string by null only if it is
 * followed by "key" surrounded by zero or more spaces and
 * return value is the same as the original *cur pointer and
 * *cur pointer is advanced to the first non {space, key} char
 * followed by the key. Otherwise, return NULL and keep
 * *cur unchanged.
 */
static char *
skip(char **cur, char key)
{
	char *p, *tmp;
	char *q = *cur;
	int found, tmpfound;

	tmp = labelskip(*cur);
	p = tmp;
	found = (*p == key);
	if (found) {
		*p++ = '\0'; /* overwrite the key */
		p = spaceskip(p);
	} else {
		while (*p == ' ' || *p == '\t') {
			tmpfound = (*++p == key);
			if (tmpfound) {
				found = tmpfound;
					/* null terminate the return token */
				*tmp = '\0';
				p++; /* skip the key */
			}
		}
	}
	if (!found)
		return (NULL); /* *cur unchanged */
	*cur = p;
	return (q);
}

/* add to the front: LRU */
static int
add_concell_v1(struct __nsw_switchconfig_v1 *cfp)
{
	struct cons_cell_v1 *cp;

	if (cfp == NULL)
		return (1);
	if ((cp = libc_malloc(sizeof (struct cons_cell_v1))) == NULL)
		return (1);
	cp->sw = cfp;
	cp->next = concell_list_v1;
	concell_list_v1 = cp;
	return (0);
}

/* add to the front: LRU */
static int
add_concell(struct __nsw_switchconfig *cfp)
{
	struct cons_cell *cp;

	if (cfp == NULL)
		return (1);
	if ((cp = libc_malloc(sizeof (struct cons_cell))) == NULL)
		return (1);
	cp->sw = cfp;
	cp->next = concell_list;
	concell_list = cp;
	return (0);
}

int
__nsw_freeconfig_v1(struct __nsw_switchconfig_v1 *conf)
{
	struct cons_cell_v1 *cellp;

	if (conf == NULL) {
		return (-1);
	}
	/*
	 * Hacked to make life easy for the code in nss_common.c.  Free conf
	 *   iff it was created by calling _nsw_getoneconfig() directly
	 *   rather than by calling nsw_getconfig.
	 */
	lmutex_lock(&serialize_config_v1);
	for (cellp = concell_list_v1;  cellp;  cellp = cellp->next) {
		if (cellp->sw == conf) {
			break;
		}
	}
	lmutex_unlock(&serialize_config_v1);
	if (cellp == NULL) {
		/* Not in the cache;  free it */
		freeconf_v1(conf);
		return (1);
	} else {
		/* In the cache;  don't free it */
		return (0);
	}
}

int
__nsw_freeconfig(struct __nsw_switchconfig *conf)
{
	struct cons_cell *cellp;

	if (conf == NULL) {
		return (-1);
	}
	/*
	 * Hacked to make life easy for the code in nss_common.c.  Free conf
	 *   iff it was created by calling _nsw_getoneconfig() directly
	 *   rather than by calling nsw_getconfig.
	 */
	lmutex_lock(&serialize_config);
	for (cellp = concell_list;  cellp;  cellp = cellp->next) {
		if (cellp->sw == conf) {
			break;
		}
	}
	lmutex_unlock(&serialize_config);
	if (cellp == NULL) {
		/* Not in the cache;  free it */
		freeconf(conf);
		return (1);
	} else {
		/* In the cache;  don't free it */
		return (0);
	}
}

/* Return 1 if the string contains all digits, else return 0. */
static int
alldigits(char *s)
{
	for (; *s; s++)
		if (!isdigit(*s))
			return (0);
	return (1);
}


/*
 * To avoid the 256 open file descriptor limitation in stdio,
 * we are using a  private limited implementation of stdio calls.
 * The private implementation is closely based on the implementation
 * in the standard C library.
 * To simplify, certain assumptions are made:
 * - a file may be opened only in read mode.
 * - Only sequential reads allowed
 * - file descriptors should not be shared between threads
 */

static int
_raise_fd(int fd)
{
	int nfd;
	static const int min_fd = 256;

	if (fd >= min_fd)
		return (fd);

	if ((nfd = fcntl(fd, F_DUPFD, min_fd)) == -1) {
		/*
		 * If the shell limits [See limit(1)] the
		 * descriptors to 256, fcntl will fail
		 * and errno will be set to EINVAL. Since
		 * the intention is to ignore fcntl failures
		 * and continue working with 'fd', we should
		 * reset errno to _prevent_ apps relying on errno
		 * to treat this as an error.
		 */
		errno = 0;
		return (fd);
	}

	(void) close(fd);

	return (nfd);
}

__NSL_FILE *
__nsl_c_fopen(const char *filename, const char *mode)
{
	int		fd;
	__NSL_FILE	*stream;
	void		*buf;

	if (mode == NULL || filename == NULL) {
		return (NULL);
	}

	if (strcmp(mode, "r") != 0) {
		return (NULL);
	}

	fd = open(filename, O_RDONLY | O_LARGEFILE, 0666);
	if (fd < 0)
		return (NULL);

	stream = libc_malloc(sizeof (__NSL_FILE));
	buf = lmalloc(__NSL_FILE_BUF_SIZE);
	if (stream != NULL && buf != NULL) {
		stream->_nsl_base = buf;
		stream->_nsl_file = _raise_fd(fd);
		stream->_nsl_cnt = 0;
		stream->_nsl_ptr = stream->_nsl_base;
	} else {
		(void) close(fd);
		if (buf)
			lfree(buf, __NSL_FILE_BUF_SIZE);
		if (stream)
			libc_free(stream);
		stream = NULL;
	}

	return (stream);
}

int
__nsl_c_fclose(__NSL_FILE *stream)
{
	int res = 0;

	if (stream == NULL)
		return (EOF);

	if (close(stream->_nsl_file) < 0)
		res = EOF;

	lfree(stream->_nsl_base, __NSL_FILE_BUF_SIZE);
	libc_free(stream);

	return (res);
}

char *
__nsl_c_fgets(char *buf, int size, __NSL_FILE *stream)
{
	char *ptr = buf;
	char *p;
	int n;
	int res;

	size--;		/* room for '\0' */
	while (size > 0) {
		if (stream->_nsl_cnt == 0) {
			stream->_nsl_ptr = stream->_nsl_base;

			if ((res = read(stream->_nsl_file, stream->_nsl_base,
				__NSL_FILE_BUF_SIZE)) > 0) {
				stream->_nsl_cnt = res;
			} else {
				stream->_nsl_cnt = 0;
				break;
			}
		}
		n = (int)(size < stream->_nsl_cnt ? size : stream->_nsl_cnt);
		if ((p = memccpy(ptr, (char *)stream->_nsl_ptr, '\n',
		    (size_t)n)) != NULL)
			n = (int)(p - ptr);
		ptr += n;
		stream->_nsl_cnt -= n;
		stream->_nsl_ptr += n;
		if (p != NULL)
			break; /* newline found */
		size -= n;
	}

	if (ptr == buf)	/* never read anything */
		return (NULL);

	*ptr = '\0';
	return (buf);
}