/*      $NetBSD: nsdispatch.c,v 1.9 1999/01/25 00:16:17 lukem Exp $     */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Luke Mewburn.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
/*-
 * Copyright (c) 2003 Networks Associates Technology, Inc.
 * All rights reserved.
 *
 * Portions of this software were developed for the FreeBSD Project by
 * Jacques A. Vidrine, Safeport Network Services, and Network
 * Associates Laboratories, the Security Research Division of Network
 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
 * ("CBOSS"), as part of the DARPA CHATS research program.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */
#include "namespace.h"
#include <sys/param.h>
#include <sys/stat.h>

#include <dlfcn.h>
#include <errno.h>
#include <fcntl.h>
#define _NS_PRIVATE
#include <nsswitch.h>
#include <pthread.h>
#include <pthread_np.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "un-namespace.h"
#include "nss_tls.h"
#include "libc_private.h"
#ifdef NS_CACHING
#include "nscache.h"
#endif

enum _nss_constants {
        /* Number of elements allocated when we grow a vector */
        ELEMSPERCHUNK = 8
};

/*
 * Global NSS data structures are mostly read-only, but we update
 * them when we read or re-read the nsswitch.conf.
 */
static  pthread_rwlock_t        nss_lock = PTHREAD_RWLOCK_INITIALIZER;

/*
 * Runtime determination of whether we are dynamically linked or not.
 */
extern  int             _DYNAMIC __attribute__ ((weak));
#define is_dynamic()    (&_DYNAMIC != NULL)

/*
 * default sourcelist: `files'
 */
const ns_src __nsdefaultsrc[] = {
        { NSSRC_FILES, NS_SUCCESS },
        { 0 },
};

/* Database, source mappings. */
static  unsigned int             _nsmapsize;
static  ns_dbt                  *_nsmap = NULL;

/* NSS modules. */
static  unsigned int             _nsmodsize;
static  ns_mod                  *_nsmod;

/* Placeholder for builtin modules' dlopen `handle'. */
static  int                      __nss_builtin_handle;
static  void                    *nss_builtin_handle = &__nss_builtin_handle;

#ifdef NS_CACHING
/*
 * Cache lookup cycle prevention function - if !NULL then no cache lookups
 * will be made
 */
static  void                    *nss_cache_cycle_prevention_func = NULL;
#endif

/*
 * We keep track of nsdispatch() nesting depth in dispatch_depth.  When a
 * fallback method is invoked from nsdispatch(), we temporarily set
 * fallback_depth to the current dispatch depth plus one.  Subsequent
 * calls at that exact depth will run in fallback mode (restricted to the
 * same source as the call that was handled by the fallback method), while
 * calls below that depth will be handled normally, allowing fallback
 * methods to perform arbitrary lookups.
 */
struct fb_state {
        int     dispatch_depth;
        int     fallback_depth;
};
static  void    fb_endstate(void *);
NSS_TLS_HANDLING(fb);

/*
 * Attempt to spew relatively uniform messages to syslog.
 */
#define nss_log(level, fmt, ...) \
        syslog((level), "NSSWITCH(%s): " fmt, __func__, __VA_ARGS__)
#define nss_log_simple(level, s) \
        syslog((level), "NSSWITCH(%s): " s, __func__)

/*
 * Dynamically growable arrays are used for lists of databases, sources,
 * and modules.  The following `vector' interface is used to isolate the
 * common operations.
 */
typedef int     (*vector_comparison)(const void *, const void *);
typedef void    (*vector_free_elem)(void *);
static  void      vector_sort(void *, unsigned int, size_t,
                    vector_comparison);
static  void      vector_free(void *, unsigned int *, size_t,
                    vector_free_elem);
static  void     *vector_ref(unsigned int, void *, unsigned int, size_t);
static  void     *vector_search(const void *, void *, unsigned int, size_t,
                    vector_comparison);
static  void     *vector_append(const void *, void *, unsigned int *, size_t);


/*
 * Internal interfaces.
 */
static  int      string_compare(const void *, const void *);
static  int      mtab_compare(const void *, const void *);
static  int      nss_configure(void);
static  void     ns_dbt_free(ns_dbt *);
static  void     ns_mod_free(ns_mod *);
static  void     ns_src_free(ns_src **, int);
static  void     nss_load_builtin_modules(void);
static  void     nss_load_module(const char *, nss_module_register_fn);
static  void     nss_atexit(void);
/* nsparser */
extern  FILE    *_nsyyin;


/*
 * The vector operations
 */
static void
vector_sort(void *vec, unsigned int count, size_t esize,
    vector_comparison comparison)
{
        qsort(vec, count, esize, comparison);
}


static void *
vector_search(const void *key, void *vec, unsigned int count, size_t esize,
    vector_comparison comparison)
{
        return (bsearch(key, vec, count, esize, comparison));
}


static void *
vector_append(const void *elem, void *vec, unsigned int *count, size_t esize)
{
        void    *p;

        if ((*count % ELEMSPERCHUNK) == 0) {
                p = reallocarray(vec, *count + ELEMSPERCHUNK, esize);
                if (p == NULL) {
                        nss_log_simple(LOG_ERR, "memory allocation failure");
                        return (vec);
                }
                vec = p;
        }
        memmove((void *)(((uintptr_t)vec) + (*count * esize)), elem, esize);
        (*count)++;
        return (vec);
}


static void *
vector_ref(unsigned int i, void *vec, unsigned int count, size_t esize)
{
        if (i < count)
                return (void *)((uintptr_t)vec + (i * esize));
        else
                return (NULL);
}


#define VECTOR_FREE(v, c, s, f) \
        do { vector_free(v, c, s, f); v = NULL; } while (0)
static void
vector_free(void *vec, unsigned int *count, size_t esize,
    vector_free_elem free_elem)
{
        unsigned int     i;
        void            *elem;

        for (i = 0; i < *count; i++) {
                elem = vector_ref(i, vec, *count, esize);
                if (elem != NULL)
                        free_elem(elem);
        }
        free(vec);
        *count = 0;
}

/*
 * Comparison functions for vector_search.
 */
static int
string_compare(const void *a, const void *b)
{
      return (strcasecmp(*(const char * const *)a, *(const char * const *)b));
}


static int
mtab_compare(const void *a, const void *b)
{
      int     cmp;

      cmp = strcmp(((const ns_mtab *)a)->name, ((const ns_mtab *)b)->name);
      if (cmp != 0)
              return (cmp);
      else
              return (strcmp(((const ns_mtab *)a)->database,
                  ((const ns_mtab *)b)->database));
}

/*
 * NSS nsmap management.
 */
void
_nsdbtaddsrc(ns_dbt *dbt, const ns_src *src)
{
        const ns_mod    *modp;

        dbt->srclist = vector_append(src, dbt->srclist, &dbt->srclistsize,
            sizeof(*src));
        modp = vector_search(&src->name, _nsmod, _nsmodsize, sizeof(*_nsmod),
            string_compare);
        if (modp == NULL)
                nss_load_module(src->name, NULL);
}


#ifdef _NSS_DEBUG
void
_nsdbtdump(const ns_dbt *dbt)
{
        int i;

        printf("%s (%d source%s):", dbt->name, dbt->srclistsize,
            dbt->srclistsize == 1 ? "" : "s");
        for (i = 0; i < (int)dbt->srclistsize; i++) {
                printf(" %s", dbt->srclist[i].name);
                if (!(dbt->srclist[i].flags &
                    (NS_UNAVAIL|NS_NOTFOUND|NS_TRYAGAIN)) &&
                    (dbt->srclist[i].flags & NS_SUCCESS))
                        continue;
                printf(" [");
                if (!(dbt->srclist[i].flags & NS_SUCCESS))
                        printf(" SUCCESS=continue");
                if (dbt->srclist[i].flags & NS_UNAVAIL)
                        printf(" UNAVAIL=return");
                if (dbt->srclist[i].flags & NS_NOTFOUND)
                        printf(" NOTFOUND=return");
                if (dbt->srclist[i].flags & NS_TRYAGAIN)
                        printf(" TRYAGAIN=return");
                printf(" ]");
        }
        printf("\n");
}
#endif


/*
 * The first time nsdispatch is called (during a process's lifetime,
 * or after nsswitch.conf has been updated), nss_configure will
 * prepare global data needed by NSS.
 */
static int
nss_configure(void)
{
        static time_t    confmod;
#ifndef NS_REREAD_CONF
        static int       already_initialized = 0;
#endif
        struct stat      statbuf;
        int              result, isthreaded;
        const char      *path;
#ifdef NS_CACHING
        void            *handle;
#endif

        result = 0;
        isthreaded = __isthreaded;
#if defined(_NSS_DEBUG) && defined(_NSS_SHOOT_FOOT)
        /* NOTE WELL:  THIS IS A SECURITY HOLE. This must only be built
         * for debugging purposes and MUST NEVER be used in production.
         */
        path = getenv("NSSWITCH_CONF");
        if (path == NULL)
#endif
                path = _PATH_NS_CONF;
#ifndef NS_REREAD_CONF
        /*
         * Define NS_REREAD_CONF to have nsswitch notice changes
         * to nsswitch.conf(5) during runtime.  This involves calling
         * stat(2) every time, which can result in performance hit.
         */
        if (already_initialized)
                return (0);
        already_initialized = 1;
#endif /* NS_REREAD_CONF */
        if (stat(path, &statbuf) != 0)
                return (0);
        if (statbuf.st_mtime <= confmod)
                return (0);
        if (isthreaded) {
                (void)_pthread_rwlock_unlock(&nss_lock);
                result = _pthread_rwlock_wrlock(&nss_lock);
                if (result != 0)
                        return (result);
                if (stat(path, &statbuf) != 0)
                        goto fin;
                if (statbuf.st_mtime <= confmod)
                        goto fin;
        }
        _nsyyin = fopen(path, "re");
        if (_nsyyin == NULL)
                goto fin;
        VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
            (vector_free_elem)ns_dbt_free);
        VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
            (vector_free_elem)ns_mod_free);
        if (confmod == 0)
                (void)atexit(nss_atexit);
        nss_load_builtin_modules();
        _nsyyparse();
        (void)fclose(_nsyyin);
        vector_sort(_nsmap, _nsmapsize, sizeof(*_nsmap), string_compare);
        confmod = statbuf.st_mtime;

#ifdef NS_CACHING
        handle = libc_dlopen(NULL, RTLD_LAZY | RTLD_GLOBAL);
        if (handle != NULL) {
                nss_cache_cycle_prevention_func = dlsym(handle,
                    "_nss_cache_cycle_prevention_function");
                dlclose(handle);
        }
#endif
fin:
        if (isthreaded) {
                (void)_pthread_rwlock_unlock(&nss_lock);
                if (result == 0)
                        result = _pthread_rwlock_rdlock(&nss_lock);
        }
        return (result);
}


void
_nsdbtput(const ns_dbt *dbt)
{
        unsigned int     i;
        ns_dbt          *p;

        for (i = 0; i < _nsmapsize; i++) {
                p = vector_ref(i, _nsmap, _nsmapsize, sizeof(*_nsmap));
                if (string_compare(&dbt->name, &p->name) == 0) {
                        /* overwrite existing entry */
                        if (p->srclist != NULL)
                                ns_src_free(&p->srclist, p->srclistsize);
                        memmove(p, dbt, sizeof(*dbt));
                        return;
                }
        }
        _nsmap = vector_append(dbt, _nsmap, &_nsmapsize, sizeof(*_nsmap));
}


static void
ns_dbt_free(ns_dbt *dbt)
{
        ns_src_free(&dbt->srclist, dbt->srclistsize);
        if (dbt->name)
                free((void *)dbt->name);
}


static void
ns_src_free(ns_src **src, int srclistsize)
{
        int     i;

        for (i = 0; i < srclistsize; i++)
                if ((*src)[i].name != NULL)
                        /* This one was allocated by nslexer. You'll just
                         * have to trust me.
                         */
                        free((void *)((*src)[i].name));
        free(*src);
        *src = NULL;
}



/*
 * NSS module management.
 */
/* The built-in NSS modules are all loaded at once. */
#define NSS_BACKEND(name, reg) \
ns_mtab *reg(unsigned int *, nss_module_unregister_fn *);
#include "nss_backends.h"
#undef NSS_BACKEND

static void
nss_load_builtin_modules(void)
{
#define NSS_BACKEND(name, reg) nss_load_module(#name, reg);
#include "nss_backends.h"
#undef NSS_BACKEND
}


/* Load a built-in or dynamically linked module.  If the `reg_fn'
 * argument is non-NULL, assume a built-in module and use reg_fn to
 * register it.  Otherwise, search for a dynamic NSS module.
 */
static void
nss_load_module(const char *source, nss_module_register_fn reg_fn)
{
        char             buf[PATH_MAX];
        ns_mod           mod;
        nss_module_register_fn fn;

        memset(&mod, 0, sizeof(mod));
        mod.name = strdup(source);
        if (mod.name == NULL) {
                nss_log_simple(LOG_ERR, "memory allocation failure");
                return;
        }
        if (reg_fn != NULL) {
                /* The placeholder is required, as a NULL handle
                 * represents an invalid module.
                 */
                mod.handle = nss_builtin_handle;
                fn = reg_fn;
        } else if (!is_dynamic()) {
                goto fin;
        } else if (strcmp(source, NSSRC_CACHE) == 0 ||
            strcmp(source, NSSRC_COMPAT) == 0 ||
            strcmp(source, NSSRC_DB) == 0 ||
            strcmp(source, NSSRC_DNS) == 0 ||
            strcmp(source, NSSRC_FILES) == 0 ||
            strcmp(source, NSSRC_NIS) == 0) {
                /*
                 * Avoid calling dlopen(3) for built-in modules.
                 */
                goto fin;
        } else {
                if (snprintf(buf, sizeof(buf), "nss_%s.so.%d", mod.name,
                    NSS_MODULE_INTERFACE_VERSION) >= (int)sizeof(buf))
                        goto fin;
                mod.handle = libc_dlopen(buf, RTLD_LOCAL|RTLD_LAZY);
                if (mod.handle == NULL) {
#ifdef _NSS_DEBUG
                        /* This gets pretty annoying since the built-in
                         * sources aren't modules yet.
                         */
                        nss_log(LOG_DEBUG, "%s, %s", mod.name, dlerror());
#endif
                        goto fin;
                }
                fn = (nss_module_register_fn)dlfunc(mod.handle,
                    "nss_module_register");
                if (fn == NULL) {
                        (void)dlclose(mod.handle);
                        mod.handle = NULL;
                        nss_log(LOG_ERR, "%s, %s", mod.name, dlerror());
                        goto fin;
                }
        }
        mod.mtab = fn(mod.name, &mod.mtabsize, &mod.unregister);
        if (mod.mtab == NULL || mod.mtabsize == 0) {
                if (mod.handle != nss_builtin_handle)
                        (void)dlclose(mod.handle);
                mod.handle = NULL;
                nss_log(LOG_ERR, "%s, registration failed", mod.name);
                goto fin;
        }
        if (mod.mtabsize > 1)
                qsort(mod.mtab, mod.mtabsize, sizeof(mod.mtab[0]),
                    mtab_compare);
fin:
        _nsmod = vector_append(&mod, _nsmod, &_nsmodsize, sizeof(*_nsmod));
        vector_sort(_nsmod, _nsmodsize, sizeof(*_nsmod), string_compare);
}

static int exiting = 0;

static void
ns_mod_free(ns_mod *mod)
{

        free(mod->name);
        if (mod->handle == NULL)
                return;
        if (mod->unregister != NULL)
                mod->unregister(mod->mtab, mod->mtabsize);
        if (mod->handle != nss_builtin_handle && !exiting)
                (void)dlclose(mod->handle);
}

/*
 * Cleanup
 */
static void
nss_atexit(void)
{
        int isthreaded;

        exiting = 1;
        isthreaded = __isthreaded;
        if (isthreaded)
                (void)_pthread_rwlock_wrlock(&nss_lock);
        VECTOR_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
            (vector_free_elem)ns_dbt_free);
        VECTOR_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
            (vector_free_elem)ns_mod_free);
        if (isthreaded)
                (void)_pthread_rwlock_unlock(&nss_lock);
}

/*
 * Finally, the actual implementation.
 */
static nss_method
nss_method_lookup(const char *source, const char *database,
    const char *method, const ns_dtab disp_tab[], void **mdata)
{
        ns_mod  *mod;
        ns_mtab *match, key;
        int      i;

        if (disp_tab != NULL)
                for (i = 0; disp_tab[i].src != NULL; i++)
                        if (strcasecmp(source, disp_tab[i].src) == 0) {
                                *mdata = disp_tab[i].mdata;
                                return (disp_tab[i].method);
                        }
        mod = vector_search(&source, _nsmod, _nsmodsize, sizeof(*_nsmod),
            string_compare);
        if (mod != NULL && mod->handle != NULL) {
                key.database = database;
                key.name = method;
                match = bsearch(&key, mod->mtab, mod->mtabsize,
                    sizeof(mod->mtab[0]), mtab_compare);
                if (match != NULL) {
                        *mdata = match->mdata;
                        return (match->method);
                }
        }

        *mdata = NULL;
        return (NULL);
}

static void
fb_endstate(void *p)
{
        free(p);
}

__weak_reference(_nsdispatch, nsdispatch);

int
_nsdispatch(void *retval, const ns_dtab disp_tab[], const char *database,
            const char *method_name, const ns_src defaults[], ...)
{
        va_list          ap;
        const ns_dbt    *dbt;
        const ns_src    *srclist;
        nss_method       method, fb_method;
        void            *mdata;
        int              isthreaded, serrno, i, result, srclistsize;
        struct fb_state *st;
        int              saved_depth;

#ifdef NS_CACHING
        nss_cache_data   cache_data;
        nss_cache_data  *cache_data_p;
        int              cache_flag;
#endif
        
        dbt = NULL;
        fb_method = NULL;

        isthreaded = __isthreaded;
        serrno = errno;
        if (isthreaded) {
                result = _pthread_rwlock_rdlock(&nss_lock);
                if (result != 0) {
                        result = NS_UNAVAIL;
                        goto fin;
                }
        }

        result = fb_getstate(&st);
        if (result != 0) {
                result = NS_UNAVAIL;
                goto fin;
        }

        result = nss_configure();
        if (result != 0) {
                result = NS_UNAVAIL;
                goto fin;
        }
        ++st->dispatch_depth;
        if (st->dispatch_depth > st->fallback_depth) {
                dbt = vector_search(&database, _nsmap, _nsmapsize, sizeof(*_nsmap),
                    string_compare);
                fb_method = nss_method_lookup(NSSRC_FALLBACK, database,
                    method_name, disp_tab, &mdata);
        }

        if (dbt != NULL) {
                srclist = dbt->srclist;
                srclistsize = dbt->srclistsize;
        } else {
                srclist = defaults;
                srclistsize = 0;
                while (srclist[srclistsize].name != NULL)
                        srclistsize++;
        }

#ifdef NS_CACHING
        cache_data_p = NULL;
        cache_flag = 0;
#endif
        for (i = 0; i < srclistsize; i++) {
                result = NS_NOTFOUND;
                method = nss_method_lookup(srclist[i].name, database,
                    method_name, disp_tab, &mdata);

                if (method != NULL) {
#ifdef NS_CACHING
                        if (strcmp(srclist[i].name, NSSRC_CACHE) == 0 &&
                            nss_cache_cycle_prevention_func == NULL) {
#ifdef NS_STRICT_LIBC_EID_CHECKING
                                if (issetugid() != 0)
                                        continue;
#endif
                                cache_flag = 1;

                                memset(&cache_data, 0, sizeof(nss_cache_data));
                                cache_data.info = (nss_cache_info const *)mdata;
                                cache_data_p = &cache_data;

                                va_start(ap, defaults);
                                if (cache_data.info->id_func != NULL)
                                        result = __nss_common_cache_read(retval,
                                            cache_data_p, ap);
                                else if (cache_data.info->marshal_func != NULL)
                                        result = __nss_mp_cache_read(retval,
                                            cache_data_p, ap);
                                else
                                        result = __nss_mp_cache_end(retval,
                                            cache_data_p, ap);
                                va_end(ap);
                        } else {
                                cache_flag = 0;
                                errno = 0;
                                va_start(ap, defaults);
                                result = method(retval, mdata, ap);
                                va_end(ap);
                        }
#else /* NS_CACHING */
                        errno = 0;
                        va_start(ap, defaults);
                        result = method(retval, mdata, ap);
                        va_end(ap);
#endif /* NS_CACHING */

                        if (result & (srclist[i].flags))
                                break;
                } else {
                        if (fb_method != NULL) {
                                saved_depth = st->fallback_depth;
                                st->fallback_depth = st->dispatch_depth + 1;
                                va_start(ap, defaults);
                                result = fb_method(retval,
                                    (void *)srclist[i].name, ap);
                                va_end(ap);
                                st->fallback_depth = saved_depth;
                        } else
                                nss_log(LOG_DEBUG, "%s, %s, %s, not found, "
                                    "and no fallback provided",
                                    srclist[i].name, database, method_name);
                }
        }

#ifdef NS_CACHING
        if (cache_data_p != NULL &&
            (result & (NS_NOTFOUND | NS_SUCCESS)) && cache_flag == 0) {
                va_start(ap, defaults);
                if (result == NS_SUCCESS) {
                        if (cache_data.info->id_func != NULL)
                                __nss_common_cache_write(retval, cache_data_p,
                                    ap);
                        else if (cache_data.info->marshal_func != NULL)
                                __nss_mp_cache_write(retval, cache_data_p, ap);
                } else if (result == NS_NOTFOUND) {
                        if (cache_data.info->id_func == NULL) {
                                if (cache_data.info->marshal_func != NULL)
                                        __nss_mp_cache_write_submit(retval,
                                            cache_data_p, ap);
                        } else
                                __nss_common_cache_write_negative(cache_data_p);
                }
                va_end(ap);
        }
#endif /* NS_CACHING */

        if (isthreaded)
                (void)_pthread_rwlock_unlock(&nss_lock);
        --st->dispatch_depth;
fin:
        errno = serrno;
        return (result);
}