/** BEGIN COPYRIGHT BLOCK
 * Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
 * Copyright (C) 2005 Red Hat, Inc.
 * All rights reserved.
 *
 * License: GPL (version 3 or any later version).
 * See LICENSE for details.
 * END COPYRIGHT BLOCK **/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

/* attrsyntax.c */

#include "slap.h"
#include <plhash.h>

/*
 * Note: if both the oid2asi and name2asi locks are acquired at the
 * same time, the old2asi one should be acquired first,
 */

/*
 * This hashtable maps the oid to the struct asyntaxinfo for that oid.
 */
static PLHashTable *oid2asi = NULL;
/* read/write lock to protect table */
static Slapi_RWLock *oid2asi_lock = NULL;
static PLHashTable *internalasi = NULL;

/* global attribute linked list */
static asyntaxinfo *global_at = NULL;

/*
 * This hashtable maps the name or alias of the attribute to the
 * syntax info structure for that attribute.  An attribute type has as
 * many entries in the name2asi table as it has names and aliases, but
 * all entries point to the same struct asyntaxinfo.
 */
static PLHashTable *name2asi = NULL;
/* read/write lock to protect table */
static Slapi_RWLock *name2asi_lock = NULL;

/*
 * For the schema reload task, we need to use separate temporary hashtables & linked lists
 */
static PLHashTable *oid2asi_tmp = NULL;
static PLHashTable *name2asi_tmp = NULL;
static asyntaxinfo *global_at_tmp = NULL;

static int asi_locking = 1;
#define AS_LOCK_READ(l)         \
    if (asi_locking) {          \
        slapi_rwlock_rdlock(l); \
    }
#define AS_LOCK_WRITE(l)        \
    if (asi_locking) {          \
        slapi_rwlock_wrlock(l); \
    }
#define AS_UNLOCK_READ(l)       \
    if (asi_locking) {          \
        slapi_rwlock_unlock(l); \
    }
#define AS_UNLOCK_WRITE(l)      \
    if (asi_locking) {          \
        slapi_rwlock_unlock(l); \
    }


static struct asyntaxinfo *default_asi = NULL;

static void *attr_syntax_get_plugin_by_name_with_default(const char *type);
static void attr_syntax_delete_no_lock(struct asyntaxinfo *asip,
                                       PRBool remove_from_oid_table,
                                       PRUint32 schema_flags);
static struct asyntaxinfo *attr_syntax_get_by_oid_locking_optional(const char *oid, PRBool use_lock, PRUint32 schema_flags);
static void attr_syntax_insert(struct asyntaxinfo *asip);
static void attr_syntax_insert_tmp(struct asyntaxinfo *asip);
static void attr_syntax_remove(struct asyntaxinfo *asip);

#ifdef ATTR_LDAP_DEBUG
static void attr_syntax_print(void);
#endif
static int attr_syntax_init(void);

struct asyntaxinfo *
attr_syntax_get_global_at()
{
    return global_at;
}

void
attr_syntax_read_lock(void)
{
    if (0 != attr_syntax_init()) {
        PR_ASSERT(0);
        return;
    }

    AS_LOCK_READ(oid2asi_lock);
    AS_LOCK_READ(name2asi_lock);
}

void
attr_syntax_write_lock(void)
{
    if (0 != attr_syntax_init()) {
        PR_ASSERT(0);
        return;
    }

    AS_LOCK_WRITE(oid2asi_lock);
    AS_LOCK_WRITE(name2asi_lock);
}

void
attr_syntax_unlock_read(void)
{
    AS_UNLOCK_READ(name2asi_lock);
    AS_UNLOCK_READ(oid2asi_lock);
}

void
attr_syntax_unlock_write(void)
{
    AS_UNLOCK_WRITE(name2asi_lock);
    AS_UNLOCK_WRITE(oid2asi_lock);
}

void
attr_syntax_free(struct asyntaxinfo *a)
{
    if (!a) {
        return;
    }
    cool_charray_free(a->asi_aliases);
    slapi_ch_free_string(&a->asi_name);
    slapi_ch_free_string(&a->asi_desc);
    slapi_ch_free_string(&a->asi_oid);
    slapi_ch_free_string(&a->asi_superior);
    slapi_ch_free_string(&a->asi_mr_equality);
    slapi_ch_free_string(&a->asi_mr_ordering);
    slapi_ch_free_string(&a->asi_mr_substring);
    slapi_ch_free_string(&a->asi_syntax_oid);
    schema_free_extensions(a->asi_extensions);
    slapi_ch_free((void **)&a);
}

static struct asyntaxinfo *
attr_syntax_new(void)
{
    return (struct asyntaxinfo *)slapi_ch_calloc(1, sizeof(struct asyntaxinfo));
}

/*
 * Given an OID, return the syntax info.  If there is more than one
 * attribute syntax with the same OID (i.e. aliases), the first one
 * will be returned.  This is usually the "canonical" one, but it may
 * not be.
 *
 * Note: once the caller is finished using it, the structure returned must
 * be returned by calling to attr_syntax_return().
 */
struct asyntaxinfo *
attr_syntax_get_by_oid(const char *oid, PRUint32 schema_flags)
{
    return attr_syntax_get_by_oid_locking_optional(oid, PR_TRUE, schema_flags);
}


/*
 * A version of attr_syntax_get_by_oid() that allows you to bypass using
 * a lock to access the global oid hash table.
 *
 * Note: once the caller is finished using it, the structure must be
 * returned by calling attr_syntax_return_locking_optional() with the
 * same use_lock parameter.
 */
static struct asyntaxinfo *
attr_syntax_get_by_oid_locking_optional(const char *oid, PRBool use_lock, PRUint32 schema_flags)
{
    struct asyntaxinfo *asi = 0;
    PLHashTable *ht = oid2asi;
    int using_tmp_ht = 0;

    if (schema_flags & DSE_SCHEMA_LOCKED) {
        ht = oid2asi_tmp;
        using_tmp_ht = 1;
        use_lock = 0;
    }
    if (ht) {
        if (use_lock) {
            AS_LOCK_READ(oid2asi_lock);
        }
        if (!using_tmp_ht) {
            /*
             * The oid2asi pointer could have been rewritten by the schema_reload task
             * while waiting on the lock, so grab it again.
             */
            ht = oid2asi;
        }
        asi = (struct asyntaxinfo *)PL_HashTableLookup_const(ht, oid);
        if (asi) {
            slapi_atomic_incr_64(&(asi->asi_refcnt), __ATOMIC_RELEASE);
        }
        if (use_lock) {
            AS_UNLOCK_READ(oid2asi_lock);
        }
    }

    return asi;
}

/*
 * Add the syntax info pointer to the look-up-by-oid table.
 * The lock parameter is used by the initialization code.  Normally, we want
 * to acquire a write lock before we modify the table, but during
 * initialization, we are running in single threaded mode, so we don't have
 * to worry about resource contention.
 */
static void
attr_syntax_add_by_oid(const char *oid, struct asyntaxinfo *a, PRUint32 schema_flags, int lock)
{
    if (0 != attr_syntax_init())
        return;

    if (schema_flags & DSE_SCHEMA_LOCKED) {
        PL_HashTableAdd(oid2asi_tmp, oid, a);
    } else {
        if (lock) {
            AS_LOCK_WRITE(oid2asi_lock);
        }

        PL_HashTableAdd(oid2asi, oid, a);

        if (lock) {
            AS_UNLOCK_WRITE(oid2asi_lock);
        }
    }
}

/*
 * Return the syntax info given an attribute name.  The name may be the
 * "canonical" name, an alias, or an OID.  The given name need not be
 * normalized since the look up is done case insensitively.
 *
 * Note: once the caller is finished using it, the structure returned must
 * be returned by calling to attr_syntax_return().
 */
struct asyntaxinfo *
attr_syntax_get_by_name(const char *name, PRUint32 schema_flags)
{
    return attr_syntax_get_by_name_locking_optional(name, PR_TRUE, schema_flags);
}

struct asyntaxinfo *
attr_syntax_get_by_name_with_default(const char *name)
{
    struct asyntaxinfo *asi = NULL;
    asi = attr_syntax_get_by_name_locking_optional(name, PR_TRUE, 0);
    if (asi == NULL)
        asi = attr_syntax_get_by_name(ATTR_WITH_OCTETSTRING_SYNTAX, 0);
    if (asi == NULL)
        asi = default_asi;
    return asi;
}

/*
 * A version of attr_syntax_get_by_name() that allows you to bypass using
 * a lock around the global name hashtable.
 *
 * Note: once the caller is finished using it, the structure must be
 * returned by calling attr_syntax_return_locking_optional() with the
 * same use_lock parameter.
 */
struct asyntaxinfo *
attr_syntax_get_by_name_locking_optional(const char *name, PRBool use_lock, PRUint32 schema_flags)
{
    struct asyntaxinfo *asi = 0;
    PLHashTable *ht = name2asi;
    int using_tmp_ht = 0;

    if (schema_flags & DSE_SCHEMA_LOCKED) {
        ht = name2asi_tmp;
        using_tmp_ht = 1;
        use_lock = 0;
    }
    if (ht) {
        if (use_lock) {
            AS_LOCK_READ(name2asi_lock);
        }
        if (!using_tmp_ht) {
            /*
             * The name2asi pointer could have been rewritten by the schema_reload task
             * while waiting on the lock, so grab it again.
             */
            ht = name2asi;
        }
        asi = (struct asyntaxinfo *)PL_HashTableLookup_const(ht, name);
        if (NULL != asi) {
            slapi_atomic_incr_64(&(asi->asi_refcnt), __ATOMIC_RELEASE);
        }
        if (use_lock) {
            AS_UNLOCK_READ(name2asi_lock);
        }
    }
    if (!asi) /* given name may be an OID */
        asi = attr_syntax_get_by_oid_locking_optional(name, use_lock, schema_flags);

    return asi;
}

/*
 * This assumes you have taken the attr_syntax read lock. Assert an attribute type
 * exists by name. 0 is false, 1 is true.
 *
 * The main reason to use this over attr_syntax_get_by_name_locking_optional is to
 * avoid the reference count increment/decrement cycle when we only need a boolean
 * of existance, rather than retriving the reference to the attribute itself.
 *
 * But we do need to strip subtypes
 */
int32_t
attr_syntax_exist_by_name_nolock(char *name) {
    struct asyntaxinfo *asi = NULL;
    char *check_name = NULL;
    char *p = NULL;
    int free_attr = 0;

    /* Ignore any attribute subtypes. */
    if ((p = strchr(name, ';'))) {
        int check_len = p - name + 1;

        check_name = (char *)slapi_ch_malloc(check_len);
        PR_snprintf(check_name, check_len, "%s", name);
        free_attr = 1;
    } else {
        check_name = name;
    }

    asi = (struct asyntaxinfo *)PL_HashTableLookup_const(name2asi, check_name);

    if (free_attr) {
        slapi_ch_free_string(&check_name);
    }

    if (asi != NULL) {
        return 1;
    }
    return 0;
}


/*
 * Give up a reference to an asi.
 * If the asi has been marked for delete, free it.  This would be a bit
 * easier if we could upgrade a read lock to a write one... but NSPR does
 * not support that paradigm.
 */
void
attr_syntax_return(struct asyntaxinfo *asi)
{
    attr_syntax_return_locking_optional(asi, PR_TRUE);
}

void
attr_syntax_return_locking_optional(struct asyntaxinfo *asi, PRBool use_lock)
{
    int locked = 0;
    if (use_lock) {
        AS_LOCK_READ(name2asi_lock);
        locked = 1;
    }
    if (NULL != asi) {
        PRBool delete_it = PR_FALSE;
        if (0 == slapi_atomic_decr_64(&(asi->asi_refcnt), __ATOMIC_ACQ_REL)) {
            delete_it = asi->asi_marked_for_delete;
        }

        if (delete_it) {
            if (asi->asi_marked_for_delete) { /* one final check */
                if (use_lock) {
                    AS_UNLOCK_READ(name2asi_lock);
                    AS_LOCK_WRITE(name2asi_lock);
                }
                /* ref count is 0 and it's flagged for
                 * deletion, so it's safe to free now */
                attr_syntax_remove(asi);
                attr_syntax_free(asi);
                if (use_lock) {
                    AS_UNLOCK_WRITE(name2asi_lock);
                    locked = 0;
                }
            }
        }
    }
    if (locked) {
        AS_UNLOCK_READ(name2asi_lock);
    }
}

/*
 * Add the syntax info to the look-up-by-name table.  The asi_name and
 * elements of the asi_aliasses field of the syntax info are the keys.
 * These need not be normalized since the look up table is case insensitive.
 * The lock parameter is used by the initialization code.  Normally, we want
 * to acquire a write lock before we modify the table, but during
 * initialization, we are running in single threaded mode, so we don't have
 * to worry about resource contention.
 */
static void
attr_syntax_add_by_name(struct asyntaxinfo *a, PRUint32 schema_flags, int lock)
{
    if (0 != attr_syntax_init())
        return;

    if (schema_flags & DSE_SCHEMA_LOCKED) {
        /* insert the attr into the temp global linked list */
        attr_syntax_insert_tmp(a);

        PL_HashTableAdd(name2asi_tmp, a->asi_name, a);
        if (a->asi_aliases != NULL) {
            int i;

            for (i = 0; a->asi_aliases[i] != NULL; ++i) {
                PL_HashTableAdd(name2asi_tmp, a->asi_aliases[i], a);
            }
        }
    } else {
        if (lock) {
            AS_LOCK_WRITE(name2asi_lock);
        }
        /* insert the attr into the global linked list */
        attr_syntax_insert(a);

        PL_HashTableAdd(name2asi, a->asi_name, a);
        if (a->asi_aliases != NULL) {
            int i;

            for (i = 0; a->asi_aliases[i] != NULL; ++i) {
                PL_HashTableAdd(name2asi, a->asi_aliases[i], a);
            }
        }

        if (lock) {
            AS_UNLOCK_WRITE(name2asi_lock);
        }
    }
}


/*
 * Delete the attribute syntax and all entries corresponding to aliases
 * and oids.
 */
void
attr_syntax_delete(struct asyntaxinfo *asi, PRUint32 schema_flags)
{
    PR_ASSERT(asi);

    if (oid2asi && name2asi) {
        AS_LOCK_WRITE(oid2asi_lock);
        AS_LOCK_WRITE(name2asi_lock);

        attr_syntax_delete_no_lock(asi, PR_TRUE, schema_flags);

        AS_UNLOCK_WRITE(name2asi_lock);
        AS_UNLOCK_WRITE(oid2asi_lock);
    }
}


/*
 * Dispose of a node.  The caller is responsible for locking.  See
 * attr_syntax_delete() for an example.
 */
static void
attr_syntax_delete_no_lock(struct asyntaxinfo *asi,
                           PRBool remove_from_oidtable,
                           PRUint32 schema_flags)
{
    PLHashTable *ht = NULL;
    int using_tmp_ht = 0;
    int i;

    if (schema_flags & DSE_SCHEMA_LOCKED) {
        using_tmp_ht = 1;
    }
    if (oid2asi && remove_from_oidtable) {
        if (using_tmp_ht) {
            ht = oid2asi_tmp;
        } else {
            ht = oid2asi;
        }
        PL_HashTableRemove(ht, asi->asi_oid);
    }

    if (name2asi) {
        if (using_tmp_ht) {
            ht = name2asi_tmp;
        } else {
            ht = name2asi;
        }
        PL_HashTableRemove(ht, asi->asi_name);
        if (asi->asi_aliases != NULL) {
            for (i = 0; asi->asi_aliases[i] != NULL; ++i) {
                PL_HashTableRemove(ht, asi->asi_aliases[i]);
            }
        }
        if (slapi_atomic_load_64(&(asi->asi_refcnt), __ATOMIC_ACQUIRE) > 0) {
            asi->asi_marked_for_delete = PR_TRUE;
        } else {
            /* This is ok, but the correct thing is to call delete first,
             * then to call return.  The last return will then take care of
             * the free.  The only way this free would happen here is if
             * you return the syntax before calling delete. */
            attr_syntax_remove(asi);
            attr_syntax_free(asi);
        }
    }
}


/*
 * Look up the attribute type in the syntaxes and return a copy of the
 * normalised attribute type. If it's not there then return a normalised
 * copy of what the caller gave us.
 *
 * Warning: The caller must free the returned string.
 */
char *
slapi_attr_syntax_normalize(const char *s)
{
    struct asyntaxinfo *asi = NULL;
    char *r = NULL;

    if ((asi = attr_syntax_get_by_name(s, 0)) != NULL) {
        r = slapi_ch_strdup(asi->asi_name);
        attr_syntax_return(asi);
    }
    if (NULL == asi) {
        slapi_ch_free_string(&r);
        r = attr_syntax_normalize_no_lookup(s);
    }
    return r;
}

/*
 * flags:
 * 0 -- same as slapi_attr_syntax_normalize
 * ATTR_SYNTAX_NORM_ORIG_ATTR -- In addition to slapi_attr_syntax_normalize,
 *                               a space and following characters are removed
 *                               from the given string 's'.
 */
char *
slapi_attr_syntax_normalize_ext(char *s, int flags)
{
    struct asyntaxinfo *asi = NULL;
    char *r = NULL;

    if ((asi = attr_syntax_get_by_name(s, flags)) != NULL) {
        r = slapi_ch_strdup(asi->asi_name);
        attr_syntax_return(asi);
    }
    if (NULL == asi) {
        slapi_ch_free_string(&r);
        r = attr_syntax_normalize_no_lookup_ext(s, flags);
    }
    return r;
}

/*
 * attr_syntax_exists: return 1 if attr_name exists, 0 otherwise
 *
 */
int
attr_syntax_exists(const char *attr_name)
{
    struct asyntaxinfo *asi;
    char *check_attr_name = NULL;
    char *p = NULL;
    int free_attr = 0;

    /* Ignore any attribute subtypes. */
    if ((p = strchr(attr_name, ';'))) {
        int check_attr_len = p - attr_name + 1;

        check_attr_name = (char *)slapi_ch_malloc(check_attr_len);
        PR_snprintf(check_attr_name, check_attr_len, "%s", attr_name);
        free_attr = 1;
    } else {
        check_attr_name = (char *)attr_name;
    }

    asi = attr_syntax_get_by_name(check_attr_name, 0);
    attr_syntax_return(asi);

    if (free_attr) {
        slapi_ch_free_string(&check_attr_name);
    }

    if (asi != NULL) {
        return 1;
    }
    return 0;
}

static void default_dirstring_normalize_int(char *s, int trim_spaces);

static int
default_dirstring_filter_ava(struct berval *bvfilter __attribute__((unused)),
                             Slapi_Value **bvals __attribute__((unused)),
                             int ftype __attribute__((unused)),
                             Slapi_Value **retVal __attribute__((unused)))
{
    return (0);
}

static int
default_dirstring_values2keys(Slapi_PBlock *pb __attribute__((unused)),
                              Slapi_Value **bvals,
                              Slapi_Value ***ivals,
                              int ftype)
{
    int numbvals = 0;
    Slapi_Value **nbvals, **nbvlp;
    Slapi_Value **bvlp;
    char *c;

    if (NULL == ivals) {
        return 1;
    }
    *ivals = NULL;
    if (NULL == bvals) {
        return 1;
    }
    switch (ftype) {
    case LDAP_FILTER_EQUALITY:
        /* allocate a new array for the normalized values */
        for (bvlp = bvals; bvlp && *bvlp; bvlp++) {
            numbvals++;
        }
        nbvals = (Slapi_Value **)slapi_ch_calloc((numbvals + 1), sizeof(Slapi_Value *));

        for (bvlp = bvals, nbvlp = nbvals; bvlp && *bvlp; bvlp++, nbvlp++) {
            c = slapi_ch_strdup(slapi_value_get_string(*bvlp));
            default_dirstring_normalize_int(c, 1);
            *nbvlp = slapi_value_new_string_passin(c);
            c = NULL;
        }
        *ivals = nbvals;
        break;

    case LDAP_FILTER_APPROX:
    case LDAP_FILTER_SUBSTRINGS:
    default:
        /* default plugin only handles equality so far */
        slapi_log_err(SLAPI_LOG_ERR,
                      "default_dirstring_values2keys", "Unsupported ftype 0x%x\n",
                      ftype);
        break;
    }
    return (0);
}

static int
default_dirstring_assertion2keys_ava(Slapi_PBlock *pb __attribute__((unused)),
                                     Slapi_Value *val __attribute__((unused)),
                                     Slapi_Value ***ivals __attribute__((unused)),
                                     int ftype __attribute__((unused)))
{
    return (0);
}

static int
default_dirstring_cmp(struct berval *v1 __attribute__((unused)),
                      struct berval *v2 __attribute__((unused)),
                      int normalize __attribute__((unused)))
{
    return (0);
}

static void
default_dirstring_normalize(Slapi_PBlock *pb __attribute__((unused)),
                            char *s,
                            int trim_spaces,
                            char **alt __attribute__((unused)))
{
    default_dirstring_normalize_int(s, trim_spaces);
}

static void
default_dirstring_normalize_int(char *s, int trim_spaces)
{
    char *head = s;
    char *d;
    int prevspace, curspace;

    if (NULL == s) {
        return;
    }
    d = s;
    if (trim_spaces) {
        /* strip leading blanks */
        while (ldap_utf8isspace(s)) {
            LDAP_UTF8INC(s);
        }
    }

    /* handle value of all spaces - turn into single space */
    if (*s == '\0' && s != d) {
        *d++ = ' ';
        *d = '\0';
        return;
    }
    prevspace = 0;
    while (*s) {
        int ssz, dsz;
        curspace = ldap_utf8isspace(s);

        /* compress multiple blanks */
        if (prevspace && curspace) {
            LDAP_UTF8INC(s);
            continue;
        }
        prevspace = curspace;
        slapi_utf8ToLower((unsigned char *)s, (unsigned char *)d, &ssz, &dsz);
        s += ssz;
        d += dsz;
    }
    *d = '\0';
    /* strip trailing blanks */
    if (prevspace && trim_spaces) {
        char *nd;

        nd = ldap_utf8prev(d);
        while (nd && nd >= head && ldap_utf8isspace(nd)) {
            d = nd;
            nd = ldap_utf8prev(d);
            *d = '\0';
        }
    }
}

static struct slapdplugin *
attr_syntax_default_plugin(const char *nameoroid)
{

    struct slapdplugin *pi = NULL;
    /*
     * create a new plugin structure and
     * set the plugin function pointers.
     */
    pi = (struct slapdplugin *)slapi_ch_calloc(1, sizeof(struct slapdplugin));

    pi->plg_dn = slapi_ch_strdup("default plugin for directory string syntax");
    pi->plg_closed = 0;
    pi->plg_syntax_oid = slapi_ch_strdup(nameoroid);


    pi->plg_syntax_filter_ava = (IFP)default_dirstring_filter_ava;
    pi->plg_syntax_values2keys = (IFP)default_dirstring_values2keys;
    pi->plg_syntax_assertion2keys_ava = (IFP)default_dirstring_assertion2keys_ava;
    pi->plg_syntax_compare = (IFP)default_dirstring_cmp;
    pi->plg_syntax_normalize = (VFPV)default_dirstring_normalize;

    return (pi);
}
/* check syntax */

static void *
attr_syntax_get_plugin_by_name_with_default(const char *type)
{
    struct asyntaxinfo *asi;
    void *plugin = NULL;

    /*
     * first we look for this attribute type explictly
     */
    if ((asi = attr_syntax_get_by_name(type, 0)) == NULL) {
        /*
         * no syntax for this type... return Octet String
         * syntax.  we accomplish this by looking up a well known
         * attribute type that has that syntax.
         */
        asi = attr_syntax_get_by_name(ATTR_WITH_OCTETSTRING_SYNTAX, 0);
        if (asi == NULL)
            asi = default_asi;
    }
    if (NULL != asi) {
        plugin = asi->asi_plugin;
        attr_syntax_return(asi);
    }

    return (plugin);
}


static struct asyntaxinfo *
attr_syntax_dup(struct asyntaxinfo *a)
{
    struct asyntaxinfo *newas = attr_syntax_new();

    newas->asi_aliases = cool_charray_dup(a->asi_aliases);
    newas->asi_name = slapi_ch_strdup(a->asi_name);
    newas->asi_desc = slapi_ch_strdup(a->asi_desc);
    newas->asi_superior = slapi_ch_strdup(a->asi_superior);
    newas->asi_mr_equality = slapi_ch_strdup(a->asi_mr_equality);
    newas->asi_mr_ordering = slapi_ch_strdup(a->asi_mr_ordering);
    newas->asi_mr_substring = slapi_ch_strdup(a->asi_mr_substring);
    newas->asi_extensions = schema_copy_extensions(a->asi_extensions);
    newas->asi_plugin = a->asi_plugin;
    newas->asi_flags = a->asi_flags;
    newas->asi_oid = slapi_ch_strdup(a->asi_oid);
    newas->asi_syntaxlength = a->asi_syntaxlength;
    newas->asi_mr_eq_plugin = a->asi_mr_eq_plugin;
    newas->asi_mr_ord_plugin = a->asi_mr_ord_plugin;
    newas->asi_mr_sub_plugin = a->asi_mr_sub_plugin;
    newas->asi_syntax_oid = slapi_ch_strdup(a->asi_syntax_oid);
    newas->asi_next = NULL;
    newas->asi_prev = NULL;

    return (newas);
}

static void
attr_syntax_insert(struct asyntaxinfo *asip)
{
    /* Insert at top of list */
    asip->asi_prev = NULL;
    asip->asi_next = global_at;
    if (global_at) {
        global_at->asi_prev = asip;
        global_at = asip;
    } else {
        global_at = asip;
    }
}

static void
attr_syntax_insert_tmp(struct asyntaxinfo *asip)
{
    /* Insert at top of list */
    asip->asi_prev = NULL;
    asip->asi_next = global_at_tmp;
    if (global_at_tmp) {
        global_at_tmp->asi_prev = asip;
        global_at_tmp = asip;
    } else {
        global_at_tmp = asip;
    }
}

static void
attr_syntax_remove(struct asyntaxinfo *asip)
{
    struct asyntaxinfo *prev, *next;

    prev = asip->asi_prev;
    next = asip->asi_next;
    if (prev) {
        prev->asi_next = next;
        if (next) {
            next->asi_prev = prev;
        }
    } else {
        if (next) {
            next->asi_prev = NULL;
        }
        global_at = next;
    }
}

/*
 * Add a new attribute type to the schema.
 *
 * Returns an LDAP error code (LDAP_SUCCESS if all goes well).
 */
int
attr_syntax_add(struct asyntaxinfo *asip, PRUint32 schema_flags)
{
    int i, rc = LDAP_SUCCESS;
    int nolock = asip->asi_flags & SLAPI_ATTR_FLAG_NOLOCKING;
    struct asyntaxinfo *oldas_from_oid = NULL, *oldas_from_name = NULL;
    /* attr names may have subtypes in them, and we may not want this
       if strip_subtypes is true, the ; and anything after it in the
       attr name or alias will be stripped */
    /*int strip_subtypes = 1;*/

    /* make sure the oid is unique */
    if (NULL != (oldas_from_oid = attr_syntax_get_by_oid_locking_optional(
                     asip->asi_oid, !nolock, schema_flags))) {
        if (0 == (asip->asi_flags & SLAPI_ATTR_FLAG_OVERRIDE)) {
            /* failure - OID is in use; no override flag */
            rc = LDAP_TYPE_OR_VALUE_EXISTS;
            goto cleanup_and_return;
        }
    }
    /*
     * Make sure the primary name is unique OR, if override is allowed, that
     * the primary name and OID point to the same schema definition.
     */
    if (NULL != (oldas_from_name = attr_syntax_get_by_name_locking_optional(
                     asip->asi_name, !nolock, schema_flags))) {
        if (0 == (asip->asi_flags & SLAPI_ATTR_FLAG_OVERRIDE) || (oldas_from_oid != oldas_from_name)) {
            /* failure; no override flag OR OID and name don't match */
            rc = LDAP_TYPE_OR_VALUE_EXISTS;
            goto cleanup_and_return;
        }
        /* Flag for deletion.  We are going to override this attr */
        attr_syntax_delete(oldas_from_name, schema_flags);
    } else if (NULL != oldas_from_oid) {
        /* failure - OID is in use but name does not exist */
        rc = LDAP_TYPE_OR_VALUE_EXISTS;
        goto cleanup_and_return;
    }

    if (NULL != asip->asi_aliases) {
        /* make sure the aliases are unique */
        for (i = 0; asip->asi_aliases[i] != NULL; ++i) {
            struct asyntaxinfo *tmpasi;

            if (NULL != (tmpasi =
                             attr_syntax_get_by_name_locking_optional(
                                 asip->asi_aliases[i], !nolock, schema_flags))) {
                if (asip->asi_flags & SLAPI_ATTR_FLAG_OVERRIDE) {
                    /* Flag for tmpasi for deletion.  It will be free'd
                     * when attr_syntax_return is called. */
                    attr_syntax_delete(tmpasi, schema_flags);
                } else {
                    /* failure - one of the aliases is already in use */
                    rc = LDAP_TYPE_OR_VALUE_EXISTS;
                }

                attr_syntax_return_locking_optional(tmpasi, !nolock);
                if (LDAP_SUCCESS != rc) {
                    goto cleanup_and_return;
                }
            }
        }
    }

    /* the no lock flag is not worth keeping around */
    asip->asi_flags &= ~SLAPI_ATTR_FLAG_NOLOCKING;
    /* ditto for the override one */
    asip->asi_flags &= ~SLAPI_ATTR_FLAG_OVERRIDE;

    attr_syntax_add_by_oid(asip->asi_oid, asip, schema_flags, !nolock);
    attr_syntax_add_by_name(asip, schema_flags, !nolock);

cleanup_and_return:
    attr_syntax_return_locking_optional(oldas_from_oid, !nolock);
    attr_syntax_return_locking_optional(oldas_from_name, !nolock);
    return rc;
}

static int
attr_syntax_create_default(const char *name, const char *oid, const char *syntax, unsigned long extraflags)
{
    int rc = 0;
    char *names[2];
    unsigned long std_flags = SLAPI_ATTR_FLAG_STD_ATTR | SLAPI_ATTR_FLAG_OPATTR;

    names[0] = (char *)name;
    names[1] = NULL;

    if (default_asi)
        return (rc);

    rc = attr_syntax_create(oid, names,
                            "internal server defined attribute type",
                            NULL,             /* superior */
                            NULL, NULL, NULL, /* matching rules */
                            NULL, syntax,
                            SLAPI_SYNTAXLENGTH_NONE,
                            std_flags | extraflags,
                            &default_asi);
    if (rc == 0 && default_asi->asi_plugin == 0)
        default_asi->asi_plugin = attr_syntax_default_plugin(syntax);
    return (rc);
}

/*
 * Returns an LDAP result code.
 */
int
attr_syntax_create(
    const char *attr_oid,
    char *const *attr_names,
    const char *attr_desc,
    const char *attr_superior,
    const char *mr_equality,
    const char *mr_ordering,
    const char *mr_substring,
    schemaext *extensions,
    const char *attr_syntax,
    int syntaxlength,
    unsigned long flags,
    struct asyntaxinfo **asip)
{
    char *s;
    struct asyntaxinfo a = {0};
    int rc = LDAP_SUCCESS;

    /* XXXmcs: had to cast away const in many places below */
    *asip = NULL;
    a.asi_name = slapi_ch_strdup(attr_names[0]);
    if (NULL != attr_names[1]) {
        a.asi_aliases = (char **)&attr_names[1]; /* all but the zero'th element */
    }
    a.asi_desc = (char *)attr_desc;
    a.asi_oid = (char *)attr_oid;
    a.asi_superior = (char *)attr_superior;
    a.asi_mr_equality = (char *)mr_equality;
    a.asi_mr_ordering = (char *)mr_ordering;
    a.asi_mr_substring = (char *)mr_substring;
    a.asi_extensions = extensions;
    a.asi_plugin = plugin_syntax_find(attr_syntax);
    a.asi_syntax_oid = (char *)attr_syntax;
    a.asi_syntaxlength = syntaxlength;
    /* ideally, we would report an error and fail to start if there was some problem
       with the matching rule - but since this functionality is new, and we might
       cause havoc if lots of servers failed to start because of bogus schema, we
       just report an error here - at some point in the future, we should actually
       report an error and exit, or allow the user to control the behavior - for
       now, just log an error, and address each case
    */
    if (mr_equality && !slapi_matchingrule_is_compat(mr_equality, attr_syntax)) {
        slapi_log_err(SLAPI_LOG_ERR, "attr_syntax_create",
                      "Error: the EQUALITY matching rule [%s] is not compatible "
                      "with the syntax [%s] for the attribute [%s]\n",
                      mr_equality, attr_syntax, attr_names[0]);
#ifdef ENFORCE_MR_SYNTAX_COMPAT
        rc = LDAP_INAPPROPRIATE_MATCHING;
        goto done;
#endif /* ENFORCE_MR_SYNTAX_COMPAT */
    }
    a.asi_mr_eq_plugin = plugin_mr_find(mr_equality);
    if (mr_ordering && !slapi_matchingrule_is_compat(mr_ordering, attr_syntax)) {
        slapi_log_err(SLAPI_LOG_ERR, "attr_syntax_create",
                      "Error: the ORDERING matching rule [%s] is not compatible "
                      "with the syntax [%s] for the attribute [%s]\n",
                      mr_ordering, attr_syntax, attr_names[0]);
#ifdef ENFORCE_MR_SYNTAX_COMPAT
        rc = LDAP_INAPPROPRIATE_MATCHING;
        goto done;
#endif /* ENFORCE_MR_SYNTAX_COMPAT */
    }
    a.asi_mr_ord_plugin = plugin_mr_find(mr_ordering);
    if (mr_substring && !slapi_matchingrule_is_compat(mr_substring, attr_syntax)) {
        slapi_log_err(SLAPI_LOG_ERR, "attr_syntax_create",
                      "Error: the SUBSTR matching rule [%s] is not compatible "
                      "with the syntax [%s] for the attribute [%s]\n",
                      mr_substring, attr_syntax, attr_names[0]);
#ifdef ENFORCE_MR_SYNTAX_COMPAT
        rc = LDAP_INAPPROPRIATE_MATCHING;
        goto done;
#endif /* ENFORCE_MR_SYNTAX_COMPAT */
    }
    a.asi_mr_sub_plugin = plugin_mr_find(mr_substring);
    a.asi_flags = flags;

    /*
     * If the 'return exact case' option is on (the default), we store the
     * first name (the canonical one) unchanged so that attribute names are
     * returned exactly as they appear in the schema configuration files.
     * But if 'return exact case' has been turned off, we convert the name
     * to lowercase.  In Netscape Directory Server 4.x and earlier versions,
     * the default was to convert to lowercase.
     */
    if (!config_get_return_exact_case()) {
        for (s = a.asi_name; *s; ++s) {
            *s = TOLOWER(*s);
        }
    }

    *asip = attr_syntax_dup(&a);

#ifdef ENFORCE_MR_SYNTAX_COMPAT
done:
#endif /* ENFORCE_MR_SYNTAX_COMPAT */
    slapi_ch_free((void **)&a.asi_name);

    return rc;
}


/*
 * slapi_attr_type2plugin - return the plugin handling the attribute type
 * if type is unknown, we return the caseIgnoreString plugin used by the
 *     objectClass attribute type.
 */

int
slapi_attr_type2plugin(const char *type, void **pi)
{
    char buf[SLAPD_TYPICAL_ATTRIBUTE_NAME_MAX_LENGTH];
    char *tmp, *basetype;
    int rc;

    basetype = buf;
    if ((tmp = slapi_attr_basetype(type, buf, sizeof(buf))) != NULL) {
        basetype = tmp;
    }
    rc = -1;
    *pi = attr_syntax_get_plugin_by_name_with_default(basetype);
    if (NULL != *pi) {
        rc = 0;
    }
    slapi_ch_free_string(&tmp);

    return (rc);
}

/* deprecated -- not MT safe (pointer into asi is returned!) */
int
slapi_attr_get_oid(const Slapi_Attr *a, char **oid)
{
    struct asyntaxinfo *asi = attr_syntax_get_by_name(a->a_type, 0);
    if (asi) {
        *oid = asi->asi_oid;
        attr_syntax_return(asi);
        return (0);
    } else {
        *oid = NULL;
        return (-1);
    }
}


/* The caller must dispose of oid by calling slapi_ch_free(). */
int
slapi_attr_get_oid_copy(const Slapi_Attr *a, char **oidp)
{
    struct asyntaxinfo *asi = attr_syntax_get_by_name(a->a_type, 0);
    if (asi) {
        *oidp = slapi_ch_strdup(asi->asi_oid);
        attr_syntax_return(asi);
        return (0);
    } else {
        *oidp = NULL;
        return (-1);
    }
}

/* Returns the oid of the syntax of the Slapi_Attr that's passed in.
 * The caller must dispose of oid by calling slapi_ch_free_string(). */
int
slapi_attr_get_syntax_oid_copy(const Slapi_Attr *a, char **oidp)
{
    const char *oid;
    if (a && ((oid = attr_get_syntax_oid(a)))) {
        *oidp = slapi_ch_strdup(oid);
        return (0);
    } else {
        *oidp = NULL;
        return (-1);
    }
}

int
slapi_attr_is_dn_syntax_attr(Slapi_Attr *attr)
{
    const char *syntaxoid = NULL;
    int dn_syntax = 0; /* not DN, by default */

    if (attr && attr->a_flags & SLAPI_ATTR_FLAG_SYNTAX_IS_DN)
        /* it was checked before */
        return (1);

    if (attr && attr->a_plugin == NULL) {
        slapi_attr_init_syntax(attr);
    }
    if (attr && attr->a_plugin) { /* If not set, there is no way to get the info */
        if ((syntaxoid = attr_get_syntax_oid(attr))) {
            dn_syntax = ((0 == strcmp(syntaxoid, NAMEANDOPTIONALUID_SYNTAX_OID)) || (0 == strcmp(syntaxoid, DN_SYNTAX_OID)));
        }
        if (dn_syntax)
            attr->a_flags |= SLAPI_ATTR_FLAG_SYNTAX_IS_DN;
    }
    return dn_syntax;
}

int
slapi_attr_is_dn_syntax_type(char *type)
{
    const char *syntaxoid = NULL;
    int dn_syntax = 0; /* not DN, by default */
    struct asyntaxinfo *asi;

    asi = attr_syntax_get_by_name(type, 0);

    if (asi && asi->asi_plugin) { /* If not set, there is no way to get the info */
        if ((syntaxoid = asi->asi_plugin->plg_syntax_oid)) {
            dn_syntax = ((0 == strcmp(syntaxoid, NAMEANDOPTIONALUID_SYNTAX_OID)) || (0 == strcmp(syntaxoid, DN_SYNTAX_OID)));
        }
    }
    return dn_syntax;
}

#ifdef ATTR_LDAP_DEBUG

PRIntn
attr_syntax_printnode(PLHashEntry *he, PRIntn i, void *arg)
{
    char *alias = (char *)he->key;
    struct asyntaxinfo *a = (struct asyntaxinfo *)he->value;
    schemaext *ext = a->asi_extensions;

    printf("  name: %s\n", a->asi_name);
    printf("\t flags       : 0x%x\n", a->asi_flags);
    printf("\t alias       : %s\n", alias);
    printf("\t desc        : %s\n", a->asi_desc);
    printf("\t oid         : %s\n", a->asi_oid);
    printf("\t superior    : %s\n", a->asi_superior);
    printf("\t mr_equality : %s\n", a->asi_mr_equality);
    printf("\t mr_ordering : %s\n", a->asi_mr_ordering);
    printf("\t mr_substring: %s\n", a->asi_mr_substring);
    while (ext) {
        for (i = 0; ext->values && ext->values[i]; i++) {
            printf("\t %s      : %s\n", ext->term, ext->values[i]);
        }
        ext = ext->next;
    }
    printf("\tplugin: %p\n", a->asi_plugin);
    printf("--------------\n");

    return HT_ENUMERATE_NEXT;
}

void
attr_syntax_print(void)
{
    printf("*** attr_syntax_print ***\n");
    PL_HashTableEnumerateEntries(name2asi, attr_syntax_printnode, 0);
}

#endif


/* lowercase the attr name and chop trailing spaces */
/* note that s may contain options also, e.g., userCertificate;binary */
char *
attr_syntax_normalize_no_lookup_ext(char *s, int flags)
{
    char *save, *tmps;

    tmps = slapi_ch_strdup(s);
    for (save = tmps; (*tmps != '\0') && (*tmps != ' '); tmps++) {
        *tmps = TOLOWER(*tmps);
    }
    *tmps = '\0';
    if (flags & ATTR_SYNTAX_NORM_ORIG_ATTR) {
        /* Chop trailing spaces + following strings */
        *(s + (tmps - save)) = '\0';
    }

    return save;
}

char *
attr_syntax_normalize_no_lookup(const char *s)
{
    char *save, *tmps;

    tmps = slapi_ch_strdup(s);
    for (save = tmps; (*tmps != '\0') && (*tmps != ' '); tmps++) {
        *tmps = TOLOWER(*tmps);
    }
    *tmps = '\0';

    return save;
}

struct enum_arg_wrapper
{
    AttrEnumFunc aef;
    void *arg;
};

PRIntn
attr_syntax_enumerate_internal(PLHashEntry *he, PRIntn i, void *arg)
{
    struct enum_arg_wrapper *eaw = (struct enum_arg_wrapper *)arg;
    int rc;

    rc = (eaw->aef)((struct asyntaxinfo *)he->value, eaw->arg);
    if (ATTR_SYNTAX_ENUM_STOP == rc) {
        rc = HT_ENUMERATE_STOP;
    } else if (ATTR_SYNTAX_ENUM_REMOVE == rc) {
        rc = HT_ENUMERATE_REMOVE;
    } else {
        rc = HT_ENUMERATE_NEXT;
    }

    return rc;
}

static void
attr_syntax_enumerate_attrs_ext(PLHashTable *ht,
                                AttrEnumFunc aef,
                                void *arg)
{
    struct enum_arg_wrapper eaw;
    eaw.aef = aef;
    eaw.arg = arg;

    if (!ht)
        return;

    PL_HashTableEnumerateEntries(ht, attr_syntax_enumerate_internal, &eaw);
}

void
attr_syntax_enumerate_attrs(AttrEnumFunc aef, void *arg, PRBool writelock)
{
    if (!oid2asi)
        return;

    if (writelock) {
        AS_LOCK_WRITE(oid2asi_lock);
        AS_LOCK_WRITE(name2asi_lock);
    } else {
        AS_LOCK_READ(oid2asi_lock);
        AS_LOCK_READ(name2asi_lock);
    }

    attr_syntax_enumerate_attrs_ext(oid2asi, aef, arg);

    if (writelock) {
        AS_UNLOCK_WRITE(name2asi_lock);
        AS_UNLOCK_WRITE(oid2asi_lock);
    } else {
        AS_UNLOCK_READ(name2asi_lock);
        AS_UNLOCK_READ(oid2asi_lock);
    }
}


struct attr_syntax_enum_flaginfo
{
    unsigned long asef_flag;
};

static int
attr_syntax_clear_flag_callback(struct asyntaxinfo *asip, void *arg)
{
    struct attr_syntax_enum_flaginfo *fi;

    PR_ASSERT(asip != NULL);
    fi = (struct attr_syntax_enum_flaginfo *)arg;
    PR_ASSERT(fi != NULL);

    asip->asi_flags &= ~(fi->asef_flag);

    return ATTR_SYNTAX_ENUM_NEXT;
}


static int
attr_syntax_delete_if_not_flagged(struct asyntaxinfo *asip, void *arg)
{
    struct attr_syntax_enum_flaginfo *fi;

    PR_ASSERT(asip != NULL);
    fi = (struct attr_syntax_enum_flaginfo *)arg;
    PR_ASSERT(fi != NULL);

    if (0 == (asip->asi_flags & fi->asef_flag)) {
        attr_syntax_delete_no_lock(asip, PR_FALSE, 0);
        return ATTR_SYNTAX_ENUM_REMOVE;
    } else {
        return ATTR_SYNTAX_ENUM_NEXT;
    }
}

static int
attr_syntax_force_to_delete(struct asyntaxinfo *asip, void *arg)
{
    PR_ASSERT(asip != NULL);

    attr_syntax_delete_no_lock(asip, PR_FALSE, 0);
    return ATTR_SYNTAX_ENUM_REMOVE;
}


/*
 * Clear 'flag' within all attribute definitions.
 */
void
attr_syntax_all_clear_flag(unsigned long flag)
{
    struct attr_syntax_enum_flaginfo fi = {0};

    fi.asef_flag = flag;
    attr_syntax_enumerate_attrs(attr_syntax_clear_flag_callback,
                                (void *)&fi, PR_TRUE);
}


/*
 * Delete all attribute definitions that do not contain any bits of 'flag'
 * in their flags.
 */
void
attr_syntax_delete_all_not_flagged(unsigned long flag)
{
    struct attr_syntax_enum_flaginfo fi = {0};

    fi.asef_flag = flag;
    attr_syntax_enumerate_attrs(attr_syntax_delete_if_not_flagged,
                                (void *)&fi, PR_TRUE);
}

/*
 * Delete all attribute definitions
 */
void
attr_syntax_delete_all()
{
    struct attr_syntax_enum_flaginfo fi = {0};

    attr_syntax_enumerate_attrs(attr_syntax_force_to_delete,
                                (void *)&fi, PR_TRUE);
}

/*
 * Delete all attribute definitions without attr_syntax lock.
 * The caller is responsible for the lock.
 */
void
attr_syntax_delete_all_for_schemareload(unsigned long flag)
{
    struct attr_syntax_enum_flaginfo fi = {0};

    fi.asef_flag = flag;
    attr_syntax_enumerate_attrs_ext(oid2asi, attr_syntax_delete_if_not_flagged,
                                    (void *)&fi);
}

#define ATTR_DEFAULT_SYNTAX_OID "1.1"
#define ATTR_DEFAULT_SYNTAX "defaultdirstringsyntax"

static int
attr_syntax_init(void)
{
    int schema_modify_enabled = config_get_schemamod();
    if (!schema_modify_enabled)
        asi_locking = 0;

    if (!oid2asi) {
        oid2asi = PL_NewHashTable(2047, hashNocaseString,
                                  hashNocaseCompare,
                                  PL_CompareValues, 0, 0);
        if (asi_locking && NULL == (oid2asi_lock = slapi_new_rwlock())) {
            if (oid2asi)
                PL_HashTableDestroy(oid2asi);
            oid2asi = NULL;

            slapi_log_err(SLAPI_LOG_ERR, "attr_syntax_init",
                          "slapi_new_rwlock() for oid2asi lock failed\n");
            return 1;
        }
    }

    if (!oid2asi_tmp) {
        /* temporary hash table for schema reload */
        oid2asi_tmp = PL_NewHashTable(2047, hashNocaseString,
                                      hashNocaseCompare,
                                      PL_CompareValues, 0, 0);
    }

    if (!name2asi) {
        name2asi = PL_NewHashTable(2047, hashNocaseString,
                                   hashNocaseCompare,
                                   PL_CompareValues, 0, 0);
        if (asi_locking && NULL == (name2asi_lock = slapi_new_rwlock())) {
            if (name2asi)
                PL_HashTableDestroy(name2asi);
            name2asi = NULL;

            slapi_log_err(SLAPI_LOG_ERR, "attr_syntax_init",
                          "slapi_new_rwlock() for oid2asi lock failed\n");
            return 1;
        }
        /* add a default syntax plugin as fallback, required during startup
        */
        attr_syntax_create_default(ATTR_DEFAULT_SYNTAX,
                                   ATTR_DEFAULT_SYNTAX_OID,
                                   DIRSTRING_SYNTAX_OID,
                                   SLAPI_ATTR_FLAG_NOUSERMOD | SLAPI_ATTR_FLAG_NOEXPOSE);
    }
    if (!name2asi_tmp) {
        /* temporary hash table for schema reload */
        name2asi_tmp = PL_NewHashTable(2047, hashNocaseString,
                                       hashNocaseCompare,
                                       PL_CompareValues, 0, 0);
    }

    return 0;
}

int
slapi_attr_syntax_exists(const char *attr_name)
{
    return attr_syntax_exists(attr_name);
}

/*
 * Keep the internally added schema in the hash table,
 * which are re-added if the schema is reloaded.
 */
static int
attr_syntax_internal_asi_add_ht(struct asyntaxinfo *asip)
{
    if (!internalasi) {
        internalasi = PL_NewHashTable(64, hashNocaseString,
                                      hashNocaseCompare,
                                      PL_CompareValues, 0, 0);
    }
    if (!internalasi) {
        slapi_log_err(SLAPI_LOG_ERR, "attr_syntax_internal_asi_add_ht",
                      "Failed to create HashTable.\n");
        return 1;
    }
    if (!PL_HashTableLookup(internalasi, asip->asi_oid)) {
        struct asyntaxinfo *asip_copy = attr_syntax_dup(asip);
        if (!asip_copy) {
            slapi_log_err(SLAPI_LOG_ERR, "attr_syntax_internal_asi_add_ht",
                          "Failed to duplicate asyntaxinfo: %s.\n",
                          asip->asi_name);
            return 1;
        }
        PL_HashTableAdd(internalasi, asip_copy->asi_oid, asip_copy);
    }
    return 0;
}

/*
 * Add an attribute syntax using some default flags, etc.
 * Returns an LDAP error code (LDAP_SUCCESS if all goes well)
 */
int
slapi_add_internal_attr_syntax(const char *name, const char *oid, const char *syntax, const char *mr_equality, unsigned long extraflags)
{
    int rc = LDAP_SUCCESS;
    struct asyntaxinfo *asip;
    char *names[2];
    unsigned long std_flags = SLAPI_ATTR_FLAG_STD_ATTR | SLAPI_ATTR_FLAG_OPATTR;

    names[0] = (char *)name;
    names[1] = NULL;

    rc = attr_syntax_create(oid, names,
                            "internal server defined attribute type",
                            NULL,                    /* superior */
                            mr_equality, NULL, NULL, /* matching rules */
                            NULL, syntax,
                            SLAPI_SYNTAXLENGTH_NONE,
                            std_flags | extraflags,
                            &asip);

    if (rc == LDAP_SUCCESS) {
        rc = attr_syntax_add(asip, 0);
        if (rc == LDAP_SUCCESS) {
            if (attr_syntax_internal_asi_add_ht(asip)) {
                slapi_log_err(SLAPI_LOG_ERR,
                              "slapi_add_internal_attr_syntax",
                              "Failed to stash internal asyntaxinfo: %s.\n",
                              asip->asi_name);
            }
        } else {
            attr_syntax_free(asip);
        }
    }

    return rc;
}

/* Adding internal asyncinfo via slapi_reload_internal_attr_syntax */
static int
attr_syntax_internal_asi_add(struct asyntaxinfo *asip, void *arg)
{
    struct asyntaxinfo *asip_copy;
    int rc = 0;

    if (!asip) {
        return 1;
    }
    /* Copy is needed since when reloading the schema,
     * existing syntax info is cleaned up. */
    asip_copy = attr_syntax_dup(asip);
    rc = attr_syntax_add(asip_copy, 0);
    if (LDAP_SUCCESS != rc) {
        attr_syntax_free(asip_copy);
    }
    return rc;
}

/* Reload internal attribute syntax stashed in the internalasi hashtable. */
int
slapi_reload_internal_attr_syntax()
{
    int rc = LDAP_SUCCESS;
    if (!internalasi) {
        slapi_log_err(SLAPI_LOG_TRACE, "attr_reload_internal_attr_syntax",
                      "No internal attribute syntax to reload.\n");
        return rc;
    }
    attr_syntax_enumerate_attrs_ext(internalasi, attr_syntax_internal_asi_add, NULL);
    return rc;
}

/*
 * See if the attribute at1 is in the list of at2.  Change by name, and oid(if necessary).
 */
struct asyntaxinfo *
attr_syntax_find(struct asyntaxinfo *at1, struct asyntaxinfo *at2)
{
    struct asyntaxinfo *asi;

    for (asi = at2; asi != NULL; asi = asi->asi_next) {
        if (strcasecmp(at1->asi_name, asi->asi_name) == 0 || strcmp(at1->asi_oid, asi->asi_oid) == 0) {
            /* found it */
            return asi;
        }
    }

    return NULL;
}

/*
 * schema reload - now that we have loaded the schema into temporary
 * hash tables and linked lists, swap out the old for the new.  Then
 * reload the internal attr syntaxes
 */
void
attr_syntax_swap_ht()
{
    struct asyntaxinfo *next;

    /* Remove the old hash tables */
    PL_HashTableDestroy(name2asi);
    PL_HashTableDestroy(oid2asi);

    /* Free the global attr linked list */
    while (global_at) {
        next = global_at->asi_next;
        attr_syntax_free(global_at);
        global_at = next;
    }

    /*
     * Swap the hash table/linked list pointers, and set the
     * temporary pointers to NULL
     */
    name2asi = name2asi_tmp;
    name2asi_tmp = NULL;
    oid2asi = oid2asi_tmp;
    oid2asi_tmp = NULL;
    global_at = global_at_tmp;
    global_at_tmp = NULL;
}