winbind/idmap_ad: be verbose about the user that we fail to map

[Samba.git] / lib / ldb / common / ldb_msg.c

/* 
   ldb database library

   Copyright (C) Andrew Tridgell  2004

     ** NOTE! The following LGPL license applies to the ldb
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

/*
 *  Name: ldb
 *
 *  Component: ldb message component utility functions
 *
 *  Description: functions for manipulating ldb_message structures
 *
 *  Author: Andrew Tridgell
 */

#include "ldb_private.h"

/*
  create a new ldb_message in a given memory context (NULL for top level)
*/
struct ldb_message *ldb_msg_new(TALLOC_CTX *mem_ctx)
{
        return talloc_zero(mem_ctx, struct ldb_message);
}

/*
  find an element in a message by attribute name
*/
struct ldb_message_element *ldb_msg_find_element(const struct ldb_message *msg, 
                                                 const char *attr_name)
{
        unsigned int i;
        for (i=0;i<msg->num_elements;i++) {
                if (ldb_attr_cmp(msg->elements[i].name, attr_name) == 0) {
                        return &msg->elements[i];
                }
        }
        return NULL;
}

/*
  see if two ldb_val structures contain exactly the same data
  return 1 for a match, 0 for a mis-match
*/
int ldb_val_equal_exact(const struct ldb_val *v1, const struct ldb_val *v2)
{
        if (v1->length != v2->length) return 0;
        if (v1->data == v2->data) return 1;
        if (v1->length == 0) return 1;

        if (memcmp(v1->data, v2->data, v1->length) == 0) {
                return 1;
        }

        return 0;
}

/*
  find a value in an element
  assumes case sensitive comparison
*/
struct ldb_val *ldb_msg_find_val(const struct ldb_message_element *el, 
                                 struct ldb_val *val)
{
        unsigned int i;
        for (i=0;i<el->num_values;i++) {
                if (ldb_val_equal_exact(val, &el->values[i])) {
                        return &el->values[i];
                }
        }
        return NULL;
}

/*
  duplicate a ldb_val structure
*/
struct ldb_val ldb_val_dup(TALLOC_CTX *mem_ctx, const struct ldb_val *v)
{
        struct ldb_val v2;
        v2.length = v->length;
        if (v->data == NULL) {
                v2.data = NULL;
                return v2;
        }

        /* the +1 is to cope with buggy C library routines like strndup
           that look one byte beyond */
        v2.data = talloc_array(mem_ctx, uint8_t, v->length+1);
        if (!v2.data) {
                v2.length = 0;
                return v2;
        }

        memcpy(v2.data, v->data, v->length);
        ((char *)v2.data)[v->length] = 0;
        return v2;
}

/**
 * Adds new empty element to msg->elements
 */
static int _ldb_msg_add_el(struct ldb_message *msg,
                           struct ldb_message_element **return_el)
{
        struct ldb_message_element *els;

        /*
         * TODO: Find out a way to assert on input parameters.
         * msg and return_el must be valid
         */

        els = talloc_realloc(msg, msg->elements,
                             struct ldb_message_element, msg->num_elements + 1);
        if (!els) {
                return LDB_ERR_OPERATIONS_ERROR;
        }

        ZERO_STRUCT(els[msg->num_elements]);

        msg->elements = els;
        msg->num_elements++;

        *return_el = &els[msg->num_elements-1];

        return LDB_SUCCESS;
}

/**
 * Add an empty element with a given name to a message
 */
int ldb_msg_add_empty(struct ldb_message *msg,
                      const char *attr_name,
                      int flags,
                      struct ldb_message_element **return_el)
{
        int ret;
        struct ldb_message_element *el;

        ret = _ldb_msg_add_el(msg, &el);
        if (ret != LDB_SUCCESS) {
                return ret;
        }

        /* initialize newly added element */
        el->flags = flags;
        el->name = talloc_strdup(msg->elements, attr_name);
        if (!el->name) {
                return LDB_ERR_OPERATIONS_ERROR;
        }

        if (return_el) {
                *return_el = el;
        }

        return LDB_SUCCESS;
}

/**
 * Adds an element to a message.
 *
 * NOTE: Ownership of ldb_message_element fields
 *       is NOT transferred. Thus, if *el pointer
 *       is invalidated for some reason, this will
 *       corrupt *msg contents also
 */
int ldb_msg_add(struct ldb_message *msg, 
                const struct ldb_message_element *el, 
                int flags)
{
        int ret;
        struct ldb_message_element *el_new;
        /* We have to copy this, just in case *el is a pointer into
         * what ldb_msg_add_empty() is about to realloc() */
        struct ldb_message_element el_copy = *el;

        ret = _ldb_msg_add_el(msg, &el_new);
        if (ret != LDB_SUCCESS) {
                return ret;
        }

        el_new->flags      = flags;
        el_new->name       = el_copy.name;
        el_new->num_values = el_copy.num_values;
        el_new->values     = el_copy.values;

        return LDB_SUCCESS;
}

/*
  add a value to a message
*/
int ldb_msg_add_value(struct ldb_message *msg, 
                      const char *attr_name,
                      const struct ldb_val *val,
                      struct ldb_message_element **return_el)
{
        struct ldb_message_element *el;
        struct ldb_val *vals;
        int ret;

        el = ldb_msg_find_element(msg, attr_name);
        if (!el) {
                ret = ldb_msg_add_empty(msg, attr_name, 0, &el);
                if (ret != LDB_SUCCESS) {
                        return ret;
                }
        }

        vals = talloc_realloc(msg->elements, el->values, struct ldb_val,
                              el->num_values+1);
        if (!vals) {
                return LDB_ERR_OPERATIONS_ERROR;
        }
        el->values = vals;
        el->values[el->num_values] = *val;
        el->num_values++;

        if (return_el) {
                *return_el = el;
        }

        return LDB_SUCCESS;
}


/*
  add a value to a message, stealing it into the 'right' place
*/
int ldb_msg_add_steal_value(struct ldb_message *msg, 
                            const char *attr_name,
                            struct ldb_val *val)
{
        int ret;
        struct ldb_message_element *el;

        ret = ldb_msg_add_value(msg, attr_name, val, &el);
        if (ret == LDB_SUCCESS) {
                talloc_steal(el->values, val->data);
        }
        return ret;
}


/*
  add a string element to a message
*/
int ldb_msg_add_string(struct ldb_message *msg, 
                       const char *attr_name, const char *str)
{
        struct ldb_val val;

        val.data = discard_const_p(uint8_t, str);
        val.length = strlen(str);

        if (val.length == 0) {
                /* allow empty strings as non-existent attributes */
                return LDB_SUCCESS;
        }

        return ldb_msg_add_value(msg, attr_name, &val, NULL);
}

/*
  add a string element to a message, stealing it into the 'right' place
*/
int ldb_msg_add_steal_string(struct ldb_message *msg, 
                             const char *attr_name, char *str)
{
        struct ldb_val val;

        val.data = (uint8_t *)str;
        val.length = strlen(str);

        if (val.length == 0) {
                /* allow empty strings as non-existent attributes */
                return LDB_SUCCESS;
        }

        return ldb_msg_add_steal_value(msg, attr_name, &val);
}

/*
  add a DN element to a message
  WARNING: this uses the linearized string from the dn, and does not
  copy the string.
*/
int ldb_msg_add_linearized_dn(struct ldb_message *msg, const char *attr_name,
                              struct ldb_dn *dn)
{
        char *str = ldb_dn_alloc_linearized(msg, dn);

        if (str == NULL) {
                /* we don't want to have unknown DNs added */
                return LDB_ERR_OPERATIONS_ERROR;
        }

        return ldb_msg_add_steal_string(msg, attr_name, str);
}

/*
  add a printf formatted element to a message
*/
int ldb_msg_add_fmt(struct ldb_message *msg, 
                    const char *attr_name, const char *fmt, ...)
{
        struct ldb_val val;
        va_list ap;
        char *str;

        va_start(ap, fmt);
        str = talloc_vasprintf(msg, fmt, ap);
        va_end(ap);

        if (str == NULL) return LDB_ERR_OPERATIONS_ERROR;

        val.data   = (uint8_t *)str;
        val.length = strlen(str);

        return ldb_msg_add_steal_value(msg, attr_name, &val);
}

/*
  compare two ldb_message_element structures
  assumes case sensitive comparison
*/
int ldb_msg_element_compare(struct ldb_message_element *el1, 
                            struct ldb_message_element *el2)
{
        unsigned int i;

        if (el1->num_values != el2->num_values) {
                return el1->num_values - el2->num_values;
        }

        for (i=0;i<el1->num_values;i++) {
                if (!ldb_msg_find_val(el2, &el1->values[i])) {
                        return -1;
                }
        }

        return 0;
}

/*
  compare two ldb_message_element structures.
  Different ordering is considered a mismatch
*/
bool ldb_msg_element_equal_ordered(const struct ldb_message_element *el1,
                                   const struct ldb_message_element *el2)
{
        unsigned i;
        if (el1->num_values != el2->num_values) {
                return false;
        }
        for (i=0;i<el1->num_values;i++) {
                if (ldb_val_equal_exact(&el1->values[i],
                                        &el2->values[i]) != 1) {
                        return false;
                }
        }
        return true;
}

/*
  compare two ldb_message_element structures
  comparing by element name
*/
int ldb_msg_element_compare_name(struct ldb_message_element *el1, 
                                 struct ldb_message_element *el2)
{
        return ldb_attr_cmp(el1->name, el2->name);
}

/*
  convenience functions to return common types from a message
  these return the first value if the attribute is multi-valued
*/
const struct ldb_val *ldb_msg_find_ldb_val(const struct ldb_message *msg, 
                                           const char *attr_name)
{
        struct ldb_message_element *el = ldb_msg_find_element(msg, attr_name);
        if (!el || el->num_values == 0) {
                return NULL;
        }
        return &el->values[0];
}

int ldb_msg_find_attr_as_int(const struct ldb_message *msg, 
                             const char *attr_name,
                             int default_value)
{
        const struct ldb_val *v = ldb_msg_find_ldb_val(msg, attr_name);
        char buf[sizeof("-2147483648")];
        char *end = NULL;
        int ret;

        if (!v || !v->data) {
                return default_value;
        }

        ZERO_STRUCT(buf);
        if (v->length >= sizeof(buf)) {
                return default_value;
        }

        memcpy(buf, v->data, v->length);
        errno = 0;
        ret = (int) strtoll(buf, &end, 10);
        if (errno != 0) {
                return default_value;
        }
        if (end && end[0] != '\0') {
                return default_value;
        }
        return ret;
}

unsigned int ldb_msg_find_attr_as_uint(const struct ldb_message *msg,
                                       const char *attr_name,
                                       unsigned int default_value)
{
        const struct ldb_val *v = ldb_msg_find_ldb_val(msg, attr_name);
        char buf[sizeof("-2147483648")];
        char *end = NULL;
        unsigned int ret;

        if (!v || !v->data) {
                return default_value;
        }

        ZERO_STRUCT(buf);
        if (v->length >= sizeof(buf)) {
                return default_value;
        }

        memcpy(buf, v->data, v->length);
        errno = 0;
        ret = (unsigned int) strtoll(buf, &end, 10);
        if (errno != 0) {
                errno = 0;
                ret = (unsigned int) strtoull(buf, &end, 10);
                if (errno != 0) {
                        return default_value;
                }
        }
        if (end && end[0] != '\0') {
                return default_value;
        }
        return ret;
}

int64_t ldb_msg_find_attr_as_int64(const struct ldb_message *msg, 
                                   const char *attr_name,
                                   int64_t default_value)
{
        const struct ldb_val *v = ldb_msg_find_ldb_val(msg, attr_name);
        char buf[sizeof("-9223372036854775808")];
        char *end = NULL;
        int64_t ret;

        if (!v || !v->data) {
                return default_value;
        }

        ZERO_STRUCT(buf);
        if (v->length >= sizeof(buf)) {
                return default_value;
        }

        memcpy(buf, v->data, v->length);
        errno = 0;
        ret = (int64_t) strtoll(buf, &end, 10);
        if (errno != 0) {
                return default_value;
        }
        if (end && end[0] != '\0') {
                return default_value;
        }
        return ret;
}

uint64_t ldb_msg_find_attr_as_uint64(const struct ldb_message *msg,
                                     const char *attr_name,
                                     uint64_t default_value)
{
        const struct ldb_val *v = ldb_msg_find_ldb_val(msg, attr_name);
        char buf[sizeof("-9223372036854775808")];
        char *end = NULL;
        uint64_t ret;

        if (!v || !v->data) {
                return default_value;
        }

        ZERO_STRUCT(buf);
        if (v->length >= sizeof(buf)) {
                return default_value;
        }

        memcpy(buf, v->data, v->length);
        errno = 0;
        ret = (uint64_t) strtoll(buf, &end, 10);
        if (errno != 0) {
                errno = 0;
                ret = (uint64_t) strtoull(buf, &end, 10);
                if (errno != 0) {
                        return default_value;
                }
        }
        if (end && end[0] != '\0') {
                return default_value;
        }
        return ret;
}

double ldb_msg_find_attr_as_double(const struct ldb_message *msg, 
                                   const char *attr_name,
                                   double default_value)
{
        const struct ldb_val *v = ldb_msg_find_ldb_val(msg, attr_name);
        char *buf;
        char *end = NULL;
        double ret;

        if (!v || !v->data) {
                return default_value;
        }
        buf = talloc_strndup(msg, (const char *)v->data, v->length);
        if (buf == NULL) {
                return default_value;
        }

        errno = 0;
        ret = strtod(buf, &end);
        talloc_free(buf);
        if (errno != 0) {
                return default_value;
        }
        if (end && end[0] != '\0') {
                return default_value;
        }
        return ret;
}

int ldb_msg_find_attr_as_bool(const struct ldb_message *msg, 
                              const char *attr_name,
                              int default_value)
{
        const struct ldb_val *v = ldb_msg_find_ldb_val(msg, attr_name);
        if (!v || !v->data) {
                return default_value;
        }
        if (v->length == 5 && strncasecmp((const char *)v->data, "FALSE", 5) == 0) {
                return 0;
        }
        if (v->length == 4 && strncasecmp((const char *)v->data, "TRUE", 4) == 0) {
                return 1;
        }
        return default_value;
}

const char *ldb_msg_find_attr_as_string(const struct ldb_message *msg, 
                                        const char *attr_name,
                                        const char *default_value)
{
        const struct ldb_val *v = ldb_msg_find_ldb_val(msg, attr_name);
        if (!v || !v->data) {
                return default_value;
        }
        if (v->data[v->length] != '\0') {
                return default_value;
        }
        return (const char *)v->data;
}

struct ldb_dn *ldb_msg_find_attr_as_dn(struct ldb_context *ldb,
                                       TALLOC_CTX *mem_ctx,
                                       const struct ldb_message *msg,
                                       const char *attr_name)
{
        struct ldb_dn *res_dn;
        const struct ldb_val *v;

        v = ldb_msg_find_ldb_val(msg, attr_name);
        if (!v || !v->data) {
                return NULL;
        }
        res_dn = ldb_dn_from_ldb_val(mem_ctx, ldb, v);
        if ( ! ldb_dn_validate(res_dn)) {
                talloc_free(res_dn);
                return NULL;
        }
        return res_dn;
}

/*
  sort the elements of a message by name
*/
void ldb_msg_sort_elements(struct ldb_message *msg)
{
        TYPESAFE_QSORT(msg->elements, msg->num_elements,
                       ldb_msg_element_compare_name);
}

/*
  shallow copy a message - copying only the elements array so that the caller
  can safely add new elements without changing the message
*/
struct ldb_message *ldb_msg_copy_shallow(TALLOC_CTX *mem_ctx, 
                                         const struct ldb_message *msg)
{
        struct ldb_message *msg2;
        unsigned int i;

        msg2 = talloc(mem_ctx, struct ldb_message);
        if (msg2 == NULL) return NULL;

        *msg2 = *msg;

        msg2->elements = talloc_array(msg2, struct ldb_message_element, 
                                      msg2->num_elements);
        if (msg2->elements == NULL) goto failed;

        for (i=0;i<msg2->num_elements;i++) {
                msg2->elements[i] = msg->elements[i];
        }

        return msg2;

failed:
        talloc_free(msg2);
        return NULL;
}


/*
  copy a message, allocating new memory for all parts
*/
struct ldb_message *ldb_msg_copy(TALLOC_CTX *mem_ctx, 
                                 const struct ldb_message *msg)
{
        struct ldb_message *msg2;
        unsigned int i, j;

        msg2 = ldb_msg_copy_shallow(mem_ctx, msg);
        if (msg2 == NULL) return NULL;

        msg2->dn = ldb_dn_copy(msg2, msg2->dn);
        if (msg2->dn == NULL) goto failed;

        for (i=0;i<msg2->num_elements;i++) {
                struct ldb_message_element *el = &msg2->elements[i];
                struct ldb_val *values = el->values;
                el->name = talloc_strdup(msg2->elements, el->name);
                if (el->name == NULL) goto failed;
                el->values = talloc_array(msg2->elements, struct ldb_val, el->num_values);
                if (el->values == NULL) goto failed;
                for (j=0;j<el->num_values;j++) {
                        el->values[j] = ldb_val_dup(el->values, &values[j]);
                        if (el->values[j].data == NULL && values[j].length != 0) {
                                goto failed;
                        }
                }
        }

        return msg2;

failed:
        talloc_free(msg2);
        return NULL;
}


/**
 * Canonicalize a message, merging elements of the same name
 */
struct ldb_message *ldb_msg_canonicalize(struct ldb_context *ldb, 
                                         const struct ldb_message *msg)
{
        int ret;
        struct ldb_message *msg2;

        /*
         * Preserve previous behavior and allocate
         * *msg2 into *ldb context
         */
        ret = ldb_msg_normalize(ldb, ldb, msg, &msg2);
        if (ret != LDB_SUCCESS) {
                return NULL;
        }

        return msg2;
}

/**
 * Canonicalize a message, merging elements of the same name
 */
int ldb_msg_normalize(struct ldb_context *ldb,
                      TALLOC_CTX *mem_ctx,
                      const struct ldb_message *msg,
                      struct ldb_message **_msg_out)
{
        unsigned int i;
        struct ldb_message *msg2;

        msg2 = ldb_msg_copy(mem_ctx, msg);
        if (msg2 == NULL) {
                return LDB_ERR_OPERATIONS_ERROR;
        }

        ldb_msg_sort_elements(msg2);

        for (i=1; i < msg2->num_elements; i++) {
                struct ldb_message_element *el1 = &msg2->elements[i-1];
                struct ldb_message_element *el2 = &msg2->elements[i];

                if (ldb_msg_element_compare_name(el1, el2) == 0) {
                        el1->values = talloc_realloc(msg2->elements,
                                                     el1->values, struct ldb_val,
                                                     el1->num_values + el2->num_values);
                        if (el1->num_values + el2->num_values > 0 && el1->values == NULL) {
                                talloc_free(msg2);
                                return LDB_ERR_OPERATIONS_ERROR;
                        }
                        memcpy(el1->values + el1->num_values,
                               el2->values,
                               sizeof(struct ldb_val) * el2->num_values);
                        el1->num_values += el2->num_values;
                        talloc_free(discard_const_p(char, el2->name));
                        if ((i+1) < msg2->num_elements) {
                                memmove(el2, el2+1, sizeof(struct ldb_message_element) *
                                        (msg2->num_elements - (i+1)));
                        }
                        msg2->num_elements--;
                        i--;
                }
        }

        *_msg_out = msg2;
        return LDB_SUCCESS;
}


/**
 * return a ldb_message representing the differences between msg1 and msg2.
 * If you then use this in a ldb_modify() call,
 * it can be used to save edits to a message
 */
struct ldb_message *ldb_msg_diff(struct ldb_context *ldb, 
                                 struct ldb_message *msg1,
                                 struct ldb_message *msg2)
{
        int ldb_ret;
        struct ldb_message *mod;

        ldb_ret = ldb_msg_difference(ldb, ldb, msg1, msg2, &mod);
        if (ldb_ret != LDB_SUCCESS) {
                return NULL;
        }

        return mod;
}

/**
 * return a ldb_message representing the differences between msg1 and msg2.
 * If you then use this in a ldb_modify() call it can be used to save edits to a message
 *
 * Result message is constructed as follows:
 * - LDB_FLAG_MOD_ADD     - elements found only in msg2
 * - LDB_FLAG_MOD_REPLACE - elements in msg2 that have different value in msg1
 *                          Value for msg2 element is used
 * - LDB_FLAG_MOD_DELETE  - elements found only in msg2
 *
 * @return LDB_SUCCESS or LDB_ERR_OPERATIONS_ERROR
 */
int ldb_msg_difference(struct ldb_context *ldb,
                       TALLOC_CTX *mem_ctx,
                       struct ldb_message *msg1,
                       struct ldb_message *msg2,
                       struct ldb_message **_msg_out)
{
        int ldb_res;
        unsigned int i;
        struct ldb_message *mod;
        struct ldb_message_element *el;
        TALLOC_CTX *temp_ctx;

        temp_ctx = talloc_new(mem_ctx);
        if (!temp_ctx) {
                return LDB_ERR_OPERATIONS_ERROR;
        }

        mod = ldb_msg_new(temp_ctx);
        if (mod == NULL) {
                goto failed;
        }

        mod->dn = msg1->dn;
        mod->num_elements = 0;
        mod->elements = NULL;

        /*
         * Canonicalize *msg2 so we have no repeated elements
         * Resulting message is allocated in *mod's mem context,
         * as we are going to move some elements from *msg2 to
         * *mod object later
         */
        ldb_res = ldb_msg_normalize(ldb, mod, msg2, &msg2);
        if (ldb_res != LDB_SUCCESS) {
                goto failed;
        }

        /* look in msg2 to find elements that need to be added or modified */
        for (i=0;i<msg2->num_elements;i++) {
                el = ldb_msg_find_element(msg1, msg2->elements[i].name);

                if (el && ldb_msg_element_compare(el, &msg2->elements[i]) == 0) {
                        continue;
                }

                ldb_res = ldb_msg_add(mod,
                                      &msg2->elements[i],
                                      el ? LDB_FLAG_MOD_REPLACE : LDB_FLAG_MOD_ADD);
                if (ldb_res != LDB_SUCCESS) {
                        goto failed;
                }
        }

        /* look in msg1 to find elements that need to be deleted */
        for (i=0;i<msg1->num_elements;i++) {
                el = ldb_msg_find_element(msg2, msg1->elements[i].name);
                if (el == NULL) {
                        ldb_res = ldb_msg_add_empty(mod,
                                                    msg1->elements[i].name,
                                                    LDB_FLAG_MOD_DELETE, NULL);
                        if (ldb_res != LDB_SUCCESS) {
                                goto failed;
                        }
                }
        }

        /* steal resulting message into supplied context */
        talloc_steal(mem_ctx, mod);
        *_msg_out = mod;

        talloc_free(temp_ctx);
        return LDB_SUCCESS;

failed:
        talloc_free(temp_ctx);
        return LDB_ERR_OPERATIONS_ERROR;
}


int ldb_msg_sanity_check(struct ldb_context *ldb, 
                         const struct ldb_message *msg)
{
        unsigned int i, j;

        /* basic check on DN */
        if (msg->dn == NULL) {
                ldb_set_errstring(ldb, "ldb message lacks a DN!");
                return LDB_ERR_INVALID_DN_SYNTAX;
        }

        /* basic syntax checks */
        for (i = 0; i < msg->num_elements; i++) {
                for (j = 0; j < msg->elements[i].num_values; j++) {
                        if (msg->elements[i].values[j].length == 0) {
                                /* an attribute cannot be empty */
                                ldb_asprintf_errstring(ldb, "Element %s has empty attribute in ldb message (%s)!",
                                                            msg->elements[i].name, 
                                                            ldb_dn_get_linearized(msg->dn));
                                return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
                        }
                }
        }

        return LDB_SUCCESS;
}




/*
  copy an attribute list. This only copies the array, not the elements
  (ie. the elements are left as the same pointers)
*/
const char **ldb_attr_list_copy(TALLOC_CTX *mem_ctx, const char * const *attrs)
{
        const char **ret;
        unsigned int i;

        for (i=0;attrs && attrs[i];i++) /* noop */ ;
        ret = talloc_array(mem_ctx, const char *, i+1);
        if (ret == NULL) {
                return NULL;
        }
        for (i=0;attrs && attrs[i];i++) {
                ret[i] = attrs[i];
        }
        ret[i] = attrs[i];
        return ret;
}


/*
  copy an attribute list. This only copies the array, not the elements
  (ie. the elements are left as the same pointers).  The new attribute is added to the list.
*/
const char **ldb_attr_list_copy_add(TALLOC_CTX *mem_ctx, const char * const *attrs, const char *new_attr)
{
        const char **ret;
        unsigned int i;
        bool found = false;

        for (i=0;attrs && attrs[i];i++) {
                if (ldb_attr_cmp(attrs[i], new_attr) == 0) {
                        found = true;
                }
        }
        if (found) {
                return ldb_attr_list_copy(mem_ctx, attrs);
        }
        ret = talloc_array(mem_ctx, const char *, i+2);
        if (ret == NULL) {
                return NULL;
        }
        for (i=0;attrs && attrs[i];i++) {
                ret[i] = attrs[i];
        }
        ret[i] = new_attr;
        ret[i+1] = NULL;
        return ret;
}


/*
  return 1 if an attribute is in a list of attributes, or 0 otherwise
*/
int ldb_attr_in_list(const char * const *attrs, const char *attr)
{
        unsigned int i;
        for (i=0;attrs && attrs[i];i++) {
                if (ldb_attr_cmp(attrs[i], attr) == 0) {
                        return 1;
                }
        }
        return 0;
}


/*
  rename the specified attribute in a search result
*/
int ldb_msg_rename_attr(struct ldb_message *msg, const char *attr, const char *replace)
{
        struct ldb_message_element *el = ldb_msg_find_element(msg, attr);
        if (el == NULL) {
                return LDB_SUCCESS;
        }
        el->name = talloc_strdup(msg->elements, replace);
        if (el->name == NULL) {
                return LDB_ERR_OPERATIONS_ERROR;
        }
        return LDB_SUCCESS;
}


/*
  copy the specified attribute in a search result to a new attribute
*/
int ldb_msg_copy_attr(struct ldb_message *msg, const char *attr, const char *replace)
{
        struct ldb_message_element *el = ldb_msg_find_element(msg, attr);
        int ret;

        if (el == NULL) {
                return LDB_SUCCESS;
        }
        ret = ldb_msg_add(msg, el, 0);
        if (ret != LDB_SUCCESS) {
                return ret;
        }
        return ldb_msg_rename_attr(msg, attr, replace);
}

/*
  remove the specified element in a search result
*/
void ldb_msg_remove_element(struct ldb_message *msg, struct ldb_message_element *el)
{
        ptrdiff_t n = (el - msg->elements);
        if (n >= msg->num_elements) {
                /* should we abort() here? */
                return;
        }
        if (n != msg->num_elements-1) {
                memmove(el, el+1, ((msg->num_elements-1) - n)*sizeof(*el));
        }
        msg->num_elements--;
}


/*
  remove the specified attribute in a search result
*/
void ldb_msg_remove_attr(struct ldb_message *msg, const char *attr)
{
        struct ldb_message_element *el;

        while ((el = ldb_msg_find_element(msg, attr)) != NULL) {
                ldb_msg_remove_element(msg, el);
        }
}

/*
  return a LDAP formatted GeneralizedTime string
*/
char *ldb_timestring(TALLOC_CTX *mem_ctx, time_t t)
{
        struct tm *tm = gmtime(&t);
        char *ts;
        int r;

        if (!tm) {
                return NULL;
        }

        /* we now excatly how long this string will be */
        ts = talloc_array(mem_ctx, char, 18);

        /* formatted like: 20040408072012.0Z */
        r = snprintf(ts, 18,
                        "%04u%02u%02u%02u%02u%02u.0Z",
                        tm->tm_year+1900, tm->tm_mon+1,
                        tm->tm_mday, tm->tm_hour, tm->tm_min,
                        tm->tm_sec);

        if (r != 17) {
                talloc_free(ts);
                return NULL;
        }

        return ts;
}

/*
  convert a LDAP GeneralizedTime string to a time_t. Return 0 if unable to convert
*/
time_t ldb_string_to_time(const char *s)
{
        struct tm tm;
        
        if (s == NULL) return 0;
        
        memset(&tm, 0, sizeof(tm));
        if (sscanf(s, "%04u%02u%02u%02u%02u%02u.0Z",
                   &tm.tm_year, &tm.tm_mon, &tm.tm_mday, 
                   &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
                return 0;
        }
        tm.tm_year -= 1900;
        tm.tm_mon -= 1;
        
        return timegm(&tm);
}

/*
  convert a LDAP GeneralizedTime string in ldb_val format to a
  time_t.
*/
int ldb_val_to_time(const struct ldb_val *v, time_t *t)
{
        struct tm tm;

        if (v == NULL || !v->data || (v->length != 17 && v->length != 13)) {
                return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
        }

        memset(&tm, 0, sizeof(tm));

        if (v->length == 13) {
                if (sscanf((char *)v->data, "%02u%02u%02u%02u%02u%02uZ",
                        &tm.tm_year, &tm.tm_mon, &tm.tm_mday,
                        &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
                        return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
                }
        } else {
                if (sscanf((char *)v->data, "%04u%02u%02u%02u%02u%02u.0Z",
                        &tm.tm_year, &tm.tm_mon, &tm.tm_mday,
                        &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
                        return LDB_ERR_INVALID_ATTRIBUTE_SYNTAX;
                }
        }
        tm.tm_year -= 1900;
        tm.tm_mon -= 1;

        *t = timegm(&tm);

        return LDB_SUCCESS;
}

/*
  return a LDAP formatted UTCTime string
*/
char *ldb_timestring_utc(TALLOC_CTX *mem_ctx, time_t t)
{
        struct tm *tm = gmtime(&t);
        char *ts;
        int r;

        if (!tm) {
                return NULL;
        }

        /* we now excatly how long this string will be */
        ts = talloc_array(mem_ctx, char, 14);

        /* formatted like: 20040408072012.0Z => 040408072012Z */
        r = snprintf(ts, 14,
                        "%02u%02u%02u%02u%02u%02uZ",
                        (tm->tm_year+1900)%100, tm->tm_mon+1,
                        tm->tm_mday, tm->tm_hour, tm->tm_min,
                        tm->tm_sec);

        if (r != 13) {
                talloc_free(ts);
                return NULL;
        }

        return ts;
}

/*
  convert a LDAP UTCTime string to a time_t. Return 0 if unable to convert
*/
time_t ldb_string_utc_to_time(const char *s)
{
        struct tm tm;
        
        if (s == NULL) return 0;
        
        memset(&tm, 0, sizeof(tm));
        if (sscanf(s, "%02u%02u%02u%02u%02u%02uZ",
                   &tm.tm_year, &tm.tm_mon, &tm.tm_mday, 
                   &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
                return 0;
        }
        if (tm.tm_year < 50) {
                tm.tm_year += 100;
        }
        tm.tm_mon -= 1;
        
        return timegm(&tm);
}


/*
  dump a set of results to a file. Useful from within gdb
*/
void ldb_dump_results(struct ldb_context *ldb, struct ldb_result *result, FILE *f)
{
        unsigned int i;

        for (i = 0; i < result->count; i++) {
                struct ldb_ldif ldif;
                fprintf(f, "# record %d\n", i+1);
                ldif.changetype = LDB_CHANGETYPE_NONE;
                ldif.msg = result->msgs[i];
                ldb_ldif_write_file(ldb, f, &ldif);
        }
}

/*
  checks for a string attribute. Returns "1" on match and otherwise "0".
*/
int ldb_msg_check_string_attribute(const struct ldb_message *msg,
                                   const char *name, const char *value)
{
        struct ldb_message_element *el;
        struct ldb_val val;
        
        el = ldb_msg_find_element(msg, name);
        if (el == NULL) {
                return 0;
        }

        val.data = discard_const_p(uint8_t, value);
        val.length = strlen(value);

        if (ldb_msg_find_val(el, &val)) {
                return 1;
        }

        return 0;
}


/*
  compare a ldb_val to a string
*/
int ldb_val_string_cmp(const struct ldb_val *v, const char *str)
{
        size_t len = strlen(str);
        if (len != v->length) {
                return len - v->length;
        }
        return strncmp((const char *)v->data, str, len);
}