edit.c

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/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: caf694c869fb8d3668136682770825f01427b4ab $
 *
 * @brief fr_pair_t editing
 *
 * @ingroup AVP
 *
 * @copyright 2021 Network RADIUS SAS (legal@networkradius.com)
 */
RCSID("$Id: caf694c869fb8d3668136682770825f01427b4ab $")
 
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/server/tmpl_dcursor.h>
#include <freeradius-devel/util/edit.h>
#include <freeradius-devel/util/calc.h>
#include <freeradius-devel/unlang/tmpl.h>
#include <freeradius-devel/unlang/edit.h>
#include <freeradius-devel/unlang/transaction.h>
#include <freeradius-devel/unlang/unlang_priv.h>
#include "edit_priv.h"
 
#undef XDEBUG
#if 1
#define XDEBUG(...)
#else
#define XDEBUG DEBUG2
#endif
 
#define RDEBUG_ASSIGN(_name, _op, _box) do { \
        RDEBUG2(((_box)->type == FR_TYPE_STRING) ? "%s %s \"%pV\"" : "%s %s %pV", _name, fr_tokens[_op], _box); \
} while (0)
 
typedef struct {
        fr_value_box_list_t     result;                 //!< result of expansion
        tmpl_t const            *vpt;                   //!< expanded tmpl
        tmpl_t                  *to_free;               //!< tmpl to free.
        bool                    create;                 //!< whether we need to create the VP
        fr_pair_t               *vp;                    //!< VP referenced by tmpl.
        fr_pair_t               *vp_parent;             //!< parent of the current VP
        fr_pair_list_t          pair_list;              //!< for structural attributes
} edit_result_t;
 
typedef struct edit_map_s edit_map_t;
 
typedef struct unlang_frame_state_edit_s unlang_frame_state_edit_t;
 
typedef int (*unlang_edit_expand_t)(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current);
 
struct edit_map_s {
        fr_edit_list_t          *el;                    //!< edit list
 
        TALLOC_CTX              *ctx;
        edit_map_t              *parent;
        edit_map_t              *child;
 
        map_list_t const        *map_list;
        map_t const             *map;                   //!< the map to evaluate
 
        bool                    temporary_pair_list;
 
        edit_result_t           lhs;                    //!< LHS child entries
        edit_result_t           rhs;                    //!< RHS child entries
 
        unlang_edit_expand_t    func;                   //!< for process state
        unlang_edit_expand_t    check_lhs;              //!< for special cases
        unlang_edit_expand_t    expanded_lhs;           //!< for special cases
};
 
/** State of an edit block
 *
 */
struct unlang_frame_state_edit_s {
        fr_edit_list_t          *el;                    //!< edit list
        bool                    *success;               //!< whether or not the edit succeeded
        bool                    ours;
 
        rindent_t               indent;
 
        edit_map_t              *current;               //!< what we're currently doing.
        edit_map_t              first;
};
 
#define MAP_INFO cf_filename(map->ci), cf_lineno(map->ci)
 
static fr_pair_t *edit_list_pair_build(fr_pair_t *parent, fr_dcursor_t *cursor, fr_dict_attr_t const *da, void *uctx);
 
/*
 *  Convert a value-box list to a LHS attribute #tmpl_t
 */
static int tmpl_attr_from_result(TALLOC_CTX *ctx, map_t const *map, edit_result_t *out, request_t *request)
{
        ssize_t slen;
        fr_value_box_t *box = fr_value_box_list_head(&out->result);
 
        if (!box) {
                RWDEBUG("%s %s ... - Assignment failed - No value on right-hand side", map->lhs->name, fr_tokens[map->op]);
                return -1;
        }
 
        /*
         *      Mash all of the results together.
         */
        if (fr_value_box_list_concat_in_place(box, box, &out->result, FR_TYPE_STRING, FR_VALUE_BOX_LIST_FREE, true, SIZE_MAX) < 0) {
                RWDEBUG("Failed converting result to string");
                return -1;
        }
 
        /*
         *      Parse the LHS as an attribute reference.  It can't be
         *      anything else.
         */
        slen = tmpl_afrom_attr_str(ctx, NULL, &out->to_free, box->vb_strvalue,
                                   &(tmpl_rules_t){
                                        .attr = {
                                                .dict_def = request->local_dict,
                                                .list_def = request_attr_request,
                                        }
                                   });
        if (slen <= 0) {
                RPEDEBUG("Expansion result \"%s\" is not an attribute reference", box->vb_strvalue);
                return -1;
        }
 
        out->vpt = out->to_free;
        fr_value_box_list_talloc_free(&out->result);
 
        return 0;
}
 
 
/*
 *      Expand a tmpl.
 */
static int tmpl_to_values(TALLOC_CTX *ctx, edit_result_t *out, request_t *request, tmpl_t const *vpt)
{
        fr_assert(out->vpt == NULL);
        fr_assert(out->to_free == NULL);
 
        switch (vpt->type) {
        case TMPL_TYPE_DATA:
                return 0;
 
        case TMPL_TYPE_ATTR:
                out->vpt = vpt;
                return 0;
 
        case TMPL_TYPE_EXEC:
                if (unlang_tmpl_push(ctx, &out->result, request, vpt, NULL) < 0) return -1;
                return 1;
 
        case TMPL_TYPE_XLAT:
                if (unlang_xlat_push(ctx, NULL, &out->result, request, tmpl_xlat(vpt), false) < 0) return -1;
                return 1;
 
        default:
                /*
                 *      The other tmpl types MUST have already been
                 *      converted to the "realized" types.
                 */
                tmpl_debug(vpt);
                fr_assert(0);
                break;
        }
 
        return -1;
}
 
static void edit_debug_attr_list(request_t *request, fr_pair_list_t const *list, map_t const *map);
 
static void edit_debug_attr_vp(request_t *request, fr_pair_t *vp, map_t const *map)
{
        fr_assert(vp != NULL);
 
        if (map) {
                switch (vp->vp_type) {
                case FR_TYPE_STRUCTURAL:
                        RDEBUG2("%s = {", map->lhs->name);
                        RINDENT();
                        edit_debug_attr_list(request, &vp->vp_group, map_list_head(&map->child));
                        REXDENT();
                        RDEBUG2("}");
                        break;
 
                default:
                        RDEBUG_ASSIGN(map->lhs->name, vp->op, &vp->data);
                        break;
                }
        } else {
                switch (vp->vp_type) {
                case FR_TYPE_STRUCTURAL:
                        RDEBUG2("%s = {", vp->da->name);
                        RINDENT();
                        edit_debug_attr_list(request, &vp->vp_group, NULL);
                        REXDENT();
                        RDEBUG2("}");
                        break;
 
                default:
                        RDEBUG_ASSIGN(vp->da->name, vp->op, &vp->data);
                        break;
                }
        }
}
 
static void edit_debug_attr_list(request_t *request, fr_pair_list_t const *list, map_t const *map)
{
        fr_pair_t *vp;
        map_t const *child = NULL;
 
        if (map) child = map_list_head(&map->child);
 
        for (vp = fr_pair_list_next(list, NULL);
             vp != NULL;
             vp = fr_pair_list_next(list, vp)) {
                edit_debug_attr_vp(request, vp, child);
                if (map) child = map_list_next(&map->child, child);
        }
}
 
static int edit_create_lhs_vp(request_t *request, TALLOC_CTX *ctx, edit_map_t *current)
{
        int err;
        fr_pair_t *vp;
        tmpl_dcursor_ctx_t lhs_cc;
        fr_dcursor_t lhs_cursor;
 
        fr_assert(current->lhs.create);
 
        /*
         *      Now that we have the RHS values, go create the LHS vp.  We delay creating it until
         *      now, because the RHS might just be nothing.  In which case we don't want to create the
         *      LHS, and then discover that we need to delete it.
         */
        fr_strerror_clear();
        vp = tmpl_dcursor_build_init(&err, ctx, &lhs_cc, &lhs_cursor, request, current->lhs.vpt, edit_list_pair_build, current);
        tmpl_dcursor_clear(&lhs_cc);
        if (!vp) {
                RPEDEBUG("Failed creating attribute %s", current->lhs.vpt->name);
                return -1;
        }
 
        current->lhs.vp = vp;
 
        return 0;
}
 
/*      Apply the edits to a structural attribute..
 *
 *      Figure out what edits to do, and then do them.
 */
static int apply_edits_to_list(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        fr_pair_t *vp;
        fr_pair_list_t *children;
        int rcode;
        map_t const *map = current->map;
        tmpl_dcursor_ctx_t cc;
        fr_dcursor_t cursor;
 
        XDEBUG("apply_edits_to_list %s", map->lhs->name);
 
        /*
         *      RHS is a sublist, go apply that.
         */
        if (!map->rhs) {
                children = &current->rhs.pair_list;
                goto apply_list;
        }
 
        /*
         *      For RHS of data, it should be a string which contains the pairs to use.
         */
        if (!current->rhs.vpt) {
                fr_value_box_t *box;
                fr_dict_attr_t const *da;
                fr_pair_parse_t root, relative;
 
                if (tmpl_is_data(map->rhs)) {
                        box = tmpl_value(map->rhs);
 
                        if (box->type != FR_TYPE_STRING) {
                                REDEBUG("Invalid data type for assignment to list");
                                return -1;
                        }
 
                } else {
                        box = fr_value_box_list_head(&current->rhs.result);
 
                        /*
                         *      Can't concatenate empty results.
                         */
                        if (!box) {
                                RWDEBUG("%s %s ... - Assignment failed to having no value on right-hand side", map->lhs->name, fr_tokens[map->op]);
                                return -1;
                        }
 
                        /*
                         *      Mash all of the results together.
                         */
                        if (fr_value_box_list_concat_in_place(box, box, &current->rhs.result, FR_TYPE_STRING, FR_VALUE_BOX_LIST_FREE, true, SIZE_MAX) < 0) {
                                RWDEBUG("Failed converting result to string");
                                return -1;
                        }
                }
 
                children = &current->rhs.pair_list;
 
                /*
                 *      For exec, etc., parse the pair list from a string, in the context of the
                 *      parent VP.  Because we're going to be moving them to the parent VP at some
                 *      point.  The ones which aren't moved will get deleted in this function.
                 */
                da = tmpl_attr_tail_da(current->lhs.vpt);
                if (fr_type_is_group(da->type)) da = fr_dict_root(request->proto_dict);
 
                root = (fr_pair_parse_t) {
                        .ctx = current->ctx,
                        .da = da,
                        .list = children,
                        .allow_compare = true,
                        .tainted = box->tainted,
                };
                relative = (fr_pair_parse_t) { };
 
                if (fr_pair_list_afrom_substr(&root, &relative, &FR_SBUFF_IN(box->vb_strvalue, box->vb_length)) < 0) {
                        RPEDEBUG("Failed parsing string '%pV' as attribute list", box);
                        return -1;
                }
 
                goto apply_list;
        }
 
        fr_assert(current->rhs.vpt);
        fr_assert(tmpl_is_attr(current->rhs.vpt));
 
        /*
         *      Doing no modifications to a list is a NOOP.
         */
        vp = tmpl_dcursor_init(NULL, request, &cc, &cursor, request, current->rhs.vpt);
        if (!vp) {
                tmpl_dcursor_clear(&cc);
                return 0;
        }
 
        /*
         *      Remove an attribute from a list.  The tmpl_dcursor and tmpl_parser ensures that the RHS
         *      references are done in the context of the LHS attribute.
         */
        if (map->op == T_OP_SUB_EQ) {
                fr_pair_t *next;
 
                /*
                 *      Loop over matching attributes, and delete them.
                 */
                RDEBUG2("%s %s %s", current->lhs.vpt->name, fr_tokens[T_OP_SUB_EQ], current->rhs.vpt->name);
 
                for ( ; vp != NULL; vp = next) {
                        fr_pair_list_t *list;
 
                        next = fr_dcursor_next(&cursor);
 
                        list = fr_pair_parent_list(vp);
                        fr_assert(list != NULL);
 
                        /*
                         *      @todo - if this attribute is structural, then remove all children which aren't
                         *      immutable.  For now, this is good enough.
                         */
                        if (fr_pair_immutable(vp)) {
                                RWDEBUG("Not removing immutable %pP", vp);
                                continue;
                        }
 
                        if (vp->vp_edit) {
                                RWDEBUG("Attribute cannot be removed, as it is being used in a 'foreach' loop - %pP", vp);
                                continue;
                        }
 
                        if (fr_edit_list_pair_delete(current->el, list, vp) < 0) {
                                RPEDEBUG("Failed deleting attribute");
                                tmpl_dcursor_clear(&cc);
                                return -1;
                        }
                }
 
                tmpl_dcursor_clear(&cc);
                return 0;
        }
 
        /*
         *      Check the RHS thing we're copying.
         */
        if (fr_type_is_structural(vp->vp_type)) {
                tmpl_dcursor_clear(&cc);
 
                if (tmpl_attr_tail_num(current->rhs.vpt) == NUM_ALL) {
                        REDEBUG("%s[%d] Wildcard for structural attribute %s is not yet implemented.", MAP_INFO, current->rhs.vpt->name);
                        return -1;
                }
 
                children = &vp->vp_group;
                goto apply_list;
        }
 
        /*
         *      Copy the attributes from the cursor to a temporary pair list.
         */
        fr_pair_list_init(&current->rhs.pair_list);
        while (vp) {
                fr_pair_t *copy;
 
                copy = fr_pair_copy(request, vp);
                if (!copy) {
                        fr_pair_list_free(&current->rhs.pair_list);
                        tmpl_dcursor_clear(&cc);
                        return -1;
                }
                fr_pair_append(&current->rhs.pair_list, copy);
 
                vp = fr_dcursor_next(&cursor);
        }
        tmpl_dcursor_clear(&cc);
 
        children = &current->rhs.pair_list;
 
        /*
         *      Apply structural thingies!
         */
apply_list:
        fr_assert(children != NULL);
 
        /*
         *      If we have to create the LHS, then do so now.
         */
        if (current->lhs.create && (edit_create_lhs_vp(request, state, current) < 0)) {
                return -1;
        }
 
        fr_assert(current->lhs.vp != NULL);
 
#ifdef STATIC_ANALYZER
        if (!current->lhs.vp) return -1;
#endif
 
        /*
         *      Print the children before we do the modifications.
         */
        if (!current->parent) {
                RDEBUG2("%s %s {", current->lhs.vpt->name, fr_tokens[map->op]);
                if (fr_debug_lvl >= L_DBG_LVL_2) {
                        RINDENT();
                        edit_debug_attr_list(request, children, map);
                        REXDENT();
                }
                RDEBUG2("}");
        }
 
        fr_pair_list_foreach(children, child) {
                if (!fr_dict_attr_can_contain(current->lhs.vp->da, child->da)) {
                        RDEBUG("Cannot perform assignment: Attribute \"%s\" is not a child of parent \"%s\"",
                               child->da->name, current->lhs.vp->da->name);
                        rcode = -1;
                        goto done;
                }
        }
 
        if (map->op != T_OP_EQ) {
                fr_assert(current->el != NULL);
 
                rcode = fr_edit_list_apply_list_assignment(current->el, current->lhs.vp, map->op, children,
                                                           (children != &current->rhs.pair_list));
                if (rcode < 0) RPEDEBUG("Failed performing list '%s' operation", fr_tokens[map->op]);
 
        } else {
#if 0
                /*
                 *      The RHS list _should_ be a copy of the LHS list.  But for some cases it's not.  We
                 *      should spend time tracking this down, but not today.
                 *
                 *      For now, brute-force copy isn't wrong.
                 */
                if (children == &current->rhs.pair_list) {
                        fr_pair_list_append(&current->lhs.vp->vp_group, children);
                } else
#endif
                (void) fr_pair_list_copy(current->lhs.vp, &current->lhs.vp->vp_group, children);
 
                PAIR_VERIFY(current->lhs.vp);
                rcode = 0;
        }
 
        /*
         *      If the child list wasn't copied, then we just created it, and we need to free it.
         */
done:
        if (children == &current->rhs.pair_list) fr_pair_list_free(children);
        return rcode;
}
 
static bool pair_is_editable(request_t *request, fr_pair_t *vp)
{
        if (vp->vp_edit) {
                RWDEBUG("Attribute cannot be removed, as it is being used in a 'foreach' loop - %s", vp->da->name);
                return false;
        }
 
        if (!fr_type_is_structural(vp->vp_type)) return true;
 
        fr_pair_list_foreach(&vp->vp_group, child) {
                if (!pair_is_editable(request, child)) return false;
        }
 
        return true;
}
 
static int edit_delete_lhs(request_t *request, edit_map_t *current, bool delete)
{
        tmpl_dcursor_ctx_t cc;
        fr_dcursor_t cursor;
 
        /*
         *      These are magic.
         */
        if (delete) {
                fr_dict_attr_t const *da = tmpl_attr_tail_da(current->lhs.vpt);
 
                if (fr_type_is_structural(da->type) &&
                    ((da == request_attr_request) ||
                     (da == request_attr_reply) ||
                     (da == request_attr_control) ||
                     (da == request_attr_state))) {
                        delete = false;
                }
        }
 
        while (true) {
                int err;
                fr_pair_t *vp, *parent;
 
                /*
                 *      Reinitialize the cursor for every VP.  This is because fr_dcursor_remove() does not
                 *      work with tmpl_dcursors, as the tmpl_dcursor code does not set the "remove" callback.
                 *      And the tmpl is NUM_UNSPEC, which means "the first one", whereas for T_OP_SET_EQ, we
                 *      really mean "delete all except the first one".
                 *
                 *      Once that's implemented, we also need to update the edit list API to
                 *      allow for "please delete children"?
                 */
                vp = tmpl_dcursor_init(&err, current->ctx, &cc, &cursor, request, current->lhs.vpt);
                if (!vp) break;
 
                parent = fr_pair_parent(vp);
                fr_assert(parent != NULL);
 
                if (!pair_is_editable(request, vp)) {
                        tmpl_dcursor_clear(&cc);
                        return -1;
                }
 
                if (!delete) {
                        if (fr_type_is_structural(vp->vp_type)) {
 
                                if (fr_edit_list_free_pair_children(current->el, vp) < 0) return -1;
                        } else {
                                /*
                                 *      No need to save value, as fr_edit_list_apply_pair_assignment() will do
                                 *      that for us.
                                 */
                        }
 
                        current->lhs.vp = vp;
                        tmpl_dcursor_clear(&cc);
                        return 0;
                }
 
                /*
                 *      Delete all of them.  We'll create one later for the SET operation.
                 */
                if (fr_edit_list_pair_delete(current->el, &parent->vp_group, vp) < 0) {
                        RPWDEBUG("Failed deleting attribute");
                        return -1;
                }
                tmpl_dcursor_clear(&cc);
        }
 
        return 0;
}
 
/*
 *      Apply the edits to a leaf attribute.  First we figure out where the results come from:
 *
 *              single value-box (e.g. tmpl_is_data(vpt)
 *              rhs value-box result list (we create a dcursor)
 *              RHS attribute reference (we create a nested dcursor to get the values from the pair list)
 *
 *      Then we figure out what to do with those values.
 *
 *              if it needs to be created, then create it and just mash the results in place
 *              otherwise apply the edits (+=, etc.) to an existing attribute.
 *
 *      @todo - move to using dcursors for all of the values.  The dcursor should exist in current->rhs.  It
 *      should be used even for TMPL_DATA and single value-boxes.  Once that's done, it becomes easier to use
 *      dcursors for xlats, too.
 */
static int apply_edits_to_leaf(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        fr_value_box_t *box = NULL;
        tmpl_dcursor_ctx_t cc;
        fr_dcursor_t cursor;
        fr_dcursor_t pair_cursor;
        bool single = false, pair = false;
        map_t const *map = current->map;
 
        XDEBUG("apply_edits_to_leaf %s", map->lhs->name);
 
        if (!tmpl_is_attr(current->lhs.vpt)) {
                REDEBUG("%s[%d] The left side of an assignment must be an attribute reference", MAP_INFO);
                return -1;
        }
 
        /*
         *      &Foo := { a, b, c }
         *
         *      There should be values in RHS result, all of value boxes.
         */
        if (!map->rhs) {
                fr_assert(current->rhs.vpt == NULL);
                goto rhs_list;
 
        }
 
        if (!current->rhs.vpt) {
                /*
                 *      There's no RHS tmpl, so the result must be in in the parent RHS tmpl as data, OR in
                 *      the RHS result list.
                 */
                if (tmpl_is_data(map->rhs)) {
                        box = tmpl_value(map->rhs);
                        single = true;
 
                } else if ((map->rhs->quote == T_SINGLE_QUOTED_STRING) || (map->rhs->quote == T_DOUBLE_QUOTED_STRING)) {
                        /*
                         *      The caller asked for a string, so instead of returning a list, return a string.
                         *
                         *      If there's no output, then it's an empty string.
                         *
                         *      We have to check this here, because the quote is part of the tmpl, and we call
                         *      xlat_push(), which doesn't know about the quote.
                         *
                         *      @todo - we should really push the quote into the xlat, too.
                         */
                        box = fr_value_box_list_head(&current->rhs.result);
 
                        if (!box) {
                                MEM(box = fr_value_box_alloc(state, FR_TYPE_STRING, NULL));
                                fr_value_box_strdup(box, box, NULL, "", false);
                                fr_value_box_list_insert_tail(&current->rhs.result, box);
 
                        } else if (fr_value_box_list_concat_in_place(box, box, &current->rhs.result, FR_TYPE_STRING,
                                                              FR_VALUE_BOX_LIST_FREE_BOX, true, 8192) < 0) {
                                RWDEBUG("Failed converting result to string");
                                return -1;
                        }
                        box = fr_value_box_list_head(&current->rhs.result);
                        single = true;
 
                } else {
                rhs_list:
                        if (fr_value_box_list_num_elements(&current->rhs.result) == 1) {
                                box = fr_value_box_list_head(&current->rhs.result);
                                single = true;
                        } else {
                                box = fr_dcursor_init(&cursor, fr_value_box_list_dlist_head(&current->rhs.result));
                        }
                }
        } else {
                fr_pair_t *vp;
                int err;
 
                /*
                 *      We have a temporary tmpl on the RHS.  It MUST be an attribute, because everything else
                 *      was expanded to a value-box list.
                 */
                fr_assert(tmpl_is_attr(current->rhs.vpt));
 
                /*
                 *      Get a cursor over the RHS pairs.
                 */
                vp = tmpl_dcursor_init(&err, request, &cc, &pair_cursor, request, current->rhs.vpt);
                if (!vp) {
                        tmpl_dcursor_clear(&cc);
 
                        if (map->op != T_OP_SET) return 0;
 
                        /*
                         *      No RHS pairs means we can finally delete all of the LHS.
                         */
                        return edit_delete_lhs(request, current, true);
                }
 
                box = fr_pair_dcursor_nested_init(&cursor, &pair_cursor); // the list is unused
                pair = true;
        }
 
        if (!box) {
                if (map->op != T_OP_SET) {
                        RWDEBUG("%s %s ... - Assignment failed - No value on right-hand side", map->lhs->name, fr_tokens[map->op]);
                        return -1;
                }
 
                /*
                 *      Set is "delete, then add".
                 */
                RDEBUG2("%s :=", current->lhs.vpt->name);
                goto done;
        }
 
        /*
         *      The parent is a structural type.  The RHS is a temporary list or attribute, which we can just
         *      add to the parents pair list.  The parent will then take care of merging that pair list into
         *      the appropriate place.
         */
        if (current->temporary_pair_list) {
                fr_pair_list_t *list = &current->parent->rhs.pair_list;
                fr_pair_t *vp;
 
                if (!current->parent->lhs.vp) {
                        if (edit_create_lhs_vp(request, request, current->parent) < 0) return -1;
                }
 
                while (box) {
                        /*
                         *      Create (or find) all intermediate attributes.  The LHS map might have multiple
                         *      attribute names in it.
                         *
                         *      @todo - audit other uses of tmpl_attr_tail_da() and fr_pair_afrom_da() in this file.
                         */
                        if (pair_append_by_tmpl_parent(current->parent->lhs.vp, &vp, list, current->lhs.vpt, true) < 0) {
                                RPEDEBUG("Failed creating attribute %s", current->lhs.vpt->name);
                                return -1;
                        }
 
                        vp->op = map->op;
                        if (fr_value_box_cast(vp, &vp->data, vp->vp_type, vp->da, box) < 0) return -1;
 
                        if (single) break;
 
                        box = fr_dcursor_next(&cursor);
                }
 
                goto done;
        }
 
        /*
         *      If we're supposed to create the LHS, then go do that.
         */
        if (current->lhs.create) {
                fr_dict_attr_t const *da = tmpl_attr_tail_da(current->lhs.vpt);
                fr_pair_t *vp;
 
                /*
                 *      Something went wrong creating the value, it's a failure.  Note that we fail _all_
                 *      subsequent assignments, too.
                 */
                if (fr_type_is_null(box->type)) goto fail;
 
                if (edit_create_lhs_vp(request, state, current) < 0) goto fail;
 
                fr_assert(current->lhs.vp_parent != NULL);
                fr_assert(fr_type_is_structural(current->lhs.vp_parent->vp_type));
 
                vp = current->lhs.vp;
 
                /*
                 *      There's always at least one LHS vp created.  So we apply that first.
                 */
                RDEBUG_ASSIGN(current->lhs.vpt->name, map->op, box);
 
                /*
                 *      The VP has already been inserted into the edit list, so we don't need to edit it's
                 *      value, we can just mash it in place.
                 */
                if (fr_value_box_cast(vp, &vp->data, vp->vp_type, vp->da, box) < 0) goto fail;
                vp->op = T_OP_EQ;
                if (vp->da->flags.unsafe) fr_value_box_mark_unsafe(&vp->data);
 
                if (single) goto done;
 
                /*
                 *      Now that the attribute has been created, go apply the rest of the values to the attribute.
                 */
                if (!((map->op == T_OP_EQ) || (map->op == T_OP_SET))) {
                        box = fr_dcursor_next(&cursor);
                        if (!box) goto done;
 
                        goto apply_op;
                }
 
                if (current->lhs.vp->da->flags.local) {
                        if (fr_dcursor_next_peek(&cursor)) RWDEBUG("Ignoring extra values for local variable");
                        goto done;
                }
 
                /*
                 *      Loop over the remaining items, adding the VPs we've just created.
                 */
                while ((box = fr_dcursor_next(&cursor)) != NULL) {
                        RDEBUG_ASSIGN(current->lhs.vpt->name, map->op, box);
 
                        MEM(vp = fr_pair_afrom_da(current->lhs.vp_parent, da));
                        if (fr_value_box_cast(vp, &vp->data, vp->vp_type, vp->da, box) < 0) goto fail;
                        if (vp->da->flags.unsafe) fr_value_box_mark_unsafe(&vp->data);
 
                        if (fr_edit_list_insert_pair_tail(state->el, &current->lhs.vp_parent->vp_group, vp) < 0) goto fail;
                        vp->op = T_OP_EQ;
                }
 
                goto done;
        }
 
        /*
         *      If we're not creating a temporary list, we must be editing an existing attribute on the LHS.
         *
         *      We have two remaining cases.  One is the attribute was just created with "=" or ":=", so we
         *      can just mash its value.  The second is that the attribute already exists, and we're editing
         *      it's value using something like "+=".
         */
        fr_assert(current->lhs.vp != NULL);
 
#ifdef STATIC_ANALYZER
        if (!current->lhs.vp) return -1;
#endif
 
apply_op:
        /*
         *      All other operators are "modify in place", of the existing current->lhs.vp
         */
        while (box) {
                RDEBUG_ASSIGN(current->lhs.vpt->name, map->op, box);
                if (current->lhs.vp->da->flags.unsafe) fr_value_box_mark_unsafe(box);
 
                /*
                 *      The apply function also takes care of doing data type upcasting and conversion.  So we don't
                 *      have to check for compatibility of the data types on the LHS and RHS.
                 */
                if (fr_edit_list_apply_pair_assignment(current->el,
                                                       current->lhs.vp,
                                                       map->op,
                                                       box) < 0) {
                fail:
                        RPEDEBUG("Assigning value to %s failed", map->lhs->name);
                        if (pair) tmpl_dcursor_clear(&cc);
                        return -1;
                }
 
                if (single) break;
 
                box = fr_dcursor_next(&cursor);
        }
 
done:
        if (pair) tmpl_dcursor_clear(&cc);
        fr_value_box_list_talloc_free(&current->rhs.result);
 
        return 0;
}
 
 
/** Simple pair building callback for use with tmpl_dcursors
 *
 *  Which always appends the new pair to the tail of the list
 *  since it is only called when no matching pairs were found when
 *  walking the list.
 *
 *  Note that this function is called for all intermediate nodes which are built!
 *
 *
 *
 * @param[in] parent            to allocate new pair within.
 * @param[in,out] cursor        to append new pair to.
 * @param[in] da                of new pair.
 * @param[in] uctx              unused.
 * @return
 *      - newly allocated #fr_pair_t.
 *      - NULL on error.
 */
static fr_pair_t *edit_list_pair_build(fr_pair_t *parent, fr_dcursor_t *cursor, fr_dict_attr_t const *da, void *uctx)
{
        fr_pair_t *vp;
        edit_map_t *current = uctx;
 
        vp = fr_pair_afrom_da(parent, da);
        if (!vp) return NULL;
 
        current->lhs.vp_parent = parent;
        current->lhs.vp = vp;
 
        if (fr_edit_list_insert_pair_tail(current->el, &parent->vp_group, vp) < 0) {
                talloc_free(vp);
                return NULL;
        }
 
        /*
         *      Tell the cursor that we appended a pair.  This
         *      function only gets called when we've ran off of the
         *      end of the list, and can't find the thing we're
         *      looking for.  So it's safe at set the current one
         *      here.
         *
         *      @todo - mainly only because we don't allow creating
         *      foo[4] when there's <3 matching entries.  i.e. the
         *      "arrays" here are really lists, so we can't create
         *      "holes" in the list.
         */
        fr_dcursor_set_current(cursor, vp);
 
        return vp;
}
 
#define DECLARE(_x) static int _x(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
 
DECLARE(expand_lhs);
DECLARE(check_lhs);
DECLARE(check_lhs_value);
DECLARE(check_lhs_nested);
DECLARE(expanded_lhs_attribute);
DECLARE(expanded_lhs_value);
 
/*
 *      Clean up the current state, and go to the next map.
 */
static int next_map(UNUSED request_t *request, UNUSED unlang_frame_state_edit_t *state, edit_map_t *current)
{
        TALLOC_FREE(current->lhs.to_free);
        TALLOC_FREE(current->rhs.to_free);
        fr_pair_list_free(&current->rhs.pair_list);
        current->lhs.vp = NULL;
        current->lhs.vp_parent = NULL;
        current->lhs.vpt = NULL;
        current->rhs.vpt = NULL;
 
        current->map = map_list_next(current->map_list, current->map);
        current->func = expand_lhs;
 
        /*
         *      Don't touch the other callbacks.
         */
 
        return 0;
}
 
/*
 *      Validate the RHS of an expansion.
 */
static int check_rhs(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        map_t const *map = current->map;
 
        XDEBUG("%s map %s %s ...", __FUNCTION__, map->lhs->name, fr_tokens[map->op]);
 
        /*
         *      := is "remove all matching, and then add".  So if even if we don't add anything, we still remove things.
         *
         *      If we deleted the attribute when processing the LHS, then you couldn't reference an attribute
         *      in it's own assignment:
         *
         *              &foo := %tolower(foo)
         *
         *      so we have to delay the deletion until the RHS has been fully expanded.  But we don't always
         *      delete everything. e.g. if the map is:
         *
         *              &foo[1] := %tolower(foo[1])
         *
         *      The we just apply the assignment to the LHS, over-writing it's value.
         */
        if ((map->op == T_OP_SET) &&
            ((tmpl_attr_tail_num(current->lhs.vpt) == NUM_UNSPEC) || (tmpl_attr_tail_num(current->lhs.vpt) > 0) ||
             !current->map->rhs)) {
                if (edit_delete_lhs(request, current,
                                    (tmpl_attr_tail_num(current->lhs.vpt) == NUM_UNSPEC) || !current->map->rhs) < 0) return -1;
        }
 
        /*
         *      @todo - Realize the RHS box value.  By moving the code in apply_edits_to_leaf() to a common function,
         *      and getting the box dcursor here.
         *
         *      Then, get a cursor for the LHS vp, and loop over it, applying the edits in the operator, using
         *      the comparisons in the RHS box.
         *
         *      This lets us use array indexes (or more complex things) on the LHS, and means that we don't
         *      have to realize the VPs and use horrible hacks.
         */
        if (current->parent && (current->parent->map->op == T_OP_SUB_EQ)) {
                fr_assert(current->temporary_pair_list);
                fr_assert(tmpl_is_attr(current->lhs.vpt)); /* can only apply edits to real attributes */
                fr_assert(map->rhs);                       /* can only filter on leaf attributes */
 
#if 0
                {
                        // dcursor_init over current->lhs.vpt, using children of current->parent.lhs_vp
                        //
                        // and then use the dcursor from the apply_edits_to_leaf() to get value-boxes
                        rcode = fr_value_box_cmp_op(map->op, &vp->data, box);
                        if (rcode < 0) return -1;
 
                        if (!rcode) continue;
 
                        if (fr_edit_list_pair_delete(el, list, vp) < 0) return -1;
                }
 
                return next_map(request, state, current);
#endif
        }
 
        if (fr_type_is_leaf(tmpl_attr_tail_da(current->lhs.vpt)->type)) {
                if (apply_edits_to_leaf(request, state, current) < 0) return -1;
        } else {
                fr_assert(fr_type_is_structural(tmpl_attr_tail_da(current->lhs.vpt)->type));
 
                if (apply_edits_to_list(request, state, current) < 0) return -1;
        }
 
        return next_map(request, state, current);
}
 
/*
 *      The RHS map is a sublist.  Go expand that by creating a child expansion context, and returning to the
 *      main loop.
 */
static int expand_rhs_list(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        map_t const *map = current->map;
        edit_map_t *child;
 
        XDEBUG("%s map %s %s ...", __FUNCTION__, map->lhs->name, fr_tokens[map->op]);
 
        /*
         *      If there's no RHS tmpl, then the RHS is a child list.
         */
        fr_assert(!map->rhs);
 
        /*
         *      Fast path: child is empty, we don't need to do anything.
         */
        if (fr_dlist_empty(&map->child.head)) {
                if (fr_type_is_leaf(tmpl_attr_tail_da(current->lhs.vpt)->type) && (map->op != T_OP_SET)) {
                        REDEBUG("%s[%d] Cannot assign a list to the '%s' data type", MAP_INFO, fr_type_to_str(tmpl_attr_tail_da(current->lhs.vpt)->type));
                        return -1;
                }
 
                return check_rhs(request, state, current);
        }
 
        /*
         *      Allocate a new child structure if necessary.
         */
        child = current->child;
        if (!child) {
                MEM(child = talloc_zero(state, edit_map_t));
                current->child = child;
                child->parent = current;
        }
 
        /*
         *      Initialize the child structure.  There's no edit list here, as we're
         *      creating a temporary pair list.  Any edits to this list aren't
         *      tracked, as it only exists in current->parent->rhs.pair_list.
         *
         *      The parent edit_state_t will take care of applying any edits to the
         *      parent vp.  Any child pairs which aren't used will be freed.
         */
        child->el = NULL;
        child->map_list = &map->child;
        child->map = map_list_head(child->map_list);
        child->func = expand_lhs;
 
        if (fr_type_is_leaf(tmpl_attr_tail_da(current->lhs.vpt)->type)) {
                child->ctx = child;
                child->check_lhs = check_lhs_value;
                child->expanded_lhs = expanded_lhs_value;
        } else {
                fr_assert(fr_type_is_structural(tmpl_attr_tail_da(current->lhs.vpt)->type));
 
                child->ctx = current->lhs.vp ? (TALLOC_CTX *) current->lhs.vp : (TALLOC_CTX *) child;
                child->check_lhs = check_lhs_nested;
                child->expanded_lhs = expanded_lhs_attribute;
                child->temporary_pair_list = true;
        }
 
        memset(&child->lhs, 0, sizeof(child->lhs));
        memset(&child->rhs, 0, sizeof(child->rhs));
 
        fr_pair_list_init(&child->rhs.pair_list);
        fr_value_box_list_init(&child->lhs.result);
        fr_value_box_list_init(&child->rhs.result);
 
        /*
         *      Continue back with the RHS when we're done processing the
         *      child.  The go process the child.
         */
        current->func = check_rhs;
        state->current = child;
        RINDENT();
        return 0;
}
 
 
/*
 *      Expand the RHS of an assignment operation.
 */
static int expand_rhs(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        int rcode;
        map_t const *map = current->map;
 
        if (!map->rhs) return expand_rhs_list(request, state, current);
 
        XDEBUG("%s map %s %s %s", __FUNCTION__, map->lhs->name, fr_tokens[map->op], map->rhs->name);
 
        /*
         *      Turn the RHS into a tmpl_t.  This can involve just referencing an existing
         *      tmpl in map->rhs, or expanding an xlat to get an attribute name.
         */
        rcode = tmpl_to_values(state, &current->rhs, request, map->rhs);
        if (rcode < 0) return -1;
 
        if (rcode == 1) {
                current->func = check_rhs;
                return 1;
        }
 
        return check_rhs(request, state, current);
}
 
/*
 *      The LHS is a value, and the parent is a leaf.  There is no RHS.
 *
 *      Do some validations, and move the value-boxes to the parents result list.
 */
static int check_lhs_value(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        map_t const             *map = current->map;
        fr_value_box_t          *box;
        fr_pair_t               *vp;
        tmpl_t const            *vpt;
        tmpl_dcursor_ctx_t      cc;
        fr_dcursor_t            cursor;
 
        fr_assert(current->parent);
 
        XDEBUG("%s map %s", __FUNCTION__, map->lhs->name);
 
        if (tmpl_is_data(map->lhs)) {
                vpt = map->lhs;
 
        data:
                MEM(box = fr_value_box_alloc_null(state));
                if (fr_value_box_copy(box, box, tmpl_value(vpt)) < 0) return -1;
 
                fr_value_box_list_insert_tail(&current->parent->rhs.result, box);
 
                return next_map(request, state, current);
        }
 
        if (!current->lhs.vpt) {
                vpt = map->lhs;
 
                /*
                 *
                 */
                if (tmpl_is_xlat(vpt)) return next_map(request,state, current);
 
        attr:
                fr_assert(tmpl_is_attr(vpt));
 
                /*
                 *      Loop over the attributes, copying their value-boxes to the parent list.
                 */
                vp = tmpl_dcursor_init(NULL, request, &cc, &cursor, request, vpt);
                while (vp) {
                        MEM(box = fr_value_box_alloc_null(state));
                        if (fr_value_box_copy(box, box, &vp->data) < 0) return -1;
 
                        fr_value_box_list_insert_tail(&current->parent->rhs.result, box);
 
                        vp = fr_dcursor_next(&cursor);
                }
                tmpl_dcursor_clear(&cc);
 
                return next_map(request, state, current);
        }
 
        vpt = current->lhs.vpt;
 
        if (tmpl_is_data(vpt)) goto data;
 
        goto attr;
}
 
/*
 *      We've expanded the LHS (xlat or exec) into a value-box list.  The result gets moved to the parent
 *      result list.
 *
 *      There's no RHS, so once the LHS has been expanded, we jump immediately to the next entry.
 */
static int expanded_lhs_value(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        fr_dict_attr_t const *da;
        fr_type_t type;
        fr_value_box_t *box = fr_value_box_list_head(&current->lhs.result);
        fr_value_box_t *dst;
        fr_sbuff_unescape_rules_t *erules = NULL;
 
        fr_assert(current->parent);
 
        if (!box) {
                RWDEBUG("Failed expanding result");
                return -1;
        }
 
        fr_assert(tmpl_is_attr(current->parent->lhs.vpt));
 
        /*
         *      There's only one value-box, just use it as-is.  We let the parent handler complain about being
         *      able to parse (or not) the value.
         */
        if (!fr_value_box_list_next(&current->lhs.result, box)) goto done;
 
        /*
         *      Figure out how to parse the string.
         */
        da = tmpl_attr_tail_da(current->parent->lhs.vpt);
        if (fr_type_is_structural(da->type)) {
                fr_assert(da->type == FR_TYPE_GROUP);
 
                type = FR_TYPE_STRING;
 
        } else if (fr_type_is_variable_size(da->type)) {
                type = da->type;
 
        } else {
                type = FR_TYPE_STRING;
        }
 
        /*
         *      Mash all of the results together.
         */
        if (fr_value_box_list_concat_in_place(box, box, &current->lhs.result, type, FR_VALUE_BOX_LIST_FREE, true, SIZE_MAX) < 0) {
                RWDEBUG("Failed converting result to '%s' - no memory", fr_type_to_str(type));
                return -1;
        }
 
        /*
         *      Strings, etc. get assigned to the parent.  Fixed-size things ger parsed according to their values / enums.
         */
        if (!fr_type_is_fixed_size(da->type)) {
        done:
                fr_value_box_list_move(&current->parent->rhs.result, &current->lhs.result);
                return next_map(request, state, current);
        }
 
        /*
         *      Try to re-parse the box as the destination data type.
         */
        MEM(dst = fr_value_box_alloc(state, type, da));
 
        erules = fr_value_unescape_by_quote[current->map->lhs->quote];
 
        if (fr_value_box_from_str(dst, dst, da->type, da, box->vb_strvalue, box->vb_length, erules) < 0) {
                RWDEBUG("Failed converting result to '%s' - %s", fr_type_to_str(type), fr_strerror());
                return -1;
        }
        fr_value_box_safety_copy_changed(dst, box);
 
        fr_value_box_list_talloc_free(&current->lhs.result);
        fr_value_box_list_insert_tail(&current->parent->rhs.result, dst);
        return next_map(request, state, current);
}
 
/*
 *      Check the LHS of an assignment, for
 *
 *              foo = { bar = baz }     LHS bar
 *
 *      There are more limitations here on the attr / op / value format then for the top-level check_lhs().
 */
static int check_lhs_nested(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        map_t const *map = current->map;
 
        fr_assert(current->parent != NULL);
 
        XDEBUG("%s map %s", __FUNCTION__, map->lhs->name);
 
        /*
         *      Don't create the leaf.  The apply_edits_to_leaf() function will create them after the RHS has
         *      been expanded.
         */
        if (fr_type_is_leaf(tmpl_attr_tail_da(current->lhs.vpt)->type)) {
                return expand_rhs(request, state, current);
        }
 
        fr_assert(fr_type_is_structural(tmpl_attr_tail_da(current->lhs.vpt)->type));
 
        /*
         *      We have a parent, so we know that attribute exist.  Which means that we don't need to call a
         *      cursor function to create this VP.
         */
 
        /*
         *      We create this VP in the "current" context, so that it's freed on
         *      error.  If we create it in the LHS VP context, then we have to
         *      manually free rhs.pair_list on any error.  Creating it in the
         *      "current" context means we have to reparent it when we move it to the
         *      parent list, but fr_edit_list_apply_list_assignment() does that
         *      anyways.
         */
        MEM(current->lhs.vp = fr_pair_afrom_da(current->ctx, tmpl_attr_tail_da(current->lhs.vpt)));
        fr_pair_append(&current->parent->rhs.pair_list, current->lhs.vp);
        current->lhs.vp->op = map->op;
 
        return expand_rhs(request, state, current);
}
 
/*
 *      The LHS tmpl is now an attribute reference.  Do some sanity checks on tmpl_attr_tail_num(), operators, etc.
 *      Once that's done, go expand the RHS.
 */
static int check_lhs(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        map_t const *map = current->map;
        int                     err;
        fr_pair_t               *vp;
        tmpl_dcursor_ctx_t      cc;
        fr_dcursor_t            cursor;
 
        current->lhs.create = false;
        current->lhs.vp = NULL;
 
        XDEBUG("%s map %s %s ...", __FUNCTION__, map->lhs->name, fr_tokens[map->op]);
 
        /*
         *      Create the attribute, including any necessary parents.
         */
        if ((map->op == T_OP_EQ) ||
            (fr_type_is_leaf(tmpl_attr_tail_da(current->lhs.vpt)->type) && fr_comparison_op[map->op])) {
                if (tmpl_attr_tail_num(current->lhs.vpt) == NUM_UNSPEC) {
                        current->lhs.create = true;
 
                        /*
                         *      Don't go to expand_rhs(), as we have to see if the attribute exists.
                         */
                }
 
        } else if (map->op == T_OP_SET) {
                if (tmpl_attr_tail_num(current->lhs.vpt) == NUM_UNSPEC) {
                        current->lhs.create = true;
                        return expand_rhs(request, state, current);
                }
 
                /*
                 *      Else we're doing something like:
                 *
                 *              &foo[1] := bar
                 *
                 *      the attribute has to exist, and we modify its value as a leaf.
                 *
                 *      If the RHS is a list, we can set the children for a LHS structural type.
                 *      But if the LHS is a leaf, then we can't do:
                 *
                 *              &foo[3] := { a, b, c}
                 *
                 *      because foo[3] is a single leaf value, not a list.
                 */
                if (!map->rhs && fr_type_is_leaf(tmpl_attr_tail_da(current->lhs.vpt)->type) &&
                    (map_list_num_elements(&map->child) > 0)) {
                        RWDEBUG("Cannot set one entry to multiple values for %s", current->lhs.vpt->name);
                        return -1;
                }
 
        } else if (map->op == T_OP_ADD_EQ) {
                /*
                 *      For "+=", if there's no existing attribute, create one, and rewrite the operator we
                 *      apply to ":=".  Which also means moving the operator be in edit_map_t, and then updating the
                 *      "apply" functions above to use that for the operations, but map->op for printing.
                 *
                 *      This allows "foo += 4" to set "foo := 4" when the attribute doesn't exist.  It also allows us
                 *      to do list appending to an empty list.  But likely only for strings, octets, and numbers.
                 *      Nothing much else makes sense.
                 */
 
                switch (tmpl_attr_tail_da(current->lhs.vpt)->type) {
                case FR_TYPE_NUMERIC:
                case FR_TYPE_OCTETS:
                case FR_TYPE_STRING:
                case FR_TYPE_STRUCTURAL:
                        current->lhs.create = true;
                        break;
 
                default:
                        break;
                }
        }
 
        /*
         *      Find the VP.  If the operation is "=" or ":=", then it's OK for the VP to not exist.
         *
         *      @todo - put the cursor into the LHS, and then set lhs.vp == NULL
         *      use the cursor in apply_edits_to_leaf()
         */
        fr_strerror_clear();
        vp = tmpl_dcursor_init(&err, current->ctx, &cc, &cursor, request, current->lhs.vpt);
        tmpl_dcursor_clear(&cc);
        if (!vp) {
                if (!current->lhs.create) {
                        RWDEBUG("Failed finding %s", current->lhs.vpt->name);
                        return -1;
                }
 
                /*
                 *      Else we need to create it.
                 */
                return expand_rhs(request, state, current);
 
        } else if (current->lhs.create) {
                /*
                 *      &foo[1] := bar
                 *      &foo = bar
                 */
                current->lhs.create = false;
 
                if (map->rhs && fr_type_is_structural(vp->vp_type) && tmpl_is_exec(map->rhs)) {
                        int rcode;
 
                        current->lhs.vp = vp;
                        current->lhs.vp_parent = fr_pair_parent(vp);
 
                        rcode = tmpl_to_values(state, &current->rhs, request, map->rhs);
                        if (rcode < 0) return -1;
 
                        if (rcode == 1) {
                                current->func = check_rhs;
                                return 1;
                        }
 
                        return expand_rhs(request, state, current);
                }
 
                /*
                 *      We found it, but the attribute already exists.  This
                 *      is a NOOP, where we ignore this assignment.
                 */
                if (map->op == T_OP_EQ) {
                        return next_map(request, state, current);
                }
 
                /*
                 *      &foo[1] exists, don't bother deleting it.  Just over-write its value.
                 */
                fr_assert((map->op == T_OP_SET) || (map->op == T_OP_ADD_EQ) || fr_comparison_op[map->op]);
//              fr_assert((map->op == T_OP_ADD_EQ) || tmpl_attr_tail_num(map->lhs) != NUM_UNSPEC);
 
                // &control := ...
        }
 
        /*
         *      We forbid operations on immutable leaf attributes.
         *
         *      If a list contains an immutable attribute, then we can still operate on the list, but instead
         *      we look at each VP we're operating on.
         */
        if (fr_type_is_leaf(vp->vp_type) && vp->vp_immutable) {
                RWDEBUG("Cannot modify immutable value for %s", current->lhs.vpt->name);
                return -1;
        }
 
        /*
         *      We found an existing attribute, with a modification operator.
         */
        current->lhs.vp = vp;
        current->lhs.vp_parent = fr_pair_parent(current->lhs.vp);
        return expand_rhs(request, state, current);
}
 
/*
 *      We've expanding the LHS into a string.  Now convert it to an attribute.
 *
 *              foo := bar              LHS foo
 *              foo = { bar = baz }     LHS bar
 */
static int expanded_lhs_attribute(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        REXDENT();
 
        if (tmpl_attr_from_result(state, current->map, &current->lhs, request) < 0) return -1;
 
        return current->check_lhs(request, state, current);
}
 
/*
 *      Take the LHS of a map, and figure out what it is.  Data and attributes are immediately processed.
 *      xlats and execs are expanded, and then their expansion is checked.
 *
 *      This function is called for all variants of the LHS:
 *
 *              foo := bar              LHS foo
 *              foo = { bar = baz }     LHS bar
 *              foo = { 1, 2, 3, 4 }    LHS 1, 2, etc.
 *
 */
static int expand_lhs(request_t *request, unlang_frame_state_edit_t *state, edit_map_t *current)
{
        int rcode;
        map_t const *map = current->map;
 
        XDEBUG("%s map %s %s ...", __FUNCTION__, map->lhs->name, fr_tokens[map->op]);
 
        fr_assert(fr_value_box_list_empty(&current->lhs.result));       /* Should have been consumed */
        fr_assert(fr_value_box_list_empty(&current->rhs.result));       /* Should have been consumed */
 
        rcode = tmpl_to_values(state, &current->lhs, request, map->lhs);
        if (rcode < 0) return -1;
 
        if (rcode == 1) {
                current->func = current->expanded_lhs;
                return 1;
        }
 
        return current->check_lhs(request, state, current);
}
 
/** Apply a map (recursively) to a request.
 *
 * @param[out] p_result The rcode indicating what the result
 *                      of the operation was.
 * @param[in] request   The current request.
 * @param[in] frame     Current stack frame.
 * @return
 *      - UNLANG_ACTION_CALCULATE_RESULT changes were applied.
 *      - UNLANG_ACTION_PUSHED_CHILD async execution of an expansion is required.
 */
static unlang_action_t process_edit(rlm_rcode_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_frame_state_edit_t       *state = talloc_get_type_abort(frame->state, unlang_frame_state_edit_t);
 
        /*
         *      Keep running the "expand map" function until done.
         */
        while (state->current) {
                while (state->current->map) {
                        int rcode;
 
                        if (!state->current->map->rhs) {
                                XDEBUG("MAP %s ...", state->current->map->lhs->name);
                        } else {
                                XDEBUG("MAP %s ... %s", state->current->map->lhs->name, state->current->map->rhs->name);
                        }
 
                        rcode = state->current->func(request, state, state->current);
                        if (rcode < 0) {
                                RINDENT_RESTORE(request, state);
 
                                /*
                                 *      Expansions, etc. failures are SOFT failures, which undo the edit
                                 *      operations, but otherwise do not affect the interpreter.
                                 *
                                 *      However, if the caller asked for the actual result, return that, too.
                                 */
                                if (state->success) *state->success = false;
 
                                if (state->ours) fr_edit_list_abort(state->el);
                                TALLOC_FREE(frame->state);
                                repeatable_clear(frame);
                                *p_result = RLM_MODULE_FAIL;
 
                                return UNLANG_ACTION_CALCULATE_RESULT;
                        }
 
                        if (rcode == 1) {
                                repeatable_set(frame);
                                return UNLANG_ACTION_PUSHED_CHILD;
                        }
                }
 
                /*
                 *      Stop if there's no parent to process.
                 */
                if (!state->current->parent) break;
 
                state->current = state->current->parent;
                REXDENT();      /* "push child" has called RINDENT */
        }
 
        /*
         *      Freeing the edit list will automatically commit the edits.  i.e. trash the undo list, and
         *      leave the edited pairs in place.
         */
 
        RINDENT_RESTORE(request, state);
 
        *p_result = RLM_MODULE_NOOP;
        if (state->success) *state->success = true;
        return UNLANG_ACTION_CALCULATE_RESULT;
}
 
static void edit_state_init_internal(request_t *request, unlang_frame_state_edit_t *state, fr_edit_list_t *el, map_list_t const *map_list)
{
        edit_map_t                      *current = &state->first;
 
        state->current = current;
        fr_value_box_list_init(&current->lhs.result);
        fr_value_box_list_init(&current->rhs.result);
 
        /*
         *      The edit list creates a local pool which should
         *      generally be large enough for most edits.
         */
        if (!el) {
                MEM(state->el = fr_edit_list_alloc(state, map_list_num_elements(map_list), NULL));
                state->ours = true;
        } else {
                state->el = el;
                state->ours = false;
        }
 
        current->ctx = state;
        current->el = state->el;
        current->map_list = map_list;
        current->map = map_list_head(current->map_list);
        fr_pair_list_init(&current->rhs.pair_list);
        current->func = expand_lhs;
        current->check_lhs = check_lhs;
        current->expanded_lhs = expanded_lhs_attribute;
 
        /*
         *      Save current indentation for the error path.
         */
        RINDENT_SAVE(state, request);
}
 
/** Execute an update block
 *
 * Update blocks execute in two phases, first there's an evaluation phase where
 * each input map is evaluated, outputting one or more modification maps. The modification
 * maps detail a change that should be made to a list in the current request.
 * The request is not modified during this phase.
 *
 * The second phase applies those modification maps to the current request.
 * This re-enables the atomic functionality of update blocks provided in v2.x.x.
 * If one map fails in the evaluation phase, no more maps are processed, and the current
 * result is discarded.
 */
static unlang_action_t unlang_edit_state_init(rlm_rcode_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_edit_t                   *edit = unlang_generic_to_edit(frame->instruction);
        unlang_frame_state_edit_t       *state = talloc_get_type_abort(frame->state, unlang_frame_state_edit_t);
        fr_edit_list_t                  *el = unlang_interpret_edit_list(request);
 
        edit_state_init_internal(request, state, el, &edit->maps);
 
        /*
         *      Call process_edit to do all of the work.
         */
        frame_repeat(frame, process_edit);
        return process_edit(p_result, request, frame);
}
 
 
/** Push a map onto the stack for edit evaluation
 *
 *  If the "success" variable returns "false", the caller should call fr_edit_list_abort().
 *
 *  If the "success" variable returns "true", the caller can free the edit list (or rely on talloc to do that)
 *  and the transaction will be finalized.
 *
 * @param[in] request           The current request.
 * @param[out] success          Whether or not the edit succeeded
 * @param[in] el                Edit list which can be used to apply multiple edits
 * @param[in] map_list          The map list to process
 */
int unlang_edit_push(request_t *request, bool *success, fr_edit_list_t *el, map_list_t const *map_list)
{
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame;
        unlang_frame_state_edit_t       *state;
 
        unlang_edit_t                   *edit;
 
        static unlang_t edit_instruction = {
                .type = UNLANG_TYPE_EDIT,
                .name = "edit",
                .debug_name = "edit",
                .actions = {
                        .actions = {
                                [RLM_MODULE_REJECT]     = 0,
                                [RLM_MODULE_FAIL]       = 0,
                                [RLM_MODULE_OK]         = 0,
                                [RLM_MODULE_HANDLED]    = 0,
                                [RLM_MODULE_INVALID]    = 0,
                                [RLM_MODULE_DISALLOW]   = 0,
                                [RLM_MODULE_NOTFOUND]   = 0,
                                [RLM_MODULE_NOOP]       = 0,
                                [RLM_MODULE_UPDATED]    = 0
                        },
                        .retry = RETRY_INIT,
                },
        };
 
        MEM(edit = talloc(stack, unlang_edit_t));
        *edit = (unlang_edit_t) {
                .self = edit_instruction,
        };
        map_list_init(&edit->maps);
 
        /*
         *      Push a new edit frame onto the stack
         */
        if (unlang_interpret_push(request, unlang_edit_to_generic(edit),
                                  RLM_MODULE_NOT_SET, UNLANG_NEXT_STOP, false) < 0) return -1;
 
        frame = &stack->frame[stack->depth];
        state = talloc_get_type_abort(frame->state, unlang_frame_state_edit_t);
 
        edit_state_init_internal(request, state, el, map_list);
        state->success = success;
 
        return 0;
}
 
void unlang_edit_init(void)
{
        unlang_register(UNLANG_TYPE_EDIT,
                           &(unlang_op_t){
                                .name = "edit",
                                .interpret = unlang_edit_state_init,
                                .frame_state_size = sizeof(unlang_frame_state_edit_t),
                                .frame_state_type = "unlang_frame_state_edit_t",
                           });
}