/*
 * libfdt - Flat Device Tree manipulation
 * Copyright (C) 2013 Google, Inc
 * Written by Simon Glass <sjg@chromium.org>
 * SPDX-License-Identifier:     GPL-2.0+ BSD-2-Clause
 */

#include <libfdt_env.h>

#ifndef USE_HOSTCC
#include <fdt.h>
#include <libfdt.h>
#else
#include "fdt_host.h"
#endif

#include "libfdt_internal.h"

/**
 * fdt_add_region() - Add a new region to our list
 * @info:       State information
 * @offset:     Start offset of region
 * @size:       Size of region
 *
 * The region is added if there is space, but in any case we increment the
 * count. If permitted, and the new region overlaps the last one, we merge
 * them.
 */
static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
{
        struct fdt_region *reg;

        reg = info->region ? &info->region[info->count - 1] : NULL;
        if (info->can_merge && info->count &&
            info->count <= info->max_regions &&
            reg && offset <= reg->offset + reg->size) {
                reg->size = offset + size - reg->offset;
        } else if (info->count++ < info->max_regions) {
                if (reg) {
                        reg++;
                        reg->offset = offset;
                        reg->size = size;
                }
        } else {
                return -1;
        }

        return 0;
}

static int region_list_contains_offset(struct fdt_region_state *info,
                                       const void *fdt, int target)
{
        struct fdt_region *reg;
        int num;

        target += fdt_off_dt_struct(fdt);
        for (reg = info->region, num = 0; num < info->count; reg++, num++) {
                if (target >= reg->offset && target < reg->offset + reg->size)
                        return 1;
        }

        return 0;
}

int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
                          int max_regions, struct fdt_region_state *info)
{
        int base = fdt_off_dt_struct(fdt);
        int node, node_end, offset;
        int did_alias_header;

        node = fdt_subnode_offset(fdt, 0, "aliases");
        if (node < 0)
                return -FDT_ERR_NOTFOUND;

        /* The aliases node must come before the others */
        node_end = fdt_next_subnode(fdt, node);
        if (node_end <= 0)
                return -FDT_ERR_BADLAYOUT;
        node_end -= sizeof(fdt32_t);

        did_alias_header = 0;
        info->region = region;
        info->count = count;
        info->can_merge = 0;
        info->max_regions = max_regions;

        for (offset = fdt_first_property_offset(fdt, node);
             offset >= 0;
             offset = fdt_next_property_offset(fdt, offset)) {
                const struct fdt_property *prop;
                const char *name;
                int target, next;

                prop = fdt_get_property_by_offset(fdt, offset, NULL);
                name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
                target = fdt_path_offset(fdt, name);
                if (!region_list_contains_offset(info, fdt, target))
                        continue;
                next = fdt_next_property_offset(fdt, offset);
                if (next < 0)
                        next = node_end;

                if (!did_alias_header) {
                        fdt_add_region(info, base + node, 12);
                        did_alias_header = 1;
                }
                fdt_add_region(info, base + offset, next - offset);
        }

        /* Add the 'end' tag */
        if (did_alias_header)
                fdt_add_region(info, base + node_end, sizeof(fdt32_t));

        return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
}

/**
 * fdt_include_supernodes() - Include supernodes required by this node
 * @info:       State information
 * @depth:      Current stack depth
 *
 * When we decided to include a node or property which is not at the top
 * level, this function forces the inclusion of higher level nodes. For
 * example, given this tree:
 *
 * / {
 *     testing {
 *     }
 * }
 *
 * If we decide to include testing then we need the root node to have a valid
 * tree. This function adds those regions.
 */
static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
{
        int base = fdt_off_dt_struct(info->fdt);
        int start, stop_at;
        int i;

        /*
         * Work down the stack looking for supernodes that we didn't include.
         * The algortihm here is actually pretty simple, since we know that
         * no previous subnode had to include these nodes, or if it did, we
         * marked them as included (on the stack) already.
         */
        for (i = 0; i <= depth; i++) {
                if (!info->stack[i].included) {
                        start = info->stack[i].offset;

                        /* Add the FDT_BEGIN_NODE tag of this supernode */
                        fdt_next_tag(info->fdt, start, &stop_at);
                        if (fdt_add_region(info, base + start, stop_at - start))
                                return -1;

                        /* Remember that this supernode is now included */
                        info->stack[i].included = 1;
                        info->can_merge = 1;
                }

                /* Force (later) generation of the FDT_END_NODE tag */
                if (!info->stack[i].want)
                        info->stack[i].want = WANT_NODES_ONLY;
        }

        return 0;
}

enum {
        FDT_DONE_NOTHING,
        FDT_DONE_MEM_RSVMAP,
        FDT_DONE_STRUCT,
        FDT_DONE_END,
        FDT_DONE_STRINGS,
        FDT_DONE_ALL,
};

int fdt_first_region(const void *fdt,
                int (*h_include)(void *priv, const void *fdt, int offset,
                                 int type, const char *data, int size),
                void *priv, struct fdt_region *region,
                char *path, int path_len, int flags,
                struct fdt_region_state *info)
{
        struct fdt_region_ptrs *p = &info->ptrs;

        /* Set up our state */
        info->fdt = fdt;
        info->can_merge = 1;
        info->max_regions = 1;
        info->start = -1;
        p->want = WANT_NOTHING;
        p->end = path;
        *p->end = '\0';
        p->nextoffset = 0;
        p->depth = -1;
        p->done = FDT_DONE_NOTHING;

        return fdt_next_region(fdt, h_include, priv, region,
                               path, path_len, flags, info);
}

/***********************************************************************
 *
 *      Theory of operation
 *
 * Note: in this description 'included' means that a node (or other part
 * of the tree) should be included in the region list, i.e. it will have
 * a region which covers its part of the tree.
 *
 * This function maintains some state from the last time it is called.
 * It checks the next part of the tree that it is supposed to look at
 * (p.nextoffset) to see if that should be included or not. When it
 * finds something to include, it sets info->start to its offset. This
 * marks the start of the region we want to include.
 *
 * Once info->start is set to the start (i.e. not -1), we continue
 * scanning until we find something that we don't want included. This
 * will be the end of a region. At this point we can close off the
 * region and add it to the list. So we do so, and reset info->start
 * to -1.
 *
 * One complication here is that we want to merge regions. So when we
 * come to add another region later, we may in fact merge it with the
 * previous one if one ends where the other starts.
 *
 * The function fdt_add_region() will return -1 if it fails to add the
 * region, because we already have a region ready to be returned, and
 * the new one cannot be merged in with it. In this case, we must return
 * the region we found, and wait for another call to this function.
 * When it comes, we will repeat the processing of the tag and again
 * try to add a region. This time it will succeed.
 *
 * The current state of the pointers (stack, offset, etc.) is maintained
 * in a ptrs member. At the start of every loop iteration we make a copy
 * of it.  The copy is then updated as the tag is processed. Only if we
 * get to the end of the loop iteration (and successfully call
 * fdt_add_region() if we need to) can we commit the changes we have
 * made to these pointers. For example, if we see an FDT_END_NODE tag,
 * we will decrement the depth value. But if we need to add a region
 * for this tag (let's say because the previous tag is included and this
 * FDT_END_NODE tag is not included) then we will only commit the result
 * if we were able to add the region. That allows us to retry again next
 * time.
 *
 * We keep track of a variable called 'want' which tells us what we want
 * to include when there is no specific information provided by the
 * h_include function for a particular property. This basically handles
 * the inclusion of properties which are pulled in by virtue of the node
 * they are in. So if you include a node, its properties are also
 * included.  In this case 'want' will be WANT_NODES_AND_PROPS. The
 * FDT_REG_DIRECT_SUBNODES feature also makes use of 'want'. While we
 * are inside the subnode, 'want' will be set to WANT_NODES_ONLY, so
 * that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE tags will be
 * included, and properties will be skipped. If WANT_NOTHING is
 * selected, then we will just rely on what the h_include() function
 * tells us.
 *
 * Using 'want' we work out 'include', which tells us whether this
 * current tag should be included or not. As you can imagine, if the
 * value of 'include' changes, that means we are on a boundary between
 * nodes to include and nodes to exclude. At this point we either close
 * off a previous region and add it to the list, or mark the start of a
 * new region.
 *
 * Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the
 * string list. Each of these dealt with as a whole (i.e. we create a
 * region for each if it is to be included). For mem_rsvmap we don't
 * allow it to merge with the first struct region. For the stringlist,
 * we don't allow it to merge with the last struct region (which
 * contains at minimum the FDT_END tag).
 *
 *********************************************************************/

int fdt_next_region(const void *fdt,
                int (*h_include)(void *priv, const void *fdt, int offset,
                                 int type, const char *data, int size),
                void *priv, struct fdt_region *region,
                char *path, int path_len, int flags,
                struct fdt_region_state *info)
{
        int base = fdt_off_dt_struct(fdt);
        int last_node = 0;
        const char *str;

        info->region = region;
        info->count = 0;
        if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
            (flags & FDT_REG_ADD_MEM_RSVMAP)) {
                /* Add the memory reserve map into its own region */
                if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
                                   fdt_off_dt_struct(fdt) -
                                   fdt_off_mem_rsvmap(fdt)))
                        return 0;
                info->can_merge = 0;    /* Don't allow merging with this */
                info->ptrs.done = FDT_DONE_MEM_RSVMAP;
        }

        /*
         * Work through the tags one by one, deciding whether each needs to
         * be included or not. We set the variable 'include' to indicate our
         * decision. 'want' is used to track what we want to include - it
         * allows us to pick up all the properties (and/or subnode tags) of
         * a node.
         */
        while (info->ptrs.done < FDT_DONE_STRUCT) {
                const struct fdt_property *prop;
                struct fdt_region_ptrs p;
                const char *name;
                int include = 0;
                int stop_at = 0;
                uint32_t tag;
                int offset;
                int val;
                int len;

                /*
                 * Make a copy of our pointers. If we make it to the end of
                 * this block then we will commit them back to info->ptrs.
                 * Otherwise we can try again from the same starting state
                 * next time we are called.
                 */
                p = info->ptrs;

                /*
                 * Find the tag, and the offset of the next one. If we need to
                 * stop including tags, then by default we stop *after*
                 * including the current tag
                 */
                offset = p.nextoffset;
                tag = fdt_next_tag(fdt, offset, &p.nextoffset);
                stop_at = p.nextoffset;

                switch (tag) {
                case FDT_PROP:
                        stop_at = offset;
                        prop = fdt_get_property_by_offset(fdt, offset, NULL);
                        str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
                        val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
                                            strlen(str) + 1);
                        if (val == -1) {
                                include = p.want >= WANT_NODES_AND_PROPS;
                        } else {
                                include = val;
                                /*
                                 * Make sure we include the } for this block.
                                 * It might be more correct to have this done
                                 * by the call to fdt_include_supernodes() in
                                 * the case where it adds the node we are
                                 * currently in, but this is equivalent.
                                 */
                                if ((flags & FDT_REG_SUPERNODES) && val &&
                                    !p.want)
                                        p.want = WANT_NODES_ONLY;
                        }

                        /* Value grepping is not yet supported */
                        break;

                case FDT_NOP:
                        include = p.want >= WANT_NODES_AND_PROPS;
                        stop_at = offset;
                        break;

                case FDT_BEGIN_NODE:
                        last_node = offset;
                        p.depth++;
                        if (p.depth == FDT_MAX_DEPTH)
                                return -FDT_ERR_TOODEEP;
                        name = fdt_get_name(fdt, offset, &len);
                        if (p.end - path + 2 + len >= path_len)
                                return -FDT_ERR_NOSPACE;

                        /* Build the full path of this node */
                        if (p.end != path + 1)
                                *p.end++ = '/';
                        strcpy(p.end, name);
                        p.end += len;
                        info->stack[p.depth].want = p.want;
                        info->stack[p.depth].offset = offset;

                        /*
                         * If we are not intending to include this node unless
                         * it matches, make sure we stop *before* its tag.
                         */
                        if (p.want == WANT_NODES_ONLY ||
                            !(flags & (FDT_REG_DIRECT_SUBNODES |
                                       FDT_REG_ALL_SUBNODES))) {
                                stop_at = offset;
                                p.want = WANT_NOTHING;
                        }
                        val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
                                        p.end - path + 1);

                        /* Include this if requested */
                        if (val) {
                                p.want = (flags & FDT_REG_ALL_SUBNODES) ?
                                        WANT_ALL_NODES_AND_PROPS :
                                        WANT_NODES_AND_PROPS;
                        }

                        /* If not requested, decay our 'p.want' value */
                        else if (p.want) {
                                if (p.want != WANT_ALL_NODES_AND_PROPS)
                                        p.want--;

                        /* Not including this tag, so stop now */
                        } else {
                                stop_at = offset;
                        }

                        /*
                         * Decide whether to include this tag, and update our
                         * stack with the state for this node
                         */
                        include = p.want;
                        info->stack[p.depth].included = include;
                        break;

                case FDT_END_NODE:
                        include = p.want;
                        if (p.depth < 0)
                                return -FDT_ERR_BADSTRUCTURE;

                        /*
                         * If we don't want this node, stop right away, unless
                         * we are including subnodes
                         */
                        if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
                                stop_at = offset;
                        p.want = info->stack[p.depth].want;
                        p.depth--;
                        while (p.end > path && *--p.end != '/')
                                ;
                        *p.end = '\0';
                        break;

                case FDT_END:
                        /* We always include the end tag */
                        include = 1;
                        p.done = FDT_DONE_STRUCT;
                        break;
                }

                /* If this tag is to be included, mark it as region start */
                if (include && info->start == -1) {
                        /* Include any supernodes required by this one */
                        if (flags & FDT_REG_SUPERNODES) {
                                if (fdt_include_supernodes(info, p.depth))
                                        return 0;
                        }
                        info->start = offset;
                }

                /*
                 * If this tag is not to be included, finish up the current
                 * region.
                 */
                if (!include && info->start != -1) {
                        if (fdt_add_region(info, base + info->start,
                                           stop_at - info->start))
                                return 0;
                        info->start = -1;
                        info->can_merge = 1;
                }

                /* If we have made it this far, we can commit our pointers */
                info->ptrs = p;
        }

        /* Add a region for the END tag and a separate one for string table */
        if (info->ptrs.done < FDT_DONE_END) {
                if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
                        return -FDT_ERR_BADSTRUCTURE;

                if (fdt_add_region(info, base + info->start,
                                   info->ptrs.nextoffset - info->start))
                        return 0;
                info->ptrs.done++;
        }
        if (info->ptrs.done < FDT_DONE_STRINGS) {
                if (flags & FDT_REG_ADD_STRING_TAB) {
                        info->can_merge = 0;
                        if (fdt_off_dt_strings(fdt) <
                            base + info->ptrs.nextoffset)
                                return -FDT_ERR_BADLAYOUT;
                        if (fdt_add_region(info, fdt_off_dt_strings(fdt),
                                           fdt_size_dt_strings(fdt)))
                                return 0;
                }
                info->ptrs.done++;
        }

        return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;
}