source: rtems/cpukit/dtc/libfdt/fdt_ro.c @ 78ad048

/*
 * libfdt - Flat Device Tree manipulation
 * Copyright (C) 2006 David Gibson, IBM Corporation.
 *
 * libfdt is dual licensed: you can use it either under the terms of
 * the GPL, or the BSD license, at your option.
 *
 *  a) This library 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 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 General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public
 *     License along with this library; if not, write to the Free
 *     Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 *     MA 02110-1301 USA
 *
 * Alternatively,
 *
 *  b) Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *     1. Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *     2. Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include "libfdt_env.h"

#include <fdt.h>
#include <libfdt.h>

#include "libfdt_internal.h"

static int fdt_nodename_eq_(const void *fdt, int offset,
                            const char *s, int len)
{
        int olen;
        const char *p = fdt_get_name(fdt, offset, &olen);

        if (!p || olen < len)
                /* short match */
                return 0;

        if (memcmp(p, s, len) != 0)
                return 0;

        if (p[len] == '\0')
                return 1;
        else if (!memchr(s, '@', len) && (p[len] == '@'))
                return 1;
        else
                return 0;
}

const char *fdt_get_string(const void *fdt, int stroffset, int *lenp)
{
        uint32_t absoffset = stroffset + fdt_off_dt_strings(fdt);
        size_t len;
        int err;
        const char *s, *n;

        err = fdt_ro_probe_(fdt);
        if (err != 0)
                goto fail;

        err = -FDT_ERR_BADOFFSET;
        if (absoffset >= fdt_totalsize(fdt))
                goto fail;
        len = fdt_totalsize(fdt) - absoffset;

        if (fdt_magic(fdt) == FDT_MAGIC) {
                if (stroffset < 0)
                        goto fail;
                if (fdt_version(fdt) >= 17) {
                        if (stroffset >= fdt_size_dt_strings(fdt))
                                goto fail;
                        if ((fdt_size_dt_strings(fdt) - stroffset) < len)
                                len = fdt_size_dt_strings(fdt) - stroffset;
                }
        } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
                if ((stroffset >= 0)
                    || (stroffset < -fdt_size_dt_strings(fdt)))
                        goto fail;
                if ((-stroffset) < len)
                        len = -stroffset;
        } else {
                err = -FDT_ERR_INTERNAL;
                goto fail;
        }

        s = (const char *)fdt + absoffset;
        n = memchr(s, '\0', len);
        if (!n) {
                /* missing terminating NULL */
                err = -FDT_ERR_TRUNCATED;
                goto fail;
        }

        if (lenp)
                *lenp = n - s;
        return s;

fail:
        if (lenp)
                *lenp = err;
        return NULL;
}

const char *fdt_string(const void *fdt, int stroffset)
{
        return fdt_get_string(fdt, stroffset, NULL);
}

static int fdt_string_eq_(const void *fdt, int stroffset,
                          const char *s, int len)
{
        int slen;
        const char *p = fdt_get_string(fdt, stroffset, &slen);

        return p && (slen == len) && (memcmp(p, s, len) == 0);
}

uint32_t fdt_get_max_phandle(const void *fdt)
{
        uint32_t max_phandle = 0;
        int offset;

        for (offset = fdt_next_node(fdt, -1, NULL);;
             offset = fdt_next_node(fdt, offset, NULL)) {
                uint32_t phandle;

                if (offset == -FDT_ERR_NOTFOUND)
                        return max_phandle;

                if (offset < 0)
                        return (uint32_t)-1;

                phandle = fdt_get_phandle(fdt, offset);
                if (phandle == (uint32_t)-1)
                        continue;

                if (phandle > max_phandle)
                        max_phandle = phandle;
        }

        return 0;
}

static const struct fdt_reserve_entry *fdt_mem_rsv(const void *fdt, int n)
{
        int offset = n * sizeof(struct fdt_reserve_entry);
        int absoffset = fdt_off_mem_rsvmap(fdt) + offset;

        if (absoffset < fdt_off_mem_rsvmap(fdt))
                return NULL;
        if (absoffset > fdt_totalsize(fdt) - sizeof(struct fdt_reserve_entry))
                return NULL;
        return fdt_mem_rsv_(fdt, n);
}

int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
{
        const struct fdt_reserve_entry *re;

        FDT_RO_PROBE(fdt);
        re = fdt_mem_rsv(fdt, n);
        if (!re)
                return -FDT_ERR_BADOFFSET;

        *address = fdt64_ld(&re->address);
        *size = fdt64_ld(&re->size);
        return 0;
}

int fdt_num_mem_rsv(const void *fdt)
{
        int i;
        const struct fdt_reserve_entry *re;

        for (i = 0; (re = fdt_mem_rsv(fdt, i)) != NULL; i++) {
                if (fdt64_ld(&re->size) == 0)
                        return i;
        }
        return -FDT_ERR_TRUNCATED;
}

static int nextprop_(const void *fdt, int offset)
{
        uint32_t tag;
        int nextoffset;

        do {
                tag = fdt_next_tag(fdt, offset, &nextoffset);

                switch (tag) {
                case FDT_END:
                        if (nextoffset >= 0)
                                return -FDT_ERR_BADSTRUCTURE;
                        else
                                return nextoffset;

                case FDT_PROP:
                        return offset;
                }
                offset = nextoffset;
        } while (tag == FDT_NOP);

        return -FDT_ERR_NOTFOUND;
}

int fdt_subnode_offset_namelen(const void *fdt, int offset,
                               const char *name, int namelen)
{
        int depth;

        FDT_RO_PROBE(fdt);

        for (depth = 0;
             (offset >= 0) && (depth >= 0);
             offset = fdt_next_node(fdt, offset, &depth))
                if ((depth == 1)
                    && fdt_nodename_eq_(fdt, offset, name, namelen))
                        return offset;

        if (depth < 0)
                return -FDT_ERR_NOTFOUND;
        return offset; /* error */
}

int fdt_subnode_offset(const void *fdt, int parentoffset,
                       const char *name)
{
        return fdt_subnode_offset_namelen(fdt, parentoffset, name, strlen(name));
}

int fdt_path_offset_namelen(const void *fdt, const char *path, int namelen)
{
        const char *end = path + namelen;
        const char *p = path;
        int offset = 0;

        FDT_RO_PROBE(fdt);

        /* see if we have an alias */
        if (*path != '/') {
                const char *q = memchr(path, '/', end - p);

                if (!q)
                        q = end;

                p = fdt_get_alias_namelen(fdt, p, q - p);
                if (!p)
                        return -FDT_ERR_BADPATH;
                offset = fdt_path_offset(fdt, p);

                p = q;
        }

        while (p < end) {
                const char *q;

                while (*p == '/') {
                        p++;
                        if (p == end)
                                return offset;
                }
                q = memchr(p, '/', end - p);
                if (! q)
                        q = end;

                offset = fdt_subnode_offset_namelen(fdt, offset, p, q-p);
                if (offset < 0)
                        return offset;

                p = q;
        }

        return offset;
}

int fdt_path_offset(const void *fdt, const char *path)
{
        return fdt_path_offset_namelen(fdt, path, strlen(path));
}

const char *fdt_get_name(const void *fdt, int nodeoffset, int *len)
{
        const struct fdt_node_header *nh = fdt_offset_ptr_(fdt, nodeoffset);
        const char *nameptr;
        int err;

        if (((err = fdt_ro_probe_(fdt)) != 0)
            || ((err = fdt_check_node_offset_(fdt, nodeoffset)) < 0))
                        goto fail;

        nameptr = nh->name;

        if (fdt_version(fdt) < 0x10) {
                /*
                 * For old FDT versions, match the naming conventions of V16:
                 * give only the leaf name (after all /). The actual tree
                 * contents are loosely checked.
                 */
                const char *leaf;
                leaf = strrchr(nameptr, '/');
                if (leaf == NULL) {
                        err = -FDT_ERR_BADSTRUCTURE;
                        goto fail;
                }
                nameptr = leaf+1;
        }

        if (len)
                *len = strlen(nameptr);

        return nameptr;

 fail:
        if (len)
                *len = err;
        return NULL;
}

int fdt_first_property_offset(const void *fdt, int nodeoffset)
{
        int offset;

        if ((offset = fdt_check_node_offset_(fdt, nodeoffset)) < 0)
                return offset;

        return nextprop_(fdt, offset);
}

int fdt_next_property_offset(const void *fdt, int offset)
{
        if ((offset = fdt_check_prop_offset_(fdt, offset)) < 0)
                return offset;

        return nextprop_(fdt, offset);
}

static const struct fdt_property *fdt_get_property_by_offset_(const void *fdt,
                                                              int offset,
                                                              int *lenp)
{
        int err;
        const struct fdt_property *prop;

        if ((err = fdt_check_prop_offset_(fdt, offset)) < 0) {
                if (lenp)
                        *lenp = err;
                return NULL;
        }

        prop = fdt_offset_ptr_(fdt, offset);

        if (lenp)
                *lenp = fdt32_ld(&prop->len);

        return prop;
}

const struct fdt_property *fdt_get_property_by_offset(const void *fdt,
                                                      int offset,
                                                      int *lenp)
{
        /* Prior to version 16, properties may need realignment
         * and this API does not work. fdt_getprop_*() will, however. */

        if (fdt_version(fdt) < 0x10) {
                if (lenp)
                        *lenp = -FDT_ERR_BADVERSION;
                return NULL;
        }

        return fdt_get_property_by_offset_(fdt, offset, lenp);
}

static const struct fdt_property *fdt_get_property_namelen_(const void *fdt,
                                                            int offset,
                                                            const char *name,
                                                            int namelen,
                                                            int *lenp,
                                                            int *poffset)
{
        for (offset = fdt_first_property_offset(fdt, offset);
             (offset >= 0);
             (offset = fdt_next_property_offset(fdt, offset))) {
                const struct fdt_property *prop;

                if (!(prop = fdt_get_property_by_offset_(fdt, offset, lenp))) {
                        offset = -FDT_ERR_INTERNAL;
                        break;
                }
                if (fdt_string_eq_(fdt, fdt32_ld(&prop->nameoff),
                                   name, namelen)) {
                        if (poffset)
                                *poffset = offset;
                        return prop;
                }
        }

        if (lenp)
                *lenp = offset;
        return NULL;
}


const struct fdt_property *fdt_get_property_namelen(const void *fdt,
                                                    int offset,
                                                    const char *name,
                                                    int namelen, int *lenp)
{
        /* Prior to version 16, properties may need realignment
         * and this API does not work. fdt_getprop_*() will, however. */
        if (fdt_version(fdt) < 0x10) {
                if (lenp)
                        *lenp = -FDT_ERR_BADVERSION;
                return NULL;
        }

        return fdt_get_property_namelen_(fdt, offset, name, namelen, lenp,
                                         NULL);
}


const struct fdt_property *fdt_get_property(const void *fdt,
                                            int nodeoffset,
                                            const char *name, int *lenp)
{
        return fdt_get_property_namelen(fdt, nodeoffset, name,
                                        strlen(name), lenp);
}

const void *fdt_getprop_namelen(const void *fdt, int nodeoffset,
                                const char *name, int namelen, int *lenp)
{
        int poffset;
        const struct fdt_property *prop;

        prop = fdt_get_property_namelen_(fdt, nodeoffset, name, namelen, lenp,
                                         &poffset);
        if (!prop)
                return NULL;

        /* Handle realignment */
        if (fdt_version(fdt) < 0x10 && (poffset + sizeof(*prop)) % 8 &&
            fdt32_ld(&prop->len) >= 8)
                return prop->data + 4;
        return prop->data;
}

const void *fdt_getprop_by_offset(const void *fdt, int offset,
                                  const char **namep, int *lenp)
{
        const struct fdt_property *prop;

        prop = fdt_get_property_by_offset_(fdt, offset, lenp);
        if (!prop)
                return NULL;
        if (namep) {
                const char *name;
                int namelen;
                name = fdt_get_string(fdt, fdt32_ld(&prop->nameoff),
                                      &namelen);
                if (!name) {
                        if (lenp)
                                *lenp = namelen;
                        return NULL;
                }
                *namep = name;
        }

        /* Handle realignment */
        if (fdt_version(fdt) < 0x10 && (offset + sizeof(*prop)) % 8 &&
            fdt32_ld(&prop->len) >= 8)
                return prop->data + 4;
        return prop->data;
}

const void *fdt_getprop(const void *fdt, int nodeoffset,
                        const char *name, int *lenp)
{
        return fdt_getprop_namelen(fdt, nodeoffset, name, strlen(name), lenp);
}

uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
{
        const fdt32_t *php;
        int len;

        /* FIXME: This is a bit sub-optimal, since we potentially scan
         * over all the properties twice. */
        php = fdt_getprop(fdt, nodeoffset, "phandle", &len);
        if (!php || (len != sizeof(*php))) {
                php = fdt_getprop(fdt, nodeoffset, "linux,phandle", &len);
                if (!php || (len != sizeof(*php)))
                        return 0;
        }

        return fdt32_ld(php);
}

const char *fdt_get_alias_namelen(const void *fdt,
                                  const char *name, int namelen)
{
        int aliasoffset;

        aliasoffset = fdt_path_offset(fdt, "/aliases");
        if (aliasoffset < 0)
                return NULL;

        return fdt_getprop_namelen(fdt, aliasoffset, name, namelen, NULL);
}

const char *fdt_get_alias(const void *fdt, const char *name)
{
        return fdt_get_alias_namelen(fdt, name, strlen(name));
}

int fdt_get_path(const void *fdt, int nodeoffset, char *buf, int buflen)
{
        int pdepth = 0, p = 0;
        int offset, depth, namelen;
        const char *name;

        FDT_RO_PROBE(fdt);

        if (buflen < 2)
                return -FDT_ERR_NOSPACE;

        for (offset = 0, depth = 0;
             (offset >= 0) && (offset <= nodeoffset);
             offset = fdt_next_node(fdt, offset, &depth)) {
                while (pdepth > depth) {
                        do {
                                p--;
                        } while (buf[p-1] != '/');
                        pdepth--;
                }

                if (pdepth >= depth) {
                        name = fdt_get_name(fdt, offset, &namelen);
                        if (!name)
                                return namelen;
                        if ((p + namelen + 1) <= buflen) {
                                memcpy(buf + p, name, namelen);
                                p += namelen;
                                buf[p++] = '/';
                                pdepth++;
                        }
                }

                if (offset == nodeoffset) {
                        if (pdepth < (depth + 1))
                                return -FDT_ERR_NOSPACE;

                        if (p > 1) /* special case so that root path is "/", not "" */
                                p--;
                        buf[p] = '\0';
                        return 0;
                }
        }

        if ((offset == -FDT_ERR_NOTFOUND) || (offset >= 0))
                return -FDT_ERR_BADOFFSET;
        else if (offset == -FDT_ERR_BADOFFSET)
                return -FDT_ERR_BADSTRUCTURE;

        return offset; /* error from fdt_next_node() */
}

int fdt_supernode_atdepth_offset(const void *fdt, int nodeoffset,
                                 int supernodedepth, int *nodedepth)
{
        int offset, depth;
        int supernodeoffset = -FDT_ERR_INTERNAL;

        FDT_RO_PROBE(fdt);

        if (supernodedepth < 0)
                return -FDT_ERR_NOTFOUND;

        for (offset = 0, depth = 0;
             (offset >= 0) && (offset <= nodeoffset);
             offset = fdt_next_node(fdt, offset, &depth)) {
                if (depth == supernodedepth)
                        supernodeoffset = offset;

                if (offset == nodeoffset) {
                        if (nodedepth)
                                *nodedepth = depth;

                        if (supernodedepth > depth)
                                return -FDT_ERR_NOTFOUND;
                        else
                                return supernodeoffset;
                }
        }

        if ((offset == -FDT_ERR_NOTFOUND) || (offset >= 0))
                return -FDT_ERR_BADOFFSET;
        else if (offset == -FDT_ERR_BADOFFSET)
                return -FDT_ERR_BADSTRUCTURE;

        return offset; /* error from fdt_next_node() */
}

int fdt_node_depth(const void *fdt, int nodeoffset)
{
        int nodedepth;
        int err;

        err = fdt_supernode_atdepth_offset(fdt, nodeoffset, 0, &nodedepth);
        if (err)
                return (err < 0) ? err : -FDT_ERR_INTERNAL;
        return nodedepth;
}

int fdt_parent_offset(const void *fdt, int nodeoffset)
{
        int nodedepth = fdt_node_depth(fdt, nodeoffset);

        if (nodedepth < 0)
                return nodedepth;
        return fdt_supernode_atdepth_offset(fdt, nodeoffset,
                                            nodedepth - 1, NULL);
}

int fdt_node_offset_by_prop_value(const void *fdt, int startoffset,
                                  const char *propname,
                                  const void *propval, int proplen)
{
        int offset;
        const void *val;
        int len;

        FDT_RO_PROBE(fdt);

        /* FIXME: The algorithm here is pretty horrible: we scan each
         * property of a node in fdt_getprop(), then if that didn't
         * find what we want, we scan over them again making our way
         * to the next node.  Still it's the easiest to implement
         * approach; performance can come later. */
        for (offset = fdt_next_node(fdt, startoffset, NULL);
             offset >= 0;
             offset = fdt_next_node(fdt, offset, NULL)) {
                val = fdt_getprop(fdt, offset, propname, &len);
                if (val && (len == proplen)
                    && (memcmp(val, propval, len) == 0))
                        return offset;
        }

        return offset; /* error from fdt_next_node() */
}

int fdt_node_offset_by_phandle(const void *fdt, uint32_t phandle)
{
        int offset;

        if ((phandle == 0) || (phandle == -1))
                return -FDT_ERR_BADPHANDLE;

        FDT_RO_PROBE(fdt);

        /* FIXME: The algorithm here is pretty horrible: we
         * potentially scan each property of a node in
         * fdt_get_phandle(), then if that didn't find what
         * we want, we scan over them again making our way to the next
         * node.  Still it's the easiest to implement approach;
         * performance can come later. */
        for (offset = fdt_next_node(fdt, -1, NULL);
             offset >= 0;
             offset = fdt_next_node(fdt, offset, NULL)) {
                if (fdt_get_phandle(fdt, offset) == phandle)
                        return offset;
        }

        return offset; /* error from fdt_next_node() */
}

int fdt_stringlist_contains(const char *strlist, int listlen, const char *str)
{
        int len = strlen(str);
        const char *p;

        while (listlen >= len) {
                if (memcmp(str, strlist, len+1) == 0)
                        return 1;
                p = memchr(strlist, '\0', listlen);
                if (!p)
                        return 0; /* malformed strlist.. */
                listlen -= (p-strlist) + 1;
                strlist = p + 1;
        }
        return 0;
}

int fdt_stringlist_count(const void *fdt, int nodeoffset, const char *property)
{
        const char *list, *end;
        int length, count = 0;

        list = fdt_getprop(fdt, nodeoffset, property, &length);
        if (!list)
                return length;

        end = list + length;

        while (list < end) {
                length = strnlen(list, end - list) + 1;

                /* Abort if the last string isn't properly NUL-terminated. */
                if (list + length > end)
                        return -FDT_ERR_BADVALUE;

                list += length;
                count++;
        }

        return count;
}

int fdt_stringlist_search(const void *fdt, int nodeoffset, const char *property,
                          const char *string)
{
        int length, len, idx = 0;
        const char *list, *end;

        list = fdt_getprop(fdt, nodeoffset, property, &length);
        if (!list)
                return length;

        len = strlen(string) + 1;
        end = list + length;

        while (list < end) {
                length = strnlen(list, end - list) + 1;

                /* Abort if the last string isn't properly NUL-terminated. */
                if (list + length > end)
                        return -FDT_ERR_BADVALUE;

                if (length == len && memcmp(list, string, length) == 0)
                        return idx;

                list += length;
                idx++;
        }

        return -FDT_ERR_NOTFOUND;
}

const char *fdt_stringlist_get(const void *fdt, int nodeoffset,
                               const char *property, int idx,
                               int *lenp)
{
        const char *list, *end;
        int length;

        list = fdt_getprop(fdt, nodeoffset, property, &length);
        if (!list) {
                if (lenp)
                        *lenp = length;

                return NULL;
        }

        end = list + length;

        while (list < end) {
                length = strnlen(list, end - list) + 1;

                /* Abort if the last string isn't properly NUL-terminated. */
                if (list + length > end) {
                        if (lenp)
                                *lenp = -FDT_ERR_BADVALUE;

                        return NULL;
                }

                if (idx == 0) {
                        if (lenp)
                                *lenp = length - 1;

                        return list;
                }

                list += length;
                idx--;
        }

        if (lenp)
                *lenp = -FDT_ERR_NOTFOUND;

        return NULL;
}

int fdt_node_check_compatible(const void *fdt, int nodeoffset,
                              const char *compatible)
{
        const void *prop;
        int len;

        prop = fdt_getprop(fdt, nodeoffset, "compatible", &len);
        if (!prop)
                return len;

        return !fdt_stringlist_contains(prop, len, compatible);
}

int fdt_node_offset_by_compatible(const void *fdt, int startoffset,
                                  const char *compatible)
{
        int offset, err;

        FDT_RO_PROBE(fdt);

        /* FIXME: The algorithm here is pretty horrible: we scan each
         * property of a node in fdt_node_check_compatible(), then if
         * that didn't find what we want, we scan over them again
         * making our way to the next node.  Still it's the easiest to
         * implement approach; performance can come later. */
        for (offset = fdt_next_node(fdt, startoffset, NULL);
             offset >= 0;
             offset = fdt_next_node(fdt, offset, NULL)) {
                err = fdt_node_check_compatible(fdt, offset, compatible);
                if ((err < 0) && (err != -FDT_ERR_NOTFOUND))
                        return err;
                else if (err == 0)
                        return offset;
        }

        return offset; /* error from fdt_next_node() */
}

int fdt_check_full(const void *fdt, size_t bufsize)
{
        int err;
        int num_memrsv;
        int offset, nextoffset = 0;
        uint32_t tag;
        unsigned depth = 0;
        const void *prop;
        const char *propname;

        if (bufsize < FDT_V1_SIZE)
                return -FDT_ERR_TRUNCATED;
        err = fdt_check_header(fdt);
        if (err != 0)
                return err;
        if (bufsize < fdt_totalsize(fdt))
                return -FDT_ERR_TRUNCATED;

        num_memrsv = fdt_num_mem_rsv(fdt);
        if (num_memrsv < 0)
                return num_memrsv;

        while (1) {
                offset = nextoffset;
                tag = fdt_next_tag(fdt, offset, &nextoffset);

                if (nextoffset < 0)
                        return nextoffset;

                switch (tag) {
                case FDT_NOP:
                        break;

                case FDT_END:
                        if (depth != 0)
                                return -FDT_ERR_BADSTRUCTURE;
                        return 0;

                case FDT_BEGIN_NODE:
                        depth++;
                        if (depth > INT_MAX)
                                return -FDT_ERR_BADSTRUCTURE;
                        break;

                case FDT_END_NODE:
                        if (depth == 0)
                                return -FDT_ERR_BADSTRUCTURE;
                        depth--;
                        break;

                case FDT_PROP:
                        prop = fdt_getprop_by_offset(fdt, offset, &propname,
                                                     &err);
                        if (!prop)
                                return err;
                        break;

                default:
                        return -FDT_ERR_INTERNAL;
                }
        }
}