source: rtems/cpukit/dtc/libfdt/fdt.c @ 8073f95e

/*
 * 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"

/*
 * Minimal sanity check for a read-only tree. fdt_ro_probe_() checks
 * that the given buffer contains what appears to be a flattened
 * device tree with sane information in its header.
 */
int fdt_ro_probe_(const void *fdt)
{
        if (fdt_magic(fdt) == FDT_MAGIC) {
                /* Complete tree */
                if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
                        return -FDT_ERR_BADVERSION;
                if (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION)
                        return -FDT_ERR_BADVERSION;
        } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
                /* Unfinished sequential-write blob */
                if (fdt_size_dt_struct(fdt) == 0)
                        return -FDT_ERR_BADSTATE;
        } else {
                return -FDT_ERR_BADMAGIC;
        }

        return 0;
}

static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
{
        return (off >= hdrsize) && (off <= totalsize);
}

static int check_block_(uint32_t hdrsize, uint32_t totalsize,
                        uint32_t base, uint32_t size)
{
        if (!check_off_(hdrsize, totalsize, base))
                return 0; /* block start out of bounds */
        if ((base + size) < base)
                return 0; /* overflow */
        if (!check_off_(hdrsize, totalsize, base + size))
                return 0; /* block end out of bounds */
        return 1;
}

int fdt_check_header(const void *fdt)
{
        size_t hdrsize = FDT_V16_SIZE;

        if (fdt_magic(fdt) != FDT_MAGIC)
                return -FDT_ERR_BADMAGIC;
        if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
            || (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION))
                return -FDT_ERR_BADVERSION;
        if (fdt_version(fdt) < fdt_last_comp_version(fdt))
                return -FDT_ERR_BADVERSION;

        if (fdt_version(fdt) >= 17)
                hdrsize = FDT_V17_SIZE;

        if ((fdt_totalsize(fdt) < hdrsize)
            || (fdt_totalsize(fdt) > INT_MAX))
                return -FDT_ERR_TRUNCATED;

        /* Bounds check memrsv block */
        if (!check_off_(hdrsize, fdt_totalsize(fdt), fdt_off_mem_rsvmap(fdt)))
                return -FDT_ERR_TRUNCATED;

        /* Bounds check structure block */
        if (fdt_version(fdt) < 17) {
                if (!check_off_(hdrsize, fdt_totalsize(fdt),
                                fdt_off_dt_struct(fdt)))
                        return -FDT_ERR_TRUNCATED;
        } else {
                if (!check_block_(hdrsize, fdt_totalsize(fdt),
                                  fdt_off_dt_struct(fdt),
                                  fdt_size_dt_struct(fdt)))
                        return -FDT_ERR_TRUNCATED;
        }

        /* Bounds check strings block */
        if (!check_block_(hdrsize, fdt_totalsize(fdt),
                          fdt_off_dt_strings(fdt), fdt_size_dt_strings(fdt)))
                return -FDT_ERR_TRUNCATED;

        return 0;
}

const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
{
        unsigned absoffset = offset + fdt_off_dt_struct(fdt);

        if ((absoffset < offset)
            || ((absoffset + len) < absoffset)
            || (absoffset + len) > fdt_totalsize(fdt))
                return NULL;

        if (fdt_version(fdt) >= 0x11)
                if (((offset + len) < offset)
                    || ((offset + len) > fdt_size_dt_struct(fdt)))
                        return NULL;

        return fdt_offset_ptr_(fdt, offset);
}

uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
{
        const fdt32_t *tagp, *lenp;
        uint32_t tag;
        int offset = startoffset;
        const char *p;

        *nextoffset = -FDT_ERR_TRUNCATED;
        tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
        if (!tagp)
                return FDT_END; /* premature end */
        tag = fdt32_to_cpu(*tagp);
        offset += FDT_TAGSIZE;

        *nextoffset = -FDT_ERR_BADSTRUCTURE;
        switch (tag) {
        case FDT_BEGIN_NODE:
                /* skip name */
                do {
                        p = fdt_offset_ptr(fdt, offset++, 1);
                } while (p && (*p != '\0'));
                if (!p)
                        return FDT_END; /* premature end */
                break;

        case FDT_PROP:
                lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
                if (!lenp)
                        return FDT_END; /* premature end */
                /* skip-name offset, length and value */
                offset += sizeof(struct fdt_property) - FDT_TAGSIZE
                        + fdt32_to_cpu(*lenp);
                if (fdt_version(fdt) < 0x10 && fdt32_to_cpu(*lenp) >= 8 &&
                    ((offset - fdt32_to_cpu(*lenp)) % 8) != 0)
                        offset += 4;
                break;

        case FDT_END:
        case FDT_END_NODE:
        case FDT_NOP:
                break;

        default:
                return FDT_END;
        }

        if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
                return FDT_END; /* premature end */

        *nextoffset = FDT_TAGALIGN(offset);
        return tag;
}

int fdt_check_node_offset_(const void *fdt, int offset)
{
        if ((offset < 0) || (offset % FDT_TAGSIZE)
            || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
                return -FDT_ERR_BADOFFSET;

        return offset;
}

int fdt_check_prop_offset_(const void *fdt, int offset)
{
        if ((offset < 0) || (offset % FDT_TAGSIZE)
            || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
                return -FDT_ERR_BADOFFSET;

        return offset;
}

int fdt_next_node(const void *fdt, int offset, int *depth)
{
        int nextoffset = 0;
        uint32_t tag;

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

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

                switch (tag) {
                case FDT_PROP:
                case FDT_NOP:
                        break;

                case FDT_BEGIN_NODE:
                        if (depth)
                                (*depth)++;
                        break;

                case FDT_END_NODE:
                        if (depth && ((--(*depth)) < 0))
                                return nextoffset;
                        break;

                case FDT_END:
                        if ((nextoffset >= 0)
                            || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
                                return -FDT_ERR_NOTFOUND;
                        else
                                return nextoffset;
                }
        } while (tag != FDT_BEGIN_NODE);

        return offset;
}

int fdt_first_subnode(const void *fdt, int offset)
{
        int depth = 0;

        offset = fdt_next_node(fdt, offset, &depth);
        if (offset < 0 || depth != 1)
                return -FDT_ERR_NOTFOUND;

        return offset;
}

int fdt_next_subnode(const void *fdt, int offset)
{
        int depth = 1;

        /*
         * With respect to the parent, the depth of the next subnode will be
         * the same as the last.
         */
        do {
                offset = fdt_next_node(fdt, offset, &depth);
                if (offset < 0 || depth < 1)
                        return -FDT_ERR_NOTFOUND;
        } while (depth > 1);

        return offset;
}

const char *fdt_find_string_(const char *strtab, int tabsize, const char *s)
{
        int len = strlen(s) + 1;
        const char *last = strtab + tabsize - len;
        const char *p;

        for (p = strtab; p <= last; p++)
                if (memcmp(p, s, len) == 0)
                        return p;
        return NULL;
}

int fdt_move(const void *fdt, void *buf, int bufsize)
{
        FDT_RO_PROBE(fdt);

        if (fdt_totalsize(fdt) > bufsize)
                return -FDT_ERR_NOSPACE;

        memmove(buf, fdt, fdt_totalsize(fdt));
        return 0;
}