flattree.c

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/*
 * (C) Copyright David Gibson <[email protected]>, IBM Corporation.  2005.
 *
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 *                                                                   USA
 */

#include "dtc.h"
#include "srcpos.h"

#define FTF_FULLPATH    0x1
#define FTF_VARALIGN    0x2
#define FTF_NAMEPROPS   0x4
#define FTF_BOOTCPUID   0x8
#define FTF_STRTABSIZE  0x10
#define FTF_STRUCTSIZE  0x20
#define FTF_NOPS    0x40

static struct version_info {
    int version;
    int last_comp_version;
    int hdr_size;
    int flags;
} version_table[] = {
    {1, 1, FDT_V1_SIZE,
     FTF_FULLPATH|FTF_VARALIGN|FTF_NAMEPROPS},
    {2, 1, FDT_V2_SIZE,
     FTF_FULLPATH|FTF_VARALIGN|FTF_NAMEPROPS|FTF_BOOTCPUID},
    {3, 1, FDT_V3_SIZE,
     FTF_FULLPATH|FTF_VARALIGN|FTF_NAMEPROPS|FTF_BOOTCPUID|FTF_STRTABSIZE},
    {16, 16, FDT_V3_SIZE,
     FTF_BOOTCPUID|FTF_STRTABSIZE|FTF_NOPS},
    {17, 16, FDT_V17_SIZE,
     FTF_BOOTCPUID|FTF_STRTABSIZE|FTF_STRUCTSIZE|FTF_NOPS},
};

struct emitter {
    void (*cell)(void *, cell_t);
    void (*string)(void *, char *, int);
    void (*align)(void *, int);
    void (*data)(void *, struct data);
    void (*beginnode)(void *, struct label *labels);
    void (*endnode)(void *, struct label *labels);
    void (*property)(void *, struct label *labels);
};

static void bin_emit_cell(void *e, cell_t val)
{
    struct data *dtbuf = e;

    *dtbuf = data_append_cell(*dtbuf, val);
}

static void bin_emit_string(void *e, char *str, int len)
{
    struct data *dtbuf = e;

    if (len == 0)
        len = strlen(str);

    *dtbuf = data_append_data(*dtbuf, str, len);
    *dtbuf = data_append_byte(*dtbuf, '\0');
}

static void bin_emit_align(void *e, int a)
{
    struct data *dtbuf = e;

    *dtbuf = data_append_align(*dtbuf, a);
}

static void bin_emit_data(void *e, struct data d)
{
    struct data *dtbuf = e;

    *dtbuf = data_append_data(*dtbuf, d.val, d.len);
}

static void bin_emit_beginnode(void *e, struct label *labels)
{
    bin_emit_cell(e, FDT_BEGIN_NODE);
}

static void bin_emit_endnode(void *e, struct label *labels)
{
    bin_emit_cell(e, FDT_END_NODE);
}

static void bin_emit_property(void *e, struct label *labels)
{
    bin_emit_cell(e, FDT_PROP);
}

static struct emitter bin_emitter = {
    .cell = bin_emit_cell,
    .string = bin_emit_string,
    .align = bin_emit_align,
    .data = bin_emit_data,
    .beginnode = bin_emit_beginnode,
    .endnode = bin_emit_endnode,
    .property = bin_emit_property,
};

static void emit_label(FILE *f, const char *prefix, const char *label)
{
    fprintf(f, "\t.globl\t%s_%s\n", prefix, label);
    fprintf(f, "%s_%s:\n", prefix, label);
    fprintf(f, "_%s_%s:\n", prefix, label);
}

static void emit_offset_label(FILE *f, const char *label, int offset)
{
    fprintf(f, "\t.globl\t%s\n", label);
    fprintf(f, "%s\t= . + %d\n", label, offset);
}

#define ASM_EMIT_BELONG(f, fmt, ...) \
    { \
        fprintf((f), "\t.byte\t((" fmt ") >> 24) & 0xff\n", __VA_ARGS__); \
        fprintf((f), "\t.byte\t((" fmt ") >> 16) & 0xff\n", __VA_ARGS__); \
        fprintf((f), "\t.byte\t((" fmt ") >> 8) & 0xff\n", __VA_ARGS__); \
        fprintf((f), "\t.byte\t(" fmt ") & 0xff\n", __VA_ARGS__); \
    }

static void asm_emit_cell(void *e, cell_t val)
{
    FILE *f = e;

    fprintf(f, "\t.byte 0x%02x; .byte 0x%02x; .byte 0x%02x; .byte 0x%02x\n",
        (val >> 24) & 0xff, (val >> 16) & 0xff,
        (val >> 8) & 0xff, val & 0xff);
}

static void asm_emit_string(void *e, char *str, int len)
{
    FILE *f = e;
    char c = 0;

    if (len != 0) {
        /* XXX: ewww */
        c = str[len];
        str[len] = '\0';
    }

    fprintf(f, "\t.string\t\"%s\"\n", str);

    if (len != 0) {
        str[len] = c;
    }
}

static void asm_emit_align(void *e, int a)
{
    FILE *f = e;

    fprintf(f, "\t.balign\t%d, 0\n", a);
}

static void asm_emit_data(void *e, struct data d)
{
    FILE *f = e;
    int off = 0;
    struct marker *m = d.markers;

    for_each_marker_of_type(m, LABEL)
        emit_offset_label(f, m->ref, m->offset);

    while ((d.len - off) >= sizeof(uint32_t)) {
        asm_emit_cell(e, fdt32_to_cpu(*((uint32_t *)(d.val+off))));
        off += sizeof(uint32_t);
    }

    while ((d.len - off) >= 1) {
        fprintf(f, "\t.byte\t0x%hhx\n", d.val[off]);
        off += 1;
    }

    assert(off == d.len);
}

static void asm_emit_beginnode(void *e, struct label *labels)
{
    FILE *f = e;
    struct label *l;

    for_each_label(labels, l) {
        fprintf(f, "\t.globl\t%s\n", l->label);
        fprintf(f, "%s:\n", l->label);
    }
    fprintf(f, "\t/* FDT_BEGIN_NODE */\n");
    asm_emit_cell(e, FDT_BEGIN_NODE);
}

static void asm_emit_endnode(void *e, struct label *labels)
{
    FILE *f = e;
    struct label *l;

    fprintf(f, "\t/* FDT_END_NODE */\n");
    asm_emit_cell(e, FDT_END_NODE);
    for_each_label(labels, l) {
        fprintf(f, "\t.globl\t%s_end\n", l->label);
        fprintf(f, "%s_end:\n", l->label);
    }
}

static void asm_emit_property(void *e, struct label *labels)
{
    FILE *f = e;
    struct label *l;

    for_each_label(labels, l) {
        fprintf(f, "\t.globl\t%s\n", l->label);
        fprintf(f, "%s:\n", l->label);
    }
    fprintf(f, "\t/* FDT_PROP */\n");
    asm_emit_cell(e, FDT_PROP);
}

static struct emitter asm_emitter = {
    .cell = asm_emit_cell,
    .string = asm_emit_string,
    .align = asm_emit_align,
    .data = asm_emit_data,
    .beginnode = asm_emit_beginnode,
    .endnode = asm_emit_endnode,
    .property = asm_emit_property,
};

static int stringtable_insert(struct data *d, const char *str)
{
    int i;

    /* FIXME: do this more efficiently? */

    for (i = 0; i < d->len; i++) {
        if (streq(str, d->val + i))
            return i;
    }

    *d = data_append_data(*d, str, strlen(str)+1);
    return i;
}

static void flatten_tree(struct node *tree, struct emitter *emit,
             void *etarget, struct data *strbuf,
             struct version_info *vi)
{
    struct property *prop;
    struct node *child;
    int seen_name_prop = 0;

    if (tree->deleted)
        return;

    emit->beginnode(etarget, tree->labels);

    if (vi->flags & FTF_FULLPATH)
        emit->string(etarget, tree->fullpath, 0);
    else
        emit->string(etarget, tree->name, 0);

    emit->align(etarget, sizeof(cell_t));

    for_each_property(tree, prop) {
        int nameoff;

        if (streq(prop->name, "name"))
            seen_name_prop = 1;

        nameoff = stringtable_insert(strbuf, prop->name);

        emit->property(etarget, prop->labels);
        emit->cell(etarget, prop->val.len);
        emit->cell(etarget, nameoff);

        if ((vi->flags & FTF_VARALIGN) && (prop->val.len >= 8))
            emit->align(etarget, 8);

        emit->data(etarget, prop->val);
        emit->align(etarget, sizeof(cell_t));
    }

    if ((vi->flags & FTF_NAMEPROPS) && !seen_name_prop) {
        emit->property(etarget, NULL);
        emit->cell(etarget, tree->basenamelen+1);
        emit->cell(etarget, stringtable_insert(strbuf, "name"));

        if ((vi->flags & FTF_VARALIGN) && ((tree->basenamelen+1) >= 8))
            emit->align(etarget, 8);

        emit->string(etarget, tree->name, tree->basenamelen);
        emit->align(etarget, sizeof(cell_t));
    }

    for_each_child(tree, child) {
        flatten_tree(child, emit, etarget, strbuf, vi);
    }

    emit->endnode(etarget, tree->labels);
}

static struct data flatten_reserve_list(struct reserve_info *reservelist,
                 struct version_info *vi)
{
    struct reserve_info *re;
    struct data d = empty_data;
    static struct fdt_reserve_entry null_re = {0,0};
    int    j;

    for (re = reservelist; re; re = re->next) {
        d = data_append_re(d, &re->re);
    }
    /*
     * Add additional reserved slots if the user asked for them.
     */
    for (j = 0; j < reservenum; j++) {
        d = data_append_re(d, &null_re);
    }

    return d;
}

static void make_fdt_header(struct fdt_header *fdt,
                struct version_info *vi,
                int reservesize, int dtsize, int strsize,
                int boot_cpuid_phys)
{
    int reserve_off;

    reservesize += sizeof(struct fdt_reserve_entry);

    memset(fdt, 0xff, sizeof(*fdt));

    fdt->magic = cpu_to_fdt32(FDT_MAGIC);
    fdt->version = cpu_to_fdt32(vi->version);
    fdt->last_comp_version = cpu_to_fdt32(vi->last_comp_version);

    /* Reserve map should be doubleword aligned */
    reserve_off = ALIGN(vi->hdr_size, 8);

    fdt->off_mem_rsvmap = cpu_to_fdt32(reserve_off);
    fdt->off_dt_struct = cpu_to_fdt32(reserve_off + reservesize);
    fdt->off_dt_strings = cpu_to_fdt32(reserve_off + reservesize
                      + dtsize);
    fdt->totalsize = cpu_to_fdt32(reserve_off + reservesize + dtsize + strsize);

    if (vi->flags & FTF_BOOTCPUID)
        fdt->boot_cpuid_phys = cpu_to_fdt32(boot_cpuid_phys);
    if (vi->flags & FTF_STRTABSIZE)
        fdt->size_dt_strings = cpu_to_fdt32(strsize);
    if (vi->flags & FTF_STRUCTSIZE)
        fdt->size_dt_struct = cpu_to_fdt32(dtsize);
}

void dt_to_blob(FILE *f, struct boot_info *bi, int version)
{
    struct version_info *vi = NULL;
    int i;
    struct data blob       = empty_data;
    struct data reservebuf = empty_data;
    struct data dtbuf      = empty_data;
    struct data strbuf     = empty_data;
    struct fdt_header fdt;
    int padlen = 0;

    for (i = 0; i < ARRAY_SIZE(version_table); i++) {
        if (version_table[i].version == version)
            vi = &version_table[i];
    }
    if (!vi)
        die("Unknown device tree blob version %d\n", version);

    flatten_tree(bi->dt, &bin_emitter, &dtbuf, &strbuf, vi);
    bin_emit_cell(&dtbuf, FDT_END);

    reservebuf = flatten_reserve_list(bi->reservelist, vi);

    /* Make header */
    make_fdt_header(&fdt, vi, reservebuf.len, dtbuf.len, strbuf.len,
            bi->boot_cpuid_phys);

    /*
     * If the user asked for more space than is used, adjust the totalsize.
     */
    if (minsize > 0) {
        padlen = minsize - fdt32_to_cpu(fdt.totalsize);
        if ((padlen < 0) && (quiet < 1))
            fprintf(stderr,
                "Warning: blob size %d >= minimum size %d\n",
                fdt32_to_cpu(fdt.totalsize), minsize);
    }

    if (padsize > 0)
        padlen = padsize;

    if (padlen > 0) {
        int tsize = fdt32_to_cpu(fdt.totalsize);
        tsize += padlen;
        fdt.totalsize = cpu_to_fdt32(tsize);
    }

    /*
     * Assemble the blob: start with the header, add with alignment
     * the reserve buffer, add the reserve map terminating zeroes,
     * the device tree itself, and finally the strings.
     */
    blob = data_append_data(blob, &fdt, vi->hdr_size);
    blob = data_append_align(blob, 8);
    blob = data_merge(blob, reservebuf);
    blob = data_append_zeroes(blob, sizeof(struct fdt_reserve_entry));
    blob = data_merge(blob, dtbuf);
    blob = data_merge(blob, strbuf);

    /*
     * If the user asked for more space than is used, pad out the blob.
     */
    if (padlen > 0)
        blob = data_append_zeroes(blob, padlen);

    if (fwrite(blob.val, blob.len, 1, f) != 1) {
        if (ferror(f))
            die("Error writing device tree blob: %s\n",
                strerror(errno));
        else
            die("Short write on device tree blob\n");
    }

    /*
     * data_merge() frees the right-hand element so only the blob
     * remains to be freed.
     */
    data_free(blob);
}

static void dump_stringtable_asm(FILE *f, struct data strbuf)
{
    const char *p;
    int len;

    p = strbuf.val;

    while (p < (strbuf.val + strbuf.len)) {
        len = strlen(p);
        fprintf(f, "\t.string \"%s\"\n", p);
        p += len+1;
    }
}

void dt_to_asm(FILE *f, struct boot_info *bi, int version)
{
    struct version_info *vi = NULL;
    int i;
    struct data strbuf = empty_data;
    struct reserve_info *re;
    const char *symprefix = "dt";

    for (i = 0; i < ARRAY_SIZE(version_table); i++) {
        if (version_table[i].version == version)
            vi = &version_table[i];
    }
    if (!vi)
        die("Unknown device tree blob version %d\n", version);

    fprintf(f, "/* autogenerated by dtc, do not edit */\n\n");

    emit_label(f, symprefix, "blob_start");
    emit_label(f, symprefix, "header");
    fprintf(f, "\t/* magic */\n");
    asm_emit_cell(f, FDT_MAGIC);
    fprintf(f, "\t/* totalsize */\n");
    ASM_EMIT_BELONG(f, "_%s_blob_abs_end - _%s_blob_start",
            symprefix, symprefix);
    fprintf(f, "\t/* off_dt_struct */\n");
    ASM_EMIT_BELONG(f, "_%s_struct_start - _%s_blob_start",
        symprefix, symprefix);
    fprintf(f, "\t/* off_dt_strings */\n");
    ASM_EMIT_BELONG(f, "_%s_strings_start - _%s_blob_start",
        symprefix, symprefix);
    fprintf(f, "\t/* off_mem_rsvmap */\n");
    ASM_EMIT_BELONG(f, "_%s_reserve_map - _%s_blob_start",
        symprefix, symprefix);
    fprintf(f, "\t/* version */\n");
    asm_emit_cell(f, vi->version);
    fprintf(f, "\t/* last_comp_version */\n");
    asm_emit_cell(f, vi->last_comp_version);

    if (vi->flags & FTF_BOOTCPUID) {
        fprintf(f, "\t/* boot_cpuid_phys */\n");
        asm_emit_cell(f, bi->boot_cpuid_phys);
    }

    if (vi->flags & FTF_STRTABSIZE) {
        fprintf(f, "\t/* size_dt_strings */\n");
        ASM_EMIT_BELONG(f, "_%s_strings_end - _%s_strings_start",
                symprefix, symprefix);
    }

    if (vi->flags & FTF_STRUCTSIZE) {
        fprintf(f, "\t/* size_dt_struct */\n");
        ASM_EMIT_BELONG(f, "_%s_struct_end - _%s_struct_start",
            symprefix, symprefix);
    }

    /*
     * Reserve map entries.
     * Align the reserve map to a doubleword boundary.
     * Each entry is an (address, size) pair of u64 values.
     * Always supply a zero-sized temination entry.
     */
    asm_emit_align(f, 8);
    emit_label(f, symprefix, "reserve_map");

    fprintf(f, "/* Memory reserve map from source file */\n");

    /*
     * Use .long on high and low halfs of u64s to avoid .quad
     * as it appears .quad isn't available in some assemblers.
     */
    for (re = bi->reservelist; re; re = re->next) {
        struct label *l;

        for_each_label(re->labels, l) {
            fprintf(f, "\t.globl\t%s\n", l->label);
            fprintf(f, "%s:\n", l->label);
        }
        ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->re.address >> 32));
        ASM_EMIT_BELONG(f, "0x%08x",
                (unsigned int)(re->re.address & 0xffffffff));
        ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->re.size >> 32));
        ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->re.size & 0xffffffff));
    }
    for (i = 0; i < reservenum; i++) {
        fprintf(f, "\t.long\t0, 0\n\t.long\t0, 0\n");
    }

    fprintf(f, "\t.long\t0, 0\n\t.long\t0, 0\n");

    emit_label(f, symprefix, "struct_start");
    flatten_tree(bi->dt, &asm_emitter, f, &strbuf, vi);

    fprintf(f, "\t/* FDT_END */\n");
    asm_emit_cell(f, FDT_END);
    emit_label(f, symprefix, "struct_end");

    emit_label(f, symprefix, "strings_start");
    dump_stringtable_asm(f, strbuf);
    emit_label(f, symprefix, "strings_end");

    emit_label(f, symprefix, "blob_end");

    /*
     * If the user asked for more space than is used, pad it out.
     */
    if (minsize > 0) {
        fprintf(f, "\t.space\t%d - (_%s_blob_end - _%s_blob_start), 0\n",
            minsize, symprefix, symprefix);
    }
    if (padsize > 0) {
        fprintf(f, "\t.space\t%d, 0\n", padsize);
    }
    emit_label(f, symprefix, "blob_abs_end");

    data_free(strbuf);
}

struct inbuf {
    char *base, *limit, *ptr;
};

static void inbuf_init(struct inbuf *inb, void *base, void *limit)
{
    inb->base = base;
    inb->limit = limit;
    inb->ptr = inb->base;
}

static void flat_read_chunk(struct inbuf *inb, void *p, int len)
{
    if ((inb->ptr + len) > inb->limit)
        die("Premature end of data parsing flat device tree\n");

    memcpy(p, inb->ptr, len);

    inb->ptr += len;
}

static uint32_t flat_read_word(struct inbuf *inb)
{
    uint32_t val;

    assert(((inb->ptr - inb->base) % sizeof(val)) == 0);

    flat_read_chunk(inb, &val, sizeof(val));

    return fdt32_to_cpu(val);
}

static void flat_realign(struct inbuf *inb, int align)
{
    int off = inb->ptr - inb->base;

    inb->ptr = inb->base + ALIGN(off, align);
    if (inb->ptr > inb->limit)
        die("Premature end of data parsing flat device tree\n");
}

static char *flat_read_string(struct inbuf *inb)
{
    int len = 0;
    const char *p = inb->ptr;
    char *str;

    do {
        if (p >= inb->limit)
            die("Premature end of data parsing flat device tree\n");
        len++;
    } while ((*p++) != '\0');

    str = xstrdup(inb->ptr);

    inb->ptr += len;

    flat_realign(inb, sizeof(uint32_t));

    return str;
}

static struct data flat_read_data(struct inbuf *inb, int len)
{
    struct data d = empty_data;

    if (len == 0)
        return empty_data;

    d = data_grow_for(d, len);
    d.len = len;

    flat_read_chunk(inb, d.val, len);

    flat_realign(inb, sizeof(uint32_t));

    return d;
}

static char *flat_read_stringtable(struct inbuf *inb, int offset)
{
    const char *p;

    p = inb->base + offset;
    while (1) {
        if (p >= inb->limit || p < inb->base)
            die("String offset %d overruns string table\n",
                offset);

        if (*p == '\0')
            break;

        p++;
    }

    return xstrdup(inb->base + offset);
}

static struct property *flat_read_property(struct inbuf *dtbuf,
                       struct inbuf *strbuf, int flags)
{
    uint32_t proplen, stroff;
    char *name;
    struct data val;

    proplen = flat_read_word(dtbuf);
    stroff = flat_read_word(dtbuf);

    name = flat_read_stringtable(strbuf, stroff);

    if ((flags & FTF_VARALIGN) && (proplen >= 8))
        flat_realign(dtbuf, 8);

    val = flat_read_data(dtbuf, proplen);

    return build_property(name, val);
}


static struct reserve_info *flat_read_mem_reserve(struct inbuf *inb)
{
    struct reserve_info *reservelist = NULL;
    struct reserve_info *new;
    struct fdt_reserve_entry re;

    /*
     * Each entry is a pair of u64 (addr, size) values for 4 cell_t's.
     * List terminates at an entry with size equal to zero.
     *
     * First pass, count entries.
     */
    while (1) {
        flat_read_chunk(inb, &re, sizeof(re));
        re.address  = fdt64_to_cpu(re.address);
        re.size = fdt64_to_cpu(re.size);
        if (re.size == 0)
            break;

        new = build_reserve_entry(re.address, re.size);
        reservelist = add_reserve_entry(reservelist, new);
    }

    return reservelist;
}


static char *nodename_from_path(const char *ppath, const char *cpath)
{
    int plen;

    plen = strlen(ppath);

    if (!strneq(ppath, cpath, plen))
        die("Path \"%s\" is not valid as a child of \"%s\"\n",
            cpath, ppath);

    /* root node is a special case */
    if (!streq(ppath, "/"))
        plen++;

    return xstrdup(cpath + plen);
}

static struct node *unflatten_tree(struct inbuf *dtbuf,
                   struct inbuf *strbuf,
                   const char *parent_flatname, int flags)
{
    struct node *node;
    char *flatname;
    uint32_t val;

    node = build_node(NULL, NULL);

    flatname = flat_read_string(dtbuf);

    if (flags & FTF_FULLPATH)
        node->name = nodename_from_path(parent_flatname, flatname);
    else
        node->name = flatname;

    do {
        struct property *prop;
        struct node *child;

        val = flat_read_word(dtbuf);
        switch (val) {
        case FDT_PROP:
            if (node->children)
                fprintf(stderr, "Warning: Flat tree input has "
                    "subnodes preceding a property.\n");
            prop = flat_read_property(dtbuf, strbuf, flags);
            add_property(node, prop);
            break;

        case FDT_BEGIN_NODE:
            child = unflatten_tree(dtbuf,strbuf, flatname, flags);
            add_child(node, child);
            break;

        case FDT_END_NODE:
            break;

        case FDT_END:
            die("Premature FDT_END in device tree blob\n");
            break;

        case FDT_NOP:
            if (!(flags & FTF_NOPS))
                fprintf(stderr, "Warning: NOP tag found in flat tree"
                    " version <16\n");

            /* Ignore */
            break;

        default:
            die("Invalid opcode word %08x in device tree blob\n",
                val);
        }
    } while (val != FDT_END_NODE);

    return node;
}


struct boot_info *dt_from_blob(const char *fname)
{
    FILE *f;
    uint32_t magic, totalsize, version, size_dt, boot_cpuid_phys;
    uint32_t off_dt, off_str, off_mem_rsvmap;
    int rc;
    char *blob;
    struct fdt_header *fdt;
    char *p;
    struct inbuf dtbuf, strbuf;
    struct inbuf memresvbuf;
    int sizeleft;
    struct reserve_info *reservelist;
    struct node *tree;
    uint32_t val;
    int flags = 0;

    f = srcfile_relative_open(fname, NULL);

    rc = fread(&magic, sizeof(magic), 1, f);
    if (ferror(f))
        die("Error reading DT blob magic number: %s\n",
            strerror(errno));
    if (rc < 1) {
        if (feof(f))
            die("EOF reading DT blob magic number\n");
        else
            die("Mysterious short read reading magic number\n");
    }

    magic = fdt32_to_cpu(magic);
    if (magic != FDT_MAGIC)
        die("Blob has incorrect magic number\n");

    rc = fread(&totalsize, sizeof(totalsize), 1, f);
    if (ferror(f))
        die("Error reading DT blob size: %s\n", strerror(errno));
    if (rc < 1) {
        if (feof(f))
            die("EOF reading DT blob size\n");
        else
            die("Mysterious short read reading blob size\n");
    }

    totalsize = fdt32_to_cpu(totalsize);
    if (totalsize < FDT_V1_SIZE)
        die("DT blob size (%d) is too small\n", totalsize);

    blob = xmalloc(totalsize);

    fdt = (struct fdt_header *)blob;
    fdt->magic = cpu_to_fdt32(magic);
    fdt->totalsize = cpu_to_fdt32(totalsize);

    sizeleft = totalsize - sizeof(magic) - sizeof(totalsize);
    p = blob + sizeof(magic)  + sizeof(totalsize);

    while (sizeleft) {
        if (feof(f))
            die("EOF before reading %d bytes of DT blob\n",
                totalsize);

        rc = fread(p, 1, sizeleft, f);
        if (ferror(f))
            die("Error reading DT blob: %s\n",
                strerror(errno));

        sizeleft -= rc;
        p += rc;
    }

    off_dt = fdt32_to_cpu(fdt->off_dt_struct);
    off_str = fdt32_to_cpu(fdt->off_dt_strings);
    off_mem_rsvmap = fdt32_to_cpu(fdt->off_mem_rsvmap);
    version = fdt32_to_cpu(fdt->version);
    boot_cpuid_phys = fdt32_to_cpu(fdt->boot_cpuid_phys);

    if (off_mem_rsvmap >= totalsize)
        die("Mem Reserve structure offset exceeds total size\n");

    if (off_dt >= totalsize)
        die("DT structure offset exceeds total size\n");

    if (off_str > totalsize)
        die("String table offset exceeds total size\n");

    if (version >= 3) {
        uint32_t size_str = fdt32_to_cpu(fdt->size_dt_strings);
        if (off_str+size_str > totalsize)
            die("String table extends past total size\n");
        inbuf_init(&strbuf, blob + off_str, blob + off_str + size_str);
    } else {
        inbuf_init(&strbuf, blob + off_str, blob + totalsize);
    }

    if (version >= 17) {
        size_dt = fdt32_to_cpu(fdt->size_dt_struct);
        if (off_dt+size_dt > totalsize)
            die("Structure block extends past total size\n");
    }

    if (version < 16) {
        flags |= FTF_FULLPATH | FTF_NAMEPROPS | FTF_VARALIGN;
    } else {
        flags |= FTF_NOPS;
    }

    inbuf_init(&memresvbuf,
           blob + off_mem_rsvmap, blob + totalsize);
    inbuf_init(&dtbuf, blob + off_dt, blob + totalsize);

    reservelist = flat_read_mem_reserve(&memresvbuf);

    val = flat_read_word(&dtbuf);

    if (val != FDT_BEGIN_NODE)
        die("Device tree blob doesn't begin with FDT_BEGIN_NODE (begins with 0x%08x)\n", val);

    tree = unflatten_tree(&dtbuf, &strbuf, "", flags);

    val = flat_read_word(&dtbuf);
    if (val != FDT_END)
        die("Device tree blob doesn't end with FDT_END\n");

    free(blob);

    fclose(f);

    return build_boot_info(reservelist, tree, boot_cpuid_phys);
}