// SPDX-License-Identifier: GPL-2.0-or-later

/*

 * (C) Copyright David Gibson <dwg@au1.ibm.com>, IBM Corporation.  2005.

 */

#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 *, const 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, const 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, const char *str, int len)

{

	FILE *f = e;

	if (len != 0)

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

	else

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

}

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(*((fdt32_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;

	bool seen_name_prop = false;

	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 = true;

		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;

	int    j;

	for (re = reservelist; re; re = re->next) {

		d = data_append_re(d, re->address, re->size);

	}

	/*

	 * Add additional reserved slots if the user asked for them.

	 */

	for (j = 0; j < reservenum; j++) {

		d = data_append_re(d, 0, 0);

	}

	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 dt_info *dti, 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(dti->dt, &bin_emitter, &dtbuf, &strbuf, vi);

	bin_emit_cell(&dtbuf, FDT_END);

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

	/* Make header */

	make_fdt_header(&fdt, vi, reservebuf.len, dtbuf.len, strbuf.len,

			dti->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) {

			padlen = 0;

			if (quiet < 1)

				fprintf(stderr,

					"Warning: blob size %"PRIu32" >= minimum size %d\n",

					fdt32_to_cpu(fdt.totalsize), minsize);

		}

	}

	if (padsize > 0)

		padlen = padsize;

	if (alignsize > 0)

		padlen = ALIGN(fdt32_to_cpu(fdt.totalsize) + padlen, alignsize)

			- fdt32_to_cpu(fdt.totalsize);

	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 dt_info *dti, 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, dti->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 halves of u64s to avoid .quad

	 * as it appears .quad isn't available in some assemblers.

	 */

	for (re = dti->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->address >> 32));

		ASM_EMIT_BELONG(f, "0x%08x",

				(unsigned int)(re->address & 0xffffffff));

		ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->size >> 32));

		ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(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(dti->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);

	}

	if (alignsize > 0)

		asm_emit_align(f, alignsize);

	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)

{

	fdt32_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, NULL);

}

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) {

		uint64_t address, size;

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

		address  = fdt64_to_cpu(re.address);

		size = fdt64_to_cpu(re.size);

		if (size == 0)

			break;

		new = build_reserve_entry(address, 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 (!strstarts(cpath, ppath))

		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, 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);

	if (node->name != flatname) {

		free(flatname);

	}

	return node;

}

struct dt_info *dt_from_blob(const char *fname)

{

	FILE *f;

	fdt32_t magic_buf, totalsize_buf;

	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_buf, sizeof(magic_buf), 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_buf);

	if (magic != FDT_MAGIC)

		die("Blob has incorrect magic number\n");

	rc = fread(&totalsize_buf, sizeof(totalsize_buf), 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_buf);

	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");