Assemble the blob in memory before writing it out.

This makes padding out the blob if the user requested extra size much
easer.  The assembly and writing to the file is more straight forward too.

Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

flattree.c

@@ -307,9 +307,10 @@ static struct data flatten_reserve_list(struct reserve_info *reservelist,
 	for (j = 0; j < reservenum; j++) {
 		d = data_append_re(d, &null_re);
 	}
-	
+
 	return d;
 }
+
 static void make_bph(struct boot_param_header *bph,
 		     struct version_info *vi,
 		     int reservesize, int dtsize, int strsize,
@@ -332,19 +333,8 @@ static void make_bph(struct boot_param_header *bph,
 	bph->off_dt_struct = cpu_to_be32(reserve_off + reservesize);
 	bph->off_dt_strings = cpu_to_be32(reserve_off + reservesize
 					  + dtsize);
-	bph->totalsize = reserve_off + reservesize + dtsize + strsize;
-	if (minsize > 0) {
-		if (bph->totalsize >= minsize) {
-			if (quiet < 1)
-				fprintf(stderr,
-					"Warning: blob size %d >= minimum size %d\n",
-					bph->totalsize, minsize);
+	bph->totalsize = cpu_to_be32(reserve_off + reservesize + dtsize + strsize);
 
-		} else
-			bph->totalsize = minsize;
-	}
-	bph->totalsize = cpu_to_be32(bph->totalsize);
-		
 	if (vi->flags & FTF_BOOTCPUID)
 		bph->boot_cpuid_phys = cpu_to_be32(boot_cpuid_phys);
 	if (vi->flags & FTF_STRTABSIZE)
@@ -358,11 +348,11 @@ void dt_to_blob(FILE *f, struct boot_info *bi, int version,
 {
 	struct version_info *vi = NULL;
 	int i;
-	struct data dtbuf = empty_data;
-	struct data strbuf = empty_data;
-	struct data reservebuf;
+	struct data blob       = empty_data;
+	struct data reservebuf = empty_data;
+	struct data dtbuf      = empty_data;
+	struct data strbuf     = empty_data;
 	struct boot_param_header bph;
-	struct reserve_entry termre = {.address = 0, .size = 0};
 
 	for (i = 0; i < ARRAY_SIZE(version_table); i++) {
 		if (version_table[i].version == version)
@@ -371,9 +361,6 @@ void dt_to_blob(FILE *f, struct boot_info *bi, int version,
 	if (!vi)
 		die("Unknown device tree blob version %d\n", version);
 
-	dtbuf = empty_data;
-	strbuf = empty_data;
-
 	flatten_tree(bi->dt, &bin_emitter, &dtbuf, &strbuf, vi);
 	bin_emit_cell(&dtbuf, OF_DT_END);
 
@@ -383,28 +370,45 @@ void dt_to_blob(FILE *f, struct boot_info *bi, int version,
 	make_bph(&bph, vi, reservebuf.len, dtbuf.len, strbuf.len,
 		 boot_cpuid_phys);
 
-	fwrite(&bph, vi->hdr_size, 1, f);
-
-	/* Align the reserve map to an 8 byte boundary */
-	for (i = vi->hdr_size; i < be32_to_cpu(bph.off_mem_rsvmap); i++)
-		fputc(0, f);
+	/*
+	 * 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, &bph, sizeof(bph));
+	blob = data_append_align(blob, 8);
+	blob = data_merge(blob, reservebuf);
+	blob = data_append_zeroes(blob, sizeof(struct reserve_entry));
+	blob = data_merge(blob, dtbuf);
+	blob = data_merge(blob, strbuf);
 
 	/*
-	 * Reserve map entries.
-	 * Each entry is an (address, size) pair of u64 values.
-	 * Always supply a zero-sized temination entry.
+	 * If the user asked for more space than is used, pad out the blob.
 	 */
-	fwrite(reservebuf.val, reservebuf.len, 1, f);
-	fwrite(&termre, sizeof(termre), 1, f);
+	if (minsize > 0) {
+		int padlen = minsize - be32_to_cpu(bph.totalsize);
+
+		if (padlen > 0) {
+			blob = data_append_zeroes(blob, padlen);
+			bph.totalsize = cpu_to_be32(minsize);
+		} else {
+			if (quiet < 1)
+				fprintf(stderr,
+					"Warning: blob size %d >= minimum size %d\n",
+					be32_to_cpu(bph.totalsize), minsize);
+		}
+	}
 
-	fwrite(dtbuf.val, dtbuf.len, 1, f);
-	fwrite(strbuf.val, strbuf.len, 1, f);
+	fwrite(blob.val, blob.len, 1, f);
 
 	if (ferror(f))
 		die("Error writing device tree blob: %s\n", strerror(errno));
 
-	data_free(dtbuf);
-	data_free(strbuf);
+	/*
+	 * 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)
@@ -447,7 +451,7 @@ void dt_to_asm(FILE *f, struct boot_info *bi, int version, int boot_cpuid_phys)
 	emit_label(f, symprefix, "blob_start");
 	emit_label(f, symprefix, "header");
 	fprintf(f, "\t.long\tOF_DT_HEADER /* magic */\n");
-	fprintf(f, "\t.long\t_%s_blob_end - _%s_blob_start /* totalsize */\n",
+	fprintf(f, "\t.long\t_%s_blob_abs_end - _%s_blob_start /* totalsize */\n",
 		symprefix, symprefix);
 	fprintf(f, "\t.long\t_%s_struct_start - _%s_blob_start /* off_dt_struct */\n",
 		symprefix, symprefix);
@@ -507,6 +511,15 @@ void dt_to_asm(FILE *f, struct boot_info *bi, int version, int boot_cpuid_phys)
 
 	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);
+	}
+	emit_label(f, symprefix, "blob_abs_end");
+
 	data_free(strbuf);
 }