format: Reduce the length of the signature header

Since a single signature can only be up to 2048 bytes long,
we do not need 32 bits to tell us how many of those bytes
are being used.
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

src/database.c

@@ -274,8 +274,8 @@ static int loc_database_read_header_v1(struct loc_database* db) {
 	db->description = be32toh(header.description);
 	db->license     = be32toh(header.license);
 
-	db->signature1_length = be32toh(header.signature1_length);
-	db->signature2_length = be32toh(header.signature2_length);
+	db->signature1_length = be16toh(header.signature1_length);
+	db->signature2_length = be16toh(header.signature2_length);
 
 	// Read signatures
 	if (db->signature1_length) {

src/loc/format.h

@@ -75,17 +75,14 @@ struct loc_database_header_v1 {
 	uint32_t pool_offset;
 	uint32_t pool_length;
 
-	// Some padding
-	char padding1[2];
-
 	// Signatures
-	uint32_t signature1_length;
-	uint32_t signature2_length;
+	uint16_t signature1_length;
+	uint16_t signature2_length;
 	char signature1[LOC_SIGNATURE_MAX_LENGTH];
 	char signature2[LOC_SIGNATURE_MAX_LENGTH];
 
 	// Add some padding for future extensions
-	char padding2[32];
+	char padding[32];
 };
 
 struct loc_database_network_node_v1 {

src/writer.c

@@ -531,7 +531,7 @@ static int loc_database_write_countries(struct loc_writer* writer,
 static int loc_writer_create_signature(struct loc_writer* writer,
 		struct loc_database_header_v1* header, FILE* f, EVP_PKEY* private_key,
 		char* signature, size_t* length) {
-	DEBUG(writer->ctx, "Signing database...\n");
+	DEBUG(writer->ctx, "Creating signature...\n");
 
 	// Read file from the beginning
 	rewind(f);
@@ -649,8 +649,7 @@ LOC_EXPORT int loc_writer_write(struct loc_writer* writer, FILE* f, enum loc_dat
 	header.signature2_length = 0;
 
 	// Clear the padding
-	memset(header.padding1, '\0', sizeof(header.padding1));
-	memset(header.padding2, '\0', sizeof(header.padding2));
+	memset(header.padding, '\0', sizeof(header.padding));
 
 	int r;
 	off_t offset = 0;
@@ -718,13 +717,19 @@ LOC_EXPORT int loc_writer_write(struct loc_writer* writer, FILE* f, enum loc_dat
 
 	// Copy the signatures into the header
 	if (writer->signature1_length) {
+		DEBUG(writer->ctx, "Copying first signature of %zu byte(s)\n",
+			writer->signature1_length);
+
 		memcpy(header.signature1, writer->signature1, writer->signature1_length);
-		header.signature1_length = htobe32(writer->signature1_length);
+		header.signature1_length = htobe16(writer->signature1_length);
 	}
 
 	if (writer->signature2_length) {
+		DEBUG(writer->ctx, "Copying second signature of %zu byte(s)\n",
+			writer->signature1_length);
+
 		memcpy(header.signature2, writer->signature2, writer->signature2_length);
-		header.signature2_length = htobe32(writer->signature2_length);
+		header.signature2_length = htobe16(writer->signature2_length);
 	}
 
 	// Write the header