static int file_read_header()

in lang/c/src/datafile.c [241:326]

• 76 lines of code
• 14 McCabe index (conditional complexity)

static int file_read_header(avro_reader_t reader,
			    avro_schema_t * writers_schema, avro_codec_t codec,
			    char *sync, int synclen)
{
	int rval;
	avro_schema_t meta_schema;
	avro_schema_t meta_values_schema;
	avro_value_iface_t *meta_iface;
	avro_value_t meta;
	char magic[4];
	avro_value_t codec_val;
	avro_value_t schema_bytes;
	const void *p;
	size_t len;

	check(rval, avro_read(reader, magic, sizeof(magic)));
	if (magic[0] != 'O' || magic[1] != 'b' || magic[2] != 'j'
	    || magic[3] != 1) {
		avro_set_error("Incorrect Avro container file magic number");
		return EILSEQ;
	}

	meta_values_schema = avro_schema_bytes();
	meta_schema = avro_schema_map(meta_values_schema);
	meta_iface = avro_generic_class_from_schema(meta_schema);
	if (meta_iface == NULL) {
		return EILSEQ;
	}
	check(rval, avro_generic_value_new(meta_iface, &meta));
	rval = avro_value_read(reader, &meta);
	if (rval) {
		avro_prefix_error("Cannot read file header: ");
		return EILSEQ;
	}
	avro_schema_decref(meta_schema);

	rval = avro_value_get_by_name(&meta, "avro.codec", &codec_val, NULL);
	if (rval) {
		if (avro_codec(codec, NULL) != 0) {
			avro_set_error("Codec not specified in header and unable to set 'null' codec");
			avro_value_decref(&meta);
			return EILSEQ;
		}
	} else {
		const void *buf;
		size_t size;
		char codec_name[11];

		avro_type_t type = avro_value_get_type(&codec_val);

		if (type != AVRO_BYTES) {
			avro_set_error("Value type of codec is unexpected");
			avro_value_decref(&meta);
			return EILSEQ;
		}

		avro_value_get_bytes(&codec_val, &buf, &size);
		memset(codec_name, 0, sizeof(codec_name));
		strncpy(codec_name, (const char *) buf, size < 10 ? size : 10);

		if (avro_codec(codec, codec_name) != 0) {
			avro_set_error("File header contains an unknown codec");
			avro_value_decref(&meta);
			return EILSEQ;
		}
	}

	rval = avro_value_get_by_name(&meta, "avro.schema", &schema_bytes, NULL);
	if (rval) {
		avro_set_error("File header doesn't contain a schema");
		avro_value_decref(&meta);
		return EILSEQ;
	}

	avro_value_get_bytes(&schema_bytes, &p, &len);
	rval = avro_schema_from_json_length((const char *) p, len, writers_schema);
	if (rval) {
		avro_prefix_error("Cannot parse file header: ");
		avro_value_decref(&meta);
		return rval;
	}

	avro_value_decref(&meta);
	avro_value_iface_decref(meta_iface);
	return avro_read(reader, sync, synclen);
}