Move library source into src sub-directory

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 48 insertions, 0 deletions

diff --git a/lib/tar/src/checksum.c b/lib/tar/src/checksum.c
new file mode 100644
index 0000000..6541373
--- /dev/null
+++ b/lib/tar/src/checksum.c
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * checksum.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+
+#include "tar/format.h"
+
+#include <stdio.h>
+
+static unsigned int get_checksum(const tar_header_t *hdr)
+{
+	const unsigned char *header_start = (const unsigned char *)hdr;
+	const unsigned char *chksum_start = (const unsigned char *)hdr->chksum;
+	const unsigned char *header_end = header_start + sizeof(*hdr);
+	const unsigned char *chksum_end = chksum_start + sizeof(hdr->chksum);
+	const unsigned char *p;
+	unsigned int chksum = 0;
+
+	for (p = header_start; p < chksum_start; p++)
+		chksum += *p;
+	for (; p < chksum_end; p++)
+		chksum += ' ';
+	for (; p < header_end; p++)
+		chksum += *p;
+	return chksum;
+}
+
+void update_checksum(tar_header_t *hdr)
+{
+	unsigned int chksum = get_checksum(hdr);
+
+	sprintf(hdr->chksum, "%06o", chksum);
+	hdr->chksum[6] = '\0';
+	hdr->chksum[7] = ' ';
+}
+
+bool is_checksum_valid(const tar_header_t *hdr)
+{
+	unsigned int calculated_chksum = get_checksum(hdr);
+	sqfs_u64 read_chksum;
+
+	if (read_octal(hdr->chksum, sizeof(hdr->chksum), &read_chksum))
+		return 0;
+	return read_chksum == calculated_chksum;
+}