From cdccc69c62579b0c13b35fad0728079652b8f3c9 Mon Sep 17 00:00:00 2001 From: David Oberhollenzer Date: Tue, 31 Jan 2023 11:21:30 +0100 Subject: Move library source into src sub-directory Signed-off-by: David Oberhollenzer --- lib/tar/src/checksum.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 lib/tar/src/checksum.c (limited to 'lib/tar/src/checksum.c') 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 + */ +#include "config.h" + +#include "tar/format.h" + +#include + +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; +} -- cgit v1.2.3