62d5a1e56f
function old new delta chksum_and_xwrite_tar_header - 99 +99 writeheader 280 199 -81 chksum_and_xwrite 102 - -102 ------------------------------------------------------------------------------ (add/remove: 2/1 grow/shrink: 0/1 up/down: 99/-183) Total: -84 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
36 lines
1.1 KiB
C
36 lines
1.1 KiB
C
/*
|
|
* Copyright (C) 2021 Denys Vlasenko <vda.linux@googlemail.com>
|
|
*
|
|
* Licensed under GPLv2, see file LICENSE in this source tree.
|
|
*/
|
|
//kbuild:lib-$(CONFIG_FEATURE_TAR_CREATE) += chksum_and_xwrite_tar_header.o
|
|
//kbuild:lib-$(CONFIG_SMEMCAP) += chksum_and_xwrite_tar_header.o
|
|
|
|
#include "libbb.h"
|
|
#include "bb_archive.h"
|
|
|
|
void FAST_FUNC chksum_and_xwrite_tar_header(int fd, struct tar_header_t *hp)
|
|
{
|
|
/* POSIX says that checksum is done on unsigned bytes
|
|
* (Sun and HP-UX gets it wrong... more details in
|
|
* GNU tar source) */
|
|
const unsigned char *cp;
|
|
int chksum, size;
|
|
|
|
strcpy(hp->magic, "ustar ");
|
|
|
|
/* Calculate and store the checksum (the sum of all of the bytes of
|
|
* the header). The checksum field must be filled with blanks for the
|
|
* calculation. The checksum field is formatted differently from the
|
|
* other fields: it has 6 digits, a NUL, then a space -- rather than
|
|
* digits, followed by a NUL like the other fields... */
|
|
memset(hp->chksum, ' ', sizeof(hp->chksum));
|
|
cp = (const unsigned char *) hp;
|
|
chksum = 0;
|
|
size = sizeof(*hp);
|
|
do { chksum += *cp++; } while (--size);
|
|
sprintf(hp->chksum, "%06o", chksum);
|
|
|
|
xwrite(fd, hp, sizeof(*hp));
|
|
}
|