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(tar_checksum): sync with GNU tar b5db9788306d45cd9432fda71236f07b8a214212. 

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
This commit is contained in:
Andrew Borodin 2020-06-28 16:42:26 +03:00
parent c4e20d3176
commit 4ae197e788
1 changed files with 28 additions and 29 deletions
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57
src/vfs/tar/tar.c
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@ -412,45 +412,44 @@ tar_skip_n_records (struct vfs_s_super *archive, int tard, size_t n)
/* --------------------------------------------------------------------------------------------- */
/** Check header checksum.
*/
static read_header
tar_checksum (const union block *header)
{
long recsum;
long signed_sum = 0;
long sum = 0;
int i;
size_t i;
int unsigned_sum = 0; /* the POSIX one :-) */
int signed_sum = 0; /* the Sun one :-( */
int recorded_sum;
long parsed_sum;
const char *p = header->buffer;
recsum = tar_from_oct (8, header->header.chksum);
for (i = sizeof (*header); --i >= 0;)
for (i = sizeof (*header); i-- != 0;)
{
/*
* We can't use unsigned char here because of old compilers,
* e.g. V7.
*/
signed_sum += *p;
sum += 0xFF & *p++;
unsigned_sum += (unsigned char) *p;
signed_sum += (signed char) (*p++);
}
/* Adjust checksum to count the "chksum" field as blanks. */
for (i = sizeof (header->header.chksum); --i >= 0;)
{
sum -= 0xFF & header->header.chksum[i];
signed_sum -= (char) header->header.chksum[i];
}
sum += ' ' * sizeof (header->header.chksum);
signed_sum += ' ' * sizeof (header->header.chksum);
/*
* This is a zeroed block... whole block is 0's except
* for the 8 blanks we faked for the checksum field.
*/
if (sum == 8 * ' ')
if (unsigned_sum == 0)
return HEADER_ZERO_BLOCK;
if (sum != recsum && signed_sum != recsum)
/* Adjust checksum to count the "chksum" field as blanks. */
for (i = sizeof (header->header.chksum); i-- != 0;)
{
unsigned_sum -= (unsigned char) header->header.chksum[i];
signed_sum -= (signed char) (header->header.chksum[i]);
}
unsigned_sum += ' ' * sizeof (header->header.chksum);
signed_sum += ' ' * sizeof (header->header.chksum);
parsed_sum = tar_from_oct (8, header->header.chksum);
if (parsed_sum == -1)
return HEADER_FAILURE;
recorded_sum = parsed_sum;
if (unsigned_sum != recorded_sum && signed_sum != recorded_sum)
return HEADER_FAILURE;
return HEADER_SUCCESS;