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get_header_tar: shrink 6->64 sign extension code

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function                                             old     new   delta
getOctal                                             125     107     -18

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2011-10-19 14:51:12 +02:00
parent 9c28fb8d28
commit f74f280a14
1 changed files with 4 additions and 4 deletions
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8
archival/libarchive/get_header_tar.c
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@ -79,10 +79,10 @@ static unsigned long long getOctal(char *str, int len)
*
* NB: tarballs with NEGATIVE unix times encoded that way were seen!
*/
v = first;
/* Sign-extend using 6th bit: */
v <<= sizeof(unsigned long long)*8 - 7;
v = (long long)v >> (sizeof(unsigned long long)*8 - 7);
/* Sign-extend 7bit 'first' to 64bit 'v' (that is, using 6th bit as sign): */
first <<= 1;
first >>= 1; /* now 7th bit = 6th bit */
v = first; /* sign-extend 8 bits to 64 */
while (--len != 0)
v = (v << 8) + (unsigned char) *str++;
}