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MPI: Fix mpi_read_buffer

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Change mpi_read_buffer to return a number without leading zeros
so that mpi_read_buffer and mpi_get_buffer return the same thing.

Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Tadeusz Struk 2015-08-24 07:52:14 -07:00 committed by Herbert Xu
parent 55e8dba1ac
commit 0f74fbf77d
1 changed files with 25 additions and 13 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

38
lib/mpi/mpicoder.c
View file

@ -146,18 +146,25 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
uint8_t *p;
mpi_limb_t alimb;
unsigned int n = mpi_get_size(a);
int i;
int i, lzeros = 0;
if (buf_len < n || !buf)
if (buf_len < n || !buf || !nbytes)
return -EINVAL;
if (sign)
*sign = a->sign;
if (nbytes)
*nbytes = n;
p = (void *)&a->d[a->nlimbs] - 1;
for (i = a->nlimbs * sizeof(alimb) - 1; i >= 0; i--, p--) {
if (!*p)
lzeros++;
else
break;
}
p = buf;
*nbytes = n - lzeros;
for (i = a->nlimbs - 1; i >= 0; i--) {
alimb = a->d[i];
@ -178,6 +185,19 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
#else
#error please implement for this limb size.
#endif
if (lzeros > 0) {
if (lzeros >= sizeof(alimb)) {
p -= sizeof(alimb);
} else {
mpi_limb_t *limb1 = (void *)p - sizeof(alimb);
mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
+ lzeros;
*limb1 = *limb2;
p -= lzeros;
}
lzeros -= sizeof(alimb);
}
}
return 0;
}
@ -197,7 +217,7 @@ EXPORT_SYMBOL_GPL(mpi_read_buffer);
*/
void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
{
uint8_t *buf, *p;
uint8_t *buf;
unsigned int n;
int ret;
@ -220,14 +240,6 @@ void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
kfree(buf);
return NULL;
}
/* this is sub-optimal but we need to do the shift operation
* because the caller has to free the returned buffer */
for (p = buf; !*p && *nbytes; p++, --*nbytes)
;
if (p != buf)
memmove(buf, p, *nbytes);
return buf;
}
EXPORT_SYMBOL_GPL(mpi_get_buffer);