--- /dev/null
+/* mpicoder.c - Coder for the external representation of MPIs
+ * Copyright (C) 1998, 1999 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include <linux/bitops.h>
+#include <asm-generic/bitops/count_zeros.h>
+#include "mpi-internal.h"
+
+#define MAX_EXTERN_MPI_BITS 16384
+
+/**
+ * mpi_read_raw_data - Read a raw byte stream as a positive integer
+ * @xbuffer: The data to read
+ * @nbytes: The amount of data to read
+ */
+MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes)
+{
+ const uint8_t *buffer = xbuffer;
+ int i, j;
+ unsigned nbits, nlimbs;
+ mpi_limb_t a;
+ MPI val = NULL;
+
+ while (nbytes > 0 && buffer[0] == 0) {
+ buffer++;
+ nbytes--;
+ }
+
+ nbits = nbytes * 8;
+ if (nbits > MAX_EXTERN_MPI_BITS) {
+ pr_info("MPI: mpi too large (%u bits)\n", nbits);
+ return NULL;
+ }
+ if (nbytes > 0)
+ nbits -= count_leading_zeros(buffer[0]);
+ else
+ nbits = 0;
+
+ nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
+ val = mpi_alloc(nlimbs);
+ if (!val)
+ return NULL;
+ val->nbits = nbits;
+ val->sign = 0;
+ val->nlimbs = nlimbs;
+
+ if (nbytes > 0) {
+ i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
+ i %= BYTES_PER_MPI_LIMB;
+ for (j = nlimbs; j > 0; j--) {
+ a = 0;
+ for (; i < BYTES_PER_MPI_LIMB; i++) {
+ a <<= 8;
+ a |= *buffer++;
+ }
+ i = 0;
+ val->d[j - 1] = a;
+ }
+ }
+ return val;
+}
+EXPORT_SYMBOL_GPL(mpi_read_raw_data);
+
+MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread)
+{
+ const uint8_t *buffer = xbuffer;
+ int i, j;
+ unsigned nbits, nbytes, nlimbs, nread = 0;
+ mpi_limb_t a;
+ MPI val = NULL;
+
+ if (*ret_nread < 2)
+ goto leave;
+ nbits = buffer[0] << 8 | buffer[1];
+
+ if (nbits > MAX_EXTERN_MPI_BITS) {
+ pr_info("MPI: mpi too large (%u bits)\n", nbits);
+ goto leave;
+ }
+ buffer += 2;
+ nread = 2;
+
+ nbytes = DIV_ROUND_UP(nbits, 8);
+ nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
+ val = mpi_alloc(nlimbs);
+ if (!val)
+ return NULL;
+ i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
+ i %= BYTES_PER_MPI_LIMB;
+ val->nbits = nbits;
+ j = val->nlimbs = nlimbs;
+ val->sign = 0;
+ for (; j > 0; j--) {
+ a = 0;
+ for (; i < BYTES_PER_MPI_LIMB; i++) {
+ if (++nread > *ret_nread) {
+ printk
+ ("MPI: mpi larger than buffer nread=%d ret_nread=%d\n",
+ nread, *ret_nread);
+ goto leave;
+ }
+ a <<= 8;
+ a |= *buffer++;
+ }
+ i = 0;
+ val->d[j - 1] = a;
+ }
+
+leave:
+ *ret_nread = nread;
+ return val;
+}
+EXPORT_SYMBOL_GPL(mpi_read_from_buffer);
+
+/****************
+ * Return an allocated buffer with the MPI (msb first).
+ * NBYTES receives the length of this buffer. Caller must free the
+ * return string (This function does return a 0 byte buffer with NBYTES
+ * set to zero if the value of A is zero. If sign is not NULL, it will
+ * be set to the sign of the A.
+ */
+void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
+{
+ uint8_t *p, *buffer;
+ mpi_limb_t alimb;
+ int i;
+ unsigned int n;
+
+ if (sign)
+ *sign = a->sign;
+ *nbytes = n = a->nlimbs * BYTES_PER_MPI_LIMB;
+ if (!n)
+ n++; /* avoid zero length allocation */
+ p = buffer = kmalloc(n, GFP_KERNEL);
+ if (!p)
+ return NULL;
+
+ for (i = a->nlimbs - 1; i >= 0; i--) {
+ alimb = a->d[i];
+#if BYTES_PER_MPI_LIMB == 4
+ *p++ = alimb >> 24;
+ *p++ = alimb >> 16;
+ *p++ = alimb >> 8;
+ *p++ = alimb;
+#elif BYTES_PER_MPI_LIMB == 8
+ *p++ = alimb >> 56;
+ *p++ = alimb >> 48;
+ *p++ = alimb >> 40;
+ *p++ = alimb >> 32;
+ *p++ = alimb >> 24;
+ *p++ = alimb >> 16;
+ *p++ = alimb >> 8;
+ *p++ = alimb;
+#else
+#error please implement for this limb size.
+#endif
+ }
+
+ /* this is sub-optimal but we need to do the shift operation
+ * because the caller has to free the returned buffer */
+ for (p = buffer; !*p && *nbytes; p++, --*nbytes)
+ ;
+ if (p != buffer)
+ memmove(buffer, p, *nbytes);
+
+ return buffer;
+}
+EXPORT_SYMBOL_GPL(mpi_get_buffer);
+
+/****************
+ * Use BUFFER to update MPI.
+ */
+int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign)
+{
+ const uint8_t *buffer = xbuffer, *p;
+ mpi_limb_t alimb;
+ int nlimbs;
+ int i;
+
+ nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
+ if (RESIZE_IF_NEEDED(a, nlimbs) < 0)
+ return -ENOMEM;
+ a->sign = sign;
+
+ for (i = 0, p = buffer + nbytes - 1; p >= buffer + BYTES_PER_MPI_LIMB;) {
+#if BYTES_PER_MPI_LIMB == 4
+ alimb = (mpi_limb_t) *p--;
+ alimb |= (mpi_limb_t) *p-- << 8;
+ alimb |= (mpi_limb_t) *p-- << 16;
+ alimb |= (mpi_limb_t) *p-- << 24;
+#elif BYTES_PER_MPI_LIMB == 8
+ alimb = (mpi_limb_t) *p--;
+ alimb |= (mpi_limb_t) *p-- << 8;
+ alimb |= (mpi_limb_t) *p-- << 16;
+ alimb |= (mpi_limb_t) *p-- << 24;
+ alimb |= (mpi_limb_t) *p-- << 32;
+ alimb |= (mpi_limb_t) *p-- << 40;
+ alimb |= (mpi_limb_t) *p-- << 48;
+ alimb |= (mpi_limb_t) *p-- << 56;
+#else
+#error please implement for this limb size.
+#endif
+ a->d[i++] = alimb;
+ }
+ if (p >= buffer) {
+#if BYTES_PER_MPI_LIMB == 4
+ alimb = *p--;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 8;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 16;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 24;
+#elif BYTES_PER_MPI_LIMB == 8
+ alimb = (mpi_limb_t) *p--;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 8;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 16;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 24;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 32;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 40;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 48;
+ if (p >= buffer)
+ alimb |= (mpi_limb_t) *p-- << 56;
+#else
+#error please implement for this limb size.
+#endif
+ a->d[i++] = alimb;
+ }
+ a->nlimbs = i;
+
+ if (i != nlimbs) {
+ pr_emerg("MPI: mpi_set_buffer: Assertion failed (%d != %d)", i,
+ nlimbs);
+ BUG();
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(mpi_set_buffer);
Code Review / kvmfornfv.git / blobdiff