Import gcrypt public-key cryptography and implement signature checking.

grub-core/lib/libgcrypt/mpi/mpi-cmp.c

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+/* mpi-cmp.c  -  MPI functions
+ * Copyright (C) 1998, 1999, 2001, 2002, 2005 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser 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 <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "mpi-internal.h"
+
+int
+gcry_mpi_cmp_ui (gcry_mpi_t u, unsigned long v)
+{
+  mpi_limb_t limb = v;
+
+  _gcry_mpi_normalize (u);
+
+  /* Handle the case that U contains no limb.  */
+  if (u->nlimbs == 0)
+    return -(limb != 0);
+
+  /* Handle the case that U is negative.  */
+  if (u->sign)
+    return -1;
+
+  if (u->nlimbs == 1)
+    {
+      /* Handle the case that U contains exactly one limb.  */
+
+      if (u->d[0] > limb)
+	return 1;
+      if (u->d[0] < limb)
+	return -1;
+      return 0;
+    }
+  else
+    /* Handle the case that U contains more than one limb.  */
+    return 1;
+}
+
+
+int
+gcry_mpi_cmp (gcry_mpi_t u, gcry_mpi_t v)
+{
+  mpi_size_t usize;
+  mpi_size_t vsize;
+  int cmp;
+
+  if (mpi_is_opaque (u) || mpi_is_opaque (v))
+    {
+      if (mpi_is_opaque (u) && !mpi_is_opaque (v))
+        return -1;
+      if (!mpi_is_opaque (u) && mpi_is_opaque (v))
+        return 1;
+      if (!u->sign && !v->sign)
+        return 0; /* Empty buffers are identical.  */
+      if (u->sign < v->sign)
+        return -1;
+      if (u->sign > v->sign)
+        return 1;
+      return memcmp (u->d, v->d, (u->sign+7)/8);
+    }
+  else
+    {
+      _gcry_mpi_normalize (u);
+      _gcry_mpi_normalize (v);
+
+      usize = u->nlimbs;
+      vsize = v->nlimbs;
+
+      /* Compare sign bits.  */
+
+      if (!u->sign && v->sign)
+        return 1;
+      if (u->sign && !v->sign)
+        return -1;
+
+      /* U and V are either both positive or both negative.  */
+
+      if (usize != vsize && !u->sign && !v->sign)
+        return usize - vsize;
+      if (usize != vsize && u->sign && v->sign)
+        return vsize + usize;
+      if (!usize )
+        return 0;
+      if (!(cmp = _gcry_mpih_cmp (u->d, v->d, usize)))
+        return 0;
+      if ((cmp < 0?1:0) == (u->sign?1:0))
+        return 1;
+    }
+  return -1;
+}