mpi: Make gcry_mpi_print work with negative zeroes.

* mpi/mpicoder.c (gcry_mpi_print): Take care of negative zero.
(gcry_mpi_aprint): Allocate at least 1 byte.
* tests/t-convert.c: New.
* tests/Makefile.am (TESTS): Add t-convert.
--

Reported-by: Christian Fuchs
Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 160 insertions, 0 deletions

diff --git a/tests/t-convert.c b/tests/t-convert.c
new file mode 100644
index 00000000..b7f97fa3
--- /dev/null
+++ b/tests/t-convert.c
@@ -0,0 +1,160 @@
+/* t-convert.c  - Tests for mpi print and scna functions
+ * Copyright (C) 2013 g10 Code GmbH
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <stdarg.h>
+
+#include "../src/gcrypt-int.h"
+
+#define PGM "t-mpi-point"
+
+static const char *wherestr;
+static int verbose;
+static int debug;
+static int error_count;
+
+
+#define xmalloc(a)    gcry_xmalloc ((a))
+#define xcalloc(a,b)  gcry_xcalloc ((a),(b))
+#define xfree(a)      gcry_free ((a))
+#define pass() do { ; } while (0)
+
+static void
+show (const char *format, ...)
+{
+  va_list arg_ptr;
+
+  if (!verbose)
+    return;
+  fprintf (stderr, "%s: ", PGM);
+  va_start (arg_ptr, format);
+  vfprintf (stderr, format, arg_ptr);
+  va_end (arg_ptr);
+}
+
+static void
+fail (const char *format, ...)
+{
+  va_list arg_ptr;
+
+  fflush (stdout);
+  fprintf (stderr, "%s: ", PGM);
+  if (wherestr)
+    fprintf (stderr, "%s: ", wherestr);
+  va_start (arg_ptr, format);
+  vfprintf (stderr, format, arg_ptr);
+  va_end (arg_ptr);
+  error_count++;
+}
+
+static void
+die (const char *format, ...)
+{
+  va_list arg_ptr;
+
+  fflush (stdout);
+  fprintf (stderr, "%s: ", PGM);
+  if (wherestr)
+    fprintf (stderr, "%s: ", wherestr);
+  va_start (arg_ptr, format);
+  vfprintf (stderr, format, arg_ptr);
+  va_end (arg_ptr);
+  exit (1);
+}
+
+
+/* Check that mpi_print does not return a negative zero.  */
+static void
+negative_zero (void)
+{
+  gpg_error_t err;
+  gcry_mpi_t a;
+  char *buf;
+  void *bufaddr = &buf;
+  struct { const char *name; enum gcry_mpi_format format; } fmts[] =
+    {
+      { "STD", GCRYMPI_FMT_STD },
+      { "PGP", GCRYMPI_FMT_PGP },
+      { "SSH", GCRYMPI_FMT_SSH },
+      { "HEX", GCRYMPI_FMT_HEX },
+      { "USG", GCRYMPI_FMT_USG },
+      { NULL, 0 }
+    };
+  int i;
+
+  a = gcry_mpi_new (0);
+  for (i=0; fmts[i].name; i++)
+    {
+      err = gcry_mpi_aprint (fmts[i].format, bufaddr, NULL, a);
+      if (err)
+        fail ("error printing a zero as %s: %s\n",
+              fmts[i].name,gpg_strerror (err) );
+      else
+        gcry_free (buf);
+    }
+
+  /* With the current version of libgcrypt the next two statements
+     should set a to -0. */
+  gcry_mpi_sub_ui (a, a, 1);
+  gcry_mpi_add_ui (a, a, 1);
+
+  for (i=0; fmts[i].name; i++)
+    {
+      err = gcry_mpi_aprint (fmts[i].format, bufaddr, NULL, a);
+      if (err)
+        fail ("error printing a negative zero as %s: %s\n",
+              fmts[i].name,gpg_strerror (err) );
+      else
+        gcry_free (buf);
+    }
+
+  gcry_mpi_release (a);
+}
+
+
+
+
+int
+main (int argc, char **argv)
+{
+  if (argc > 1 && !strcmp (argv[1], "--verbose"))
+    verbose = 1;
+  else if (argc > 1 && !strcmp (argv[1], "--debug"))
+    verbose = debug = 1;
+
+  if (!gcry_check_version (GCRYPT_VERSION))
+    die ("version mismatch\n");
+
+  gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
+  gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
+  if (debug)
+    gcry_control (GCRYCTL_SET_DEBUG_FLAGS, 1u, 0);
+  gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
+
+  negative_zero ();
+
+  show ("All tests completed. Errors: %d\n", error_count);
+  return error_count ? 1 : 0;
+}