gpg: Move S2K encoding function to a shared file.

* g10/passphrase.c (encode_s2k_iterations): Move function to ...
* common/openpgp-s2k.c: new file.  Remove default intialization code.
* common/openpgpdefs.h (S2K_DECODE_COUNT): New to keep only one copy.
* g10/call-agent.c (agent_get_s2k_count): Change to return the count
and print an error.
* agent/protect.c: Include openpgpdefs.h
* g10/card-util.c (gen_kdf_data): Adjust for changes
* g10/gpgcompose.c: Include call-agent.h.
(sk_esk): Adjust for changes.
* g10/passphrase (passphrase_to_dek): Adjust for changes.
* g10/main.h (S2K_DECODE_COUNT): Remove macro.

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

common/Makefile.am

@@ -83,7 +83,7 @@ common_sources = \
 	localename.c \
 	session-env.c session-env.h \
 	userids.c userids.h \
-	openpgp-oid.c \
+	openpgp-oid.c openpgp-s2k.c \
 	ssh-utils.c ssh-utils.h \
 	agent-opt.c \
 	helpfile.c \

common/openpgp-s2k.c

@@ -0,0 +1,67 @@
+/* openpgp-s2ks.c - OpenPGP S2K helper functions
+ * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
+ *               2005, 2006 Free Software Foundation, Inc.
+ * Copyright (C) 2010, 2019 g10 Code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either
+ *
+ *   - the GNU Lesser General Public License as published by the Free
+ *     Software Foundation; either version 3 of the License, or (at
+ *     your option) any later version.
+ *
+ * or
+ *
+ *   - 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.
+ *
+ * or both in parallel, as here.
+ *
+ * This file 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <ctype.h>
+#include <assert.h>
+
+#include "util.h"
+#include "openpgpdefs.h"
+
+
+/* Pack an s2k iteration count into the form specified in RFC-48800.
+ * If we're in between valid values, round up.  */
+unsigned char
+encode_s2k_iterations (int iterations)
+{
+  unsigned char c=0;
+  unsigned char result;
+  unsigned int count;
+
+  if (iterations <= 1024)
+    return 0;  /* Command line arg compatibility.  */
+
+  if (iterations >= 65011712)
+    return 255;
+
+  /* Need count to be in the range 16-31 */
+  for (count=iterations>>6; count>=32; count>>=1)
+    c++;
+
+  result = (c<<4)|(count-16);
+
+  if (S2K_DECODE_COUNT(result) < iterations)
+    result++;
+
+  return result;
+}

common/openpgpdefs.h

@@ -197,4 +197,14 @@ typedef enum
 compress_algo_t;
 
 
+
+
+/* Decode an rfc4880 encoded S2K count.  */
+#define S2K_DECODE_COUNT(_val) ((16ul + ((_val) & 15)) << (((_val) >> 4) + 6))
+
+
+/*--openpgp-s2k.c --*/
+unsigned char encode_s2k_iterations (int iterations);
+
+
 #endif /*GNUPG_COMMON_OPENPGPDEFS_H*/

common/ttyio.c

@@ -564,6 +564,8 @@ do_get( const char *prompt, int hidden )
 }
 
 
+
+/* Note: This function never returns NULL. */
 char *
 tty_get( const char *prompt )
 {