tools: Add a quoted-printable encoding function.

* tools/mime-maker.c (mime_maker_qp_encode): New.
* tools/t-mime-maker.c: New.
* tools/Makefile.am (TESTS): New.
(module_tests): Add the first test.

tools/t-mime-maker.c

@@ -0,0 +1,116 @@
+/* t-mime-maker.c - Module test for mime-maker.c
+ * Copyright (C) 2025 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 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.
+ *
+ * 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 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 <https://www.gnu.org/licenses/>.
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include "../common/util.h"
+#include "../common/init.h"
+#include "mime-maker.h"
+
+
+static int verbose;
+
+
+
+static void
+test_qp_encode (void)
+{
+  static struct
+  {
+    const char *plain;
+    const char *encoded;
+  } samples[] =
+    {
+      { "",
+        ""
+      },{
+        "From someone\n"
+        " I received this mail\n",
+        "=46rom someone\n"
+        " I received this mail\n"
+      },{
+        " From someone\n",
+        " From someone\n"
+      },{
+        "Foo\n"
+        ".\n",
+        "Foo\n"
+        "=2E\n"
+      },{
+        "Foo\n"
+        ".",
+        "Foo\n"
+        "=2E"
+      },{
+        "Hello ÄÖܧäöüß my dear umlauts",
+        "Hello =C3=84=C3=96=C3=9C=C2=A7=C3=A4=C3=B6=C3=BC=C3=9F "
+        "my dear umlauts"
+      },{
+        "👀\tⒶ",
+        "=F0=9F=91=80\t=E2=92=B6"
+      }
+    };
+  int idx;
+  char *result;
+  int oops = 0;
+
+  for (idx=0; idx < DIM (samples); idx++)
+    {
+      result = mime_maker_qp_encode (samples[idx].plain);
+      if (!result)
+        {
+          log_error ("%s:test %d: error: %s\n",
+                     __func__, idx, strerror (errno));
+          exit (1);
+        }
+      if (strcmp (samples[idx].encoded, result))
+        {
+          log_error ("%s:test %d: error\nwant ===>%s<===\n got ===>%s<===\n",
+                     __func__, idx, samples[idx].plain, result);
+          oops = 1;
+        }
+    }
+
+  if (oops)
+    exit (1);
+}
+
+
+int
+main (int argc, char **argv)
+{
+  log_set_prefix ("t-mime-maker", GPGRT_LOG_WITH_PREFIX);
+  init_common_subsystems (&argc, &argv);
+
+  if (argc)
+    { argc--; argv++; }
+  if (argc && !strcmp (argv[0], "--verbose"))
+    {
+      verbose = 1;
+      argc--; argv++;
+    }
+
+  test_qp_encode ();
+
+  return 0;
+}