New mailutils subcommand: maildir_fixup

The subcommand converts names in maildirs created by earlier versions of
mailutils to the new format.

* NEWS: Update.
* doc/texinfo/programs/mailutils.texi: Document maildir_fixup
* mu/libexec/Makefile.am: Build maildir_fixup subcommand.
* mu/libexec/maildir_fixup.c: New file.
* mu/libexec/mu.h (common_options): New extern.

* include/mailutils/cli.h (MU_CLI_OPTION_CONF_PROGNAME): New constant.
* libmailutils/cli/simple.c (MU_CLI_OPTION_PROG_NAME)
(MU_CLI_OPTION_PROG_NAME)
(MU_CLI_OPTION_PROG_DOC)
(MU_CLI_OPTION_BUG_ADDRESS)
(MU_CLI_OPTION_PACKAGE_URL)
(MU_CLI_OPTION_EXTRA_INFO)
(MU_CLI_OPTION_HELP_HOOK)
(MU_CLI_OPTION_VERSION_HOOK)
(MU_CLI_OPTION_PROG_DOC_HOOK)
(MU_CLI_OPTION_NEGATION)
(MU_CLI_OPTION_SPECIAL_ARGS): Allow for NULL argument.
(MU_CLI_OPTION_CONF_PROGNAME): New code

8 files changed, 333 insertions, 18 deletions

diff --git a/NEWS b/NEWS
index e5531a6ad..46360a722 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,4 @@
-GNU mailutils NEWS -- history of user-visible changes. 2020-11-10
+GNU mailutils NEWS -- history of user-visible changes. 2020-11-17
 See the end of file for copying conditions.
 
 Please send mailutils bug reports to <bug-mailutils@gnu.org>.
@@ -18,6 +18,16 @@ incorrect flag mapping and fixes it if so.  If the mailbox is opened
 in read-write mode, the changes are immediately propagated to the disk
 storage.
 
+An auxiliary tool `maildir_fixup' is provided to fix up all maildirs
+in given folders recursively.  The tool can be used if you operate a
+site with a large number of mailboxes in maildir format and wish to
+convert all of them at once.  It is implemented as a subcommand of the
+`mailutils' utility.  Example usage:
+
+   mailutils maildir_fixup /var/spool/maildirs
+
+* Fix persistency of UIDs for all mailbox formats
+
 * Fix message ordering in maildir.
 
 * Fix parsing of IMAP ranges
diff --git a/doc/texinfo/programs/mailutils.texi b/doc/texinfo/programs/mailutils.texi
index d4769b85e..176d897df 100644
--- a/doc/texinfo/programs/mailutils.texi
+++ b/doc/texinfo/programs/mailutils.texi
@@ -26,6 +26,7 @@ with Mailutils.
 * mailutils imap::                IMAP4 client shell.
 * mailutils send::                Send a message.
 * mailutils smtp::                Run a SMTP session.
+* mailutils maildir_fixup::       Fix-up maildirs created by versions prior to 3.10.90
 @end menu
 
 @node mailutils invocation syntax
@@ -1450,3 +1451,59 @@ message: send, edit, or quit (discard) it.
 Internal commands are the same as in @code{pop} shell: @xref{mailutils
 pop, Internal commands}.
 
+@node mailutils maildir_fixup
+@subsection mailutils maildir_fixup
+
+This command fixes attributes and UID assignments in @samp{maildir}
+mailboxes created by mailutils versions prior to 3.10.90.
+
+Attribute flags used in @samp{maildir} mailboxes by these versions of
+mailutils were a bit different from those described in the original
+description of the @samp{maildir} format@footnote{@uref{http://cr.yp.to/proto/maildir.html}}
+and those used by another implementations.  The discrepancy has been
+reported in the Mailutils bug tracker@footnote{@uref{http://savannah.gnu.org/bugs/?56428}}
+and was fixed in version 3.10.90.  Along with this fix, measures has
+been taken to ensure persistence of UID assignments between different
+sessions.  Starting from version 3.10.90, whenever @command{mailutils}
+library opens a maildir mailbox, it determines the version that
+created it.  If the mailbox is writable and the library determines
+that the mailbox is affected by the two problems described above, it
+fixes the mailbox on the fly.  This process is completely transparent
+to the user.
+
+If you operate a site with a large number of mailboxes in
+@samp{maildir} formats, you may choose to fix up all of them at once.
+That's what the @command{maildir_fixup} command is for.  It takes one
+or more directory names as its arguments and recursively scans these
+directories in search for @samp{maildir} mailboxes.  Each mailbox
+found is analyzed and a fix-up is performed, if necessary.  If a
+mailbox is already in the new format, it remains untouched.
+
+The following options modify the program's behavior:
+
+@table @option
+@item -v
+@itemx --verbose
+List each maildir name before processing it.
+
+@item -n
+@itemx --dry-run
+Don't touch maildirs, just print their names,
+@end table
+
+The @command{maildir_fixup} tool reads main mailutils configuration
+file by default.  It looks for program-specific settings in the
+section @samp{program maildir_fixup}.  If the @code{include} statement
+is present that has a directory name as its argument, the file
+@file{maildir_fixup} is looked up in that directory and parsed, if
+present.
+
+The program uses the following configuration statements:
+
+@multitable @columnfractions 0.3 0.6
+@headitem Statement @tab Reference
+@item debug         @tab @xref{debug statement}.
+@item locking       @tab @xref{locking statement}.
+@item mandatory-locking @tab @FIXME-xref{mandatory-locking statement}.
+@end multitable
+
diff --git a/include/mailutils/cli.h b/include/mailutils/cli.h
index 9d2afc806..18ce2c341 100644
--- a/include/mailutils/cli.h
+++ b/include/mailutils/cli.h
@@ -89,12 +89,14 @@ enum
 
     /* Argument: struct mu_cfg_param * 
      * Description: Supplies configuration definitions.
+     * NULL argument is a no-op.
      * Ref: cfg in struct mu_cli_setup
      */
     MU_CLI_OPTION_CONFIG,
 
     /* Argument: char **
      * Description: NULL-terminated array of capability strings.
+     * NULL argument is a no-op.
      * Ref: capa argument to mu_cli and mu_cli_ext.
      */
     MU_CLI_OPTION_CAPABILITIES,
@@ -167,6 +169,7 @@ enum
     /* Argument: char const *
      * Description: Override the name of the program to use in error
      * messages.
+     * NULL argument is a no-op.
      * Ref: MU_PARSEOPT_PROG_NAME flag in opt.h
      */
     MU_CLI_OPTION_PROG_NAME,      
@@ -174,6 +177,7 @@ enum
     /* Argument: char const *
      * Description: Documentation string for the program. It will be
      * displayed on the line following the usage summary.
+     * NULL argument is a no-op.
      * Ref: MU_PARSEOPT_PROG_DOC
      */
     MU_CLI_OPTION_PROG_DOC,       
@@ -186,6 +190,7 @@ enum
      *    Usage: foo A B
      *
      * Multiple instances are allowed.
+     * NULL argument is a no-op.
      * Ref: MU_PARSEOPT_PROG_ARGS flag in opt.h
      */
     MU_CLI_OPTION_PROG_ARGS,      
@@ -198,12 +203,14 @@ enum
 
     /* Argument: char const *
      * Description: Sets the PACKAGE_NAME.
+     * NULL argument is a no-op.
      * Ref: MU_PARSEOPT_PACKAGE_NAME in opt.h
      */
     MU_CLI_OPTION_PACKAGE_NAME,   
 
     /* Argument: char const *
      * Description: URL of the package.
+     * NULL argument is a no-op.
      * Ref: MU_PARSEOPT_PACKAGE_URL in opt.h
      */
     MU_CLI_OPTION_PACKAGE_URL,    
@@ -211,6 +218,7 @@ enum
     /* Argument: char const *
      * Description: Extra help information.  This will be displayed after
      * the option list.
+     * NULL argument is a no-op.
      * Ref: MU_PARSEOPT_EXTRA_INFO in opt.h
      */
     MU_CLI_OPTION_EXTRA_INFO,     
@@ -218,6 +226,7 @@ enum
     /* Argument: void (*) (struct mu_parseopt *, mu_stream_t)
      * Description: Pointer to a function to be called as a part of the
      * --help option handling, after outputting the option list.
+     * NULL argument is a no-op.
      * Ref: po_help_hook member of struct mu_parseopt and the
      * MU_PARSEOPT_HELP_HOOK flag in opt.h
      */
@@ -243,7 +252,9 @@ enum
      * --help option handling.  This function will be called after printing
      * initial program description (see MU_CLI_OPTION_PROG_DOC) and before
      * printing the option summary.
-     * Ref:
+     * NULL argument is a no-op.
+     * Ref: po_prog_doc_hook member of struct mu_parseopt and the
+     * MU_PARSEOPT_PROG_DOC_HOOK in opt.h
      */
     MU_CLI_OPTION_PROG_DOC_HOOK,  
 
@@ -256,6 +267,7 @@ enum
 
     /* Argument: char const *
      * Description: Prefix that negates the value of a boolean option.
+     * NULL argument is a no-op.
      * Ref: po_negation member of struct mu_parseopt and the
      * MU_PARSEOPT_NEGATION flag in opt.h
      */
@@ -264,6 +276,7 @@ enum
     /* Argument: char const *
      * Description: Descriptive names of special arguments. If given, this
      * will be printed in short usage summary after the regular options.
+     * NULL argument is a no-op.
      * Ref: The po_special_args member of struct mu_parseopt and the
      * MU_PARSEOPT_SPECIAL_ARGS flag in opt.h
      */
@@ -289,7 +302,17 @@ enum
      * from the command line.
      * Ref: MU_CFHINT_NO_CONFIG_OVERRIDE flag in cfg.h
      */
-    MU_CLI_OPTION_CONF_NO_OVERRIDE
+    MU_CLI_OPTION_CONF_NO_OVERRIDE,
+
+    /* Argument: char const *
+     * Description: Identifier of the per-program section in the configuration
+     * file or name of the per-program configuration file (used when
+     * processing the "include" statement with a directory name as its
+     * argument).  If NULL or not set, program name is used.  See also
+     * MU_CLI_OPTION_PROG_NAME.
+     * Ref: MU_CFHINT_PROGRAM flag in cfg.h
+     */
+    MU_CLI_OPTION_CONF_PROGNAME,
   };
 
 void mu_cli_simple (int argc, char **argv, ...);
diff --git a/lib/manlock.c b/lib/manlock.c
index a093a1926..f50e16343 100644
--- a/lib/manlock.c
+++ b/lib/manlock.c
@@ -237,10 +237,6 @@ manlock_cfg_init ()
   mu_create_canned_section ("mandatory-locking", &section);
   mu_cfg_section_add_params (section, manlock_param);
 }
-
-
-
-  
 
 int
 manlock_lock (mu_mailbox_t mbox)
diff --git a/libmailutils/cli/simple.c b/libmailutils/cli/simple.c
index 0daef170d..20adcc11b 100644
--- a/libmailutils/cli/simple.c
+++ b/libmailutils/cli/simple.c
@@ -117,13 +117,15 @@ mu_cli_simple (int argc, char **argv, ...)
 	  break;
 	  
 	case MU_CLI_OPTION_PROG_NAME:      
-	  pohint.po_flags |= MU_PARSEOPT_PROG_NAME;
 	  pohint.po_prog_name = va_arg (ap, char *);
+          if (pohint.po_prog_name)
+	    pohint.po_flags |= MU_PARSEOPT_PROG_NAME;
 	  break;
 
 	case MU_CLI_OPTION_PROG_DOC:       
-	  pohint.po_flags |= MU_PARSEOPT_PROG_DOC;
 	  pohint.po_prog_doc = va_arg (ap, char *);
+          if (pohint.po_prog_doc)
+	    pohint.po_flags |= MU_PARSEOPT_PROG_DOC;
 	  break;
 
 	case MU_CLI_OPTION_PROG_ARGS:
@@ -137,51 +139,60 @@ mu_cli_simple (int argc, char **argv, ...)
 	  break;
 
 	case MU_CLI_OPTION_BUG_ADDRESS:
-	  pohint.po_flags |= MU_PARSEOPT_BUG_ADDRESS;
 	  pohint.po_bug_address = va_arg (ap, char *);
+          if (pohint.po_bug_address)
+	    pohint.po_flags |= MU_PARSEOPT_BUG_ADDRESS;
 	  break;
 	  
 	case MU_CLI_OPTION_PACKAGE_NAME:
-	  pohint.po_flags |= MU_PARSEOPT_PACKAGE_NAME;
 	  pohint.po_package_name = va_arg (ap, char *);
+          if (pohint.po_package_name)
+	    pohint.po_flags |= MU_PARSEOPT_PACKAGE_NAME;
 	  break;
 	  
 	case MU_CLI_OPTION_PACKAGE_URL:
-	  pohint.po_flags |= MU_PARSEOPT_PACKAGE_URL;
 	  pohint.po_package_url = va_arg (ap, char *);
+          if (pohint.po_package_url)
+	    pohint.po_flags |= MU_PARSEOPT_PACKAGE_URL;
 	  break;
 	  
 	case MU_CLI_OPTION_EXTRA_INFO:
-	  pohint.po_flags |= MU_PARSEOPT_EXTRA_INFO;
 	  pohint.po_extra_info = va_arg (ap, char *);
+          if (pohint.po_extra_info)
+	    pohint.po_flags |= MU_PARSEOPT_EXTRA_INFO;
 	  break;
 	  
 	case MU_CLI_OPTION_HELP_HOOK:
-	  pohint.po_flags |= MU_PARSEOPT_HELP_HOOK;
 	  pohint.po_help_hook =
 	    va_arg (ap, void (*) (struct mu_parseopt *, mu_stream_t));
+          if (pohint.po_help_hook)
+	    pohint.po_flags |= MU_PARSEOPT_HELP_HOOK;
 	  break;
 	  
 	case MU_CLI_OPTION_VERSION_HOOK:
-	  pohint.po_flags |= MU_PARSEOPT_VERSION_HOOK;
 	  pohint.po_version_hook =
 	    va_arg (ap, void (*) (struct mu_parseopt *, mu_stream_t));
+          if (pohint.po_version_hook)
+	    pohint.po_flags |= MU_PARSEOPT_VERSION_HOOK;
 	  break;
 	  
 	case MU_CLI_OPTION_PROG_DOC_HOOK:
-	  pohint.po_flags |= MU_PARSEOPT_PROG_DOC_HOOK;
 	  pohint.po_prog_doc_hook =
 	    va_arg (ap, void (*) (struct mu_parseopt *, mu_stream_t));
+          if (pohint.po_prog_doc_hook)
+	    pohint.po_flags |= MU_PARSEOPT_PROG_DOC_HOOK;
 	  break;
 	  
 	case MU_CLI_OPTION_NEGATION:
-	  pohint.po_flags |= MU_PARSEOPT_NEGATION;
 	  pohint.po_negation = va_arg (ap, char *);
+	  if (pohint.po_negation)
+	    pohint.po_flags |= MU_PARSEOPT_NEGATION;
 	  break;
 	  
 	case MU_CLI_OPTION_SPECIAL_ARGS:
-	  pohint.po_flags |= MU_PARSEOPT_SPECIAL_ARGS;
 	  pohint.po_special_args = va_arg (ap, char *);
+          if (pohint.po_special_args)
+	    pohint.po_flags |= MU_PARSEOPT_SPECIAL_ARGS;
 	  break;
 
 	case MU_CLI_OPTION_CONF_SITE_FILE:
@@ -198,6 +209,11 @@ mu_cli_simple (int argc, char **argv, ...)
 	  cfhint.flags |= MU_CFHINT_NO_CONFIG_OVERRIDE;
 	  break;
 
+	case MU_CLI_OPTION_CONF_PROGNAME:
+	  if ((cfhint.program = va_arg (ap, char *)) != NULL)
+	    cfhint.flags |= MU_CFHINT_PROGRAM;
+	  break;
+
 	default:
 	  mu_diag_output (MU_DIAG_CRIT,
 			  _("%s:%d: INTERNAL ERROR: unrecognized mu_cli_simple option"),
diff --git a/mu/libexec/Makefile.am b/mu/libexec/Makefile.am
index e94ebccc9..03bbb318d 100644
--- a/mu/libexec/Makefile.am
+++ b/mu/libexec/Makefile.am
@@ -83,6 +83,16 @@ if MU_COND_SUPPORT_IMAP
  $(MUTOOL_LIBRARIES_TAIL)
 endif
 
+if MU_COND_SUPPORT_MAILDIR
+ pkglibexec_PROGRAMS += mailutils-maildir_fixup
+ mailutils_maildir_fixup_SOURCES = maildir_fixup.c
+ mailutils_maildir_fixup_LDADD = \
+  $(MU_APP_LIBRARIES)\
+  $(MU_LIB_MAILDIR)\
+  $(MU_LIB_MAILUTILS)\
+  $(MUTOOL_LIBRARIES_TAIL)
+endif
+
 mailutils_send_SOURCES = send.c
 mailutils_send_CPPFLAGS = \
  $(AM_CPPFLAGS)\
diff --git a/mu/libexec/maildir_fixup.c b/mu/libexec/maildir_fixup.c
new file mode 100644
index 000000000..811380691
--- /dev/null
+++ b/mu/libexec/maildir_fixup.c
@@ -0,0 +1,202 @@
+/* GNU Mailutils -- a suite of utilities for electronic mail
+   Copyright (C) 2010-2020 Free Software Foundation, Inc.
+
+   GNU Mailutils 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 3, or (at your option)
+   any later version.
+
+   GNU Mailutils 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 GNU Mailutils.  If not, see <http://www.gnu.org/licenses/>. */
+
+#if defined(HAVE_CONFIG_H)
+# include <config.h>
+#endif
+#include <mailutils/mailutils.h>
+#include <sysexits.h>
+#include "mu.h"
+#include "muaux.h"
+
+/* Utility-specific exit codes */
+enum
+  {
+    EXIT_OK,        /* Success */
+    EXIT_HARDFAIL,  /* None of the maildirs fixed */
+    EXIT_SOFTFAIL,  /* Some of the maildirs failed to fix */ 
+  };
+
+static int verbose_option;
+static int dry_run_option;
+static unsigned long fail_count;
+static unsigned long succ_count;
+
+static struct mu_option options[] = 
+{
+  { "verbose", 'v', NULL, MU_OPTION_DEFAULT,
+    "verbosely list what is being done",
+    mu_c_incr, &verbose_option },
+  { "dry-run", 'n', NULL, MU_OPTION_DEFAULT,
+    "do nothing, print everything",
+    mu_c_incr, &dry_run_option },  
+    MU_OPTION_END
+};
+
+static int
+mailbox_fixup (void *item, void *data)
+{
+  struct mu_list_response *resp = item;
+  mu_mailbox_t mbox = NULL;
+  int rc;
+
+  if (!(resp->type & MU_FOLDER_ATTRIBUTE_FILE))
+    return 0;
+  
+  if (verbose_option)
+    mu_diag_output (MU_DIAG_INFO, "Fixing %s", resp->name);
+  if (dry_run_option)
+    return 0;
+  
+  rc = manlock_open_mailbox (&mbox, resp->name, 1, MU_STREAM_RDWR);
+  if (rc == 0)
+    {
+      rc = mu_mailbox_scan (mbox, 1, NULL);
+      mu_mailbox_close (mbox);
+      manlock_unlock (mbox);
+      mu_mailbox_destroy (&mbox);
+    }
+  else
+    mu_error ("can't open mailbox: %s", mu_strerror (rc));
+  
+  if (rc)
+    fail_count++;
+  else
+    succ_count++;
+  return rc;
+}
+
+static inline int
+filename_ok (char const *fname)
+{
+  return fname[0] == '/' ||
+         fname[0] == '~' ||
+         (fname[0] == '.' &&
+	  (fname[1] == '/' || (fname[1] == '.' && fname[2] == '/')));
+}
+
+static int
+fix_mailboxes_in_folder (char *fname)
+{
+  mu_folder_t folder;
+  struct mu_folder_scanner scn = MU_FOLDER_SCANNER_INITIALIZER;
+  int rc;
+     
+  if (!filename_ok (fname))
+    {
+      char *cwd = mu_getcwd ();
+      size_t prefix_len = strlen (cwd);
+      if (cwd[prefix_len-1] != '/')
+	prefix_len++;
+      fname = mu_make_file_name (cwd, fname);
+      free (cwd);
+      if (!fname)
+	mu_alloc_die ();
+    }
+  
+  rc = mu_folder_create (&folder, fname);
+  if (rc)
+    {
+      mu_diag_funcall (MU_DIAG_ERROR, "mu_folder_create", fname, rc);
+      return rc;
+    }
+  rc = mu_folder_open (folder, MU_STREAM_READ);
+  if (rc)
+    {
+      mu_diag_funcall (MU_DIAG_ERROR, "mu_folder_open", fname, rc);
+      goto err;
+    }
+
+  rc = mu_list_create (&scn.result);
+  if (rc)
+    {
+      mu_diag_funcall (MU_DIAG_ERROR, "mu_list_create", NULL, rc);
+      goto err;
+    }
+  
+  rc = mu_folder_scan (folder, &scn);
+  if (rc)
+    mu_diag_funcall (MU_DIAG_ERROR, "mu_folder_scan", NULL, rc);
+  else
+    mu_list_foreach (scn.result, mailbox_fixup, NULL);
+  
+ err:
+  mu_list_destroy (&scn.result);
+  mu_folder_destroy (&folder);
+  return rc;
+}
+
+static char docstring[] = N_(
+  "recursively scans all maildirs in the folder\n"
+  "\nThis induces fixing of the maildir message attributes (bug #56428) "
+  "and attaching persistent UID numbers (commits fd9b19bac-d7110faa).\n"
+);
+static char argdoc[] = N_("FOLDER ...");
+static char *capa[] = {
+  "debug",
+  "locking",
+  NULL
+};
+
+static struct mu_cfg_param config_param[] = {
+  { "mandatory-locking", mu_cfg_section },
+  { NULL }
+};
+
+int
+main (int argc, char **argv)
+{
+  int i;
+
+  mu_registrar_record (mu_maildir_record);
+  mu_registrar_set_default_scheme ("maildir");
+  manlock_cfg_init ();
+  mu_cli_simple (argc, argv,
+		 MU_CLI_OPTION_OPTIONS, options,
+		 MU_CLI_OPTION_OPTIONS, common_options,
+		 MU_CLI_OPTION_PROG_NAME, getenv ("MAILUTILS_PROGNAME"),
+		 MU_CLI_OPTION_PROG_DOC, docstring,
+		 MU_CLI_OPTION_PROG_ARGS, argdoc,
+		 MU_CLI_OPTION_RETURN_ARGC, &argc,
+                 MU_CLI_OPTION_RETURN_ARGV, &argv,
+		 MU_CLI_OPTION_PACKAGE_NAME, PACKAGE_NAME,   
+		 MU_CLI_OPTION_PACKAGE_URL, PACKAGE_URL,   
+		 MU_CLI_OPTION_BUG_ADDRESS, PACKAGE_BUGREPORT,   
+		 MU_CLI_OPTION_VERSION_HOOK, mu_version_hook,
+		 MU_CLI_OPTION_CAPABILITIES, capa,
+		 MU_CLI_OPTION_CONFIG, config_param,
+		 MU_CLI_OPTION_CONF_SITE_FILE, NULL,
+		 MU_CLI_OPTION_CONF_PROGNAME, "maildir_fixup",
+		 MU_CLI_OPTION_END);
+                 
+  if (argc == 0)
+    {
+      mu_error ("required argument missing; try --help for more info");
+      exit (EX_USAGE);
+    }
+  
+  if (dry_run_option)
+    verbose_option++;
+  
+  for (i = 0; i < argc; i++)
+    fix_mailboxes_in_folder (argv[i]);
+
+  if (fail_count)
+    exit (succ_count == 0 ? EXIT_HARDFAIL : EXIT_SOFTFAIL);
+  
+  exit (EXIT_OK); 
+}
+
diff --git a/mu/libexec/mu.h b/mu/libexec/mu.h
index 7631728f3..8050ce3e0 100644
--- a/mu/libexec/mu.h
+++ b/mu/libexec/mu.h
@@ -21,6 +21,7 @@
 #include <stdarg.h>
 #include <mailutils/mailutils.h>
 
+extern struct mu_option common_options[];
 void mu_action_getopt (int *pargc, char ***pargv, struct mu_option *opt,
 		       char const *docstring, char const *argdoc);
 int mu_vgetans (const char *variants, const char *fmt, va_list ap);