Send multipart/alternative messages using mail.

The new option --alternative is provided to change the content type of
the composed message to multipart/alternative.  The ~/ escape toggles
the type between multipart/mixed and multipart/alternative.  In messages
of multipart/alternative type, the Content-Disposition header of all
attachments is reset to "inline".

* libmailutils/mime/mime.c (mu_mime_create): Bugfix: honour the
MU_MIME_MULTIPART_ALT flag.
* mail/mail.c: New option --alternative.
* mail/mail.h (compose_env) <attlist,mime>: New members.
(multipart_alternative): New global.
(send_attach_file): Change return value.
(escape_toggle_multipart_type): New proto.
* mail/send.c (multipart_alternative): New global.
Keep the list of attachments in compose_env_t.  Make sure it is freed
when no longer used.
Implement the ~/ escape.
* mail/table.c: New escape ~/
* mail/util.c: Use mu_strerror instead of strerror.

* NEWS: Document changes to the mail utility
* doc/texinfo/programs.texi: Likewise.

-GNU mailutils NEWS -- history of user-visible changes. 2017-04-09
+GNU mailutils NEWS -- history of user-visible changes. 2017-04-13
 Copyright (C) 2002-2017 Free Software Foundation, Inc.
 See the end of file for copying conditions.
 
@@ -88,6 +88,21 @@ defined.  Instead, the following constants are defined in config.h:
 
 * movemail: new option --progress-meter
 
+* mail: sending multipart messages
+
+** New option --alternative
+
+When used with --attach or --attach-fd options, this option sets the
+Content-Type of the constructed message to "multipart/alternative".
+In the absense of this option, the type is "multipart/mixed".
+
+** New escape ~/
+
+New escape ~/ toggles the Content-Type of the message being composed
+between "multipart/mixed" and "multipart/alternative".
+
+The actual Content-Type is displayed by the ~l (list attachments) escape.
+
 * scheme implementation of the Sieve language discontinued
 
 There's no reason to keep two different implementations of the Sieve

@@ -3420,12 +3420,19 @@ To list the files attached so far, use the @samp{~l} escape:
 
 @example
 ~l
+multipart/mixed
    1 myfile.html text/html base64
 @end example
 
-Each line of the listing contains the ordinal number of the attachment,
+The first line of the output shows the content type of the message.
+Each subsequent line contains the ordinal number of the attachment,
 the name of the file, content-type and transfer encoding used.
 
+@cindex ~/, mail escape
+The @samp{~/} escape toggles the content type bewteen
+@samp{multipart/mixed}, and @samp{multipart/alternative}.  The new
+value of the content type is displayed on the screen.
+
 @cindex ~^, mail escape
 The @samp{~^} escape removes attachments.  Its argument is the number
 of the attachment to remove, e.g.:
@@ -3568,6 +3575,12 @@ either or both of them using the @option{--content-name} and
 affect only the next @option{--attach} (or @option{--attach-fd}, see
 below) option.
 
+By default, the message will be assigned the content type
+@samp{multipart/mixed}.  To change it to @samp{multipart/alternative},
+use the @option{--alternative} command line option.  Using this option
+also sets the @samp{Content-Disposition} header of each attached
+message to @samp{inline}.
+
 All the examples above will enter the usual interactive shell,
 allowing you to compose the body of the message.  If that's not
 needed, the non-interactive use can be forced by redirecting

@@ -879,6 +879,9 @@ _mime_body_lines (mu_body_t body, size_t *plines)
   return 0;
 }
 
+#define MIME_MULTIPART_FLAGS \
+  (MU_MIME_MULTIPART_MIXED|MU_MIME_MULTIPART_ALT)
+
 int
 mu_mime_create (mu_mime_t *pmime, mu_message_t msg, int flags)
 {
@@ -889,6 +892,16 @@ mu_mime_create (mu_mime_t *pmime, mu_message_t msg, int flags)
   
   if (pmime == NULL)
     return EINVAL;
+  
+  switch (flags & MIME_MULTIPART_FLAGS)
+    {
+    case MIME_MULTIPART_FLAGS:
+      return EINVAL;
+
+    case 0:
+      flags |= MU_MIME_MULTIPART_MIXED;
+    }
+  
   *pmime = NULL;
   if ((mime = calloc (1, sizeof (*mime))) == NULL)
     return ENOMEM;
@@ -931,7 +944,7 @@ mu_mime_create (mu_mime_t *pmime, mu_message_t msg, int flags)
     }
   else
     {
-      mime->flags |= MIME_NEW_MESSAGE | MU_MIME_MULTIPART_MIXED;
+      mime->flags |= MIME_NEW_MESSAGE;
     }
   if (ret != 0)
     {

@@ -146,9 +146,8 @@ cli_attach (struct mu_parseopt *po, struct mu_option *opt, char const *arg)
       arg = NULL;
       fd = 0;
     }
-  if (send_attach_file (fd, arg, content_filename, content_name,
-			default_content_type, default_encoding))
-    exit (1);
+  send_attach_file (fd, arg, content_filename, content_name,
+		    default_content_type, default_encoding);
 
   free (content_name);
   content_name = NULL;
@@ -169,9 +168,8 @@ cli_attach_fd (struct mu_parseopt *po, struct mu_option *opt, char const *arg)
       exit (po->po_exit_error);
     }
   
-  if (send_attach_file (fd, NULL, content_filename, content_name,
-			default_content_type, default_encoding))
-    exit (1);
+  send_attach_file (fd, NULL, content_filename, content_name,
+		    default_content_type, default_encoding);
 
   free (content_name);
   content_name = NULL;
@@ -240,6 +238,10 @@ static struct mu_option mail_options[] = {
     N_("append given header to the message being sent"),
     mu_c_string, NULL, cli_append },
 
+  { "alternative", 0, NULL, MU_OPTION_DEFAULT,
+    N_("force multipart/alternative content type"),
+    mu_c_bool, &multipart_alternative },
+    
   { "skip-empty-attachments", 0, NULL, MU_OPTION_DEFAULT,
     N_("skip attachments with empty body"),
     mu_c_bool, &skip_empty_attachments },

@@ -103,6 +103,9 @@ typedef struct compose_env
   char **outfiles;      /* Names of the output files. The message is to be
 		           saved in each of these. */
   int nfiles;           /* Number of output files */
+  int alt;              /* Use multipart/alternative type */
+  mu_list_t attlist;    /* Attachments */
+  mu_mime_t mime;       /* Associated MIME object */
 } compose_env_t;
 
 #define MAIL_COMMAND_COMMON_MEMBERS \
@@ -174,6 +177,7 @@ extern const char *program_version;
 extern char *default_encoding;
 extern char *default_content_type;
 extern int skip_empty_attachments;
+extern int multipart_alternative;
 
 /* Functions */
 extern int mail_alias (int argc, char **argv);
@@ -259,7 +263,7 @@ extern char *mail_expand_name (const char *name);
 
 extern void send_append_header (char const *text);
 extern void send_append_header2 (char const *name, char const *value, int mode);
-extern int send_attach_file (int fd,
+extern void send_attach_file (int fd,
 			      const char *filename,
 			      const char *content_filename,
 			      const char *content_name,
@@ -292,6 +296,8 @@ extern int escape_list_attachments  (int argc, char **argv,
 extern int escape_attach (int argc, char **argv, compose_env_t *env);
 extern int escape_remove_attachment (int argc, char **argv,
 				     compose_env_t *env);
+extern int escape_toggle_multipart_type (int argc, char **argv,
+					 compose_env_t *env);
 
 enum
   {

@@ -24,6 +24,8 @@
 static int isfilename (const char *);
 static int msg_to_pipe (const char *cmd, mu_message_t msg);
 
+int multipart_alternative;
+
 
 /* Additional message headers */
 struct add_header
@@ -143,8 +145,6 @@ struct atchinfo
   int skip_empty;
 };
 
-static mu_list_t attlist;
-
 static void
 atchinfo_free (void *p)
 {
@@ -158,18 +158,62 @@ atchinfo_free (void *p)
   free (ap);
 }
 
+static mu_list_t
+attlist_new (void)
+{
+  mu_list_t lst;
+  int rc = mu_list_create (&lst);
+  if (rc)
+    {
+      mu_diag_funcall (MU_DIAG_ERROR, "mu_list_create", NULL, rc);
+      exit (1);
+    }
+  mu_list_set_destroy_item (lst, atchinfo_free);
+  return lst;
+}
+
+static void
+attlist_add (mu_list_t attlist, char *id, char const *encoding,
+	     char const *content_type, char const *content_name,
+	     char const *content_filename,
+	     mu_stream_t stream, int skip_empty)
+{
+  struct atchinfo *aptr;
+  int rc;
+  
+  aptr = mu_alloc (sizeof (*aptr));
+
+  aptr->id = id ? mu_strdup (id) : id;
+  aptr->encoding = mu_strdup (encoding);  
+  aptr->content_type = mu_strdup (content_type ?
+				  content_type : "application/octet-stream");
+  aptr->name = content_name ? mu_strdup (content_name) : NULL;
+  aptr->filename = content_filename ? mu_strdup (content_filename) : NULL;
+  aptr->source = stream;
+  if (stream)
+    mu_stream_ref (stream);
+  aptr->skip_empty = skip_empty;
+  rc = mu_list_append (attlist, aptr);
+  if (rc)
+    {
+      mu_diag_funcall (MU_DIAG_ERROR, "mu_list_append", NULL, rc);
+      exit (1);
+    }
+}
+
 int
-send_attach_file (int fd,
+attlist_attach_file (mu_list_t *attlist_ptr,
+		     int fd,
 		     const char *realname,
 		     const char *content_filename, const char *content_name,
 		     const char *content_type, const char *encoding)
 {
   int rc;
   struct stat st;
-  struct atchinfo *aptr;
   mu_list_t list;
   mu_stream_t stream = NULL;
   char *id = NULL;
+  mu_list_t attlist;
   
   if (fd >= 0)
     {
@@ -238,32 +282,75 @@ send_attach_file (int fd,
       return 1;
     }
   
-  if (!attlist)
-    {
-      rc = mu_list_create (&attlist);
-      if (rc)
+  if (!*attlist_ptr)
     {
-	  mu_diag_funcall (MU_DIAG_ERROR, "mu_list_create", NULL, rc);
-	  exit (1);
-	}
-      mu_list_set_destroy_item (attlist, atchinfo_free);
+      attlist = attlist_new ();
+      *attlist_ptr = attlist;
     }
-  aptr = mu_alloc (sizeof (*aptr));
+  else
+    attlist = *attlist_ptr;
     
-  aptr->id = id;
-  aptr->encoding = mu_strdup (encoding);  
-  aptr->content_type = mu_strdup (content_type ?
-				  content_type : "application/octet-stream");
-  aptr->name = content_name ? mu_strdup (content_name) : NULL;
-  aptr->filename = content_filename ? mu_strdup (content_filename) : NULL;
-  aptr->source = stream;
-  aptr->skip_empty = skip_empty_attachments;
-  rc = mu_list_append (attlist, aptr);
-  if (rc)
-    {
-      mu_diag_funcall (MU_DIAG_ERROR, "mu_list_append", NULL, rc);
-      exit (1);
-    }
+  attlist_add (attlist, id, encoding, content_type,
+	       content_name, content_filename,
+	       stream, skip_empty_attachments);
+  if (stream)
+    mu_stream_unref (stream);
+  free (id);
+
+  return 0;
+}
+
+static int
+attlist_helper (void *item, void *data)
+{
+  struct atchinfo *aptr = item;
+  mu_list_t list = data;
+  attlist_add (list, aptr->id, aptr->encoding, aptr->content_type,
+	       aptr->name, aptr->filename, aptr->source, aptr->skip_empty);
+  return 0;
+}
+
+static mu_list_t
+attlist_copy (mu_list_t src)
+{
+  mu_list_t dst;
+
+  if (!src)
+    return NULL;
+  dst = attlist_new ();
+  mu_list_foreach (src, attlist_helper, dst);
+  return dst;
+}
+
+static mu_list_t attachment_list;
+
+void
+send_attach_file (int fd,
+		  const char *realname,
+		  const char *content_filename, const char *content_name,
+		  const char *content_type, const char *encoding)
+{
+  attlist_attach_file (&attachment_list,
+		       fd,
+		       realname,
+		       content_filename,
+		       content_name,
+		       content_type,
+		       encoding);
+}
+
+static void
+report_multipart_type (compose_env_t *env)
+{
+  mu_printf ("multipart/%s\n", env->alt ? "alternative" : "mixed");
+}
+
+/* ~/ - toggle between multipart/mixed and multipart/alternative */
+int
+escape_toggle_multipart_type (int argc, char **argv, compose_env_t *env)
+{
+  env->alt = !env->alt;
+  report_multipart_type (env);
   return 0;
 }
 
@@ -273,8 +360,10 @@ escape_list_attachments (int argc, char **argv, compose_env_t *env)
   mu_iterator_t itr;
   int i;
   
-  if (mu_list_is_empty (attlist) ||
-      mu_list_get_iterator (attlist, &itr))
+  report_multipart_type (env);
+
+  if (mu_list_is_empty (env->attlist) ||
+      mu_list_get_iterator (env->attlist, &itr))
     {
       mu_printf ("%s\n", _("No attachments"));
       return 0;
@@ -308,7 +397,8 @@ escape_attach (int argc, char **argv, compose_env_t *env)
     case 3:
       content_type = argv[2];
     case 2:
-      return send_attach_file (-1, argv[1], argv[1], argv[1],
+      return attlist_attach_file (&env->attlist,
+				  -1, argv[1], argv[1], argv[1],
 				  content_type, encoding);
     default:
       return escape_check_args (argc, argv, 2, 4);
@@ -332,21 +422,21 @@ escape_remove_attachment (int argc, char **argv, compose_env_t *env)
       return 1;
     }
   
-  mu_list_count (attlist, &count);
+  mu_list_count (env->attlist, &count);
   if (n == 0 || n > count)
     {
       mu_error (_("index out of range"));
       return 1;
     }
 
-  return mu_list_remove_nth (attlist, n - 1);
+  return mu_list_remove_nth (env->attlist, n - 1);
 }
 
 static int
 saveatt (void *item, void *data)
 {
   struct atchinfo *aptr = item;
-  mu_mime_t mime = data;
+  compose_env_t *env = data;
   mu_message_t part;
   mu_header_t hdr;
   int rc;
@@ -390,13 +480,15 @@ saveatt (void *item, void *data)
 	return 0;
     }
       
-  mu_mime_get_num_parts	(mime, &nparts);
+  mu_mime_get_num_parts	(env->mime, &nparts);
   mu_message_get_header (part, &hdr);
+  if (env->alt)
+    mu_header_set_value (hdr, MU_HEADER_CONTENT_DISPOSITION, "inline", 1);
   mu_rfc2822_msg_id (nparts, &p);
   mu_header_set_value (hdr, MU_HEADER_CONTENT_ID, p, 1);
   free (p);
 
-  rc = mu_mime_add_part (mime, part);
+  rc = mu_mime_add_part (env->mime, part);
   mu_message_unref (part);
   if (rc)
     {
@@ -418,7 +510,7 @@ add_body (mu_message_t inmsg, mu_iterator_t itr, mu_mime_t mime)
   int rc;
   
   mu_message_get_body (inmsg, &body);
-  if (skip_empty_attachments)
+  if (skip_empty_attachments || multipart_alternative)
     {
       size_t size;
       rc = mu_body_size (body, &size);
@@ -483,7 +575,7 @@ add_body (mu_message_t inmsg, mu_iterator_t itr, mu_mime_t mime)
 }  
 
 static int
-add_attachments (mu_message_t *pmsg, mu_mime_t *pmime)
+add_attachments (compose_env_t *env, mu_message_t *pmsg)
 {
   mu_message_t inmsg, outmsg;
   mu_header_t inhdr, outhdr;
@@ -491,16 +583,15 @@ add_attachments (mu_message_t *pmsg, mu_mime_t *pmime)
   mu_mime_t mime;  
   int rc;
   
-  if (mu_list_is_empty (attlist))
-    {
-      *pmime = NULL;
+  if (mu_list_is_empty (env->attlist))
     return 0;
-    }
   
   inmsg = *pmsg;
 
   /* Create a mime object */
-  rc = mu_mime_create (&mime, NULL, 0);
+  rc = mu_mime_create (&mime, NULL,
+		       env->alt ?
+		         MU_MIME_MULTIPART_ALT : MU_MIME_MULTIPART_MIXED);
   if (rc)
     {
       mu_diag_funcall (MU_DIAG_ERROR, "mu_mime_create", NULL, rc);
@@ -517,8 +608,10 @@ add_attachments (mu_message_t *pmsg, mu_mime_t *pmime)
       return 1;
     }
 
+  env->mime = mime;
+
   /* Add the respective attachments */
-  rc = mu_list_foreach (attlist, saveatt, mime);
+  rc = mu_list_foreach (env->attlist, saveatt, env);
   if (rc)
     {
       mu_mime_destroy (&mime);
@@ -559,7 +652,6 @@ add_attachments (mu_message_t *pmsg, mu_mime_t *pmime)
   mu_message_unref (inmsg);
 
   *pmsg = outmsg;
-  *pmime = mime;
   return 0;
 }
 
@@ -785,6 +877,8 @@ void
 compose_init (compose_env_t *env)
 {
   memset (env, 0, sizeof (*env));
+  env->alt = multipart_alternative;
+  env->attlist = attlist_copy (attachment_list);
   mu_list_foreach (add_header_list, seed_headers, env);
 }
 
@@ -873,6 +967,9 @@ compose_destroy (compose_env_t *env)
 {
   mu_header_destroy (&env->header);
   free (env->outfiles);
+  mu_mime_destroy (&env->mime);
+  mu_list_destroy (&env->attlist);
+  mu_stream_destroy (&env->compstr);
 }
 
 static int
@@ -1112,7 +1209,6 @@ mail_send0 (compose_env_t *env, int save_to)
   if (rc)
     {
       mu_error (_("Cannot open temporary file: %s"), mu_strerror (rc));
-      mu_list_destroy (&attlist);
       return 1;
     }
 
@@ -1208,8 +1304,6 @@ mail_send0 (compose_env_t *env, int save_to)
   if (int_cnt)
     {
       save_dead_message_env (env);
-      mu_stream_destroy (&env->compstr);
-      mu_list_destroy (&attlist);
       return 1;
     }
 
@@ -1225,7 +1319,6 @@ mail_send0 (compose_env_t *env, int save_to)
 
   if (util_header_expand (&env->header) == 0)
     {
-      mu_mime_t mime = NULL;
       mu_message_t msg = NULL;
       int status = 0;
       int sendit = (compose_header_get (env, MU_HEADER_TO, NULL) ||
@@ -1246,7 +1339,7 @@ mail_send0 (compose_env_t *env, int save_to)
 	  mu_message_set_header (msg, env->header, NULL);
 	  env->header = NULL;
 	  
-	  status = add_attachments (&msg, &mime);
+	  status = add_attachments (env, &msg);
 	  if (status)
 	    break;
 	  
@@ -1323,14 +1416,10 @@ mail_send0 (compose_env_t *env, int save_to)
 
       mu_stream_destroy (&env->compstr);
       mu_message_destroy (&msg, NULL);
-      mu_mime_destroy (&mime);
       return status;
     }
   else
     save_dead_message_env (env);
-  
-  mu_stream_destroy (&env->compstr);
-  mu_list_destroy (&attlist);
   return 1;
 }
 

@@ -228,6 +228,7 @@ static const struct mail_escape_entry mail_escape_table[] = {
   {"-",	"-",	"-[mail-command]",  escape_command },
   {"+",	"+",	"+name [content-type [encoding]]", escape_attach },
   {"^",	"^",	"^N",               escape_remove_attachment },
+  {"/", "/",    "/",                escape_toggle_multipart_type },
   {"?",	"?",	"?",		    escape_help },
   {"A",	"A",	"A",		    escape_sign },
   {"a",	"a",	"a",		    escape_sign },

@@ -706,7 +706,7 @@ util_save_outgoing (mu_message_t msg, char *savefile)
       if (rc)
 	{
 	  mu_error (_("Cannot create output mailbox `%s': %s"),
-		      filename, strerror (rc));
+		      filename, mu_strerror (rc));
 	  free (filename);
 	  return;
 	}
@@ -714,13 +714,13 @@ util_save_outgoing (mu_message_t msg, char *savefile)
       rc = mu_mailbox_open (outbox, MU_STREAM_WRITE | MU_STREAM_CREAT);
       if (rc)
 	mu_error (_("Cannot open output mailbox `%s': %s"),
-		    filename, strerror (rc));
+		    filename, mu_strerror (rc));
       else
 	{
 	  rc = mu_mailbox_append_message (outbox, msg);
 	  if (rc)
 	    mu_error (_("Cannot append message to `%s': %s"),
-			filename, strerror (rc));
+			filename, mu_strerror (rc));
 	}
 
       mu_mailbox_close (outbox);