[PATCH 4/4] show: Rewrite show_message_body to use the MIME tree interface.

[Austin Clements <amdragon@MIT.EDU>]

This removes all of the MIME traversal logic from show_message_body
and leaves only its interaction with the format callbacks.

Besides isolating concerns, since traversal happens behind a trivial
interface, there is now much less code duplication in
show_message_part.  Also, this uses mime_node_seek_dfs to start at the
requested part, eliminating all of the logic about parts being
selected or being in_zone (and reducing the "show state" to only a
part counter).  notmuch_show_params_t no longer needs to be passed
through the recursion because the only two fields that mattered
(related to crypto) are now handled by the MIME tree.

The few remaining complexities in show_message_part highlight
irregularities in the format callbacks with respect to top-level
messages and embedded message parts.

Since this is a rewrite, the diff is not very enlightening.  It's
easier to look at the old code and the new code side-by-side.
---
 show-message.c |  329 +++++++++++++++++--------------------------------------
 1 files changed, 102 insertions(+), 227 deletions(-)
 rewrite show-message.c (81%)

diff --git a/show-message.c b/show-message.c
dissimilarity index 81%
index 09fa607..4560aea 100644
--- a/show-message.c
+++ b/show-message.c
@@ -1,227 +1,102 @@
-/* notmuch - Not much of an email program, (just index and search)
- *
- * Copyright © 2009 Carl Worth
- * Copyright © 2009 Keith Packard
- *
- * This program 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 of the License, or
- * (at your option) any later version.
- *
- * This program 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 http://www.gnu.org/licenses/ .
- *
- * Authors: Carl Worth <cworth@cworth.org>
- *	    Keith Packard <keithp@keithp.com>
- */
-
-#include "notmuch-client.h"
-
-typedef struct show_message_state {
-    int part_count;
-    int in_zone;
-} show_message_state_t;
-
-static void
-show_message_part (GMimeObject *part,
-		   show_message_state_t *state,
-		   const notmuch_show_format_t *format,
-		   notmuch_show_params_t *params,
-		   int first)
-{
-    GMimeObject *decryptedpart = NULL;
-    int selected;
-    state->part_count += 1;
-
-    if (! (GMIME_IS_PART (part) || GMIME_IS_MULTIPART (part) || GMIME_IS_MESSAGE_PART (part))) {
-	fprintf (stderr, "Warning: Not displaying unknown mime part: %s.\n",
-		 g_type_name (G_OBJECT_TYPE (part)));
-	return;
-    }
-
-    selected = (params->part <= 0 || state->part_count == params->part);
-
-    if (selected || state->in_zone) {
-	if (!first && (params->part <= 0 || state->in_zone))
-	    fputs (format->part_sep, stdout);
-
-	if (format->part_start)
-	    format->part_start (part, &(state->part_count));
-    }
-
-    /* handle PGP/MIME parts */
-    if (GMIME_IS_MULTIPART (part) && params->cryptoctx) {
-	GMimeMultipart *multipart = GMIME_MULTIPART (part);
-	GError* err = NULL;
-
-	if (GMIME_IS_MULTIPART_ENCRYPTED (part) && params->decrypt)
-	{
-	    if ( g_mime_multipart_get_count (multipart) != 2 ) {
-		/* this violates RFC 3156 section 4, so we won't bother with it. */
-		fprintf (stderr,
-			 "Error: %d part(s) for a multipart/encrypted message (should be exactly 2)\n",
-			 g_mime_multipart_get_count (multipart));
-	    } else {
-		GMimeMultipartEncrypted *encrypteddata = GMIME_MULTIPART_ENCRYPTED (part);
-		decryptedpart = g_mime_multipart_encrypted_decrypt (encrypteddata, params->cryptoctx, &err);
-		if (decryptedpart) {
-		    if ((selected || state->in_zone) && format->part_encstatus)
-			format->part_encstatus (1);
-		    const GMimeSignatureValidity *sigvalidity = g_mime_multipart_encrypted_get_signature_validity (encrypteddata);
-		    if (!sigvalidity)
-			fprintf (stderr, "Failed to verify signed part: %s\n", (err ? err->message : "no error explanation given"));
-		    if ((selected || state->in_zone) && format->part_sigstatus)
-			format->part_sigstatus (sigvalidity);
-		} else {
-		    fprintf (stderr, "Failed to decrypt part: %s\n", (err ? err->message : "no error explanation given"));
-		    if ((selected || state->in_zone) && format->part_encstatus)
-			format->part_encstatus (0);
-		}
-	    }
-	}
-	else if (GMIME_IS_MULTIPART_SIGNED (part))
-	{
-	    if ( g_mime_multipart_get_count (multipart) != 2 ) {
-		/* this violates RFC 3156 section 5, so we won't bother with it. */
-		fprintf (stderr,
-			 "Error: %d part(s) for a multipart/signed message (should be exactly 2)\n",
-			 g_mime_multipart_get_count (multipart));
-	    } else {
-		/* For some reason the GMimeSignatureValidity returned
-		 * here is not a const (inconsistent with that
-		 * returned by
-		 * g_mime_multipart_encrypted_get_signature_validity,
-		 * and therefore needs to be properly disposed of.
-		 * Hopefully the API will become more consistent. */
-		GMimeSignatureValidity *sigvalidity = g_mime_multipart_signed_verify (GMIME_MULTIPART_SIGNED (part), params->cryptoctx, &err);
-		if (!sigvalidity) {
-		    fprintf (stderr, "Failed to verify signed part: %s\n", (err ? err->message : "no error explanation given"));
-		}
-		if ((selected || state->in_zone) && format->part_sigstatus)
-		    format->part_sigstatus (sigvalidity);
-		if (sigvalidity)
-		    g_mime_signature_validity_free (sigvalidity);
-	    }
-	}
-
-	if (err)
-	    g_error_free (err);
-    }
-    /* end handle PGP/MIME parts */
-
-    if (selected || state->in_zone)
-	format->part_content (part);
-
-    if (GMIME_IS_MULTIPART (part)) {
-	GMimeMultipart *multipart = GMIME_MULTIPART (part);
-	int i;
-
-	if (selected)
-	    state->in_zone = 1;
-
-	if (decryptedpart) {
-	    /* We emit the useless application/pgp-encrypted version
-	     * part here only to keep the emitted output as consistent
-	     * as possible between decrypted output and the
-	     * unprocessed multipart/mime. For some strange reason,
-	     * the actual encrypted data is the second part of the
-	     * multipart. */
-	    show_message_part (g_mime_multipart_get_part (multipart, 0), state, format, params, TRUE);
-	    show_message_part (decryptedpart, state, format, params, FALSE);
-	} else {
-	    for (i = 0; i < g_mime_multipart_get_count (multipart); i++) {
-		show_message_part (g_mime_multipart_get_part (multipart, i),
-				   state, format, params, i == 0);
-	    }
-	}
-
-	if (selected)
-	    state->in_zone = 0;
-
-    } else if (GMIME_IS_MESSAGE_PART (part)) {
-	GMimeMessage *mime_message = g_mime_message_part_get_message (GMIME_MESSAGE_PART (part));
-
-	if (selected)
-	    state->in_zone = 1;
-
-	if (selected || (!selected && state->in_zone)) {
-	    fputs (format->header_start, stdout);
-	    if (format->header_message_part)
-		format->header_message_part (mime_message);
-	    fputs (format->header_end, stdout);
-
-	    fputs (format->body_start, stdout);
-	}
-
-	show_message_part (g_mime_message_get_mime_part (mime_message),
-			   state, format, params, TRUE);
-
-	if (selected || (!selected && state->in_zone))
-	    fputs (format->body_end, stdout);
-
-	if (selected)
-	    state->in_zone = 0;
-    }
-
-    if (selected || state->in_zone) {
-	if (format->part_end)
-	    format->part_end (part);
-    }
-}
-
-notmuch_status_t
-show_message_body (notmuch_message_t *message,
-		   const notmuch_show_format_t *format,
-		   notmuch_show_params_t *params)
-{
-    GMimeStream *stream = NULL;
-    GMimeParser *parser = NULL;
-    GMimeMessage *mime_message = NULL;
-    notmuch_status_t ret = NOTMUCH_STATUS_SUCCESS;
-    const char *filename = notmuch_message_get_filename (message);
-    FILE *file = NULL;
-    show_message_state_t state;
-
-    state.part_count = 0;
-    state.in_zone = 0;
-
-    file = fopen (filename, "r");
-    if (! file) {
-	fprintf (stderr, "Error opening %s: %s\n", filename, strerror (errno));
-	ret = NOTMUCH_STATUS_FILE_ERROR;
-	goto DONE;
-    }
-
-    stream = g_mime_stream_file_new (file);
-    g_mime_stream_file_set_owner (GMIME_STREAM_FILE (stream), FALSE);
-
-    parser = g_mime_parser_new_with_stream (stream);
-
-    mime_message = g_mime_parser_construct_message (parser);
-
-    show_message_part (g_mime_message_get_mime_part (mime_message),
-		       &state,
-		       format,
-		       params,
-		       TRUE);
-
-  DONE:
-    if (mime_message)
-	g_object_unref (mime_message);
-
-    if (parser)
-	g_object_unref (parser);
-
-    if (stream)
-	g_object_unref (stream);
-
-    if (file)
-	fclose (file);
-
-    return ret;
-}
+/* notmuch - Not much of an email program, (just index and search)
+ *
+ * Copyright © 2009 Carl Worth
+ * Copyright © 2009 Keith Packard
+ *
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 http://www.gnu.org/licenses/ .
+ *
+ * Authors: Carl Worth <cworth@cworth.org>
+ *	    Keith Packard <keithp@keithp.com>
+ */
+
+#include "notmuch-client.h"
+
+typedef struct show_message_state {
+    int part_count;
+} show_message_state_t;
+
+static void
+show_message_part (mime_node_t *node,
+		   show_message_state_t *state,
+		   const notmuch_show_format_t *format,
+		   int first)
+{
+    /* Formatters expect the envelope for embedded message parts */
+    GMimeObject *part = node->envelope_part ?
+	GMIME_OBJECT (node->envelope_part) : node->part;
+    int i;
+
+    if (!first)
+	fputs (format->part_sep, stdout);
+
+    /* Format this part */
+    if (format->part_start)
+	format->part_start (part, &(state->part_count));
+
+    if (node->is_encrypted && format->part_encstatus)
+	format->part_encstatus (node->decrypt_success);
+
+    if (node->is_signed && format->part_sigstatus)
+	format->part_sigstatus (node->sig_validity);
+
+    format->part_content (part);
+
+    if (node->envelope_part) {
+	fputs (format->header_start, stdout);
+	if (format->header_message_part)
+	    format->header_message_part (GMIME_MESSAGE (node->part));
+	fputs (format->header_end, stdout);
+
+	fputs (format->body_start, stdout);
+    }
+
+    /* Recurse over the children */
+    state->part_count += 1;
+    for (i = 0; i < node->children; i++)
+	show_message_part (mime_node_child (node, i), state, format, i == 0);
+
+    /* Finish this part */
+    if (node->envelope_part)
+	fputs (format->body_end, stdout);
+
+    if (format->part_end)
+	format->part_end (part);
+}
+
+notmuch_status_t
+show_message_body (notmuch_message_t *message,
+		   const notmuch_show_format_t *format,
+		   notmuch_show_params_t *params)
+{
+    notmuch_status_t ret;
+    show_message_state_t state;
+    mime_node_t *root, *part;
+
+    ret = mime_node_open (NULL, message, params->cryptoctx, params->decrypt,
+			  &root);
+    if (ret)
+	return ret;
+
+    /* The caller of show_message_body has already handled the
+     * outermost envelope, so skip it. */
+    state.part_count = MAX (params->part, 1);
+
+    part = mime_node_seek_dfs (root, state.part_count);
+    if (part)
+	show_message_part (part, &state, format, TRUE);
+
+    talloc_free (root);
+
+    return NOTMUCH_STATUS_SUCCESS;
+}
-- 
1.7.5.4