Decode headers in reply

When headers contain non-ASCII characters, they are encoded according
to rfc2047. Nomtuch reply command emits the headers in the encoded
form, which makes them hard to read by humans who compose the reply.

For example instead of "Subject: Re: Rozlučka" one currently sees
"Subject: Re: =?iso-8859-2?q?Rozlu=E8ka?=".

This patch adds a new GMime filter which is used to decode headers to
UTF-8 and uses this filter when notmuch reply outputs headers.

Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz>

1 files changed, 263 insertions, 0 deletions

diff --git a/gmime-filter-headers.c b/gmime-filter-headers.c
new file mode 100644
index 00000000..2f3df801
--- /dev/null
+++ b/gmime-filter-headers.c
@@ -0,0 +1,263 @@
+/*
+ * Copyright © 2009 Keith Packard <keithp@keithp.com>
+ * Copyright © 2010 Michal Sojka <sojkam1@fel.cvut.cz>
+ *
+ * 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, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "gmime-filter-headers.h"
+#include <string.h>
+#include <gmime/gmime-utils.h>
+#include <glib/gprintf.h>
+#include <stdlib.h>
+#include <xutil.h>
+
+/**
+ * SECTION: gmime-filter-headers
+ * @title: GMimeFilterHeaders
+ * @short_description: Add/remove headers markers
+ *
+ * A #GMimeFilter for decoding rfc2047 encoded headers to UTF-8
+ **/
+
+
+static void g_mime_filter_headers_class_init (GMimeFilterHeadersClass *klass);
+static void g_mime_filter_headers_init (GMimeFilterHeaders *filter, GMimeFilterHeadersClass *klass);
+static void g_mime_filter_headers_finalize (GObject *object);
+
+static GMimeFilter *filter_copy (GMimeFilter *filter);
+static void filter_filter (GMimeFilter *filter, char *in, size_t len, size_t prespace,
+			   char **out, size_t *outlen, size_t *outprespace);
+static void filter_complete (GMimeFilter *filter, char *in, size_t len, size_t prespace,
+			     char **out, size_t *outlen, size_t *outprespace);
+static void filter_reset (GMimeFilter *filter);
+
+
+static GMimeFilterClass *parent_class = NULL;
+
+GType
+g_mime_filter_headers_get_type (void)
+{
+	static GType type = 0;
+
+	if (!type) {
+		static const GTypeInfo info = {
+			sizeof (GMimeFilterHeadersClass),
+			NULL, /* base_class_init */
+			NULL, /* base_class_finalize */
+			(GClassInitFunc) g_mime_filter_headers_class_init,
+			NULL, /* class_finalize */
+			NULL, /* class_data */
+			sizeof (GMimeFilterHeaders),
+			0,    /* n_preallocs */
+			(GInstanceInitFunc) g_mime_filter_headers_init,
+			NULL	/* value_table */
+		};
+
+		type = g_type_register_static (GMIME_TYPE_FILTER, "GMimeFilterHeaders", &info, (GTypeFlags) 0);
+	}
+
+	return type;
+}
+
+
+static void
+g_mime_filter_headers_class_init (GMimeFilterHeadersClass *klass)
+{
+	GObjectClass *object_class = G_OBJECT_CLASS (klass);
+	GMimeFilterClass *filter_class = GMIME_FILTER_CLASS (klass);
+
+	parent_class = (GMimeFilterClass *) g_type_class_ref (GMIME_TYPE_FILTER);
+
+	object_class->finalize = g_mime_filter_headers_finalize;
+
+	filter_class->copy = filter_copy;
+	filter_class->filter = filter_filter;
+	filter_class->complete = filter_complete;
+	filter_class->reset = filter_reset;
+}
+
+static void
+g_mime_filter_headers_init (GMimeFilterHeaders *filter, GMimeFilterHeadersClass *klass)
+{
+	(void) klass;
+	filter->saw_nl = TRUE;
+	filter->line = NULL;
+	filter->line_size = 0;
+	filter->lineptr = NULL;
+}
+
+static void
+g_mime_filter_headers_finalize (GObject *object)
+{
+	free (GMIME_FILTER_HEADERS (object)->line);
+	G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+
+static GMimeFilter *
+filter_copy (GMimeFilter *filter)
+{
+	(void) filter;
+	return g_mime_filter_headers_new ();
+}
+
+static void
+output_decoded_header (GMimeFilterHeaders *headers, char **outptr)
+{
+	char *colon, *name, *s, *decoded_value;
+	size_t offset;
+	gint ret;
+
+	colon = strchr (headers->line, ':');
+	if (colon == NULL)
+		return;
+
+	name = headers->line;
+	*colon = '\0';
+	s = colon + 1;
+	while (*s == ' ' || *s == '\t')
+		s++;
+	decoded_value = g_mime_utils_header_decode_text(s);
+	if (decoded_value == NULL)
+		return;
+	offset = *outptr - GMIME_FILTER (headers)->outbuf;
+	g_mime_filter_set_size (GMIME_FILTER (headers), strlen(name) + 2 +
+			       strlen(decoded_value) + 2, TRUE);
+	*outptr = GMIME_FILTER (headers)->outbuf + offset;
+	ret = g_sprintf (*outptr, "%s: %s\n", name, decoded_value);
+	if (ret > 0)
+		*outptr += ret;
+	free (decoded_value);
+}
+
+static void
+output_final_newline (GMimeFilterHeaders *headers, char **outptr)
+{
+	size_t offset;
+
+	offset = *outptr - GMIME_FILTER (headers)->outbuf;
+	g_mime_filter_set_size (GMIME_FILTER (headers), 1, TRUE);
+	*outptr = GMIME_FILTER (headers)->outbuf + offset;
+	*(*outptr)++ = '\n';
+}
+
+static void
+filter_filter (GMimeFilter *filter, char *inbuf, size_t inlen, size_t prespace,
+	       char **outbuf, size_t *outlen, size_t *outprespace)
+{
+	GMimeFilterHeaders *headers = (GMimeFilterHeaders *) filter;
+	register const char *inptr = inbuf;
+	const char *inend = inbuf + inlen;
+	char *lineptr, *lineend, *outptr;
+
+	(void) prespace;
+	if (headers->line == NULL) {
+		headers->line_size = 200;
+		headers->lineptr = headers->line = malloc (headers->line_size);
+	}
+	lineptr = headers->lineptr;
+	lineend = headers->line + headers->line_size;
+	if (lineptr == NULL)
+		return;
+	outptr = filter->outbuf;
+	while (inptr < inend) {
+		if (*inptr == '\n') {
+			if (headers->saw_nl)
+				output_final_newline(headers, &outptr);
+			headers->saw_nl = TRUE;
+			inptr++;
+			continue;
+		}
+
+		if (lineptr == lineend) {
+			headers->line_size *= 2;
+			headers->line = xrealloc (headers->line, headers->line_size);
+			lineptr = headers->line + headers->line_size / 2;
+			lineend = headers->line + headers->line_size;
+		}
+
+		if (headers->saw_nl && *inptr != ' ' && *inptr != '\t') {
+			*lineptr = '\0';
+			output_decoded_header (headers, &outptr);
+			lineptr = headers->line;
+		}
+		if (headers->saw_nl && (*inptr == ' ' || *inptr == '\t')) {
+			*lineptr = ' ';
+			lineptr++;
+			while (inptr < inend && (*inptr == ' ' || *inptr == '\t'))
+				inptr++;
+			headers->saw_nl = FALSE;
+			continue;
+		}
+		headers->saw_nl = FALSE;
+
+		if (*inptr != '\r')
+			*lineptr++ = *inptr;
+		inptr++;
+	}
+	if (headers->saw_nl) {
+		*lineptr = '\0';
+		output_decoded_header (headers, &outptr);
+		lineptr = headers->line;
+	}
+	headers->lineptr = lineptr;
+	*outlen = outptr - filter->outbuf;
+	*outprespace = filter->outpre;
+	*outbuf = filter->outbuf;
+}
+
+static void
+filter_complete (GMimeFilter *filter, char *inbuf, size_t inlen, size_t prespace,
+		 char **outbuf, size_t *outlen, size_t *outprespace)
+{
+	if (inbuf && inlen)
+		filter_filter (filter, inbuf, inlen, prespace, outbuf, outlen, outprespace);
+}
+
+static void
+filter_reset (GMimeFilter *filter)
+{
+	GMimeFilterHeaders *headers = (GMimeFilterHeaders *) filter;
+
+	headers->saw_nl = TRUE;
+	free(headers->line);
+	headers->line = NULL;
+	headers->line_size = 0;
+}
+
+
+/**
+ * g_mime_filter_headers_new:
+ * @encode: %TRUE if the filter should encode or %FALSE otherwise
+ * @dots: encode/decode dots (as for SMTP)
+ *
+ * Creates a new #GMimeFilterHeaders filter.
+ *
+ * If @encode is %TRUE, then all lines will be prefixed by "> ",
+ * otherwise any lines starting with "> " will have that removed
+ *
+ * Returns: a new #GMimeFilterHeaders filter.
+ **/
+GMimeFilter *
+g_mime_filter_headers_new (void)
+{
+	GMimeFilterHeaders *new_headers;
+
+	new_headers = (GMimeFilterHeaders *) g_object_newv (GMIME_TYPE_FILTER_HEADERS, 0, NULL);
+
+	return (GMimeFilter *) new_headers;
+}
+