[evolution/calendar-xfb: 2/9] added helper functions for XFB data (type)

[Christian Hilberg <chilberg src gnome org>]

commit e1b48820a4958c915411a4fb5ba84718c759c9ae
Author: Christian Hilberg <chilberg src gnome org>
Date:   Fri Nov 9 10:27:08 2012 +0100

    added helper functions for XFB data (type)
    
    * since EMeetingXfbData will be part of the freebusy
      GArray data (EMeetingFreeBusyPeriod), it gets allocated
      when EMeetingFreeBusyPeriod is, we just need to
      clear/set it (hence no new()/free(), but clear()/set())
    * e_meeting_xfb_utf8_string_new_from_ical() takes care
      of UTF-8 validation and length limitation of the
      summary/location strings we get since these will be
      displayed as tooltips for busy periods

 calendar/gui/e-meeting-utils.c |  183 ++++++++++++++++++++++++++++++++++++++++
 calendar/gui/e-meeting-utils.h |   14 +++-
 2 files changed, 196 insertions(+), 1 deletions(-)
---
diff --git a/calendar/gui/e-meeting-utils.c b/calendar/gui/e-meeting-utils.c
index 89149e7..ca66990 100644
--- a/calendar/gui/e-meeting-utils.c
+++ b/calendar/gui/e-meeting-utils.c
@@ -25,8 +25,57 @@
 #include <config.h>
 #endif
 
+#include <string.h>
+
 #include "e-meeting-utils.h"
 
+
+/* this is a dupe of e_util_utf8_data_make_valid()
+ * from libedataserver (which we do not link to
+ * in this module presently). _g_utf8_make_valid()
+ * really should be a public function...
+ */
+static gchar*
+util_utf8_data_make_valid (const gchar *data,
+                           gsize data_bytes)
+{
+	/* almost identical copy of glib's _g_utf8_make_valid() */
+	GString *string;
+	const gchar *remainder, *invalid;
+	gint remaining_bytes, valid_bytes;
+
+	g_return_val_if_fail (data != NULL, NULL);
+
+	string = NULL;
+	remainder = (gchar *) data,
+	remaining_bytes = data_bytes;
+
+	while (remaining_bytes != 0) {
+		if (g_utf8_validate (remainder, remaining_bytes, &invalid))
+			break;
+		valid_bytes = invalid - remainder;
+
+		if (string == NULL)
+			string = g_string_sized_new (remaining_bytes);
+
+		g_string_append_len (string, remainder, valid_bytes);
+		/* append U+FFFD REPLACEMENT CHARACTER */
+		g_string_append (string, "\357\277\275");
+
+		remaining_bytes -= valid_bytes + 1;
+		remainder = invalid + 1;
+	}
+
+	if (string == NULL)
+		return g_strndup ((gchar *) data, data_bytes);
+
+	g_string_append (string, remainder);
+
+	g_warn_if_fail (g_utf8_validate (string->str, -1, NULL));
+
+	return g_string_free (string, FALSE);
+}
+
 gint
 e_meeting_time_compare_times (EMeetingTime *time1,
                               EMeetingTime *time2)
@@ -51,3 +100,137 @@ e_meeting_time_compare_times (EMeetingTime *time1,
 	/* The start times are exactly the same. */
 	return 0;
 }
+
+void
+e_meeting_xfb_data_init (EMeetingXfbData *xfb)
+{
+	g_return_if_fail (xfb != NULL);
+
+	xfb->summary = NULL;
+	xfb->location = NULL;
+}
+
+void
+e_meeting_xfb_data_set (EMeetingXfbData *xfb,
+                        const gchar *summary,
+                        const gchar *location)
+{
+	g_return_if_fail (xfb != NULL);
+	
+	e_meeting_xfb_data_clear (xfb);
+	xfb->summary = g_strdup (summary);
+	xfb->location = g_strdup (location);
+}
+
+void
+e_meeting_xfb_data_clear (EMeetingXfbData *xfb)
+{
+	g_return_if_fail (xfb != NULL);
+
+	/* clearing the contents of xfb,
+	 * but not the xfb structure itself
+	 */
+
+	if (xfb->summary != NULL) {
+		g_free (xfb->summary);
+		xfb->summary = NULL;
+	}
+	if (xfb->location != NULL) {
+		g_free (xfb->location);
+		xfb->location = NULL;
+	}
+}
+
+/* Creates an XFB string from a string property of a vfreebusy
+ * icalproperty. The ical string we read may be base64 encoded, but
+ * we get no reliable indication whether it really is. So we
+ * try to base64-decode, and failing that, assume the string
+ * is plain. The result is validated for UTF-8. We try to convert
+ * to UTF-8 from locale if the input is no valid UTF-8, and failing
+ * that, force the result into valid UTF-8. We also limit the
+ * length of the resulting string, since it gets displayed as a
+ * tooltip text in the meeting time selector.
+ */
+gchar*
+e_meeting_xfb_utf8_string_new_from_ical (const gchar *icalstring,
+                                         gsize max_len)
+{
+	guchar *u_tmp = NULL;
+	gchar *tmp = NULL;
+	gchar *utf8s = NULL;
+	gsize in_len = 0;
+	gsize out_len = 0;
+	GError *tmp_err = NULL;
+
+	g_return_val_if_fail (max_len > 4, NULL);
+	
+	if (icalstring == NULL)
+		return NULL;
+
+	/* The icalstring may or may not be base64 encoded,
+	 * which leaves us with guessing - we try decoding, if
+	 * that fails we try plain. If icalstring is meant to
+	 * be plain, but is valid base64 nonetheless, then we've
+	 * lost (since we cannot reliably detect that case)
+	 */
+
+	u_tmp = g_base64_decode (icalstring, &out_len);
+	if (u_tmp == NULL)
+		u_tmp = (guchar *) g_strdup (icalstring);
+
+	/* ical does not carry charset hints, so we
+	 * try utf-8 first, then conversion to locale.
+	 * If both fail we retrieve as many 
+	 */
+
+	/* if we have valid UTF-8, we're done converting */
+	if (g_utf8_validate ((const gchar *) u_tmp, -1, NULL))
+		goto valid;
+
+	/* no valid UTF-8, trying to convert to it
+	 * according to system locale
+	 */
+	tmp = g_locale_to_utf8 ((const gchar *) u_tmp,
+	                        -1,
+	                        &in_len,
+	                        &out_len,
+	                        &tmp_err);
+
+	if (tmp_err == NULL)
+		goto valid;
+
+	g_warning ("%s() %s", __func__, tmp_err->message);
+	g_error_free (tmp_err);
+
+	/* still no success, forcing it into UTF-8, using
+	 * replacement chars to replace invalid ones
+	 */
+	tmp = util_utf8_data_make_valid ((const gchar *) u_tmp,
+	                                 strlen ((const gchar *) u_tmp));
+ valid:
+	if (tmp == NULL)
+		tmp = (gchar *) u_tmp;
+	else
+		g_free (u_tmp);
+
+	/* now that we're (forcibly) valid UTF-8, we can
+	 * limit the size of the UTF-8 string for display
+	 */
+
+	if (g_utf8_strlen (tmp, -1) > (glong) max_len) {
+		g_warning ("%s() XFB string longer than %i characters, clipping",
+		           __func__, (gint) max_len);
+		/* insert NULL termination to where we want to
+		 * clip, take care to hit UTF-8 character boundary
+		 */
+		utf8s = g_utf8_offset_to_pointer (tmp, (glong) max_len - 4);
+		*utf8s = '\0';
+		/* create shortened UTF-8 string */
+		utf8s = g_strdup_printf ("%s ...", tmp);
+		g_free (tmp);
+	} else {
+		utf8s = tmp;
+	}
+	
+	return utf8s;
+}
diff --git a/calendar/gui/e-meeting-utils.h b/calendar/gui/e-meeting-utils.h
index 7c275b1..0de391d 100644
--- a/calendar/gui/e-meeting-utils.h
+++ b/calendar/gui/e-meeting-utils.h
@@ -33,7 +33,19 @@ G_BEGIN_DECLS
 gint e_meeting_time_compare_times (EMeetingTime *time1,
 				   EMeetingTime *time2);
 
+/* Extended free/busy (XFB) helpers */
+
+void e_meeting_xfb_data_init (EMeetingXfbData *xfb);
+
+void e_meeting_xfb_data_set (EMeetingXfbData *xfb,
+                             const gchar *summary,
+                             const gchar *location);
+
+void e_meeting_xfb_data_clear (EMeetingXfbData *xfb);
+
+gchar * e_meeting_xfb_utf8_string_new_from_ical (const gchar *icalstring,
+                                                 gsize max_len);
+
 G_END_DECLS
 
 #endif /* _E_MEETING_UTILS_H_ */
-