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+/* mimeutils.c: useful functions related to mime types
+ * vim: set ts=2 sw=2 et: */
+
+/*
+ * Copyright (C) 2004 Red Hat, Inc.
+ * Copyright (C) 2008 Novell, Inc.
+ *
+ * Written by Vincent Untz <vuntz@gnome.org>, based on code from
+ * update-desktop-base.c which was originally written by
+ * Ray Strode <rstrode@redhat.com>
+ *
+ * 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 2
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ */
+
+/* Related documentation:
+ * + Registered media types: http://www.iana.org/assignments/media-types/
+ * + RFC about MIME, with the BNF grammar: http://tools.ietf.org/html/rfc2045
+ * + RFC about media types: http://tools.ietf.org/html/rfc2046
+ * + RFC about the model media type: http://tools.ietf.org/html/rfc2077
+ */
+
+#include <string.h>
+
+#include <glib.h>
+
+#include "mimeutils.h"
+
+/* Not registered with IANA, but used on a free desktop */
+static const char *known_fdo_media_types[] = {
+ "inode", "x-content", "x-scheme-handler",
+ /* The chemical media type was never really proposed to IANA, but is
+ * well-known and in use by various applications out there. There are
+ * also some guidelines to not abuse it.
+ * http://www.ch.ic.ac.uk/chemime/ */
+ "chemical"
+};
+
+static const char *known_old_fdo_media_types[] = {
+ "x-directory"
+};
+
+/* Defined in RFC 2045/2046 and RFC 2077 */
+static const char *registered_discrete_media_types[] = {
+ "application", "audio", "image", "model", "text", "video"
+};
+
+/* Defined in RFC 2045/2046 */
+static const char *registered_composite_media_types[] = {
+ "message", "multipart"
+};
+
+static const char *registered_not_used_media_types[] = {
+ "example"
+};
+
+/* A few mime types that are not valid strictly-speaking (or discouraged
+ * according to the above media type), but that we know should be valid */
+static const char *valid_exceptions_mime_types[] = {
+ /* mail: a mail saved in a file will have this mime type */
+ "message/rfc822",
+ /* some multimedia mime type; it clearly doesn't respect the mime type rules,
+ * but it's widely deployed */
+ "misc/ultravox"
+};
+
+static struct {
+ const char *mime_type;
+ const char *should_be;
+} alias_to_replace_mime_types[] = {
+ { "flv-application/octet-stream", "video/x-flv" },
+ { "zz-application/zz-winassoc-123", "application/vnd.lotus-1-2-3" }, /* alias to be added in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=41989 */
+ { "zz-application/zz-winassoc-cab", "application/vnd.ms-cab-compressed" }, /* alias to be added in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=41989 */
+ { "zz-application/zz-winassoc-cdr", "application/vnd.corel-draw" },
+ { "zz-application/zz-winassoc-doc", "application/vnd.ms-word" }, /* alias to be added in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=41989 */
+ { "zz-application/zz-winassoc-hlp", "application/winhlp" }, /* not yet in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=41708 */
+ { "zz-application/zz-winassoc-ini", "text/plain" },
+ { "zz-application/zz-winassoc-lwp", "application/vnd.lotus-wordpro" }, /* not yet in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=36036 */
+ { "zz-application/zz-winassoc-lzh", "application/x-lzh-compressed" }, /* not yet in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=41680 */
+ { "zz-application/zz-winassoc-mdb", "application/vnd.ms-access" }, /* alias to be added in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=41989 */
+ { "zz-application/zz-winassoc-uu", "text/x-uuencode" }, /* not yet in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=41684 */
+ { "zz-application/zz-winassoc-xls", "application/vnd.ms-excel" } /* alias to be added in shared-mime-info: https://bugs.freedesktop.org/show_bug.cgi?id=41989 */
+};
+
+#define IF_IS_IN(list, type) \
+ for (i = 0; i < G_N_ELEMENTS (list); i++) { \
+ if (strcmp (type, list[i]) == 0) \
+ break; \
+ } \
+ if (i < G_N_ELEMENTS (list))
+
+
+/* TODO: it might actually be nice to download at distcheck time all the
+ * registered subtypes and warn when using a non-registered non-experimental
+ * subtype.
+ */
+
+/* From the BNF grammar:
+ *
+ * token := 1*<any (US-ASCII) CHAR except SPACE, CTLs,
+ * or tspecials>
+ *
+ * tspecials := "(" / ")" / "<" / ">" / "@" /
+ * "," / ";" / ":" / "\" / <">
+ * "/" / "[" / "]" / "?" / "="
+ */
+static gboolean
+is_valid_mime_type_char (const guchar c)
+{
+ char invalid_chars[] = "()<>@,;:\\\"/[]?=";
+
+ /* Filter out control chars and space */
+ if ((c <= 32) || (c == 127))
+ return FALSE;
+
+ if (memchr (invalid_chars, c, sizeof (invalid_chars)) != NULL)
+ return FALSE;
+
+ return TRUE;
+}
+
+/* From the BNF grammar:
+ *
+ * x-token := <The two characters "X-" or "x-" followed, with
+ * no intervening white space, by any token>
+ *
+ * From RFC 2046:
+ * In general, the use of "X-" top-level types is strongly discouraged.
+ * Implementors should invent subtypes of the existing types whenever
+ * possible. In many cases, a subtype of "application" will be more
+ * appropriate than a new top-level type.
+ */
+static MimeUtilsValidity
+is_valid_media_type (const char *media_type,
+ char **error)
+{
+ unsigned int i;
+
+ /* Handle known_fdo_media_types before X- types because it contains one X-
+ * type */
+ IF_IS_IN (known_fdo_media_types, media_type)
+ return MU_VALID;
+
+ IF_IS_IN (known_old_fdo_media_types, media_type) {
+ if (error)
+ *error = g_strdup_printf ("\"%s\" is an old media type that should be "
+ "replaced with a modern equivalent", media_type);
+ return MU_DISCOURAGED;
+ }
+
+ if (g_ascii_strncasecmp (media_type, "X-", 2) == 0) {
+ for (i = 2; media_type[i]; i++) {
+ if (!is_valid_mime_type_char (media_type[i])) {
+ if (error)
+ *error = g_strdup_printf ("\"%s\" a media type that contains "
+ "an invalid character", media_type);
+ return MU_INVALID;
+ }
+ }
+
+ if (error)
+ *error = g_strdup_printf ("the use of \"%s\" as media type is strongly "
+ "discouraged in favor of a subtype of the "
+ "\"application\" media type", media_type);
+
+ return MU_DISCOURAGED;
+ }
+
+ IF_IS_IN (registered_discrete_media_types, media_type)
+ return MU_VALID;
+
+ IF_IS_IN (registered_composite_media_types, media_type) {
+ if (error)
+ *error = g_strdup_printf ("\"%s\" is a media type that probably does "
+ "not make sense in this context", media_type);
+ return MU_DISCOURAGED;
+ }
+
+ IF_IS_IN (registered_not_used_media_types, media_type) {
+ if (error)
+ *error = g_strdup_printf ("\"%s\" is a media type that must not "
+ "be used", media_type);
+ return MU_INVALID;
+ }
+
+ if (error)
+ *error = g_strdup_printf ("\"%s\" is an unregistered media type",
+ media_type);
+
+ return MU_INVALID;
+}
+
+MimeUtilsValidity
+mu_mime_type_is_valid (const char *mime_type,
+ char **error)
+{
+ unsigned int i;
+ char *media_type;
+ char *subtype;
+ MimeUtilsValidity media_type_validity;
+
+ if (error)
+ *error = NULL;
+
+ media_type = g_strdup (mime_type);
+ subtype = strchr (media_type, '/');
+
+ if (!subtype) {
+ if (error)
+ *error = g_strdup_printf ("\"%s\" does not contain a subtype",
+ mime_type);
+ g_free (media_type);
+ return MU_INVALID;
+ }
+
+ subtype[0] = '\0';
+ subtype++;
+
+ if (subtype[0] == '\0') {
+ if (error)
+ *error = g_strdup_printf ("\"%s\" contains an empty subtype",
+ mime_type);
+ g_free (media_type);
+ return MU_INVALID;
+ }
+
+ for (; subtype[0] != '\0'; subtype++) {
+ if (!is_valid_mime_type_char (subtype[0])) {
+ if (error)
+ *error = g_strdup_printf ("\"%s\" contains an invalid character in "
+ "the subtype", mime_type);
+
+ g_free (media_type);
+ return MU_INVALID;
+ }
+ }
+
+ media_type_validity = is_valid_media_type (media_type, error);
+ g_free (media_type);
+
+ /* Let's end with the exceptions. We do this at the end to avoid doing more
+ * work in most cases. */
+
+ if (media_type_validity != MU_VALID) {
+ IF_IS_IN (valid_exceptions_mime_types, mime_type) {
+ if (error && *error) {
+ g_free (*error);
+ *error = NULL;
+ }
+
+ return MU_VALID;
+ }
+ }
+
+ /* If the mime type is already discouraged, then it won't be an improvement
+ * to say that it's discouraged because it's an alias to something else. So
+ * we just handle invalid mime types here. */
+ if (media_type_validity == MU_INVALID) {
+ for (i = 0; i < G_N_ELEMENTS (alias_to_replace_mime_types); i++) {
+ if (strcmp (mime_type, alias_to_replace_mime_types[i].mime_type) == 0)
+ break;
+ }
+
+ if (i < G_N_ELEMENTS (alias_to_replace_mime_types)) {
+ if (error) {
+ if (*error)
+ g_free (*error);
+
+ *error = g_strdup_printf ("\"%s\" should be replaced with \"%s\"",
+ mime_type,
+ alias_to_replace_mime_types[i].should_be);
+ }
+
+ return MU_DISCOURAGED;
+ }
+ }
+
+ return media_type_validity;
+}
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