/* 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 , based on code from * update-desktop-base.c which was originally written by * Ray Strode * * 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 #include #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, RFC 2077 and RFC 8081 */ static const char *registered_discrete_media_types[] = { "application", "audio", "font", "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", /* Implemented as an extension of RFC 822; used for MHTML, in addition to * application/x-mimearchive */ "multipart/related", /* 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* * * 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 := * * 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; }