mailcap.c

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/* RFC1524 (mailcap file) implementation */
/* $Id: mailcap.c,v 1.87.2.4 2005/05/01 22:03:23 jonas Exp $ */

/* This file contains various functions for implementing a fair subset of
 * rfc1524.
 *
 * The rfc1524 defines a format for the Multimedia Mail Configuration, which is
 * the standard mailcap file format under Unix which specifies what external
 * programs should be used to view/compose/edit multimedia files based on
 * content type.
 *
 * Copyright (C) 1996-2000 Michael R. Elkins <[e-mail]>
 * Copyright (c) 2002-2004 The ELinks project
 *
 * This file was hijacked from the Mutt project <URL:http://www.mutt.org>
 * (version 1.4) on Saturday the 7th December 2002. It has been heavily
 * elinksified. */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "elinks.h"

#include "config/options.h"
#include "intl/gettext/libintl.h"
#include "mime/backend/common.h"
#include "mime/backend/mailcap.h"
#include "mime/mime.h"
#include "modules/module.h"
#include "osdep/osdep.h"		/* For exe() */
#include "sched/session.h"
#include "util/file.h"
#include "util/hash.h"
#include "util/lists.h"
#include "util/memory.h"
#include "util/string.h"

struct mailcap_hash_item {
	/* The entries associated with the type */
	struct list_head entries; /* -> struct mailcap_entry */

	/* The content type of all @entries. Must be last! */
	unsigned char type[1];
};

struct mailcap_entry {
	LIST_HEAD(struct mailcap_entry);

	/* To verify if command qualifies. Cannot contain %s formats. */
	unsigned char *testcommand;

	/* Used to inform the user of the type or handler. */
	unsigned char *description;

	/* Used to determine between an exact match and a wildtype match. Lower
	 * is better. Increased for each sourced file. */
	unsigned int priority;

	/* Whether the program "blocks" the term. */
	unsigned int needsterminal:1;

	/* If "| ${PAGER}" should be added. It would of course be better to
	 * pipe the output into a buffer and let ELinks display it but this
	 * will have to do for now. */
	unsigned int copiousoutput:1;

	/* The 'raw' unformatted (view)command from the mailcap files. */
	unsigned char command[1];
};

enum mailcap_option {
	MAILCAP_TREE,

	MAILCAP_ENABLE,
	MAILCAP_PATH,
	MAILCAP_ASK,
	MAILCAP_DESCRIPTION,
	MAILCAP_PRIORITIZE,

	MAILCAP_OPTIONS
};

static struct option_info mailcap_options[] = {
	INIT_OPT_TREE("mime", N_("Mailcap"),
		"mailcap", 0,
		N_("Options for mailcap support.")),

	INIT_OPT_BOOL("mime.mailcap", N_("Enable"),
		"enable", 0, 1,
		N_("Enable mailcap support.")),

	INIT_OPT_STRING("mime.mailcap", N_("Path"),
		"path", 0, DEFAULT_MAILCAP_PATH,
		N_("Mailcap search path. Colon-separated list of files.\n"
		"Leave as \"\" to use MAILCAP environment variable instead.")),

	INIT_OPT_BOOL("mime.mailcap", N_("Ask before opening"),
		"ask", 0, 1,
		N_("Ask before using the handlers defined by mailcap.")),

	INIT_OPT_INT("mime.mailcap", N_("Type query string"),
		"description", 0, 0, 2, 0,
		N_("Type of description to show in \"what to do with this file\"\n"
		"query dialog:\n"
		"0 is show \"mailcap\"\n"
		"1 is show program to be run\n"
		"2 is show mailcap description field if any; \"mailcap\" otherwise")),

	INIT_OPT_BOOL("mime.mailcap", N_("Prioritize entries by file"),
		"prioritize", 0, 1,
		N_("Prioritize entries by the order of the files in the mailcap\n"
		"path. This means that wildcard entries (like: image/*) will\n"
		"also be checked before deciding the handler.")),

	NULL_OPTION_INFO,
};

#define get_opt_mailcap(which)		mailcap_options[(which)].option
#define get_mailcap(which)		get_opt_mailcap(which).value
#define get_mailcap_ask()		get_mailcap(MAILCAP_ASK).number
#define get_mailcap_description()	get_mailcap(MAILCAP_DESCRIPTION).number
#define get_mailcap_enable()		get_mailcap(MAILCAP_ENABLE).number
#define get_mailcap_prioritize()	get_mailcap(MAILCAP_PRIORITIZE).number
#define get_mailcap_path()		get_mailcap(MAILCAP_PATH).string

/* State variables */
static struct hash *mailcap_map = NULL;
static int mailcap_map_size = 0;


static inline void
done_mailcap_entry(struct mailcap_entry *entry)
{
	if (!entry) return;
	mem_free_if(entry->testcommand);
	mem_free_if(entry->description);
	mem_free(entry);
}

/* Takes care of all initialization of mailcap entries.
 * Clear memory to make freeing it safer later and we get
 * needsterminal and copiousoutput initialized for free. */
static inline struct mailcap_entry *
init_mailcap_entry(unsigned char *command, int priority)
{
	struct mailcap_entry *entry;
	int commandlen = strlen(command);

	entry = mem_calloc(1, sizeof(*entry) + commandlen);
	if (!entry) return NULL;

	memcpy(entry->command, command, commandlen);

	entry->priority = priority;

	return entry;
}

static inline void
add_mailcap_entry(struct mailcap_entry *entry, unsigned char *type, int typelen)
{
	struct mailcap_hash_item *mitem;
	struct hash_item *item;

	/* Time to get the entry into the mailcap_map */
	/* First check if the type is already checked in */
	item = get_hash_item(mailcap_map, type, typelen);
	if (!item) {
		mitem = mem_alloc(sizeof(*mitem) + typelen);
		if (!mitem) {
			done_mailcap_entry(entry);
			return;
		}

		safe_strncpy(mitem->type, type, typelen + 1);

		init_list(mitem->entries);

		item = add_hash_item(mailcap_map, mitem->type, typelen, mitem);
		if (!item) {
			mem_free(mitem);
			done_mailcap_entry(entry);
			return;
		}
	} else if (item->value) {
		mitem = item->value;
	} else {
		done_mailcap_entry(entry);
		return;
	}

	add_to_list_end(mitem->entries, entry);
	mailcap_map_size++;
}

/* Parsing of a RFC1524 mailcap file */
/* The format is:
 *
 *	base/type; command; extradefs
 *
 * type can be * for matching all; base with no /type is an implicit
 * wildcard; command contains a %s for the filename to pass, default to pipe on
 * stdin; extradefs are of the form:
 *
 *	def1="definition"; def2="define \;";
 *
 * line wraps with a \ at the end of the line, # for comments. */
/* TODO handle default pipe. Maybe by prepending "cat |" to the command. */

/* Returns a NULL terminated RFC 1524 field, while modifying @next to point
 * to the next field. */
static unsigned char *
get_mailcap_field(unsigned char **next)
{
	unsigned char *field;
	unsigned char *fieldend;

	if (!next || !*next) return NULL;

	field = *next;
	skip_space(field);
	fieldend = field;

	/* End field at the next occurence of ';' but not escaped '\;' */
	do {
		/* Handle both if ';' is the first char or if it's escaped */
		if (*fieldend == ';')
			fieldend++;

		fieldend = strchr(fieldend, ';');
	} while (fieldend && *(fieldend-1) == '\\');

	if (fieldend) {
		*fieldend = '\0';
		*next = fieldend;
		fieldend--;
		(*next)++;
		skip_space(*next);
	} else {
		*next = NULL;
		fieldend = field + strlen(field) - 1;
	}

	/* Remove trailing whitespace */
	while (field <= fieldend && isspace(*fieldend))
		*fieldend-- = '\0';

	return field;
}

/* Parses specific fields (ex: the '=TestCommand' part of 'test=TestCommand').
 * Expects that @field is pointing right after the specifier (ex: 'test'
 * above). Allocates and returns a NULL terminated token, or NULL if parsing
 * fails. */

static unsigned char *
get_mailcap_field_text(unsigned char *field)
{
	skip_space(field);

	if (*field == '=') {
		field++;
		skip_space(field);

		return stracpy(field);
	}

	return NULL;
}

/* Parse optional extra definitions. Zero return value means syntax error  */
static inline int
parse_optional_fields(struct mailcap_entry *entry, unsigned char *line)
{
	while (0xf131d5) {
		unsigned char *field = get_mailcap_field(&line);

		if (!field) break;

		if (!strncasecmp(field, "needsterminal", 13)) {
				entry->needsterminal = 1;

		} else if (!strncasecmp(field, "copiousoutput", 13)) {
			entry->copiousoutput = 1;

		} else if (!strncasecmp(field, "test", 4)) {
			entry->testcommand = get_mailcap_field_text(field + 4);
			if (!entry->testcommand)
				return 0;

			/* Find out wether testing requires filename */
			for (field = entry->testcommand; *field; field++)
				if (*field == '%' && *(field+1) == 's') {
					mem_free(entry->testcommand);
					return 0;
				}

		} else if (!strncasecmp(field, "description", 11)) {
			entry->description = get_mailcap_field_text(field + 11);
			if (!entry->description)
				return 0;
		}
	}

	return 1;
}

/* Parses whole mailcap files line-by-line adding entries to the map
 * assigning them the given @priority */
static void
parse_mailcap_file(unsigned char *filename, unsigned int priority)
{
	FILE *file = fopen(filename, "rb");
	unsigned char *line = NULL;
	size_t linelen = MAX_STR_LEN;
	int lineno = 1;

	if (!file) return;

	while ((line = file_read_line(line, &linelen, file, &lineno))) {
		struct mailcap_entry *entry;
		unsigned char *linepos;
		unsigned char *command;
		unsigned char *basetypeend;
		unsigned char *type;
		int typelen;

		/* Ignore comments */
		if (*line == '#') continue;

		linepos = line;

		/* Get type */