filetype.c

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/*
 * Copyright 2007 Rob Kendrick <rjek@netsurf-browser.org>
 * Copyright 2007 Vincent Sanders <vince@debian.org>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf 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; version 2 of the License.
 *
 * NetSurf 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, see <http://www.gnu.org/licenses/>.
 */
 
/**
 * \file
 * file extension to mimetype mapping for the monkey frontend
 *
 * allows monkey frontend to map file extension to mime types using a
 * default builtin list and /etc/mime.types file if present.
 *
 * mime type and content type handling is derived from the BNF in
 * RFC822 section 3.3, RFC2045 section 5.1 and RFC6838 section
 * 4.2. Upshot is their charset and parsing is all a strict subset of
 * ASCII hence not using locale dependant ctype functions for parsing.
 */
 
#include <stdio.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <strings.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
 
#include "utils/log.h"
#include "utils/ascii.h"
#include "utils/hashtable.h"
 
#include "monkey/filetype.h"
 
#define HASH_SIZE 117
#define MAX_LINE_LEN 256
 
static struct hash_table *mime_hash = NULL;
 
void monkey_fetch_filetype_init(const char *mimefile)
{
        struct stat statbuf;
        FILE *fh = NULL;
 
        mime_hash = hash_create(HASH_SIZE);
 
        /* Some OSes (mentioning no Solarises) have a worthlessly tiny
         * /etc/mime.types that don't include essential things, so we
         * pre-seed our hash with the essentials.  These will get
         * over-ridden if they are mentioned in the mime.types file.
         */
 
        hash_add(mime_hash, "css", "text/css");
        hash_add(mime_hash, "htm", "text/html");
        hash_add(mime_hash, "html", "text/html");
        hash_add(mime_hash, "jpg", "image/jpeg");
        hash_add(mime_hash, "jpeg", "image/jpeg");
        hash_add(mime_hash, "bmp", "image/bmp");
        hash_add(mime_hash, "gif", "image/gif");
        hash_add(mime_hash, "png", "image/png");
        hash_add(mime_hash, "ico", "image/ico");
        hash_add(mime_hash, "jng", "image/jng");
        hash_add(mime_hash, "mng", "image/mng");
        hash_add(mime_hash, "webp", "image/webp");
        hash_add(mime_hash, "spr", "image/x-riscos-sprite");
 
        /* first, check to see if /etc/mime.types in preference */
        if ((stat("/etc/mime.types", &statbuf) == 0) &&
                        S_ISREG(statbuf.st_mode)) {
                mimefile = "/etc/mime.types";
 
        }
 
        fh = fopen(mimefile, "r");
 
        if (fh == NULL) {
                NSLOG(netsurf, INFO,
                      "Unable to open a mime.types file, so using a minimal one for you.");
                return;
        }
 
        while (!feof(fh)) {
                char line[MAX_LINE_LEN], *ptr, *type, *ext;
                if (fgets(line, MAX_LINE_LEN, fh) == NULL)
                        break;
                if (!feof(fh) && line[0] != '#') {
                        ptr = line;
 
                        /* search for the first non-whitespace character */
                        while (ascii_is_space(*ptr))
                                ptr++;
 
                        /* is this line empty other than leading whitespace? */
                        if (*ptr == '\n' || *ptr == '\0')
                                continue;
 
                        type = ptr;
 
                        /* search for the first whitespace char or NUL or
                         * NL */
                        while (*ptr && (!ascii_is_space(*ptr)))
                                ptr++;
 
                        if (*ptr == '\0' || *ptr == '\n') {
                                /* this mimetype has no extensions - read next
                                 * line.
                                 */
                                continue;
                        }
 
                        *ptr++ = '\0';
 
                        /* search for the first non-whitespace character which
                         * will be the first filename extenion */
                        while (ascii_is_space(*ptr))
                                ptr++;
 
                        while(true) {
                                ext = ptr;
 
                                /* search for the first whitespace char or
                                 * NUL or NL which is the end of the ext.
                                 */
                                while (*ptr && (!ascii_is_space(*ptr)))
                                        ptr++;
 
                                if (*ptr == '\0' || *ptr == '\n') {
                                        /* special case for last extension on
                                         * the line
                                         */
                                        *ptr = '\0';
                                        hash_add(mime_hash, ext, type);
                                        break;
                                }
 
                                *ptr++ = '\0';
                                hash_add(mime_hash, ext, type);
 
                                /* search for the first non-whitespace char or
                                 * NUL or NL, to find start of next ext.
                                 */
                                while (*ptr &&
                                       (ascii_is_space(*ptr)) &&
                                       *ptr != '\n') {
                                        ptr++;
                                }
                        }
                }
        }
 
        fclose(fh);
}
 
void monkey_fetch_filetype_fin(void)
{
        hash_destroy(mime_hash);
}
 
/**
 * Determine the MIME type of a local file.
 *
 * @note used in file fetcher
 *
 * \param unix_path Unix style path to file on disk
 * \return Pointer to static MIME type string (should not be freed) not NULL.
 *         invalidated on next call to fetch_filetype.
 */
const char *monkey_fetch_filetype(const char *unix_path)
{
        struct stat statbuf;
        char *ext;
        const char *ptr;
        char *lowerchar;
        const char *type;
        int l;
 
        if (stat(unix_path, &statbuf) != 0) {
                /* error calling stat, the file has probably become
                 * inacessible, this routine cannot fail so just
                 * return the default mime type.
                 */
                return "text/plain";
        }
        if (S_ISDIR(statbuf.st_mode)) {
                return "application/x-netsurf-directory";
        }
 
        l = strlen(unix_path);
        if ((3 < l) && (strcasecmp(unix_path + l - 4, ",f79") == 0)) {
                return "text/css";
        }
 
        if (strchr(unix_path, '.') == NULL) {
                /* no extension anywhere! */
                return "text/plain";
        }
 
        ptr = unix_path + strlen(unix_path);
        while (*ptr != '.' && *ptr != '/')
                ptr--;
 
        if (*ptr != '.') {
                return "text/plain";
        }
 
        ext = strdup(ptr + 1);  /* skip the . */
 
        /* the hash table only contains lower-case versions - make sure this
         * copy is lower case too.
         */
        lowerchar = ext;
        while(*lowerchar) {
                *lowerchar = ascii_to_lower(*lowerchar);
                lowerchar++;
        }
 
        type = hash_get(mime_hash, ext);
        free(ext);
 
        return type != NULL ? type : "text/plain";
}