mod_mime_magic.c

Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

    struct magic_rsl_s *next;   /* pointer to next fragment */
} magic_rsl;

/*
 * Apache module configuration structures
 */

/* per-server info */
typedef struct {
    const char *magicfile;    /* where magic be found */
    struct magic *magic;      /* head of magic config list */
    struct magic *last;
} magic_server_config_rec;

/* per-request info */
typedef struct {
    magic_rsl *head;          /* result string list */
    magic_rsl *tail;
    unsigned suf_recursion;   /* recursion depth in suffix check */
} magic_req_rec;

/*
 * configuration functions - called by Apache API routines
 */

module AP_MODULE_DECLARE_DATA mime_magic_module;

static void *create_magic_server_config(apr_pool_t *p, server_rec *d)
{
    /* allocate the config - use pcalloc because it needs to be zeroed */
    return apr_pcalloc(p, sizeof(magic_server_config_rec));
}

static void *merge_magic_server_config(apr_pool_t *p, void *basev, void *addv)
{
    magic_server_config_rec *base = (magic_server_config_rec *) basev;
    magic_server_config_rec *add = (magic_server_config_rec *) addv;
    magic_server_config_rec *new = (magic_server_config_rec *)
                            apr_palloc(p, sizeof(magic_server_config_rec));

    new->magicfile = add->magicfile ? add->magicfile : base->magicfile;
    new->magic = NULL;
    new->last = NULL;
    return new;
}

static const char *set_magicfile(cmd_parms *cmd, void *dummy, const char *arg)
{
    magic_server_config_rec *conf = (magic_server_config_rec *)
    ap_get_module_config(cmd->server->module_config,
                      &mime_magic_module);

    if (!conf) {
        return MODNAME ": server structure not allocated";
    }
    conf->magicfile = arg;
    return NULL;
}

/*
 * configuration file commands - exported to Apache API
 */

static const command_rec mime_magic_cmds[] =
{
    AP_INIT_TAKE1("MimeMagicFile", set_magicfile, NULL, RSRC_CONF,
     "Path to MIME Magic file (in file(1) format)"),
    {NULL}
};

/*
 * RSL (result string list) processing routines
 *
 * These collect strings that would have been printed in fragments by file(1)
 * into a list of magic_rsl structures with the strings. When complete,
 * they're concatenated together to become the MIME content and encoding
 * types.
 *
 * return value conventions for these functions: functions which return int:
 * failure = -1, other = result functions which return pointers: failure = 0,
 * other = result
 */

/* allocate a per-request structure and put it in the request record */
static magic_req_rec *magic_set_config(request_rec *r)
{
    magic_req_rec *req_dat = (magic_req_rec *) apr_palloc(r->pool,
                                                      sizeof(magic_req_rec));

    req_dat->head = req_dat->tail = (magic_rsl *) NULL;
    ap_set_module_config(r->request_config, &mime_magic_module, req_dat);
    return req_dat;
}

/* add a string to the result string list for this request */
/* it is the responsibility of the caller to allocate "str" */
static int magic_rsl_add(request_rec *r, char *str)
{
    magic_req_rec *req_dat = (magic_req_rec *)
                    ap_get_module_config(r->request_config, &mime_magic_module);
    magic_rsl *rsl;

    /* make sure we have a list to put it in */
    if (!req_dat) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, APR_EINVAL, r,
                    MODNAME ": request config should not be NULL");
        if (!(req_dat = magic_set_config(r))) {
            /* failure */
            return -1;
        }
    }

    /* allocate the list entry */
    rsl = (magic_rsl *) apr_palloc(r->pool, sizeof(magic_rsl));

    /* fill it */
    rsl->str = str;
    rsl->next = (magic_rsl *) NULL;

    /* append to the list */
    if (req_dat->head && req_dat->tail) {
        req_dat->tail->next = rsl;
        req_dat->tail = rsl;
    }
    else {
        req_dat->head = req_dat->tail = rsl;
    }

    /* success */
    return 0;
}

/* RSL hook for puts-type functions */
static int magic_rsl_puts(request_rec *r, char *str)
{
    return magic_rsl_add(r, str);
}

/* RSL hook for printf-type functions */
static int magic_rsl_printf(request_rec *r, char *str,...)
{
    va_list ap;

    char buf[MAXMIMESTRING];

    /* assemble the string into the buffer */
    va_start(ap, str);
    apr_vsnprintf(buf, sizeof(buf), str, ap);
    va_end(ap);

    /* add the buffer to the list */
    return magic_rsl_add(r, apr_pstrdup(r->pool, buf));
}

/* RSL hook for putchar-type functions */
static int magic_rsl_putchar(request_rec *r, char c)
{
    char str[2];

    /* high overhead for 1 char - just hope they don't do this much */
    str[0] = c;
    str[1] = '\0';
    return magic_rsl_add(r, str);
}

/* allocate and copy a contiguous string from a result string list */
static char *rsl_strdup(request_rec *r, int start_frag, int start_pos, int len)
{
    char *result;       /* return value */
    int cur_frag,       /* current fragment number/counter */
        cur_pos,        /* current position within fragment */
        res_pos;        /* position in result string */
    magic_rsl *frag;    /* list-traversal pointer */
    magic_req_rec *req_dat = (magic_req_rec *)
                    ap_get_module_config(r->request_config, &mime_magic_module);

    /* allocate the result string */
    result = (char *) apr_palloc(r->pool, len + 1);

    /* loop through and collect the string */
    res_pos = 0;
    for (frag = req_dat->head, cur_frag = 0;
         frag->next;
         frag = frag->next, cur_frag++) {
        /* loop to the first fragment */
        if (cur_frag < start_frag)
            continue;

        /* loop through and collect chars */
        for (cur_pos = (cur_frag == start_frag) ? start_pos : 0;
             frag->str[cur_pos];
             cur_pos++) {
            if (cur_frag >= start_frag
                && cur_pos >= start_pos
                && res_pos <= len) {
                result[res_pos++] = frag->str[cur_pos];
                if (res_pos > len) {
                    break;
                }
            }
        }
    }

    /* clean up and return */
    result[res_pos] = 0;
#if MIME_MAGIC_DEBUG
    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
             MODNAME ": rsl_strdup() %d chars: %s", res_pos - 1, result);
#endif
    return result;
}

/* states for the state-machine algorithm in magic_rsl_to_request() */
typedef enum {
    rsl_leading_space, rsl_type, rsl_subtype, rsl_separator, rsl_encoding
} rsl_states;

/* process the RSL and set the MIME info in the request record */
static int magic_rsl_to_request(request_rec *r)
{
    int cur_frag,         /* current fragment number/counter */
        cur_pos,          /* current position within fragment */
        type_frag,        /* content type starting point: fragment */
        type_pos,         /* content type starting point: position */
        type_len,         /* content type length */
        encoding_frag,    /* content encoding starting point: fragment */
        encoding_pos,     /* content encoding starting point: position */
        encoding_len;     /* content encoding length */

    magic_rsl *frag;      /* list-traversal pointer */
    rsl_states state;

    magic_req_rec *req_dat = (magic_req_rec *)
                    ap_get_module_config(r->request_config, &mime_magic_module);

    /* check if we have a result */
    if (!req_dat || !req_dat->head) {
        /* empty - no match, we defer to other Apache modules */
        return DECLINED;
    }

    /* start searching for the type and encoding */
    state = rsl_leading_space;
    type_frag = type_pos = type_len = 0;
    encoding_frag = encoding_pos = encoding_len = 0;
    for (frag = req_dat->head, cur_frag = 0;
         frag && frag->next;
         frag = frag->next, cur_frag++) {
        /* loop through the characters in the fragment */
        for (cur_pos = 0; frag->str[cur_pos]; cur_pos++) {
            if (apr_isspace(frag->str[cur_pos])) {
                /* process whitespace actions for each state */
                if (state == rsl_leading_space) {
                    /* eat whitespace in this state */
                    continue;
                }
                else if (state == rsl_type) {
                    /* whitespace: type has no slash! */
                    return DECLINED;
                }
                else if (state == rsl_subtype) {
                    /* whitespace: end of MIME type */
                    state++;
                    continue;
                }
                else if (state == rsl_separator) {
                    /* eat whitespace in this state */
                    continue;
                }
                else if (state == rsl_encoding) {
                    /* whitespace: end of MIME encoding */
                    /* we're done */
                    frag = req_dat->tail;
                    break;
                }
                else {
                    /* should not be possible */
                    /* abandon malfunctioning module */
                    ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                                MODNAME ": bad state %d (ws)", state);
                    return DECLINED;
                }
                /* NOTREACHED */
            }
            else if (state == rsl_type &&
                     frag->str[cur_pos] == '/') {
                /* copy the char and go to rsl_subtype state */
                type_len++;
                state++;
            }
            else {
                /* process non-space actions for each state */
                if (state == rsl_leading_space) {
                    /* non-space: begin MIME type */
                    state++;
                    type_frag = cur_frag;
                    type_pos = cur_pos;
                    type_len = 1;
                    continue;
                }
                else if (state == rsl_type ||
                         state == rsl_subtype) {
                    /* non-space: adds to type */
                    type_len++;
                    continue;
                }
                else if (state == rsl_separator) {
                    /* non-space: begin MIME encoding */
                    state++;
                    encoding_frag = cur_frag;
                    encoding_pos = cur_pos;
                    encoding_len = 1;
                    continue;
                }
                else if (state == rsl_encoding) {
                    /* non-space: adds to encoding */
                    encoding_len++;
                    continue;
                }
                else {
                    /* should not be possible */
                    /* abandon malfunctioning module */
                    ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                                MODNAME ": bad state %d (ns)", state);
                    return DECLINED;
                }
                /* NOTREACHED */
            }
            /* NOTREACHED */
        }
    }

    /* if we ended prior to state rsl_subtype, we had incomplete info */
    if (state != rsl_subtype && state != rsl_separator &&
        state != rsl_encoding) {
        /* defer to other modules */
        return DECLINED;
    }

    /* save the info in the request record */
    if (state == rsl_subtype || state == rsl_encoding ||
        state == rsl_encoding) {
        char *tmp;
        tmp = rsl_strdup(r, type_frag, type_pos, type_len);
        /* XXX: this could be done at config time I'm sure... but I'm
         * confused by all this magic_rsl stuff. -djg */
        ap_content_type_tolower(tmp);
        ap_set_content_type(r, tmp);
    }
    if (state == rsl_encoding) {
        char *tmp;
        tmp = rsl_strdup(r, encoding_frag,
                                         encoding_pos, encoding_len);
        /* XXX: this could be done at config time I'm sure... but I'm
         * confused by all this magic_rsl stuff. -djg */
        ap_str_tolower(tmp);
        r->content_encoding = tmp;
    }

    /* detect memory allocation or other errors */
    if (!r->content_type ||
        (state == rsl_encoding && !r->content_encoding)) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      MODNAME ": unexpected state %d; could be caused by bad "
                      "data in magic file",
                      state);
        return HTTP_INTERNAL_SERVER_ERROR;
    }

    /* success! */
    return OK;
}

/*
 * magic_process - process input file r        Apache API request record
 * (formerly called "process" in file command, prefix added for clarity) Opens
 * the file and reads a fixed-size buffer to begin processing the contents.
 */
static int magic_process(request_rec *r)
{
    apr_file_t *fd = NULL;
    unsigned char buf[HOWMANY + 1];  /* one extra for terminating '\0' */
    apr_size_t nbytes = 0;           /* number of bytes read from a datafile */
    int result;

    /*
     * first try judging the file based on its filesystem status
     */
    switch ((result = fsmagic(r, r->filename))) {
    case DONE:
        magic_rsl_putchar(r, '\n');
        return OK;
    case OK:
        break;
    default:
        /* fatal error, bail out */
        return result;
    }

    if (apr_file_open(&fd, r->filename, APR_READ, APR_OS_DEFAULT, r->pool) != APR_SUCCESS) {
        /* We can't open it, but we were able to stat it. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                    MODNAME ": can't read `%s'", r->filename);
        /* let some other handler decide what the problem is */
        return DECLINED;
    }

    /*
     * try looking at the first HOWMANY bytes
     */
    nbytes = sizeof(buf) - 1;
    if ((result = apr_file_read(fd, (char *) buf, &nbytes)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, result, r,
                    MODNAME ": read failed: %s", r->filename);
        return HTTP_INTERNAL_SERVER_ERROR;
    }

    if (nbytes == 0) {
        return DECLINED;
    }
    else {
        buf[nbytes++] = '\0';  /* null-terminate it */
        result = tryit(r, buf, nbytes, 1);
        if (result != OK) {
            return result;
        }
    }

    (void) apr_file_close(fd);
    (void) magic_rsl_putchar(r, '\n');

    return OK;
}


static int tryit(request_rec *r, unsigned char *buf, apr_size_t nb,
                 int checkzmagic)
{
    /*
     * Try compression stuff
     */
        if (checkzmagic == 1) {
                        if (zmagic(r, buf, nb) == 1)
                        return OK;
        }