int guac_parser_read()

in src/libguac/parser.c [167:268]

• 60 lines of code
• 13 McCabe index (conditional complexity)

int guac_parser_read(guac_parser* parser, guac_socket* socket, int usec_timeout) {

    char* unparsed_end   = parser->__instructionbuf_unparsed_end;
    char* unparsed_start = parser->__instructionbuf_unparsed_start;
    char* instr_start    = parser->__instructionbuf_unparsed_start;
    char* buffer_end     = parser->__instructionbuf + sizeof(parser->__instructionbuf);

    /* Begin next instruction if previous was ended */
    if (parser->state == GUAC_PARSE_COMPLETE)
        guac_parser_reset(parser);

    while (parser->state != GUAC_PARSE_COMPLETE
        && parser->state != GUAC_PARSE_ERROR) {

        /* Add any available data to buffer */
        int parsed = guac_parser_append(parser, unparsed_start, unparsed_end - unparsed_start);

        /* Read more data if not enough data to parse */
        if (parsed == 0 && parser->state != GUAC_PARSE_ERROR) {

            int retval;

            /* If no space left to read, fail */
            if (unparsed_end == buffer_end) {

                /* Shift backward if possible */
                if (instr_start != parser->__instructionbuf) {

                    int i;

                    /* Shift buffer */
                    int offset = instr_start - parser->__instructionbuf;
                    memmove(parser->__instructionbuf, instr_start,
                            unparsed_end - instr_start);

                    /* Update tracking pointers */
                    unparsed_end -= offset;
                    unparsed_start -= offset;
                    instr_start = parser->__instructionbuf;

                    /* Update parsed elements, if any */
                    for (i=0; i < parser->__elementc; i++)
                        parser->__elementv[i] -= offset;

                }

                /* Otherwise, no memory to read */
                else {
                    guac_error = GUAC_STATUS_NO_MEMORY;
                    guac_error_message = "Instruction too long";
                    return -1;
                }

            }

            /* No instruction yet? Get more data ... */
            retval = guac_socket_select(socket, usec_timeout);
            if (retval <= 0)
                return -1;
           
            /* Attempt to fill buffer */
            retval = guac_socket_read(socket, unparsed_end,
                    buffer_end - unparsed_end);

            /* Set guac_error if read unsuccessful */
            if (retval < 0) {
                guac_error = GUAC_STATUS_SEE_ERRNO;
                guac_error_message = "Error filling instruction buffer";
                return -1;
            }

            /* EOF */
            if (retval == 0) {
                guac_error = GUAC_STATUS_CLOSED;
                guac_error_message = "End of stream reached while "
                                     "reading instruction";
                return -1;
            }

            /* Update internal buffer */
            unparsed_end += retval;

        }

        /* If data was parsed, advance buffer */
        else
            unparsed_start += parsed;

    } /* end while parsing data */

    /* Fail on error */
    if (parser->state == GUAC_PARSE_ERROR) {
        guac_error = GUAC_STATUS_PROTOCOL_ERROR;
        guac_error_message = "Instruction parse error";
        return -1;
    }

    parser->__instructionbuf_unparsed_start = unparsed_start;
    parser->__instructionbuf_unparsed_end = unparsed_end;
    return 0;

}