Function dfs_seq_traverse

components/dfs/dfs_v2/src/dfs_seq_file.c:99–151

* @brief Traverse sequence file data with specified offset * * This function traverses the sequence file data starting from the specified offset. * It handles buffer overflow conditions by dynamically resizing the buffer when needed. * * @param[in,out] seq Pointer to sequence file structure * @param[in] offset Position to start traversing from * * @return int 0 on success, negative error c

 * @note Data output loop: start() -> show() -> next() -> show() -> ... -> next() -> stop()
 */
static int dfs_seq_traverse(struct dfs_seq_file *seq, off_t offset)
{
    off_t pos = 0;
    int error = 0;
    void *p;

    seq->index = 0;
    seq->count = seq->from = 0;
    if (!offset)
        return 0;

    if (!seq->buf)
    {
        seq->buf = dfs_seq_alloc(seq->size = PAGE_SIZE);
        if (!seq->buf)
            return -ENOMEM;
    }
    p = seq->ops->start(seq, &seq->index);
    while (p)
    {
        error = seq->ops->show(seq, p);
        if (error < 0)
            break;
        if (error)
        {
            error = 0;
            seq->count = 0;
        }
        if (dfs_seq_is_full(seq))
            goto Eoverflow;

        p = seq->ops->next(seq, p, &seq->index);
        if (pos + seq->count > offset)
        {
            seq->from = offset - pos;
            seq->count -= seq->from;
            break;
        }
        pos += seq->count;
        seq->count = 0;
        if (pos == offset)
            break;
    }
    seq->ops->stop(seq, p);
    return error;

Eoverflow:
    seq->ops->stop(seq, p);
    rt_free(seq->buf);
    seq->count = 0;
    seq->buf = dfs_seq_alloc(seq->size <<= 1);
    return !seq->buf ? -ENOMEM : -EAGAIN;
}

/**
 * @brief Read data from sequence file