The critical handling of circular buffer overflow carries the risk of memory misalignment and access exceptions.

[zelzmz]

Hi，
In buffer. c, the handling of overflow situations by the buffer_push_tail function is as follows:

if (tail_end < rb->tail) {

    if (rb->head < align_size) {

      LOGE("no enough space");
      return -1;
    }

    int *p = (int*)(rb->data + rb->tail);
    *p = size;
    memcpy(rb->data, data, size);    
    rb->tail = size;

  }

Size is the true length of the data and is not aligned.

[zelzmz]

My modification is like this:

int buffer_push_tail(Buffer* rb, const uint8_t* data, int size) {
  int free_space = (rb->size + rb->head - rb->tail - 1) % rb->size;

  int align_size = ALIGN32(size) + 4;

  if (align_size > free_space) {
    LOGE("no enough space");
    return -1;
  }

  int tail_end = (rb->tail + align_size) % rb->size;

  if (tail_end < rb->tail) {

    if (rb->head < align_size) {
      LOGE("no enough space");
      return -1;
    }

    int* p = (int*)(rb->data + rb->tail);
    *p = size;
    memcpy(rb->data, data, size);
    rb->tail = ALIGN32(size);

  } else {
    int* p = (int*)(rb->data + rb->tail);
    *p = size;
    memcpy(rb->data + rb->tail + 4, data, size);
    rb->tail = tail_end;
  }

  return size;
}

uint8_t* buffer_peak_head(Buffer* rb, int* size) {
  if (!rb || rb->head == rb->tail) {

    return NULL;
  }

  *size = *((int*)(rb->data + rb->head));

  int align_size = ALIGN32(*size) + 4;

  int head_end = (rb->head + align_size) % rb->size;

  if (head_end < rb->head) {
    return rb->data;

  } else {

    return rb->data + (rb->head + 4);
  }
}

void buffer_pop_head(Buffer* rb) {
  if (!rb || rb->head == rb->tail) {
    return;
  }

  int* size = (int*)(rb->data + rb->head);

  int align_size = ALIGN32(*size) + 4;

  int head_end = (rb->head + align_size) % rb->size;

  if (head_end < rb->head) {
    rb->head = ALIGN32(*size);

  } else {

    rb->head = rb->head + align_size;
  }
}

This modification is relatively simple but wastes space. Let's see if we need to further optimize it.