#include "Lacing.h" #include "Cluster.h" #include "vint.h" bool nsmkv::Lacing::GetState(uint8_t flags, const uint8_t *data, size_t data_len, nsmkv::LacingState *state) { // TODO: error check by making sure data_len doesn't go below 0 switch(flags & BlockBinary::LACE_MASK) { case BlockBinary::NO_LACING: state->laces = 1; state->positions[0] = 0; state->sizes[0] = data_len; #ifdef WA_VALIDATE printf(" Lacing = NO_LACING\n"); #endif return true; case BlockBinary::EBML_LACING: { uint16_t number_of_frames = state->laces = *data++ + 1; uint64_t delta = vint_get_number_bytes(data[0]); state->sizes[0] = vint_read_ptr_len((uint8_t)delta, data); delta++; state->positions[0] = 1; state->positions[1] = 1+state->sizes[0]; for (uint16_t i=1;i<number_of_frames-1;i++) { uint8_t this_len = vint_get_number_bytes(data[delta]); state->sizes[i] = vsint_read_ptr_len(this_len, data+delta); state->sizes[i] += state->sizes[i-1]; state->positions[i+1] = state->positions[i] + state->sizes[i]; delta+=this_len + 1; } state->sizes[number_of_frames-1] = data_len - state->positions[number_of_frames-1] - delta; for (uint16_t i=0;i<number_of_frames;i++) { state->positions[i] += delta; } #ifdef WA_VALIDATE printf(" Lacing = EBML_LACING\n"); #endif } return true; case BlockBinary::XIPH_LACING: { const uint8_t *orig_data = data; uint16_t number_of_frames=state->laces = *data++ + 1; for (uint16_t i=0;i!=number_of_frames-1;i++) { size_t frame_len = 0; do { frame_len += *data; } while (data && *data++ == 255); state->sizes[i] = frame_len; } uint64_t delta = data - orig_data; uint64_t last_position = delta; uint64_t last_size = 0; for (uint16_t i=0;i!=number_of_frames;i++) { state->positions[i] = last_position + last_size; last_position = state->positions[i]; last_size = state->sizes[i]; } state->sizes[number_of_frames-1] = data_len - state->positions[number_of_frames-1]; #ifdef WA_VALIDATE printf(" Lacing = XIPH LACING\n"); #endif } return true; case BlockBinary::FIXED_LACING: { uint16_t number_of_frames=state->laces=data[0]+1; uint32_t size_per_frame = (uint32_t)(data_len-1) / number_of_frames; for (uint16_t i=0;i<number_of_frames;i++) { state->positions[i] = (uint64_t)(1 + size_per_frame*i); state->sizes[i] = size_per_frame; } #ifdef WA_VALIDATE printf(" Lacing = FIXED LACING\n"); #endif } return true; default: return false; } } bool nsmkv::Lacing::GetFrame(uint16_t frame_number, const uint8_t *data, size_t data_len, const uint8_t **frame, size_t *frame_len, const LacingState *state) { if (frame_number >= state->laces) return false; const uint8_t *lace = data + state->positions[frame_number]; size_t lace_len = (size_t)state->sizes[frame_number]; if (lace < data // if the lace starts before our data || (state->positions[frame_number] + lace_len) > data_len) // or extends out past our data { return false; } *frame = lace; *frame_len = lace_len; return true; }