// Even relatively modest values like 100 would work fine.
#define LOTS_OF_BITS 0x40000000
-int vp9_reader_init(vp9_reader *r, const uint8_t *buffer, size_t size) {
+int vp9_reader_init(vp9_reader *r,
+ const uint8_t *buffer,
+ size_t size,
+ vpx_decrypt_cb decrypt_cb,
+ void *decrypt_state) {
if (size && !buffer) {
return 1;
} else {
r->value = 0;
r->count = -8;
r->range = 255;
+ r->decrypt_cb = decrypt_cb;
+ r->decrypt_state = decrypt_state;
vp9_reader_fill(r);
return vp9_read_bit(r) != 0; // marker bit
}
void vp9_reader_fill(vp9_reader *r) {
const uint8_t *const buffer_end = r->buffer_end;
const uint8_t *buffer = r->buffer;
+ const uint8_t *buffer_start = buffer;
BD_VALUE value = r->value;
int count = r->count;
int shift = BD_VALUE_SIZE - CHAR_BIT - (count + CHAR_BIT);
int loop_end = 0;
- const int bits_left = (int)((buffer_end - buffer) * CHAR_BIT);
- const int x = shift + CHAR_BIT - bits_left;
+ const size_t bytes_left = buffer_end - buffer;
+ const size_t bits_left = bytes_left * CHAR_BIT;
+ const int x = (int)(shift + CHAR_BIT - bits_left);
+
+ if (r->decrypt_cb) {
+ size_t n = MIN(sizeof(r->clear_buffer), bytes_left);
+ r->decrypt_cb(r->decrypt_state, buffer, r->clear_buffer, (int)n);
+ buffer = r->clear_buffer;
+ buffer_start = r->clear_buffer;
+ }
if (x >= 0) {
count += LOTS_OF_BITS;
}
}
- r->buffer = buffer;
+ // NOTE: Variable 'buffer' may not relate to 'r->buffer' after decryption,
+ // so we increase 'r->buffer' by the amount that 'buffer' moved, rather than
+ // assign 'buffer' to 'r->buffer'.
+ r->buffer += buffer - buffer_start;
r->value = value;
r->count = count;
}