def readinto(self, dst: BufferType) -> int:
"""Read exactly `len(dst)` bytes into `dst`, or raise EOFError.
Returns number of bytes read.
"""
buffer = self.buffer
offset = self.offset
if len(dst) > len(buffer) - offset:
raise EOFError
nread = memcpy(dst, 0, buffer, offset)
self.offset += nread
return nread
def write(self, src: bytes) -> int:
"""Write exactly `len(src)` bytes into buffer, or raise EOFError.
Returns number of bytes written.
"""
buffer = self.buffer
offset = self.offset
if len(src) > len(buffer) - offset:
raise EOFError
nwrite = memcpy(buffer, offset, src, 0)
self.offset += nwrite
return nwrite
