Seeking

Most stream operations simply advance the stream pointer as the stream is read. The current stream position can always be obtained using fz_tell (deliberately similar to the standard ftell call):

$\begin{lstlisting} /* fz_tell: return the current reading position within a stream */ int64_t fz_tell(fz_context *ctx, fz_stream *stm); \end{lstlisting}$

Some streams allow you to seek within them, that is, to change the current stream pointer to a given offset. To do this, use fz_seek (deliberately similar to fseek):

$\begin{lstlisting} /* fz_seek: Seek within a stream. \par stm: The stream to se... ...k(fz_context *ctx, fz_stream *stm, int64_t offset, int whence); \end{lstlisting}$

In the event that a stream does not support seeking, an error will be thrown.

As fz_seek and fz_tell work at byte granularity, care should be exercised when reading streams bitwise. Always fz_sync_bits before expecting fz_tell to give you a value that you can safely fz_seek back to.