ASSUAN uses a so-called context to store a connection’s state. The following data type is used for that:
assuan_context_t type is a pointer to an object maintained
internally by the library. Contexts are allocated with
assuan_new_ext and released with
assuan_release. Other functions take this data type to access
the state created by these functions.
assuan_fd_t is a file descriptor (in Unix) or a system
handle (in Windows). The special value
used to specify invalid Assuan file descriptors.
Create an assuan file descriptor from a POSIX (libc) file descriptor
fd. On Unix, this is equivalent to
dup, while on Windows
this will retrieve the underlying system handle with
_get_osfhandle and duplicate that.