Creates a new packfile structure that uses the functions specified in
the vtable instead of the standard functions. The data pointer by `vtable'
and `userdata' must remain available for the lifetime of the created
While the created packfile structure can be used with other Allegro
functions, there are two limitations. First, opening chunks using
pack_fopen_chunk() on top of the returned packfile is not possible at this
time. And packfile_password() does not have any effect on packfiles opened
On success, it returns a pointer to a PACKFILE structure, and on error it
returns NULL and stores an error code in `errno'.
The following projects include source code containing this keyword: