term% cat index.txt
9PFID(2) System Calls Manual 9PFID(2)
Fid, Fidpool, allocfidpool, freefidpool, allocfid, closefid, lookupfid,
removefid, Req, Reqpool, allocreqpool, freereqpool, allocreq, closereq,
lookupreq, removereq - 9P fid, request tracking
typedef struct Fid
char omode; /* -1 if not open */
typedef struct Req
Fidpool* allocfidpool(void (*destroy)(Fid*))
void freefidpool(Fidpool *p)
Fid* allocfid(Fidpool *p, ulong fid)
Fid* lookupfid(Fidpool *p, ulong fid)
Fid* removefid(Fidpool *p, ulong fid);
void closefid(Fid *f)
Reqpool* allocreqpool(void (*destroy)(Req*))
void freereqpool(Reqpool *p)
Req* allocreq(Reqpool *p, ulong tag)
Req* lookupreq(Reqpool *p, ulong tag)
Req* removereq(Reqpool *p, ulong tag);
void closereq(Req *f)
These routines provide management of Fid and Req structures from Fid‐
pools and Reqpools. They are primarily used by the 9P server loop
described in 9p(2).
Fid structures are intended to represent active fids in a 9P connec‐
tion, as Chan structures do in the Plan 9 kernel. The fid element is
the integer fid used in the 9P connection. Omode is the mode under
which the fid was opened, or -1 if this fid has not been opened yet.
Note that in addition to the values OREAD, OWRITE, and ORDWR, omode can
contain the various flags permissible in an open call. To ignore the
flags, use omode&OMASK. Omode should not be changed by the client.
The fid derives from a successful authentication by uid. Qid contains
the qid returned in the last successful walk or create transaction
involving the fid. In a file tree-based server, the Fid's file element
points at a File structure (see 9pfile(2)) corresponding to the fid.
The aux member is intended for use by the client to hold information
specific to a particular Fid. With the exception of aux, these ele‐
ments should be treated as read-only by the client.
Allocfidpool creates a new Fidpool. Freefidpool destroys such a pool.
Allocfid returns a new Fid whose fid number is fid. There must not
already be an extant Fid with that number in the pool. Once a Fid has
been allocated, it can be looked up by fid number using lookupfid.
Fids are reference counted: both allocfid and lookupfid increment the
reference count on the Fid structure before returning. When a refer‐
ence to a Fid is no longer needed, closefid should be called to note
the destruction of the reference. When the last reference to a Fid is
removed, if destroy (supplied when creating the fid pool) is not zero,
it is called with the Fid as a parameter. It should perform whatever
cleanup is necessary regarding the aux element. Removefid is equiva‐
lent to lookupfid but also removes the Fid from the pool. Note that
due to lingering references, the return of removefid may not mean that
destroy has been called.
Allocreqpool, freereqpool, allocreq, lookupreq, closereq, and removereq
are analogous but operate on Reqpools and Req structures.