9P-FID(3) 9P-FID(3)
NAME
Fid, Fidpool, allocfidpool, freefidpool, allocfid, closefid,
lookupfid, removefid, Req, Reqpool, allocreqpool,
freereqpool, allocreq, closereq, lookupreq, removereq - 9P
fid, request tracking
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>
typedef struct Fid
{
ulong fid;
char omode; /* -1 if not open */
char *uid;
Qid qid;
File *file;
void *aux;
...
} Fid;
typedef struct Req
{
ulong tag;
Fcall ifcall;
Fcall ofcall;
Req *oldreq;
void *aux;
...
} Req;
Fidpool* allocfidpool(void (*destroy)(Fid*))
void freefidpool(Fidpool *p)
Fid* allocfid(Fidpool *p, ulong fid)
Fid* lookupfid(Fidpool *p, ulong fid)
void closefid(Fid *f)
void removefid(Fid *f)
Reqpool* allocreqpool(void (*destroy)(Req*))
void freereqpool(Reqpool *p)
Req* allocreq(Reqpool *p, ulong tag)
Req* lookupreq(Reqpool *p, ulong tag)
void closereq(Req *f)
void removereq(Req *r)
DESCRIPTION
These routines provide management of Fid and Req structures
Page 1 Plan 9 (printed 11/18/24)
9P-FID(3) 9P-FID(3)
from Fidpools and Reqpools. They are primarily used by the
9P server loop described in 9p(3).
Fid structures are intended to represent active fids in a 9P
connection, 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 9p-file(3)) corresponding to the fid. The
aux member is intended for use by the client to hold infor-
mation specific to a particular Fid. With the exception of
aux, these elements 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 num-
ber 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 closefid 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.
SOURCE
/usr/local/plan9/src/lib9p
SEE ALSO
9p(3), 9p-file(3)
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