9PFID(2)9PFID(2)
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;
Fid *fid;
Fid *afid;
Fid *newfid;
...
} 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)
DESCRIPTION
These routines provide management of
Fid
and
Req
structures from
Fidpools
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 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
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 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 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 reference 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 equivalent 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.
SOURCE
/sys/src/lib9p
SEE
9p(2),
9pfile(2)