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NAME
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Fid, Fidpool, allocfidpool, freefidpool, allocfid, closefid, lookupfid,
removefid, Req, Reqpool, allocreqpool, freereqpool, allocreq,
closereq, lookupreq, removereq – 9P fid, request tracking
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SYNOPSIS
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#include <u.h>
#include <libc.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>
typedef struct Fid
{
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ulong fid;
char omode; /* −1 if not open */
char *uid;
Qid qid;
File *file;
void *aux;
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} Fid;
typedef struct Req
{
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ulong tag;
Fcall ifcall;
Fcall ofcall;
Req *oldreq;
void *aux;
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} 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)
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DESCRIPTION
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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(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 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
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.
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SOURCE
SEE ALSO
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