add ptrap
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75
sys/man/4/ptrap
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75
sys/man/4/ptrap
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@ -0,0 +1,75 @@
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.TH PTRAP 4
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.SH NAME
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ptrap \- \fIplumber\fR(4) filter
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.SH SYNOPSIS
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.B ptrap
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.I port
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[\fB!\fR]\fIregexp\fR
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[
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.I port
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[\fB!\fR]\fIregexp\fR ...
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]
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.SH DESCRIPTION
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.I Ptrap
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is a program that mounts itself over a
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.IR plumber (4)
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service mounted at
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.B /mnt/plumb
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and filters incoming messages according to the rules provided on the command line.
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.PP
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.I Ptrap
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accepts an arbitrary number of argument pairs; each pair consists of a port name
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.I port
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and a regular expression
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.I regexp
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(see
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.IR regexp (6)).
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Each incoming message that does not match
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.I regexp
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is discarded.
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The
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.I regexp
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can be optionally prefixed by
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.B !
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to indicate logical inversion (i.e. messages matching the regexp are discarded).
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.SH EXAMPLES
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Start a
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.IR sam (1)
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instance dedicated to editing kernel source code:
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.IP
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.EX
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ptrap edit '^/sys/src/9/'
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sam
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.EE
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.PP
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In another window, start a second
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.IR sam (1)
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instance for all other editing jobs:
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.IP
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.EX
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ptrap edit '!^/sys/src/9/'
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sam
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.EE
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.SH SOURCE
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.B /sys/src/cmd/ptrap.c
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.SH SEE ALSO
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.IR plumber (4),
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.IR plumb (6)
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.SH BUGS
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Multiple filters specified on the same port ignore all but the last one.
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.PP
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.I Ptrap
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would be more useful if it could inhibit sending the message to other clients.
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.PP
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As far as
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.IR plumber (4)
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is concerned, even messages dropped by
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.I ptrap
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are "accepted", which means rules that are supposed to apply to messages not accepted by clients are not invoked (e.g. a rule starting an editor if no one is listening to the
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.I edit
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port will not work if there is a
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.I ptrap
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on that port).
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.SH HISTORY
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.I Ptrap
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first appeared in 9front (February, 2018).
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375
sys/src/cmd/ptrap.c
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375
sys/src/cmd/ptrap.c
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@ -0,0 +1,375 @@
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#include <u.h>
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#include <libc.h>
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#include <thread.h>
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#include <fcall.h>
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#include <9p.h>
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#include <plumb.h>
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#include <regexp.h>
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typedef struct IOProc IOProc;
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typedef struct PFilter PFilter;
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typedef struct PFid PFid;
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struct IOProc {
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int id;
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Channel *ch;
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IOProc *next;
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};
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QLock freellock;
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IOProc *freel;
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struct PFid {
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char *name;
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PFilter *filter;
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int fd;
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char *msg;
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int msgn, msgp;
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};
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Qid rootqid = {.type QTDIR};
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struct PFilter {
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char *name;
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Reprog *filt;
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PFilter *next;
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int invert;
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};
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PFilter *filters;
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static char *
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fname(char *n)
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{
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static char *last;
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if(last != nil){
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free(last);
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last = nil;
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}
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if(n == nil)
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return "/mnt/plumb";
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last = smprint("/mnt/plumb/%s", n);
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return last;
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}
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static void theioproc(void *);
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static IOProc *
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getioproc(void)
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{
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IOProc *p;
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qlock(&freellock);
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p = freel;
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if(p != nil)
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freel = freel->next;
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qunlock(&freellock);
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if(p == nil){
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p = emalloc9p(sizeof(IOProc));
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p->ch = chancreate(sizeof(Req*), 0);
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p->id = proccreate(theioproc, p, 4096);
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}
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return p;
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}
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static void
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putioproc(IOProc *p)
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{
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qlock(&freellock);
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p->next = freel;
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freel = p;
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qunlock(&freellock);
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}
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static void
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ptrapattach(Req *r)
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{
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PFid *pf;
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pf = emalloc9p(sizeof(PFid));
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pf->fd = -1;
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r->fid->aux = pf;
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r->ofcall.qid = rootqid;
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r->fid->qid = rootqid;
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respond(r, nil);
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}
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static char *
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ptrapclone(Fid *old, Fid *new)
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{
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PFid *pf;
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pf = emalloc9p(sizeof(PFid));
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memcpy(pf, old->aux, sizeof(PFid));
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new->aux = pf;
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return nil;
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}
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static void
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ptrapdestroyfid(Fid *f)
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{
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PFid *pf;
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pf = f->aux;
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if(pf == nil) return;
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free(pf->name);
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if(pf->fd >= 0)
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close(pf->fd);
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free(pf);
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f->aux = nil;
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}
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static char *
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ptrapwalk1(Fid *fid, char *name, Qid *qid)
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{
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PFid *pf;
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Dir *d;
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static char err[ERRMAX];
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pf = fid->aux;
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if(pf->name != nil)
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return "phase error";
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d = dirstat(fname(name));
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if(d == nil){
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rerrstr(err, ERRMAX);
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return err;
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}
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pf->name = strdup(name);
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fid->qid = d->qid;
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*qid = d->qid;
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free(d);
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return nil;
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}
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static void
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ptrapopen(Req *r)
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{
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PFid* pf;
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PFilter *f;
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pf = r->fid->aux;
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pf->fd = open(fname(pf->name), r->ifcall.mode);
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if(pf->fd < 0){
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responderror(r);
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return;
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}
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if(pf->name == nil){
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respond(r, nil);
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return;
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}
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for(f = filters; f != nil; f = f->next)
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if(strcmp(f->name, pf->name) == 0)
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break;
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pf->filter = f;
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respond(r, nil);
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}
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static int
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filterread(Req *r, PFid *pf)
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{
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int rc, len, more;
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char *buf;
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Plumbmsg *pm;
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for(;;){
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if(pf->msg != nil){
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rc = r->ifcall.count;
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if(pf->msgp + rc >= pf->msgn)
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rc = pf->msgn - pf->msgp;
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r->ofcall.count = rc;
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memmove(r->ofcall.data, pf->msg + pf->msgp, rc);
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pf->msgp += rc;
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if(pf->msgp >= pf->msgn){
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free(pf->msg);
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pf->msg = nil;
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}
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return 0;
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}
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buf = emalloc9p(4096);
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rc = read(pf->fd, buf, 4096);
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if(rc < 0) goto err;
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len = rc;
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while(pm = plumbunpackpartial(buf, len, &more), pm == nil){
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if(more == 0) goto err;
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buf = erealloc9p(buf, len + more);
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rc = readn(pf->fd, buf + len, more);
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if(rc < 0) goto err;
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len += rc;
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}
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free(buf);
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if(regexec(pf->filter->filt, pm->data, nil, 0) ^ pf->filter->invert){
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pf->msg = plumbpack(pm, &pf->msgn);
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pf->msgp = 0;
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}
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plumbfree(pm);
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}
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err:
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free(buf);
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return -1;
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}
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static void
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theioproc(void *iopp)
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{
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Req *r;
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PFid *pf;
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IOProc *iop;
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char *buf;
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int fd, rc;
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rfork(RFNOTEG);
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buf = smprint("/proc/%d/ctl", getpid());
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fd = open(buf, OWRITE);
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free(buf);
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iop = iopp;
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for(;;){
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if(fd >= 0)
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write(fd, "nointerrupt", 11);
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r = recvp(iop->ch);
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r->aux = iop;
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pf = r->fid->aux;
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switch(r->ifcall.type){
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case Tread:
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if(!pf->filter){
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rc = pread(pf->fd, r->ofcall.data, r->ifcall.count, r->ifcall.offset);
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if(rc < 0){
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responderror(r);
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break;
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}
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r->ofcall.count = rc;
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respond(r, nil);
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break;
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}
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if(filterread(r, pf) < 0)
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responderror(r);
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else
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respond(r, nil);
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break;
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case Twrite:
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rc = pwrite(pf->fd, r->ifcall.data, r->ifcall.count, r->ifcall.offset);
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if(rc < 0)
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responderror(r);
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else{
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r->ofcall.count = rc;
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respond(r, nil);
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}
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break;
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}
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putioproc(iop);
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}
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}
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static void
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ptrapread(Req *r)
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{
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IOProc *iop;
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iop = getioproc();
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send(iop->ch, &r);
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}
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static void
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ptrapwrite(Req *r)
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{
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IOProc *iop;
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iop = getioproc();
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send(iop->ch, &r);
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}
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static void
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ptrapstat(Req *r)
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{
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PFid *pf;
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Dir *d;
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pf = r->fid->aux;
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if(pf->fd >= 0)
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d = dirfstat(pf->fd);
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else
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d = dirstat(fname(pf->name));
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if(d == nil){
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responderror(r);
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return;
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}
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memmove(&r->d, d, sizeof(Dir));
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r->d.name = strdup(d->name);
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r->d.uid = strdup(d->uid);
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r->d.muid = strdup(d->muid);
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r->d.gid = strdup(d->gid);
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free(d);
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respond(r, nil);
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}
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static void
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ptrapwstat(Req *r)
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{
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PFid *pf;
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int rc;
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pf = r->fid->aux;
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if(pf->fd >= 0)
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rc = dirfwstat(pf->fd, &r->d);
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else
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rc = dirwstat(fname(pf->name), &r->d);
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if(rc < 0)
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responderror(r);
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else
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respond(r, nil);
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}
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static void
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ptrapflush(Req *r)
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{
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if(r->oldreq->aux != nil)
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threadint(((IOProc*)r->oldreq->aux)->id);
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respond(r, nil);
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}
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Srv ptrapsrv = {
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.attach = ptrapattach,
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.clone = ptrapclone,
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.destroyfid = ptrapdestroyfid,
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.walk1 = ptrapwalk1,
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.open = ptrapopen,
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.read = ptrapread,
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.write = ptrapwrite,
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.stat = ptrapstat,
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.wstat = ptrapwstat,
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.flush = ptrapflush,
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};
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void
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usage(void)
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{
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fprint(2, "usage: %s port regex [ port regex ... ]\n", argv0);
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exits("usage");
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}
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void
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threadmain(int argc, char **argv)
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{
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PFilter *f;
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char *p;
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int i;
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ARGBEGIN{
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default: usage();
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}ARGEND;
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if(argc % 2) usage();
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for(i = 0; i < argc; i += 2){
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f = emalloc9p(sizeof(PFilter));
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f->name = strdup(argv[i]);
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p = argv[i+1];
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if(*p == '!'){
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p++;
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f->invert = 1;
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}
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f->filt = regcomp(p);
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if(f->filt == nil)
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sysfatal("%r");
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f->next = filters;
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filters = f;
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}
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threadpostmountsrv(&ptrapsrv, nil, "/mnt/plumb", MREPL | MCREATE);
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}
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