skel(3) → skelfs(4)
The original intention was to put devskel in to the kernel to detach what it provides from devsrv. That is not a good reason, just move it to userspace. auth/box has been changed to exec skelfs instead of relying on '#z'.
This commit is contained in:
Jacob Moody
parent
c7c0ff5db6
commit
c12022fd8c
7 changed files with 351 additions and 283 deletions
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@ -1,35 +0,0 @@
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.TH SKEL 3
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.SH NAME
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skel \- skeleton builder
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.SH SYNOPSIS
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.B bind #z/\fIskel\fR
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.I dir
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.PP
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.B bind #zd/\fIskel\fR
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.I dir
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.PP
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.B bind #ze/
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.I dir
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.SH DESCRIPTION
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.PP
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This device serves a single child directory with a single empty child
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file. The name of these files is determined by the first walk away
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from the root. After which, the hierarchy for that attached session
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becomes stable. The
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.B d
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attach option causes the child file to be an empty directory. The
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.B e
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attach option presents a completly empty root directory.
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.SH EXAMPLES
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Skeleton files can be used for constructing arbitrary bind targets.
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.EX
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.IP
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bind -b '#zd/newroot' /
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bind '#zd/bin' /newroot
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bind '#z/walk' /newroot/bin
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bind /bin/walk /newroot/bin/walk
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bind /newroot /
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walk /
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.EE
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.SH SOURCE
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.B /sys/src/9/port/devskel.c
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65
sys/man/4/skelfs
Normal file
65
sys/man/4/skelfs
Normal file
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@ -0,0 +1,65 @@
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.TH SKELFS 4
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.SH NAME
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skelfs \- build directory skeletons
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.SH SYNOPSIS
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.B skelfs
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[
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.B -i
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]
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[
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.B -t
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.I mode
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]
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[
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.B -s
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.I service
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]
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[
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.I mnt
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]
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.SH DESCRIPTION
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.I Skelfs
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generates directory skeletons
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to assist in building namespaces.
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Skeletons are generated on demand
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by walking through the root directory.
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A skeleon is a directory containing a single empty child.
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The name of this child is defined by the first walk taken
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away from the root. For example the hierarchy for a skeleton
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named 'echo' would be:
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.PP
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.EX
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/
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/echo/
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/echo/echo
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.EE
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.PP
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The
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.I mode
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dictates what form the innermost child file takes. The
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.B file
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and
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.B dir
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modes cause the child to be an empty file or directory
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respecively. The
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.B empty
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mode instead serves no skeletons, causing the root
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directory to always be empty.
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A client may override the mode by providing
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its own selection as an attach option. If a
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mode is not provided,
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.B file
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is assumed.
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.PP
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The skeletons generated by
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.I skelfs
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are anonmyous. Clients will never see the
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skeletons of other clients, nor can a client revisit
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a previous skeleton.
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.PP
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.SH "SEE ALSO"
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.B auth/box
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in
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.IR auth (8).
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.SH SOURCE
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.B /sys/src/cmd/skelfs.c
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@ -18,7 +18,6 @@ dev
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kprof
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fs
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dtracy
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skel
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ether netif
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bridge netif log
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@ -41,7 +41,6 @@ dev
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segment
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vmx
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dtracy
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skel
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link
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# devpccard pci
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@ -1,239 +0,0 @@
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#include "u.h"
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#include "../port/lib.h"
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#include "mem.h"
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#include "dat.h"
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#include "fns.h"
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#include "../port/error.h"
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#include "netif.h"
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typedef struct Skel Skel;
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struct Skel {
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RWlock;
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int ref;
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char name[KNAMELEN];
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char mode;
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};
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struct
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{
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QLock;
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ulong path;
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} skelalloc;
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enum{
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Qroot,
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Qdir,
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Qskel,
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};
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static Chan*
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skelattach(char *spec)
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{
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Chan *c;
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Skel *f;
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uvlong path;
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c = devattach('z', spec);
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f = mallocz(sizeof *f, 1);
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if(f == nil)
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exhausted("memory");
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if(waserror()){
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free(f);
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nexterror();
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}
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if(spec == nil)
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f->mode = 'f';
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else
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f->mode = spec[0];
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eqlock(&skelalloc);
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path = skelalloc.path++;
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qunlock(&skelalloc);
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poperror();
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mkqid(&c->qid, NETQID(path, Qroot), path, QTDIR);
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f->ref = 1;
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c->aux = f;
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return c;
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}
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static int
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step(Chan *c, Dir *dp, int direction)
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{
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Skel *f;
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Qid qid;
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ulong perm;
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int path;
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char *name;
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perm = 0555|DMDIR;
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path = NETTYPE(c->qid.path);
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f = c->aux;
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rlock(f);
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if(waserror()){
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runlock(f);
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return -1;
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}
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name = f->name;
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path += direction;
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if(!f->name[0] && path > Qroot)
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error(Enonexist);
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switch(path){
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case Qroot-1:
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case Qroot:
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mkqid(&qid, Qroot, 0, QTDIR);
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name = "#z";
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break;
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case Qdir:
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mkqid(&qid, Qdir, 0, QTDIR);
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break;
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case Qskel:
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switch(f->mode){
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case 'd':
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mkqid(&qid, Qskel, 0, QTDIR);
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break;
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case 'f':
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default:
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mkqid(&qid, Qskel, 0, QTFILE);
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perm = 0666;
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break;
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}
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break;
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default:
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error(Enonexist);
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}
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qid.vers = NETID(c->qid.path);
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qid.path = NETQID(qid.vers, qid.path);
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devdir(c, qid, name, 0, eve, perm, dp);
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runlock(f);
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poperror();
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return 1;
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}
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static int
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skelgen(Chan *c, char *name, Dirtab*, int, int s, Dir *dp)
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{
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Skel *f;
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switch(s){
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case DEVDOTDOT:
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break;
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case 0:
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s++;
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break;
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default:
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return -1;
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}
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f = c->aux;
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if(name && NETTYPE(c->qid.path) == Qroot){
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wlock(f);
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if(!f->name[0] && f->mode != 'e')
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utfecpy(f->name, &f->name[sizeof f->name-1], name);
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wunlock(f);
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}
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return step(c, dp, s);
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}
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static Walkqid*
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skelwalk(Chan *c, Chan *nc, char **name, int nname)
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{
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Walkqid *wq;
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Skel *f;
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wq = devwalk(c, nc, name, nname, nil, 0, skelgen);
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if(wq == nil || wq->clone == nil)
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return wq;
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f = c->aux;
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wlock(f);
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if(f->ref <= 0)
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panic("devskel ref");
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f->ref++;
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wunlock(f);
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return wq;
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}
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static Chan*
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skelopen(Chan *c, int omode)
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{
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if(!(c->qid.type & QTDIR))
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error(Eperm);
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if(omode != OREAD)
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error(Ebadarg);
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c->mode = omode;
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c->flag |= COPEN;
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c->offset = 0;
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return c;
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}
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static void
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skelclose(Chan *c)
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{
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Skel *f;
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f = c->aux;
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wlock(f);
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f->ref--;
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if(f->ref == 0){
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wunlock(f);
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free(f);
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} else
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wunlock(f);
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}
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static long
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skelread(Chan *c, void *va, long n, vlong)
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{
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return devdirread(c, va, n, nil, 0, skelgen);
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}
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static long
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skelwrite(Chan*, void*, long, vlong)
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{
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error(Ebadusefd);
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return -1;
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}
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static int
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skelstat(Chan *c, uchar *db, int n)
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{
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Dir dir;
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if(step(c, &dir, 0) < 0)
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error(Enonexist);
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n = convD2M(&dir, db, n);
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if(n < BIT16SZ)
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error(Eshortstat);
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return n;
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}
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Dev skeldevtab = {
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'z',
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"skel",
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devreset,
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devinit,
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devshutdown,
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skelattach,
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skelwalk,
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skelstat,
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skelopen,
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devcreate,
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skelclose,
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skelread,
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devbread,
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skelwrite,
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devbwrite,
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devremove,
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devwstat,
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};
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@ -29,7 +29,7 @@ binderr(char *new, char *old, int flag)
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dash[1] = 'a';
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break;
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}
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print("bind %s %s %s\n", dash, new, old);
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fprint(2, "bind %s %s %s\n", dash, new, old);
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}
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if(bind(new, old, flag) < 0)
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sysfatal("bind: %r");
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@ -72,10 +72,10 @@ sandbox(char **names, int *flags, int nname)
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Dir *d;
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int i, j, n;
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snprint(rootskel, sizeof rootskel, "#zd/newroot.%d", getpid());
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snprint(rootskel, sizeof rootskel, "/mnt/d/newroot.%d", getpid());
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binderr(rootskel, "/", MBEFORE);
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newroot = rootskel + strlen("#zd");
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newroot = rootskel + strlen("/mnt/d");
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for(j = 0; j < nname; j++){
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if(names[j] == nil)
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@ -97,9 +97,9 @@ sandbox(char **names, int *flags, int nname)
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if(d == nil)
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continue;
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if(d->mode & DMDIR)
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snprint(skel, sizeof skel, "#zd/%s", parts[i]);
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snprint(skel, sizeof skel, "/mnt/d/%s", parts[i]);
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else
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snprint(skel, sizeof skel, "#zf/%s", parts[i]);
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snprint(skel, sizeof skel, "/mnt/f/%s", parts[i]);
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free(d);
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binderr(skel, dir, MBEFORE);
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}
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@ -108,6 +108,31 @@ sandbox(char **names, int *flags, int nname)
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binderr(newroot, "/", MREPL);
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}
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void
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skelfs(void)
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{
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int p[2];
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int dfd;
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pipe(p);
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switch(rfork(RFFDG|RFREND|RFPROC|RFNAMEG)){
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case -1:
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sysfatal("fork");
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case 0:
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close(p[1]);
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dup(p[0], 0);
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dup(p[0], 1);
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execl("/bin/skelfs", "skelfs", debug > 1 ? "-Di" : "-i", nil);
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sysfatal("exec /bin/skelfs: %r");
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}
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close(p[0]);
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dfd = dup(p[1], -1);
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if(mount(p[1], -1, "/mnt/f", MREPL, "file") < 0)
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sysfatal("/mnt/f mount setup: %r");
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if(mount(dfd, -1, "/mnt/d", MREPL, "dir") < 0)
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sysfatal("/mnt/d mount setup: %r");
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}
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void
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usage(void)
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{
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@ -129,8 +154,10 @@ main(int argc, char **argv)
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nparts = 0;
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memset(devs, 0, sizeof devs);
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ARGBEGIN{
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case 'D':
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debug++;
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case 'd':
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debug = 1;
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debug++;
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break;
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case 'r':
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parts[nparts] = EARGF(usage());
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@ -164,6 +191,7 @@ main(int argc, char **argv)
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argv[0] = b;
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rfork(RFNAMEG|RFFDG);
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skelfs();
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dfd = open("/dev/drivers", OWRITE|OCEXEC);
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if(dfd < 0)
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sysfatal("could not /dev/drivers: %r");
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@ -172,7 +200,7 @@ main(int argc, char **argv)
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sandbox(parts, mflags, nparts);
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if(debug)
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print("chdev %s\n", devs);
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fprint(2, "chdev %s\n", devs);
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if(devs[0] != '\0'){
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if(fprint(dfd, "chdev & %s", devs) <= 0)
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|
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251
sys/src/cmd/skelfs.c
Normal file
251
sys/src/cmd/skelfs.c
Normal file
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@ -0,0 +1,251 @@
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#include <u.h>
|
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#include <libc.h>
|
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#include <fcall.h>
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#include <thread.h>
|
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#include <9p.h>
|
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|
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typedef struct Skel Skel;
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struct Skel {
|
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char name[64];
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char mode;
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};
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|
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static uvlong sessions;
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static char defmode;
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enum{
|
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Qroot,
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Qdir,
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Qskel,
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};
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|
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#define qtype(x) (((ulong)x)&0x1f)
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#define qsess(x) ((((ulong)x))>>5)
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#define mkqid(i,t) ((((ulong)i)<<5)|(t))
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|
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static int
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step(Fid *f, int way, Qid *res, Dir *dp)
|
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{
|
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Skel *s;
|
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int path;
|
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char *name;
|
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ulong perm;
|
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|
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s = f->aux;
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name = s->name;
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perm = 0550|DMDIR;
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path = qtype(f->qid.path) + way;
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if(!name[0] && way > 0)
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return -1;
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|
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if(path < 0)
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goto Root;
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switch(path){
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Root:
|
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case Qroot:
|
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name = "/";
|
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/* fallthrough */
|
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case Qdir:
|
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res->type = QTDIR;
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break;
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case Qskel:
|
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switch(s->mode){
|
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case 'd':
|
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res->type = QTDIR;
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break;
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case 'f':
|
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default:
|
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res->type = QTFILE;
|
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perm = 0;
|
||||
break;
|
||||
}
|
||||
break;
|
||||
default:
|
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return -1;
|
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}
|
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res->vers = qsess(f->qid.path);
|
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res->path = mkqid(res->vers, path);
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if(dp){
|
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dp->mode = perm;
|
||||
dp->name = estrdup9p(name);
|
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dp->uid = estrdup9p("sys");
|
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dp->gid = estrdup9p("sys");
|
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dp->qid = *res;
|
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dp->length = 0;
|
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}
|
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return 1;
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}
|
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|
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static int
|
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dirgen(int i, Dir *d, void *a)
|
||||
{
|
||||
Fid *f;
|
||||
Qid q;
|
||||
|
||||
if(i > 0)
|
||||
return -1;
|
||||
f = a;
|
||||
return step(f, 1, &q, d);
|
||||
}
|
||||
|
||||
static void
|
||||
fidclunk(Fid *fid)
|
||||
{
|
||||
free(fid->aux);
|
||||
}
|
||||
|
||||
static char*
|
||||
fsclone(Fid *old, Fid *new, void*)
|
||||
{
|
||||
Skel *s, *s2;
|
||||
|
||||
s = old->aux;
|
||||
s2 = emalloc9p(sizeof *s2);
|
||||
if(s2 == nil)
|
||||
return "out of memory";
|
||||
memset(s2, 0, sizeof *s2);
|
||||
|
||||
s2->mode = s->mode;
|
||||
utfecpy(s2->name, &s2->name[sizeof s2->name-1], s->name);
|
||||
new->aux = s2;
|
||||
return nil;
|
||||
}
|
||||
|
||||
static char*
|
||||
fswalk1(Fid *old, char *name, void*)
|
||||
{
|
||||
Skel *s;
|
||||
|
||||
if(strcmp("..", name) == 0){
|
||||
step(old, -1, &old->qid, nil);
|
||||
return nil;
|
||||
}
|
||||
|
||||
s = old->aux;
|
||||
if(!s->name[0] && qtype(old->qid.path) == Qroot && s->mode != 'e'){
|
||||
utfecpy(s->name, &s->name[sizeof s->name-1], name);
|
||||
old->qid.vers = sessions++;
|
||||
old->qid.path = mkqid(old->qid.vers, qtype(old->qid.path));
|
||||
} else if(strcmp(name, s->name) != 0)
|
||||
return "does not exist";
|
||||
|
||||
if(step(old, 1, &old->qid, nil) < 0)
|
||||
return "does not exist";
|
||||
|
||||
return nil;
|
||||
}
|
||||
|
||||
static void
|
||||
fswalk(Req *r)
|
||||
{
|
||||
walkandclone(r, fswalk1, fsclone, nil);
|
||||
}
|
||||
|
||||
static void
|
||||
fsattach(Req *r)
|
||||
{
|
||||
Skel s;
|
||||
Fid root;
|
||||
char *spec;
|
||||
Qid *q;
|
||||
|
||||
spec = r->ifcall.aname;
|
||||
if(spec && spec[0] != '\0')
|
||||
s.mode = spec[0];
|
||||
else
|
||||
s.mode = defmode;
|
||||
|
||||
q = &r->fid->qid;
|
||||
q->vers = sessions++;
|
||||
q->path = mkqid(q->vers, Qroot);
|
||||
q->type = QTDIR;
|
||||
r->ofcall.qid = *q;
|
||||
|
||||
s.name[0] = '\0';
|
||||
root.aux = &s;
|
||||
respond(r, fsclone(&root, r->fid, nil));
|
||||
}
|
||||
|
||||
static void
|
||||
fsstat(Req *r)
|
||||
{
|
||||
Qid q;
|
||||
|
||||
if(step(r->fid, 0, &q, &r->d) < 0)
|
||||
respond(r, "does not exist");
|
||||
respond(r, nil);
|
||||
}
|
||||
|
||||
static void
|
||||
fsread(Req *r)
|
||||
{
|
||||
dirread9p(r, dirgen, r->fid);
|
||||
respond(r, nil);
|
||||
}
|
||||
|
||||
static void
|
||||
fsopen(Req *r)
|
||||
{
|
||||
r->ofcall.mode = r->ifcall.mode;
|
||||
if(r->ifcall.mode != OREAD)
|
||||
respond(r, "permission denied");
|
||||
else
|
||||
respond(r, nil);
|
||||
}
|
||||
|
||||
Srv fs=
|
||||
{
|
||||
.attach= fsattach,
|
||||
.open= fsopen,
|
||||
.read= fsread,
|
||||
.stat= fsstat,
|
||||
.walk= fswalk,
|
||||
.destroyfid= fidclunk
|
||||
};
|
||||
|
||||
void
|
||||
usage(void)
|
||||
{
|
||||
fprint(2, "usage: %s [ -Di ] [ -s service ] [ -t mode ] [ mntpt ]\n", argv0);
|
||||
exits("usage");
|
||||
}
|
||||
|
||||
void
|
||||
main(int argc, char **argv)
|
||||
{
|
||||
char *s, *mode;
|
||||
int stdio;
|
||||
|
||||
s = nil;
|
||||
stdio = 0;
|
||||
defmode = 'f';
|
||||
ARGBEGIN{
|
||||
case 'D':
|
||||
chatty9p++;
|
||||
break;
|
||||
case 's':
|
||||
s = EARGF(usage());
|
||||
break;
|
||||
case 'i':
|
||||
stdio = 1;
|
||||
break;
|
||||
case 't':
|
||||
mode = EARGF(usage());
|
||||
defmode = mode[0];
|
||||
break;
|
||||
default:
|
||||
usage();
|
||||
}ARGEND
|
||||
|
||||
if(argc > 1)
|
||||
usage();
|
||||
|
||||
if(stdio == 0){
|
||||
postmountsrv(&fs, s, argc ? argv[0] : "/mnt/skel", MREPL);
|
||||
exits(nil);
|
||||
}
|
||||
fs.infd = 0;
|
||||
fs.outfd = 1;
|
||||
srv(&fs);
|
||||
exits(nil);
|
||||
}
|
||||
Loading…
Reference in a new issue