ref: f4840cdba548979969cb2ad25b4c6acbc3e63f8c
parent: df92301d8fc8310fbfdf3de91b97a156ca0504d4
author: Jacob Moody <[email protected]>
date: Tue Jun 7 01:25:44 EDT 2022
kernel: add devskel for pc and pc64
--- /dev/null
+++ b/sys/man/3/skel
@@ -1,0 +1,35 @@
+.TH SKEL 3
+.SH NAME
+skel \- skeleton builder
+.SH SYNOPSIS
+.B bind #z/\fIskel\fR
+.I dir
+.PP
+.B bind #zd/\fIskel\fR
+.I dir
+.PP
+.B bind #ze/
+.I dir
+.SH DESCRIPTION
+.PP
+This device serves a single child directory with a single empty child
+file. The name of these files is determined by the first walk away
+from the root. After which, the hierarchy for that attached session
+becomes stable. The
+.B d
+attach option causes the child file to be an empty directory. The
+.B e
+attach option presents a completly empty root directory.
+.SH EXAMPLES
+Skeleton files can be used for constructing arbitrary bind targets.
+.EX
+.IP
+bind -b '#zd/newroot' /
+bind '#zd/bin' /newroot
+bind '#z/walk' /newroot/bin
+bind /bin/walk /newroot/bin/walk
+bind /newroot /
+walk /
+.EE
+.SH SOURCE
+.B /sys/src/9/port/devskel.c
--- a/sys/src/9/pc/pc
+++ b/sys/src/9/pc/pc
@@ -18,6 +18,7 @@
kprof
fs
dtracy
+ skel
ether netif
bridge netif log
--- a/sys/src/9/pc64/pc64
+++ b/sys/src/9/pc64/pc64
@@ -41,6 +41,7 @@
segment
vmx
dtracy
+ skel
link
# devpccard pci
--- /dev/null
+++ b/sys/src/9/port/devskel.c
@@ -1,0 +1,237 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "../port/error.h"
+
+#include "netif.h"
+
+typedef struct Skel Skel;
+struct Skel {+ int ref;
+ QLock lk;
+ char name[KNAMELEN];
+ char mode;
+};
+
+struct
+{+ QLock lk;
+ ulong path;
+} skelalloc;
+
+enum{+ Qroot,
+ Qdir,
+ Qskel,
+};
+
+static Chan*
+skelattach(char *spec)
+{+ Chan *c;
+ Skel *f;
+ uvlong path;
+
+ c = devattach('z', spec);+
+ f = smalloc(sizeof *f);
+ if(spec != nil && spec[0] != '\0' && strchr("de", spec[0]) != nil)+ f->mode = spec[0];
+ else
+ f->mode = 'f';
+
+ f->ref = 1;
+
+ qlock(&skelalloc.lk);
+ path = skelalloc.path++;
+ qunlock(&skelalloc.lk);
+
+ mkqid(&c->qid, NETQID(path, Qroot), 0, QTDIR);
+ c->aux = f;
+ return c;
+}
+
+static int
+step(Chan *c, Dir *dp, int direction)
+{+ Skel *f;
+ Qid qid;
+ ulong perm;
+ uvlong path;
+ char *name;
+
+ perm = 0555|DMDIR;
+ path = NETTYPE(c->qid.path);
+ f = c->aux;
+ name = f->name;
+
+ path += direction;
+ if(!f->name[0] && path != Qroot)
+ return -1;
+
+ switch(path){+ case Qroot:
+ mkqid(&qid, Qroot, 0, QTDIR);
+ name = "#z";
+ break;
+ case Qdir:
+ mkqid(&qid, Qdir, 0, QTDIR);
+ break;
+ case Qskel:
+ switch(f->mode){+ case 'd':
+ mkqid(&qid, Qskel, 0, QTDIR);
+ break;
+ case 'f':
+ default:
+ mkqid(&qid, Qskel, 0, QTFILE);
+ perm = 0666;
+ break;
+ }
+ break;
+ default:
+ return -1;
+ }
+
+ qid.path = NETQID(NETID(c->qid.path), qid.path);
+ devdir(c, qid, name, 0, eve, perm, dp);
+ return 1;
+}
+
+
+static int
+skelgen(Chan *c, char *name, Dirtab *, int, int s, Dir *dp)
+{+ Skel *f;
+
+ f = c->aux;
+ //First walk away from root
+ if(name && !f->name[0] && f->mode != 'e' && NETTYPE(c->qid.path) == Qroot)
+ utfecpy(f->name, &f->name[sizeof f->name-1], name);
+
+ if(s != DEVDOTDOT)
+ s++;
+
+ return step(c, dp, s);
+}
+
+static Walkqid*
+skelwalk(Chan *c, Chan *nc, char **name, int nname)
+{+ Walkqid *wq;
+ Skel *f;
+
+ f = c->aux;
+ qlock(&f->lk);
+ if(waserror()){+ qunlock(&f->lk);
+ nexterror();
+ }
+
+ wq = devwalk(c, nc, name, nname, nil, 0, skelgen);
+ if(wq != nil && wq->clone != nil && wq->clone != c){+ if(f->ref <= 0)
+ panic("devskel ref");+ f->ref++;
+ }
+ qunlock(&f->lk);
+ poperror();
+ return wq;
+}
+
+static Chan*
+skelopen(Chan *c, int omode)
+{+ if(!(c->qid.type & QTDIR))
+ error(Eperm);
+ if(omode != OREAD)
+ error(Ebadarg);
+
+ c->mode = omode;
+ c->flag |= COPEN;
+ c->offset = 0;
+ return c;
+}
+
+static void
+skelclose(Chan *c)
+{+ Skel *f;
+
+ f = c->aux;
+ qlock(&f->lk);
+ f->ref--;
+ if(f->ref == 0){+ qunlock(&f->lk);
+ free(f);
+ } else
+ qunlock(&f->lk);
+}
+
+static long
+skelread(Chan *c, void *va, long n, vlong)
+{+ Skel *f;
+ long nout;
+
+ if(!(c->qid.type & QTDIR))
+ error(Eperm);
+
+ f = c->aux;
+ qlock(&f->lk);
+ if(waserror()){+ qunlock(&f->lk);
+ nexterror();
+ }
+ nout = devdirread(c, va, n, nil, 0, skelgen);
+ qunlock(&f->lk);
+ poperror();
+ return nout;
+}
+
+static long
+skelwrite(Chan *, void *, long, vlong)
+{+ error(Eperm);
+ return 0;
+}
+
+static int
+skelstat(Chan *c, uchar *db, int n)
+{+ Skel *f;
+ Dir dir;
+
+ f = c->aux;
+ qlock(&f->lk);
+ step(c, &dir, 0);
+ qunlock(&f->lk);
+
+ n = convD2M(&dir, db, n);
+ if(n < BIT16SZ)
+ error(Eshortstat);
+ return n;
+}
+
+Dev skeldevtab = {+ 'z',
+ "skel",
+
+ devreset,
+ devinit,
+ devshutdown,
+ skelattach,
+ skelwalk,
+ skelstat,
+ skelopen,
+ devcreate,
+ skelclose,
+ skelread,
+ devbread,
+ skelwrite,
+ devbwrite,
+ devremove,
+ devwstat,
+};