2 #include "../port/lib.h"
6 #include "../port/error.h"
8 int chandebug=0; /* toggled by sysr1 */
9 #define DBG if(chandebug)iprint
17 static struct Chanalloc
25 typedef struct Elemlist Elemlist;
29 char *aname; /* original name */
30 char *name; /* copy of name, so '/' can be overwritten */
39 #define SEP(c) ((c) == 0 || (c) == '/')
42 dumpmount(void) /* DEBUGGING */
49 print("no process for dumpmount\n");
54 print("no pgrp for dumpmount\n");
63 he = &pg->mnthash[MNTHASH];
64 for(h = pg->mnthash; h < he; h++){
65 for(f = *h; f; f = f->hash){
66 print("head: %#p: %s %#llux.%lud %C %lud -> \n", f,
67 f->from->path->s, f->from->qid.path,
68 f->from->qid.vers, devtab[f->from->type]->dc,
70 for(t = f->mount; t; t = t->next)
71 print("\t%#p: %s (umh %#p) (path %#.8llux dev %C %lud)\n", t, t->to->path->s, t->to->umh, t->to->qid.path, devtab[t->to->type]->dc, t->to->dev);
86 return "<nil path.s>";
93 return p[0]=='.' && p[1]=='.' && p[2]=='\0';
116 panic("decref pc=%#p", getcallerpc(&r));
121 * Rather than strncpy, which zeros the rest of the buffer, kstrcpy
122 * truncates if necessary, always zero terminates, does not zero fill,
123 * and puts ... at the end of the string if it's too long. Usually used to
124 * save a string in up->genbuf;
127 kstrcpy(char *s, char *t, int ns)
137 /* too long, truncate */
141 /* append ... if there is space */
145 /* look for first byte of UTF-8 sequence by skipping continuation bytes */
146 while(ns>0 && (s[--ns]&0xC0)==0x80)
162 * Atomically replace *p with copy of s
165 kstrdup(char **p, char *s)
171 /* if it's a user, we can wait for memory; if not, something's very wrong */
177 panic("kstrdup: no memory");
179 setmalloctag(t, getcallerpc(&p));
192 todinit(); /* avoid later reentry causing infinite recursion */
193 for(i=0; devtab[i] != nil; i++)
202 for(i=0; devtab[i] != nil; i++)
207 chandevshutdown(void)
211 /* shutdown in reverse order */
212 for(i=0; devtab[i] != nil; i++)
214 for(i--; i >= 0; i--)
215 devtab[i]->shutdown();
226 chanalloc.free = c->next;
232 c = smalloc(sizeof(Chan));
234 c->fid = ++chanalloc.fid;
235 c->link = chanalloc.list;
240 /* if you get an error before associating with a dev,
241 close calls rootclose, a nop */
256 memset(&c->mqid, 0, sizeof(c->mqid));
271 p = smalloc(sizeof(Path));
274 p->alen = i+PATHSLOP;
275 p->s = smalloc(p->alen);
276 memmove(p->s, s, i+1);
281 * Cannot use newpath for arbitrary names because the mtpt
282 * array will not be populated correctly. The names #/ and / are
283 * allowed, but other names with / in them draw warnings.
285 if(strchr(s, '/') && strcmp(s, "#/") != 0 && strcmp(s, "/") != 0)
286 print("newpath: %s from %#p\n", s, getcallerpc(&s));
289 p->malen = PATHMSLOP;
290 p->mtpt = smalloc(p->malen*sizeof p->mtpt[0]);
300 pp = smalloc(sizeof(Path));
303 DBG("copypath %s %p => %p\n", p->s, p, pp);
307 pp->s = smalloc(p->alen);
308 memmove(pp->s, p->s, p->len+1);
311 pp->malen = p->malen;
312 pp->mtpt = smalloc(p->malen*sizeof pp->mtpt[0]);
313 for(i=0; i<pp->mlen; i++){
314 pp->mtpt[i] = p->mtpt[i];
330 DBG("pathclose %p %s ref=%ld =>", p, p->s, p->ref);
331 for(i=0; i<p->mlen; i++)
332 DBG(" %p", p->mtpt[i]);
339 for(i=0; i<p->mlen; i++)
347 * In place, rewrite name to compress multiple /, eliminate ., and process ..
348 * (Really only called to remove a trailing .. that has been added.
349 * Otherwise would need to update n->mtpt as well.)
352 fixdotdotname(Path *p)
357 r = strchr(p->s, '/');
363 * The correct name is #i rather than #i/,
364 * but the correct name of #/ is #/.
366 if(strcmp(r, "/")==0 && p->s[1] != '/')
370 p->len = strlen(p->s);
388 addelem(Path *p, char *s, Chan *from)
394 if(s[0]=='.' && s[1]=='\0')
400 if(p->len+1+i+1 > p->alen){
401 a = p->len+1+i+1 + PATHSLOP;
403 memmove(t, p->s, p->len+1);
408 /* don't insert extra slash if one is present */
409 if(p->len>0 && p->s[p->len-1]!='/' && s[0]!='/')
410 p->s[p->len++] = '/';
411 memmove(p->s+p->len, s, i+1);
415 DBG("addelem %s .. => rm %p\n", p->s, p->mtpt[p->mlen-1]);
416 if(p->mlen>1 && (c = p->mtpt[--p->mlen])){
417 p->mtpt[p->mlen] = nil;
421 if(p->mlen >= p->malen){
422 p->malen = p->mlen+1+PATHMSLOP;
423 tt = smalloc(p->malen*sizeof tt[0]);
424 memmove(tt, p->mtpt, p->mlen*sizeof tt[0]);
428 DBG("addelem %s %s => add %p\n", p->s, s, from);
429 p->mtpt[p->mlen++] = from;
441 if(c->dirrock != nil){
468 c->next = chanalloc.free;
474 * Queue a chan to be closed by one of the clunk procs.
489 return clunkq.head != nil;
498 if(clunkq.head == nil){
500 tsleep(&clunkq.r, clunkwork, nil, 5000);
511 clunkq.head = c->next;
515 devtab[c->type]->close(c);
530 clunkq.tail->next = c;
536 if(up != 0 && palloc.Lock.p != up && canqlock(&clunkq.q)){
540 kproc("closeproc", closeproc, nil);
551 if(c == nil || c->ref < 1 || c->flag&CFREE)
552 panic("cclose %#p", getcallerpc(&c));
554 DBG("cclose %p name=%s ref=%ld\n", c, chanpath(c), c->ref);
559 if(devtab[c->type]->dc == L'M')
560 if((c->flag&(CRCLOSE|CCACHE)) == CCACHE)
561 if((c->qid.type&(QTEXCL|QTMOUNT|QTAUTH)) == 0)
562 if((clunkq.nqueued - clunkq.nclosed) < 64){
568 devtab[c->type]->close(c);
577 if(c == nil || c->ref < 1 || c->flag&CFREE)
578 panic("ccloseq %#p", getcallerpc(&c));
580 DBG("ccloseq %p name=%s ref=%ld\n", c, chanpath(c), c->ref);
589 * Make sure we have the only copy of c. (Copy on write.)
608 return a.path==b.path && a.vers==b.vers;
612 eqchan(Chan *a, Chan *b, int skipvers)
614 if(a->qid.path != b->qid.path)
616 if(!skipvers && a->qid.vers!=b->qid.vers)
618 if(a->type != b->type)
626 eqchantdqid(Chan *a, int type, int dev, Qid qid, int skipvers)
628 if(a->qid.path != qid.path)
630 if(!skipvers && a->qid.vers!=qid.vers)
644 mh = smalloc(sizeof(Mhead));
652 cmount(Chan **newp, Chan *old, int flag, char *spec)
657 Mount *nm, *f, *um, **h;
660 if(QTDIR & (old->qid.type^(*newp)->qid.type))
664 print("cmount: unexpected umh, caller %#p\n", getcallerpc(&newp));
668 if((old->qid.type&QTDIR)==0 && order != MREPL)
675 * Not allowed to bind when the old directory is itself a union.
676 * (Maybe it should be allowed, but I don't see what the semantics
679 * We need to check mh->mount->next to tell unions apart from
680 * simple mount points, so that things like
685 * The check of mount->mflag allows things like
689 * This is far more complicated than it should be, but I don't
690 * see an easier way at the moment.
692 if((flag&MCREATE) && mh && mh->mount
693 && (mh->mount->next || !(mh->mount->mflag&MCREATE)))
699 l = &MOUNTH(pg, old->qid);
700 for(m = *l; m; m = m->hash){
701 if(eqchan(m->from, old, 1))
708 * nothing mounted here yet. create a mount
709 * head and add to the hash table.
715 * if this is a union mount, add the old
716 * node to the mount chain.
719 m->mount = newmount(m, old, 0, 0);
728 nm = newmount(m, new, flag, spec);
729 if(mh != nil && mh->mount != nil){
731 * copy a union when binding it onto a directory
738 for(um = um->next; um; um = um->next){
739 f = newmount(m, um->to, flg, um->spec);
745 if(m->mount && order == MREPL){
751 nm->mflag |= MCREATE;
753 if(m->mount && order == MAFTER){
754 for(f = m->mount; f->next; f = f->next)
758 for(f = nm; f->next; f = f->next)
770 cunmount(Chan *mnt, Chan *mounted)
776 if(mnt->umh) /* should not happen */
777 print("cunmount newp extra umh %p has %p\n", mnt, mnt->umh);
780 * It _can_ happen that mounted->umh is non-nil,
781 * because mounted is the result of namec(Aopen)
782 * (see sysfile.c:/^sysunmount).
783 * If we open a union directory, it will have a umh.
784 * Although surprising, this is okay, since the
785 * cclose will take care of freeing the umh.
791 l = &MOUNTH(pg, mnt->qid);
792 for(m = *l; m; m = m->hash){
793 if(eqchan(m->from, mnt, 1))
816 for(f = *p; f; f = f->next){
817 /* BUG: Needs to be 2 pass */
818 if(eqchan(f->to, mounted, 1) ||
819 (f->to->mchan && eqchan(f->to->mchan, mounted, 1))){
848 if(c == nil || c->ref < 1 || c->flag&CFREE)
849 panic("cclone: %#p", getcallerpc(&c));
850 wq = devtab[c->type]->walk(c, nil, nil, 0);
852 error("clone failed");
861 /* also used by sysfile.c:/^mountfix */
863 findmount(Chan **cp, Mhead **mp, int type, int dev, Qid qid)
870 for(m = MOUNTH(pg, qid); m; m = m->hash){
873 print("m %p m->from 0\n", m);
877 if(eqchantdqid(m->from, type, dev, qid, 1)){
887 incref(m->mount->to);
900 * Calls findmount but also updates path.
903 domount(Chan **cp, Mhead **mp, Path **path)
908 if(findmount(cp, mp, (*cp)->type, (*cp)->dev, (*cp)->qid) == 0)
915 print("domount: path %s has mlen==%d\n", p->s, p->mlen);
917 lc = &p->mtpt[p->mlen-1];
918 DBG("domount %p %s => add %p (was %p)\n", p, p->s, (*mp)->from, p->mtpt[p->mlen-1]);
930 * If c is the right-hand-side of a mount point, returns the left hand side.
931 * Changes name to reflect the fact that we've uncrossed the mountpoint,
932 * so name had better be ours to change!
935 undomount(Chan *c, Path *path)
939 if(path->ref != 1 || path->mlen == 0)
940 print("undomount: path %s ref %ld mlen %d caller %#p\n",
941 path->s, path->ref, path->mlen, getcallerpc(&c));
943 if(path->mlen>0 && (nc=path->mtpt[path->mlen-1]) != nil){
944 DBG("undomount %p %s => remove %p\n", path, path->s, nc);
946 path->mtpt[path->mlen-1] = nil;
953 * Call dev walk but catch errors.
956 ewalk(Chan *c, Chan *nc, char **name, int nname)
962 wq = devtab[c->type]->walk(c, nc, name, nname);
968 * Either walks all the way or not at all. No partial results in *cp.
969 * *nerror is the number of names to display in an error message.
971 static char Edoesnotexist[] = "does not exist";
973 walk(Chan **cp, char **names, int nnames, int nomount, int *nerror)
975 int dev, didmount, dotdot, i, n, nhave, ntry, type;
989 * While we haven't gotten all the way down the path:
990 * 1. step through a mount point, if any
991 * 2. send a walk request for initial dotdot or initial prefix without dotdot
992 * 3. move to the first mountpoint along the way.
995 * Each time through the loop:
997 * If didmount==0, c is on the undomount side of the mount point.
998 * If didmount==1, c is on the domount side of the mount point.
999 * Either way, c's full path is path.
1002 for(nhave=0; nhave<nnames; nhave+=n){
1003 if((c->qid.type&QTDIR)==0){
1008 kstrcpy(up->errstr, Enotdir, ERRMAX);
1013 ntry = nnames - nhave;
1017 for(i=0; i<ntry; i++){
1018 if(isdotdot(names[nhave+i])){
1028 if(!dotdot && !nomount && !didmount)
1029 domount(&c, &mh, &path);
1034 if((wq = ewalk(c, nil, names+nhave, ntry)) == nil){
1035 /* try a union mount, if any */
1038 * mh->mount->to == c, so start at mh->mount->next
1041 if((f = mh->mount) != nil)
1043 for(; f != nil; f = f->next)
1044 if((wq = ewalk(f->to, nil, names+nhave, ntry)) != nil){
1064 assert(wq->nqid == 1);
1065 assert(wq->clone != nil);
1067 path = addelem(path, "..", nil);
1068 nc = undomount(wq->clone, path);
1075 for(i=0; i<wq->nqid && i<ntry-1; i++){
1076 if(findmount(&nc, &nmh, type, dev, wq->qid[i])){
1082 if(nc == nil){ /* no mount points along path */
1083 if(wq->clone == nil){
1086 if(wq->nqid==0 || (wq->qid[wq->nqid-1].type&QTDIR)){
1088 *nerror = nhave+wq->nqid+1;
1089 kstrcpy(up->errstr, Edoesnotexist, ERRMAX);
1092 *nerror = nhave+wq->nqid;
1093 kstrcpy(up->errstr, Enotdir, ERRMAX);
1102 }else{ /* stopped early, at a mount point */
1104 if(wq->clone != nil){
1114 path = addelem(path, names[nhave+i], mtpt);
1128 if(c->umh != nil){ //BUG
1129 print("walk umh\n");
1145 * c is a mounted non-creatable directory. find a creatable one.
1148 createdir(Chan *c, Mhead *m)
1158 for(f = m->mount; f; f = f->next){
1159 if(f->mflag&MCREATE){
1177 growparse(Elemlist *e)
1183 if(e->nelems % Delta == 0){
1184 new = smalloc((e->nelems+Delta) * sizeof(char*));
1185 memmove(new, e->elems, e->nelems*sizeof(char*));
1188 inew = smalloc((e->nelems+Delta+1) * sizeof(int));
1189 memmove(inew, e->off, (e->nelems+1)*sizeof(int));
1196 * The name is known to be valid.
1197 * Copy the name so slashes can be overwritten.
1198 * An empty string will set nelem=0.
1199 * A path ending in / or /. or /.//./ etc. will have
1200 * e.mustbedir = 1, so that we correctly
1201 * reject, e.g., "/adm/users/." when /adm/users is a file
1202 * rather than a directory.
1205 parsename(char *aname, Elemlist *e)
1209 kstrdup(&e->name, aname);
1213 e->off = smalloc(sizeof(int));
1214 e->off[0] = skipslash(name) - name;
1216 name = skipslash(name);
1218 e->off[e->nelems] = name+strlen(name) - e->name;
1223 e->elems[e->nelems++] = name;
1224 slash = utfrune(name, '/');
1226 e->off[e->nelems] = name+strlen(name) - e->name;
1230 e->off[e->nelems] = slash - e->name;
1238 print("parsename %s:", e->name);
1239 for(i=0; i<=e->nelems; i++)
1240 print(" %d", e->off[i]);
1246 memrchr(void *va, int c, long n)
1251 for(e=a+n-1; e>a; e--)
1258 namelenerror(char *aname, int len, char *err)
1260 char *ename, *name, *next;
1264 * If the name is short enough, just use the whole thing.
1266 errlen = strlen(err);
1267 if(len < ERRMAX/3 || len+errlen < 2*ERRMAX/3)
1268 snprint(up->genbuf, sizeof up->genbuf, "%.*s",
1269 utfnlen(aname, len), aname);
1272 * Print a suffix of the name, but try to get a little info.
1278 next = memrchr(aname, '/', name-aname);
1282 }while(len < ERRMAX/3 || len + errlen < 2*ERRMAX/3);
1285 * If the name is ridiculously long, chop it.
1288 name = ename-ERRMAX/4;
1290 panic("bad math in namelenerror");
1291 /* walk out of current UTF sequence */
1292 for(i=0; (*name&0xC0)==0x80 && i<UTFmax; i++)
1295 snprint(up->genbuf, sizeof up->genbuf, "...%.*s",
1296 utfnlen(name, ename-name), name);
1298 snprint(up->errstr, ERRMAX, "%#q %s", up->genbuf, err);
1303 nameerror(char *name, char *err)
1305 namelenerror(name, strlen(name), err);
1309 * Turn a name into a channel.
1310 * &name[0] is known to be a valid address. It may be a kernel address.
1312 * Opening with amode Aopen, Acreate, Aremove, or Aaccess guarantees
1313 * that the result will be the only reference to that particular fid.
1314 * This is necessary since we might pass the result to
1315 * devtab[]->remove().
1317 * Opening Atodir or Amount does not guarantee this.
1319 * Under certain circumstances, opening Aaccess will cause
1320 * an unnecessary clone in order to get a cunique Chan so it
1321 * can attach the correct name. Sysstat and sys_stat need the
1322 * correct name so they can rewrite the stat info.
1325 namec(char *aname, int amode, int omode, ulong perm)
1327 int len, n, t, nomount;
1333 char *createerr, tmperrbuf[ERRMAX];
1336 if(aname[0] == '\0')
1337 error("empty file name");
1338 aname = validnamedup(aname, 1);
1343 DBG("namec %s %d %d\n", aname, amode, omode);
1347 * Find the starting off point (the current slash, the root of
1348 * a device tree, or the current dot) as well as the name to
1349 * evaluate starting there.
1360 up->genbuf[0] = '\0';
1362 while(*name != '\0' && (*name != '/' || n < 2)){
1363 if(n >= sizeof(up->genbuf)-1)
1365 up->genbuf[n++] = *name++;
1367 up->genbuf[n] = '\0';
1369 * noattach is sandboxing.
1371 * the OK exceptions are:
1372 * | it only gives access to pipes you create
1373 * d this process's file descriptors
1374 * e this process's environment
1375 * the iffy exceptions are:
1376 * c time and pid, but also cons and consctl
1377 * p control of your own processes (and unfortunately
1378 * any others left unprotected)
1380 n = chartorune(&r, up->genbuf+1)+1;
1381 /* actually / is caught by parsing earlier */
1384 if(up->pgrp->noattach && utfrune("|decp", r)==nil)
1389 c = devtab[t]->attach(up->genbuf+n);
1399 e.prefix = name - aname;
1410 * Prepare nice error, showing first e.nerror elements of name.
1414 strcpy(tmperrbuf, up->errstr);
1415 if(e.off[e.nerror]==0)
1416 print("nerror=%d but off=%d\n",
1417 e.nerror, e.off[e.nerror]);
1419 print("showing %d+%d/%d (of %d) of %s (%d %d)\n", e.prefix, e.off[e.nerror], e.nerror, e.nelems, aname, e.off[0], e.off[1]);
1420 len = e.prefix+e.off[e.nerror];
1422 namelenerror(aname, len, tmperrbuf);
1426 * Build a list of elements in the name.
1428 parsename(name, &e);
1433 if(amode == Acreate){
1434 /* perm must have DMDIR if last element is / or /. */
1435 if(e.mustbedir && !(perm&DMDIR)){
1436 e.nerror = e.nelems;
1437 error("create without DMDIR");
1440 /* don't try to walk the last path element just yet. */
1446 if(walk(&c, e.elems, e.nelems, nomount, &e.nerror) < 0){
1447 if(e.nerror < 0 || e.nerror > e.nelems){
1448 print("namec %s walk error nerror=%d\n", aname, e.nerror);
1454 if(e.mustbedir && !(c->qid.type&QTDIR))
1455 error("not a directory");
1457 if(amode == Aopen && (omode&3) == OEXEC && (c->qid.type&QTDIR))
1458 error("cannot exec directory");
1462 /* no need to maintain path - cannot dotdot an Abind */
1465 domount(&c, &m, nil);
1475 /* save&update the name; domount might change c */
1484 domount(&c, &m, &path);
1486 /* our own copy to open or remove */
1489 /* now it's our copy anyway, we can put the name back */
1494 /* record whether c is on a mount point */
1506 print("cunique umh Open\n");
1510 /* only save the mount head if it's a multiple element union */
1511 if(m && m->mount && m->mount->next)
1516 /* save registers else error() in open has wrong value of c saved */
1519 c = devtab[c->type]->open(c, omode&~OCEXEC);
1531 * Directories (e.g. for cd) are left before the mount point,
1532 * so one may mount on / or . and see the effect.
1534 if(!(c->qid.type & QTDIR))
1540 * When mounting on an already mounted upon directory,
1541 * one wants subsequent mounts to be attached to the
1542 * original directory, not the replacement. Don't domount.
1548 * We've already walked all but the last element.
1549 * If the last exists, try to open it OTRUNC.
1550 * If omode&OEXCL is set, just give up.
1554 if(walk(&c, e.elems+e.nelems-1, 1, nomount, nil) == 0){
1562 * The semantics of the create(2) system call are that if the
1563 * file exists and can be written, it is to be opened with truncation.
1564 * On the other hand, the create(5) message fails if the file exists.
1565 * If we get two create(2) calls happening simultaneously,
1566 * they might both get here and send create(5) messages, but only
1567 * one of the messages will succeed. To provide the expected create(2)
1568 * semantics, the call with the failed message needs to try the above
1569 * walk again, opening for truncation. This correctly solves the
1570 * create/create race, in the sense that any observable outcome can
1571 * be explained as one happening before the other.
1572 * The create/create race is quite common. For example, it happens
1573 * when two rc subshells simultaneously update the same
1574 * environment variable.
1576 * The implementation still admits a create/create/remove race:
1577 * (A) walk to file, fails
1578 * (B) walk to file, fails
1579 * (A) create file, succeeds, returns
1580 * (B) create file, fails
1581 * (A) remove file, succeeds, returns
1582 * (B) walk to file, return failure.
1584 * This is hardly as common as the create/create race, and is really
1585 * not too much worse than what might happen if (B) got a hold of a
1586 * file descriptor and then the file was removed -- either way (B) can't do
1587 * anything with the result of the create call. So we don't care about this race.
1589 * Applications that care about more fine-grained decision of the races
1590 * can use the OEXCL flag to get at the underlying create(5) semantics;
1591 * by default we provide the common case.
1593 * We need to stay behind the mount point in case we
1594 * need to do the first walk again (should the create fail).
1596 * We also need to cross the mount point and find the directory
1597 * in the union in which we should be creating.
1599 * The channel staying behind is c, the one moving forward is cnew.
1602 cnew = nil; /* is this assignment necessary? */
1603 if(!waserror()){ /* try create */
1604 if(!nomount && findmount(&cnew, &m, c->type, c->dev, c->qid))
1605 cnew = createdir(cnew, m);
1612 * We need our own copy of the Chan because we're
1613 * about to send a create, which will move it. Once we have
1614 * our own copy, we can fix the name, which might be wrong
1615 * if findmount gave us a new Chan.
1617 cnew = cunique(cnew);
1618 pathclose(cnew->path);
1619 cnew->path = c->path;
1622 cnew = devtab[cnew->type]->create(cnew, e.elems[e.nelems-1], omode&~(OEXCL|OCEXEC), perm);
1625 cnew->flag |= CCEXEC;
1627 cnew->flag |= CRCLOSE;
1632 c->path = addelem(c->path, e.elems[e.nelems-1], nil);
1643 createerr = up->errstr;
1644 up->errstr = tmperrbuf;
1645 /* note: we depend that walk does not error */
1646 if(walk(&c, e.elems+e.nelems-1, 1, nomount, nil) < 0){
1647 up->errstr = createerr;
1648 error(createerr); /* report true error */
1650 up->errstr = createerr;
1655 panic("unknown namec access %d", amode);
1658 /* place final element in genbuf for e.g. exec */
1660 kstrcpy(up->genbuf, e.elems[e.nelems-1], sizeof up->genbuf);
1662 kstrcpy(up->genbuf, ".", sizeof up->genbuf);
1666 poperror(); /* e c */
1668 poperror(); /* aname */
1674 * name is valid. skip leading / and ./ as much as possible
1677 skipslash(char *name)
1679 while(name[0]=='/' || (name[0]=='.' && (name[1]==0 || name[1]=='/')))
1685 /*NUL*/ 1, 1, 1, 1, 1, 1, 1, 1,
1686 /*BKS*/ 1, 1, 1, 1, 1, 1, 1, 1,
1687 /*DLE*/ 1, 1, 1, 1, 1, 1, 1, 1,
1688 /*CAN*/ 1, 1, 1, 1, 1, 1, 1, 1,
1694 * Check that the name
1695 * a) is in valid memory.
1696 * b) is shorter than 2^16 bytes, so it can fit in a 9P string field.
1697 * c) contains no frogs.
1698 * The first byte is known to be addressible by the requester, so the
1699 * routine works for kernel and user memory both.
1700 * The parameter slashok flags whether a slash character is an error
1701 * or a valid character.
1703 * The parameter dup flags whether the string should be copied
1704 * out of user space before being scanned the second time.
1705 * (Otherwise a malicious thread could remove the NUL, causing us
1706 * to access unchecked addresses.)
1709 validname0(char *aname, int slashok, int dup, ulong pc)
1711 char *ename, *name, *s;
1716 if((ulong)name < KZERO){
1718 print("warning: validname called from %#p with user pointer", pc);
1719 ename = vmemchr(name, 0, (1<<16));
1721 ename = memchr(name, 0, (1<<16));
1723 if(ename==nil || ename-name>=(1<<16))
1724 error("name too long");
1730 memmove(s, name, n);
1734 setmalloctag(s, pc);
1738 /* all characters above '~' are ok */
1741 name += chartorune(&r, name);
1744 if(!slashok || c!='/'){
1745 snprint(up->genbuf, sizeof(up->genbuf), "%s: %q", Ebadchar, aname);
1756 validname(char *aname, int slashok)
1758 validname0(aname, slashok, 0, getcallerpc(&aname));
1762 validnamedup(char *aname, int slashok)
1764 return validname0(aname, slashok, 1, getcallerpc(&aname));
1770 if(c->qid.type & QTDIR)
1776 * This is necessary because there are many
1777 * pointers to the top of a given mount list:
1779 * - the mhead in the namespace hash table
1780 * - the mhead in chans returned from findmount:
1781 * used in namec and then by unionread.
1782 * - the mhead in chans returned from createdir:
1783 * used in the open/create race protect, which is gone.
1785 * The RWlock in the Mhead protects the mount list it contains.
1786 * The mount list is deleted when we cunmount.
1787 * The RWlock ensures that nothing is using the mount list at that time.
1789 * It is okay to replace c->mh with whatever you want as
1790 * long as you are sure you have a unique reference to it.
1792 * This comment might belong somewhere else.
1797 if(m && decref(m) == 0){
1798 m->mount = (Mount*)0xCafeBeef;