1495 lines
29 KiB
C
1495 lines
29 KiB
C
#include "u.h"
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#include "lib.h"
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#include "dat.h"
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#include "fns.h"
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#include "error.h"
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int chandebug=0; /* toggled by sysr1 */
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QLock chanprint; /* probably asking for trouble (deadlocks) -rsc */
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int domount(Chan**, Mhead**);
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void
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dumpmount(void) /* DEBUGGING */
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{
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Pgrp *pg;
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Mount *t;
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Mhead **h, **he, *f;
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if(up == nil){
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print("no process for dumpmount\n");
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return;
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}
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pg = up->pgrp;
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if(pg == nil){
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print("no pgrp for dumpmount\n");
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return;
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}
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rlock(&pg->ns);
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if(waserror()) {
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runlock(&pg->ns);
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nexterror();
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}
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he = &pg->mnthash[MNTHASH];
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for(h = pg->mnthash; h < he; h++) {
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for(f = *h; f; f = f->hash) {
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print("head: %p: %s 0x%llux.%lud %C %lud -> \n", f,
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f->from->name->s, f->from->qid.path,
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f->from->qid.vers, devtab[f->from->type]->dc,
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f->from->dev);
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for(t = f->mount; t; t = t->next)
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print("\t%p: %s (umh %p) (path %.8llux dev %C %lud)\n", t, t->to->name->s, t->to->umh, t->to->qid.path, devtab[t->to->type]->dc, t->to->dev);
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}
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}
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poperror();
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runlock(&pg->ns);
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}
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char*
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c2name(Chan *c) /* DEBUGGING */
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{
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if(c == nil)
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return "<nil chan>";
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if(c->name == nil)
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return "<nil name>";
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if(c->name->s == nil)
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return "<nil name.s>";
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return c->name->s;
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}
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enum
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{
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CNAMESLOP = 20
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};
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struct
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{
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Lock lk;
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int fid;
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Chan *free;
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Chan *list;
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}chanalloc;
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typedef struct Elemlist Elemlist;
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struct Elemlist
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{
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char *name; /* copy of name, so '/' can be overwritten */
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int nelems;
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char **elems;
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int *off;
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int mustbedir;
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};
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#define SEP(c) ((c) == 0 || (c) == '/')
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void cleancname(Cname*);
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int
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isdotdot(char *p)
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{
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return p[0]=='.' && p[1]=='.' && p[2]=='\0';
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}
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int
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incref(Ref *r)
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{
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int x;
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lock(&r->lk);
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x = ++r->ref;
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unlock(&r->lk);
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return x;
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}
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int
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decref(Ref *r)
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{
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int x;
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lock(&r->lk);
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x = --r->ref;
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unlock(&r->lk);
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if(x < 0)
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panic("decref, pc=0x%p", getcallerpc(&r));
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return x;
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}
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/*
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* Rather than strncpy, which zeros the rest of the buffer, kstrcpy
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* truncates if necessary, always zero terminates, does not zero fill,
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* and puts ... at the end of the string if it's too long. Usually used to
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* save a string in up->genbuf;
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*/
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void
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kstrcpy(char *s, char *t, int ns)
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{
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int nt;
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nt = strlen(t);
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if(nt+1 <= ns){
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memmove(s, t, nt+1);
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return;
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}
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/* too long */
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if(ns < 4){
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/* but very short! */
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strncpy(s, t, ns);
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return;
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}
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/* truncate with ... at character boundary (very rare case) */
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memmove(s, t, ns-4);
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ns -= 4;
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s[ns] = '\0';
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/* look for first byte of UTF-8 sequence by skipping continuation bytes */
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while(ns>0 && (s[--ns]&0xC0)==0x80)
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;
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strcpy(s+ns, "...");
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}
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int
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emptystr(char *s)
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{
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if(s == nil)
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return 1;
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if(s[0] == '\0')
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return 1;
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return 0;
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}
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/*
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* Atomically replace *p with copy of s
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*/
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void
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kstrdup(char **p, char *s)
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{
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int n;
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char *t, *prev;
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n = strlen(s)+1;
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/* if it's a user, we can wait for memory; if not, something's very wrong */
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if(up){
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t = smalloc(n);
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setmalloctag(t, getcallerpc(&p));
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}else{
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t = malloc(n);
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if(t == nil)
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panic("kstrdup: no memory");
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}
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memmove(t, s, n);
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prev = *p;
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*p = t;
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free(prev);
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}
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void
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chandevreset(void)
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{
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int i;
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for(i=0; devtab[i] != nil; i++)
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devtab[i]->reset();
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}
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void
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chandevinit(void)
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{
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int i;
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for(i=0; devtab[i] != nil; i++)
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devtab[i]->init();
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}
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void
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chandevshutdown(void)
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{
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int i;
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/* shutdown in reverse order */
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for(i=0; devtab[i] != nil; i++)
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;
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for(i--; i >= 0; i--)
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devtab[i]->shutdown();
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}
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Chan*
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newchan(void)
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{
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Chan *c;
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lock(&chanalloc.lk);
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c = chanalloc.free;
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if(c != 0)
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chanalloc.free = c->next;
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unlock(&chanalloc.lk);
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if(c == nil) {
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c = smalloc(sizeof(Chan));
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lock(&chanalloc.lk);
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c->fid = ++chanalloc.fid;
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c->link = chanalloc.list;
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chanalloc.list = c;
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unlock(&chanalloc.lk);
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}
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/* if you get an error before associating with a dev,
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close calls rootclose, a nop */
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c->type = 0;
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c->flag = 0;
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c->ref.ref = 1;
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c->dev = 0;
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c->offset = 0;
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c->iounit = 0;
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c->umh = 0;
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c->uri = 0;
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c->dri = 0;
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c->aux = 0;
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c->mchan = 0;
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c->mcp = 0;
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c->mux = 0;
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memset(&c->mqid, 0, sizeof(c->mqid));
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c->name = 0;
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return c;
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}
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static Ref ncname;
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Cname*
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newcname(char *s)
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{
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Cname *n;
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int i;
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n = smalloc(sizeof(Cname));
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i = strlen(s);
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n->len = i;
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n->alen = i+CNAMESLOP;
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n->s = smalloc(n->alen);
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memmove(n->s, s, i+1);
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n->ref.ref = 1;
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incref(&ncname);
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return n;
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}
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void
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cnameclose(Cname *n)
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{
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if(n == nil)
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return;
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if(decref(&n->ref))
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return;
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decref(&ncname);
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free(n->s);
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free(n);
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}
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Cname*
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addelem(Cname *n, char *s)
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{
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int i, a;
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char *t;
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Cname *new;
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if(s[0]=='.' && s[1]=='\0')
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return n;
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if(n->ref.ref > 1){
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/* copy on write */
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new = newcname(n->s);
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cnameclose(n);
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n = new;
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}
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i = strlen(s);
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if(n->len+1+i+1 > n->alen){
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a = n->len+1+i+1 + CNAMESLOP;
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t = smalloc(a);
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memmove(t, n->s, n->len+1);
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free(n->s);
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n->s = t;
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n->alen = a;
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}
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if(n->len>0 && n->s[n->len-1]!='/' && s[0]!='/') /* don't insert extra slash if one is present */
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n->s[n->len++] = '/';
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memmove(n->s+n->len, s, i+1);
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n->len += i;
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if(isdotdot(s))
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cleancname(n);
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return n;
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}
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void
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chanfree(Chan *c)
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{
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c->flag = CFREE;
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if(c->umh != nil){
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putmhead(c->umh);
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c->umh = nil;
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}
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if(c->umc != nil){
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cclose(c->umc);
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c->umc = nil;
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}
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if(c->mux != nil){
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muxclose(c->mux);
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c->mux = nil;
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}
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if(c->mchan != nil){
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cclose(c->mchan);
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c->mchan = nil;
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}
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cnameclose(c->name);
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lock(&chanalloc.lk);
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c->next = chanalloc.free;
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chanalloc.free = c;
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unlock(&chanalloc.lk);
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}
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void
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cclose(Chan *c)
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{
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if(c->flag&CFREE)
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panic("cclose %p", getcallerpc(&c));
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if(decref(&c->ref))
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return;
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if(!waserror()){
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devtab[c->type]->close(c);
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poperror();
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}
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chanfree(c);
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}
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/*
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* Make sure we have the only copy of c. (Copy on write.)
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*/
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Chan*
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cunique(Chan *c)
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{
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Chan *nc;
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if(c->ref.ref != 1) {
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nc = cclone(c);
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cclose(c);
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c = nc;
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}
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return c;
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}
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int
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eqqid(Qid a, Qid b)
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{
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return a.path==b.path && a.vers==b.vers;
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}
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int
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eqchan(Chan *a, Chan *b, int pathonly)
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{
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if(a->qid.path != b->qid.path)
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return 0;
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if(!pathonly && a->qid.vers!=b->qid.vers)
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return 0;
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if(a->type != b->type)
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return 0;
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if(a->dev != b->dev)
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return 0;
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return 1;
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}
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int
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eqchantdqid(Chan *a, int type, int dev, Qid qid, int pathonly)
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{
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if(a->qid.path != qid.path)
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return 0;
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if(!pathonly && a->qid.vers!=qid.vers)
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return 0;
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if(a->type != type)
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return 0;
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if(a->dev != dev)
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return 0;
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return 1;
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}
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Mhead*
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newmhead(Chan *from)
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{
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Mhead *mh;
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mh = smalloc(sizeof(Mhead));
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mh->ref.ref = 1;
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mh->from = from;
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incref(&from->ref);
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/*
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n = from->name->len;
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if(n >= sizeof(mh->fromname))
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n = sizeof(mh->fromname)-1;
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memmove(mh->fromname, from->name->s, n);
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mh->fromname[n] = 0;
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*/
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return mh;
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}
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int
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cmount(Chan **newp, Chan *old, int flag, char *spec)
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{
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Pgrp *pg;
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int order, flg;
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Mhead *m, **l, *mh;
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Mount *nm, *f, *um, **h;
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Chan *new;
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if(QTDIR & (old->qid.type^(*newp)->qid.type))
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error(Emount);
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if(old->umh)print("cmount old extra umh\n");
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order = flag&MORDER;
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if((old->qid.type&QTDIR)==0 && order != MREPL)
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error(Emount);
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new = *newp;
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mh = new->umh;
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/*
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* Not allowed to bind when the old directory
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* is itself a union. (Maybe it should be allowed, but I don't see
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* what the semantics would be.)
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*
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* We need to check mh->mount->next to tell unions apart from
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* simple mount points, so that things like
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* mount -c fd /root
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* bind -c /root /
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* work. The check of mount->mflag catches things like
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* mount fd /root
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* bind -c /root /
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*
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* This is far more complicated than it should be, but I don't
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* see an easier way at the moment. -rsc
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*/
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if((flag&MCREATE) && mh && mh->mount
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&& (mh->mount->next || !(mh->mount->mflag&MCREATE)))
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error(Emount);
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pg = up->pgrp;
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wlock(&pg->ns);
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l = &MOUNTH(pg, old->qid);
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for(m = *l; m; m = m->hash) {
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if(eqchan(m->from, old, 1))
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break;
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l = &m->hash;
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}
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if(m == nil) {
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/*
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* nothing mounted here yet. create a mount
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* head and add to the hash table.
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*/
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m = newmhead(old);
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*l = m;
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/*
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* if this is a union mount, add the old
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* node to the mount chain.
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*/
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if(order != MREPL)
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m->mount = newmount(m, old, 0, 0);
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}
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wlock(&m->lock);
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if(waserror()){
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wunlock(&m->lock);
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nexterror();
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}
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wunlock(&pg->ns);
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nm = newmount(m, new, flag, spec);
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if(mh != nil && mh->mount != nil) {
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/*
|
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* copy a union when binding it onto a directory
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*/
|
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flg = order;
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if(order == MREPL)
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flg = MAFTER;
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h = &nm->next;
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um = mh->mount;
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for(um = um->next; um; um = um->next) {
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f = newmount(m, um->to, flg, um->spec);
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*h = f;
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h = &f->next;
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}
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}
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|
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if(m->mount && order == MREPL) {
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mountfree(m->mount);
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m->mount = 0;
|
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}
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|
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if(flag & MCREATE)
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nm->mflag |= MCREATE;
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|
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if(m->mount && order == MAFTER) {
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for(f = m->mount; f->next; f = f->next)
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;
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f->next = nm;
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}
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else {
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for(f = nm; f->next; f = f->next)
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;
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f->next = m->mount;
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m->mount = nm;
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}
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|
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wunlock(&m->lock);
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poperror();
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return nm->mountid;
|
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}
|
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|
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void
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cunmount(Chan *mnt, Chan *mounted)
|
|
{
|
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Pgrp *pg;
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Mhead *m, **l;
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Mount *f, **p;
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if(mnt->umh) /* should not happen */
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print("cunmount newp extra umh %p has %p\n", mnt, mnt->umh);
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|
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/*
|
|
* It _can_ happen that mounted->umh is non-nil,
|
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* because mounted is the result of namec(Aopen)
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|
* (see sysfile.c:/^sysunmount).
|
|
* If we open a union directory, it will have a umh.
|
|
* Although surprising, this is okay, since the
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* cclose will take care of freeing the umh.
|
|
*/
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|
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pg = up->pgrp;
|
|
wlock(&pg->ns);
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|
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l = &MOUNTH(pg, mnt->qid);
|
|
for(m = *l; m; m = m->hash) {
|
|
if(eqchan(m->from, mnt, 1))
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break;
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l = &m->hash;
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}
|
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|
|
if(m == 0) {
|
|
wunlock(&pg->ns);
|
|
error(Eunmount);
|
|
}
|
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|
|
wlock(&m->lock);
|
|
if(mounted == 0) {
|
|
*l = m->hash;
|
|
wunlock(&pg->ns);
|
|
mountfree(m->mount);
|
|
m->mount = nil;
|
|
cclose(m->from);
|
|
wunlock(&m->lock);
|
|
putmhead(m);
|
|
return;
|
|
}
|
|
|
|
p = &m->mount;
|
|
for(f = *p; f; f = f->next) {
|
|
/* BUG: Needs to be 2 pass */
|
|
if(eqchan(f->to, mounted, 1) ||
|
|
(f->to->mchan && eqchan(f->to->mchan, mounted, 1))) {
|
|
*p = f->next;
|
|
f->next = 0;
|
|
mountfree(f);
|
|
if(m->mount == nil) {
|
|
*l = m->hash;
|
|
cclose(m->from);
|
|
wunlock(&m->lock);
|
|
wunlock(&pg->ns);
|
|
putmhead(m);
|
|
return;
|
|
}
|
|
wunlock(&m->lock);
|
|
wunlock(&pg->ns);
|
|
return;
|
|
}
|
|
p = &f->next;
|
|
}
|
|
wunlock(&m->lock);
|
|
wunlock(&pg->ns);
|
|
error(Eunion);
|
|
}
|
|
|
|
Chan*
|
|
cclone(Chan *c)
|
|
{
|
|
Chan *nc;
|
|
Walkqid *wq;
|
|
|
|
wq = devtab[c->type]->walk(c, nil, nil, 0);
|
|
if(wq == nil)
|
|
error("clone failed");
|
|
nc = wq->clone;
|
|
free(wq);
|
|
nc->name = c->name;
|
|
if(c->name)
|
|
incref(&c->name->ref);
|
|
return nc;
|
|
}
|
|
|
|
int
|
|
findmount(Chan **cp, Mhead **mp, int type, int dev, Qid qid)
|
|
{
|
|
Pgrp *pg;
|
|
Mhead *m;
|
|
|
|
pg = up->pgrp;
|
|
rlock(&pg->ns);
|
|
for(m = MOUNTH(pg, qid); m; m = m->hash){
|
|
rlock(&m->lock);
|
|
if(m->from == nil){
|
|
print("m %p m->from 0\n", m);
|
|
runlock(&m->lock);
|
|
continue;
|
|
}
|
|
if(eqchantdqid(m->from, type, dev, qid, 1)) {
|
|
runlock(&pg->ns);
|
|
if(mp != nil){
|
|
incref(&m->ref);
|
|
if(*mp != nil)
|
|
putmhead(*mp);
|
|
*mp = m;
|
|
}
|
|
if(*cp != nil)
|
|
cclose(*cp);
|
|
incref(&m->mount->to->ref);
|
|
*cp = m->mount->to;
|
|
runlock(&m->lock);
|
|
return 1;
|
|
}
|
|
runlock(&m->lock);
|
|
}
|
|
|
|
runlock(&pg->ns);
|
|
return 0;
|
|
}
|
|
|
|
int
|
|
domount(Chan **cp, Mhead **mp)
|
|
{
|
|
return findmount(cp, mp, (*cp)->type, (*cp)->dev, (*cp)->qid);
|
|
}
|
|
|
|
Chan*
|
|
undomount(Chan *c, Cname *name)
|
|
{
|
|
Chan *nc;
|
|
Pgrp *pg;
|
|
Mount *t;
|
|
Mhead **h, **he, *f;
|
|
|
|
pg = up->pgrp;
|
|
rlock(&pg->ns);
|
|
if(waserror()) {
|
|
runlock(&pg->ns);
|
|
nexterror();
|
|
}
|
|
|
|
he = &pg->mnthash[MNTHASH];
|
|
for(h = pg->mnthash; h < he; h++) {
|
|
for(f = *h; f; f = f->hash) {
|
|
if(strcmp(f->from->name->s, name->s) != 0)
|
|
continue;
|
|
for(t = f->mount; t; t = t->next) {
|
|
if(eqchan(c, t->to, 1)) {
|
|
/*
|
|
* We want to come out on the left hand side of the mount
|
|
* point using the element of the union that we entered on.
|
|
* To do this, find the element that has a from name of
|
|
* c->name->s.
|
|
*/
|
|
if(strcmp(t->head->from->name->s, name->s) != 0)
|
|
continue;
|
|
nc = t->head->from;
|
|
incref(&nc->ref);
|
|
cclose(c);
|
|
c = nc;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
poperror();
|
|
runlock(&pg->ns);
|
|
return c;
|
|
}
|
|
|
|
/*
|
|
* Either walks all the way or not at all. No partial results in *cp.
|
|
* *nerror is the number of names to display in an error message.
|
|
*/
|
|
static char Edoesnotexist[] = "does not exist";
|
|
int
|
|
walk(Chan **cp, char **names, int nnames, int nomount, int *nerror)
|
|
{
|
|
int dev, dotdot, i, n, nhave, ntry, type;
|
|
Chan *c, *nc;
|
|
Cname *cname;
|
|
Mount *f;
|
|
Mhead *mh, *nmh;
|
|
Walkqid *wq;
|
|
|
|
c = *cp;
|
|
incref(&c->ref);
|
|
cname = c->name;
|
|
incref(&cname->ref);
|
|
mh = nil;
|
|
|
|
/*
|
|
* While we haven't gotten all the way down the path:
|
|
* 1. step through a mount point, if any
|
|
* 2. send a walk request for initial dotdot or initial prefix without dotdot
|
|
* 3. move to the first mountpoint along the way.
|
|
* 4. repeat.
|
|
*
|
|
* An invariant is that each time through the loop, c is on the undomount
|
|
* side of the mount point, and c's name is cname.
|
|
*/
|
|
for(nhave=0; nhave<nnames; nhave+=n){
|
|
if((c->qid.type&QTDIR)==0){
|
|
if(nerror)
|
|
*nerror = nhave;
|
|
cnameclose(cname);
|
|
cclose(c);
|
|
strcpy(up->errstr, Enotdir);
|
|
if(mh != nil)
|
|
{print("walk 1\n");
|
|
putmhead(mh);
|
|
}
|
|
return -1;
|
|
}
|
|
ntry = nnames - nhave;
|
|
if(ntry > MAXWELEM)
|
|
ntry = MAXWELEM;
|
|
dotdot = 0;
|
|
for(i=0; i<ntry; i++){
|
|
if(isdotdot(names[nhave+i])){
|
|
if(i==0) {
|
|
dotdot = 1;
|
|
ntry = 1;
|
|
} else
|
|
ntry = i;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if(!dotdot && !nomount)
|
|
domount(&c, &mh);
|
|
|
|
type = c->type;
|
|
dev = c->dev;
|
|
|
|
if((wq = devtab[type]->walk(c, nil, names+nhave, ntry)) == nil){
|
|
/* try a union mount, if any */
|
|
if(mh && !nomount){
|
|
/*
|
|
* mh->mount == c, so start at mh->mount->next
|
|
*/
|
|
rlock(&mh->lock);
|
|
for(f = mh->mount->next; f; f = f->next)
|
|
if((wq = devtab[f->to->type]->walk(f->to, nil, names+nhave, ntry)) != nil)
|
|
break;
|
|
runlock(&mh->lock);
|
|
if(f != nil){
|
|
type = f->to->type;
|
|
dev = f->to->dev;
|
|
}
|
|
}
|
|
if(wq == nil){
|
|
cclose(c);
|
|
cnameclose(cname);
|
|
if(nerror)
|
|
*nerror = nhave+1;
|
|
if(mh != nil)
|
|
putmhead(mh);
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
nmh = nil;
|
|
if(dotdot) {
|
|
assert(wq->nqid == 1);
|
|
assert(wq->clone != nil);
|
|
|
|
cname = addelem(cname, "..");
|
|
nc = undomount(wq->clone, cname);
|
|
n = 1;
|
|
} else {
|
|
nc = nil;
|
|
if(!nomount)
|
|
for(i=0; i<wq->nqid && i<ntry-1; i++)
|
|
if(findmount(&nc, &nmh, type, dev, wq->qid[i]))
|
|
break;
|
|
if(nc == nil){ /* no mount points along path */
|
|
if(wq->clone == nil){
|
|
cclose(c);
|
|
cnameclose(cname);
|
|
if(wq->nqid==0 || (wq->qid[wq->nqid-1].type&QTDIR)){
|
|
if(nerror)
|
|
*nerror = nhave+wq->nqid+1;
|
|
strcpy(up->errstr, Edoesnotexist);
|
|
}else{
|
|
if(nerror)
|
|
*nerror = nhave+wq->nqid;
|
|
strcpy(up->errstr, Enotdir);
|
|
}
|
|
free(wq);
|
|
if(mh != nil)
|
|
putmhead(mh);
|
|
return -1;
|
|
}
|
|
n = wq->nqid;
|
|
nc = wq->clone;
|
|
}else{ /* stopped early, at a mount point */
|
|
if(wq->clone != nil){
|
|
cclose(wq->clone);
|
|
wq->clone = nil;
|
|
}
|
|
n = i+1;
|
|
}
|
|
for(i=0; i<n; i++)
|
|
cname = addelem(cname, names[nhave+i]);
|
|
}
|
|
cclose(c);
|
|
c = nc;
|
|
putmhead(mh);
|
|
mh = nmh;
|
|
free(wq);
|
|
}
|
|
|
|
putmhead(mh);
|
|
|
|
c = cunique(c);
|
|
|
|
if(c->umh != nil){ //BUG
|
|
print("walk umh\n");
|
|
putmhead(c->umh);
|
|
c->umh = nil;
|
|
}
|
|
|
|
cnameclose(c->name);
|
|
c->name = cname;
|
|
|
|
cclose(*cp);
|
|
*cp = c;
|
|
if(nerror)
|
|
*nerror = 0;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* c is a mounted non-creatable directory. find a creatable one.
|
|
*/
|
|
Chan*
|
|
createdir(Chan *c, Mhead *m)
|
|
{
|
|
Chan *nc;
|
|
Mount *f;
|
|
|
|
rlock(&m->lock);
|
|
if(waserror()) {
|
|
runlock(&m->lock);
|
|
nexterror();
|
|
}
|
|
for(f = m->mount; f; f = f->next) {
|
|
if(f->mflag&MCREATE) {
|
|
nc = cclone(f->to);
|
|
runlock(&m->lock);
|
|
poperror();
|
|
cclose(c);
|
|
return nc;
|
|
}
|
|
}
|
|
error(Enocreate);
|
|
return 0;
|
|
}
|
|
|
|
void
|
|
saveregisters(void)
|
|
{
|
|
}
|
|
|
|
/*
|
|
* In place, rewrite name to compress multiple /, eliminate ., and process ..
|
|
*/
|
|
void
|
|
cleancname(Cname *n)
|
|
{
|
|
char *p;
|
|
|
|
if(n->s[0] == '#'){
|
|
p = strchr(n->s, '/');
|
|
if(p == nil)
|
|
return;
|
|
cleanname(p);
|
|
|
|
/*
|
|
* The correct name is #i rather than #i/,
|
|
* but the correct name of #/ is #/.
|
|
*/
|
|
if(strcmp(p, "/")==0 && n->s[1] != '/')
|
|
*p = '\0';
|
|
}else
|
|
cleanname(n->s);
|
|
n->len = strlen(n->s);
|
|
}
|
|
|
|
static void
|
|
growparse(Elemlist *e)
|
|
{
|
|
char **new;
|
|
int *inew;
|
|
enum { Delta = 8 };
|
|
|
|
if(e->nelems % Delta == 0){
|
|
new = smalloc((e->nelems+Delta) * sizeof(char*));
|
|
memmove(new, e->elems, e->nelems*sizeof(char*));
|
|
free(e->elems);
|
|
e->elems = new;
|
|
inew = smalloc((e->nelems+Delta+1) * sizeof(int));
|
|
memmove(inew, e->off, e->nelems*sizeof(int));
|
|
free(e->off);
|
|
e->off = inew;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The name is known to be valid.
|
|
* Copy the name so slashes can be overwritten.
|
|
* An empty string will set nelem=0.
|
|
* A path ending in / or /. or /.//./ etc. will have
|
|
* e.mustbedir = 1, so that we correctly
|
|
* reject, e.g., "/adm/users/." when /adm/users is a file
|
|
* rather than a directory.
|
|
*/
|
|
static void
|
|
parsename(char *name, Elemlist *e)
|
|
{
|
|
char *slash;
|
|
|
|
kstrdup(&e->name, name);
|
|
name = e->name;
|
|
e->nelems = 0;
|
|
e->elems = nil;
|
|
e->off = smalloc(sizeof(int));
|
|
e->off[0] = skipslash(name) - name;
|
|
for(;;){
|
|
name = skipslash(name);
|
|
if(*name=='\0'){
|
|
e->mustbedir = 1;
|
|
break;
|
|
}
|
|
growparse(e);
|
|
e->elems[e->nelems++] = name;
|
|
slash = utfrune(name, '/');
|
|
if(slash == nil){
|
|
e->off[e->nelems] = name+strlen(name) - e->name;
|
|
e->mustbedir = 0;
|
|
break;
|
|
}
|
|
e->off[e->nelems] = slash - e->name;
|
|
*slash++ = '\0';
|
|
name = slash;
|
|
}
|
|
}
|
|
|
|
void*
|
|
memrchr(void *va, int c, long n)
|
|
{
|
|
uchar *a, *e;
|
|
|
|
a = va;
|
|
for(e=a+n-1; e>a; e--)
|
|
if(*e == c)
|
|
return e;
|
|
return nil;
|
|
}
|
|
|
|
/*
|
|
* Turn a name into a channel.
|
|
* &name[0] is known to be a valid address. It may be a kernel address.
|
|
*
|
|
* Opening with amode Aopen, Acreate, or Aremove guarantees
|
|
* that the result will be the only reference to that particular fid.
|
|
* This is necessary since we might pass the result to
|
|
* devtab[]->remove().
|
|
*
|
|
* Opening Atodir, Amount, or Aaccess does not guarantee this.
|
|
*
|
|
* Opening Aaccess can, under certain conditions, return a
|
|
* correct Chan* but with an incorrect Cname attached.
|
|
* Since the functions that open Aaccess (sysstat, syswstat, sys_stat)
|
|
* do not use the Cname*, this avoids an unnecessary clone.
|
|
*/
|
|
Chan*
|
|
namec(char *aname, int amode, int omode, ulong perm)
|
|
{
|
|
int n, prefix, len, t, nomount, npath;
|
|
Chan *c, *cnew;
|
|
Cname *cname;
|
|
Elemlist e;
|
|
Rune r;
|
|
Mhead *m;
|
|
char *createerr, tmperrbuf[ERRMAX];
|
|
char *name;
|
|
|
|
name = aname;
|
|
if(name[0] == '\0')
|
|
error("empty file name");
|
|
validname(name, 1);
|
|
|
|
/*
|
|
* Find the starting off point (the current slash, the root of
|
|
* a device tree, or the current dot) as well as the name to
|
|
* evaluate starting there.
|
|
*/
|
|
nomount = 0;
|
|
switch(name[0]){
|
|
case '/':
|
|
c = up->slash;
|
|
incref(&c->ref);
|
|
break;
|
|
|
|
case '#':
|
|
nomount = 1;
|
|
up->genbuf[0] = '\0';
|
|
n = 0;
|
|
while(*name!='\0' && (*name != '/' || n < 2)){
|
|
if(n >= sizeof(up->genbuf)-1)
|
|
error(Efilename);
|
|
up->genbuf[n++] = *name++;
|
|
}
|
|
up->genbuf[n] = '\0';
|
|
/*
|
|
* noattach is sandboxing.
|
|
*
|
|
* the OK exceptions are:
|
|
* | it only gives access to pipes you create
|
|
* d this process's file descriptors
|
|
* e this process's environment
|
|
* the iffy exceptions are:
|
|
* c time and pid, but also cons and consctl
|
|
* p control of your own processes (and unfortunately
|
|
* any others left unprotected)
|
|
*/
|
|
n = chartorune(&r, up->genbuf+1)+1;
|
|
/* actually / is caught by parsing earlier */
|
|
if(utfrune("M", r))
|
|
error(Enoattach);
|
|
if(up->pgrp->noattach && utfrune("|decp", r)==nil)
|
|
error(Enoattach);
|
|
t = devno(r, 1);
|
|
if(t == -1)
|
|
error(Ebadsharp);
|
|
c = devtab[t]->attach(up->genbuf+n);
|
|
break;
|
|
|
|
default:
|
|
c = up->dot;
|
|
incref(&c->ref);
|
|
break;
|
|
}
|
|
prefix = name - aname;
|
|
|
|
e.name = nil;
|
|
e.elems = nil;
|
|
e.off = nil;
|
|
e.nelems = 0;
|
|
if(waserror()){
|
|
cclose(c);
|
|
free(e.name);
|
|
free(e.elems);
|
|
free(e.off);
|
|
//dumpmount();
|
|
nexterror();
|
|
}
|
|
|
|
/*
|
|
* Build a list of elements in the path.
|
|
*/
|
|
parsename(name, &e);
|
|
|
|
/*
|
|
* On create, ....
|
|
*/
|
|
if(amode == Acreate){
|
|
/* perm must have DMDIR if last element is / or /. */
|
|
if(e.mustbedir && !(perm&DMDIR)){
|
|
npath = e.nelems;
|
|
strcpy(tmperrbuf, "create without DMDIR");
|
|
goto NameError;
|
|
}
|
|
|
|
/* don't try to walk the last path element just yet. */
|
|
if(e.nelems == 0)
|
|
error(Eexist);
|
|
e.nelems--;
|
|
}
|
|
|
|
if(walk(&c, e.elems, e.nelems, nomount, &npath) < 0){
|
|
if(npath < 0 || npath > e.nelems){
|
|
print("namec %s walk error npath=%d\n", aname, npath);
|
|
nexterror();
|
|
}
|
|
strcpy(tmperrbuf, up->errstr);
|
|
NameError:
|
|
len = prefix+e.off[npath];
|
|
if(len < ERRMAX/3 || (name=memrchr(aname, '/', len))==nil || name==aname)
|
|
snprint(up->genbuf, sizeof up->genbuf, "%.*s", len, aname);
|
|
else
|
|
snprint(up->genbuf, sizeof up->genbuf, "...%.*s", (int)(len-(name-aname)), name);
|
|
snprint(up->errstr, ERRMAX, "%#q %s", up->genbuf, tmperrbuf);
|
|
nexterror();
|
|
}
|
|
|
|
if(e.mustbedir && !(c->qid.type&QTDIR)){
|
|
npath = e.nelems;
|
|
strcpy(tmperrbuf, "not a directory");
|
|
goto NameError;
|
|
}
|
|
|
|
if(amode == Aopen && (omode&3) == OEXEC && (c->qid.type&QTDIR)){
|
|
npath = e.nelems;
|
|
error("cannot exec directory");
|
|
}
|
|
|
|
switch(amode){
|
|
case Aaccess:
|
|
if(!nomount)
|
|
domount(&c, nil);
|
|
break;
|
|
|
|
case Abind:
|
|
m = nil;
|
|
if(!nomount)
|
|
domount(&c, &m);
|
|
if(c->umh != nil)
|
|
putmhead(c->umh);
|
|
c->umh = m;
|
|
break;
|
|
|
|
case Aremove:
|
|
case Aopen:
|
|
Open:
|
|
/* save the name; domount might change c */
|
|
cname = c->name;
|
|
incref(&cname->ref);
|
|
m = nil;
|
|
if(!nomount)
|
|
domount(&c, &m);
|
|
|
|
/* our own copy to open or remove */
|
|
c = cunique(c);
|
|
|
|
/* now it's our copy anyway, we can put the name back */
|
|
cnameclose(c->name);
|
|
c->name = cname;
|
|
|
|
switch(amode){
|
|
case Aremove:
|
|
putmhead(m);
|
|
break;
|
|
|
|
case Aopen:
|
|
case Acreate:
|
|
if(c->umh != nil){
|
|
print("cunique umh Open\n");
|
|
putmhead(c->umh);
|
|
c->umh = nil;
|
|
}
|
|
|
|
/* only save the mount head if it's a multiple element union */
|
|
if(m && m->mount && m->mount->next)
|
|
c->umh = m;
|
|
else
|
|
putmhead(m);
|
|
|
|
/* save registers else error() in open has wrong value of c saved */
|
|
saveregisters();
|
|
|
|
if(omode == OEXEC)
|
|
c->flag &= ~CCACHE;
|
|
|
|
c = devtab[c->type]->open(c, omode&~OCEXEC);
|
|
|
|
if(omode & OCEXEC)
|
|
c->flag |= CCEXEC;
|
|
if(omode & ORCLOSE)
|
|
c->flag |= CRCLOSE;
|
|
break;
|
|
}
|
|
break;
|
|
|
|
case Atodir:
|
|
/*
|
|
* Directories (e.g. for cd) are left before the mount point,
|
|
* so one may mount on / or . and see the effect.
|
|
*/
|
|
if(!(c->qid.type & QTDIR))
|
|
error(Enotdir);
|
|
break;
|
|
|
|
case Amount:
|
|
/*
|
|
* When mounting on an already mounted upon directory,
|
|
* one wants subsequent mounts to be attached to the
|
|
* original directory, not the replacement. Don't domount.
|
|
*/
|
|
break;
|
|
|
|
case Acreate:
|
|
/*
|
|
* We've already walked all but the last element.
|
|
* If the last exists, try to open it OTRUNC.
|
|
* If omode&OEXCL is set, just give up.
|
|
*/
|
|
e.nelems++;
|
|
if(walk(&c, e.elems+e.nelems-1, 1, nomount, nil) == 0){
|
|
if(omode&OEXCL)
|
|
error(Eexist);
|
|
omode |= OTRUNC;
|
|
goto Open;
|
|
}
|
|
|
|
/*
|
|
* The semantics of the create(2) system call are that if the
|
|
* file exists and can be written, it is to be opened with truncation.
|
|
* On the other hand, the create(5) message fails if the file exists.
|
|
* If we get two create(2) calls happening simultaneously,
|
|
* they might both get here and send create(5) messages, but only
|
|
* one of the messages will succeed. To provide the expected create(2)
|
|
* semantics, the call with the failed message needs to try the above
|
|
* walk again, opening for truncation. This correctly solves the
|
|
* create/create race, in the sense that any observable outcome can
|
|
* be explained as one happening before the other.
|
|
* The create/create race is quite common. For example, it happens
|
|
* when two rc subshells simultaneously update the same
|
|
* environment variable.
|
|
*
|
|
* The implementation still admits a create/create/remove race:
|
|
* (A) walk to file, fails
|
|
* (B) walk to file, fails
|
|
* (A) create file, succeeds, returns
|
|
* (B) create file, fails
|
|
* (A) remove file, succeeds, returns
|
|
* (B) walk to file, return failure.
|
|
*
|
|
* This is hardly as common as the create/create race, and is really
|
|
* not too much worse than what might happen if (B) got a hold of a
|
|
* file descriptor and then the file was removed -- either way (B) can't do
|
|
* anything with the result of the create call. So we don't care about this race.
|
|
*
|
|
* Applications that care about more fine-grained decision of the races
|
|
* can use the OEXCL flag to get at the underlying create(5) semantics;
|
|
* by default we provide the common case.
|
|
*
|
|
* We need to stay behind the mount point in case we
|
|
* need to do the first walk again (should the create fail).
|
|
*
|
|
* We also need to cross the mount point and find the directory
|
|
* in the union in which we should be creating.
|
|
*
|
|
* The channel staying behind is c, the one moving forward is cnew.
|
|
*/
|
|
m = nil;
|
|
cnew = nil; /* is this assignment necessary? */
|
|
if(!waserror()){ /* try create */
|
|
if(!nomount && findmount(&cnew, &m, c->type, c->dev, c->qid))
|
|
cnew = createdir(cnew, m);
|
|
else{
|
|
cnew = c;
|
|
incref(&cnew->ref);
|
|
}
|
|
|
|
/*
|
|
* We need our own copy of the Chan because we're
|
|
* about to send a create, which will move it. Once we have
|
|
* our own copy, we can fix the name, which might be wrong
|
|
* if findmount gave us a new Chan.
|
|
*/
|
|
cnew = cunique(cnew);
|
|
cnameclose(cnew->name);
|
|
cnew->name = c->name;
|
|
incref(&cnew->name->ref);
|
|
|
|
devtab[cnew->type]->create(cnew, e.elems[e.nelems-1], omode&~(OEXCL|OCEXEC), perm);
|
|
poperror();
|
|
if(omode & OCEXEC)
|
|
cnew->flag |= CCEXEC;
|
|
if(omode & ORCLOSE)
|
|
cnew->flag |= CRCLOSE;
|
|
if(m)
|
|
putmhead(m);
|
|
cclose(c);
|
|
c = cnew;
|
|
c->name = addelem(c->name, e.elems[e.nelems-1]);
|
|
break;
|
|
}else{ /* create failed */
|
|
cclose(cnew);
|
|
if(m)
|
|
putmhead(m);
|
|
if(omode & OEXCL)
|
|
nexterror();
|
|
/* save error */
|
|
createerr = up->errstr;
|
|
up->errstr = tmperrbuf;
|
|
/* note: we depend that walk does not error */
|
|
if(walk(&c, e.elems+e.nelems-1, 1, nomount, nil) < 0){
|
|
up->errstr = createerr;
|
|
error(createerr); /* report true error */
|
|
}
|
|
up->errstr = createerr;
|
|
omode |= OTRUNC;
|
|
goto Open;
|
|
}
|
|
panic("namec: not reached");
|
|
|
|
default:
|
|
panic("unknown namec access %d\n", amode);
|
|
}
|
|
|
|
poperror();
|
|
|
|
/* place final element in genbuf for e.g. exec */
|
|
if(e.nelems > 0)
|
|
kstrcpy(up->genbuf, e.elems[e.nelems-1], sizeof up->genbuf);
|
|
else
|
|
kstrcpy(up->genbuf, ".", sizeof up->genbuf);
|
|
free(e.name);
|
|
free(e.elems);
|
|
free(e.off);
|
|
|
|
return c;
|
|
}
|
|
|
|
/*
|
|
* name is valid. skip leading / and ./ as much as possible
|
|
*/
|
|
char*
|
|
skipslash(char *name)
|
|
{
|
|
while(name[0]=='/' || (name[0]=='.' && (name[1]==0 || name[1]=='/')))
|
|
name++;
|
|
return name;
|
|
}
|
|
|
|
char isfrog[256]={
|
|
/*NUL*/ 1, 1, 1, 1, 1, 1, 1, 1, /* 0 */
|
|
/*BKS*/ 1, 1, 1, 1, 1, 1, 1, 1, /* 0x08 */
|
|
/*DLE*/ 1, 1, 1, 1, 1, 1, 1, 1, /* 0x10 */
|
|
/*CAN*/ 1, 1, 1, 1, 1, 1, 1, 1, /* 0x18 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x20 */
|
|
0, 0, 0, 0, 0, 0, 0, 1, /* 0x28 (1 is '/', 0x2F) */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x30 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x38 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x40 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x48 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x50 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x58 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x60 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x68 */
|
|
0, 0, 0, 0, 0, 0, 0, 0, /* 0x70 */
|
|
0, 0, 0, 0, 0, 0, 0, 1, /* 0x78 (1 is DEL, 0x7F) */
|
|
};
|
|
|
|
/*
|
|
* Check that the name
|
|
* a) is in valid memory.
|
|
* b) is shorter than 2^16 bytes, so it can fit in a 9P string field.
|
|
* c) contains no frogs.
|
|
* The first byte is known to be addressible by the requester, so the
|
|
* routine works for kernel and user memory both.
|
|
* The parameter slashok flags whether a slash character is an error
|
|
* or a valid character.
|
|
*/
|
|
void
|
|
validname(char *aname, int slashok)
|
|
{
|
|
char *ename, *name;
|
|
int c;
|
|
Rune r;
|
|
|
|
name = aname;
|
|
/*
|
|
if(((ulong)name & KZERO) != KZERO) {
|
|
p = name;
|
|
t = BY2PG-((ulong)p&(BY2PG-1));
|
|
while((ename=vmemchr(p, 0, t)) == nil) {
|
|
p += t;
|
|
t = BY2PG;
|
|
}
|
|
}else
|
|
*/
|
|
ename = memchr(name, 0, (1<<16));
|
|
|
|
if(ename==nil || ename-name>=(1<<16))
|
|
error("name too long");
|
|
|
|
while(*name){
|
|
/* all characters above '~' are ok */
|
|
c = *(uchar*)name;
|
|
if(c >= Runeself)
|
|
name += chartorune(&r, name);
|
|
else{
|
|
if(isfrog[c])
|
|
if(!slashok || c!='/'){
|
|
snprint(up->genbuf, sizeof(up->genbuf), "%s: %q", Ebadchar, aname);
|
|
error(up->genbuf);
|
|
}
|
|
name++;
|
|
}
|
|
}
|
|
}
|
|
|
|
void
|
|
isdir(Chan *c)
|
|
{
|
|
if(c->qid.type & QTDIR)
|
|
return;
|
|
error(Enotdir);
|
|
}
|
|
|
|
/*
|
|
* This is necessary because there are many
|
|
* pointers to the top of a given mount list:
|
|
*
|
|
* - the mhead in the namespace hash table
|
|
* - the mhead in chans returned from findmount:
|
|
* used in namec and then by unionread.
|
|
* - the mhead in chans returned from createdir:
|
|
* used in the open/create race protect, which is gone.
|
|
*
|
|
* The RWlock in the Mhead protects the mount list it contains.
|
|
* The mount list is deleted when we cunmount.
|
|
* The RWlock ensures that nothing is using the mount list at that time.
|
|
*
|
|
* It is okay to replace c->mh with whatever you want as
|
|
* long as you are sure you have a unique reference to it.
|
|
*
|
|
* This comment might belong somewhere else.
|
|
*/
|
|
void
|
|
putmhead(Mhead *m)
|
|
{
|
|
if(m && decref(&m->ref) == 0){
|
|
m->mount = (Mount*)0xCafeBeef;
|
|
free(m);
|
|
}
|
|
}
|