/* * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <auth.h>#include <fcall.h>#include <thread.h>#include <9p.h> /* * To avoid deadlock, the following rules must be followed. * Always lock child then parent, never parent then child. * If holding the free file lock, do not lock any Files. */struct Filelist{ File *f; Filelist *link;}; struct Readdir{ File *dir; Filelist *fl;}; static QLock filelk;static File *freefilelist; static File*allocfile(void){ int i, a; File *f; enum { N = 16 }; qlock(&filelk); if(freefilelist == nil){ f = emalloc9p(N*sizeof(*f)); for(i=0; i<N-1; i++) f[i].aux = &f[i+1]; f[N-1].aux = nil; f[0].allocd = 1; freefilelist = f; } f = freefilelist; freefilelist = f->aux; qunlock(&filelk); a = f->allocd; memset(f, 0, sizeof *f); f->allocd = a; return f;} static voidfreefile(File *f){ Filelist *fl, *flnext; for(fl=f->filelist; fl; fl=flnext){ flnext = fl->link; assert(fl->f == nil); free(fl); } free(f->name); free(f->uid); free(f->gid); free(f->muid); qlock(&filelk); assert(f->ref == 0); f->aux = freefilelist; freefilelist = f; qunlock(&filelk);} static voidcleanfilelist(File *f){ Filelist **l; Filelist *fl; /* * can't delete filelist structures while there * are open readers of this directory, because * they might have references to the structures. * instead, just leave the empty refs in the list * until there is no activity and then clean up. */ if(f->readers.ref != 0) return; if(f->nxchild == 0) return; /* * no dir readers, file is locked, and * there are empty entries in the file list. * clean them out. */ for(l=&f->filelist; fl=*l; ){ if(fl->f == nil){ *l = (*l)->link; free(fl); }else l = &(*l)->link; } f->nxchild = 0;} voidclosefile(File *f){ if(decref(f) == 0){ f->tree->destroy(f); freefile(f); }} static voidnop(File*){} intremovefile(File *f){ File *fp; Filelist *fl; fp = f->parent; if(fp == nil){ werrstr("no parent"); closefile(f); return -1; } if(fp == f){ werrstr("cannot remove root"); closefile(f); return -1; } wlock(f); wlock(fp); if(f->nchild != 0){ werrstr("has children"); wunlock(fp); wunlock(f); closefile(f); return -1; } if(f->parent != fp){ werrstr("parent changed underfoot"); wunlock(fp); wunlock(f); closefile(f); return -1; } for(fl=fp->filelist; fl; fl=fl->link) if(fl->f == f) break; assert(fl != nil && fl->f == f); fl->f = nil; fp->nchild--; fp->nxchild++; f->parent = nil; wunlock(f); cleanfilelist(fp); wunlock(fp); closefile(fp); /* reference from child */ closefile(f); /* reference from tree */ closefile(f); return 0;} File*createfile(File *fp, char *name, char *uid, ulong perm, void *aux){ File *f; Filelist **l, *fl; Tree *t; if((fp->qid.type&QTDIR) == 0){ werrstr("create in non-directory"); return nil; } wlock(fp); /* * We might encounter blank spots along the * way due to deleted files that have not yet * been flushed from the file list. Don't reuse * those - some apps (e.g., omero) depend on * the file order reflecting creation order. * Always create at the end of the list. */ for(l=&fp->filelist; fl=*l; l=&fl->link){ if(fl->f && strcmp(fl->f->name, name) == 0){ wunlock(fp); werrstr("file already exists"); return nil; } } fl = emalloc9p(sizeof *fl); *l = fl; f = allocfile(); f->name = estrdup9p(name); f->uid = estrdup9p(uid ? uid : fp->uid); f->gid = estrdup9p(fp->gid); f->muid = estrdup9p(uid ? uid : "unknown"); f->aux = aux; f->mode = perm; t = fp->tree; lock(&t->genlock); f->qid.path = t->qidgen++; unlock(&t->genlock); if(perm & DMDIR) f->qid.type |= QTDIR; if(perm & DMAPPEND) f->qid.type |= QTAPPEND; if(perm & DMEXCL) f->qid.type |= QTEXCL; f->mode = perm; f->atime = f->mtime = time(0); f->length = 0; f->parent = fp; incref(fp); f->tree = fp->tree; incref(f); /* being returned */ incref(f); /* for the tree */ fl->f = f; fp->nchild++; wunlock(fp); return f;} static File*walkfile1(File *dir, char *elem){ File *fp; Filelist *fl; rlock(dir); if(strcmp(elem, "..") == 0){ fp = dir->parent; incref(fp); runlock(dir); closefile(dir); return fp; } fp = nil; for(fl=dir->filelist; fl; fl=fl->link) if(fl->f && strcmp(fl->f->name, elem)==0){ fp = fl->f; incref(fp); break; } runlock(dir); closefile(dir); return fp;} File*walkfile(File *f, char *path){ char *os, *s, *nexts; if(strchr(path, '/') == nil) return walkfile1(f, path); /* avoid malloc */ os = s = estrdup9p(path); for(; *s; s=nexts){ if(nexts = strchr(s, '/')) *nexts++ = '\0'; else nexts = s+strlen(s); f = walkfile1(f, s); if(f == nil) break; } free(os); return f;} Tree*alloctree(char *uid, char *gid, ulong mode, void (*destroy)(File*)){ char *muid; Tree *t; File *f; t = emalloc9p(sizeof *t); f = allocfile(); f->name = estrdup9p("/"); if(uid == nil){ uid = getuser(); if(uid == nil) uid = "none"; } uid = estrdup9p(uid); if(gid == nil) gid = estrdup9p(uid); else gid = estrdup9p(gid); muid = estrdup9p(uid); f->qid = (Qid){0, 0, QTDIR}; f->length = 0; f->atime = f->mtime = time(0); f->mode = DMDIR | mode; f->tree = t; f->parent = f; f->uid = uid; f->gid = gid; f->muid = muid; incref(f); t->root = f; t->qidgen = 0; t->dirqidgen = 1; if(destroy == nil) destroy = nop; t->destroy = destroy; return t;} static void_freefiles(File *f){ Filelist *fl, *flnext; for(fl=f->filelist; fl; fl=flnext){ flnext = fl->link; _freefiles(fl->f); free(fl); } f->tree->destroy(f); freefile(f);} voidfreetree(Tree *t){ _freefiles(t->root); free(t);} Readdir*opendirfile(File *dir){ Readdir *r; rlock(dir); if((dir->mode & DMDIR)==0){ runlock(dir); return nil; } r = emalloc9p(sizeof(*r)); /* * This reference won't go away while we're * using it because file list entries are not freed * until the directory is removed and all refs to * it (our fid is one!) have gone away. */ r->fl = dir->filelist; r->dir = dir; incref(&dir->readers); runlock(dir); return r;} longreaddirfile(Readdir *r, uchar *buf, long n){ long x, m; Filelist *fl; for(fl=r->fl, m=0; fl && m+2<=n; fl=fl->link, m+=x){ if(fl->f == nil) x = 0; else if((x=convD2M(fl->f, buf+m, n-m)) <= BIT16SZ) break; } r->fl = fl; return m;} voidclosedirfile(Readdir *r){ if(decref(&r->dir->readers) == 0){ wlock(r->dir); cleanfilelist(r->dir); wunlock(r->dir); } free(r);}
/*
* This file is part of the UCB release of Plan 9. It is subject to the license
* terms in the LICENSE file found in the top-level directory of this
* distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
* part of the UCB release of Plan 9, including this file, may be copied,
* modified, propagated, or distributed except according to the terms contained
* in the LICENSE file.
*/
#include <u.h>
#include <libc.h>
#include <auth.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>
/*
* To avoid deadlock, the following rules must be followed.
* Always lock child then parent, never parent then child.
* If holding the free file lock, do not lock any Files.
*/
struct Filelist
{
File *f;
Filelist *link;
};
struct Readdir
{
File *dir;
Filelist *fl;
};
static QLock filelk;
static File *freefilelist;
static File*
allocfile(void)
{
int i, a;
File *f;
enum { N = 16 };
qlock(&filelk);
if(freefilelist == nil){
f = emalloc9p(N*sizeof(*f));
for(i=0; i<N-1; i++)
f[i].aux = &f[i+1];
f[N-1].aux = nil;
f[0].allocd = 1;
freefilelist = f;
}
f = freefilelist;
freefilelist = f->aux;
qunlock(&filelk);
a = f->allocd;
memset(f, 0, sizeof *f);
f->allocd = a;
return f;
}
static void
freefile(File *f)
{
Filelist *fl, *flnext;
for(fl=f->filelist; fl; fl=flnext){
flnext = fl->link;
assert(fl->f == nil);
free(fl);
}
free(f->name);
free(f->uid);
free(f->gid);
free(f->muid);
qlock(&filelk);
assert(f->ref == 0);
f->aux = freefilelist;
freefilelist = f;
qunlock(&filelk);
}
static void
cleanfilelist(File *f)
{
Filelist **l;
Filelist *fl;
/*
* can't delete filelist structures while there
* are open readers of this directory, because
* they might have references to the structures.
* instead, just leave the empty refs in the list
* until there is no activity and then clean up.
*/
if(f->readers.ref != 0)
return;
if(f->nxchild == 0)
return;
/*
* no dir readers, file is locked, and
* there are empty entries in the file list.
* clean them out.
*/
for(l=&f->filelist; fl=*l; ){
if(fl->f == nil){
*l = (*l)->link;
free(fl);
}else
l = &(*l)->link;
}
f->nxchild = 0;
}
void
closefile(File *f)
{
if(decref(f) == 0){
f->tree->destroy(f);
freefile(f);
}
}
static void
nop(File*)
{
}
int
removefile(File *f)
{
File *fp;
Filelist *fl;
fp = f->parent;
if(fp == nil){
werrstr("no parent");
closefile(f);
return -1;
}
if(fp == f){
werrstr("cannot remove root");
closefile(f);
return -1;
}
wlock(f);
wlock(fp);
if(f->nchild != 0){
werrstr("has children");
wunlock(fp);
wunlock(f);
closefile(f);
return -1;
}
if(f->parent != fp){
werrstr("parent changed underfoot");
wunlock(fp);
wunlock(f);
closefile(f);
return -1;
}
for(fl=fp->filelist; fl; fl=fl->link)
if(fl->f == f)
break;
assert(fl != nil && fl->f == f);
fl->f = nil;
fp->nchild--;
fp->nxchild++;
f->parent = nil;
wunlock(f);
cleanfilelist(fp);
wunlock(fp);
closefile(fp); /* reference from child */
closefile(f); /* reference from tree */
closefile(f);
return 0;
}
File*
createfile(File *fp, char *name, char *uid, ulong perm, void *aux)
{
File *f;
Filelist **l, *fl;
Tree *t;
if((fp->qid.type&QTDIR) == 0){
werrstr("create in non-directory");
return nil;
}
wlock(fp);
/*
* We might encounter blank spots along the
* way due to deleted files that have not yet
* been flushed from the file list. Don't reuse
* those - some apps (e.g., omero) depend on
* the file order reflecting creation order.
* Always create at the end of the list.
*/
for(l=&fp->filelist; fl=*l; l=&fl->link){
if(fl->f && strcmp(fl->f->name, name) == 0){
wunlock(fp);
werrstr("file already exists");
return nil;
}
}
fl = emalloc9p(sizeof *fl);
*l = fl;
f = allocfile();
f->name = estrdup9p(name);
f->uid = estrdup9p(uid ? uid : fp->uid);
f->gid = estrdup9p(fp->gid);
f->muid = estrdup9p(uid ? uid : "unknown");
f->aux = aux;
f->mode = perm;
t = fp->tree;
lock(&t->genlock);
f->qid.path = t->qidgen++;
unlock(&t->genlock);
if(perm & DMDIR)
f->qid.type |= QTDIR;
if(perm & DMAPPEND)
f->qid.type |= QTAPPEND;
if(perm & DMEXCL)
f->qid.type |= QTEXCL;
f->mode = perm;
f->atime = f->mtime = time(0);
f->length = 0;
f->parent = fp;
incref(fp);
f->tree = fp->tree;
incref(f); /* being returned */
incref(f); /* for the tree */
fl->f = f;
fp->nchild++;
wunlock(fp);
return f;
}
static File*
walkfile1(File *dir, char *elem)
{
File *fp;
Filelist *fl;
rlock(dir);
if(strcmp(elem, "..") == 0){
fp = dir->parent;
incref(fp);
runlock(dir);
closefile(dir);
return fp;
}
fp = nil;
for(fl=dir->filelist; fl; fl=fl->link)
if(fl->f && strcmp(fl->f->name, elem)==0){
fp = fl->f;
incref(fp);
break;
}
runlock(dir);
closefile(dir);
return fp;
}
File*
walkfile(File *f, char *path)
{
char *os, *s, *nexts;
if(strchr(path, '/') == nil)
return walkfile1(f, path); /* avoid malloc */
os = s = estrdup9p(path);
for(; *s; s=nexts){
if(nexts = strchr(s, '/'))
*nexts++ = '\0';
else
nexts = s+strlen(s);
f = walkfile1(f, s);
if(f == nil)
break;
}
free(os);
return f;
}
Tree*
alloctree(char *uid, char *gid, ulong mode, void (*destroy)(File*))
{
char *muid;
Tree *t;
File *f;
t = emalloc9p(sizeof *t);
f = allocfile();
f->name = estrdup9p("/");
if(uid == nil){
uid = getuser();
if(uid == nil)
uid = "none";
}
uid = estrdup9p(uid);
if(gid == nil)
gid = estrdup9p(uid);
else
gid = estrdup9p(gid);
muid = estrdup9p(uid);
f->qid = (Qid){0, 0, QTDIR};
f->length = 0;
f->atime = f->mtime = time(0);
f->mode = DMDIR | mode;
f->tree = t;
f->parent = f;
f->uid = uid;
f->gid = gid;
f->muid = muid;
incref(f);
t->root = f;
t->qidgen = 0;
t->dirqidgen = 1;
if(destroy == nil)
destroy = nop;
t->destroy = destroy;
return t;
}
static void
_freefiles(File *f)
{
Filelist *fl, *flnext;
for(fl=f->filelist; fl; fl=flnext){
flnext = fl->link;
_freefiles(fl->f);
free(fl);
}
f->tree->destroy(f);
freefile(f);
}
void
freetree(Tree *t)
{
_freefiles(t->root);
free(t);
}
Readdir*
opendirfile(File *dir)
{
Readdir *r;
rlock(dir);
if((dir->mode & DMDIR)==0){
runlock(dir);
return nil;
}
r = emalloc9p(sizeof(*r));
/*
* This reference won't go away while we're
* using it because file list entries are not freed
* until the directory is removed and all refs to
* it (our fid is one!) have gone away.
*/
r->fl = dir->filelist;
r->dir = dir;
incref(&dir->readers);
runlock(dir);
return r;
}
long
readdirfile(Readdir *r, uchar *buf, long n)
{
long x, m;
Filelist *fl;
for(fl=r->fl, m=0; fl && m+2<=n; fl=fl->link, m+=x){
if(fl->f == nil)
x = 0;
else if((x=convD2M(fl->f, buf+m, n-m)) <= BIT16SZ)
break;
}
r->fl = fl;
return m;
}
void
closedirfile(Readdir *r)
{
if(decref(&r->dir->readers) == 0){
wlock(r->dir);
cleanfilelist(r->dir);
wunlock(r->dir);
}
free(r);
}