#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;}; 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);} 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(fp);	wlock(f);	if(f->nchild != 0){		werrstr("has children");		wunlock(f);		wunlock(fp);		closefile(f);		return -1;	} 	if(f->parent != fp){		werrstr("parent changed underfoot");		wunlock(f);		wunlock(fp);		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--;	f->parent = nil;	wunlock(fp);	wunlock(f); 	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 *fl, *freel;	Tree *t; 	if((fp->qid.type&QTDIR) == 0){		werrstr("create in non-directory");		return nil;	} 	freel = nil;	wlock(fp);	for(fl=fp->filelist; fl; fl=fl->link){		if(fl->f == nil)			freel = fl;		else if(strcmp(fl->f->name, name) == 0){			wunlock(fp);			werrstr("file already exists");			return nil;		}	} 	if(freel == nil){		freel = emalloc9p(sizeof *freel);		freel->link = fp->filelist;		fp->filelist = freel;	} 	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 */	freel->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;	File *nf; 	if(strchr(path, '/') == nil)		return walkfile1(f, path);	/* avoid malloc */ 	os = s = estrdup9p(path);	incref(f);	for(; *s; s=nexts){		if(nexts = strchr(s, '/'))			*nexts++ = '\0';		else			nexts = s+strlen(s);		nf = walkfile1(f, s);		decref(f);		f = nf;		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){		if(uid = getuser())			uid = estrdup9p(uid);	}	if(uid == nil)		uid = estrdup9p("none");	else		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);} struct Readdir {	Filelist *fl;}; 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	 * since we are dir->rdir.	 */	r->fl = dir->filelist;	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){	free(r);}