9660srv: import from Plan 9

src/cmd/9660srv/xfile.c

@@ -0,0 +1,170 @@
+#include <u.h>
+#include <libc.h>
+#include <auth.h>
+#include <fcall.h>
+#include "dat.h"
+#include "fns.h"
+
+static Xfile*	clean(Xfile*);
+
+#define	FIDMOD	127	/* prime */
+
+static Xdata*	xhead;
+static Xfile*	xfiles[FIDMOD];
+static Xfile*	freelist;
+
+Xdata*
+getxdata(char *name)
+{
+	int fd;
+	Dir *dir;
+	Xdata *xf, *fxf;
+	int flag;
+
+	if(name[0] == 0)
+		name = deffile;
+	if(name == 0)
+		error(Enofile);
+	flag = (access(name, 6) == 0) ? ORDWR : OREAD;
+	fd = open(name, flag);
+	if(fd < 0)
+		error(Enonexist);
+	dir = nil;
+	if(waserror()){
+		close(fd);
+		free(dir);
+		nexterror();
+	}
+	if((dir = dirfstat(fd)) == nil)
+		error("I/O error");
+	if((dir->qid.type & ~QTTMP) != QTFILE)
+		error("attach name not a plain file");
+	for(fxf=0,xf=xhead; xf; xf=xf->next){
+		if(xf->name == 0){
+			if(fxf == 0)
+				fxf = xf;
+			continue;
+		}
+		if(xf->qid.path != dir->qid.path || xf->qid.vers != dir->qid.vers)
+			continue;
+		if(xf->type != dir->type || xf->fdev != dir->dev)
+			continue;
+		xf->ref++;
+		chat("incref=%d, \"%s\", dev=%d...", xf->ref, xf->name, xf->dev);
+		close(fd);
+		poperror();
+		free(dir);
+		return xf;
+	}
+	if(fxf==0){
+		fxf = ealloc(sizeof(Xfs));
+		fxf->next = xhead;
+		xhead = fxf;
+	}
+	chat("alloc \"%s\", dev=%d...", name, fd);
+	fxf->ref = 1;
+	fxf->name = strcpy(ealloc(strlen(name)+1), name);
+	fxf->qid = dir->qid;
+	fxf->type = dir->type;
+	fxf->fdev = dir->dev;
+	fxf->dev = fd;
+	free(dir);
+	poperror();
+	return fxf;
+}
+
+static void
+putxdata(Xdata *d)
+{
+	if(d->ref <= 0)
+		panic(0, "putxdata");
+	d->ref--;
+	chat("decref=%d, \"%s\", dev=%d...", d->ref, d->name, d->dev);
+	if(d->ref == 0){
+		chat("purgebuf...");
+		purgebuf(d);
+		close(d->dev);
+		free(d->name);
+		d->name = 0;
+	}
+}
+
+void
+refxfs(Xfs *xf, int delta)
+{
+	xf->ref += delta;
+	if(xf->ref == 0){
+		if(xf->d)
+			putxdata(xf->d);
+		if(xf->ptr)
+			free(xf->ptr);
+		free(xf);
+	}
+}
+
+Xfile*
+xfile(int fid, int flag)
+{
+	int k = fid%FIDMOD;
+	Xfile **hp=&xfiles[k], *f, *pf;
+
+	for(f=*hp,pf=0; f; pf=f,f=f->next)
+		if(f->fid == fid)
+			break;
+	if(f && pf){
+		pf->next = f->next;
+		f->next = *hp;
+		*hp = f;
+	}
+	switch(flag){
+	default:
+		panic(0, "xfile");
+	case Asis:
+		if(f == 0)
+			error("unassigned fid");
+		return f;
+	case Clean:
+		break;
+	case Clunk:
+		if(f){
+			*hp = f->next;
+			clean(f);
+			f->next = freelist;
+			freelist = f;
+		}
+		return 0;
+	}
+	if(f)
+		return clean(f);
+	if(f = freelist)	/* assign = */
+		freelist = f->next;
+	else
+		f = ealloc(sizeof(Xfile));
+	f->next = *hp;
+	*hp = f;
+	f->xf = 0;
+	f->fid = fid;
+	f->flags = 0;
+	f->qid = (Qid){0,0,0};
+	f->len = 0;
+	f->ptr = 0;
+	return f;
+}
+
+static Xfile *
+clean(Xfile *f)
+{
+	if(f->xf){
+		refxfs(f->xf, -1);
+		f->xf = 0;
+	}
+	if(f->len){
+		free(f->ptr);
+		f->len = 0;
+	}
+	f->ptr = 0;
+	f->flags = 0;
+	f->qid = (Qid){0,0,0};
+	return f;
+}
+