tapefs from plan9

src/cmd/tapefs/tapfs.c

@@ -0,0 +1,115 @@
+#include <u.h>
+#include <libc.h>
+#include "tapefs.h"
+
+/*
+ * File system for old tap tapes.
+ */
+
+struct tap {
+	unsigned char	name[32];
+	unsigned char	mode[1];
+	unsigned char	uid[1];
+	unsigned char	size[2];
+	unsigned char	tmod[4];
+	unsigned char	taddress[2];
+	unsigned char	unused[20];
+	unsigned char	checksum[2];
+} dir[192];
+
+int	tapefile;
+char	buffer[8192];
+long	cvtime(unsigned char *);
+extern	int verbose;
+extern	int newtap;
+
+void
+populate(char *name)
+{
+	int i, isabs;
+	struct tap *tpp;
+	Fileinf f;
+
+	replete = 1;
+	tapefile = open(name, OREAD);
+	if (tapefile<0)
+		error("Can't open argument file");
+	read(tapefile, dir, sizeof dir);
+	for (i=0, tpp=&dir[8]; i<192; i++, tpp++) {
+		unsigned char *sp = (unsigned char *)tpp;
+		int j, cksum = 0;
+		for (j=0; j<32; j++, sp+=2)
+			cksum += sp[0] + (sp[1]<<8);
+		cksum &= 0xFFFF;
+		if (cksum!=0) {
+			print("cksum failure\n");
+			continue;
+		}
+		if (tpp->name[0]=='\0')
+			continue;
+		f.addr = tpp->taddress[0] + (tpp->taddress[1]<<8);
+		if (f.addr==0)
+			continue;
+		f.size = tpp->size[0] + (tpp->size[1]<<8);
+		f.mdate = cvtime(tpp->tmod);
+		f.mode = tpp->mode[0]&0777;
+		f.uid = tpp->uid[0]&0377;
+		isabs = tpp->name[0]=='/';
+		f.name = (char *)tpp->name+isabs;
+		if (verbose)
+			print("%s mode %o uid %d, %s", f.name, f.mode, f.uid, ctime(f.mdate));
+		poppath(f, 1);
+	}
+}
+
+long
+cvtime(unsigned char *tp)
+{
+	unsigned long t = (tp[1]<<24)+(tp[0]<<16)+(tp[3]<<8)+(tp[2]<<0);
+	if (!newtap) {
+		t /= 60;
+		t += 3*365*24*3600;
+	}
+	return t;
+}
+
+void
+popdir(Ram *r)
+{
+	USED(r);
+}
+
+void
+dotrunc(Ram *r)
+{
+	USED(r);
+}
+
+void
+docreate(Ram *r)
+{
+	USED(r);
+}
+
+char *
+doread(Ram *r, vlong off, long cnt)
+{
+	if (cnt>sizeof(buffer))
+		print("count too big\n");
+	seek(tapefile, 512*r->addr+off, 0);
+	read(tapefile, buffer, cnt);
+	return buffer;
+}
+
+void
+dowrite(Ram *r, char *buf, long off, long cnt)
+{
+	USED(r); USED(buf); USED(off); USED(cnt);
+}
+
+int
+dopermw(Ram *r)
+{
+	USED(r);
+	return 0;
+}