1 files changed, 144 insertions, 0 deletions
diff --git a/src/cmd/tapefs/tarfs.c b/src/cmd/tapefs/tarfs.c
new file mode 100644
index 00000000..5bbd8b9c
--- /dev/null
+++ b/src/cmd/tapefs/tarfs.c
@@ -0,0 +1,144 @@
+#include <u.h>
+#include <libc.h>
+#include <auth.h>
+#include <fcall.h>
+#include "tapefs.h"
+
+/*
+ * File system for tar tapes (read-only)
+ */
+
+#define TBLOCK	512
+#define NBLOCK	40	/* maximum blocksize */
+#define DBLOCK	20	/* default blocksize */
+#define TNAMSIZ	100
+
+union hblock {
+	char dummy[TBLOCK];
+	char tbuf[Maxbuf];
+	struct header {
+		char name[TNAMSIZ];
+		char mode[8];
+		char uid[8];
+		char gid[8];
+		char size[12];
+		char mtime[12];
+		char chksum[8];
+		char linkflag;
+		char linkname[TNAMSIZ];
+	} dbuf;
+} dblock;
+
+int	tapefile;
+int	checksum(void);
+
+void
+populate(char *name)
+{
+	long blkno, isabs, chksum, linkflg;
+	Fileinf f;
+
+	tapefile = open(name, OREAD);
+	if (tapefile<0)
+		error("Can't open argument file");
+	replete = 1;
+	for (blkno = 0;;) {
+		seek(tapefile, TBLOCK*blkno, 0);
+		if (read(tapefile, dblock.dummy, sizeof(dblock.dummy))<sizeof(dblock.dummy))
+			break;
+		if (dblock.dbuf.name[0]=='\0')
+			break;
+		f.addr = blkno+1;
+		f.mode = strtoul(dblock.dbuf.mode, 0, 8);
+		f.uid = strtoul(dblock.dbuf.uid, 0, 8);
+		f.gid = strtoul(dblock.dbuf.gid, 0, 8);
+		if((uchar)dblock.dbuf.size[0] == 0x80)
+			f.size = g8byte(dblock.dbuf.size+3);
+		else
+			f.size = strtoull(dblock.dbuf.size, 0, 8);
+		f.mdate = strtoul(dblock.dbuf.mtime, 0, 8);
+		chksum = strtoul(dblock.dbuf.chksum, 0, 8);
+		/* the mode test is ugly but sometimes necessary */
+		if (dblock.dbuf.linkflag == '5'
+		|| (f.mode&0170000) == 040000
+		||  strrchr(dblock.dbuf.name, '\0')[-1] == '/'){
+			f.mode |= DMDIR;
+			f.size = 0;
+		}
+		f.mode &= DMDIR|0777;
+		linkflg = dblock.dbuf.linkflag=='s' || dblock.dbuf.linkflag=='1';
+		isabs = dblock.dbuf.name[0]=='/';
+		if (chksum != checksum()){
+			fprint(1, "bad checksum on %.28s\n", dblock.dbuf.name);
+			exits("checksum");
+		}
+		if (linkflg) {
+			/*fprint(2, "link %s->%s skipped\n", dblock.dbuf.name,
+			   dblock.dbuf.linkname);*/
+			f.size = 0;
+			blkno += 1;
+			continue;
+		}
+		f.name = dblock.dbuf.name+isabs;
+		if (f.name[0]=='\0')
+			fprint(1, "null name skipped\n");
+		else
+			poppath(f, 1);
+		blkno += 1 + (f.size+TBLOCK-1)/TBLOCK;
+	}
+}
+
+void
+dotrunc(Ram *r)
+{
+	USED(r);
+}
+
+void
+docreate(Ram *r)
+{
+	USED(r);
+}
+
+char *
+doread(Ram *r, vlong off, long cnt)
+{
+	seek(tapefile, TBLOCK*r->addr+off, 0);
+	if (cnt>sizeof(dblock.tbuf))
+		error("read too big");
+	read(tapefile, dblock.tbuf, cnt);
+	return dblock.tbuf;
+}
+
+void
+popdir(Ram *r)
+{
+	USED(r);
+}
+
+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;
+}
+
+int
+checksum()
+{
+	int i;
+	char *cp;
+
+	for (cp = dblock.dbuf.chksum; cp < &dblock.dbuf.chksum[sizeof(dblock.dbuf.chksum)]; cp++)
+		*cp = ' ';
+	i = 0;
+	for (cp = dblock.dummy; cp < &dblock.dummy[TBLOCK]; cp++)
+		i += *cp&0xff;
+	return(i);
+}