tapefs from plan9

src/cmd/tapefs/cpiofs.c

@@ -0,0 +1,139 @@
+#include <u.h>
+#include <libc.h>
+#include <auth.h>
+#include <fcall.h>
+#include "tapefs.h"
+
+/*
+ * File system for cpio 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 magic[6];
+		char dev[6];
+		char ino[6];
+		char mode[6];
+		char uid[6];
+		char gid[6];
+		char nlink[6];
+		char rdev[6];
+		char mtime[11];
+		char namesize[6];
+		char size[11];
+	} dbuf;
+	struct hname {
+		struct	header x;
+		char	name[1];
+	} nbuf;
+} dblock;
+
+int	tapefile;
+vlong	getoct(char*, int);
+
+void
+populate(char *name)
+{
+	vlong offset;
+	long isabs, magic, namesize, mode;
+	Fileinf f;
+
+	tapefile = open(name, OREAD);
+	if (tapefile<0)
+		error("Can't open argument file");
+	replete = 1;
+	for (offset = 0;;) {
+		seek(tapefile, offset, 0);
+		if (read(tapefile, (char *)&dblock.dbuf, TBLOCK)<TBLOCK)
+			break;
+		magic = getoct(dblock.dbuf.magic, sizeof(dblock.dbuf.magic));
+		if (magic != 070707){
+			print("%lo\n", magic);
+			error("out of phase--get help");
+		}
+		if (dblock.nbuf.name[0]=='\0' || strcmp(dblock.nbuf.name, "TRAILER!!!")==0)
+			break;
+		mode = getoct(dblock.dbuf.mode, sizeof(dblock.dbuf.mode));
+		f.mode = mode&0777;
+		switch(mode & 0170000) {
+		case 0040000:
+			f.mode |= DMDIR;
+			break;
+		case 0100000:
+			break;
+		default:
+			f.mode = 0;
+			break;
+		}
+		f.uid = getoct(dblock.dbuf.uid, sizeof(dblock.dbuf.uid));
+		f.gid = getoct(dblock.dbuf.gid, sizeof(dblock.dbuf.gid));
+		f.size = getoct(dblock.dbuf.size, sizeof(dblock.dbuf.size));
+		f.mdate = getoct(dblock.dbuf.mtime, sizeof(dblock.dbuf.mtime));
+		namesize = getoct(dblock.dbuf.namesize, sizeof(dblock.dbuf.namesize));
+		f.addr = offset+sizeof(struct header)+namesize;
+		isabs = dblock.nbuf.name[0]=='/';
+		f.name = &dblock.nbuf.name[isabs];
+		poppath(f, 1);
+		offset += sizeof(struct header)+namesize+f.size;
+	}
+}
+
+vlong
+getoct(char *p, int l)
+{
+	vlong r;
+
+	for (r=0; l>0; p++, l--){
+		r <<= 3;
+		r += *p-'0';
+	}
+	return r;
+}
+
+void
+dotrunc(Ram *r)
+{
+	USED(r);
+}
+
+void
+docreate(Ram *r)
+{
+	USED(r);
+}
+
+char *
+doread(Ram *r, vlong off, long cnt)
+{
+	seek(tapefile, 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;
+}