1 files changed, 120 insertions, 0 deletions
diff --git a/appl/cmd/lstar.b b/appl/cmd/lstar.b
new file mode 100644
index 00000000..fddd19d2
--- /dev/null
+++ b/appl/cmd/lstar.b
@@ -0,0 +1,120 @@
+implement lstar;
+
+include "sys.m";
+	sys: Sys;
+	print, sprint, fprint: import sys;
+	stdin, stderr: ref sys->FD;
+include "draw.m";
+
+TBLOCK: con 512;	# tar logical blocksize
+Header: adt{
+	name: string;
+	size: int;
+	mtime: int;
+	skip: int;
+};
+
+lstar: module{
+	init:   fn(nil: ref Draw->Context, nil: list of string);
+};
+
+Error(mess: string){
+	fprint(stderr,"lstar: %s: %r\n",mess);
+	exit;
+}
+
+
+NBLOCK: con 20;		# blocking factor for efficient read
+tarbuf := array[NBLOCK*TBLOCK] of byte;	# static buffer
+nblock := NBLOCK;			# how many blocks of data are in tarbuf
+recno := NBLOCK;			# how many blocks in tarbuf have been consumed
+getblock():array of byte{
+	if(recno>=nblock){
+		i := sys->read(stdin,tarbuf,TBLOCK*NBLOCK);
+		if(i==0)
+			return tarbuf[0:0];
+		if(i<0)
+			Error("read error");
+		if(i%TBLOCK!=0)
+			Error("blocksize error");
+		nblock = i/TBLOCK;
+		recno = 0;
+	}
+	recno++;
+	return tarbuf[(recno-1)*TBLOCK:recno*TBLOCK];
+}
+
+octal(b:array of byte):int{
+	sum := 0;
+	for(i:=0; i<len b; i++){
+		bi := int b[i];
+		if(bi==' ') continue;
+		if(bi==0) break;
+		sum = 8*sum + bi-'0';
+	}
+	return sum;
+}
+
+nullterm(b:array of byte):string{
+	for(i:=0; i<len b; i++)
+		if(b[i]==byte 0) break;
+	return string b[0:i];
+}
+
+getdir():ref Header{
+	dblock := getblock();
+	if(len dblock==0)
+		return nil;
+	if(dblock[0]==byte 0)
+		return nil;
+
+	name := nullterm(dblock[0:100]);
+	if(int dblock[345]!=0)
+		name = nullterm(dblock[345:500])+"/"+name;
+
+	magic := string(dblock[257:262]);
+	if(magic[0]!=0 && magic!="ustar")
+		Error("bad magic "+name);
+	chksum := octal(dblock[148:156]);
+	for(ci:=148; ci<156; ci++) dblock[ci] = byte ' ';
+	for(i:=0; i<TBLOCK; i++)
+		chksum -= int dblock[i];
+	if(chksum!=0)
+		Error("directory checksum error "+name);
+
+	skip := 1;
+	size := 0;
+	mtime := 0;
+	case int dblock[156]{
+	'0' or '5' or '7' or 0 =>
+		skip = 0;
+		size = octal(dblock[124:136]);
+		mtime = octal(dblock[136:148]);
+	'1' =>
+		fprint(stderr,"skipping link %s -> %s\n",name,string(dblock[157:257]));
+	'2' or 's' =>
+		fprint(stderr,"skipping symlink %s\n",name);
+	'3' or '4' or '6' =>
+		fprint(stderr,"skipping special file %s\n",name);
+	* =>
+		Error(sprint("unrecognized typeflag %d for %s",int dblock[156],name));
+	}
+	return ref Header(name,size,mtime,skip);
+}
+
+
+init(nil: ref Draw->Context, nil: list of string){
+	sys = load Sys Sys->PATH;
+	stdin = sys->fildes(0);
+	stderr = sys->fildes(2);
+	ofile: ref sys->FD;
+
+	while((file := getdir())!=nil){
+		bytes := file.size;
+		blocks := (bytes+TBLOCK-1)/TBLOCK;
+		for(; blocks>0; blocks--)
+			getblock();
+		print("%s %d %d 0\n",file.name,file.mtime,file.size);
+		ofile = nil;
+	}
+}