ref: 1018d7a7091fd5e0433f501a3474cdc3fec322cc
dir: /appl/cmd/lstar.b/
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; } }