LINUX386.FileDir.Mod.txt

MODULE FileDir;   (*NW 12.1.86 / 23.8.90 / 15.8.2013*)
  IMPORT SYSTEM, Kernel;

  CONST FnLength*    = 32;
        SecTabSize*   = 64;
        ExTabSize*   = 12;
        SectorSize*   = 1024;
        IndexSize*   = SectorSize DIV 4;
        HeaderSize*  = 352;
        DirRootAdr*  = 29;
        DirPgSize*   = 24;
        DirMark*    = 9B1EA38DH;
        HeaderMark* = 9BA71D86H;
        FillerSize = 52;

  TYPE DiskAdr      = INTEGER;
    FileName*       = ARRAY FnLength OF CHAR;
    SectorTable*    = ARRAY SecTabSize OF DiskAdr;
    ExtensionTable* = ARRAY ExTabSize OF DiskAdr;
    EntryHandler*   = PROCEDURE (name: FileName; sec: DiskAdr; VAR continue: BOOLEAN);

    FileHeader* =
      RECORD (*first page of each file on disk*)
        mark*: INTEGER;
        name*: FileName;
        aleng*, bleng*, date*: INTEGER;
        ext*:  ExtensionTable;
        sec*: SectorTable;
        fill: ARRAY SectorSize - HeaderSize OF BYTE;
      END ;

    FileHd* = POINTER TO FileHeader;
    IndexSector* = ARRAY IndexSize OF DiskAdr;
    DataSector* = ARRAY SectorSize OF BYTE;

    DirEntry* =  (*B-tree node*)
      RECORD
        name*: FileName;
        adr*:  DiskAdr; (*sec no of file header*)
        p*:    DiskAdr  (*sec no of descendant in directory*)
      END ;

    DirPage*  =
      RECORD mark*:  INTEGER;
        m*:     INTEGER;
        p0*:    DiskAdr;  (*sec no of left descendant in directory*)
        fill:  ARRAY FillerSize OF BYTE;
        e*:  ARRAY DirPgSize OF DirEntry
      END ;

  VAR fd: INTEGER;
    syscall2: PROCEDURE (eax, ebx: INTEGER): INTEGER;
    syscall3: PROCEDURE (eax, ebx, ecx: INTEGER): INTEGER;
    syscall4: PROCEDURE (eax, ebx, ecx, edx: INTEGER): INTEGER;

  PROCEDURE Check(s: ARRAY OF CHAR): INTEGER;
    VAR i, res: INTEGER; ch: CHAR;
  BEGIN ch := s[0]; i := 0;
    IF (ch >= "A") & (ch <= "Z") OR (ch >= "a") & (ch <= "z") THEN
      REPEAT INC(i); ch := s[i]
      UNTIL ~((ch >= "0") & (ch <= "9") OR (ch >= "A") & (ch <= "Z")
        OR (ch >= "a") & (ch <= "z") OR (ch = ".")) OR (i = FnLength);
      IF i = FnLength THEN res := 4
      ELSIF ch = 0X THEN res := 0;
        WHILE i < FnLength DO INC(i) END
      ELSE res := 5
      END
    ELSIF ch = 0X THEN res := -1
    ELSE res := 3
    END;
    RETURN res
  END Check;

  (*Exported procedures: Search, Insert, Delete, Enumerate, Init*)

  PROCEDURE Search*(name: FileName; VAR A: DiskAdr);
    VAR res: INTEGER;
  BEGIN A := 0;
    IF Check(name) = 0 THEN (* access(name, R_OK|W_OK) *)
      REPEAT res := syscall3(33, SYSTEM.ADR(name), 6) UNTIL res # -4;
      IF res = 0 THEN A := -1 END
    END
  END Search;

  PROCEDURE Insert*(name: FileName; fad: DiskAdr);
  BEGIN ASSERT(FALSE)
  END Insert;

  PROCEDURE Delete*(name: FileName; VAR fad: DiskAdr);
    VAR res: INTEGER;
  BEGIN fad := 0;
    IF Check(name) = 0 THEN
      REPEAT res := syscall2(10, SYSTEM.ADR(name)) UNTIL res # -4; (*unlink*)
      IF res = 0 THEN fad := -1 END
    END
  END Delete;

  PROCEDURE Enumerate*(prefix: ARRAY OF CHAR; proc: EntryHandler);
    CONST MaxEnt = 1024;
    VAR res, i, j: INTEGER; pfx, nmx: CHAR;
      buf: ARRAY MaxEnt OF CHAR;
      continue: BOOLEAN;
      name: FileName; 
  BEGIN
    IF fd > 0 THEN (*close*)
      REPEAT res := syscall2(6, fd) UNTIL res # -4;
      fd := -1
    END;
    IF Check(prefix) <= 0 THEN (* open(".", O_DIRECTORY | O_RDONLY,  0) *)
      REPEAT fd := syscall4(5, SYSTEM.ADR("."), 10000H, 0) UNTIL fd # -4; 
      IF fd >= 0 THEN
        continue := TRUE;
        REPEAT
          REPEAT res := syscall4(220, fd, SYSTEM.ADR(buf), MaxEnt) UNTIL res # -4; (*getdents64*)
          IF res > 0 THEN (*ok*)
            j := 0;
            REPEAT
              IF buf[j+18] = 8X THEN (*regular file*)
                i := 0;
                REPEAT nmx := buf[j+i+19]; name[i] := nmx; pfx := prefix[i]; INC(i)
                UNTIL (pfx # nmx) OR (nmx = 0X) OR (i >= FnLength);
                IF (pfx = 0X) & ((nmx = 0X) OR (i < FnLength)) THEN (*match prefix, fit into buffer*)
                  WHILE (nmx # 0X) & (i < FnLength) DO nmx := buf[j+i+19]; name[i] := nmx; INC(i) END;
                  IF (nmx = 0X) & (Check(name) = 0) THEN (*name copied and valid*)
                    proc(name, -1, continue)
                  END
                END
              END;
              INC(j, ORD(buf[j+17])*100H + ORD(buf[j+16]))
            UNTIL j >= res
          END
        UNTIL ~continue OR (res <= 0);
        REPEAT res := syscall2(6, fd) UNTIL res # -4; fd := -1 (*close*)
      END
    END
  END Enumerate;

(* ----- initialization ----- *)

PROCEDURE Init*;
  BEGIN fd := -1;
    SYSTEM.PUT(SYSTEM.ADR(syscall2), SYSTEM.ADR($8B442408 8B5C2404 CD80 C20800 6690 90$));
    SYSTEM.PUT(SYSTEM.ADR(syscall3), SYSTEM.ADR($8B44240C 8B5C2408 8B4C2404 CD80 C20C00 6690 90$));
    SYSTEM.PUT(SYSTEM.ADR(syscall4), SYSTEM.ADR($8B442410 8B5C240C 8B4C2408 8B542404 CD80 C21000 6690 90$));
  END Init; 
  
END FileDir.