# Structure FileSys

Identifier index | Structure index
--- | ---

    (* OS.FileSys -- SML Basis Library *)

    type dirstream

    val openDir   : string -> dirstream
    val readDir   : dirstream -> string option
    val rewindDir : dirstream -> unit
    val closeDir  : dirstream -> unit

    val chDir     : string -> unit
    val getDir    : unit -> string
    val mkDir     : string -> unit
    val rmDir     : string -> unit
    val isDir     : string -> bool

    val realPath  : string -> string
    val fullPath  : string -> string
    val isLink    : string -> bool
    val readLink  : string -> string

    val modTime   : string -> Time.time
    val setTime   : string * Time.time option -> unit
    val remove    : string -> unit
    val rename    : {old: string, new: string} -> unit

    datatype access = A_READ | A_WRITE | A_EXEC
    val access    : string * access list -> bool

    val fileSize  : string -> int

    val tmpName   : unit -> string

    eqtype file_id
    val fileId    : string -> file_id
    val hash      : file_id -> word
    val compare   : file_id * file_id -> order

    (*
       These functions operate on the file system.  They raise OS.SysErr
       in case of errors.

       [openDir p] opens directory p and returns a directory stream for
       use by readDir, rewindDir, and closeDir.  Subsequent calls to
       readDir will return the directory entries in some unspecified
       order.

       [readDir dstr] returns SOME(s), consuming an entry s from the
       directory stream if it is non-empty; returns NONE if it is empty
       (when all directory entries have been read).  Only entries distinct
       from the parent arc and the current arc (that is, .. and . in Unix,
       DOS, and Windows; see the Path structure) will be returned.

       [rewindDir dstr] resets the directory stream as if it had just been
       opened.

       [closeDir dstr] closes the directory stream.  All subsequent
       operations on the stream will raise OS.SysErr.

       [chDir p] changes the current working directory to p.  This affects
       calls to the functions use, load, compile in the interactive
       system, as well as all functions defined in this library.  If p
       specifies a volume name, then this command also changes the current
       volume (relevant under DOS, Windows, OS/2, etc.).

       [getDir ()] returns the name of the current working directory.

       [mkDir p] creates directory p on the file system.

       [rmDir p] removes directory p from the file system.

       [isDir p] tests whether p is a directory.

       [fullPath p] returns a canonical form of path p, where all
       occurrences of the arcs ".", "..", "" have been expanded or
       removed, and (under Unix) symbolic links have been fully expanded.
       Raises SysErr if a directory on the path, or the file or directory
       named, does not exist or is not accessible, or if there is a link
       loop.

       [realPath p] behaves as fullPath(p) if p is absolute.  If p is
       relative and on the same volume as the current working directory,
       it returns a canonical path relative to the current working
       directory, where superfluous occurrences of the arcs ".", "..", ""
       have been removed, and (under Unix) symbolic links have been fully
       expanded.  Raises SysErr if a directory on the path, or the file or
       directory named, does not exist or is not accessible, or if there
       is a link loop.  Raises Path if p is relative and on a different
       volume than the current working directory.

       [isLink p] returns true if p names a symbolic link.  Raises SysErr
       if the file does not exist or there is an access violation.  On
       operating systems without symbolic links, it returns false, or
       raises SysErr if the file does not exist or there is an access
       violation.

       [readLink p] returns the contents of the symbolic link p.  Raises
       SysErr if p does not exist or is not a symbolic link, or there is
       an access violation.  On operating systems without symbolic links,
       it raises SysErr.

       [modTime p] returns the modification time of file p.

       [setTime (p, tmopt)] sets the modification and access time of file
       p.  If tmopt is SOME t, then the time t is used; otherwise the
       current time, that is, Time.now(), is used.

       [remove p] deletes file p from the file system.

       [rename {old, new}] changes the name of file `old' to `new'.

       [access] is the type of access permissions:

       [A_READ] specifies read access.

       [A_WRITE] specifies write access.

       [A_EXEC] specifies permission to execute the file (or directory).

       [access (p, accs)] tests the access permissions of file p,
       expanding symbolic links as necessary.  If the list accs of
       required access permission is empty, it tests whether p exists.  If
       accs contains A_READ, A_WRITE, or A_EXEC, respectively, it tests
       whether the user process has read, write, or execute permission for
       the file.
           Under Unix, the access test is done with the `real' user
       id and group id (as opposed to the `effective' user id and group
       id) of the user process.  Hence access("file", [A_READ]) may return
       false, yet the file may be readable by the process, in case the
       effective user id or group id has been changed by setuid.

       [fileSize p] return the size, in bytes, of the file p.  Raises SysErr
       if p does not exist or its directory is not accessible.

       [tmpName ()] returns a file name suitable for creating a fresh
       temporary file.  Note that there is no guarantee that the file name
       will be unique, since a file of that name may be created between
       the call to tmpName and a subsequent call to openOut which creates
       the file.  The file name will be absolute, usually of the form
       /tmp/xxxxxxxx provided by POSIX tmpnam (3).

       [file_id] is the type of unique identities of file system objects
       (including device ids and volume ids, but possibly insensitive to
       volume changes on removable volumes, such as tapes and diskettes).
       The set of file ids is equipped with a total linear order.

       [fileId p] returns the file_id of the file system object named by
       path p.  It holds that fileId p1 = fileId p2 if and only if p1 and
       p2 name the same file system object.

       [hash fid] returns a hashvalue for fid, suitable for use in a
       hashtable of file ids (and hence files).
       If fid1 = fid2 then hash fid1 = hash fid2.

       [compare (fid1, fid2)] returns LESS, EQUAL, or GREATER, according
       as fid1 precedes, equals, or follows fid2 in the total linear order
       on file ids.  This is suitable for e.g. an ordered binary tree of
       file ids (and hence files).
    *)

Identifier index | Structure index
--- | ---

Moscow ML 2.00