NAME
    Convert::UUlib - decode uu/xx/b64/mime/yenc/etc-encoded data from a
    massive number of files

SYNOPSIS
     use Convert::UUlib ':all';
 
     # read all the files named on the commandline and decode them
     # into the CURRENT directory. See below for a longer example.
     LoadFile $_ for @ARGV;

     for my $uu (GetFileList) {
        if ($uu->state & FILE_OK) {
          $uu->decode;
          print $uu->filename, "\n";
        }
     }

DESCRIPTION
    This module started as an interface to the uulib/uudeview library by
    Frank Pilhofer that can be used to decode all kinds of usenet (and
    other) binary messages.

    After upstream abondoned the project, th library was continuously
    bugfixed and improved in this module, with major focuses on security
    fixes, correctness and speed (that does not mean that this library is
    considered safe with untrusted data, but it surely is safer than the
    poriginal uudeview).

    Read the file doc/library.pdf from the distribution for in-depth
    information about the C-library used in this interface, and the rest of
    this document and especially the non-trivial decoder program at the end.

EXPORTED CONSTANTS
  Action code constants
      ACT_IDLE      we don't do anything
      ACT_SCANNING  scanning an input file
      ACT_DECODING  decoding into a temp file
      ACT_COPYING   copying temp to target
      ACT_ENCODING  encoding a file

  Message severity levels
      MSG_MESSAGE   just a message, nothing important
      MSG_NOTE      something that should be noticed
      MSG_WARNING   important msg, processing continues
      MSG_ERROR     processing has been terminated
      MSG_FATAL     decoder cannot process further requests
      MSG_PANIC     recovery impossible, app must terminate

  Options
      OPT_VERSION   version number MAJOR.MINORplPATCH (ro)
      OPT_FAST      assumes only one part per file
      OPT_DUMBNESS  switch off the program's intelligence
      OPT_BRACKPOL  give numbers in [] higher precendence
      OPT_VERBOSE   generate informative messages
      OPT_DESPERATE try to decode incomplete files
      OPT_IGNREPLY  ignore RE:plies (off by default)
      OPT_OVERWRITE whether it's OK to overwrite ex. files
      OPT_SAVEPATH  prefix to save-files on disk
      OPT_IGNMODE   ignore the original file mode
      OPT_DEBUG     print messages with FILE/LINE info
      OPT_ERRNO     get last error code for RET_IOERR (ro)
      OPT_PROGRESS  retrieve progress information
      OPT_USETEXT   handle text messages
      OPT_PREAMB    handle Mime preambles/epilogues
      OPT_TINYB64   detect short B64 outside of Mime
      OPT_ENCEXT    extension for single-part encoded files
      OPT_REMOVE    remove input files after decoding (dangerous)
      OPT_MOREMIME  strict MIME adherence
      OPT_DOTDOT    ".."-unescaping has not yet been done on input files
      OPT_RBUF      set default read I/O buffer size in bytes
      OPT_WBUF      set default write I/O buffer size in bytes
      OPT_AUTOCHECK automatically check file list after every loadfile

  Result/Error codes
      RET_OK        everything went fine
      RET_IOERR     I/O Error - examine errno
      RET_NOMEM     not enough memory
      RET_ILLVAL    illegal value for operation
      RET_NODATA    decoder didn't find any data
      RET_NOEND     encoded data wasn't ended properly
      RET_UNSUP     unsupported function (encoding)
      RET_EXISTS    file exists (decoding)
      RET_CONT      continue -- special from ScanPart
      RET_CANCEL    operation canceled

  File States
     This code is zero, i.e. "false":

      UUFILE_READ   Read in, but not further processed

     The following state codes are or'ed together:

      FILE_MISPART  Missing Part(s) detected
      FILE_NOBEGIN  No 'begin' found
      FILE_NOEND    No 'end' found
      FILE_NODATA   File does not contain valid uudata
      FILE_OK       All Parts found, ready to decode
      FILE_ERROR    Error while decoding
      FILE_DECODED  Successfully decoded
      FILE_TMPFILE  Temporary decoded file exists

  Encoding types
      UU_ENCODED    UUencoded data
      B64_ENCODED   Mime-Base64 data
      XX_ENCODED    XXencoded data
      BH_ENCODED    Binhex encoded
      PT_ENCODED    Plain-Text encoded (MIME)
      QP_ENCODED    Quoted-Printable (MIME)
      YENC_ENCODED  yEnc encoded (non-MIME)

EXPORTED FUNCTIONS
  Initializing and cleanup
    Initialize is automatically called when the module is loaded and
    allocates quite a small amount of memory for todays machines ;) CleanUp
    releases that again.

    On my machine, a fairly complete decode with DBI backend needs about
    10MB RSS to decode 20000 files.

    CleanUp
        Release memory, file items and clean up files. Should be called
        after a decoidng run, if you want to start a new one.

  Setting and querying options
    $option = GetOption OPT_xxx
    SetOption OPT_xxx, opt-value

    See the "OPT_xxx" constants above to see which options exist.

  Setting various callbacks
    SetMsgCallback [callback-function]
    SetBusyCallback [callback-function]
    SetFileCallback [callback-function]
    SetFNameFilter [callback-function]

  Call the currently selected FNameFilter
    $file = FNameFilter $file

  Loading sourcefiles, optionally fuzzy merge and start decoding
    ($retval, $count) = LoadFile $fname, [$id, [$delflag, [$partno]]]
        Load the given file and scan it for encoded contents. Optionally tag
        it with the given id, and if $delflag is true, delete the file after
        it is no longer necessary. If you are certain of the part number,
        you can specify it as the last argument.

        A better (usually faster) way of doing this is using the
        "SetFNameFilter" functionality.

    $retval = Smerge $pass
        If you are desperate, try to call "Smerge" with increasing $pass
        values, beginning at 0, to try to merge parts that usually would not
        have been merged.

        Most probably this will result in garbled files, so never do this by
        default, except:

        If the "OPT_AUTOCHECK" option has been disabled (by default it is
        enabled) to speed up file loading, then you *have* to call "Smerge
        -1" after loading all files as an additional pre-pass (which is
        normally done by "LoadFile").

    $item = GetFileListItem $item_number
        Return the $item structure for the $item_number'th found file, or
        "undef" of no file with that number exists.

        The first file has number 0, and the series has no holes, so you can
        iterate over all files by starting with zero and incrementing until
        you hit "undef".

        This function has to walk the linear list of fils on each access, so
        if you want to iterate over all items, it is usually faster to use
        "GetFileList".

    @items = GetFileList
        Similar to "GetFileListItem", but returns all files in one go, which
        is very much faster for large number of items, and has no drawbacks
        when used for a small number of items.

  Decoding files
    $retval = $item->rename ($newname)
        Change the ondisk filename where the decoded file will be saved.

    $retval = $item->decode_temp
        Decode the file into a temporary location, use "$item->infile" to
        retrieve the temporary filename.

    $retval = $item->remove_temp
        Remove the temporarily decoded file again.

    $retval = $item->decode ([$target_path])
        Decode the file to its destination, or the given target path.

    $retval = $item->info (callback-function)

  Querying (and setting) item attributes
    $state = $item->state
    $mode = $item->mode ([newmode])
    $uudet = $item->uudet
    $size = $item->size
    $filename = $item->filename ([newfilename})
    $subfname = $item->subfname
    $mimeid = $item->mimeid
    $mimetype = $item->mimetype
    $binfile = $item->binfile

  Information about source parts
    $parts = $item->parts
        Return information about all parts (source files) used to decode the
        file as a list of hashrefs with the following structure:

         {
           partno   => <integer describing the part number, starting with 1>,
           # the following member sonly exist when they contain useful information
           sfname   => <local pathname of the file where this part is from>,
           filename => <the ondisk filename of the decoded file>,
           subfname => <used to cluster postings, possibly the posting filename>,
           subject  => <the subject of the posting/mail>,
           origin   => <the possible source (From) address>,
           mimetype => <the possible mimetype of the decoded file>,
           mimeid   => <the id part of the Content-Type>,
         }

        Usually you are interested mostly the "sfname" and possibly the
        "partno" and "filename" members.

  Functions below are not documented and not very well tested - feedback welcome
      QuickDecode
      EncodeMulti
      EncodePartial
      EncodeToStream
      EncodeToFile
      E_PrepSingle
      E_PrepPartial

  EXTENSION FUNCTIONS
    Functions found in this module but not documented in the uulib
    documentation:

    $msg = straction ACT_xxx
        Return a human readable string representing the given action code.

    $msg = strerror RET_xxx
        Return a human readable string representing the given error code.

    $str = strencoding xxx_ENCODED
        Return the name of the encoding type as a string.

    $str = strmsglevel MSG_xxx
        Returns the message level as a string.

    SetFileNameCallback $cb
        Sets (or queries) the FileNameCallback, which is called whenever the
        decoding library can't find a filename and wants to extract a
        filename from the subject line of a posting. The callback will be
        called with two arguments, the subject line and the current
        candidate for the filename. The latter argument can be "undef",
        which means that no filename could be found (and likely no one
        exists, so it is safe to also return "undef" in this case). If it
        doesn't return anything (not even "undef"!), then nothing happens,
        so this is a no-op callback:

           sub cb {
              return ();
           }

        If it returns "undef", then this indicates that no filename could be
        found. In all other cases, the return value is taken to be the
        filename.

        This is a slightly more useful callback:

          sub cb {
             return unless $_[1]; # skip "Re:"-plies et al.
             my ($subject, $filename) = @_;
             # if we find some *.rar, take it
             return $1 if $subject =~ /(\w+\.rar)/;
             # otherwise just pass what we have
             return ();
          }

LARGE EXAMPLE DECODER
    The general workflow for decoding is like this:

    1. Configure options with "SetOption" or "SetXXXCallback".
    2. Load all source files with "LoadFile".
    3. Optionally "Smerge".
    4. Iterate over all "GetFileList" items (i.e. result files).
    5. "CleanUp" to delete files and free items.

    What follows is the file "example-decoder" from the distribution that
    illustrates the above worklfow in a non-trivial example.

       #!/usr/bin/perl

       # decode all the files in the directory uusrc/ and copy
       # the resulting files to uudst/

       use Convert::UUlib ':all';

       sub namefilter {
          my ($path) = @_;

          $path=~s/^.*[\/\\]//;

          $path
       }

       sub busycb {
          my ($action, $curfile, $partno, $numparts, $percent, $fsize) = @_;
          $_[0]=straction($action);
          print "busy_callback(", (join ",",@_), ")\n";
          0
       }

       SetOption OPT_RBUF, 128*1024;
       SetOption OPT_WBUF, 1024*1024;
       SetOption OPT_IGNMODE, 1;
       SetOption OPT_IGNMODE, 1;
       SetOption OPT_VERBOSE, 1;
       SetOption OPT_AUTOCHK, 0;

       # show the three ways you can set callback functions. I normally
       # prefer the one with the sub inplace.
       SetFNameFilter \&namefilter;

       SetBusyCallback "busycb", 333;

       SetMsgCallback sub {
          my ($msg, $level) = @_;
          print uc strmsglevel $_[1], ": $msg\n";
       };

       # the following non-trivial FileNameCallback takes care
       # of some subject lines not detected properly by uulib:
       SetFileNameCallback sub {
          return unless $_[1]; # skip "Re:"-plies et al.
          local $_ = $_[0];

          # the following rules are rather effective on some newsgroups,
          # like alt.binaries.games.anime, where non-mime, uuencoded data
          # is very common

          # if we find some *.rar, take it as the filename
          return $1 if /(\S{3,}\.(?:[rstuvwxyz]\d\d|rar))\s/i;

          # one common subject format
          return $1 if /- "(.{2,}?\..+?)" (?:yenc )?\(\d+\/\d+\)/i;

          # - filename.par (04/55)
          return $1 if /- "?(\S{3,}\.\S+?)"? (?:yenc )?\(\d+\/\d+\)/i;

          # - (xxx) No. 1 sayuri81.jpg 756565 bytes
          # - (20 files) No.17 Roseanne.jpg [2/2]
          return $1 if /No\.[ 0-9]+ (\S+\....) (?:\d+ bytes )?\[/;

          # try to detect some common forms of filenames
          return $1 if /([a-z0-9_\-+.]{3,}\.[a-z]{3,4}(?:.\d+))/i;

          # otherwise just pass what we have
          ()
       };

       # now read all files in the directory uusrc/*
       for (<uusrc/*>) {
          my ($retval, $count) = LoadFile ($_, $_, 1);
          print "file($_), status(", strerror $retval, ") parts($count)\n";
       }

       Smerge -1;

       SetOption OPT_SAVEPATH, "uudst/";

       # now wade through all files and their source parts
       for my $uu (GetFileList) {
          print "file ", $uu->filename, "\n";
          print " state ", $uu->state, "\n";
          print " mode ", $uu->mode, "\n";
          print " uudet ", strencoding $uu->uudet, "\n";
          print " size ", $uu->size, "\n";
          print " subfname ", $uu->subfname, "\n";
          print " mimeid ", $uu->mimeid, "\n";
          print " mimetype ", $uu->mimetype, "\n";

          # print additional info about all parts
          print " parts";
          for ($uu->parts) {
             for my $k (sort keys %$_) {
                print " $k=$_->{$k}";
             }
             print "\n";
          }

          $uu->remove_temp;

          if (my $err = $uu->decode) {
             print " ERROR ", strerror $err, "\n";
          } else {
             print " successfully saved as uudst/", $uu->filename, "\n";
          }
       }

       print "cleanup...\n";

       CleanUp;

PERLMULTICORE SUPPORT
    This module supports the perlmulticore standard (see
    <http://perlmulticore.schmorp.de/> for more info) for the following
    functions - generally these are functions accessing the disk and/or
    using considerable CPU time:

       LoadFile
       $item->decode
       $item->decode_temp
       $item->remove_temp
       $item->info

    The perl interpreter will be reacquired/released on every callback
    invocation, so for performance reasons, callbacks should be avoided if
    that is costly.

    Future versions might enable multicore support for more functions.

BUGS AND LIMITATIONS
    The original uulib library this module uses was written at a time where
    main memory of measured in megabytes and buffer overflows as a security
    thign didn't exist. While a lot of security fixes have been applied over
    the years (includign some defense in depth mechanism that can shield
    against a lot of as-of-yet undetected bugs), using this library for
    security purposes requires care.

    Likewise, file sizes when the uulib library was written were tiny
    compared to today, so do not expect this library to handle files larger
    than 2GB.

    Lastly, this module uses a very "C-like" interface, which means it
    doesn't protect you from invalid points as you might expect from "more
    perlish" modules - for example, accessing a file item object after
    callinbg "CleanUp" will likely result in crashes, memory corruption, or
    worse.

AUTHOR
    Marc Lehmann <schmorp@schmorp.de>, the original uulib library was
    written by Frank Pilhofer <fp@informatik.uni-frankfurt.de>, and later
    heavily bugfixed by Marc Lehmann.

SEE ALSO
    perl(1), uudeview homepage at <http://www.fpx.de/fp/Software/UUDeview/>.

