readme.cms

给出了 zip 压缩算法的完整实现过程。

Using ZIP and UNZIP on VM/CMS
=============================


Installing executables
----------------------

The following CMS MODULEs are available:
   ZIP
   ZIPNOTE
   ZIPCLOAK
   ZIPSPLIT
   UNZIP

In addition to these, each MODULE file also has an EXEC with the same
name.  These EXECs are front-ends to the MODULES that will attempt to
set up the required runtime libraries before running the MODULE.
All the EXECs are identical.  Only their names are different.
They are stored as plain text files.

The CMS MODULE files have been packed using the COPYFILE command to
allow their file format to be properly restored, since variable length
binary files will not currently unzip properly (see below for details).
The MODULEs are shipped with a filetype or extension of CMO (for CMS
MODULE).  Their names may vary on the distribution disk to indicate
their level, etc.

To restore them to executable MODULEs on CMS, do the following:
   1. Upload them to CMS with a Fixed record length with LRECL 1024.
      Example, from a DOS or OS/2 window, type this:
         SEND unzip.cmo A:unzip module a (RECFM F LRECL 1024

      Example, using FTP from CMS, type this:
         BINARY FIXED 1024
         GET unzip.cmo unzip.module.a

      Note:  Replace "unzip.cmo" with the actual name.

   2. Use COPYFILE to unpack the file.
      Example, in CMS type this:
         COPYFILE UNZIP MODULE A (UNPACK REPLACE OLDDATE

   3. Repeat steps 1-2 for each of the programs.

   4. Build the ZIPINFO module by typing this:
         COPYFILE UNZIP MODULE A ZIPINFO MODULE A (OLDDATE

   5. Upload the EXECs to CMS as text files (with ASCII-to-EBCDIC
      translation).
      Example, from a DOS or OS/2 window, type this:
         SEND unzip.exc A:unzip exec a (CRLF

      Example, using FTP from CMS, type this:
         GET unzip.exc unzip.exec.a

   6. Repeat steps 4 for each of the EXECs.


Preparing the environment
-------------------------

The executables provided were compiled with IBM C 3.1.0 and
require the the Language Environment (LE) runtime libraries.

To provide access to the runtime libraries:
   1. Link to the disk containing the Language Environment files,
      if necessary.

   2. Use the command "GLOBAL LOADLIB SCEERUN"

   These commands can be placed in your PROFILE EXEC.

   Note:  EXECs have been provided called ZIP, UNZIP, etc. that
   issue the GLOBAL LOADLIB statement.  This was done to alleviate
   frustration of users that don't have the GLOBAL LOADLIB statement
   in their PROFILE EXEC.  These EXECs may require changing for
   your system.

   Unfortunately, there is no way, using IBM C, to produce a MODULE
   that doesn't require a runtime library.


Testing
-------

To test the MODULEs, just type ZIP or UNZIP.  They should
show help information on using the commands.

If you see something like this:
   DMSLIO201W The following names are undefined:
    CEEEV003
   DMSABE155T User abend 4093 called from 00DCD298 reason code 000003EB

Then you don't have access to the proper runtime libraries, as
described above.

Here is additional information on the ZIP and UNZIP programs that
may assist support personnel:
   - Compiled with IBM C V3R1M0 on VM/ESA 2.2.0 with
     CMS level 13 Service Level 702.

   - Require the SCEERUN LOADLIB runtime library.  This is
     part of the Language Environment (LE).

   - Linked with options RMODE ANY AMODE ANY RLDSAVE.

If you continue to have trouble, report the problem to Zip-Bugs
(see the bottom of this document).



Compiling the source on VM/CMS
------------------------------

The source has been successfully compiled previously using
C/370 2.1 and 2.2.  The source has been recently compiled using
IBM C 3.1.0 on VM/ESA 2.2.0 with CMS level 13.  I don't have
access to an MVS system so the code hasn't been tested there
in a while.

 1. Unzip the source files required for CMS.  The root-level files
    inside the ZIP file and the files in the CMSMVS subdirectory are
    needed.  Example (use both commands):
       unzip -aj zip23.zip -x */*   -dc
       unzip -aj zip23.zip cmsmvs/* -dc

    This example unzips the files to the C-disk, while translating
    character data and ignoring paths.

    If you don't already have a working UNZIP MODULE on CMS you will
    have to unzip the files on another system and transport them
    to CMS.  All the required files are plain text so they can
    be transferred with ASCII-to-EBCDIC translations.

 2. Repeat step 1 with the zip file containing the UNZIP code.
    Unzip the files to a different disk than the disk used for the ZIP
    code.

 3. To compile the ZIP code, run the supplied CCZIP EXEC.
    To compile the UNZIP code, run the supplied CCUNZIP EXEC.

NOTE:
Some of the ZIP and UNZIP source files have the same name.  It is
recommended that you keep the source from each on separate disks and
move the disk you are building from ahead of the other in the search
order.

For example, you may have a 192 disk with the ZIP source code and
a 193 disk with the UNZIP source code.  To compile ZIP, access
the 192 disk as B, then run CCZIP.  This will create the following
modules:  ZIP, ZIPNOTE, ZIPSPLIT, ZIPCLOAK.

To compile UNZIP, access 193 as B, then run CCUNZIP.  This will create
the following modules:  UNZIP, ZIPINFO (a copy of UNZIP).


=========================================================================


Using ZIP/UNZIP
---------------

Documentation for the commands is in MANUAL NONAME (for ZIP) and in
UNZIP DOC UNZIP.  INFOZIP DOC describes the use of the -Z option of
UNZIP.

The rest of this section explains special notes concerning the VM/CMS
version of ZIP and UNZIP.


Filenames and directories
-------------------------

 1. Specifying filenames

    a. When specifying CMS files, use filename.filetype.filemode format
       (separate the three parts of the name with a period and use no
       spaces).  Example:  profile.exec.a

       Unfortunately, this prevents you from using ZIP from
       FILELIST.  To unzip a zip file, however, you can type something
       like this next to it in FILELIST:
          unzip /n -d c

       This will unzip the contents of the current file to a C-disk.

    b. It is possible to use DD names with ZIP and UNZIP on CMS, though
       it can be cumbersome.  Example:
          filedef out disk myzip zip a
          zip dd:out file1.txt file2.txt

       While you can also use a DD name for the input files, ZIP
       currently does not correctly resolve the filename and will
       store something like "dd:in" inside the ZIP file.  A file stored
       in this manor cannot easily be unzipped, as "dd:in" is an invalid
       filename.

    c. In places where a directory name would be used on a PC, such as
       for the ZIP -b (work path) option or the UNZIP -d (destination
       path) options, use a filemode letter for CMS.  For example,
       to unzip files onto a C-disk, you might type something like this:
          unzip myzip.zip -d c

       Currently, ZIP uses the A-disk for work files.  When zipping
       large files, you may want to specify a larger disk for work files.
       This example will use a C-disk for work files.
          zip -b C myzip.zip.c test.dat.a


 2. Filename conversions

    a. Filemode letters are never stored into the zip file or take from
       a zip file.  Only the filename and filetype are used.
       ZIP removes the filemode when storing the filename into the
       zip file.  UNZIP assumes "A" for the filemode unless the -d
       option is used.

    b. When unzipping, any path names are removed from the fileid