vms_zip.rnh

给出了 zip 压缩算法的完整实现过程。

.sk
Under VMS, -d is case sensitive when it matches names in the zip file.
This allows deleting names that were zipped on other systems, but requires
that the names be entered in upper case if they were zipped on an MSDOS
system (by PKZIP or in PKZIP compatibility mode), so that the names can be
found in the zip file and deleted.
.!------------------------------------------------------------------------------
.indent -4
2 More_Options
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As mentioned before, Zip will use the best of two methods: deflate or store.
The option -0 will force Zip to use store on all files. For example:
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zip -r0 foo foo.dir
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will zip up the directory foo into foo.zip using only store.
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The speed of deflation can also be controlled with options -1 (fastest
method but less compression) to -9 (best compression but slower). The
default value is -6. For example:
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zip -r8 foo foo.dir
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In nearly all cases, a file that is already compressed cannot be compressed
further by Zip, or if it can, the effect is minimal.  The -n option
prevents Zip from trying to compress files that have the
given suffixes.  Such files are simply stored (0%
compression) in the
output zip file, so that Zip doesn't waste its time trying to compress
them. The suffixes are separated by
either colons or semicolons.  For example, in DCL:
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.indent 10;$ zip -rn ".Z:.zip:.tiff:.gif:.snd" foo [.FOO]*.*
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will put everything in [.FOO] into FOO.ZIP, but will store any files that end
in .Z, .ZIP, .TIFF, .GIF, or .SND without trying to compress them.  (Image and
sound files often have their own specialized compression methods.)
The default suffix list is ".Z:.zip;.zoo:.arc:.lzh:.arj".
The environment variable ZIPOPT can be used to change this default. For
example:
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.indent 10;$ ZIPOPT == "-n .Z:.zip:.tiff:.gif:.snd"
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The variable ZIPOPT can be used for any option (except -i and -x)
and can include several options.
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For VMS Zip, the alternatively environment variable name ZIP_OPTS may
be used, if a more "VMS-like" name is prefered. If both ZIPOPT and
ZIP_OPTS are present (and do not equate to whitespace only),
the content of ZIPOPT takes precedence and ZIP_OPTS is ignored.
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Under Unix, Zip will store the full path (relative to the current path)
and name of the file (or just the name if -j is specified) in the zip
file along with the Unix attributes, and it will mark the entry as made
under Unix.  If the zip file is intended for PKUNZIP under MSDOS, then
the -k (Katz) option should be used to attempt to convert the names and
paths to conform to MSDOS, store only the MSDOS attribute (just the
user write attribute from Unix), and mark the entry as made under MSDOS
(even though it wasn't).
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The -o (older) option will set the "last modified" time of the zip file to
the latest "last modified" time of the entries in the zip file.  This can
be used without any other operations, if desired.  For example:
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$ zip -o foo
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will change the last modified time of FOO.ZIP to the latest time of the
entries in FOO.ZIP.
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The -e and -c options operate on all files updated or added to the zip
file.  Encryption (-e) will prompt for a password on the terminal and will
not echo the password as it is typed (if SYS$COMMAND is not a TTY, Zip will
exit with an error). New zip entries will be encrypted using that password.
For added peace of mind, Zip will prompt for the password a second time,
checking that the two inputs are the same before using it.
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One-line comments can be added for each file with the -c option.  The zip
file operations (adding or updating) will be done first, and you will then
be prompted for a one-line comment for each file.  You can then enter the
comment followed by return, or just return for no comment.
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The -z option will prompt you for a multi-line comment for the entire zip
file.  This option can be used by itself, or in combination with other
options.  The comment is ended by a line containing just a period, or an
end of file condition (^D on Unix, ^Z on MSDOS, OS/2, and OpenVMS).
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The -q (quiet) option eliminates the informational messages and comment
prompts while Zip is operating.  This might be used in shell scripts, for
example, or if the zip operation is being performed as a background task
("$ spawn/nowait zip -q foo *.c").
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Zip can take a list of file names to operate on from SYS$INPUT using the
"-@"
option.
.!  In Unix, this option can be used with the find command to extend
.!greatly the functionality of Zip. For example, to zip up all the C source
.!files in the current directory and its subdirectories, you can:
.!.sk
.!find . -type f -name "*.[ch]" -print | zip source -@
.!.sk
.!Note that the pattern must be quoted to keep the shell from expanding it.
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The -X option (remember to quote it!) suppresses saving of additional
"extra file attributes" in the zipfile. Its effect is to disable the
VMS only -V option (see below), and prevent storing of UNIX compatible
GMT modification time stamps. These UNIX compatible GMT time stamps
-- which are quite useful when transporting Zip archives world wide (but
are only recognized by Info-ZIP's UnZip 5.20 or later) --
are included in the zipfile unless -X or -V is specified (in case your
version of Zip has the USE_EF_UT_TIME option compiled in).
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Under VMS only, the -w option will append the version number of the files
to the name and zip up multiple versions of files.  Without -w, Zip will
only use the most recent version of the specified file(s).
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One more option that valid only under VMS is -V option. This option saves
all (hopefully) file attributes needed to make EXACT copy of the
file after extraction from archive. To extract a file with saved attributes,
use UnZip version 5.20 or later. Note that to specify this option you should
quote it ("-V"). Be carefull: it's rather hard (if possible at all) to extract
a file archived on VMS with this option specified on other systems. See
documentation on UnZip for further information.
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The -l option translates the Unix end-of-line character LF into the
MSDOS convention CR LF. This option should not be used on binary files.
This option can be used on Unix or VMS if the zip file is intended for
PKUNZIP under MSDOS.
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If Zip is run with the -h option, or with no arguments and standard output is
a terminal, the license and the command-argument and option help is shown.
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The -L option shows the Zip license.
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The -v option, when given as the only command line argument, directs Zip to
display diagnostic information that shows when and how the executable was
built and set up. This includes info on used compiler and compiler version
(if available) as well as any optional compile time feature flags.
Additionally, the content of the environment variables
(logical names) read by Zip for runtime configuration are shown. This
information is especially valuable when reporting problems or bugs.
.!------------------------------------------------------------------------------
.indent -4
2 Diagnostics
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       On VMS, Zip's UNIX style exit values are mapped into proper
       VMS status codes:
.literal
   1                                  (success)  normal exit,
   (0x7fff0000 + 16*Zip_error_level)  warnings
   (0x7fff0002 + 16*Zip_error_level)  normal errors
   (0x7fff0004 + 16*Zip_error_level)  fatal errors
.end literal

       The Zip error level (or exit code) approximates the exit
       codes defined by PKWARE and takes on the following values:
.literal

  VMS        Zip      Type of error
  severity   errcode
    -          0      normal; no errors or warnings detected.
    F          2      unexpected end of zip file.
    E          3      a generic error in the  zipfile  format  was
                      detected.   Processing  may  have  completed
                      successfully anyway;  some  broken  zipfiles
                      created by other archivers have simple work-
                      arounds.
    F          4      zip was unable to allocate memory for one or
                      more  buffers during program initialization.
    F          5      a severe error in  the  zipfile  format  was
                      detected.   Processing probably failed imme-
                      diately.
    E          6      entry too large to be split with zipsplit
    E          7      invalid comment format
    F          8      zip -T failed or out of memory
    E          9      the user aborted zip prematurely  with  con-
                      trol-C (or similar)
    F          10     zip  encountered an error while using a temp
                      file
    F          11     read or seek error
    W          12     zip has nothing to do
    E          13     missing or empty zip file
    F          14     error writing to a file
    F          15     zip was unable to create a file to write to
    E          16     bad command line parameters
    E          18     zip could not open a specified file to read
.end literal
.!------------------------------------------------------------------------------
.indent -4
2 Copyright
.br
     Copyright (C) 1990-1997 Mark Adler, Richard B. Wales, Jean-loup Gailly,
     Onno van der Linden, Christian Spieler and Igor Mandrichenko.
     Permission is granted to any individual or institution to use, copy, or
     redistribute this software so long as all of the original files are
     included, that it is not sold for profit, and that this copyright
     notice is retained.
.sk
     LIKE ANYTHING ELSE THAT'S FREE, ZIP AND ITS ASSOCIATED UTILITIES
     ARE PROVIDED AS IS AND COME WITH NO WARRANTY OF ANY KIND, EITHER
     EXPRESSED OR IMPLIED. IN NO EVENT WILL THE COPYRIGHT HOLDERS BE
     LIABLE FOR ANY DAMAGES RESULTING FROM THE USE OF THIS SOFTWARE.
.sk
     Please send bug reports or comments by email to:
     [e-mail].  For bug reports, please include
     the version of Zip (see zip -h), the make options you used to
     compile it (see zip -v), the machine and operating system you are using,
     and as much additional information as possible.
     Thank you for your support.
.!------------------------------------------------------------------------------
.indent -4
2 Acknowledgements
.br
     Thanks to R. P. Byrne  for  his  Shrink.Pas  program,  which
     inspired  this  project, and from which the shrink algorithm
     was stolen; to Phil Katz for placing in  the  public  domain
     the  zip  file format, compression format, and .ZIP filename
     extension, and for accepting minor changes to the file  for-
     mat; to Steve Burg for clarifications on the deflate format;
     to Keith Petersen, Rich Wales, Hunter Goatley and Mark Adler
     for  providing  a mailing list and ftp site for the Info-ZIP
     group to use; and most importantly, to  the  Info-ZIP  group
     itself  (listed in the file infozip.who) without whose tire-
     less testing and bug-fixing efforts a portable zip would not
     have  been  possible.   Finally  we should thank (blame) the
     first Info-ZIP moderator, David Kirschbaum, for  getting  us
     into  this  mess  in  the  first place.
.!------------------------------------------------------------------------------
.indent -4
2 Bugs
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     Zip 2.2 is not compatible with PKUNZIP 1.10. Use Zip 1.1 instead
     to produce zip archives which can be extracted by PKUNZIP 1.10.
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     WARNING: zip files produced by this version of zip must not be
     *updated* by zip 1.0 or PKZIP 1.10 or PKZIP 1.93a, if they contain
     encrypted members, or if they have been produced in a pipe or on a non
     seekable device. The old versions of zip or pkzip would destroy the
     zip structure. The old versions can list the contents of the zip file
     but cannot extract it anyway (because of the new compression algorithm).
     If you do not use encryption and use regular disk files, you do
     not have to care about this problem.
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     Under VMS, not all of the odd file formats are treated properly.
     Only zip files of format stream-LF and fixed length 512 byte are
     expected to work with Zip.  Others can be converted using Rahul
     Dhesi's BILF program.  This version of Zip handles some of the
     conversion internally.  The use of the "-V" option to save the
     VMS attributes should work without problem for at least all types
     of sequential files.  Beginning with Zip 2.2, the "-V" option uses
     a new format to store the VMS attributes that should now allow
     proper restoration of all sorts of indexed files. It has been
     approved that there are problems with VMS UnZip to restore some
     indexed files which were saved with previous versions of Zip.
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     When using Kermit to transfer zip files from VMS to MSDOS, type "set
     file type block" on the VMS side.  When transfering from MSDOS to VMS,
     type "set file type fixed" on the VMS machine.  In both cases, type
     "set file type binary" on MSDOS.
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     Under VMS, zip hangs for file specification that uses DECnet
     syntax (foo::*.*).
.sk
     LIKE ANYTHING ELSE THAT'S FREE, ZIP AND ITS ASSOCIATED UTILITIES
     ARE PROVIDED AS IS AND COME WITH NO WARRANTY OF ANY KIND, EITHER
     EXPRESSED OR IMPLIED. IN NO EVENT WILL THE COPYRIGHT HOLDERS BE
     LIABLE FOR ANY DAMAGES RESULTING FROM THE USE OF THIS SOFTWARE.
.sk
     That having been said, please send any problems or comments
     via email to the Internet address [e-mail].  For
     bug reports, please include the version of Zip, the make
     options you used to compile it, the machine and operating
     system you are using, and as much additional information as
     possible.  Thank you for your support.
.!------------------------------------------------------------------------------