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439 lines
23 KiB
439 lines
23 KiB
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UNARCU
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Universal Archive File Extraction Utility
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Version 1.1
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CP/M 2.2 Bug fix by Lars Nelson
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February 4, 2025
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Modified for Universal use by Lars Nelson
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September 17, 2023
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Modified for ZCPR3 by Gene Pizzetta
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December 9, 1990
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Original CP/M 2.2 version is
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Copyright (C) 1986, 1987 by Robert A. Freed
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All Rights Reserved
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UNARCU allows the listing, typeout, printing, checking, and extraction of
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member files contained in ARK and ARC archive files. These are commonly
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used for compressed file storage on remote access bulletin boards. This is
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a universal version and runs on the following CP/M compatible systems:
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CP/M 2.2 with DRI CCP or ZCPRD&J
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ZSDOS 1.2 and 2.0 with DRI CCP, ZCPRD&J or Zsystem
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CP/M 3 with DRI CCP or Z3Plus
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ZPM3 with DRI CCP or ZCCP
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DU file specification is supported on all systems. If Zsystem is active
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then named directories can be used and the bad directories flag is
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automatically checked.
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If datestamping is available then extracted files will recieve the ARK file's
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stored date stamp. The program handles DateStamper, NZTIME and CP.M Plus
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date stamping methods.
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UNARCU requires at least 32K of free memory (TPA) for full support of all
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archive file formats, but smaller systems may be able to use some of the
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program's capabilities.
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USAGE:
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UNARCU {DU: or dir:}arcfile{.typ} {DU: or dir:}{afn.aft} {{/}options}
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If a DIR or DU specification is not given for the archive file, the current
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drive/user is assumed. The second filename, which can be ambiguous,
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refers to a member file or files in the archive. DIR: file specification
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only available when Zsystem is active. DU: specification always available.
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If a DU or DIR specification is provided for the member filespec, it will be
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extracted to that directory. To extract to the current directory, only a
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colon is required. If a directory specification is given without a filename,
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all files ("*.*") is assumed.
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If no DU or DIR specification is given, UNARCU acts differently depending
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on whether the member name is ambiguous or not. If the member name is
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unambiguous, and the filetype is not restricted, the file will be typed to
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the screen. If the member name is ambiguous, or if no member name is
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given at all, a directory of the ARK will be displayed.
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If no filetype is given for the archive file, UNARCU first tries ARK and then
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ARC.
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An on-line help message will be displayed if UNARCU is called with no
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command tail or if the command tail is "//".
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OPTIONS: Options may or may not be preceded by a slash, but the slash is
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required if the options are not the third token (element) on the command
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line.
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C Check the validity of the archive and the given member
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files. If a member filespec is not given, all files
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("*.*") is assumed.
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E Toggle erasing of existing files without asking on and
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off. UNARCU may be configured to automatically erase,
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during member file extraction, existing files in the
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target directory that have the same name. Or it can
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be configured to ask first. This option will turn off
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user query before erasure, if it is on by default, and
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vice versa.
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N Toggle console paging on or off. UNARCU may be
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configured to default to console paging or not. This
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option will turn paging off, if the the default is on,
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and vice-versa. Paging effects both archive directory
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display and member file type-out. During member file
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extraction, console paging is always off.
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P Sends a member file to the printer (LST device). The
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member name cannot be ambiguous. The file will be
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printed continuously, with no formatting or paging.
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UNARCU can be aborted at any time with ^C or ^K.
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If screen paging is enabled, UNARCU pauses after the screen fills. The
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listing may be resumed by typing any key other than ^S, ^C, or ^K. The
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space bar displays one more line of output (overwriting the "[more]"
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message) and the program will again pause. For hard copy terminals, line
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feed may be used to prevent overprinting of the "[more]" line. If paging
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is disabled, the display can be paused with ^S.
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LISTING AN ARCHIVE DIRECTORY: UNARC always produces a detailed
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console listing of all the member files of an archive, or of those members
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which match the second file specification, if one is given. If no member
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name is given, or if the member name is ambiguous, then UNARCU only lists
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the directory, without doing anything else. (That is, unless the C option is
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included.)
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A sample directory listing:
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A0>UNARCU CODES
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Archive File = A0:CODES.ARK
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Name Length Disk Method Ver Stored Saved Date Time CRC
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============ ======= ==== ======== === ======= ===== ========= ====== ====
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ABLE .DOC 24320 24k Crunched 8 11777 52% 30 Apr 86 10:50a 42C0
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BRAVO .COM 17152 17k Squeezed 4 14750 14% 2 May 86 4:11p 8CBD
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CHARLIE .TXT 234 1k Packed 3 99 58% 2 May 86 4:11p 8927
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==== ======= ==== ======= === ====
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Total 3 41706 42k 26626 36% 58A4
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The listing is equivalent to the "verbose" listing of the MS-DOS ARC
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program, with the addition of the "Disk" and "Ver" fields, which are unique
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to UNARCU and previous UNARC versions. The listing requires 78-columns
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of terminal width.
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"Name" is the filename which will be generated if the file is extracted by
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UNARCU. This is not necessarily the same as the name recorded in the
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archive file. Although CP/M and MS-DOS file naming conventions are
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identical, two conversions are made to guarantee filename validity: Lower-
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case letters are converted to upper-case and non-printing characters are
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converted to dollar signs ("$"). Archive entries are usually maintained and
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listed in alphabetical order.
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"Length" is the uncompressed file length, i.e., the number of bytes the file
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will occupy if extracted to disk, exclusive of any additional length imposed
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by the file system. MS-DOS permits files of arbitrary lengths, but CP/M
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restricts files to multiples of 128 bytes.
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"Disk" is the actual amount of space required to extract the file to a CP/M
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disk, expressed as a multiple of 1K (1024) bytes. The number is dependent
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on the output drive's allocation block size, which can range from 1K to 16K
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bytes. Typically, 1K is used for single-density floppy disks, 2K for
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double-density floppies, and 4K for hard disks. In the absence of an
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explicit output drive, UNARCU uses the block size of the currently logged
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drive, or a configured default size.
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"Method" is the compression method used: "Unpacked", "Packed",
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"Squeezed", "Crunched", "Squashed", or "Unknown!". If the method
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"Unknown!" appears, it likely indicates a faulty archive file or a newer
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compression method not yet supported by UNARCU.
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"Ver" is the version of compression method used. UNARC supports versions
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1-9: unpacked files, versions 1 or 2; packed files, version 3; squeezed
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files, version 4; crunched files, versions 5 and squashed files, version 9.
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"Stored" is the compressed file length, that is, the number of bytes
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occupied by the file in the archive, not including the directory information
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overhead, which adds an additional 29 bytes to each member file.
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"Saved" indicates the percentage of the original file length which was saved
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by compression. Higher values indicate better compression. The MS-DOS
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ARC documentation refers to this as the "stowage factor". The value shown
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in the totals applies to the archive as a whole, excluding directory
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overhead.
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"Date" and "Time" are the file modification stamp at the time it was added
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to the archive.
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"CRC" is an internal 16-bit cyclic redundancy check value computed when a
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file is added to an archive, expressed in hexadecimal. UNARCU checks file
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validity by recomputing this value when it extracts a file. The value is
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calculated by a different method than that used by either of the two
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popular public domain programs, CRCK and CHEK, but it is a quite valid and
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reliable error-detection mechanism. The value is given for completeness
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only. The total in the last line is the 16-bit sum of the displayed CRC
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values and is useful for comparing entire archives. Since the CRC values
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are computed before compression, the total should be the same for all
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archives created from the same set of input files, without regard for
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variations in file order or compression methods.
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The "Total" line is displayed only if more than one file appears in the
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listing.
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EXTRACTING FILES FROM AN ARCHIVE: If the second command line
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parameter contains a DU or DIR specification UNARCU will extract the
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selected member file or files to to the indicated disk directory. If the
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directory specification is given without a filename, all member files will be
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extracted to the indicated directory. If only a colon is given, the current
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drive/user will be assumed.
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Below is a directory listing as might be generated during file extraction,
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along with some possible warning messages:
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A0>UNARCU CODES B1:
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Archive File = A0:CODES.ARK
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Output Directory = B1:
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Name Length Disk Method Ver Stored Saved Date Time CRC
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============ ======= ==== ======== === ======= ===== ========= ====== ====
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ABLE .DOC 24320 24k Crunched 8 11777 52% 30 Apr 86 10:50a 42C0
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Replace existing output file (y/n)? Y
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BRAVO .COM 17152 18k Squeezed 4 14740 14% 2 May 86 4:11p 8CBD
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Warning: Extracted file has incorrect CRC
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Warning: Extracted file has incorrect length
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Warning: Bad archive file header, bytes skipped = 10
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CHARLIE .TXT 234 2k Packed 3 99 58% 2 May 86 4:11p 8927
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==== ======= ==== ======= === ====
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Total 3 41706 44k 26616 36% 58A4
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"Replace existing output file (y/n)?" appears if a file of the same name
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exists in the output directory, requiring a "Y" or "N" response. Any
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response other than "Y" will be consided to be the same as "N". If UNARCU
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has been configured to erase without query, this message will not appear.
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The first two of the "Warning:" messages above indicate that either the
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cyclic redundancy check (CRC) value or the extracted file length does not
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match the value recorded in the archive header when the original file was
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added. The third warning message is displayed if the proper format for
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the beginning of a new member is not detected, but UNARCU recovered by
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skipping a certain number of bytes in the archive file. If a recovery
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attempt fails, UNARC aborts and issues a different message, "Invalid archive
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file format". The appearance of any of these messages probably means the
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file data has been corrupted in some way.
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If the original MS-DOS file length was not an exact multiple of 128 bytes,
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the final record of the extracted file will be padded with 1Ah characters
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(ASCII ^Z).
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Disk space in the listing will be correct for the specified output directory.
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In the two examples above, drive A has 1K allocation blocks while drive B
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has a 2K blocks, which accounts for the differences in the two listings. To
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determine the exact disk space requirements before extracting files, log
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into the desired output drive and take an UNARCU directory listing of the
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ARK file.
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If a file extraction is aborted with ^C, any partial output file will have to
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be deleted manually.
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TYPING MEMBER FILES: Typing the contents of a member file in an archive
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to the console may be requested by giving a non-ambiguous filename and no
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output disk directory as the second command line parameter. For example:
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A0>UNARCU CODES ABLE.DOC
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Archive File = A0:CODES.ARK
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Name Length Disk Method Ver Stored Saved Date Time CRC
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============ ======= ==== ======== === ======= ===== ========= ====== ====
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ABLE .DOC 24320 24k Crunched 8 11777 52% 30 Apr 86 10:50a 42C0
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-------------------------------------------------------------------------------
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This is file ABLE.DOC, contained within the archive CODES.ARK. Typeout will
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proceed until the end of this file, so you'd better be patient. For somebody
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who has nothing to say, I've written an awfully big file here. If you don't
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want to read all 24K of it, you can type ^C ....
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The specified file is assumed to contain valid ASCII text data. All bytes
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are masked to seven bits and all control characters are ignored except
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horizontal tabs, which are expanded to blanks with stops at every eighth
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column), and line feeds, vertical tabs, and form feeds, all of which generate
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a new line. SUB (^Z) is interpreted as the end of the file. Backspaces and
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carriage returns are ignored, so text will not be obscured.
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UNARCU will refuse to type files whose filetype indicates are not ASCII text
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files, including COM, CMD, EXE, OBJ, OVL, REL, PRL, CRL, IRL, INI, SYS,
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BAD, ARK, ARC, LBR, ?Q?, ?Y? and ?Z?. If one of these or other restricted
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types is given, directory information only is listed.
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CRC and file length checking are not performed when a file is typed to the
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screen.
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PRINTING MEMBER FILES: A single member file may be sent to the printer
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(CP/M LST device) with the "P" option as the third parameter on the
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command line with or without a preceding slash. In addition, the member
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name must be non-ambiguous and must not be preceded by a drive or user
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specification. For example:
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A0>UNARCU CODES CHARLIE.TXT P
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or
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A0>UNARCU CODES CHARLIE.TXT /P
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The contents of the specified file is passed directly to the printer without
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alteration, additional formatting, or even paging. The user should make
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sure it contains data suitable for printer output. This unfiltered operation
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is particularly well-suited for the output of binary graphics images to
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dot-matrix printers. These files can be extremely large, but compress quite
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well, often to less than 5% of their original size. The same filetypes
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excluded from typing are also excluded from printing. Printing may be
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paused or aborted with ^S and ^C respectively.
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CHECKING MEMBER FILES: With the "C" option UNARCU can be directed to
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extract one or more member files from an archive, without actually storing
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them as disk files. This operation performs file CRC and length checking,
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so it is useful for verifying correct modem data transmission of an archive.
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If the "C" is the second parameter on the command line, it must be
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preceded by a slash. In that case all files in the archive will be checked.
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If a member filename is given, it may be ambiguous, but it cannot be
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preceded by a disk directory specification. For example:
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A0>UNARCU CODES *.DOC C
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or
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A0>UNARCU CODES /C
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FILE DATE STAMPING: ARK and ARC files contain only a member file's
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modification date and time. When a member is extracted under ZSDOS or
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CP/M 3 with date stamping, its modification date will be transferred to disk
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as both the create and modification file date stamps. If the modification
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date is not included in the archive, then the extracted file will be stamped
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with the current date and time.
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SECURITY: Z-Node security is handled automatically by UNARCU when
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Zsystem is running. If the Wheel byte is off (reset), file extraction,
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archive checking, and file printing are all disabled. In addition, UNARCU
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can be configured to disable file type-out or to limit type-out to a maximum
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number of lines.
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Directory security depends on the file specification parsing of ZCPR 3.3 or
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higher to indicate that the DU or DIR are illegal. Security should be
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adequate, however, under other CPR's.
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PROGRAM CONFIGURATION OPTIONS: Several configuration bytes are
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available to tailor the program for specific requirements, particularly for
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RCP/M systems. With the Wheel byte off, UNARCU can be used by remote
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callers only for archive directory listing and, optionally, for member file
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typeout.
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Configuration bytes also determine the default conditions for the N and E
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command line options and the filetypes excluded from type-out.
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Other configuration points are provided for non-standard systems and need
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not concern the majority of users running ZCPR3, NZ-COM, or Z3PLUS.
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Patching is accomplished using ZCNFG and the configuration file,
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UNARCUnn.CFG, where nn is the current version. The options are discussed
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in detail in the CFG file help screens. ZCNFG will find the CFG file
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automatically, even if you change the name of the program, as long as you
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do not change the name of the CFG file.
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For most users no configuration is necessary.
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ABOUT ARC/ARK FILES: The files which UNARCU processes utilize a format
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that was introduced by the ARC shareware utility program, which executes
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on 16-bit computers running the MS-DOS (or PC-DOS) operating system.
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This format has achieved widespread popularity since the ARC program
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first appeared in March 1985, and it has become the de facto standard for
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file storage on remote access systems catering to 16-bit computer users.
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This file format also achieved popularity on RCP/Ms (Remote CP/M) systems.
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While ARC files have given way to ZIP files in general, many ARC files are
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available on the web containing CP/M software.
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RCP/M system operators adopted the convention of naming CP/M archive
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files with the filetype ARK. This differentiates these from MS-DOS archive
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files, which use the filetype ARC. This is a naming convention only; there
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is no difference in format, and UNARC will accept files of either type
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interchangeably.
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An archive is a group of files compressed and collected together into a
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single file in such a way that the individual files may be recovered intact.
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In this respect, archives are similar in function to libraries (LBR files),
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which have been commonplace on CP/M systems since 1982, when the
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original LU library utility program was introduced by Gary P. Novosielski.
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The two file formats, however, are not compatible.)
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The distinguishing characteristic of an ARC archive is that its component
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files are automatically compressed when they are added to the archive, so
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that the resulting file occupies a minimum amount of disk space. Of
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course, file compression techniques have also been commonplace in the CP/M
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world since 1981, when the public domain SQ and USQ "squeeze and
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unsqueeze" programs were introduced by Richard Greenlaw.
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The SQ/USQ programs and their numerous popular descendants utilize a
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well-known general-purpose form of data compression (Huffman coding).
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This technique, which is also utilized in ARC files, performs well for many
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text files but often produces poor compression of binary files (e.g., object
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program COM files). The ARC program also provides an advanced data
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compression method, which it terms "crunching." This method (which is
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based on the Lempel-Ziv-Welch or "LZW" algorithm) performs better than
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squeezing in most cases, often achieving 50% or better compression of ASCII
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text files, 15-40% compression of binary object files, and as much as 95%
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compression of bit-mapped graphics image files.
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Five different methods are actually employed for storing files in an
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archive. The method chosen for a particular file is the one which results
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in the best compression for that file:
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1. No compression ("unpacked"). The file is stored in its
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original form.
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2. Run-length encoding ("packed"). Repeated sequences of 3-
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255 identical bytes are compressed into a three-byte sequence.
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3. Huffman coding ("squeezed"). Each 8-bit byte (after run-
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length encoding) is encoded by a variable number of bits, with
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bit length (approximately) inversely proportional to the
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frequency of occurence of the corresponding byte.
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4. LZW compression ("crunched"). Variable-length strings
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of bytes (in theory, up to nearly 4000 bytes in length) are
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represented by a single (maximum) 12-bit code (after run-length
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encoding).
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5. LZW compression ("squashed"). This is a variation of
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crunching which uses (maximum) 13-bit codes (and no run-length
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encoding).
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Since one of the five methods involves no compression at all, the resulting
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archive entry will never be larger than the original file.
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The last release of the MS-DOS ARC program (version 5.20) has eliminated
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squeezing as a compression technique. However, UNARC continues to
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process squeezed files for compatibility with archives created by earlier
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versions of ARC and by other MS-DOS archiving programs (notably PKARC).
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The squashed compression method was introduced by the MS-DOS programs
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PKARC and PKXARC. UNARC can process files which use this method,
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although it is not universally accepted by other MS-DOS archive extraction
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programs (including ARC).
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During its lifetime, the ARC program has undergone numerous revisions
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which have employed different variations on some of the above methods,
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particularly LZW compression. In order to retain compatibility with
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archives created by earlier program revisions, ARC stores a "version"
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indicator with each file in an archive. Based on this indicator, the latest
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release of the ARC program can always extract files created by older
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releases (although it will only use the latest data compression versions when
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adding new files to an archive).
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The current release of UNARC supports archive file versions generated by
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all releases of the following MS-DOS programs through (at least) the
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indicated program versions:
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ARC 5.20 (24 Oct 86), by System Enhancement Associates, Inc.
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ARCA 1.22 (13 Sep 86), by Wayne Chin and Vernon Buerg
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ARCH 5.38 (26 Jun 86), by Les Satenstein
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PKARC 2.0 (15 Dec 86), by Phil Katz (PKWARE, Inc.)
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UNARC does not recognize, but is unaffected by, the non-standard archive
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and file commenting feature of PKARC.
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Although the above discussion has emphasized the origin of archive files
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for the MS-DOS operating system, their use did spread to many other
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systems. Programs compatible with MS-DOS ARC have appeared for UNIX,
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Atari 68000, VAX/VMS, and TOPS-20 systems. A CP/M utility for building
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archive files is also available.
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For additional information about archive files and the MS-DOS ARC utility,
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refer to the documentation file, ARC.DOC, which is available on the web.
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For additional information about the LZW algorithm (and data compression
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methods in general), refer to the article "A Technique for High-Performance
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Data Compression", by Terry A. Welch, in IEEE Computer magazine, Vol. 17,
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No. 6, June 1984.
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