OS/2 Professional

home *** CD-ROM | disk | FTP | other *** search

/ OS/2 Professional / OS2PRO194.ISO / os2 / packer / polyxarc / polyxarc.doc < prev next >

Wrap

Text File | 1994-02-03 | 40.6 KB | 856 lines

page 1 PolyXarc v2.1 5 April 1991 Public domain by Jeffrey J. Nonken OS/2 port by Bill Andrus By giving this away, complete with source code and docs, I hope to encourage others to do likewise. I think we can all gain in the long run by sharing. Public Domain means that nobody owns it. You can give it away, sell it, incorporate bits into other programs, whatever you want. However, in the interests of program management, I request that if you make changes that may benefit others, you 1) Share them with us; 2) Send me a copy of source so I can make an 'official' release. Warranty: none. Address netmail to 1:273/715 in Fidonet. If you wish to log on, call (215)279-9799 (300/1200/2400/9600/14400 HST/V.32), PCPable. You can get the latest distribution version of PolyXarc by file requesting POLYXARC from 1:273/715. If you wish to send anything via U.S. Snail, write to: Jeffrey J. Nonken 1706 Cherrie Circle Blue Bell, Pa. 19422-3412 NOTE: Version 2.0 has major changes in the configuration file syntax. VERSION 1.x CONFIGURATION FILES WILL NOT WORK WITH 2.x! I have made no attempts to detect old configuration files and provide correction or warning; that would complicate and enlarge PolyXarc unnecessarily. It is up to you to make sure your configuration files have been replaced or updated. Version 2.0 configuration files will work just peachy with version 2.1. WHAT IT IS ========== "Poly" means "many", and "Xarc" means "archive extractor". PolyXarc is a program that permits automatic extraction of most known archive formats. By "Xarc" I do not specifically refer to SEA's ARC or XARC programs or the file format supported by ARC (which I will refer to as ".ARC format" herein), although PolyXarc supports both. The purpose of this program is to allow Fidonet BBS system operators to automatically extract bundles that have been made with various archive programs. Traditionally sysops have used one .ARC format program or another. But recent improvements in compression techniques, along with a rapidly climbing volume of echomail, have encouraged sysops to look at other programs. It is not my purpose to praise or encourage the use of one archive format over another. In fact, the whole purpose of PolyXarc is to support as wide a variety as possible. PolyXarc 2.1: multiple-format archive extractor executive page 2 PolyXarc does not itself extract archive files; PolyXarc identifies which format is being used and calls on the appropriate archive extractor program to do the actual work. In this lies its flexibility. Think of PolyXarc as an "Archive Extractor Executive". PolyXarc is a direct replacement for SPAZ v1.40 (developed by Dan Thomson and Andrew Farmer), except that PolyXarc is much larger (about 35k vs. 6k) and may not work in cases where memory is at a premium. However, PolyXarc is more versatile and much more flexible. PolyXarc's main features are: - Automatic stand-alone mail bundle extraction; - Small and fast; - Flexible and adaptable. PolyXarc can find all mail bundles in a specified directory and de-archive all of them. In addition, PolyXarc can sort version 5 .ARC files by their date/timestamps before beginning extraction to assure that the packets are, as much as possible, extracted in the correct order. PolyXarc also gives you the choice of limiting the number of archives that it extracts in a session so that you can process them a few at a time instead of all at once. I tried to write PolyXarc to be as flexible and expandable as I could within reason. Unlike most multi-archive mail unbundlers, except for some .ARC format recognition, PolyXarc does not have any specific format recognition built in. Instead, PolyXarc has a configuration file that contains signature strings and command line templates, allowing you to expand PolyXarc's capabilities without having to write any code. In addition, you can customize PolyXarc's recognition of .ARC format compression flags, and tell it which program to use for which flag. However, if all else fails, and you come upon a format for which PolyXarc cannot be configured, you can alter the source to accomodate it, for I have released the source code to the public domain. This gives unlimited permission for anybody to alter it, providing a permanent upgrade path. If the explanations in this document don't make sense, take a look at POLYXPLN.DOC; it picks apart the config file and explains some details about the archivers. HOW TO USE IT ============= PolyXarc's syntax is: PolyXarc [switches] archive [name [name...]] [switches] Recognized switches are: -Cconfig -I -O -D -Maddr -R -F[n] -N -Q -# PolyXarc 2.1: multiple-format archive extractor executive page 3 archive This is the name of the archive file you wish to extract from, or if you specify the -F switch, the path where mail bundles are kept. In the former case (not using -F) wildcards are supported, and if you do not supply an extension, PolyXarc will assume an extension of ".*". In the latter case (using -F), you must specify a path ONLY, not a file name. Also, if you specify -F you may leave the archive path out completely and it will default to the current directory. name... This is one or more names of files within the archive. If you list more than one name, they should be separated by spaces. These are optional. If left off, most extractors will assume that you want to extract all files. You must list the archive name (above) before listing individual file names. PolyXarc considers any parameter that does not start with a switch character ('-' or '/') to be a file name or archive name. -Cconfig This is the file that contains signature information for PolyXarc. If it is not in your current subdirectory you must supply a path to it as well. The file name must follow the switch with no intervening spaces. If you do not specify -C on the command line, PolyXarc will look first for POLYXARC.CFG in the current directory, then in the directory of the .EXE file, and if not found will then look for a PENGUIN file (described later). -D Specifying this will cause PolyXarc to delete any archive file it successfully has extracted. Specifying the /F parameter causes /D to be enabled unconditionally. -F[n] -F will cause PolyXarc to extract all the mail bundles it can find in the subdirectory specified by 'archive'. If you specify a number after the F (like "-F2"), PolyXarc will extract up to that number of mail bundles. In this case 'archive' (above) must be a path, not a filename. Specifying -F also forces -D and -O, and disables -N. -I I really mostly intended this for use in some manual modes. This switch will cause PolyXarc to ignore errors returned from the archivers. PolyXarc 2.1: multiple-format archive extractor executive page 4 -Maddr This causes PolyXarc to calculate and display the net address of the sender of each bundle. 'addr' is your netmail address, net and node only. Example: -M273/715. -N Specifying this causes PolyXarc not to attempt to sort an .ARC format file. Normal action is to sort all .ARC format files (the files inside the archive) by the date and time stamps. Specifying -F will override -N and cause PolyXarc to sort the files. Note that PolyXarc will not sort ARC version 6 files. -O This is the overwrite flag. If the archiver finds that a file it is extracting already exists, this flag will cause it to overwrite the old file without prompting. Specifying the -F parameter causes -O to be enabled unconditionally. -R This is the same as -O. I included it to maintain ARCE syntax compatibility for people who want to call PolyXarc from within other programs (such as Opus 1.0). -Q Specifying -Q causes PolyXarc not to display most status and configuration messages. Error messages will still be displayed. -# Normally when you invoke the -F switch, PolyXarc will unbundle files with extensions starting with .MO, .TU, etc. and ending with any character. If you add the -# switch, PolyXarc will only unbundle files ending with a decimal digit (0-9). NOTE: None of these switches is position dependent or case sensitive. Any may be specified with a hyphen (-) or a slash (/). If you specify a question mark (?) as the first parameter, you will get a brief help message and no processing will be done. PolyXarc requires a single configuration file. This file gives PolyXarc enough information to recognize various archive formats by looking for specific 'signatures'. There are three ways to specify the configuration file name: - just have POLYXARC.CFG in the current directory, or in the directory with POLYXARC.EXE; - use the -C switch to specify it on the command line; - use a PENGUIN file. PolyXarc 2.1: multiple-format archive extractor executive page 5 Doug Boone has proposed an idea that I like; rather than proliferate configuration files, gather as many as possible into one file. His implementation requires you to specify the file in an environment variable called PENGUIN. PolyXarc may use the PENGUIN technique if you have set the environment variable. This is how PolyXarc decides which technique to use: if you specify a file on the command line using the -C parameter, PolyXarc will use that file. If you don't specify the -C parameter, PolyXarc will look for POLYXARC.CFG in the current directory. If it doesn't exist, PolyXarc will then look in the directory that it was executed from. If it isn't there either, PolyXarc will look for the PENGUIN environment variable. If it exists, PolyXarc will use that file; otherwise, it will exit with an error. To set the environment variable, you would put a statement like this into your AUTOEXEC.BAT file: SET PENGUIN=D:\OPUS\PENGUIN.CFG There are three keywords that PolyXarc recognizes in the configuration file, one of which has three variations, plus BEGIN and END statements. PolyXarc will not recognize any keywords until it sees a BEGIN POLYXARC statement, and will ignore anything after an END POLYXARC statement until it sees another BEGIN POLYXARC, if any. You may have as many of these blocks as you want in the configuration file, and they may overlap other programs' blocks if you wish. PolyXarc will ignore anything it doesn't recognize. The keywords are: ARC ARC5 (same as ARC) ARC6 SIGNATURE NOSORT Before I describe the keyword syntaxes, let me explain the command templates they use. A command template is a description of the command line used to call a certain program. The general syntax of a command line consists of the command, followed by one or more parameters, the overwrite flag key, the extract flag key, the filename key, and/or the extractname key. The parameters and keys may be in different orders depending on the syntax of the particular archive extractor you are using. The command is the actual DOS command used to run the program (such as "ZOO" or "ARCE"). The parameters are any parameters needed to cause an extraction. The extract flag key is actually an 'insert flag' that tells PolyXarc where to put the extract switch if it is needed. The extract flag key is "%1". The overwrite flag key, "%2", tells PolyXarc where to put the overwrite switch if it is needed. The filename key, "%3", is the name of the archive to extract from, and is also an insert flag. The extractname key, "%4", is a list of names of files to extract PolyXarc 2.1: multiple-format archive extractor executive page 6 from the archive. Another way of looking at it is that you take the general syntax for the particular archiver, put a %1 in place of the extract switch (if any... most archivers will not actually use this field), a %2 in place of the overwrite switch, a %3 in place of the archive filename, and a %4 where the list of files would be if you wanted to specify which files to extract. The actual order of these parameters depends on what each particular archiver expects to see. As mentioned above, most extractors will not need the extract flag key. In most cases, the extractors have an extract command (either explicit or implied) that is used whether you want automatic overwrite or not; to overwrite, you use the overwrite command in addition to the extract command. I have not seen any archive extractor that uses a separate command for extract- without-overwrite versus extract-with-overwrite; nevertheless, I would rather include support for a redundant parameter now than have to 'fix' it later. In any case, the extract flag key will only be used if overwrite option is not invoked on PolyXarc's command line, and the overwrite flag key will only be used if the overwrite option is invoked. If there is an extract command that is used whether or not overwrite is invoked, then you should include it as a permanent part of the template for that command. General syntax for the ARC keywords: ARC level overwrite extract command_template ARC5 level overwrite extract command_template ARC6 level overwrite extract command_template PolyXarc recognizes .ARC format files internally. The ARC command spec defines a level (known as a 'header type' by the .ARC compatible programs) at which a certain program should be executed. ARC programs will generally extract any level of compression up to the level they are capable of. For example, ARC version 5 and ARCE will extract up to level 8; ARC version 6, PKXARC, and PKUNPAK will extract up to level 9; PAK will extract up to level 11. Specify the appropriate level for each extractor you will be using. Note that you need not supply all the extractors you have available; for example, PAK will extract all your version 5 .ARC files. However, due to speed or memory you may want to specify several archivers so that the smallest or fastest may be used whenever possible. ARC version 6 is a special case. SEA introduced an extended header format that allows non-file information to be added. Version 5 programs such as PKPAK and PAK cannot deal with these formats and will exit with an error if you try to use them on version 6 files. Version 2.0 of Polyxarc also does not know how to deal with these files. However, even version 6 ARC files have different levels, and PAK, a strictly version 5 archiver, uses compression levels that are incompatible with ARC version 6 ARC+PLUS. So if PolyXarc 2.1 detects version 6 information in an .ARC file, it will look for an archiver with an ARC6 keyword. PolyXarc 2.1: multiple-format archive extractor executive page 7 ARC version 6 programs can extract version 5 files. Unfortunatly, PAK level 10 is incompatible with ARC+PLUS level 10. So PolyXarc tries to use version 5 archivers for version 5 files if they are specified. If no version 5 archiver in your config file will extract the version 5 archive, PolyXarc will attempt to apply a version 6 archiver to the file. Note that PolyXarc will never attempt to use a version 5 archiver to extract a version 6 archive. Please note that unlike PolyXarc version 2.0, PolyXarc version 2.1 does not need the .ARC format signature lines listed in any particular order. Version 2.1 now automatically sorts the signatures once it reads them in. All you have to do is get the levels and versions right. If this is confusing to you, imagine how difficult it is trying to describe it! But if you use the commands in the distributed POLYXARC.CFG file you should be ok. You may also read POLYXPLN.DOC for some more detailed explanations. An example of mixed ARC lines (remember, ARC and ARC5 are the same): ARC5 8 /r "" arce %3 %4 %2 ARC 11 /WA "" pak /e %2 %3 %4 ARC6 10 /o "" xarc %2 %3 %4 Ok, back to the syntax descriptions. A reminder of what the signature lines look like: ARC level overwrite extract command_template ARC5 level overwrite extract command_template ARC6 level overwrite extract command_template Overwrite is the parameter this particular archive program needs in order to automatically overwrite existing files while extracting. The overwrite parameter must be 5 characters or less. Extract is the parameter this particular archive program needs in order to extract files. This is only used for programs which use different commmands for 'extract' and 'extract overwrite'. The extract parameter must be 5 characters or less. In most cases you will not need the extract parameter. However, there must be something defined for each field, whether it is used or not. In my distributed configuration file I simply put in an empty string ("") as a place holder. The command template defines the command line (including the name of the arc file) used to invoke the necessary de-archiver. Here are some examples from the distributed configuration file: PolyXarc 2.1: multiple-format archive extractor executive page 8 ARC 8 /r "" arce %3 %4 %2 ARC 9 /r "" pkunpak %2 %3 %4 ARC6 10 /o "" xarc %2 %3 %4 ARC 11 /WA /WO pak /e %1%2 %3 %4 Here is the PAK command line that PolyXarc might generate, first with overwrite enabled, then without: pak /e /WA 0000FFFB.MO2 pak /e /WO 0000FFFB.MO2 Here is the PKUNPAK command line in the same order: pkunpak /r 0000FFFB.MO2 pkunpak 0000FFFB.MO2 General syntax for the SIGNATURE keyword: SIGNATURE type offset signature overwrite extract template This command allows PolyXarc to automatically recognize different compressor archive formats without being locked into any particular format or set of formats. Note that you should not try to define a SIGNATURE for .ARC format files, as they are recognized internally. The different signatures will be looked for in order of definition, with .ARC files coming last. Offset is the offset into the file of the signature. If offset is preceeded by a '-' (minus sign), PolyXarc will count backwards from the end of the file. Signature is the text of the signature. The signature parameter must be 5 characters or less. Overwrite is the parameter this particular archive program needs in order to automatically overwrite existing files while extracting. The overwrite parameter must be 5 characters or less. Extract is the parameter this particular archive program needs in order to extract files. This is only used for programs which use different commmands for 'extract' and 'extract overwrite'. The extract parameter must be 5 characters or less. In most cases you will not need the extract parameter. However, there must be something defined for each field, whether it is used or not. In my distributed configuration file I simply put in an empty string ("") as a place holder. The command template defines the command line (including the name of the arc file) used to invoke the necessary de-archiver. PolyXarc 2.1: multiple-format archive extractor executive page 9 Here are some examples from the distributed configuration file: SIGNATURE -3 DWC w "" dwc e%2 %3 %4 SIGNATURE 2 -lh /mc "" lharc e %2 %3 %4 SIGNATURE 0 ZOO O "" zoo x%2 %3 %4 SIGNATURE 0 PK -o "" pkunzip %2 %3 %4 SIGNATURE 0 PK /WA /WO pak /e /z %1%2 %3 %4 SIGNATURE 0 <60EA> -y "" arj e %2 %3 %4 An expanded Zoo command line would look like this, first without, then with overwrite: zoo x 0000FFFB.MO2 zoo xO 0000FFFB.MO2 The NOSORT keyword syntax is: NOSORT If specified, NOSORT causes PolyXarc not to attempt to sort .ARC format files. (Notice that PolyXarc will not attempt to sort version 6 archive files in any case. That is because only one obsolete version 5 program, PKARC/PKPAK, sorts alphabetically when adding to an archive, and because some extended version 6 headers are position dependent.) This is almost identical to the -N switch on the command line. If neither is specified, PolyXarc will attempt to sort the files in .ARC format archives by date and time in order to keep mail packets in chronological order. This is in case the sender used PKPAK or PKARC to pack his mail; they will sort the files in the archive alphabetically, which occasionally causes messages to get out of order. Note that while the -F switch will override the -N switch, the NOSORT keyword overrides the -F switch, causing PolyXarc never to sort. PolyXarc allows some special character sequences in the config file. The two main sequences are: quoted strings, and hex numbers. These are a lot easier to use than to explain, but if you want to skip ahead there is a summary at the end of this explanation. Normally PolyXarc just treats a character as a character. For example, this line: SIGNATURE 0 PK /WA /WO pak /e /z %1%2 %3 %4 is interpreted exactly as you would think. One or more spaces or tabs separate each parameter on the line. Since the template is the last parameter on the line, we always know where it starts, and everything after that is part of the template, so we can imbed spaces into the template with impunity. However, there are times when you may need to imbed spaces into a parameter other than the template. In that case you must enclose the parameter in quotes. For example, if you had a signature with a space: NEW 1 PolyXarc 2.1: multiple-format archive extractor executive page 10 You would have to put quotes around it in the config file, something like this: SIGNATURE 0 "NEW 1" -o -e NEW %1%2 %3 %4 This also allows you to include an empty string in the config file. For example: SIGNATURE 0 PK -o "" pkunzip %2 %3 %4 Notice that instead of an extraction parameter, there are two double-quotes. PolyXarc sees the quotes and knows there's a parameter there, but since there's nothing between them, PolyXarc will store an empty string. That way if you accidentally include that parameter in the template, nothing will happen; and even if you don't, the parameter will not take up any room in memory. Note that you don't have to put the whole string in quotes. For example, you can put "NEW 1" as NEW" 1"; once PolyXarc sees the first quote, it will continue ignoring spaces until it sees the second quote. Also note that you MUST have a closing quote, or PolyXarc will keep going until the end of the line, and the rest of the parameters on that line will be lost. Besides using quotes, you can also imbed hex numbers in a parameter instead of just using printable characters. For example: SIGNATURE 0 <60EA> -y "" arj e %2 %3 %4 This program's signature consists of two characters, one of them unprintable, at the beginning of the file. Instead of making you try to imbed the second character directly into the config file with a fancy editor, I've allowed you to describe the character by giving its ASCII value in hexadecimal. When PolyXarc sees a less-than character (<), it goes into Hex mode and starts interpreting the following characters as hex numbers, until it sees a greater-than character (>) or reaches the end of the line. Notice that this is like the quote feature, in that you don't have to make the entire parameter hex if you have some printable characters. In the example above, the first character is actually printable; you could define it like this instead: SIGNATURE 0 `<EA> -y "" arj e %2 %3 %4 Now there are a few more rules for hex digits. First of all, PolyXarc expects that the hex digits will be in pairs. One pair of digits describes a character. You can define an odd number of digits, but you may not get the results you expect. For example, <615> is not the same as <0615> or <6150>; it is the same as <6105>. Your best bet is to use character pairs, or see the next rule. PolyXarc 2.1: multiple-format archive extractor executive page 11 Another rule is that anything that isn't a (>) or a hex digit will break a character description, assume that it's finished, and start on the next character. For example, <6 15> is the same as <0615> is the same as <06 15> is the same as < 6,15>. The spaces and commas act as separators. This provides a handy visual breakup. Now, it is possible that you will want to have the characters " or < in one of your signatures. To accomodate that I added the "literal" character, which is a backslash (\). When encountered in normal mode or inside a quote, the backslash tells PolyXarc to take the next character literally. This way you can imbed the quote or less-than characters without having to go into hex mode and describe them in hex. If you want to imbed a backslash, simply include two backslashes: \\. PolyXarc will see the first one as a directive ("take the next character literally") and then take the second one as a character. Limitations: You cannot change modes between hex and quoting in the middle of a quote or hex sequence. If you are in a hex sequence and want to start a quote you must first end the hex sequence. If you are in a quote string you cannot imbed a hex sequence; you must end the quote. A '<' in the middle of a quote is treated as a normal character. For example: <4142> converts to "AB" <41>B converts to "AB" A<42> converts to "AB" "A"<42> converts to "AB" <41>"B" converts to "AB" "A<41>" converts to "A<41>" <41"B"> converts to "A." (where . is actually an unprintable character with a numeric value of 0B) Here is a summary of the rules: - A whitespace character is a space or tab. - Normally, each non-whitespace character is simply treated as a character. - If you place double-quotes (") around a string or part of a string, that string will be accepted intact, including whitespace. - If you imbed a backslash ('\'), the backslash will be thrown away and the next character will be accepted as a character. This allows you to imbed the double-quote (") and less-than (<) characters as regular characters. To use a backslash as part of a string you must imbed two backslashes ('\\'); this will translate to a single backslash. - If you place a less-than sign (<) in a string, the following characters will be considered to be 2-digit hex numbers until a greater-than sign (>) is reached. A hex digit is any numeric digit (0-9) or any letter from A to F (a-f or A-F). Normally the hex digits will be taken in pairs, but if any other character is imbedded, it will be considered to be a number break and the next digit will start the next number. PolyXarc 2.1: multiple-format archive extractor executive page 12 TECHNICAL SECTION ================= PolyXarc figures out what format is being used by looking for certain characteristics in the file. For example, each PKZIP format file has "PK" as the first two bytes in the file. All .ARC format files have a hex 1A value as the first byte. The SIGNATURE lines in the configuration file describe what to look for, where to look for it, and what command syntax to use if PolyXarc finds it. ...except for .ARC files. Over the years .ARC files have added a number of different formats. Each time one is added, it gets assigned a level. The standard programs (ARC, ARCA, and ARCE) support up to level 8. PKPAK added level 9, and PAK added levels 10 and 11. Due to program size and other considerations, people often prefer to use the minimum program required for the job. Also, some archive extractors are faster than others. Either way, the ARC lines in the configuration file describe what to look for, and what command syntax to use if PolyXarc finds it. Each ARC line has a level number. That number is the highest level that program will support, not just the only number. PolyXarc always uses the minimum specified program for the highest level found in the archive. The exceptions, as explained before, are ARC6 programs. Because they support an extended set of ARC formats, their archives are readily identifiable and are incompatible with version 5 archives. If you have both an ARC5 and an ARC6 program supporting a compression level, the ARC5 program will always be used for an ARC5 file using that level. An ARC6 program will always be used to extract an ARC6 file. EXAMPLES ======== I have my incoming and outgoing mail on two different drives. To optimize space usage on my outgoing drive, I have PolyXarc extract the archives into the incoming directory before I let QMail loose on them. Therefore my batch file looks something like this: C: CD \NET\FILE PolyXarc -F -M273/715 E: QM TOSS etc. If you want to run PolyXarc directly from Opus 1.0 on a barefoot Opus system, simply rename POLYXARC.EXE to ARCE.EXE. If you already have the real ARCE someplace on your system, make sure that the renamed PolyXarc is either earlier in the path, or replaces ARCE, or is in the directory you are running it from. Otherwise, it will quite likely find the original ARCE first. Remember also, if you have ARCE.COM and ARCE.EXE in the same directory, DOS will always run ARCE.COM. Also remember to either PolyXarc 2.1: multiple-format archive extractor executive page 13 remove the ARCE control line from PolyXarc's configuration file, or else specify ARCE's path in the control line; otherwise PolyXarc will end up trying to execute itself and you will end up with what is known in the business as 'a mess'. To use PolyXarc from Confmail, add the -A parameter to the end of Confmail's command line: Confmail import blah blah blah -A PolyXarc -o -m273/715 RETURN CODES &c. ================ 0 = No error. 1 = Can't open/read source (missing or invalid file). 2 = Can't create/write dest (maybe disk or directory full). 3 = Can't delete old source file (read-only). 4 = Can't rename temp file to source name. 5 = Out of memory. 6 = Cannot determine archive type. 7 = Configuration file syntax error. 8 = Error was returned from the archive extractor. 9 = File was zero-length. 10 = DOS error while trying to execute the extractor. Note that if you use the -f switch, not all of these errors will be returned. In the case of a zero-length file, PolyXarc -f will simply give a warning message, delete the file, and go on. In the cases of errors 3, 6 and 8, PolyXarc will rename the file to BAD_ARC.??? (where ??? is an ascending decimal number starting from 000) and go on. CAVEATS ======= If a file has been transferred via XMODEM, the last record of that file will be padded with nulls. In the case of DWC- compressed files, this can be a problem. Since PolyXarc looks for "DWC" at the end of the file, the null padding will cause PolyXarc not to recognize a DWC file. I could add enough smarts into PolyXarc to have it search backwards through the nulls. However, DWC is not used by many sysops, and there are other archivers that work just as well, so it doesn't seem worthwhile. This is a potential problem for any archiver whose signature is at the end of the file, though at the moment I don't know of any besides DWC. ACKNOWLEDGEMENTS ================ Thanks to Mike Housky for the entire .ARC format search-and-sort section. I shamelessly stole it straight out of his PAKSORT program. Thanks also to Dan Thomson for coming up with the original program, SPAZ, and saving me a lot of research and planning. (There is probably no easier program to design than one for which you have a working model!) PolyXarc 2.1: multiple-format archive extractor executive page 14 Many thanks to John Lull and Clay Tinsley, two of my original beta testers. They faithfully ran every revision I put out and let me know whenever something went wrong. (Which was often.) Clay was also responsible for convincing me to write PolyXarc. David Page, another beta tester, also gave some helpful criticism. Thanks to Steve Palm, who ported PolyXarc over to use on his Amiga, and Bill Andrus, who ported PolyXarc over to OS/2. Between us we came up with a set of source files and definitions that allow us to compile the same source under our respective operating systems. Thanks to Peter Stern for helping track down some subtle bugs in version 2.0. Thanks in no particular order to Thom Henderson, Phil Katz, Rahul Dhesi, David W. Cooper, Nogate Consulting, Haruyasu Yoshizaki, Vernon Buerg, Wayne Chin, Robert K. Jung, and all the other archive program authors for all their hard work. Keep it up, guys! And as always, thanks to Ward Christensen for everything. Jeffrey J. Nonken 1706 Cherrie Circle Blue Bell, Pa. 19422-3412 BBS: (215)279-9799 HST/v.32 Fidonet: 1:273/715 Internet: Jeffrey.Nonken@f715.n273.z1.fidonet.org Note: the above Snailmail address and phone number may change in the next few months. Please use my Fidonet or Internet address, or check the latest Nodelist for the current information. PolyXarc 2.1: multiple-format archive extractor executive