options.doc

/* derived from: options.doc 1.4 88/08/22 15:24:59 */
/* $Source: /usr/home/dhesi/zoo/RCS/options.doc,v $ */
/* $Id: options.doc,v 1.5 91/07/09 02:53:10 dhesi Exp $ */

Documentation about the file options.h.

The file options.h defines various symbols and macros that are needed
to ensure system-independence.  The basic philosophy is to use a
distinct symbol for each attribute that varies from machine to machine.
Then, for each new system, we define symbols corresponding to its
attributes. Thus, ideally, the only place in Zoo code that we actually
use the name of a machine is in this file, in portable.h, and possibly in
machine.h and options.c.  Everywhere else in the code we only use
names of attributes.

LOOK IN THE FOLLOWING FILES WHEN MAKING CHANGES TO SUPPORT A NEW SYSTEM:

	  options.h, portable.h, machine.c

ALSO GLANCE AT THESE FILES TO MAKE SURE THEY WILL WORK:

	  zooio.h, machine.h

Machine names:

MSC         Microsoft C under MS-DOS      (not currently in use)
TURBOC      Turbo C++ 1.0 under MS-DOS    (works, compiled version is
                                          separately distributed)
SYS_V       Most releases of System V     (works)
VMS         VAX/VMS 5.4                   (works, stream-LF files only)
BSD4_3      4.3BSD an most derivatives    (works)
MCH_AMIGA   AmigaDOS Aztec/Manx C         (not tested; compiled version
														 will eventually follow)


MERGED OR MIXED SYSTEMS.  Many vendors of **IX systems take one of the
two (System V or BSD) and add features from the other.  In some cases
they do a terrible job of reconciling irreconcilable differences between
the two, such that the merged system will now compile neither System V
stuff nor BSD stuff.  If you are dealing with such a system, try 
compiling with both BSD4_3 and SYS_V in turn, and see if one of them
works.  If not, then go through the list of compilation symbols below
and pick a set that matches your system.

------------------------------------------------------------------------
NOTE:  The term "zoofile" below refers to an open file of type
ZOOFILE.  Currently this is defined to be equivalent to a standard
buffered file pointer of type "ZOOFILE *" but this could change in the
future.  Dependence on exact definition of ZOOFILE is localized to a
few files:  options.h, portable.h, portable.c, and machine.c.
------------------------------------------------------------------------

Attributes of systems:

CHEKDIR
   Test each supplied filename and if it is a directory or other special
   type of file, do not try to add it to an archive.  If CHEKDIR is
   defined, then machine.c must also contain function isadir() that
   tests a supplied zoofile and returns 1 if it corresponds to a
   directory or other special type of file, else 0.
CHEKUDIR
   Like CHEKDIR but use function isuadir() that tests a pathname, not
   a zoofile.  Both CHEKDIR and CHEKUDIR may be defined, if both
   functions isadir() and isuadir() are available;  in this case
   zoo code will use both and will execute slightly faster.
   (However, simultaneous definition of CHEKDIR and CHEKUDIR has
   not been tested.)
DISK_CH
   If defined, must hold the value of a character that separates a
   disk name from the rest of the pathname.  All characters up to and
   including this character will be removed from a pathname before it
   is stored in an archive.  Usually a colon (':').
EXISTS
   If defined, is assumed to be a macro that accepts a filename and
   returns an int value of 1 if the file exists and 0 if it doesn't.
   If not defined, existence of files is tested by attempting to open
   them for read or write access.
FATTR
   If defined, file attributes will be preserved.  A function
   getfattr(f) must also exist that returns the attributes of a
   zoofile f (or of a pathname f, if the symbol FATTR_FNAME is
   also defined); and a function setfattr(f, a) must exist that
   sets the attributes of a file with pathname f to the value a.
   For more details see the source code in sysv.c and bsd.c.  Currently
   the attribute value a is required to be in the zoo portable
   format.  The lowest nine bits of this format correspond to
   the **IX mode bits described for chmod(2) and these are the only
   bits currently used.
FATTR_FNAME
   If defined, and if FATTR is also defined, zoo code will
   obtain the attributes of a file by calling the function
   getfattr(f) and supplying it with filename f.  If FATTR_FNAME
   is not defined, then getfattr(f) is supplied a zoofile f.
ANSI_PROTO
   Use ANSI-style function prototypes declarations.
VOIDPTR
   The type of a generic pointer, as returned by malloc().  This
   should be defined as void * in an ANSI C environment.  In most
   other environments it will be char *.
LINT
   If defined, SCCS identifier strings will not be included in the
   generated code.  This will make the code smaller and will also
   avoid complaints from lint about unused variables.  This symbol
   should be defined in the Makefile, NOT in `options.h', otherwise
   it will not be fully effective.
FOLD
   Fold filenames to lowercase.  Define this for case-insensitive filesystems
FPUTCHAR
   If defined, a library function fputchar() is assumed available
   that is like fput() but is a function, not a macro, to save
   space.  If not defined Zoo uses its own fputchar() function.
PORTABLE
   Use portable functions --- define for every system except MS-DOS
PURIFY
   When filenames are being read from standard input, ignore all
   characters begining with the first blank or tab encountered.
   This will allow filenames to be fed from a program that produces
   lines containing filenames followed by other information that
   should be ignored.  Should be defined for most non-**IX systems.
DONT_SORT
   Don't sort filename arguments -- files will be stored in the
   exact order in which names are supplied on the command line.
   Not currently used for any system, but could be used if memory
   is really tight.
NOENUM
   Compiler does not support enumerations
FNLIMIT
   Pathname length limit for this system
NEEDCTYP
   If defined, tells the code to include the header file ctype.h for
   use by character conversion macros.  If and only if NEEDCTYP is not
   defined, macros or appropriate function declarations can be put in
   portable.h.  Zoo uses isupper(), isdigit(), toascii(), and tolower().
   If NEEDCTYP is not defined, the symbol USE_ASCII can be defined to
   cause zoo to assume the ASCII character set and use its own isupper(),
   isdigit(), toascii(), and tolower() functions, possibly making the
   executable code smaller.
USE_ASCII
   See description of NEEDCTYP.  USE_ASCII should not be defined if
   NEEDCTYP is defined, else there may be conflicts between macro
   and function names.
NIXTIME
   If defined, a function setutime() must be defined that will set the
   date and time of a file whose pathname is supplied.  If not defined,
   a function settime() must be defined that will do the same for
   a zoofile.
GETUTIME
   If defined, a function getutime() must be defined that will return
   the MS-DOS format date and time of the specified filename.  If this
   symbol is not defined, then a function gettime() must be defined
   that will do the same for a zoofile instead of a filename.
NOSIGNAL
   Don't use signals because library doesn't support them
T_SIGNAL
   The data type returned by a signal handler.  Historically
   "int", but "void" in ANSI C.
PATH_CH
   The character that separates the directory name from the filename
   in a pathname.  String value.
PATH_SEP
   The set of characters that may separate preceding directory/device
   information from the filename.  String value.
EXT_SEP is the union of PATH_SEP and the set of characters separating a
   filename extension from the rest of the filename.  String value.
EXT_CH
   Character that separates base part of filename from extension.
   Char value.
NEED_MEMSET  If defined, zoo will define its own equivalent of memset().
	if not defined, zoo will try to link with a standard library function
	memset().
EXT_DFLT
   default extension for archives.  String.  Currently ".zoo".
NIXFNAME
   If defined, PATH_CH, PATH_SEP, EXT_SEP, EXT_CH, and EXT_DFLT get defined
   to conform to **IX conventions and should not be separately defined
MSFNAME
   if defined, PATH_CH, PATH_SEP, EXT_SEP, EXT_CH, EXT_DFLT, and
   DISK_CH get defined to conform to MS-DOS conventions and should
   not be separately defined (not currently implemented)
FORCESLASH
   If defined any backslashes in names of files will be converted to
   slashes before the files are added to an archive.  This is useful
   for MSDOS-like systems that accept both slashes and backslashes,
   since the standard archive format allows only slashes as directory
   separators.
REN_LINK
   Rename a file by using link() followed by unlink() (e.g. Xenix, System V)
REN_STDC
   Use ANSI standard rename function:  "int rename(old, new)" (e.g. 4.3BSD,
   Turbo C).  Note:  define exactly one of REN_LINK, REN_REV, and REN_STDC.
REN_REV
   Use reverse rename function:  "int rename(new, old)" (e.g. Microsoft C)
SETMODE
   Change mode of standard output to binary when piping output, then change
   it back to text.  Macros MODE_BIN(zoofile) and MODE_TEXT(zoofile) must
   also be defined.  Probably specific to MS-DOS.
SETBUF
   Standard output should be set to be unbuffered so output shows up
   quickly.
SPECNEXT
   If defined, a machine-dependent function nextfile() must be defined that
   will expand wildcards in a supplied pathname. If not defined, any
   wildcard expansion must have been done before the command line parameters
   are supplied to the program.  For details see the file nextfile.c.
SPECEXIT
   Custom exit handler is needed.  A function called zooexit()
   must be defined.  If SPECEXIT is not defined, zoo uses its
   own zooexit() function which simply calls exit().
SPECINIT
   If defined, zoo's main() function will call spec_init() before
   doing anything else.  Any system-specific initialization may be
   done at this point.
GETTZ
   If defined, a function gettz() must also be defined that will
   return the current timezone, in seconds west of GMT, as a long
   value.  Currently such a function is already defined in files
   bsd.c and sysv.c.  If and only if GETTZ is defined, zoo will
   store the current timezone for each file that is archived,
   and will list the timezone for each file that has one when it
   lists archive contents.
ALWAYS_INT
   In function prototypes for fgetc(), fread(), and fwrite(),
   traditional practice made certain arguments int, though
   they ought to be char and unsigned respectively.  If
   ALWAYS_INT is defined, prototypes will use int only,
   else the correct types are used.
NO_STDIO_FN
   Defining this symbol will cause declarations of fputc(),
	fread(), and fwrite() to not be done by the zoo header files.
	Reported necessary for VMS;  may also help in other environments.
IO_MACROS
   If defined, some portable I/O functions are defined as macros,
   saving space.
ZOOCOMMENT
   If defined, archive comments are fully enabled.  If not defined,
   zoo code will be smaller at the cost that archive comments will
   be listed but cannot be updated.  COMPILATION WITHOUT ZOOCOMMENT
   DEFINED HAS NOT YET BEEN TESTED.
TRACE_IO
   This is for debugging.  If defined, it will cause code to
   be compiled that will trace all archive header and directory
   entry I/O by showing it on the screen in human-readable format.
   The tracing will then occur if any Expert command given to zoo
   is preceded by a colon.  E.g., if compiled with TRACE_IO on and
   given the command "zoo :l xyz", zoo will give a directory
   listing of xyz.zoo exactly as it would with "zoo l xyz" except
   that all archive header and directory entry reads and writes
   will be shown on the screen.  The tracing code is localized
   to the files zoo.c and portable.c, so just these two files
   can be compiled afresh when TRACE_IO is turned on or switched
   off.  NOTE:  The symbol TRACE_LIST, internal to the file
   "zoolist.c", enables debugging information too.  Do not define
   both TRACE_IO and TRACE_LIST because (a) a symbol conflict will
   occur and (b) the debugging information will be duplicated.
UNBUF_IO
   If defined, some I/O is done using low-level system calls read() and
   write().  To do this, the low-level file descriptor is synchronized with
   the buffered zoofile before such I/O is done.  To do this, read(),
   write(), and lseek() system calls must be available and the fileno()
   macro must return the file descriptor for a buffered file.  This is
   not portable and should definitely not be done by most end users.  If
   UNBUF_IO is defined, also defined must be a symbol UNBUF_LIMIT with a
   numerical value that specifies the threshold over which unbuffered I/O
   should be used.  For example, if the value of UNBUF_LIMIT is 512, then
   any I/O on a zoofile that reads or writes more than 512 bytes will be
   done using read() or write() system calls.  The use of unbuffered I/O
   with a threshold in the range 512 to 1024 can enhance performance by up
   to 50%.  The corruption of data is a serious matter.  Do not define
   UNBUF_IO unless you are willing to exhaustively test the compiled code
   on your system to make sure it works, and accept full responsibility for
   any adverse consequences.  Some standard I/O libraries may attempt to
   optimize the working of fseek() on files opened for read access only,
   and cause UNBUF_IO to fail.
UNBUF_LIMIT
   Needed if and only if UNBUF_IO is defined.  Holds a numeric value.
   All I/O done in blocks that are larger than UNBUF_LIMIT bytes
   will be done unbuffered.  See UNBUF_IO.
FILTER
   If defined, code will be compiled in to enable the fc and fd
   commands (compress or decompress, reading standard input and
   writing to standard output).  These commands are useful only
   on systems that allow programs to easily act as filters.
VER_DISPLAY
   The character that will separate filenames from generation numbers
   in listings of archive contents.  Must be a single character
   in double quotes.
VER_INPUT
   The characters that will be accepted as separating filenames
   from generation numbers when typed as an argument to select
   specific files from an archive.  String value.  May include
   one or more characters;  any of them may then be typed and
   will work.
NOSTRCHR
   Although 4.3BSD as distributed from Berkeley includes strchr()
   and strrchr() library functions, 4.2BSD and similar systems
   may not.  If so, defining NOSTRCHR will cause zoo to use
   index() and rindex() instead.
STDARG, VARARGS.  How to invoke functions that accept a variable
   number of arguments.  Define one of these.  STDARG causes the
   ANSI-style header stdarg.h to be used.  VARARGS causes the **IX-style
   varargs.h header to be used.  If you define STDARG, you must also
   define ANSI_PROTO (see above).
DIRECT_CONVERT.  Zoo archives use a canonical little-endian byte order,
   and functions are portably defined to convert between this and the
   internal format used by an implementation.  If the symbol 
   DIRECT_CONVERT is defined, the zoo code will not bother doing this 
   portable conversion, but simply assume that the machine's internal
   format is the same as the canonical byte order used in zoo archives.
   DIRECT_CONVERT should be defined *only* if your implementation uses:
   little-endian byte order, 2-byte ints, and 4-byte longs.  If there is
   any doubt whatsoever, don't define DIRECT_CONVERT;  the overhead of
   portable conversion is not significant.
SZ_SCREEN.  If this symbol is not defined, a screen height of 24 lines
	is assumed by the multiscreen help.  If desired, this symbol can be
	defined to some other nonnegative value of screen height.
NEED_MEMMOVE.  If defined, zoo will define its own equivalent of memmove().
	If not defined, zoo will try to link with a standard library function
	memmove().
NEED_VPRINTF.  If this symbol is defined, zoo will use its own jury-
	rigged vprintf function.  If this symbol is not defined, zoo will
	try to link with vprintf in the standard library.