fixes

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

March 11, 1994

	If we are just plain old nroff (and not doing UNICODE) we should
	only Lookup characters, not Install when we don't know them.
	If we are troff, we Install them anyway

March 8, 1994

	Nroff had problems with parsing quoted white space as options or
	character code in some terminals tables. Changed by having scanf
	include white space when necessary as suggested by Rich.

March 1, 1994

	Made sanity check for terminal type depending on the trace level;
	trace level set with -tn flag at start up

22 Feb, 1994

	More pointer shuffling fixes.

18 Feb, 1994

	More disabling of multibyte stuff. Fixed bug in n5.c: casetm didn'
	know about the new format in the fontables.

Feb 17, 1994

	Removed extra include <setlocale> from n1.c

	Fixed dubious pointer shuffling in n7.c, t10.c & n8.c. Thanks Rich!

Feb 10, 1994

	Disabled the multybyte stuff; only plan 9 will get it.

Jan 24, 1994

	Fixed nasty bug discovered by td, which caused core dumps on
	\D'l-0.002775i 0i' and apparently all numbers closer to 0
	than -.002775. Fixed in storeline() and storeword() (n7.c).

Dec 16, 1993

	nroff & troff -N were looking for the TYPESETTER variable, causing

	troff: cannot open /sys/lib/troff/term/tab.202; line 1, file stdin

	fixed my moving getenv("TYPESETTER") to t10.c in t_ptinit(void).

Dec 3, 1993:

	The sequence \s+2\H'+10' came sometimes out in the wrong order
	(x H before s), so there wasn't a difference bewteen \s+2\H'+10'
	and \H'+10'\s+2. Now the fonts bits of the CHARHT are used to
	register the current pontsize, so we can issue a s10 in t10.c
	if needed. A bit sneaky.

	Try to prevent double slashes in path names. Especially under
	plan9 things started to look ugly.

	Exception word list now grows dynamic.

Nov 30, 1993:

	Allow multiple calls to .pi, requested by Rob.
		.pi cat
		.pi dogs
	is now equivalent with
		.pi cat | dogs


	.ab now takes also optional error code:
		.ab [n] [string]
	If n and string, n is exit code, string is message
	If n, n is exit code, ``User Abort, exit code n" is message
	If !n and string, standard exit code, string is message
	If !n and ! string, standard exit code, "User Abort" is message

Nov 24, 1993:

	Reordered code to keep the UNASNI scripts happy.

	Nroff dumped core reading terminal tables: apparenty under plan 9,
	scanf includes the '\n'; added test for '\0' in parse in n10.c.

	Relative tab settings (.ta +1C +2C) didn't work; anding the
	previous value with TABMASK fixes this (caseta).

Nov 23, 1993:

	Included code, originally done by bwk for plan 9, to handle
	multi-byte characters.

Nov 3, 1993:

	``pair internal'' two char names by shifting 16 bits. Will allow
	the use of 16 bit characters sets (Unicode in plan9 etc.) for
	macro's etc.

Oct 20, 1993:

	Word & line buffers are now dynamic: No more word or line overflow
	unless when we run out of memory.

Oct 11, 1993:

	lost diversion warning pops up regularly with man macro's. Due
	to a possible macro coding problem. Triggered by something like
	troff -man:
		.TP
		.TP
		foo
		.ex
    	Minimal code:
		.di aa
		throw away this diversion (aa) while being defined.
		.rm aa
		.br
		.di

	Fixed by disallowing .rm to throw away current diversion. The
	rn request will complain with:

		cannot remove diversion aa during definition; etc.

Sep 29, 1993:

	Some long standing fixes which never went back in the source.
	Thanks to Janet & Rich.

Sep 28, 1993:

	Changed getach() (n1.c), so it does't consider truncated
	special characters as (8-bit) ascii.  STX ETX ENQ ACK and BELL
	are still allowed for the ultimate backwards compatibility.

	Some code changes, so real ANSI compilers like the SGI version
	(acc from Sun is a poor excuse for an ANSI compiler) don't
	barf.  Some compromises (static Tchar wbuf in n9.c) allowed so
	the unansified stuff for non-ansi compilers (cc on Sun's) will
	work as well.

Sep 9, 1993:

	Be nice to Gerard. Now also word spaces in .tl and after
	tabs/fleids etc.

Aug 12, 1993:

	Tabs setting can now be humongous. We also allow 99 tabs to
	accomodate tbl. As a side effect, NTM buffers are now 1K

Aug 11, 1993:

	.R register, now contains maximum number of addessable
	registers minus the number actually used.

	Small esthetic changes in error messages; removed a statement
	which wasn't reached anyway.

Aug 10, 1993:

	Some more speed hacks: be smarter doing the linear table
	lookups in alloc() and finds().

	The real name of the det diversion size macro is now gd.

Aug 9, 1993:

	A much faster way to find the end of a string/macro, by
	remembering that when defined.

Aug 6, 1993:

	 Slightly more eficient way of skipping to the end of a
	 string/macro

Aug 5, 1993:

	Prevent character sign extension for 8-bit charnames diversions
	etc. by unpair

Aug 4, 1993:

	Growing the dynamical macro/strings name space and registers
	space (See the experiment of 21 July) now with bigger
	increments. Casts added to satisfy non-ANSI compilers.

Aug 3, 1993:

	Should check return value in alloc (n3.c), to prevent core dump
	when memory gets tight.

July 28, 1993:

	New request: .sg <div> sets the dn and dl registers to the size
	of the diversion named in the argument. Doesn't do anything
	when the named diversion doesn't exist. The name sg is
	temporary until we find a better one.

July 21, 1993:

	Experiment: Macro space  & registers name allocated
	dynamically. Note that current reallocation occurs in
	increments of 1, to force the code to be executed a lot; a kind
	of stress testing. Also, eight bit characters allowed in
	macro/string names.

July 21, 1993:

	Turn on the escape mode if the end macro is called.

July 20, 1993:

	Tracing mode now default off

	Don't print s stackdump either when a file specfied on the
	command line argument cannot be opened

July 15, 1993:

	Don't print useless line & current file informations when a
	file specfied on the command line argument cannot be opened.

	Sun ansi compiler doesn't default adhere to standards. Undid
	the kludge in tdef.h

July 14, 1993:

	Coding error made the tab type R not function properly

July 12, 1993:

	Fixed a typo in the version stuff, noticed by Rich

July 9, 1993:

	Added the dwb home configuration stuff, thanks RIch. Also,
	NCHARS is big enough. Added a fflush to casetm, so .fm <file>
	will be up to date.

June 25, 1993 (Rich):

    -t option

	reinstated for the sake of compatibility. Some old
	shells scripts and man(1) from SunOs want this, sigh

    Compiler and system dependencies

	Some systems pull in sys/types.h via #include <time.h> and then
	the compiler complains about two ushort typedefs. Therefore,
	ushort is now Ushort (and uchar Uchar).

	The SVID specifies a strdup, POSIX doesn't, anyway, troff
	provides its own version, slightly different then the standard
	one. A To prevent name clashes with that definion, renamed to
	strdupl.

June 24, 1993 (Rich):

	-V option added for DWB3.4 (rich)

May 18, 1993:

    Trivial fix (.cf) request for troff -a 

	issuing

		.cf /dev/null

	with troff -a gives some spurious output:

		H720
		H720
		s10
		f1

	fixed  by checking for ascii mode it ptesc(), ptps() and
	ptfont() in t10.c


    Enhancement

	Added a .tm request to roff. Works just like .tm, but now
	it will do it to file. The name is coined by Carmela. Great
	for creating indeces & toc's (we hope).

May 18 1993:

    Compatibilty change

	Somebody complained that his favorite macro didn't work:
	it had a BELL (^G) in the name.  This was a non-documented
	feature of earlier versions of troff (although the
	documentation actually doesn't say that you can. (They can
	only be used for delimiters or with the tr request), so it
	isn't that important).

	But the sake of eternal backward compatibilaty I allowed
	some control characters like, STX, ACK,  etc. also be part
	of a macro/string name.

	While at it, I made it also possible to have eight bit
	characters be part of the name. It might be that this screws
	up the way users think about these things. For UNICODE
	versions, they probably want to do that as well, and that
	won't work as easy, (because these characters are 16-bits
	wide), so it is dubious whether we actually want this.

	BTW. Now

		.de \(ts\ts
		.tm terminal sigma macro
		..
		.\(ts\(ts

	also works, as long the internal cookie for ts isn't more then
	eight bits.

May 12, 1993:

    Syntax change

	Some requests accept tabs as a separator, some don't and
	this can be a nuisance.  Now a tab is also recognized as
	an argument separator for requests, this makes

		.so	/dev/null

	works.

	To be more precise, any motion character is allowed, so

		.so\h'5i'/dev/null

	will work as well, if one really wants that.

	It will be a problem for users who really relied on this as in

		.ds x	string
	
	and expect the tab to become part of the string a, but I haven't
	seen any use of that (obscure trick).

May 6, 1993:

    Eileen count fixed

	Troff sometimes went in a loop, and exited with: ``job
	looping; check abuse of macros'' (also known as the Eileen's
	loop). It can be forced with the next trivial programme:

		.de ff
		.di xx
		..
		.wh -1 ff
		.bp

	Basically what happens is that a page transition now will
	happen in a diversion, which doesn't make sense. Wat really
	happens is that eject() (in n7.c) doesn't eject the frame
	because we are in a diversion.  This cause the loop in n1.c
	(because now always stack->pname <= ejl). Adding check on
	whether we are not in a diversion takes care of the problem.

March 30, 1993:

    Need request, .ne

	When there is a begin of page trap set, and the first thing
	in the file is a .ne request, the trap gets fired, but,
	the x font R etc. cookies doen't come out, because the
	troff thinks that the first page pseudo transition already
	took place.  Fixed by forcing the start of the first page
	in the casene request with the same code as in casetl (which
	caused a similar problem quite some time ago).

    Change to .cf request ``Here document''

	If the argument of .cf starts with a <<, the rest of it is taken
	as an EOF token. It will reat the rest of the input until it hits
	the EOF token and copies it to the output. This is similar as
	the shell's ``here document'' mechanisme and put in place to
	improve the kludgy way picasso, picpack etc. now include
	postscript.

    Using troff -TLatin1 (DWB version) and \N'...' caused core dump

	In t11, in chadd, it should test on NCHARS - ALPHABET to see
	whether we run out of table space (and we probably should beaf
	up NCHARS for the DWB version).

March 16, 1993:

    Diversion rename bug fix

	It is possible to get troff in an infinite loop by renaming a
	diversion in progress, and calling it later with the
	new name (as in .di xx, .rn xx yy, .yy). The effect depends on
	whether troff already put stuff in the diversion or not.

	Fix by having .rn also rename the current diversion (if
	there is any and when appropriate).  If the diversion calls
	itself by the new name and given the fix made on 11 nov
	1992, this will now result in an error.  (BTW, the fix from
	11 nov is improved: diversions nest, so we have to account
	for that).

December 18, 1992: