fixes

著名Awk语言的编译器

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This file lists all bug fixes, changes, etc., made since the AWK book
was sent to the printers in August, 1987.

Nov 22, 2003:
	fixed a bug in regular expressions that dates (so help me) from 1977;
	it's been there from the beginning.  an anchored longest match that
	was longer than the number of states triggered a failure to initialize
	the machine properly.  many thanks to moinak ghosh for not only finding
	this one but for providing a fix, in some of the most mysterious
	code known to man.

	fixed a storage leak in call() that appears to have been there since
	1983 or so -- a function without an explicit return that assigns a 
	string to a parameter leaked a Cell.  thanks to moinak ghosh for 
	spotting this very subtle one.

Jul 31, 2003:
	fixed, thanks to andrey chernov and ruslan ermilov, a bug in lex.c
	that mis-handled the character 255 in input.  (it was being compared
	to EOF with a signed comparison.)

Jul 29, 2003:
	fixed (i think) the long-standing botch that included the beginning of
	line state ^ for RE's in the set of valid characters; this led to a
	variety of odd problems, including failure to properly match certain
	regular expressions in non-US locales.  thanks to ruslan for keeping
	at this one.

Jul 28, 2003:
	n-th try at getting internationalization right, with thanks to volker
	kiefel, arnold robbins and ruslan ermilov for advice, though they
	should not be blamed for the outcome.  according to posix, "."  is the
	radix character in programs and command line arguments regardless of
	the locale; otherwise, the locale should prevail for input and output
	of numbers.  so it's intended to work that way.
	
	i have rescinded the attempt to use strcoll in expanding shorthands in
	regular expressions (cclenter).  its properties are much too
	surprising; for example [a-c] matches aAbBc in locale en_US but abBcC
	in locale fr_CA.  i can see how this might arise by implementation
	but i cannot explain it to a human user.  (this behavior can be seen
	in gawk as well; we're leaning on the same library.)

	the issue appears to be that strcoll is meant for sorting, where
	merging upper and lower case may make sense (though note that unix
	sort does not do this by default either).  it is not appropriate
	for regular expressions, where the goal is to match specific
	patterns of characters.  in any case, the notations [:lower:], etc.,
	are available in awk, and they are more likely to work correctly in
	most locales.

	a moratorium is hereby declared on internationalization changes.
	i apologize to friends and colleagues in other parts of the world.
	i would truly like to get this "right", but i don't know what
	that is, and i do not want to keep making changes until it's clear.

Jul 4, 2003:
	fixed bug that permitted non-terminated RE, as in "awk /x".

Jun 1, 2003:
	subtle change to split: if source is empty, number of elems
	is always 0 and the array is not set.

Mar 21, 2003:
	added some parens to isblank, in another attempt to make things
	internationally portable.

Mar 14, 2003:
	the internationalization changes, somewhat modified, are now
	reinstated.  in theory awk will now do character comparisons
	and case conversions in national language, but "." will always
	be the decimal point separator on input and output regardless
	of national language.  isblank(){} has an #ifndef.

	this no longer compiles on windows: LC_MESSAGES isn't defined
	in vc6++.

	fixed subtle behavior in field and record splitting: if FS is
	a single character and RS is not empty, \n is NOT a separator.
	this tortuous reading is found in the awk book; behavior now
	matches gawk and mawk.

Dec 13, 2002:
	for the moment, the internationalization changes of nov 29 are
	rolled back -- programs like x = 1.2 don't work in some locales,
	because the parser is expecting x = 1,2.  until i understand this
	better, this will have to wait.

Nov 29, 2002:
	modified b.c (with tiny changes in main and run) to support
	locales, using strcoll and iswhatever tests for posix character
	classes.  thanks to ruslan ermilov ([e-mail]) for code.
	the function isblank doesn't seem to have propagated to any
	header file near me, so it's there explicitly.  not properly
	tested on non-ascii character sets by me.

Jun 28, 2002:
	modified run/format() and tran/getsval() to do a slightly better
	job on using OFMT for output from print and CONVFMT for other
	number->string conversions, as promised by posix and done by 
	gawk and mawk.  there are still places where it doesn't work
	right if CONVFMT is changed; by then the STR attribute of the
	variable has been irrevocably set.  thanks to arnold robbins for
	code and examples.

	fixed subtle bug in format that could get core dump.  thanks to
	Jaromir Dolecek <[e-mail]> for finding and fixing.
	minor cleanup in run.c / format() at the same time.

	added some tests for null pointers to debugging printf's, which
	were never intended for external consumption.  thanks to dave
	kerns ([e-mail]) for pointing this out.

	GNU compatibility: an empty regexp matches anything (thanks to
	dag-erling smorgrav, [e-mail]).  subject to reversion if
	this does more harm than good.

	pervasive small changes to make things more const-correct, as
	reported by gcc's -Wwrite-strings.  as it says in the gcc manual,
	this may be more nuisance than useful.  provoked by a suggestion
	and code from arnaud desitter, [e-mail]

	minor documentation changes to note that this now compiles out
	of the box on Mac OS X.

Feb 10, 2002:
	changed types in posix chars structure to quiet solaris cc.

Jan 1, 2002:
	fflush() or fflush("") flushes all files and pipes.

	length(arrayname) returns number of elements; thanks to 
	arnold robbins for suggestion.

	added a makefile.win to make it easier to build on windows.
	based on dan allen's buildwin.bat.

Nov 16, 2001:
	added support for posix character class names like [:digit:],
	which are not exactly shorter than [0-9] and perhaps no more
	portable.  thanks to dag-erling smorgrav for code.

Feb 16, 2001:
	removed -m option; no longer needed, and it was actually
	broken (noted thanks to volker kiefel).

Feb 10, 2001:
	fixed an appalling bug in gettok: any sequence of digits, +,-, E, e,
	and period was accepted as a valid number if it started with a period.
	this would never have happened with the lex version.

	other 1-character botches, now fixed, include a bare $ and a
	bare " at the end of the input.

Feb 7, 2001:
	more (const char *) casts in b.c and tran.c to silence warnings.

Nov 15, 2000:
	fixed a bug introduced in august 1997 that caused expressions
	like $f[1] to be syntax errors.  thanks to arnold robbins for
	noticing this and providing a fix.

Oct 30, 2000:
	fixed some nextfile bugs: not handling all cases.  thanks to
	arnold robbins for pointing this out.  new regressions added.

	close() is now a function.  it returns whatever the library
	fclose returns, and -1 for closing a file or pipe that wasn't
	opened.

Sep 24, 2000:
	permit \n explicitly in character classes; won't work right
	if comes in as "[\n]" but ok as /[\n]/, because of multiple
	processing of \'s.  thanks to arnold robbins.

July 5, 2000:
	minor fiddles in tran.c to keep compilers happy about uschar.
	thanks to norman wilson.

May 25, 2000:
	yet another attempt at making 8-bit input work, with another
	band-aid in b.c (member()), and some (uschar) casts to head 
	off potential errors in subscripts (like isdigit).  also
	changed HAT to NCHARS-2.  thanks again to santiago vila.

	changed maketab.c to ignore apparently out of range definitions
	instead of halting; new freeBSD generates one.  thanks to
	jon snader <[e-mail]> for pointing out the problem.

May 2, 2000:
	fixed an 8-bit problem in b.c by making several char*'s into
	unsigned char*'s.  not clear i have them all yet.  thanks to
	Santiago Vila <[e-mail]> for the bug report.

Apr 21, 2000:
	finally found and fixed a memory leak in function call; it's
	been there since functions were added ~1983.  thanks to
	jon bentley for the test case that found it.

	added test in envinit to catch environment "variables" with
	names begining with '='; thanks to Berend Hasselman.

Jul 28, 1999:
	added test in defn() to catch function foo(foo), which
	otherwise recurses until core dump.  thanks to arnold
	robbins for noticing this.

Jun 20, 1999:
	added *bp in gettok in lex.c; appears possible to exit function
	without terminating the string.  thanks to russ cox.

Jun 2, 1999:
	added function stdinit() to run to initialize files[] array,
	in case stdin, etc., are not constants; some compilers care.

May 10, 1999:
	replaced the ERROR ... FATAL, etc., macros with functions
	based on vprintf, to avoid problems caused by overrunning
	fixed-size errbuf array.  thanks to ralph corderoy for the
	impetus, and for pointing out a string termination bug in
	qstring as well.

Apr 21, 1999:
	fixed bug that caused occasional core dumps with commandline
	variable with value ending in \.  (thanks to nelson beebe for
	the test case.)

Apr 16, 1999:
	with code kindly provided by Bruce Lilly, awk now parses 
	/=/ and similar constructs more sensibly in more places.
	Bruce also provided some helpful test cases.

Apr 5, 1999:
	changed true/false to True/False in run.c to make it
	easier to compile with C++.  Added some casts on malloc
	and realloc to be honest about casts; ditto.  changed
	ltype int to long in struct rrow to reduce some 64-bit
	complaints; other changes scattered throughout for the
	same purpose.  thanks to Nelson Beebe for these portability
	improvements.

	removed some horrible pointer-int casting in b.c and elsewhere
	by adding ptoi and itonp to localize the casts, which are
	all benign.  fixed one incipient bug that showed up on sgi
	in 64-bit mode.

	reset lineno for new source file; include filename in error
	message.  also fixed line number error in continuation lines.
	(thanks to Nelson Beebe for both of these.)

Mar 24, 1999:
	Nelson Beebe notes that irix 5.3 yacc dies with a bogus
	error; use a newer version or switch to bison, since sgi
	is unlikely to fix it.

Mar 5, 1999:
	changed isnumber to is_number to avoid the problem caused by
	versions of ctype.h that include the name isnumber.

	distribution now includes a script for building on a Mac,
	thanks to Dan Allen.

Feb 20, 1999:
	fixed memory leaks in run.c (call) and tran.c (setfval).
	thanks to Stephen Nutt for finding these and providing the fixes.

Jan 13, 1999:
	replaced srand argument by (unsigned int) in run.c;
	avoids problem on Mac and potentially on Unix & Windows.
	thanks to Dan Allen.

	added a few (int) casts to silence useless compiler warnings.
	e.g., errorflag= in run.c jump().

	added proctab.c to the bundle outout; one less thing
	to have to compile out of the box.

	added calls to _popen and _pclose to the win95 stub for
	pipes (thanks to Steve Adams for this helpful suggestion).
	seems to work, though properties are not well understood
	by me, and it appears that under some circumstances the
	pipe output is truncated.  Be careful.

Oct 19, 1998:
	fixed a couple of bugs in getrec: could fail to update $0
	after a getline var; because inputFS wasn't initialized, 
	could split $0 on every character, a misleading diversion.

	fixed caching bug in makedfa: LRU was actually removing
	least often used.

	thanks to ross ridge for finding these, and for providing
	great bug reports.

May 12, 1998:
	fixed potential bug in readrec: might fail to update record
	pointer after growing.  thanks to dan levy for spotting this
	and suggesting the fix.

Mar 12, 1998:
	added -V to print version number and die.

Feb 11, 1998:
	subtle silent bug in lex.c: if the program ended with a number
	longer than 1 digit, part of the input would be pushed back and
	parsed again because token buffer wasn't terminated right.
	example:  awk 'length($0) > 10'.  blush.  at least i found it
	myself.

Aug 31, 1997:
	s/adelete/awkdelete/: SGI uses this in malloc.h.
	thanks to nelson beebe for pointing this one out.

Aug 21, 1997:
	fixed some bugs in sub and gsub when replacement includes \\.
	this is a dark, horrible corner, but at least now i believe that
	the behavior is the same as gawk and the intended posix standard.
	thanks to arnold robbins for advice here.

Aug 9, 1997:
	somewhat regretfully, replaced the ancient lex-based lexical
	analyzer with one written in C.  it's longer, generates less code,
	and more portable; the old one depended too much on mysterious
	properties of lex that were not preserved in other environments.
	in theory these recognize the same language.

	now using strtod to test whether a string is a number, instead of
	the convoluted original function.  should be more portable and
	reliable if strtod is implemented right.

	removed now-pointless optimization in makefile that tries to avoid
	recompilation when awkgram.y is changed but symbols are not.

	removed most fixed-size arrays, though a handful remain, some
	of which are unchecked.  you have been warned.

Aug 4, 1997:
	with some trepidation, replaced the ancient code that managed
	fields and $0 in fixed-size arrays with arrays that grow on
	demand.  there is still some tension between trying to make this
	run fast and making it clean; not sure it's right yet.

	the ill-conceived -mr and -mf arguments are now useful only
	for debugging.  previous dynamic string code removed.

	numerous other minor cleanups along the way.

Jul 30, 1997:
	using code provided by dan levy (to whom profuse thanks), replaced
	fixed-size arrays and awkward kludges by a fairly uniform mechanism
	to grow arrays as needed for printf, sub, gsub, etc.

Jul 23, 1997:
	falling off the end of a function returns "" and 0, not 0.
	thanks to arnold robbins.

Jun 17, 1997:
	replaced several fixed-size arrays by dynamically-created ones
	in run.c; added overflow tests to some previously unchecked cases.
	getline, toupper, tolower.

	getline code is still broken in that recursive calls may wind
	up using the same space.  [fixed later]

	increased RECSIZE to 8192 to push problems further over the horizon.

	added \r to \n as input line separator for programs, not data.
	damn CRLFs.

	modified format() to permit explicit printf("%c", 0) to include
	a null byte in output.  thanks to ken stailey for the fix.

	added a "-safe" argument that disables file output (print >,
	print >>), process creation (cmd|getline, print |, system), and
	access to the environment (ENVIRON).  this is a first approximation
	to a "safe" version of awk, but don't rely on it too much.  thanks
	to joan feigenbaum and matt blaze for the inspiration long ago.

Jul 8, 1996:
	fixed long-standing bug in sub, gsub(/a/, "\\\\&"); thanks to
	ralph corderoy.

Jun 29, 1996:
	fixed awful bug in new field splitting; didn't get all the places
	where input was done.

Jun 28, 1996:
	changed field-splitting to conform to posix definition: fields are
	split using the value of FS at the time of input; it used to be
	the value when the field or NF was first referred to, a much less
	predictable definition.  thanks to arnold robbins for encouragement
	to do the right thing.

May 28, 1996:
	fixed appalling but apparently unimportant bug in parsing octal
	numbers in reg exprs.

	explicit hex in reg exprs now limited to 2 chars: \xa, \xaa.

May 27, 1996:
	cleaned up some declarations so gcc -Wall is now almost silent.

	makefile now includes backup copies of ytab.c and lexyy.c in case
	one makes before looking; it also avoids recreating lexyy.c unless
	really needed.