Add 'contrib/unifdef/' from commit '0da44885831dc0a43c4ca6ff04a2430993cc0a80'

git-subtree-dir: contrib/unifdef
git-subtree-mainline: 3b7ffacdee49f90716cba2bcf8af3fc1971ae031
git-subtree-split: 0da44885831dc0a43c4ca6ff04a2430993cc0a80

1 files changed, 1675 insertions, 0 deletions

diff --git a/contrib/unifdef/unifdef.c b/contrib/unifdef/unifdef.c
new file mode 100644
index 000000000000..dc145a24232f
--- /dev/null
+++ b/contrib/unifdef/unifdef.c
@@ -0,0 +1,1675 @@
+/*
+ * Copyright (c) 2002 - 2020 Tony Finch <dot@dotat.at>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * unifdef - remove ifdef'ed lines
+ *
+ * This code was derived from software contributed to Berkeley by Dave Yost.
+ * It was rewritten to support ANSI C by Tony Finch. The original version
+ * of unifdef carried the 4-clause BSD copyright licence. None of its code
+ * remains in this version (though some of the names remain) so it now
+ * carries a more liberal licence.
+ *
+ *  Wishlist:
+ *      provide an option which will append the name of the
+ *        appropriate symbol after #else's and #endif's
+ *      provide an option which will check symbols after
+ *        #else's and #endif's to see that they match their
+ *        corresponding #ifdef or #ifndef
+ *
+ *   These require better buffer handling, which would also make
+ *   it possible to handle all "dodgy" directives correctly.
+ */
+
+#include "unifdef.h"
+
+static const char copyright[] =
+    #include "version.h"
+    "@(#) $Author: Tony Finch (dot@dotat.at) $\n"
+    "@(#) $URL: http://dotat.at/prog/unifdef $\n"
+;
+
+/* types of input lines: */
+typedef enum {
+	LT_TRUEI,		/* a true #if with ignore flag */
+	LT_FALSEI,		/* a false #if with ignore flag */
+	LT_IF,			/* an unknown #if */
+	LT_TRUE,		/* a true #if */
+	LT_FALSE,		/* a false #if */
+	LT_ELIF,		/* an unknown #elif */
+	LT_ELTRUE,		/* a true #elif */
+	LT_ELFALSE,		/* a false #elif */
+	LT_ELSE,		/* #else */
+	LT_ENDIF,		/* #endif */
+	LT_DODGY,		/* flag: directive is not on one line */
+	LT_DODGY_LAST = LT_DODGY + LT_ENDIF,
+	LT_PLAIN,		/* ordinary line */
+	LT_EOF,			/* end of file */
+	LT_ERROR,		/* unevaluable #if */
+	LT_COUNT
+} Linetype;
+
+static char const * const linetype_name[] = {
+	"TRUEI", "FALSEI", "IF", "TRUE", "FALSE",
+	"ELIF", "ELTRUE", "ELFALSE", "ELSE", "ENDIF",
+	"DODGY TRUEI", "DODGY FALSEI",
+	"DODGY IF", "DODGY TRUE", "DODGY FALSE",
+	"DODGY ELIF", "DODGY ELTRUE", "DODGY ELFALSE",
+	"DODGY ELSE", "DODGY ENDIF",
+	"PLAIN", "EOF", "ERROR"
+};
+
+#define linetype_if2elif(lt) ((Linetype)(lt - LT_IF + LT_ELIF))
+#define linetype_2dodgy(lt) ((Linetype)(lt + LT_DODGY))
+
+/* state of #if processing */
+typedef enum {
+	IS_OUTSIDE,
+	IS_FALSE_PREFIX,	/* false #if followed by false #elifs */
+	IS_TRUE_PREFIX,		/* first non-false #(el)if is true */
+	IS_PASS_MIDDLE,		/* first non-false #(el)if is unknown */
+	IS_FALSE_MIDDLE,	/* a false #elif after a pass state */
+	IS_TRUE_MIDDLE,		/* a true #elif after a pass state */
+	IS_PASS_ELSE,		/* an else after a pass state */
+	IS_FALSE_ELSE,		/* an else after a true state */
+	IS_TRUE_ELSE,		/* an else after only false states */
+	IS_FALSE_TRAILER,	/* #elifs after a true are false */
+	IS_COUNT
+} Ifstate;
+
+static char const * const ifstate_name[] = {
+	"OUTSIDE", "FALSE_PREFIX", "TRUE_PREFIX",
+	"PASS_MIDDLE", "FALSE_MIDDLE", "TRUE_MIDDLE",
+	"PASS_ELSE", "FALSE_ELSE", "TRUE_ELSE",
+	"FALSE_TRAILER"
+};
+
+/* state of comment parser */
+typedef enum {
+	NO_COMMENT = false,	/* outside a comment */
+	C_COMMENT,		/* in a comment like this one */
+	CXX_COMMENT,		/* between // and end of line */
+	STARTING_COMMENT,	/* just after slash-backslash-newline */
+	FINISHING_COMMENT,	/* star-backslash-newline in a C comment */
+	CHAR_LITERAL,		/* inside '' */
+	STRING_LITERAL,		/* inside "" */
+	RAW_STRING_LITERAL	/* inside R"()" */
+} Comment_state;
+
+static char const * const comment_name[] = {
+	"NO", "C", "CXX", "STARTING", "FINISHING", "CHAR", "STRING"
+};
+
+/* state of preprocessor line parser */
+typedef enum {
+	LS_START,		/* only space and comments on this line */
+	LS_HASH,		/* only space, comments, and a hash */
+	LS_DIRTY		/* this line can't be a preprocessor line */
+} Line_state;
+
+static char const * const linestate_name[] = {
+	"START", "HASH", "DIRTY"
+};
+
+/*
+ * Minimum translation limits from ISO/IEC 9899:1999 5.2.4.1
+ */
+#define	MAXDEPTH        64			/* maximum #if nesting */
+#define	MAXLINE         4096			/* maximum length of line */
+#define	MAXSYMS         16384			/* maximum number of symbols */
+
+/*
+ * Sometimes when editing a keyword the replacement text is longer, so
+ * we leave some space at the end of the tline buffer to accommodate this.
+ */
+#define	EDITSLOP        10
+
+/*
+ * Globals.
+ */
+
+static bool             compblank;		/* -B: compress blank lines */
+static bool             lnblank;		/* -b: blank deleted lines */
+static bool             complement;		/* -c: do the complement */
+static bool             debugging;		/* -d: debugging reports */
+static bool             inplace;		/* -m: modify in place */
+static bool             iocccok;		/* -e: fewer IOCCC errors */
+static bool             strictlogic;		/* -K: keep ambiguous #ifs */
+static bool             killconsts;		/* -k: eval constant #ifs */
+static bool             lnnum;			/* -n: add #line directives */
+static bool             symlist;		/* -s: output symbol list */
+static bool             symdepth;		/* -S: output symbol depth */
+static bool             text;			/* -t: this is a text file */
+
+static const char      *symname[MAXSYMS];	/* symbol name */
+static const char      *value[MAXSYMS];		/* -Dsym=value */
+static bool             ignore[MAXSYMS];	/* -iDsym or -iUsym */
+static int              nsyms;			/* number of symbols */
+
+static FILE            *input;			/* input file pointer */
+static const char      *filename;		/* input file name */
+static int              linenum;		/* current line number */
+static const char      *linefile;		/* file name for #line */
+static FILE            *output;			/* output file pointer */
+static const char      *ofilename;		/* output file name */
+static const char      *backext;		/* backup extension */
+static char            *tempname;		/* avoid splatting input */
+
+static char             tline[MAXLINE+EDITSLOP];/* input buffer plus space */
+static char            *keyword;		/* used for editing #elif's */
+
+/*
+ * When processing a file, the output's newline style will match the
+ * input's, and unifdef correctly handles CRLF or LF endings whatever
+ * the platform's native style. The stdio streams are opened in binary
+ * mode to accommodate platforms whose native newline style is CRLF.
+ * When the output isn't a processed input file (when it is error /
+ * debug / diagnostic messages) then unifdef uses native line endings.
+ */
+
+static const char      *newline;		/* input file format */
+static const char       newline_unix[] = "\n";
+static const char       newline_crlf[] = "\r\n";
+
+static Comment_state    incomment;		/* comment parser state */
+static Line_state       linestate;		/* #if line parser state */
+static Ifstate          ifstate[MAXDEPTH];	/* #if processor state */
+static bool             ignoring[MAXDEPTH];	/* ignore comments state */
+static int              stifline[MAXDEPTH];	/* start of current #if */
+static int              depth;			/* current #if nesting */
+static int              delcount;		/* count of deleted lines */
+static unsigned         blankcount;		/* count of blank lines */
+static unsigned         blankmax;		/* maximum recent blankcount */
+static bool             constexpr;		/* constant #if expression */
+static bool             zerosyms;		/* to format symdepth output */
+static bool             firstsym;		/* ditto */
+
+static int              exitmode;		/* exit status mode */
+static int              exitstat;		/* program exit status */
+static bool             altered;		/* was this file modified? */
+
+static void             addsym1(bool, bool, char *);
+static void             addsym2(bool, const char *, const char *);
+static char            *astrcat(const char *, const char *);
+static void             cleantemp(void);
+static void             closeio(void);
+static void             debug(const char *, ...);
+static void             debugsym(const char *, int);
+static bool             defundef(void);
+static void             defundefile(const char *);
+static void             done(void);
+static void             error(const char *);
+static int              findsym(const char **);
+static void             flushline(bool);
+static void             hashline(void);
+static void             help(void);
+static Linetype         ifeval(const char **);
+static void             ignoreoff(void);
+static void             ignoreon(void);
+static void             indirectsym(void);
+static void             keywordedit(const char *);
+static const char      *matchsym(const char *, const char *);
+static void             nest(void);
+static Linetype         parseline(void);
+static void             process(void);
+static void             processinout(const char *, const char *);
+static const char      *skipargs(const char *);
+static const char      *skipcomment(const char *);
+static const char      *skiphash(void);
+static const char      *skipline(const char *);
+static const char      *skipsym(const char *);
+static void             state(Ifstate);
+static void             unnest(void);
+static void             usage(void);
+static void             version(void);
+static const char      *xstrdup(const char *, const char *);
+
+#define endsym(c) (!isalnum((unsigned char)c) && c != '_')
+
+/*
+ * The main program.
+ */
+int
+main(int argc, char *argv[])
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "i:D:U:f:I:M:o:x:bBcdehKklmnsStV")) != -1)
+		switch (opt) {
+		case 'i': /* treat stuff controlled by these symbols as text */
+			/*
+			 * For strict backwards-compatibility the U or D
+			 * should be immediately after the -i but it doesn't
+			 * matter much if we relax that requirement.
+			 */
+			opt = *optarg++;
+			if (opt == 'D')
+				addsym1(true, true, optarg);
+			else if (opt == 'U')
+				addsym1(true, false, optarg);
+			else
+				usage();
+			break;
+		case 'D': /* define a symbol */
+			addsym1(false, true, optarg);
+			break;
+		case 'U': /* undef a symbol */
+			addsym1(false, false, optarg);
+			break;
+		case 'I': /* no-op for compatibility with cpp */
+			break;
+		case 'b': /* blank deleted lines instead of omitting them */
+		case 'l': /* backwards compatibility */
+			lnblank = true;
+			break;
+		case 'B': /* compress blank lines around removed section */
+			compblank = true;
+			break;
+		case 'c': /* treat -D as -U and vice versa */
+			complement = true;
+			break;
+		case 'd':
+			debugging = true;
+			break;
+		case 'e': /* fewer errors from dodgy lines */
+			iocccok = true;
+			break;
+		case 'f': /* definitions file */
+			defundefile(optarg);
+			break;
+		case 'h':
+			help();
+			break;
+		case 'K': /* keep ambiguous #ifs */
+			strictlogic = true;
+			break;
+		case 'k': /* process constant #ifs */
+			killconsts = true;
+			break;
+		case 'm': /* modify in place */
+			inplace = true;
+			break;
+		case 'M': /* modify in place and keep backup */
+			inplace = true;
+			if (strlen(optarg) > 0)
+				backext = optarg;
+			break;
+		case 'n': /* add #line directive after deleted lines */
+			lnnum = true;
+			break;
+		case 'o': /* output to a file */
+			ofilename = optarg;
+			break;
+		case 's': /* only output list of symbols that control #ifs */
+			symlist = true;
+			break;
+		case 'S': /* list symbols with their nesting depth */
+			symlist = symdepth = true;
+			break;
+		case 't': /* don't parse C comments */
+			text = true;
+			break;
+		case 'V':
+			version();
+			break;
+		case 'x':
+			exitmode = atoi(optarg);
+			if(exitmode < 0 || exitmode > 2)
+				usage();
+			break;
+		default:
+			usage();
+		}
+	argc -= optind;
+	argv += optind;
+	if (compblank && lnblank)
+		errx(2, "-B and -b are mutually exclusive");
+	if (symlist && (ofilename != NULL || inplace || argc > 1))
+		errx(2, "-s only works with one input file");
+	if (argc > 1 && ofilename != NULL)
+		errx(2, "-o cannot be used with multiple input files");
+	if (argc > 1 && !inplace)
+		errx(2, "multiple input files require -m or -M");
+	if (argc == 0 && inplace)
+		errx(2, "-m requires an input file");
+	if (argc == 0)
+		argc = 1;
+	if (argc == 1 && !inplace && ofilename == NULL)
+		ofilename = "-";
+	indirectsym();
+
+	atexit(cleantemp);
+	if (ofilename != NULL)
+		processinout(*argv, ofilename);
+	else while (argc-- > 0) {
+		processinout(*argv, *argv);
+		argv++;
+	}
+	switch(exitmode) {
+	case(0): exit(exitstat);
+	case(1): exit(!exitstat);
+	case(2): exit(0);
+	default: abort(); /* bug */
+	}
+}
+
+/*
+ * File logistics.
+ */
+static void
+processinout(const char *ifn, const char *ofn)
+{
+	struct stat st;
+
+	if (ifn == NULL || strcmp(ifn, "-") == 0) {
+		filename = "[stdin]";
+		linefile = NULL;
+		input = fbinmode(stdin);
+	} else {
+		filename = ifn;
+		linefile = ifn;
+		input = fopen(ifn, "rb");
+		if (input == NULL)
+			err(2, "can't open %s", ifn);
+	}
+	if (strcmp(ofn, "-") == 0) {
+		output = fbinmode(stdout);
+		process();
+		return;
+	}
+	if (stat(ofn, &st) < 0) {
+		output = fopen(ofn, "wb");
+		if (output == NULL)
+			err(2, "can't create %s", ofn);
+		process();
+		return;
+	}
+
+	tempname = astrcat(ofn, ".XXXXXX");
+	output = mktempmode(tempname, st.st_mode);
+	if (output == NULL)
+		err(2, "can't create %s", tempname);
+
+	process();
+
+	if (backext != NULL) {
+		char *backname = astrcat(ofn, backext);
+		if (rename(ofn, backname) < 0)
+			err(2, "can't rename \"%s\" to \"%s\"", ofn, backname);
+		free(backname);
+	}
+	/* leave file unmodified if unifdef made no changes */
+	if (!altered && backext == NULL) {
+		if (remove(tempname) < 0)
+			warn("can't remove \"%s\"", tempname);
+	} else if (replace(tempname, ofn) < 0)
+		err(2, "can't rename \"%s\" to \"%s\"", tempname, ofn);
+	free(tempname);
+	tempname = NULL;
+}
+
+/*
+ * For cleaning up if there is an error.
+ */
+static void
+cleantemp(void)
+{
+	if (tempname != NULL)
+		remove(tempname);
+}
+
+/*
+ * Self-identification functions.
+ */
+
+static void
+version(void)
+{
+	const char *c = copyright;
+	for (;;) {
+		while (*++c != '$')
+			if (*c == '\0')
+				exit(0);
+		while (*++c != '$')
+			putc(*c, stderr);
+		putc('\n', stderr);
+	}
+}
+
+static void
+synopsis(FILE *fp)
+{
+	fprintf(fp,
+	    "usage:	unifdef [-bBcdehKkmnsStV] [-x{012}] [-Mext] [-opath] \\\n"
+	    "		[-[i]Dsym[=val]] [-[i]Usym] [-fpath] ... [file] ...\n");
+}
+
+static void
+usage(void)
+{
+	synopsis(stderr);
+	exit(2);
+}
+
+static void
+help(void)
+{
+	synopsis(stdout);
+	printf(
+	    "	-Dsym=val  define preprocessor symbol with given value\n"
+	    "	-Dsym      define preprocessor symbol with value 1\n"
+	    "	-Usym	   preprocessor symbol is undefined\n"
+	    "	-iDsym=val \\  ignore C strings and comments\n"
+	    "	-iDsym      ) in sections controlled by these\n"
+	    "	-iUsym	   /  preprocessor symbols\n"
+	    "	-fpath	file containing #define and #undef directives\n"
+	    "	-b	blank lines instead of deleting them\n"
+	    "	-B	compress blank lines around deleted section\n"
+	    "	-c	complement (invert) keep vs. delete\n"
+	    "	-d	debugging mode\n"
+	    "	-e	ignore multiline preprocessor directives\n"
+	    "	-h	print help\n"
+	    "	-Ipath	extra include file path (ignored)\n"
+	    "	-K	disable && and || short-circuiting\n"
+	    "	-k	process constant #if expressions\n"
+	    "	-Mext	modify in place and keep backups\n"
+	    "	-m	modify input files in place\n"
+	    "	-n	add #line directives to output\n"
+	    "	-opath	output file name\n"
+	    "	-S	list #if control symbols with nesting\n"
+	    "	-s	list #if control symbols\n"
+	    "	-t	ignore C strings and comments\n"
+	    "	-V	print version\n"
+	    "	-x{012}	exit status mode\n"
+	);
+	exit(0);
+}
+
+/*
+ * A state transition function alters the global #if processing state
+ * in a particular way. The table below is indexed by the current
+ * processing state and the type of the current line.
+ *
+ * Nesting is handled by keeping a stack of states; some transition
+ * functions increase or decrease the depth. They also maintain the
+ * ignore state on a stack. In some complicated cases they have to
+ * alter the preprocessor directive, as follows.
+ *
+ * When we have processed a group that starts off with a known-false
+ * #if/#elif sequence (which has therefore been deleted) followed by a
+ * #elif that we don't understand and therefore must keep, we edit the
+ * latter into a #if to keep the nesting correct. We use memcpy() to
+ * overwrite the 4 byte token "elif" with "if  " without a '\0' byte.
+ *
+ * When we find a true #elif in a group, the following block will
+ * always be kept and the rest of the sequence after the next #elif or
+ * #else will be discarded. We edit the #elif into a #else and the
+ * following directive to #endif since this has the desired behaviour.
+ *
+ * "Dodgy" directives are split across multiple lines, the most common
+ * example being a multi-line comment hanging off the right of the
+ * directive. We can handle them correctly only if there is no change
+ * from printing to dropping (or vice versa) caused by that directive.
+ * If the directive is the first of a group we have a choice between
+ * failing with an error, or passing it through unchanged instead of
+ * evaluating it. The latter is not the default to avoid questions from
+ * users about unifdef unexpectedly leaving behind preprocessor directives.
+ */
+typedef void state_fn(void);
+
+/* report an error */
+static void Eelif (void) { error("Inappropriate #elif"); }
+static void Eelse (void) { error("Inappropriate #else"); }
+static void Eendif(void) { error("Inappropriate #endif"); }
+static void Eeof  (void) { error("Premature EOF"); }
+static void Eioccc(void) { error("Obfuscated preprocessor control line"); }
+/* plain line handling */
+static void print (void) { flushline(true); }
+static void drop  (void) { flushline(false); }
+/* output lacks group's start line */
+static void Strue (void) { drop();  ignoreoff(); state(IS_TRUE_PREFIX); }
+static void Sfalse(void) { drop();  ignoreoff(); state(IS_FALSE_PREFIX); }
+static void Selse (void) { drop();               state(IS_TRUE_ELSE); }
+/* print/pass this block */
+static void Pelif (void) { print(); ignoreoff(); state(IS_PASS_MIDDLE); }
+static void Pelse (void) { print();              state(IS_PASS_ELSE); }
+static void Pendif(void) { print(); unnest(); }
+/* discard this block */
+static void Dfalse(void) { drop();  ignoreoff(); state(IS_FALSE_TRAILER); }
+static void Delif (void) { drop();  ignoreoff(); state(IS_FALSE_MIDDLE); }
+static void Delse (void) { drop();               state(IS_FALSE_ELSE); }
+static void Dendif(void) { drop();  unnest(); }
+/* first line of group */
+static void Fdrop (void) { nest();  Dfalse(); }
+static void Fpass (void) { nest();  Pelif(); }
+static void Ftrue (void) { nest();  Strue(); }
+static void Ffalse(void) { nest();  Sfalse(); }
+/* variable pedantry for obfuscated lines */
+static void Oiffy (void) { if (!iocccok) Eioccc(); Fpass(); ignoreon(); }
+static void Oif   (void) { if (!iocccok) Eioccc(); Fpass(); }
+static void Oelif (void) { if (!iocccok) Eioccc(); Pelif(); }
+/* ignore comments in this block */
+static void Idrop (void) { Fdrop();  ignoreon(); }
+static void Itrue (void) { Ftrue();  ignoreon(); }
+static void Ifalse(void) { Ffalse(); ignoreon(); }
+/* modify this line */
+static void Mpass (void) { memcpy(keyword, "if  ", 4); Pelif(); }
+static void Mtrue (void) { keywordedit("else");  state(IS_TRUE_MIDDLE); }
+static void Melif (void) { keywordedit("endif"); state(IS_FALSE_TRAILER); }
+static void Melse (void) { keywordedit("endif"); state(IS_FALSE_ELSE); }
+
+static state_fn * const trans_table[IS_COUNT][LT_COUNT] = {
+/* IS_OUTSIDE */
+{ Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Eendif,
+  Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Eendif,
+  print, done,  abort },
+/* IS_FALSE_PREFIX */
+{ Idrop, Idrop, Fdrop, Fdrop, Fdrop, Mpass, Strue, Sfalse,Selse, Dendif,
+  Idrop, Idrop, Fdrop, Fdrop, Fdrop, Mpass, Eioccc,Eioccc,Eioccc,Eioccc,
+  drop,  Eeof,  abort },
+/* IS_TRUE_PREFIX */
+{ Itrue, Ifalse,Fpass, Ftrue, Ffalse,Dfalse,Dfalse,Dfalse,Delse, Dendif,
+  Oiffy, Oiffy, Fpass, Oif,   Oif,   Eioccc,Eioccc,Eioccc,Eioccc,Eioccc,
+  print, Eeof,  abort },
+/* IS_PASS_MIDDLE */
+{ Itrue, Ifalse,Fpass, Ftrue, Ffalse,Pelif, Mtrue, Delif, Pelse, Pendif,
+  Oiffy, Oiffy, Fpass, Oif,   Oif,   Pelif, Oelif, Oelif, Pelse, Pendif,
+  print, Eeof,  abort },
+/* IS_FALSE_MIDDLE */
+{ Idrop, Idrop, Fdrop, Fdrop, Fdrop, Pelif, Mtrue, Delif, Pelse, Pendif,
+  Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eioccc,Eioccc,Eioccc,Eioccc,Eioccc,
+  drop,  Eeof,  abort },
+/* IS_TRUE_MIDDLE */
+{ Itrue, Ifalse,Fpass, Ftrue, Ffalse,Melif, Melif, Melif, Melse, Pendif,
+  Oiffy, Oiffy, Fpass, Oif,   Oif,   Eioccc,Eioccc,Eioccc,Eioccc,Pendif,
+  print, Eeof,  abort },
+/* IS_PASS_ELSE */
+{ Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Pendif,
+  Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Pendif,
+  print, Eeof,  abort },
+/* IS_FALSE_ELSE */
+{ Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eelif, Eelif, Eelif, Eelse, Dendif,
+  Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eelif, Eelif, Eelif, Eelse, Eioccc,
+  drop,  Eeof,  abort },
+/* IS_TRUE_ELSE */
+{ Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Dendif,
+  Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Eioccc,
+  print, Eeof,  abort },
+/* IS_FALSE_TRAILER */
+{ Idrop, Idrop, Fdrop, Fdrop, Fdrop, Dfalse,Dfalse,Dfalse,Delse, Dendif,
+  Idrop, Idrop, Fdrop, Fdrop, Fdrop, Dfalse,Dfalse,Dfalse,Delse, Eioccc,
+  drop,  Eeof,  abort }
+/*TRUEI  FALSEI IF     TRUE   FALSE  ELIF   ELTRUE ELFALSE ELSE  ENDIF
+  TRUEI  FALSEI IF     TRUE   FALSE  ELIF   ELTRUE ELFALSE ELSE  ENDIF (DODGY)
+  PLAIN  EOF    ERROR */
+};
+
+/*
+ * State machine utility functions
+ */
+static void
+ignoreoff(void)
+{
+	if (depth == 0)
+		abort(); /* bug */
+	ignoring[depth] = ignoring[depth-1];
+}
+static void
+ignoreon(void)
+{
+	ignoring[depth] = true;
+}
+static void
+keywordedit(const char *replacement)
+{
+	snprintf(keyword, tline + sizeof(tline) - keyword,
+	    "%s%s", replacement, newline);
+	altered = true;
+	print();
+}
+static void
+nest(void)
+{
+	if (depth > MAXDEPTH-1)
+		abort(); /* bug */
+	if (depth == MAXDEPTH-1)
+		error("Too many levels of nesting");
+	depth += 1;
+	stifline[depth] = linenum;
+}
+static void
+unnest(void)
+{
+	if (depth == 0)
+		abort(); /* bug */
+	depth -= 1;
+}
+static void
+state(Ifstate is)
+{
+	ifstate[depth] = is;
+}
+
+/*
+ * The last state transition function. When this is called,
+ * lineval == LT_EOF, so the process() loop will terminate.
+ */
+static void
+done(void)
+{
+	if (incomment)
+		error("EOF in comment");
+	closeio();
+}
+
+/*
+ * Write a line to the output or not, according to command line options.
+ * If writing fails, closeio() will print the error and exit.
+ */
+static void
+flushline(bool keep)
+{
+	if (symlist)
+		return;
+	if (keep ^ complement) {
+		bool blankline = tline[strspn(tline, " \t\r\n")] == '\0';
+		if (blankline && compblank && blankcount != blankmax) {
+			delcount += 1;
+			blankcount += 1;
+		} else {
+			if (lnnum && delcount > 0)
+				hashline();
+			if (fputs(tline, output) == EOF)
+				closeio();
+			delcount = 0;
+			blankmax = blankcount = blankline ? blankcount + 1 : 0;
+		}
+	} else {
+		if (lnblank && fputs(newline, output) == EOF)
+			closeio();
+		altered = true;
+		delcount += 1;
+		blankcount = 0;
+	}
+	if (debugging && fflush(output) == EOF)
+		closeio();
+}
+
+/*
+ * Format of #line directives depends on whether we know the input filename.
+ */
+static void
+hashline(void)
+{
+	int e;
+
+	if (linefile == NULL)
+		e = fprintf(output, "#line %d%s", linenum, newline);
+	else
+		e = fprintf(output, "#line %d \"%s\"%s",
+		    linenum, linefile, newline);
+	if (e < 0)
+		closeio();
+}
+
+/*
+ * Flush the output and handle errors.
+ */
+static void
+closeio(void)
+{
+	/* Tidy up after findsym(). */
+	if (symdepth && !zerosyms)
+		printf("\n");
+	if (output != NULL && (ferror(output) || fclose(output) == EOF))
+			err(2, "%s: can't write to output", filename);
+	fclose(input);
+}
+
+/*
+ * The driver for the state machine.
+ */
+static void
+process(void)
+{
+	Linetype lineval = LT_PLAIN;
+	/* When compressing blank lines, act as if the file
+	   is preceded by a large number of blank lines. */
+	blankmax = blankcount = 1000;
+	zerosyms = true;
+	newline = NULL;
+	linenum = 0;
+	altered = false;
+	while (lineval != LT_EOF) {
+		lineval = parseline();
+		trans_table[ifstate[depth]][lineval]();
+		debug("process line %d %s -> %s depth %d",
+		    linenum, linetype_name[lineval],
+		    ifstate_name[ifstate[depth]], depth);
+	}
+	exitstat |= altered;
+}
+
+/*
+ * Parse a line and determine its type. We keep the preprocessor line
+ * parser state between calls in the global variable linestate, with
+ * help from skipcomment().
+ */
+static Linetype
+parseline(void)
+{
+	const char *cp;
+	int cursym;
+	Linetype retval;
+	Comment_state wascomment;
+
+	wascomment = incomment;
+	cp = skiphash();
+	if (cp == NULL)
+		return (LT_EOF);
+	if (newline == NULL) {
+		if (strrchr(tline, '\n') == strrchr(tline, '\r') + 1)
+			newline = newline_crlf;
+		else
+			newline = newline_unix;
+	}
+	if (*cp == '\0') {
+		retval = LT_PLAIN;
+		goto done;
+	}
+	keyword = tline + (cp - tline);
+	if ((cp = matchsym("ifdef", keyword)) != NULL ||
+	    (cp = matchsym("ifndef", keyword)) != NULL) {
+		cp = skipcomment(cp);
+		if ((cursym = findsym(&cp)) < 0)
+			retval = LT_IF;
+		else {
+			retval = (keyword[2] == 'n')
+			    ? LT_FALSE : LT_TRUE;
+			if (value[cursym] == NULL)
+				retval = (retval == LT_TRUE)
+				    ? LT_FALSE : LT_TRUE;
+			if (ignore[cursym])
+				retval = (retval == LT_TRUE)
+				    ? LT_TRUEI : LT_FALSEI;
+		}
+	} else if ((cp = matchsym("if", keyword)) != NULL)
+		retval = ifeval(&cp);
+	else if ((cp = matchsym("elif", keyword)) != NULL)
+		retval = linetype_if2elif(ifeval(&cp));
+	else if ((cp = matchsym("else", keyword)) != NULL)
+		retval = LT_ELSE;
+	else if ((cp = matchsym("endif", keyword)) != NULL)
+		retval = LT_ENDIF;
+	else {
+		cp = skipsym(keyword);
+		/* no way can we deal with a continuation inside a keyword */
+		if (strncmp(cp, "\\\r\n", 3) == 0 ||
+		    strncmp(cp, "\\\n", 2) == 0)
+			Eioccc();
+		cp = skipline(cp);
+		retval = LT_PLAIN;
+		goto done;
+	}
+	cp = skipcomment(cp);
+	if (*cp != '\0') {
+		cp = skipline(cp);
+		if (retval == LT_TRUE || retval == LT_FALSE ||
+		    retval == LT_TRUEI || retval == LT_FALSEI)
+			retval = LT_IF;
+		if (retval == LT_ELTRUE || retval == LT_ELFALSE)
+			retval = LT_ELIF;
+	}
+	/* the following can happen if the last line of the file lacks a
+	   newline or if there is too much whitespace in a directive */
+	if (linestate == LS_HASH) {
+		long len = cp - tline;
+		if (fgets(tline + len, MAXLINE - len, input) == NULL) {
+			if (ferror(input))
+				err(2, "can't read %s", filename);
+			debug("parser insert newline at EOF", linenum);
+			strcpy(tline + len, newline);
+			cp += strlen(newline);
+			linestate = LS_START;
+		} else {
+			debug("parser concatenate dangling whitespace");
+			++linenum;
+			cp = skipcomment(cp);
+		}
+	}
+	if (retval != LT_PLAIN && (wascomment || linestate != LS_START)) {
+		retval = linetype_2dodgy(retval);
+		linestate = LS_DIRTY;
+	}
+done:
+	debug("parser line %d state %s comment %s line", linenum,
+	    comment_name[incomment], linestate_name[linestate]);
+	return (retval);
+}
+
+/*
+ * These are the binary operators that are supported by the expression
+ * evaluator.
+ */
+static Linetype op_strict(long *p, long v, Linetype at, Linetype bt) {
+	if(at == LT_IF || bt == LT_IF) return (LT_IF);
+	return (*p = v, v ? LT_TRUE : LT_FALSE);
+}
+static Linetype op_lt(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a < b, at, bt);
+}
+static Linetype op_gt(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a > b, at, bt);
+}
+static Linetype op_le(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a <= b, at, bt);
+}
+static Linetype op_ge(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a >= b, at, bt);
+}
+static Linetype op_eq(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a == b, at, bt);
+}
+static Linetype op_ne(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a != b, at, bt);
+}
+static Linetype op_or(long *p, Linetype at, long a, Linetype bt, long b) {
+	if (!strictlogic && (at == LT_TRUE || bt == LT_TRUE))
+		return (*p = 1, LT_TRUE);
+	return op_strict(p, a || b, at, bt);
+}
+static Linetype op_and(long *p, Linetype at, long a, Linetype bt, long b) {
+	if (!strictlogic && (at == LT_FALSE || bt == LT_FALSE))
+		return (*p = 0, LT_FALSE);
+	return op_strict(p, a && b, at, bt);
+}
+static Linetype op_blsh(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a << b, at, bt);
+}
+static Linetype op_brsh(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a >> b, at, bt);
+}
+static Linetype op_add(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a + b, at, bt);
+}
+static Linetype op_sub(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a - b, at, bt);
+}
+static Linetype op_mul(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a * b, at, bt);
+}
+static Linetype op_div(long *p, Linetype at, long a, Linetype bt, long b) {
+	if (bt != LT_TRUE) {
+		debug("eval division by zero");
+		return (LT_ERROR);
+	}
+	return op_strict(p, a / b, at, bt);
+}
+static Linetype op_mod(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a % b, at, bt);
+}
+static Linetype op_bor(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a | b, at, bt);
+}
+static Linetype op_bxor(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a ^ b, at, bt);
+}
+static Linetype op_band(long *p, Linetype at, long a, Linetype bt, long b) {
+	return op_strict(p, a & b, at, bt);
+}
+
+/*
+ * An evaluation function takes three arguments, as follows: (1) a pointer to
+ * an element of the precedence table which lists the operators at the current
+ * level of precedence; (2) a pointer to an integer which will receive the
+ * value of the expression; and (3) a pointer to a char* that points to the
+ * expression to be evaluated and that is updated to the end of the expression
+ * when evaluation is complete. The function returns LT_FALSE if the value of
+ * the expression is zero, LT_TRUE if it is non-zero, LT_IF if the expression
+ * depends on an unknown symbol, or LT_ERROR if there is a parse failure.
+ */
+struct ops;
+
+typedef Linetype eval_fn(const struct ops *, long *, const char **);
+
+static eval_fn eval_table, eval_unary;
+
+/*
+ * The precedence table. Expressions involving binary operators are evaluated
+ * in a table-driven way by eval_table. When it evaluates a subexpression it
+ * calls the inner function with its first argument pointing to the next
+ * element of the table. Innermost expressions have special non-table-driven
+ * handling.
+ *
+ * The stop characters help with lexical analysis: an operator is not
+ * recognized if it is followed by one of the stop characters because
+ * that would make it a different operator.
+ */
+struct op {
+	const char *str;
+	Linetype (*fn)(long *, Linetype, long, Linetype, long);
+	const char *stop;
+};
+struct ops {
+	eval_fn *inner;
+	struct op op[5];
+};
+static const struct ops eval_ops[] = {
+	{ eval_table, { { "||", op_or,   NULL } } },
+	{ eval_table, { { "&&", op_and,  NULL } } },
+	{ eval_table, { { "|",  op_bor,  "|" } } },
+	{ eval_table, { { "^",  op_bxor, NULL } } },
+	{ eval_table, { { "&",  op_band, "&" } } },
+	{ eval_table, { { "==", op_eq,   NULL },
+			{ "!=", op_ne,   NULL } } },
+	{ eval_table, { { "<=", op_le,   NULL },
+			{ ">=", op_ge,   NULL },
+			{ "<",  op_lt,   "<=" },
+			{ ">",  op_gt,   ">=" } } },
+	{ eval_table, { { "<<", op_blsh, NULL },
+			{ ">>", op_brsh, NULL } } },
+	{ eval_table, { { "+",  op_add,  NULL },
+			{ "-",  op_sub,  NULL } } },
+	{ eval_unary, { { "*",  op_mul,  NULL },
+			{ "/",  op_div,  NULL },
+			{ "%",  op_mod,  NULL } } },
+};
+
+/* Current operator precedence level */
+static long prec(const struct ops *ops)
+{
+	return (ops - eval_ops);
+}
+
+/*
+ * Function for evaluating the innermost parts of expressions,
+ * viz. !expr (expr) number defined(symbol) symbol
+ * We reset the constexpr flag in the last two cases.
+ */
+static Linetype
+eval_unary(const struct ops *ops, long *valp, const char **cpp)
+{
+	const char *cp;
+	char *ep;
+	int sym;
+	bool defparen;
+	Linetype lt;
+
+	cp = skipcomment(*cpp);
+	if (*cp == '!') {
+		debug("eval%d !", prec(ops));
+		cp++;
+		lt = eval_unary(ops, valp, &cp);
+		if (lt == LT_ERROR)
+			return (LT_ERROR);
+		if (lt != LT_IF) {
+			*valp = !*valp;
+			lt = *valp ? LT_TRUE : LT_FALSE;
+		}
+	} else if (*cp == '~') {
+		debug("eval%d ~", prec(ops));
+		cp++;
+		lt = eval_unary(ops, valp, &cp);
+		if (lt == LT_ERROR)
+			return (LT_ERROR);
+		if (lt != LT_IF) {
+			*valp = ~(*valp);
+			lt = *valp ? LT_TRUE : LT_FALSE;
+		}
+	} else if (*cp == '-') {
+		debug("eval%d -", prec(ops));
+		cp++;
+		lt = eval_unary(ops, valp, &cp);
+		if (lt == LT_ERROR)
+			return (LT_ERROR);
+		if (lt != LT_IF) {
+			*valp = -(*valp);
+			lt = *valp ? LT_TRUE : LT_FALSE;
+		}
+	} else if (*cp == '(') {
+		cp++;
+		debug("eval%d (", prec(ops));
+		lt = eval_table(eval_ops, valp, &cp);
+		if (lt == LT_ERROR)
+			return (LT_ERROR);
+		cp = skipcomment(cp);
+		if (*cp++ != ')')
+			return (LT_ERROR);
+	} else if (isdigit((unsigned char)*cp)) {
+		debug("eval%d number", prec(ops));
+		*valp = strtol(cp, &ep, 0);
+		if (ep == cp)
+			return (LT_ERROR);
+		lt = *valp ? LT_TRUE : LT_FALSE;
+		cp = ep;
+	} else if (matchsym("defined", cp) != NULL) {
+		cp = skipcomment(cp+7);
+		if (*cp == '(') {
+			cp = skipcomment(cp+1);
+			defparen = true;
+		} else {
+			defparen = false;
+		}
+		sym = findsym(&cp);
+		cp = skipcomment(cp);
+		if (defparen && *cp++ != ')') {
+			debug("eval%d defined missing ')'", prec(ops));
+			return (LT_ERROR);
+		}
+		if (sym < 0) {
+			debug("eval%d defined unknown", prec(ops));
+			lt = LT_IF;
+		} else {
+			debug("eval%d defined %s", prec(ops), symname[sym]);
+			*valp = (value[sym] != NULL);
+			lt = *valp ? LT_TRUE : LT_FALSE;
+		}
+		constexpr = false;
+	} else if (!endsym(*cp)) {
+		debug("eval%d symbol", prec(ops));
+		sym = findsym(&cp);
+		if (sym < 0) {
+			lt = LT_IF;
+			cp = skipargs(cp);
+		} else if (value[sym] == NULL) {
+			*valp = 0;
+			lt = LT_FALSE;
+		} else {
+			*valp = strtol(value[sym], &ep, 0);
+			if (*ep != '\0' || ep == value[sym])
+				return (LT_ERROR);
+			lt = *valp ? LT_TRUE : LT_FALSE;
+			cp = skipargs(cp);
+		}
+		constexpr = false;
+	} else {
+		debug("eval%d bad expr", prec(ops));
+		return (LT_ERROR);
+	}
+
+	*cpp = cp;
+	debug("eval%d = %d", prec(ops), *valp);
+	return (lt);
+}
+
+/*
+ * Table-driven evaluation of binary operators.
+ */
+static Linetype
+eval_table(const struct ops *ops, long *valp, const char **cpp)
+{
+	const struct op *op;
+	const char *cp;
+	long val = 0;
+	Linetype lt, rt;
+
+	debug("eval%d", prec(ops));
+	cp = *cpp;
+	lt = ops->inner(ops+1, valp, &cp);
+	if (lt == LT_ERROR)
+		return (LT_ERROR);
+	for (;;) {
+		cp = skipcomment(cp);
+		for (op = ops->op; op->str != NULL; op++) {
+			if (strncmp(cp, op->str, strlen(op->str)) == 0) {
+				/* assume only one-char operators have stop chars */
+				if (op->stop != NULL && cp[1] != '\0' &&
+				    strchr(op->stop, cp[1]) != NULL)
+					continue;
+				else
+					break;
+			}
+		}
+		if (op->str == NULL)
+			break;
+		cp += strlen(op->str);
+		debug("eval%d %s", prec(ops), op->str);
+		rt = ops->inner(ops+1, &val, &cp);
+		if (rt == LT_ERROR)
+			return (LT_ERROR);
+		lt = op->fn(valp, lt, *valp, rt, val);
+	}
+
+	*cpp = cp;
+	debug("eval%d = %d", prec(ops), *valp);
+	debug("eval%d lt = %s", prec(ops), linetype_name[lt]);
+	return (lt);
+}
+
+/*
+ * Evaluate the expression on a #if or #elif line. If we can work out
+ * the result we return LT_TRUE or LT_FALSE accordingly, otherwise we
+ * return just a generic LT_IF.
+ */
+static Linetype
+ifeval(const char **cpp)
+{
+	Linetype ret;
+	long val = 0;
+
+	debug("eval %s", *cpp);
+	constexpr = killconsts ? false : true;
+	ret = eval_table(eval_ops, &val, cpp);
+	debug("eval = %d", val);
+	return (constexpr ? LT_IF : ret == LT_ERROR ? LT_IF : ret);
+}
+
+/*
+ * Read a line and examine its initial part to determine if it is a
+ * preprocessor directive. Returns NULL on EOF, or a pointer to a
+ * preprocessor directive name, or a pointer to the zero byte at the
+ * end of the line.
+ */
+static const char *
+skiphash(void)
+{
+	const char *cp;
+
+	linenum++;
+	if (fgets(tline, MAXLINE, input) == NULL) {
+		if (ferror(input))
+			err(2, "can't read %s", filename);
+		else
+			return (NULL);
+	}
+	cp = skipcomment(tline);
+	if (linestate == LS_START && *cp == '#') {
+		linestate = LS_HASH;
+		return (skipcomment(cp + 1));
+	} else if (*cp == '\0') {
+		return (cp);
+	} else {
+		return (skipline(cp));
+	}
+}
+
+/*
+ * Mark a line dirty and consume the rest of it, keeping track of the
+ * lexical state.
+ */
+static const char *
+skipline(const char *cp)
+{
+	const char *pcp;
+	if (*cp != '\0')
+		linestate = LS_DIRTY;
+	while (*cp != '\0') {
+		cp = skipcomment(pcp = cp);
+		if (pcp == cp)
+			cp++;
+	}
+	return (cp);
+}
+
+/*
+ * Skip over comments, strings, and character literals and stop at the
+ * next character position that is not whitespace. Between calls we keep
+ * the comment state in the global variable incomment, and we also adjust
+ * the global variable linestate when we see a newline.
+ * XXX: doesn't cope with the buffer splitting inside a state transition.
+ */
+static const char *
+skipcomment(const char *cp)
+{
+	if (text || ignoring[depth]) {
+		for (; isspace((unsigned char)*cp); cp++)
+			if (*cp == '\n')
+				linestate = LS_START;
+		return (cp);
+	}
+	while (*cp != '\0')
+		/* don't reset to LS_START after a line continuation */
+		if (strncmp(cp, "\\\r\n", 3) == 0)
+			cp += 3;
+		else if (strncmp(cp, "\\\n", 2) == 0)
+			cp += 2;
+		else switch (incomment) {
+		case NO_COMMENT:
+			if (strncmp(cp, "/\\\r\n", 4) == 0) {
+				incomment = STARTING_COMMENT;
+				cp += 4;
+			} else if (strncmp(cp, "/\\\n", 3) == 0) {
+				incomment = STARTING_COMMENT;
+				cp += 3;
+			} else if (strncmp(cp, "/*", 2) == 0) {
+				incomment = C_COMMENT;
+				cp += 2;
+			} else if (strncmp(cp, "//", 2) == 0) {
+				incomment = CXX_COMMENT;
+				cp += 2;
+			} else if (strncmp(cp, "\'", 1) == 0) {
+				incomment = CHAR_LITERAL;
+				linestate = LS_DIRTY;
+				cp += 1;
+			} else if (strncmp(cp, "\"", 1) == 0) {
+				incomment = STRING_LITERAL;
+				linestate = LS_DIRTY;
+				cp += 1;
+			} else if (strncmp(cp, "R\"(", 3) == 0) {
+				incomment = RAW_STRING_LITERAL;
+				linestate = LS_DIRTY;
+				cp += 3;
+			} else if (strncmp(cp, "\n", 1) == 0) {
+				linestate = LS_START;
+				cp += 1;
+			} else if (strchr(" \r\t", *cp) != NULL) {
+				cp += 1;
+			} else
+				return (cp);
+			continue;
+		case CXX_COMMENT:
+			if (strncmp(cp, "\n", 1) == 0) {
+				incomment = NO_COMMENT;
+				linestate = LS_START;
+			}
+			cp += 1;
+			continue;
+		case CHAR_LITERAL:
+		case STRING_LITERAL:
+			if ((incomment == CHAR_LITERAL && cp[0] == '\'') ||
+			    (incomment == STRING_LITERAL && cp[0] == '\"')) {
+				incomment = NO_COMMENT;
+				cp += 1;
+			} else if (cp[0] == '\\') {
+				if (cp[1] == '\0')
+					cp += 1;
+				else
+					cp += 2;
+			} else if (strncmp(cp, "\n", 1) == 0) {
+				if (incomment == CHAR_LITERAL)
+					error("Unterminated char literal");
+				else
+					error("Unterminated string literal");
+			} else
+				cp += 1;
+			continue;
+		case RAW_STRING_LITERAL:
+			if (strncmp(cp, ")\"", 2) == 0) {
+				incomment = NO_COMMENT;
+				cp += 2;
+			} else
+				cp += 1;
+			continue;
+		case C_COMMENT:
+			if (strncmp(cp, "*\\\r\n", 4) == 0) {
+				incomment = FINISHING_COMMENT;
+				cp += 4;
+			} else if (strncmp(cp, "*\\\n", 3) == 0) {
+				incomment = FINISHING_COMMENT;
+				cp += 3;
+			} else if (strncmp(cp, "*/", 2) == 0) {
+				incomment = NO_COMMENT;
+				cp += 2;
+			} else
+				cp += 1;
+			continue;
+		case STARTING_COMMENT:
+			if (*cp == '*') {
+				incomment = C_COMMENT;
+				cp += 1;
+			} else if (*cp == '/') {
+				incomment = CXX_COMMENT;
+				cp += 1;
+			} else {
+				incomment = NO_COMMENT;
+				linestate = LS_DIRTY;
+			}
+			continue;
+		case FINISHING_COMMENT:
+			if (*cp == '/') {
+				incomment = NO_COMMENT;
+				cp += 1;
+			} else
+				incomment = C_COMMENT;
+			continue;
+		default:
+			abort(); /* bug */
+		}
+	return (cp);
+}
+
+/*
+ * Skip macro arguments.
+ */
+static const char *
+skipargs(const char *cp)
+{
+	const char *ocp = cp;
+	int level = 0;
+	cp = skipcomment(cp);
+	if (*cp != '(')
+		return (cp);
+	do {
+		if (*cp == '(')
+			level++;
+		if (*cp == ')')
+			level--;
+		cp = skipcomment(cp+1);
+	} while (level != 0 && *cp != '\0');
+	if (level == 0)
+		return (cp);
+	else
+	/* Rewind and re-detect the syntax error later. */
+		return (ocp);
+}
+
+/*
+ * Skip over an identifier.
+ */
+static const char *
+skipsym(const char *cp)
+{
+	while (!endsym(*cp))
+		++cp;
+	return (cp);
+}
+
+/*
+ * Skip whitespace and take a copy of any following identifier.
+ */
+static const char *
+getsym(const char **cpp)
+{
+	const char *cp = *cpp, *sym;
+
+	cp = skipcomment(cp);
+	cp = skipsym(sym = cp);
+	if (cp == sym)
+		return NULL;
+	*cpp = cp;
+	return (xstrdup(sym, cp));
+}
+
+/*
+ * Check that s (a symbol) matches the start of t, and that the
+ * following character in t is not a symbol character. Returns a
+ * pointer to the following character in t if there is a match,
+ * otherwise NULL.
+ */
+static const char *
+matchsym(const char *s, const char *t)
+{
+	while (*s != '\0' && *t != '\0')
+		if (*s != *t)
+			return (NULL);
+		else
+			++s, ++t;
+	if (*s == '\0' && endsym(*t))
+		return(t);
+	else
+		return(NULL);
+}
+
+/*
+ * Look for the symbol in the symbol table. If it is found, we return
+ * the symbol table index, else we return -1.
+ */
+static int
+findsym(const char **strp)
+{
+	const char *str;
+	int symind;
+
+	str = *strp;
+	*strp = skipsym(str);
+	if (symlist) {
+		if (*strp == str)
+			return (-1);
+		if (symdepth && firstsym)
+			printf("%s%3d", zerosyms ? "" : "\n", depth);
+		firstsym = zerosyms = false;
+		printf("%s%.*s%s",
+		       symdepth ? " " : "",
+		       (int)(*strp-str), str,
+		       symdepth ? "" : "\n");
+		/* we don't care about the value of the symbol */
+		return (0);
+	}
+	for (symind = 0; symind < nsyms; ++symind) {
+		if (matchsym(symname[symind], str) != NULL) {
+			debugsym("findsym", symind);
+			return (symind);
+		}
+	}
+	return (-1);
+}
+
+/*
+ * Resolve indirect symbol values to their final definitions.
+ */
+static void
+indirectsym(void)
+{
+	const char *cp;
+	int changed, sym, ind;
+
+	do {
+		changed = 0;
+		for (sym = 0; sym < nsyms; ++sym) {
+			if (value[sym] == NULL)
+				continue;
+			cp = value[sym];
+			ind = findsym(&cp);
+			if (ind == -1 || ind == sym ||
+			    *cp != '\0' ||
+			    value[ind] == NULL ||
+			    value[ind] == value[sym])
+				continue;
+			debugsym("indir...", sym);
+			value[sym] = value[ind];
+			debugsym("...ectsym", sym);
+			changed++;
+		}
+	} while (changed);
+}
+
+/*
+ * Add a symbol to the symbol table, specified with the format sym=val
+ */
+static void
+addsym1(bool ignorethis, bool definethis, char *symval)
+{
+	const char *sym, *val;
+
+	sym = symval;
+	val = skipsym(sym);
+	if (definethis && *val == '=') {
+		symval[val - sym] = '\0';
+		val = val + 1;
+	} else if (*val == '\0') {
+		val = definethis ? "1" : NULL;
+	} else {
+		usage();
+	}
+	addsym2(ignorethis, sym, val);
+}
+
+/*
+ * Add a symbol to the symbol table.
+ */
+static void
+addsym2(bool ignorethis, const char *sym, const char *val)
+{
+	const char *cp = sym;
+	int symind;
+
+	symind = findsym(&cp);
+	if (symind < 0) {
+		if (nsyms >= MAXSYMS)
+			errx(2, "too many symbols");
+		symind = nsyms++;
+	}
+	ignore[symind] = ignorethis;
+	symname[symind] = sym;
+	value[symind] = val;
+	debugsym("addsym", symind);
+}
+
+static void
+debugsym(const char *why, int symind)
+{
+	debug("%s %s%c%s", why, symname[symind],
+	    value[symind] ? '=' : ' ',
+	    value[symind] ? value[symind] : "undef");
+}
+
+/*
+ * Add symbols to the symbol table from a file containing
+ * #define and #undef preprocessor directives.
+ */
+static void
+defundefile(const char *fn)
+{
+	filename = fn;
+	input = fopen(fn, "rb");
+	if (input == NULL)
+		err(2, "can't open %s", fn);
+	linenum = 0;
+	while (defundef())
+		;
+	if (ferror(input))
+		err(2, "can't read %s", filename);
+	else
+		fclose(input);
+	if (incomment)
+		error("EOF in comment");
+}
+
+/*
+ * Read and process one #define or #undef directive
+ */
+static bool
+defundef(void)
+{
+	const char *cp, *kw, *sym, *val, *end;
+
+	cp = skiphash();
+	if (cp == NULL)
+		return (false);
+	if (*cp == '\0')
+		goto done;
+	/* strip trailing whitespace, and do a fairly rough check to
+	   avoid unsupported multi-line preprocessor directives */
+	end = cp + strlen(cp);
+	while (end > tline && strchr(" \t\n\r", end[-1]) != NULL)
+		--end;
+	if (end > tline && end[-1] == '\\')
+		Eioccc();
+
+	kw = cp;
+	if ((cp = matchsym("define", kw)) != NULL) {
+		sym = getsym(&cp);
+		if (sym == NULL)
+			error("Missing macro name in #define");
+		if (*cp == '(') {
+			val = "1";
+		} else {
+			cp = skipcomment(cp);
+			val = (cp < end) ? xstrdup(cp, end) : "";
+		}
+		debug("#define");
+		addsym2(false, sym, val);
+	} else if ((cp = matchsym("undef", kw)) != NULL) {
+		sym = getsym(&cp);
+		if (sym == NULL)
+			error("Missing macro name in #undef");
+		cp = skipcomment(cp);
+		debug("#undef");
+		addsym2(false, sym, NULL);
+	} else {
+		error("Unrecognized preprocessor directive");
+	}
+	skipline(cp);
+done:
+	debug("parser line %d state %s comment %s line", linenum,
+	    comment_name[incomment], linestate_name[linestate]);
+	return (true);
+}
+
+/*
+ * Concatenate two strings into new memory, checking for failure.
+ */
+static char *
+astrcat(const char *s1, const char *s2)
+{
+	char *s;
+	int len;
+	size_t size;
+
+	len = snprintf(NULL, 0, "%s%s", s1, s2);
+	if (len < 0)
+		err(2, "snprintf");
+	size = (size_t)len + 1;
+	s = (char *)malloc(size);
+	if (s == NULL)
+		err(2, "malloc");
+	snprintf(s, size, "%s%s", s1, s2);
+	return (s);
+}
+
+/*
+ * Duplicate a segment of a string, checking for failure.
+ */
+static const char *
+xstrdup(const char *start, const char *end)
+{
+	size_t n;
+	char *s;
+
+	if (end < start) abort(); /* bug */
+	n = (size_t)(end - start) + 1;
+	s = (char *)malloc(n);
+	if (s == NULL)
+		err(2, "malloc");
+	snprintf(s, n, "%s", start);
+	return (s);
+}
+
+/*
+ * Diagnostics.
+ */
+static void
+debug(const char *msg, ...)
+{
+	va_list ap;
+
+	if (debugging) {
+		va_start(ap, msg);
+		vwarnx(msg, ap);
+		va_end(ap);
+	}
+}
+
+static void
+error(const char *msg)
+{
+	if (depth == 0)
+		warnx("%s: %d: %s", filename, linenum, msg);
+	else
+		warnx("%s: %d: %s (#if line %d depth %d)",
+		    filename, linenum, msg, stifline[depth], depth);
+	closeio();
+	errx(2, "Output may be truncated");
+}