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diff --git a/scripts/unifdef.c b/scripts/unifdef.c
new file mode 100644
index 000000000000..5384b4377333
--- /dev/null
+++ b/scripts/unifdef.c
@@ -0,0 +1,998 @@
+/*
+ * Copyright (c) 2002 - 2005 Tony Finch <dot@dotat.at>. All rights reserved.
+ *
+ * This code is 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 following copyright notice. None of its code remains
+ * in this version (though some of the names remain).
+ *
+ * Copyright (c) 1985, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * 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.
+ */
+
+#include <sys/cdefs.h>
+
+#ifndef lint
+#if 0
+static const char copyright[] =
+"@(#) Copyright (c) 1985, 1993\n\
+ The Regents of the University of California. All rights reserved.\n";
+#endif
+#ifdef __IDSTRING
+__IDSTRING(Berkeley, "@(#)unifdef.c 8.1 (Berkeley) 6/6/93");
+__IDSTRING(NetBSD, "$NetBSD: unifdef.c,v 1.8 2000/07/03 02:51:36 matt Exp $");
+__IDSTRING(dotat, "$dotat: things/unifdef.c,v 1.171 2005/03/08 12:38:48 fanf2 Exp $");
+#endif
+#endif /* not lint */
+#ifdef __FBSDID
+__FBSDID("$FreeBSD: /repoman/r/ncvs/src/usr.bin/unifdef/unifdef.c,v 1.20 2005/05/21 09:55:09 ru Exp $");
+#endif
+
+/*
+ * unifdef - remove ifdef'ed lines
+ *
+ * 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
+ *
+ * The first two items above require better buffer handling, which would
+ * also make it possible to handle all "dodgy" directives correctly.
+ */
+
+#include <ctype.h>
+#include <err.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+size_t strlcpy(char *dst, const char *src, size_t siz);
+
+/* 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_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"
+};
+
+/* 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 "" */
+} 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 4096 /* 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 complement; /* -c: do the complement */
+static bool debugging; /* -d: debugging reports */
+static bool iocccok; /* -e: fewer IOCCC errors */
+static bool killconsts; /* -k: eval constant #ifs */
+static bool lnblank; /* -l: blank deleted lines */
+static bool lnnum; /* -n: add #line directives */
+static bool symlist; /* -s: output symbol list */
+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 char tline[MAXLINE+EDITSLOP];/* input buffer plus space */
+static char *keyword; /* used for editing #elif's */
+
+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 bool keepthis; /* don't delete constant #if */
+
+static int exitstat; /* program exit status */
+
+static void addsym(bool, bool, char *);
+static void debug(const char *, ...);
+static void done(void);
+static void error(const char *);
+static int findsym(const char *);
+static void flushline(bool);
+static Linetype getline(void);
+static Linetype ifeval(const char **);
+static void ignoreoff(void);
+static void ignoreon(void);
+static void keywordedit(const char *);
+static void nest(void);
+static void process(void);
+static const char *skipcomment(const char *);
+static const char *skipsym(const char *);
+static void state(Ifstate);
+static int strlcmp(const char *, const char *, size_t);
+static void unnest(void);
+static void usage(void);
+
+#define endsym(c) (!isalpha((unsigned char)c) && !isdigit((unsigned char)c) && c != '_')
+
+/*
+ * The main program.
+ */
+int
+main(int argc, char *argv[])
+{
+ int opt;
+
+ while ((opt = getopt(argc, argv, "i:D:U:I:cdeklnst")) != -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')
+ addsym(true, true, optarg);
+ else if (opt == 'U')
+ addsym(true, false, optarg);
+ else
+ usage();
+ break;
+ case 'D': /* define a symbol */
+ addsym(false, true, optarg);
+ break;
+ case 'U': /* undef a symbol */
+ addsym(false, false, optarg);
+ break;
+ case 'I':
+ /* no-op for compatibility with cpp */
+ 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 'k': /* process constant #ifs */
+ killconsts = true;
+ break;
+ case 'l': /* blank deleted lines instead of omitting them */
+ lnblank = true;
+ break;
+ case 'n': /* add #line directive after deleted lines */
+ lnnum = true;
+ break;
+ case 's': /* only output list of symbols that control #ifs */
+ symlist = true;
+ break;
+ case 't': /* don't parse C comments */
+ text = true;
+ break;
+ default:
+ usage();
+ }
+ argc -= optind;
+ argv += optind;
+ if (argc > 1) {
+ errx(2, "can only do one file");
+ } else if (argc == 1 && strcmp(*argv, "-") != 0) {
+ filename = *argv;
+ input = fopen(filename, "r");
+ if (input == NULL)
+ err(2, "can't open %s", filename);
+ } else {
+ filename = "[stdin]";
+ input = stdin;
+ }
+ process();
+ abort(); /* bug */
+}
+
+static void
+usage(void)
+{
+ fprintf(stderr, "usage: unifdef [-cdeklnst] [-Ipath]"
+ " [-Dsym[=val]] [-Usym] [-iDsym[=val]] [-iUsym] ... [file]\n");
+ exit(2);
+}
+
+/*
+ * 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.
+ *
+ * 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(); }
+/* edit this line */
+static void Mpass (void) { strncpy(keyword, "if ", 4); Pelif(); }
+static void Mtrue (void) { keywordedit("else\n"); state(IS_TRUE_MIDDLE); }
+static void Melif (void) { keywordedit("endif\n"); state(IS_FALSE_TRAILER); }
+static void Melse (void) { keywordedit("endif\n"); 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 },
+/* 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 },
+/* 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 },
+/* 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 },
+/* 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 },
+/* 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 },
+/* 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 },
+/* 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 },
+/* 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 },
+/* 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 }
+/*TRUEI FALSEI IF TRUE FALSE ELIF ELTRUE ELFALSE ELSE ENDIF
+ TRUEI FALSEI IF TRUE FALSE ELIF ELTRUE ELFALSE ELSE ENDIF (DODGY)
+ PLAIN EOF */
+};
+
+/*
+ * State machine utility functions
+ */
+static void
+done(void)
+{
+ if (incomment)
+ error("EOF in comment");
+ exit(exitstat);
+}
+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)
+{
+ strlcpy(keyword, replacement, tline + sizeof(tline) - keyword);
+ print();
+}
+static void
+nest(void)
+{
+ depth += 1;
+ if (depth >= MAXDEPTH)
+ error("Too many levels of nesting");
+ stifline[depth] = linenum;
+}
+static void
+unnest(void)
+{
+ if (depth == 0)
+ abort(); /* bug */
+ depth -= 1;
+}
+static void
+state(Ifstate is)
+{
+ ifstate[depth] = is;
+}
+
+/*
+ * Write a line to the output or not, according to command line options.
+ */
+static void
+flushline(bool keep)
+{
+ if (symlist)
+ return;
+ if (keep ^ complement) {
+ if (lnnum && delcount > 0)
+ printf("#line %d\n", linenum);
+ fputs(tline, stdout);
+ delcount = 0;
+ } else {
+ if (lnblank)
+ putc('\n', stdout);
+ exitstat = 1;
+ delcount += 1;
+ }
+}
+
+/*
+ * The driver for the state machine.
+ */
+static void
+process(void)
+{
+ Linetype lineval;
+
+ for (;;) {
+ linenum++;
+ lineval = getline();
+ trans_table[ifstate[depth]][lineval]();
+ debug("process %s -> %s depth %d",
+ linetype_name[lineval],
+ ifstate_name[ifstate[depth]], depth);
+ }
+}
+
+/*
+ * 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
+getline(void)
+{
+ const char *cp;
+ int cursym;
+ int kwlen;
+ Linetype retval;
+ Comment_state wascomment;
+
+ if (fgets(tline, MAXLINE, input) == NULL)
+ return (LT_EOF);
+ retval = LT_PLAIN;
+ wascomment = incomment;
+ cp = skipcomment(tline);
+ if (linestate == LS_START) {
+ if (*cp == '#') {
+ linestate = LS_HASH;
+ cp = skipcomment(cp + 1);
+ } else if (*cp != '\0')
+ linestate = LS_DIRTY;
+ }
+ if (!incomment && linestate == LS_HASH) {
+ keyword = tline + (cp - tline);
+ cp = skipsym(cp);
+ kwlen = cp - keyword;
+ /* no way can we deal with a continuation inside a keyword */
+ if (strncmp(cp, "\\\n", 2) == 0)
+ Eioccc();
+ if (strlcmp("ifdef", keyword, kwlen) == 0 ||
+ strlcmp("ifndef", keyword, kwlen) == 0) {
+ 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;
+ }
+ cp = skipsym(cp);
+ } else if (strlcmp("if", keyword, kwlen) == 0)
+ retval = ifeval(&cp);
+ else if (strlcmp("elif", keyword, kwlen) == 0)
+ retval = ifeval(&cp) - LT_IF + LT_ELIF;
+ else if (strlcmp("else", keyword, kwlen) == 0)
+ retval = LT_ELSE;
+ else if (strlcmp("endif", keyword, kwlen) == 0)
+ retval = LT_ENDIF;
+ else {
+ linestate = LS_DIRTY;
+ retval = LT_PLAIN;
+ }
+ cp = skipcomment(cp);
+ if (*cp != '\0') {
+ linestate = LS_DIRTY;
+ 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;
+ }
+ if (retval != LT_PLAIN && (wascomment || incomment)) {
+ retval += LT_DODGY;
+ if (incomment)
+ linestate = LS_DIRTY;
+ }
+ /* skipcomment should have changed the state */
+ if (linestate == LS_HASH)
+ abort(); /* bug */
+ }
+ if (linestate == LS_DIRTY) {
+ while (*cp != '\0')
+ cp = skipcomment(cp + 1);
+ }
+ debug("parser %s comment %s line",
+ comment_name[incomment], linestate_name[linestate]);
+ return (retval);
+}
+
+/*
+ * These are the binary operators that are supported by the expression
+ * evaluator. Note that if support for division is added then we also
+ * need short-circuiting booleans because of divide-by-zero.
+ */
+static int op_lt(int a, int b) { return (a < b); }
+static int op_gt(int a, int b) { return (a > b); }
+static int op_le(int a, int b) { return (a <= b); }
+static int op_ge(int a, int b) { return (a >= b); }
+static int op_eq(int a, int b) { return (a == b); }
+static int op_ne(int a, int b) { return (a != b); }
+static int op_or(int a, int b) { return (a || b); }
+static int op_and(int a, int b) { return (a && b); }
+
+/*
+ * 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, or LT_IF if the
+ * expression could not be evaluated.
+ */
+struct ops;
+
+typedef Linetype eval_fn(const struct ops *, int *, 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.
+ */
+static const struct ops {
+ eval_fn *inner;
+ struct op {
+ const char *str;
+ int (*fn)(int, int);
+ } op[5];
+} eval_ops[] = {
+ { eval_table, { { "||", op_or } } },
+ { eval_table, { { "&&", op_and } } },
+ { eval_table, { { "==", op_eq },
+ { "!=", op_ne } } },
+ { eval_unary, { { "<=", op_le },
+ { ">=", op_ge },
+ { "<", op_lt },
+ { ">", op_gt } } }
+};
+
+/*
+ * Function for evaluating the innermost parts of expressions,
+ * viz. !expr (expr) defined(symbol) symbol number
+ * We reset the keepthis flag when we find a non-constant subexpression.
+ */
+static Linetype
+eval_unary(const struct ops *ops, int *valp, const char **cpp)
+{
+ const char *cp;
+ char *ep;
+ int sym;
+
+ cp = skipcomment(*cpp);
+ if (*cp == '!') {
+ debug("eval%d !", ops - eval_ops);
+ cp++;
+ if (eval_unary(ops, valp, &cp) == LT_IF)
+ return (LT_IF);
+ *valp = !*valp;
+ } else if (*cp == '(') {
+ cp++;
+ debug("eval%d (", ops - eval_ops);
+ if (eval_table(eval_ops, valp, &cp) == LT_IF)
+ return (LT_IF);
+ cp = skipcomment(cp);
+ if (*cp++ != ')')
+ return (LT_IF);
+ } else if (isdigit((unsigned char)*cp)) {
+ debug("eval%d number", ops - eval_ops);
+ *valp = strtol(cp, &ep, 0);
+ cp = skipsym(cp);
+ } else if (strncmp(cp, "defined", 7) == 0 && endsym(cp[7])) {
+ cp = skipcomment(cp+7);
+ debug("eval%d defined", ops - eval_ops);
+ if (*cp++ != '(')
+ return (LT_IF);
+ cp = skipcomment(cp);
+ sym = findsym(cp);
+ if (sym < 0)
+ return (LT_IF);
+ *valp = (value[sym] != NULL);
+ cp = skipsym(cp);
+ cp = skipcomment(cp);
+ if (*cp++ != ')')
+ return (LT_IF);
+ keepthis = false;
+ } else if (!endsym(*cp)) {
+ debug("eval%d symbol", ops - eval_ops);
+ sym = findsym(cp);
+ if (sym < 0)
+ return (LT_IF);
+ if (value[sym] == NULL)
+ *valp = 0;
+ else {
+ *valp = strtol(value[sym], &ep, 0);
+ if (*ep != '\0' || ep == value[sym])
+ return (LT_IF);
+ }
+ cp = skipsym(cp);
+ keepthis = false;
+ } else {
+ debug("eval%d bad expr", ops - eval_ops);
+ return (LT_IF);
+ }
+
+ *cpp = cp;
+ debug("eval%d = %d", ops - eval_ops, *valp);
+ return (*valp ? LT_TRUE : LT_FALSE);
+}
+
+/*
+ * Table-driven evaluation of binary operators.
+ */
+static Linetype
+eval_table(const struct ops *ops, int *valp, const char **cpp)
+{
+ const struct op *op;
+ const char *cp;
+ int val;
+
+ debug("eval%d", ops - eval_ops);
+ cp = *cpp;
+ if (ops->inner(ops+1, valp, &cp) == LT_IF)
+ return (LT_IF);
+ for (;;) {
+ cp = skipcomment(cp);
+ for (op = ops->op; op->str != NULL; op++)
+ if (strncmp(cp, op->str, strlen(op->str)) == 0)
+ break;
+ if (op->str == NULL)
+ break;
+ cp += strlen(op->str);
+ debug("eval%d %s", ops - eval_ops, op->str);
+ if (ops->inner(ops+1, &val, &cp) == LT_IF)
+ return (LT_IF);
+ *valp = op->fn(*valp, val);
+ }
+
+ *cpp = cp;
+ debug("eval%d = %d", ops - eval_ops, *valp);
+ return (*valp ? LT_TRUE : LT_FALSE);
+}
+
+/*
+ * 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)
+{
+ int ret;
+ int val;
+
+ debug("eval %s", *cpp);
+ keepthis = killconsts ? false : true;
+ ret = eval_table(eval_ops, &val, cpp);
+ debug("eval = %d", val);
+ return (keepthis ? LT_IF : ret);
+}
+
+/*
+ * 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, "\\\n", 2) == 0)
+ cp += 2;
+ else switch (incomment) {
+ case NO_COMMENT:
+ 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, "\n", 1) == 0) {
+ linestate = LS_START;
+ cp += 1;
+ } else if (strchr(" \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 C_COMMENT:
+ 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 over an identifier.
+ */
+static const char *
+skipsym(const char *cp)
+{
+ while (!endsym(*cp))
+ ++cp;
+ return (cp);
+}
+
+/*
+ * Look for the symbol in the symbol table. If is is found, we return
+ * the symbol table index, else we return -1.
+ */
+static int
+findsym(const char *str)
+{
+ const char *cp;
+ int symind;
+
+ cp = skipsym(str);
+ if (cp == str)
+ return (-1);
+ if (symlist) {
+ printf("%.*s\n", (int)(cp-str), str);
+ /* we don't care about the value of the symbol */
+ return (0);
+ }
+ for (symind = 0; symind < nsyms; ++symind) {
+ if (strlcmp(symname[symind], str, cp-str) == 0) {
+ debug("findsym %s %s", symname[symind],
+ value[symind] ? value[symind] : "");
+ return (symind);
+ }
+ }
+ return (-1);
+}
+
+/*
+ * Add a symbol to the symbol table.
+ */
+static void
+addsym(bool ignorethis, bool definethis, char *sym)
+{
+ int symind;
+ char *val;
+
+ symind = findsym(sym);
+ if (symind < 0) {
+ if (nsyms >= MAXSYMS)
+ errx(2, "too many symbols");
+ symind = nsyms++;
+ }
+ symname[symind] = sym;
+ ignore[symind] = ignorethis;
+ val = sym + (skipsym(sym) - sym);
+ if (definethis) {
+ if (*val == '=') {
+ value[symind] = val+1;
+ *val = '\0';
+ } else if (*val == '\0')
+ value[symind] = "";
+ else
+ usage();
+ } else {
+ if (*val != '\0')
+ usage();
+ value[symind] = NULL;
+ }
+}
+
+/*
+ * Compare s with n characters of t.
+ * The same as strncmp() except that it checks that s[n] == '\0'.
+ */
+static int
+strlcmp(const char *s, const char *t, size_t n)
+{
+ while (n-- && *t != '\0')
+ if (*s != *t)
+ return ((unsigned char)*s - (unsigned char)*t);
+ else
+ ++s, ++t;
+ return ((unsigned char)*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);
+ errx(2, "output may be truncated");
+}