Return to bc.y CVS log

Up to [local] / src / usr.bin / bc

rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable).  these days, people use source.  these id's do not provide
any benefit, and do hurt the small install media
(the 33,000 line diff is essentially mechanical)
ok with the idea millert, ok dms

%{
/*	$OpenBSD: bc.y,v 1.33 2009/10/27 23:59:36 deraadt Exp $	*/

/*
 * Copyright (c) 2003, Otto Moerbeek <otto@drijf.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * This implementation of bc(1) uses concepts from the original 4.4
 * BSD bc(1). The code itself is a complete rewrite, based on the
 * Posix defined bc(1) grammar. Other differences include type safe
 * usage of pointers to build the tree of emitted code, typed yacc
 * rule values, dynamic allocation of all data structures and a
 * completely rewritten lexical analyzer using lex(1).
 *
 * Some effort has been made to make sure that the generated code is
 * the same as the code generated by the older version, to provide
 * easy regression testing.
 */

#include <sys/types.h>
#include <sys/wait.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <search.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>

#include "extern.h"
#include "pathnames.h"

#define END_NODE	((ssize_t) -1)
#define CONST_STRING	((ssize_t) -2)
#define ALLOC_STRING	((ssize_t) -3)

struct tree {
	ssize_t			index;
	union {
		char		*astr;
		const char	*cstr;
	} u;
};

int			yyparse(void);
int			yywrap(void);

int			fileindex;
int			sargc;
char			**sargv;
char			*filename;
char			*cmdexpr;

static void		grow(void);
static ssize_t		cs(const char *);
static ssize_t		as(const char *);
static ssize_t		node(ssize_t, ...);
static void		emit(ssize_t);
static void		emit_macro(int, ssize_t);
static void		free_tree(void);
static ssize_t		numnode(int);
static ssize_t		lookup(char *, size_t, char);
static ssize_t		letter_node(char *);
static ssize_t		array_node(char *);
static ssize_t		function_node(char *);

static void		add_par(ssize_t);
static void		add_local(ssize_t);
static void		warning(const char *);
static void		init(void);
static __dead void	usage(void);
static char		*escape(const char *);

static ssize_t		instr_sz = 0;
static struct tree	*instructions = NULL;
static ssize_t		current = 0;
static int		macro_char = '0';
static int		reset_macro_char = '0';
static int		nesting = 0;
static int		breakstack[16];
static int		breaksp = 0;
static ssize_t		prologue;
static ssize_t		epilogue;
static bool		st_has_continue;
static char		str_table[UCHAR_MAX][2];
static bool		do_fork = true;
static u_short		var_count;
static pid_t		dc;

extern char *__progname;

#define BREAKSTACK_SZ	(sizeof(breakstack)/sizeof(breakstack[0]))

/* These values are 4.4BSD bc compatible */
#define FUNC_CHAR	0x01
#define ARRAY_CHAR	0xa1

/* Skip '\0', [, \ and ] */
#define ENCODE(c)	((c) < '[' ? (c) : (c) + 3);
#define VAR_BASE	(256-4)
#define MAX_VARIABLES	(VAR_BASE * VAR_BASE)

%}

%start program

%union {
	ssize_t		node;
	struct lvalue	lvalue;
	const char	*str;
	char		*astr;
}

%token COMMA SEMICOLON LPAR RPAR LBRACE RBRACE LBRACKET RBRACKET DOT
%token NEWLINE
%token <astr> LETTER
%token <str> NUMBER STRING
%token DEFINE BREAK QUIT LENGTH
%token RETURN FOR IF WHILE SQRT
%token SCALE IBASE OBASE AUTO
%token CONTINUE ELSE PRINT

%left BOOL_OR
%left BOOL_AND
%nonassoc BOOL_NOT
%nonassoc EQUALS LESS_EQ GREATER_EQ UNEQUALS LESS GREATER
%right <str> ASSIGN_OP
%left PLUS MINUS
%left MULTIPLY DIVIDE REMAINDER
%right EXPONENT
%nonassoc UMINUS
%nonassoc INCR DECR

%type <lvalue>	named_expression
%type <node>	argument_list
%type <node>	alloc_macro
%type <node>	expression
%type <node>	function
%type <node>	function_header
%type <node>	input_item
%type <node>	opt_argument_list
%type <node>	opt_expression
%type <node>	opt_relational_expression
%type <node>	opt_statement
%type <node>	print_expression
%type <node>	print_expression_list
%type <node>	relational_expression
%type <node>	return_expression
%type <node>	semicolon_list
%type <node>	statement
%type <node>	statement_list

%%

program		: /* empty */
		| program input_item
		;

input_item	: semicolon_list NEWLINE
			{
				emit($1);
				macro_char = reset_macro_char;
				putchar('\n');
				free_tree();
				st_has_continue = false;
			}
		| function
			{
				putchar('\n');
				free_tree();
				st_has_continue = false;
			}
		| error NEWLINE
			{
				yyerrok;
			}
		| error QUIT
			{
				yyerrok;
			}
		;

semicolon_list	: /* empty */
			{
				$$ = cs("");
			}
		| statement
		| semicolon_list SEMICOLON statement
			{
				$$ = node($1, $3, END_NODE);
			}
		| semicolon_list SEMICOLON
		;

statement_list	: /* empty */
			{
				$$ = cs("");
			}
		| statement
		| statement_list NEWLINE
		| statement_list NEWLINE statement
			{
				$$ = node($1, $3, END_NODE);
			}
		| statement_list SEMICOLON
		| statement_list SEMICOLON statement
			{
				$$ = node($1, $3, END_NODE);
			}
		;


opt_statement	: /* empty */
			{
				$$ = cs("");
			}
		| statement
		;

statement	: expression
			{
				$$ = node($1, cs("ps."), END_NODE);
			}
		| named_expression ASSIGN_OP expression
			{
				if ($2[0] == '\0')
					$$ = node($3, cs($2), $1.store,
					    END_NODE);
				else
					$$ = node($1.load, $3, cs($2), $1.store,
					    END_NODE);
			}
		| STRING
			{
				$$ = node(cs("["), as($1),
				    cs("]P"), END_NODE);
			}
		| BREAK
			{
				if (breaksp == 0) {
					warning("break not in for or while");
					YYERROR;
				} else {
					$$ = node(
					    numnode(nesting -
						breakstack[breaksp-1]),
					    cs("Q"), END_NODE);
				}
			}
		| CONTINUE
			{
				if (breaksp == 0) {
					warning("continue not in for or while");
					YYERROR;
				} else {
					st_has_continue = true;
					$$ = node(numnode(nesting -
					    breakstack[breaksp-1] - 1),
					    cs("J"), END_NODE);
				}
			}
		| QUIT
			{
				sigset_t mask;

				putchar('q');
				fflush(stdout);
				if (dc) {
					sigprocmask(SIG_BLOCK, NULL, &mask);
					sigsuspend(&mask);
				} else
					exit(0);
			}
		| RETURN return_expression
			{
				if (nesting == 0) {
					warning("return must be in a function");
					YYERROR;
				}
				$$ = $2;
			}
		| FOR LPAR alloc_macro opt_expression SEMICOLON
		     opt_relational_expression SEMICOLON
		     opt_expression RPAR opt_statement pop_nesting
			{
				ssize_t n;

				if (st_has_continue)
					n = node($10, cs("M"), $8, cs("s."),
					    $6, $3, END_NODE);
				else
					n = node($10, $8, cs("s."), $6, $3,
					    END_NODE);

				emit_macro($3, n);
				$$ = node($4, cs("s."), $6, $3, cs(" "),
				    END_NODE);
			}
		| IF LPAR alloc_macro pop_nesting relational_expression RPAR
		      opt_statement
			{
				emit_macro($3, $7);
				$$ = node($5, $3, cs(" "), END_NODE);
			}
		| IF LPAR alloc_macro pop_nesting relational_expression RPAR
		      opt_statement ELSE alloc_macro pop_nesting opt_statement
			{
				emit_macro($3, $7);
				emit_macro($9, $11);
				$$ = node($5, $3, cs("e"), $9, cs(" "),
				    END_NODE);
			}
		| WHILE LPAR alloc_macro relational_expression RPAR
		      opt_statement pop_nesting
			{
				ssize_t n;

				if (st_has_continue)
					n = node($6, cs("M"), $4, $3, END_NODE);
				else
					n = node($6, $4, $3, END_NODE);
				emit_macro($3, n);
				$$ = node($4, $3, cs(" "), END_NODE);
			}
		| LBRACE statement_list RBRACE
			{
				$$ = $2;
			}
		| PRINT print_expression_list
			{
				$$ = $2;
			}
		;

alloc_macro	: /* empty */
			{
				$$ = cs(str_table[macro_char]);
				macro_char++;
				/* Do not use [, \ and ] */
				if (macro_char == '[')
					macro_char += 3;
				/* skip letters */
				else if (macro_char == 'a')
					macro_char = '{';
				else if (macro_char == ARRAY_CHAR)
					macro_char += 26;
				else if (macro_char == 255)
					fatal("program too big");
				if (breaksp == BREAKSTACK_SZ)
					fatal("nesting too deep");
				breakstack[breaksp++] = nesting++;
			}
		;

pop_nesting	: /* empty */
			{
				breaksp--;
			}
		;

function	: function_header opt_parameter_list RPAR opt_newline
		  LBRACE NEWLINE opt_auto_define_list
		  statement_list RBRACE
			{
				int n = node(prologue, $8, epilogue,
				    cs("0"), numnode(nesting),
				    cs("Q"), END_NODE);
				emit_macro($1, n);
				reset_macro_char = macro_char;
				nesting = 0;
				breaksp = 0;
			}
		;

function_header : DEFINE LETTER LPAR
			{
				$$ = function_node($2);
				free($2);
				prologue = cs("");
				epilogue = cs("");
				nesting = 1;
				breaksp = 0;
				breakstack[breaksp] = 0;
			}
		;

opt_newline	: /* empty */
		| NEWLINE
		;

opt_parameter_list
		: /* empty */
		| parameter_list
		;


parameter_list	: LETTER
			{
				add_par(letter_node($1));
				free($1);
			}
		| LETTER LBRACKET RBRACKET
			{
				add_par(array_node($1));
				free($1);
			}
		| parameter_list COMMA LETTER
			{
				add_par(letter_node($3));
				free($3);
			}
		| parameter_list COMMA LETTER LBRACKET RBRACKET
			{
				add_par(array_node($3));
				free($3);
			}
		;



opt_auto_define_list
		: /* empty */
		| AUTO define_list NEWLINE
		| AUTO define_list SEMICOLON
		;


define_list	: LETTER
			{
				add_local(letter_node($1));
				free($1);
			}
		| LETTER LBRACKET RBRACKET
			{
				add_local(array_node($1));
				free($1);
			}
		| define_list COMMA LETTER
			{
				add_local(letter_node($3));
				free($3);
			}
		| define_list COMMA LETTER LBRACKET RBRACKET
			{
				add_local(array_node($3));
				free($3);
			}
		;


opt_argument_list
		: /* empty */
			{
				$$ = cs("");
			}
		| argument_list
		;


argument_list	: expression
		| argument_list COMMA expression
			{
				$$ = node($1, $3, END_NODE);
			}
		| argument_list COMMA LETTER LBRACKET RBRACKET
			{
				$$ = node($1, cs("l"), array_node($3),
				    END_NODE);
				free($3);
			}
		;

opt_relational_expression
		: /* empty */
			{
				$$ = cs(" 0 0=");
			}
		| relational_expression
		;

relational_expression
		: expression EQUALS expression
			{
				$$ = node($1, $3, cs("="), END_NODE);
			}
		| expression UNEQUALS expression
			{
				$$ = node($1, $3, cs("!="), END_NODE);
			}
		| expression LESS expression
			{
				$$ = node($1, $3, cs(">"), END_NODE);
			}
		| expression LESS_EQ expression
			{
				$$ = node($1, $3, cs("!<"), END_NODE);
			}
		| expression GREATER expression
			{
				$$ = node($1, $3, cs("<"), END_NODE);
			}
		| expression GREATER_EQ expression
			{
				$$ = node($1, $3, cs("!>"), END_NODE);
			}
		| expression
			{
				$$ = node($1, cs(" 0!="), END_NODE);
			}
		;


return_expression
		: /* empty */
			{
				$$ = node(cs("0"), epilogue,
				    numnode(nesting), cs("Q"), END_NODE);
			}
		| expression
			{
				$$ = node($1, epilogue,
				    numnode(nesting), cs("Q"), END_NODE);
			}
		| LPAR RPAR
			{
				$$ = node(cs("0"), epilogue,
				    numnode(nesting), cs("Q"), END_NODE);
			}
		;


opt_expression : /* empty */
			{
				$$ = cs(" 0");
			}
		| expression
		;

expression	: named_expression
			{
				$$ = node($1.load, END_NODE);
			}
		| DOT	{
				$$ = node(cs("l."), END_NODE);
			}
		| NUMBER
			{
				$$ = node(cs(" "), as($1), END_NODE);
			}
		| LPAR expression RPAR
			{
				$$ = $2;
			}
		| LETTER LPAR opt_argument_list RPAR
			{
				$$ = node($3, cs("l"),
				    function_node($1), cs("x"),
				    END_NODE);
				free($1);
			}
		| MINUS expression %prec UMINUS
			{
				$$ = node(cs(" 0"), $2, cs("-"),
				    END_NODE);
			}
		| expression PLUS expression
			{
				$$ = node($1, $3, cs("+"), END_NODE);
			}
		| expression MINUS expression
			{
				$$ = node($1, $3, cs("-"), END_NODE);
			}
		| expression MULTIPLY expression
			{
				$$ = node($1, $3, cs("*"), END_NODE);
			}
		| expression DIVIDE expression
			{
				$$ = node($1, $3, cs("/"), END_NODE);
			}
		| expression REMAINDER expression
			{
				$$ = node($1, $3, cs("%"), END_NODE);
			}
		| expression EXPONENT expression
			{
				$$ = node($1, $3, cs("^"), END_NODE);
			}
		| INCR named_expression
			{
				$$ = node($2.load, cs("1+d"), $2.store,
				    END_NODE);
			}
		| DECR named_expression
			{
				$$ = node($2.load, cs("1-d"),
				    $2.store, END_NODE);
			}
		| named_expression INCR
			{
				$$ = node($1.load, cs("d1+"),
				    $1.store, END_NODE);
			}
		| named_expression DECR
			{
				$$ = node($1.load, cs("d1-"),
				    $1.store, END_NODE);
			}
		| named_expression ASSIGN_OP expression
			{
				if ($2[0] == '\0')
					$$ = node($3, cs($2), cs("d"), $1.store,
					    END_NODE);
				else
					$$ = node($1.load, $3, cs($2), cs("d"),
					    $1.store, END_NODE);
			}
		| LENGTH LPAR expression RPAR
			{
				$$ = node($3, cs("Z"), END_NODE);
			}
		| SQRT LPAR expression RPAR
			{
				$$ = node($3, cs("v"), END_NODE);
			}
		| SCALE LPAR expression RPAR
			{
				$$ = node($3, cs("X"), END_NODE);
			}
		| BOOL_NOT expression
			{
				$$ = node($2, cs("N"), END_NODE);
			}
		| expression BOOL_AND alloc_macro pop_nesting expression
			{
				ssize_t n = node(cs("R"), $5, END_NODE);
				emit_macro($3, n);
				$$ = node($1, cs("d0!="), $3, END_NODE);
			}
		| expression BOOL_OR alloc_macro pop_nesting expression
			{
				ssize_t n = node(cs("R"), $5, END_NODE);
				emit_macro($3, n);
				$$ = node($1, cs("d0="), $3, END_NODE);
			}
		| expression EQUALS expression
			{
				$$ = node($1, $3, cs("G"), END_NODE);
			}
		| expression UNEQUALS expression
			{
				$$ = node($1, $3, cs("GN"), END_NODE);
			}
		| expression LESS expression
			{
				$$ = node($3, $1, cs("("), END_NODE);
			}
		| expression LESS_EQ expression
			{
				$$ = node($3, $1, cs("{"), END_NODE);
			}
		| expression GREATER expression
			{
				$$ = node($1, $3, cs("("), END_NODE);
			}
		| expression GREATER_EQ expression
			{
				$$ = node($1, $3, cs("{"), END_NODE);
			}
		;

named_expression
		: LETTER
			{
				$$.load = node(cs("l"), letter_node($1),
				    END_NODE);
				$$.store = node(cs("s"), letter_node($1),
				    END_NODE);
				free($1);
			}
		| LETTER LBRACKET expression RBRACKET
			{
				$$.load = node($3, cs(";"),
				    array_node($1), END_NODE);
				$$.store = node($3, cs(":"),
				    array_node($1), END_NODE);
				free($1);
			}
		| SCALE
			{
				$$.load = cs("K");
				$$.store = cs("k");
			}
		| IBASE
			{
				$$.load = cs("I");
				$$.store = cs("i");
			}
		| OBASE
			{
				$$.load = cs("O");
				$$.store = cs("o");
			}
		;

print_expression_list
		: print_expression
		| print_expression_list COMMA print_expression
			{
				$$ = node($1, $3, END_NODE);
			}

print_expression
		: expression
			{
				$$ = node($1, cs("ds.n"), END_NODE);
			}
		| STRING
			{
				char *p = escape($1);
				$$ = node(cs("["), as(p), cs("]n"), END_NODE);
				free(p);
			}
%%


static void
grow(void)
{
	struct tree	*p;
	size_t		newsize;

	if (current == instr_sz) {
		newsize = instr_sz * 2 + 1;
		p = realloc(instructions, newsize * sizeof(*p));
		if (p == NULL) {
			free(instructions);
			err(1, NULL);
		}
		instructions = p;
		instr_sz = newsize;
	}
}

static ssize_t
cs(const char *str)
{
	grow();
	instructions[current].index = CONST_STRING;
	instructions[current].u.cstr = str;
	return current++;
}

static ssize_t
as(const char *str)
{
	grow();
	instructions[current].index = ALLOC_STRING;
	instructions[current].u.astr = strdup(str);
	if (instructions[current].u.astr == NULL)
		err(1, NULL);
	return current++;
}

static ssize_t
node(ssize_t arg, ...)
{
	va_list		ap;
	ssize_t		ret;

	va_start(ap, arg);

	ret = current;
	grow();
	instructions[current++].index = arg;

	do {
		arg = va_arg(ap, ssize_t);
		grow();
		instructions[current++].index = arg;
	} while (arg != END_NODE);

	va_end(ap);
	return ret;
}

static void
emit(ssize_t i)
{
	if (instructions[i].index >= 0)
		while (instructions[i].index != END_NODE)
			emit(instructions[i++].index);
	else
		fputs(instructions[i].u.cstr, stdout);
}

static void
emit_macro(int node, ssize_t code)
{
	putchar('[');
	emit(code);
	printf("]s%s\n", instructions[node].u.cstr);
	nesting--;
}

static void
free_tree(void)
{
	ssize_t i;

	for (i = 0; i < current; i++)
		if (instructions[i].index == ALLOC_STRING)
			free(instructions[i].u.astr);
	current = 0;
}

static ssize_t
numnode(int num)
{
	const char *p;

	if (num < 10)
		p = str_table['0' + num];
	else if (num < 16)
		p = str_table['A' - 10 + num];
	else
		errx(1, "internal error: break num > 15");
	return node(cs(" "), cs(p), END_NODE);
}


static ssize_t
lookup(char * str, size_t len, char type)
{
	ENTRY	entry, *found;
	u_short	num;
	u_char	*p;

	/* The scanner allocated an extra byte already */
	if (str[len-1] != type) {
		str[len] = type;
		str[len+1] = '\0';
	}
	entry.key = str;
	found = hsearch(entry, FIND);
	if (found == NULL) {
		if (var_count == MAX_VARIABLES)
			errx(1, "too many variables");
		p = malloc(4);
		if (p == NULL)
			err(1, NULL);
		num = var_count++;
		p[0] = 255;
		p[1] = ENCODE(num / VAR_BASE + 1);
		p[2] = ENCODE(num % VAR_BASE + 1);
		p[3] = '\0';

		entry.data = (char *)p;
		entry.key = strdup(str);
		if (entry.key == NULL)
			err(1, NULL);
		found = hsearch(entry, ENTER);
		if (found == NULL)
			err(1, NULL);
	}
	return cs(found->data);
}

static ssize_t
letter_node(char *str)
{
	size_t len;

	len = strlen(str);
	if (len == 1 && str[0] != '_')
		return cs(str_table[(int)str[0]]);
	else
		return lookup(str, len, 'L');
}

static ssize_t
array_node(char *str)
{
	size_t len;

	len = strlen(str);
	if (len == 1 && str[0] != '_')
		return cs(str_table[(int)str[0] - 'a' + ARRAY_CHAR]);
	else
		return lookup(str, len, 'A');
}

static ssize_t
function_node(char *str)
{
	size_t len;

	len = strlen(str);
	if (len == 1 && str[0] != '_')
		return cs(str_table[(int)str[0] - 'a' + FUNC_CHAR]);
	else
		return lookup(str, len, 'F');
}

static void
add_par(ssize_t n)
{
	prologue = node(cs("S"), n, prologue, END_NODE);
	epilogue = node(epilogue, cs("L"), n, cs("s."), END_NODE);
}

static void
add_local(ssize_t n)
{
	prologue = node(cs("0S"), n, prologue, END_NODE);
	epilogue = node(epilogue, cs("L"), n, cs("s."), END_NODE);
}

void
yyerror(char *s)
{
	char	*str, *p;
	int	n;

	if (yyin != NULL && feof(yyin))
		n = asprintf(&str, "%s: %s:%d: %s: unexpected EOF",
		    __progname, filename, lineno, s);
	else if (isspace(yytext[0]) || !isprint(yytext[0]))
		n = asprintf(&str,
		    "%s: %s:%d: %s: ascii char 0x%02x unexpected",
		    __progname, filename, lineno, s, yytext[0]);
	else
		n = asprintf(&str, "%s: %s:%d: %s: %s unexpected",
		    __progname, filename, lineno, s, yytext);
	if (n == -1)
		err(1, NULL);

	fputs("c[", stdout);
	for (p = str; *p != '\0'; p++) {
		if (*p == '[' || *p == ']' || *p =='\\')
			putchar('\\');
		putchar(*p);
	}
	fputs("]pc\n", stdout);
	free(str);
}

void
fatal(const char *s)
{
	errx(1, "%s:%d: %s", filename, lineno, s);
}

static void
warning(const char *s)
{
	warnx("%s:%d: %s", filename, lineno, s);
}

static void
init(void)
{
	int i;

	for (i = 0; i < UCHAR_MAX; i++) {
		str_table[i][0] = i;
		str_table[i][1] = '\0';
	}
	if (hcreate(1 << 16) == 0)
		err(1, NULL);
}


static __dead void
usage(void)
{
	fprintf(stderr, "usage: %s [-cl] [-e expression] [file ...]\n",
	    __progname);
	exit(1);
}

static char *
escape(const char *str)
{
	char *ret, *p;

	ret = malloc(strlen(str) + 1);
	if (ret == NULL)
		err(1, NULL);

	p = ret;
	while (*str != '\0') {
		/*
		 * We get _escaped_ strings here. Single backslashes are
		 * already converted to double backslashes
		 */
		if (*str == '\\') {
			if (*++str == '\\') {
				switch (*++str) {
				case 'a':
					*p++ = '\a';
					break;
				case 'b':
					*p++ = '\b';
					break;
				case 'f':
					*p++ = '\f';
					break;
				case 'n':
					*p++ = '\n';
					break;
				case 'q':
					*p++ = '"';
					break;
				case 'r':
					*p++ = '\r';
					break;
				case 't':
					*p++ = '\t';
					break;
				case '\\':
					*p++ = '\\';
					break;
				}
				str++;
			} else {
				*p++ = '\\';
				*p++ = *str++;
			}
		} else
			*p++ = *str++;
	}
	*p = '\0';
	return ret;
}

/* ARGSUSED */
void
sigchld(int signo)
{
	pid_t pid;
	int status;

	for (;;) {
		pid = waitpid(dc, &status, WCONTINUED);
		if (pid == -1) {
			if (errno == EINTR)
				continue;
			_exit(0);
		}
		if (WIFEXITED(status) || WIFSIGNALED(status))
			_exit(0);
		else
			break;
	}
}

int
main(int argc, char *argv[])
{
	int	i, ch;
	int	p[2];
	char	*q;

	init();
	setlinebuf(stdout);

	sargv = malloc(argc * sizeof(char *));
	if (sargv == NULL)
		err(1, NULL);

	if ((cmdexpr = strdup("")) == NULL)
		err(1, NULL);
	/* The d debug option is 4.4 BSD bc(1) compatible */
	while ((ch = getopt(argc, argv, "cde:l")) != -1) {
		switch (ch) {
		case 'c':
		case 'd':
			do_fork = false;
			break;
		case 'e':
			q = cmdexpr;
			if (asprintf(&cmdexpr, "%s%s\n", cmdexpr, optarg) == -1)
				err(1, NULL);
			free(q);
			break;
		case 'l':
			sargv[sargc++] = _PATH_LIBB;
			break;
		default:
			usage();
		}
	}

	argc -= optind;
	argv += optind;

	interactive = isatty(STDIN_FILENO);
	for (i = 0; i < argc; i++)
		sargv[sargc++] = argv[i];

	if (do_fork) {
		if (pipe(p) == -1)
			err(1, "cannot create pipe");
		dc = fork();
		if (dc == -1)
			err(1, "cannot fork");
		else if (dc != 0) {
			signal(SIGCHLD, sigchld);
			close(STDOUT_FILENO);
			dup(p[1]);
			close(p[0]);
			close(p[1]);
		} else {
			close(STDIN_FILENO);
			dup(p[0]);
			close(p[0]);
			close(p[1]);
			execl(_PATH_DC, "dc", "-x", (char *)NULL);
			err(1, "cannot find dc");
		}
	}
	yywrap();
	return yyparse();
}