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revise environment handling.
Add a setenv keyword for manipulating the environment. keepenv now means
only retain everything. (for one release, the old use of keepenv will still
work.)
Allow setting variables to new or existing values, and also removing vars
when keepenv is used.
ok djm martijn tb

/* $OpenBSD: parse.y,v 1.19 2016/06/27 15:41:17 tedu Exp $ */
/*
 * Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
 *
 * 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.
 */

%{
#include <sys/types.h>
#include <ctype.h>
#include <unistd.h>
#include <stdint.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <err.h>

#include "doas.h"

typedef struct {
	union {
		struct {
			int action;
			int options;
			const char *cmd;
			const char **cmdargs;
			const char **envlist;
		};
		const char *str;
	};
	int lineno;
	int colno;
} yystype;
#define YYSTYPE yystype

FILE *yyfp;

struct rule **rules;
int nrules, maxrules;
int parse_errors = 0;
int obsolete_warned = 0;

void yyerror(const char *, ...);
int yylex(void);
int yyparse(void);

%}

%token TPERMIT TDENY TAS TCMD TARGS
%token TNOPASS TKEEPENV TSETENV
%token TSTRING

%%

grammar:	/* empty */
		| grammar '\n'
		| grammar rule '\n'
		| error '\n'
		;

rule:		action ident target cmd {
			struct rule *r;
			r = calloc(1, sizeof(*r));
			if (!r)
				errx(1, "can't allocate rule");
			r->action = $1.action;
			r->options = $1.options;
			r->envlist = $1.envlist;
			r->ident = $2.str;
			r->target = $3.str;
			r->cmd = $4.cmd;
			r->cmdargs = $4.cmdargs;
			if (nrules == maxrules) {
				if (maxrules == 0)
					maxrules = 63;
				else
					maxrules *= 2;
				if (!(rules = reallocarray(rules, maxrules,
				    sizeof(*rules))))
					errx(1, "can't allocate rules");
			}
			rules[nrules++] = r;
		} ;

action:		TPERMIT options {
			$$.action = PERMIT;
			$$.options = $2.options;
			$$.envlist = $2.envlist;
		} | TDENY {
			$$.action = DENY;
			$$.options = 0;
			$$.envlist = NULL;
		} ;

options:	/* none */ {
			$$.options = 0;
			$$.envlist = NULL;
		} | options option {
			$$.options = $1.options | $2.options;
			$$.envlist = $1.envlist;
			if ($2.envlist) {
				if ($$.envlist) {
					yyerror("can't have two setenv sections");
					YYERROR;
				} else
					$$.envlist = $2.envlist;
			}
		} ;
option:		TNOPASS {
			$$.options = NOPASS;
			$$.envlist = NULL;
		} | TKEEPENV {
			$$.options = KEEPENV;
			$$.envlist = NULL;
		} | TKEEPENV '{' envlist '}' {
			$$.options = 0;
			if (!obsolete_warned) {
				warnx("keepenv with list is obsolete");
				obsolete_warned = 1;
			}
			$$.envlist = $3.envlist;
		} | TSETENV '{' envlist '}' {
			$$.options = 0;
			$$.envlist = $3.envlist;
		} ;

envlist:	/* empty */ {
			if (!($$.envlist = calloc(1, sizeof(char *))))
				errx(1, "can't allocate envlist");
		} | envlist TSTRING {
			int nenv = arraylen($1.envlist);
			if (!($$.envlist = reallocarray($1.envlist, nenv + 2,
			    sizeof(char *))))
				errx(1, "can't allocate envlist");
			$$.envlist[nenv] = $2.str;
			$$.envlist[nenv + 1] = NULL;
		}


ident:		TSTRING {
			$$.str = $1.str;
		} ;

target:		/* optional */ {
			$$.str = NULL;
		} | TAS TSTRING {
			$$.str = $2.str;
		} ;

cmd:		/* optional */ {
			$$.cmd = NULL;
			$$.cmdargs = NULL;
		} | TCMD TSTRING args {
			$$.cmd = $2.str;
			$$.cmdargs = $3.cmdargs;
		} ;

args:		/* empty */ {
			$$.cmdargs = NULL;
		} | TARGS argslist {
			$$.cmdargs = $2.cmdargs;
		} ;

argslist:	/* empty */ {
			if (!($$.cmdargs = calloc(1, sizeof(char *))))
				errx(1, "can't allocate args");
		} | argslist TSTRING {
			int nargs = arraylen($1.cmdargs);
			if (!($$.cmdargs = reallocarray($1.cmdargs, nargs + 2,
			    sizeof(char *))))
				errx(1, "can't allocate args");
			$$.cmdargs[nargs] = $2.str;
			$$.cmdargs[nargs + 1] = NULL;
		} ;

%%

void
yyerror(const char *fmt, ...)
{
	va_list va;

	fprintf(stderr, "doas: ");
	va_start(va, fmt);
	vfprintf(stderr, fmt, va);
	va_end(va);
	fprintf(stderr, " at line %d\n", yylval.lineno + 1);
	parse_errors++;
}

struct keyword {
	const char *word;
	int token;
} keywords[] = {
	{ "deny", TDENY },
	{ "permit", TPERMIT },
	{ "as", TAS },
	{ "cmd", TCMD },
	{ "args", TARGS },
	{ "nopass", TNOPASS },
	{ "keepenv", TKEEPENV },
	{ "setenv", TSETENV },
};

int
yylex(void)
{
	char buf[1024], *ebuf, *p, *str;
	int i, c, quotes = 0, escape = 0, qpos = -1, nonkw = 0;

	p = buf;
	ebuf = buf + sizeof(buf);

repeat:
	/* skip whitespace first */
	for (c = getc(yyfp); c == ' ' || c == '\t'; c = getc(yyfp))
		yylval.colno++;

	/* check for special one-character constructions */
	switch (c) {
		case '\n':
			yylval.colno = 0;
			yylval.lineno++;
			/* FALLTHROUGH */
		case '{':
		case '}':
			return c;
		case '#':
			/* skip comments; NUL is allowed; no continuation */
			while ((c = getc(yyfp)) != '\n')
				if (c == EOF)
					goto eof;
			yylval.colno = 0;
			yylval.lineno++;
			return c;
		case EOF:
			goto eof;
	}

	/* parsing next word */
	for (;; c = getc(yyfp), yylval.colno++) {
		switch (c) {
		case '\0':
			yyerror("unallowed character NUL in column %d",
			    yylval.colno + 1);
			escape = 0;
			continue;
		case '\\':
			escape = !escape;
			if (escape)
				continue;
			break;
		case '\n':
			if (quotes)
				yyerror("unterminated quotes in column %d",
				    qpos + 1);
			if (escape) {
				nonkw = 1;
				escape = 0;
				yylval.colno = 0;
				yylval.lineno++;
				continue;
			}
			goto eow;
		case EOF:
			if (escape)
				yyerror("unterminated escape in column %d",
				    yylval.colno);
			if (quotes)
				yyerror("unterminated quotes in column %d",
				    qpos + 1);
			goto eow;
			/* FALLTHROUGH */
		case '{':
		case '}':
		case '#':
		case ' ':
		case '\t':
			if (!escape && !quotes)
				goto eow;
			break;
		case '"':
			if (!escape) {
				quotes = !quotes;
				if (quotes) {
					nonkw = 1;
					qpos = yylval.colno;
				}
				continue;
			}
		}
		*p++ = c;
		if (p == ebuf) {
			yyerror("too long line");
			p = buf;
		}
		escape = 0;
	}

eow:
	*p = 0;
	if (c != EOF)
		ungetc(c, yyfp);
	if (p == buf) {
		/*
		 * There could be a number of reasons for empty buffer,
		 * and we handle all of them here, to avoid cluttering
		 * the main loop.
		 */
		if (c == EOF)
			goto eof;
		else if (qpos == -1)    /* accept, e.g., empty args: cmd foo args "" */
			goto repeat;
	}
	if (!nonkw) {
		for (i = 0; i < sizeof(keywords) / sizeof(keywords[0]); i++) {
			if (strcmp(buf, keywords[i].word) == 0)
				return keywords[i].token;
		}
	}
	if ((str = strdup(buf)) == NULL)
		err(1, "strdup");
	yylval.str = str;
	return TSTRING;

eof:
	if (ferror(yyfp))
		yyerror("input error reading config");
	return 0;
}