/*
 * test(1); version 7-like  --  author Erik Baalbergen
 * modified by Eric Gisin to be used as built-in.
 * modified by Arnold Robbins to add SVR3 compatibility
 * (-x -c -b -p -u -g -k) plus Korn's -L -nt -ot -ef and new -S (socket).
 * modified by J.T. Conklin for NetBSD.
 *
 * This program is in the Public Domain.
 */

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

#include <fcntl.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdarg.h>
#include "bltin.h"

/* test(1) accepts the following grammar:
	oexpr	::= aexpr | aexpr "-o" oexpr ;
	aexpr	::= nexpr | nexpr "-a" aexpr ;
	nexpr	::= primary | "!" primary
	primary	::= unary-operator operand
		| operand binary-operator operand
		| operand
		| "(" oexpr ")"
		;
	unary-operator ::= "-r"|"-w"|"-x"|"-f"|"-d"|"-c"|"-b"|"-p"|
		"-u"|"-g"|"-k"|"-s"|"-t"|"-z"|"-n"|"-o"|"-O"|"-G"|"-L"|"-S";

	binary-operator ::= "="|"!="|"-eq"|"-ne"|"-ge"|"-gt"|"-le"|"-lt"|
			"-nt"|"-ot"|"-ef";
	operand ::= <any legal UNIX file name>
*/

enum token {
	EOI,
	FILRD,
	FILWR,
	FILEX,
	FILEXIST,
	FILREG,
	FILDIR,
	FILCDEV,
	FILBDEV,
	FILFIFO,
	FILSOCK,
	FILSYM,
	FILGZ,
	FILTT,
	FILSUID,
	FILSGID,
	FILSTCK,
	FILNT,
	FILOT,
	FILEQ,
	FILUID,
	FILGID,
	STREZ,
	STRNZ,
	STREQ,
	STRNE,
	STRLT,
	STRGT,
	INTEQ,
	INTNE,
	INTGE,
	INTGT,
	INTLE,
	INTLT,
	UNOT,
	BAND,
	BOR,
	LPAREN,
	RPAREN,
	OPERAND
};

enum token_types {
	UNOP,
	BINOP,
	BUNOP,
	BBINOP,
	PAREN
};

static struct t_op {
	const char *op_text;
	short op_num, op_type;
} const ops [] = {
	{"-r",	FILRD,	UNOP},
	{"-w",	FILWR,	UNOP},
	{"-x",	FILEX,	UNOP},
	{"-e",	FILEXIST,UNOP},
	{"-f",	FILREG,	UNOP},
	{"-d",	FILDIR,	UNOP},
	{"-c",	FILCDEV,UNOP},
	{"-b",	FILBDEV,UNOP},
	{"-p",	FILFIFO,UNOP},
	{"-u",	FILSUID,UNOP},
	{"-g",	FILSGID,UNOP},
	{"-k",	FILSTCK,UNOP},
	{"-s",	FILGZ,	UNOP},
	{"-t",	FILTT,	UNOP},
	{"-z",	STREZ,	UNOP},
	{"-n",	STRNZ,	UNOP},
	{"-h",	FILSYM,	UNOP},		/* for backwards compat */
	{"-O",	FILUID,	UNOP},
	{"-G",	FILGID,	UNOP},
	{"-L",	FILSYM,	UNOP},
	{"-S",	FILSOCK,UNOP},
	{"=",	STREQ,	BINOP},
	{"!=",	STRNE,	BINOP},
	{"<",	STRLT,	BINOP},
	{">",	STRGT,	BINOP},
	{"-eq",	INTEQ,	BINOP},
	{"-ne",	INTNE,	BINOP},
	{"-ge",	INTGE,	BINOP},
	{"-gt",	INTGT,	BINOP},
	{"-le",	INTLE,	BINOP},
	{"-lt",	INTLT,	BINOP},
	{"-nt",	FILNT,	BINOP},
	{"-ot",	FILOT,	BINOP},
	{"-ef",	FILEQ,	BINOP},
	{"!",	UNOT,	BUNOP},
	{"-a",	BAND,	BBINOP},
	{"-o",	BOR,	BBINOP},
	{"(",	LPAREN,	PAREN},
	{")",	RPAREN,	PAREN},
	{0,	0,	0}
};

static char **t_wp;
static struct t_op const *t_wp_op;

static void syntax(const char *, const char *);
static int oexpr(enum token);
static int aexpr(enum token);
static int nexpr(enum token);
static int primary(enum token);
static int binop(void);
static int filstat(char *, enum token);
static enum token t_lex(char **);
static int isoperand(char **);
static int newerf(const char *, const char *);
static int olderf(const char *, const char *);
static int equalf(const char *, const char *);
#if defined(HAVE_FACCESSAT) || defined(__INNOTEK_LIBC__)
static int test_file_access(const char *, int);
#else
static int test_st_mode(const struct stat64 *, int);
static int bash_group_member(gid_t);
#endif

#ifdef HAVE_FACCESSAT
# ifdef HAVE_TRADITIONAL_FACCESSAT
static inline int faccessat_confused_about_superuser(void) { return 1; }
# else
static inline int faccessat_confused_about_superuser(void) { return 0; }
# endif
#endif

static inline intmax_t getn(const char *s)
{
	return atomax10(s);
}

static const struct t_op *getop(const char *s)
{
	const struct t_op *op;

	for (op = ops; op->op_text; op++) {
		if (strcmp(s, op->op_text) == 0)
			return op;
	}

	return NULL;
}

int
testcmd(int argc, char **argv)
{
	const struct t_op *op;
	enum token n;
	int res = 1;

	if (*argv[0] == '[') {
		if (*argv[--argc] != ']')
			error("missing ]");
		argv[argc] = NULL;
	}

	t_wp_op = NULL;

recheck:
	argv++;
	argc--;

	if (argc < 1)
		return res;

	/*
	 * POSIX prescriptions: he who wrote this deserves the Nobel
	 * peace prize.
	 */
	switch (argc) {
	case 3:
		op = getop(argv[1]);
		if (op && op->op_type == BINOP) {
			n = OPERAND;
			goto eval;
		}
		/* fall through */

	case 4:
		if (!strcmp(argv[0], "(") && !strcmp(argv[argc - 1], ")")) {
			argv[--argc] = NULL;
			argv++;
			argc--;
		} else if (!strcmp(argv[0], "!")) {
			res = 0;
			goto recheck;
		}
	}

	n = t_lex(argv);

eval:
	t_wp = argv;
	res ^= oexpr(n);
	argv = t_wp;

	if (argv[0] != NULL && argv[1] != NULL)
		syntax(argv[0], "unexpected operator");

	return res;
}

static void
syntax(const char *op, const char *msg)
{
	if (op && *op)
		error("%s: %s", op, msg);
	else
		error("%s", msg);
}

static int
oexpr(enum token n)
{
	int res = 0;

	for (;;) {
		res |= aexpr(n);
		n = t_lex(t_wp + 1);
		if (n != BOR)
			break;
		n = t_lex(t_wp += 2);
	}
	return res;
}

static int
aexpr(enum token n)
{
	int res = 1;

	for (;;) {
		if (!nexpr(n))
			res = 0;
		n = t_lex(t_wp + 1);
		if (n != BAND)
			break;
		n = t_lex(t_wp += 2);
	}
	return res;
}

static int
nexpr(enum token n)
{
	if (n != UNOT)
		return primary(n);

	n = t_lex(t_wp + 1);
	if (n != EOI)
		t_wp++;
	return !nexpr(n);
}

static int
primary(enum token n)
{
	enum token nn;
	int res;

	if (n == EOI)
		return 0;		/* missing expression */
	if (n == LPAREN) {
		if ((nn = t_lex(++t_wp)) == RPAREN)
			return 0;	/* missing expression */
		res = oexpr(nn);
		if (t_lex(++t_wp) != RPAREN)
			syntax(NULL, "closing paren expected");
		return res;
	}
	if (t_wp_op && t_wp_op->op_type == UNOP) {
		/* unary expression */
		if (*++t_wp == NULL)
			syntax(t_wp_op->op_text, "argument expected");
		switch (n) {
		case STREZ:
			return strlen(*t_wp) == 0;
		case STRNZ:
			return strlen(*t_wp) != 0;
		case FILTT:
			return isatty(getn(*t_wp));
#if defined(HAVE_FACCESSAT) || defined(__INNOTEK_LIBC__)
		case FILRD:
			return test_file_access(*t_wp, R_OK);
		case FILWR:
			return test_file_access(*t_wp, W_OK);
		case FILEX:
			return test_file_access(*t_wp, X_OK);
#endif
		default:
			return filstat(*t_wp, n);
		}
	}

	if (t_lex(t_wp + 1), t_wp_op && t_wp_op->op_type == BINOP) {
		return binop();
	}

	return strlen(*t_wp) > 0;
}

static int
binop(void)
{
	const char *opnd1, *opnd2;
	struct t_op const *op;

	opnd1 = *t_wp;
	(void) t_lex(++t_wp);
	op = t_wp_op;

	if ((opnd2 = *++t_wp) == (char *)0)
		syntax(op->op_text, "argument expected");

	switch (op->op_num) {
	default:
#ifdef DEBUG
		abort();
		/* NOTREACHED */
#endif
	case STREQ:
		return strcmp(opnd1, opnd2) == 0;
	case STRNE:
		return strcmp(opnd1, opnd2) != 0;
	case STRLT:
		return strcmp(opnd1, opnd2) < 0;
	case STRGT:
		return strcmp(opnd1, opnd2) > 0;
	case INTEQ:
		return getn(opnd1) == getn(opnd2);
	case INTNE:
		return getn(opnd1) != getn(opnd2);
	case INTGE:
		return getn(opnd1) >= getn(opnd2);
	case INTGT:
		return getn(opnd1) > getn(opnd2);
	case INTLE:
		return getn(opnd1) <= getn(opnd2);
	case INTLT:
		return getn(opnd1) < getn(opnd2);
	case FILNT:
		return newerf (opnd1, opnd2);
	case FILOT:
		return olderf (opnd1, opnd2);
	case FILEQ:
		return equalf (opnd1, opnd2);
	}
}

static int
filstat(char *nm, enum token mode)
{
	struct stat64 s;

	if (mode == FILSYM ? lstat64(nm, &s) : stat64(nm, &s))
		return 0;

	switch (mode) {
#if !(defined(HAVE_FACCESSAT) || defined(__INNOTEK_LIBC__))
	case FILRD:
		return test_st_mode(&s, R_OK);
	case FILWR:
		return test_st_mode(&s, W_OK);
	case FILEX:
		return test_st_mode(&s, X_OK);
#endif
	case FILEXIST:
		return 1;
	case FILREG:
		return S_ISREG(s.st_mode);
	case FILDIR:
		return S_ISDIR(s.st_mode);
	case FILCDEV:
		return S_ISCHR(s.st_mode);
	case FILBDEV:
		return S_ISBLK(s.st_mode);
	case FILFIFO:
		return S_ISFIFO(s.st_mode);
	case FILSOCK:
		return S_ISSOCK(s.st_mode);
	case FILSYM:
		return S_ISLNK(s.st_mode);
	case FILSUID:
		return (s.st_mode & S_ISUID) != 0;
	case FILSGID:
		return (s.st_mode & S_ISGID) != 0;
	case FILSTCK:
		return (s.st_mode & S_ISVTX) != 0;
	case FILGZ:
		return !!s.st_size;
	case FILUID:
		return s.st_uid == geteuid();
	case FILGID:
		return s.st_gid == getegid();
	default:
		return 1;
	}
}

static enum token t_lex(char **tp)
{
	struct t_op const *op;
	char *s = *tp;

	if (s == 0) {
		t_wp_op = (struct t_op *)0;
		return EOI;
	}

	op = getop(s);
	if (op && !(op->op_type == UNOP && isoperand(tp)) &&
	    !(op->op_num == LPAREN && !tp[1])) {
		t_wp_op = op;
		return op->op_num;
	}

	t_wp_op = (struct t_op *)0;
	return OPERAND;
}

static int isoperand(char **tp)
{
	struct t_op const *op;
	char *s;

	if (!(s = tp[1]))
		return 1;
	if (!tp[2])
		return 0;

	op = getop(s);
	return op && op->op_type == BINOP;
}

static int
newerf (const char *f1, const char *f2)
{
	struct stat b1, b2;

	return (stat (f1, &b1) == 0 &&
		stat (f2, &b2) == 0 &&
		b1.st_mtime > b2.st_mtime);
}

static int
olderf (const char *f1, const char *f2)
{
	struct stat b1, b2;

	return (stat (f1, &b1) == 0 &&
		stat (f2, &b2) == 0 &&
		b1.st_mtime < b2.st_mtime);
}

static int
equalf (const char *f1, const char *f2)
{
	struct stat b1, b2;

	return (stat (f1, &b1) == 0 &&
		stat (f2, &b2) == 0 &&
		b1.st_dev == b2.st_dev &&
		b1.st_ino == b2.st_ino);
}

#if defined(HAVE_FACCESSAT) || defined(__INNOTEK_LIBC__)
#ifdef HAVE_FACCESSAT
static int has_exec_bit_set(const char *path)
{
	struct stat64 st;

	if (stat64(path, &st))
		return 0;
	return st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH);
}
#endif

static int test_file_access(const char *path, int mode)
{
#ifdef __INNOTEK_LIBC__
	/* kLIBC doesn't make difference between effective and real user yet
	   and Unix permission bits may be broken on some executables so fall
	   back to access() that sorts out all the details for now (note that
	   this assumes using test_file_access() instead of test_st_mode(). */
	return !access(path, mode);
#else
	if (faccessat_confused_about_superuser() &&
	    mode == X_OK && geteuid() == 0 && !has_exec_bit_set(path))
		return 0;
	return !faccessat(AT_FDCWD, path, mode, AT_EACCESS);
#endif
}
#else	/* HAVE_FACCESSAT */
/*
 * Similar to what access(2) does, but uses the effective uid and gid.
 * Doesn't make the mistake of telling root that any file is executable.
 * Returns non-zero if the file is accessible.
 */
static int
test_st_mode(const struct stat64 *st, int mode)
{
	int euid = geteuid();

	if (euid == 0) {
		/* Root can read or write any file. */
		if (mode != X_OK)
			return 1;

		/* Root can execute any file that has any one of the execute
		   bits set. */
		mode = S_IXUSR | S_IXGRP | S_IXOTH;
	} else if (st->st_uid == euid)
		mode <<= 6;
	else if (bash_group_member(st->st_gid))
		mode <<= 3;

	return st->st_mode & mode;
}

/* Return non-zero if GID is one that we have in our groups list. */
static int
bash_group_member(gid_t gid)
{
	register int i;
	gid_t *group_array;
	int ngroups;

	/* Short-circuit if possible, maybe saving a call to getgroups(). */
	if (gid == getgid() || gid == getegid())
		return (1);

	ngroups = getgroups(0, NULL);
	group_array = stalloc(ngroups * sizeof(gid_t));
	if ((getgroups(ngroups, group_array)) != ngroups)
		return (0);

	/* Search through the list looking for GID. */
	for (i = 0; i < ngroups; i++)
		if (gid == group_array[i])
			return (1);

	return (0);
}
#endif	/* HAVE_FACCESSAT */