/*
* if.c - a port of the Sixth Edition (V6) UNIX conditional command
*/
/*-
* Copyright (c) 2004-2010
* Jeffrey Allen Neitzel <jan (at) v6shell (dot) org>.
* 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 JEFFREY ALLEN NEITZEL ``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 JEFFREY ALLEN NEITZEL 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.
*
* @(#)$Id$
*/
/*
* Derived from:
* - Sixth Edition UNIX /usr/source/s1/if.c
* - Seventh Edition UNIX /usr/src/cmd/test.c
*/
/*-
* Copyright (C) Caldera International Inc. 2001-2002. 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 and documentation 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed or owned by Caldera
* International, Inc.
* 4. Neither the name of Caldera International, Inc. nor the names of other
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
* INTERNATIONAL, INC. 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 CALDERA INTERNATIONAL, INC. 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 "defs.h"
#include "err.h"
#include "pexec.h"
#include "sasignal.h"
static int ac;
static int ap;
static char **av;
static uid_t ifeuid;
/*@noreturn@*/
static void doex(bool);
static bool e1(void);
static bool e2(void);
static bool e3(void);
static bool equal(/*@null@*/ const char *, /*@null@*/ const char *);
static bool expr(void);
static bool ifaccess(/*@null@*/ const char *, int);
static bool ifstat1(/*@null@*/ const char *, mode_t);
static bool ifstat2(/*@null@*/ const char *, /*@null@*/ const char *, int);
/*@null@*/
static char *nxtarg(bool);
/*
* NAME
* if - conditional command
*
* SYNOPSIS
* if expression [command [arg ...]]
*
* DESCRIPTION
* See the if(1) manual page for full details.
*/
int
main(int argc, char **argv)
{
bool re; /* return value of expr() */
setmyerrexit(&ut_errexit);
setmyname(argv[0]);
setmypid(getpid());
ifeuid = geteuid();
/*
* Set-ID execution is not supported.
*/
if (ifeuid != getuid() || getegid() != getgid())
err(FC_ERR, FMT2S, getmyname(), ERR_SETID);
(void)sasignal(SIGCHLD, SIG_DFL);
if (argc > 1) {
ac = argc;
av = argv;
ap = 1;
re = expr();
if (re && ap < ac)
doex(!FORKED);
} else
re = false;
return re ? SH_TRUE : SH_FALSE;
}
/*
* Evaluate the expression.
* Return true (1) or false (0).
*/
static bool
expr(void)
{
bool re;
re = e1();
if (equal(nxtarg(RETERR), "-o"))
return re | expr();
ap--;
return re;
}
static bool
e1(void)
{
bool re;
re = e2();
if (equal(nxtarg(RETERR), "-a"))
return re & e1();
ap--;
return re;
}
static bool
e2(void)
{
if (equal(nxtarg(RETERR), "!"))
return !e3();
ap--;
return e3();
}
static bool
e3(void)
{
bool re;
pid_t cpid, tpid;
int cstat, d;
char *a, *b;
if ((a = nxtarg(RETERR)) == NULL)
err(FC_ERR, FMT3S, getmyname(), av[ap - 2], ERR_EXPR);
/*
* Deal w/ parentheses for grouping.
*/
if (equal(a, "(")) {
re = expr();
if (!equal(nxtarg(RETERR), ")"))
err(FC_ERR, FMT3S, getmyname(), a, ERR_PAREN);
return re;
}
/*
* Execute { command [arg ...] } to obtain its exit status.
*/
if (equal(a, "{")) {
if ((cpid = fork()) == -1)
err(FC_ERR, FMT2S, getmyname(), ERR_FORK);
if (cpid == 0)
/**** Child! ****/
doex(FORKED);
else {
/**** Parent! ****/
tpid = wait(&cstat);
while ((a = nxtarg(RETERR)) != NULL && !equal(a, "}"))
; /* nothing */
if (a == NULL)
ap--;
return (tpid == cpid && cstat == 0) ? true : false;
}
}
/*
* file existence/permission tests
*/
if (equal(a, "-e"))
return ifaccess(nxtarg(!RETERR), F_OK);
if (equal(a, "-r"))
return ifaccess(nxtarg(!RETERR), R_OK);
if (equal(a, "-w"))
return ifaccess(nxtarg(!RETERR), W_OK);
if (equal(a, "-x"))
return ifaccess(nxtarg(!RETERR), X_OK);
/*
* file existence/type tests
*/
if (equal(a, "-d"))
return ifstat1(nxtarg(!RETERR), S_IFDIR);
if (equal(a, "-f"))
return ifstat1(nxtarg(!RETERR), S_IFREG);
if (equal(a, "-h"))
return ifstat1(nxtarg(!RETERR), S_IFLNK);
if (equal(a, "-s"))
return ifstat1(nxtarg(!RETERR), F_GZ);
if (equal(a, "-t")) {
/* Does the descriptor refer to a terminal device? */
b = nxtarg(RETERR);
if (b == NULL || *b == EOS)
err(FC_ERR, FMT3S, getmyname(), a, ERR_DIGIT);
if (*b >= '0' && *b <= '9' && *(b + 1) == EOS) {
d = *b - '0';
if (IS_DIGIT(d, *b))
return isatty(d) != 0;
}
err(FC_ERR, FMT3S, getmyname(), b, ERR_NOTDIGIT);
}
/*
* binary comparisons
*/
if ((b = nxtarg(RETERR)) == NULL)
err(FC_ERR, FMT3S, getmyname(), a, ERR_OPERATOR);
if (equal(b, "="))
return equal(a, nxtarg(!RETERR));
if (equal(b, "!="))
return !equal(a, nxtarg(!RETERR));
if (equal(b, "-ot"))
return ifstat2(a, nxtarg(!RETERR), F_OT);
if (equal(b, "-nt"))
return ifstat2(a, nxtarg(!RETERR), F_NT);
if (equal(b, "-ef"))
return ifstat2(a, nxtarg(!RETERR), F_EF);
err(FC_ERR, FMT3S, getmyname(), b, ERR_OPUNKNOWN);
/*NOTREACHED*/
return false;
}
static void
doex(bool forked)
{
char **xap, **xav;
if (ap < 2 || ap > ac) /* should never (but can) be true */
err(FC_ERR, FMT2S, getmyname(), ERR_AVIINVAL);
xav = xap = &av[ap];
while (*xap != NULL) {
if (forked && equal(*xap, "}"))
break;
xap++;
}
if (forked && xap - xav > 0 && !equal(*xap, "}"))
err(FC_ERR, FMT3S, getmyname(), av[ap - 1], ERR_BRACE);
*xap = NULL;
if (xav[0] == NULL) {
if (forked)
err(FC_ERR, FMT3S, getmyname(),av[ap - 1],ERR_COMMAND);
else
/* Currently unreachable; do not remove. */
err(FC_ERR, FMT2S, getmyname(), ERR_COMMAND);
}
/* Invoke a special "exit" utility in this case. */
if (equal(xav[0], "exit")) {
(void)lseek(FD0, (off_t)0, SEEK_END);
EXIT(SH_TRUE);
}
(void)err_pexec(xav[0], xav);
}
/*
* Check access permission for file according to mode while
* dealing w/ special cases for the superuser and `-x':
* - Always grant search access on directories.
* - If not a directory, require at least one execute bit.
* Return true (1) if access is granted.
* Return false (0) if access is denied.
*/
static bool
ifaccess(const char *file, int mode)
{
struct stat sb;
bool ra;
if (file == NULL || *file == EOS)
return false;
ra = access(file, mode) == 0;
if (ra && mode == X_OK && ifeuid == 0) {
if (stat(file, &sb) < 0)
ra = false;
else if (S_ISDIR(sb.st_mode))
ra = true;
else
ra = (sb.st_mode & (S_IXUSR|S_IXGRP|S_IXOTH)) != 0;
}
return ra;
}
static bool
ifstat1(const char *file, mode_t type)
{
struct stat sb;
bool rs;
if (file == NULL || *file == EOS)
return false;
if (type == S_IFLNK) {
if (lstat(file, &sb) < 0)
rs = false;
else
rs = (sb.st_mode & S_IFMT) == type;
} else if (stat(file, &sb) < 0)
rs = false;
else if (type == S_IFDIR || type == S_IFREG)
rs = (sb.st_mode & S_IFMT) == type;
else if (type == F_GZ)
rs = sb.st_size > (off_t)0;
else
rs = false;
return rs;
}
static bool
ifstat2(const char *file1, const char *file2, int act)
{
struct stat sb1, sb2;
bool rs;
if (file1 == NULL || *file1 == EOS)
return false;
if (file2 == NULL || *file2 == EOS)
return false;
if (stat(file1, &sb1) < 0)
return false;
if (stat(file2, &sb2) < 0)
return false;
if (act == F_OT)
rs = sb1.st_mtime < sb2.st_mtime;
else if (act == F_NT)
rs = sb1.st_mtime > sb2.st_mtime;
else if (act == F_EF)
rs = sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino;
else
rs = false;
return rs;
}
static char *
nxtarg(bool reterr)
{
char *nap;
if (ap < 1 || ap > ac) /* should never (but can) be true */
err(FC_ERR, FMT2S, getmyname(), ERR_AVIINVAL);
if (ap == ac) {
if (reterr) {
ap++;
return NULL;
}
err(FC_ERR, FMT3S, getmyname(), av[ap - 1], ERR_ARGUMENT);
}
nap = av[ap];
ap++;
return nap;
}
static bool
equal(const char *a, const char *b)
{
if (a == NULL || b == NULL)
return false;
return EQUAL(a, b);
}
