Source Code 1994 March/Source_Code_CD-ROM_Walnut_Creek_March_1994.iso/compsrcs/unix/volume26/super

Text File | 1992-07-02 | 25.0 KB | 908 lines

Newsgroups: comp.sources.unix
From: [e-mail] (Will Deich)
Subject: v26i062: super - execute limited command set as root
Sender: [e-mail]
Approved: [e-mail]

Submitted-By: [e-mail] (Will Deich)
Posting-Number: Volume 26, Issue 62
Archive-Name: super

Super(1) is a small program that allows users to execute other programs
(particularly scripts) as root, without unduly compromising security.

Sample uses:
    -  to call a script that allows users to use mount(8) on
    cdrom's or floppy disks, but not other devices.

    -  to call a script that allows users to send STOP/CONT
    signals to certain jobs, but not others.

    -  to restrict which users may execute a setuid-root program.

    /* Will Deich
     * Caltech  105-24, Pasadena, CA 91125
     * Internet: [e-mail]
     */

#! /bin/sh
# This is a shell archive.  Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file".  To overwrite existing
# files, type "sh file -c".  You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g..  If this archive is complete, you
# will see the following message at the end:
#        "End of shell archive."
# Contents:  README Makefile approve.c getlogdir.c ingroup.c sample.tab
#   super.1 super.c word.c
# Wrapped by [e-mail] on Fri Jul  3 11:05:52 1992
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'README' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'README'\"
else
echo shar: Extracting \"'README'\" \(3178 characters\)
sed "s/^X//" >'README' <<'END_OF_FILE'
Super(1) is a small program that allows users to execute other programs
X(particularly scripts) as root, without unduly compromising security.
X
X
Sample uses:
X    -  to call a script that allows users to use mount(8) on
X    cdrom's or floppy disks, but not other devices.
X
X    -  to call a script that allows users to send STOP/CONT
X    signals to certain jobs, but not others.
X
X    -  to restrict which users may execute a setuid-root program.
X
A "super.tab" file names each command that super is willing to execute, and
says who can use it. It contains lines like:
X
X    command   fullpathname    valid-user/group ed-type patterns
X
To execute a super command, type
X
X    % super command [args...]
X
If <command> is "-h" or "-?", or missing, super prints its current
list of allowed commands, but nothing is executed.
X
If a user is allowed to execute a given <command>, the <fullpathname>
is exec'd, with <command> as argv[0].  The superuser is always
allowed to execute any super command.
X
XFor security, the environment variables are discarded, save for
TERM, LINES, and COLUMNS.  To these are added reasonable values for
IFS, PATH, USER and HOME (USER and HOME are set to the username and
login directory, respectively, of the person who who runs super).
LOGNAME is set to the same as USER.
SUPERCMD is set to the <command>.
All descriptors excepting 0,1,2 are closed.
Signals are all reset to have default handling.
X
X--------------------
X
Making and installation:
X
The makefile is only 21 lines long.  Modify it to suit yourself.
You have to be root to install super, as it must run setuid root.
X
By default, super expects to find its table of valid commands+users/groups
in /usr/local/lib/super.tab.  If you change this (it's #define'd in
super.c), you must also change the documentation.
X
A sample super.tab file is found in sample.tab.
X
X--------------------
Notes on super scripts:
X
X1.  Scripts run via super(1) must start "#!/bin/sh" (or whatever interpreter
X    is being used).
X
X2.  It's nice to be able to type something like
X    % cdmount
X    instead of
X    % super cdmount
X
X    You can make your script automatically execute super on
X    itself by starting a script in the following manner:
X
X    #!/bin/sh
X    prog=`basename $0`
X    if [ X$SUPERCMD != X$prog ] ; then
X        exec /usr/local/bin/super $prog "$@"
X    fi
X
X
X3.  Some variants of csh will not run setuid scripts unless the -b flag
X    (force a "break" from option processing) is set:
X    #!/bin/csh -fb
X
X4.  A brief security comment:
X    You must be exceedingly careful when writing scripts for super.
X    A surprising variety of seemingly-ordinary commands can, when
X    run setuid-root, be exploited to nasty purpose.  Always make your
X    scripts do as little as possible, and give the user as few options
X    as possible.
X
X    Think twice about side-effects and alternative uses of these
X    scripts.  For instance, you might write a script to allow users to
X    mount cd-rom's by executing mount(8).  But if you don't write it
X    carefully, a user could mount a floppy disk containing, say, a
X    setuid-root shell.
X
X--------------------
X
X/* Will Deich
X * Caltech  105-24, Pasadena, CA 91125
X * Internet: [e-mail]
X */
END_OF_FILE
if test 3178 -ne `wc -c <'README'`; then
    echo shar: \"'README'\" unpacked with wrong size!
fi
# end of 'README'
fi
if test -f 'Makefile' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'Makefile'\"
else
echo shar: Extracting \"'Makefile'\" \(442 characters\)
sed "s/^X//" >'Makefile' <<'END_OF_FILE'
X
BINDIR=/usr/local/bin
MANDIR=/usr/man/manl
MANEXT=l
CFLAGS= -g
X
SRC= super.c approve.c ingroup.c word.c getlogdir.c
OBJ= super.o approve.o ingroup.o word.o getlogdir.o
X
super: $(OBJ)
X    $(CC) $(CFLAGS) -o super $(OBJ)
X
install:
X    install -m 04755 -o root super $(BINDIR)
X    install super.1 $(MANDIR)/super.$(MANEXT)
X
shar: README Makefile $(SRC) super.1 sample.tab
X    shar README Makefile $(SRC) super.1 sample.tab > super.shar
X
lint:
X    lint $(SRC)
END_OF_FILE
if test 442 -ne `wc -c <'Makefile'`; then
    echo shar: \"'Makefile'\" unpacked with wrong size!
fi
# end of 'Makefile'
fi
if test -f 'approve.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'approve.c'\"
else
echo shar: Extracting \"'approve.c'\" \(5045 characters\)
sed "s/^X//" >'approve.c' <<'END_OF_FILE'
X#include <stdio.h>
X#include <string.h>
X#include <ctype.h>
X#include <pwd.h>
X
X#include "version.h"
X
static char SccsId[] = "%W%\t%G%";
X
static FILE *fp;
X
extern errno;
X
X#define MIN(a,b) ((a) < (b) ? (a) : (b))
X
extern char *user;
extern char *prog;
X
X/* Returns:
X *    - NULL ptr if error:
X *        a) username not found;
X *        b) superfile can't be opened for reading;
X *        c) no such command as usrcmd in superfile;
X *        d) user not allowed to execute this command.
X *    - ptr to empty string if all ok, but no program should be executed.
X *    - ptr to path of file to exec, if user allowed to do so.
X *    Any error also generates a message to stderr.
X
X * New calls to approve() overwrite the buffer containing the returned path.
X */
X
X#define GROUPSEP ':'    /* ok users are named as "user<GROUPSEP>group" */
X
char *
approve(superfile, usrcmd)
char *superfile;    /* file of approved commands+users */
char *usrcmd;        /* command we're to check on.
X             * If command is one of:
X             *    "" | "-h" | "-?"
X             *    then a list of super commands is printed
X             *    instead of attempting to execute anything.
X             */
X{
X    int uid;
X    struct passwd *usrpw;
X    /* has to be static: holds the returned path used by the caller. */
X    static char buf[1024];
X    char chkbuf[1024];
X    char *allusers, *line, *command, *path, *okuser, *okgroup;
X    char *msg, *word(), *re_comp();
X    int re_exec(), ingroup();
X    char *sep;
X    int i, n, givehelp, commandfound;
X    char *nil = (char *) NULL;
X    static char *empty = "";
X    void anchor();
X
X    uid = getuid();
X    usrpw = getpwuid(uid);
X    if (!usrpw) {
X    (void) fprintf(stderr,
X        "%s - approve(): Couldn't get your password entry: ", prog);
X    perror("");
X    return NULL;
X    }
X    user = usrpw->pw_name;
X
X    if ((fp = fopen(superfile, "r")) == NULL) {
X    (void) fprintf(stderr, "%s: Couldn't open valid-users text file `%s': ",
X                superfile);
X    perror("");
X    return NULL;
X    }
X
X    sep = " \t\n";        /* How to split fields on input lines */
X
X    /* Do we just give help or really match a command with this user? */
X    givehelp = (usrcmd == nil) ||
X            strcmp(usrcmd, "-h")==0 || strcmp(usrcmd, "-?")==0;
X
X    if (givehelp) {
X    (void) fprintf(stderr, "%s version %s patchlevel %s\n",
X                prog, Version, Patchlevel);
X    (void) fprintf(stderr, "Use:\n\t%s command [args]\n\n", prog);
X    (void) fprintf(stderr, "%-16s  %-24s  %s\n",
X        "Command", "Full Path           ", "Valid User:Group Patterns");
X    (void) fprintf(stderr, "%-16s  %-24s  %s\n",
X        "-------", "--------------------", "-------------------------");
X    }
X
X    commandfound = 0;
X    for (n=1; fgets(buf, sizeof(buf), fp); n++) {
X    if (!*buf || *buf == '#')    /* Skip empty lines  and comments */
X        continue;
X    line = strtok(buf, "#");        /* Strip comments */
X
X    allusers = word(buf, " \t\v", 3);    /* Find the okusernames before
X                         * carving up the line.
X                         */
X
X    command = strtok(line, sep);        /* get the command... */
X    path = strtok(nil, sep);        /* ...and its full path */
X    if (!command || !path)
X        continue;                /* Skip improper lines */
X
X    if (givehelp) {
X        (void) fprintf(stderr, "%-16s  %-24s  %s", command, path, allusers);
X        continue;
X    }
X    if (strcmp(command, usrcmd) != 0)
X        continue;                /* Skip non-matching commands */
X    commandfound++;
X
X    /* Check our user against all valid user patterns */
X    if (uid == 0)
X        return path;            /* root is always legit */
X    for (okuser = strtok(nil, sep); okuser; okuser = strtok(nil, sep)) {
X        /* Split into user,group */
X        okgroup = strchr(okuser, GROUPSEP);
X        if (okgroup && *(okgroup+1)) {
X        /* pat was "uuu:ggg or ":ggg" */
X        if (okuser == okgroup)
X            okuser = "^.*$";    /* pat was ":ggg" */
X        *okgroup++ = '\0';
X        } else {
X        /* pat was "uuu" or "uuu:" */
X        if (okgroup)
X            *okgroup = '\0';    /* pat was "uuu:" */
X        okgroup = "^.*$";
X        }
X        /* Force all matches to be anchored: prepend/append
X         * ^, $ if they haven't been put in by user
X         */
X        anchor(okuser, chkbuf);
X        if ((msg = re_comp(chkbuf)) != NULL) {
X        (void) fprintf(stderr,
X            "%s: bad pattern `%s' on line %d in %s: %s\n",
X                prog, okuser, n, superfile, msg);
X        continue;
X        }
X        if (re_exec(user) != 1)
X        continue;            /* Skip non-matched user */
X
X        anchor(okgroup, chkbuf);
X        i = ingroup(user, chkbuf);
X        if (i == -1) {
X        (void) fprintf(stderr,
X                "%s: bad pattern `%s%c%s' on line %d in %s\n",
X                prog, okuser, GROUPSEP, okgroup, n, superfile);
X        continue;
X        }
X        if (i == 1)
X        return path;            /* Matched cmd+user+group */
X    }
X    }
X    if (givehelp)
X    return empty;
X    else if (!commandfound)
X    (void) fprintf(stderr, "%s: No such super command as `%s'.\n",
X        prog, usrcmd);
X    else
X    (void) fprintf(stderr, "%s %s: Permission denied to user %s\n",
X        prog, usrcmd, user);
X    return NULL;
X}
X
void
anchor(in, out)
char *in;
char *out;
X{
X    /* Copies in to out, prefixing with "^" and suffixing with "$"
X     * if these are missing.
X     */
X    int i;
X    i = (*in != '^');
X    if (i)
X    out[0] = '^';
X    (void) strcpy(out+i, in);
X    i = strlen(out);
X    if (out[i-1] != '$')
X    out[i++] = '$';
X    out[i] = '\0';
X}
END_OF_FILE
if test 5045 -ne `wc -c <'approve.c'`; then
    echo shar: \"'approve.c'\" unpacked with wrong size!
fi
# end of 'approve.c'
fi
if test -f 'getlogdir.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'getlogdir.c'\"
else
echo shar: Extracting \"'getlogdir.c'\" \(935 characters\)
sed "s/^X//" >'getlogdir.c' <<'END_OF_FILE'
X#include <string.h>
X#include <pwd.h>
X
static char SccsId[] = "@(#)getlogdir.c    1.1\t12/13/91";
X
X#ifndef NULL
X#define NULL (char *) 0
X#endif
X
int getlogdir(user, buf)
char *user;
char *buf;
X{
X    /* Gets the login directory of the named user, and puts it into buf.
X     * If user==NULL || *user == '\0', the current user is obtained.
X     * Best if buf is MAXPATHLEN long.
X     * 0 is returned on success; -1 on error.
X     */
X
X    struct passwd *pass;
X    char *p;
X    char *getlogin();
X
X    buf[0] = '\0';
X    if (user != NULL && *user != '\0') {
X    /* Name given; use getpwnam */
X    pass = getpwnam(user);
X    } else if ((p = getlogin()) != NULL) {
X    /* No name given; use current login name */
X    pass = getpwnam(p);
X    } else {
X    /* No user given && getlogin() returned NULL; use current uid */
X    pass = getpwuid(getuid());
X    }
X
X
X    if (pass == (struct passwd *) NULL)
X    return -1;
X
X    (void) strcpy(buf, pass->pw_dir);
X
X    return 0;
X}
END_OF_FILE
if test 935 -ne `wc -c <'getlogdir.c'`; then
    echo shar: \"'getlogdir.c'\" unpacked with wrong size!
fi
# end of 'getlogdir.c'
fi
if test -f 'ingroup.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'ingroup.c'\"
else
echo shar: Extracting \"'ingroup.c'\" \(1802 characters\)
sed "s/^X//" >'ingroup.c' <<'END_OF_FILE'
X#include <grp.h>
X
static char SccsId[] = "@(#)ingroup.c    1.3\t12/21/91";
X
X/* Use:
X *    ingroup(user, gp_pat)
X * Returns:
X *    1 if the user is in a group matching the regex pattern gp_pat.
X *    0 if the user isn't in a group matching the pattern.
X *    -1 if pattern failed to compile.
X
X * SIDE-EFFECT: uses re_comp! -- messes up caller's use of same!
X
X * Uses re_{comp,exec} routines to compare.
X
X * Examples:
X *    ingroup("joe", "xyz")
X * returns !0 if user joe is in group "xyz".
X *    ingroup("joe", "xy.*")
X * returns !0 if user joe is in any group matching "xy.*".
X
X
X * If compiled with -DPROGRAM, then a small program is compiled; use is:
X *    % ingroup username pat...
X * Prints name of first matching pattern; prints nothing on no matches.
X */
X
ingroup(user, gp_pat)
char *user;
char *gp_pat;    /* pattern to match */
X{
X    char *re_comp();
X    int re_exec();
X    struct group *gp;
X    char **mem;
X    void setgrent();
X
X    if (re_comp(gp_pat) != (char *)0 )
X    return -1;
X
X    /* Search group file for groups user's in.
X     * Test for group matches wherever user belongs.
X     */
X    setgrent();
X    for (gp = getgrent(); gp; gp = getgrent()) {
X    for (mem = gp->gr_mem; *mem; mem++)
X        if (strcmp(*mem, user) == 0)
X        break;
X    if (!*mem)
X        continue;            /* not in group */
X
X    if (re_exec(gp->gr_name) == 1)    /* in group; compare gp name with pat */
X        return 1;
X    }
X    return 0;
X}
X
X#ifdef PROGRAM
X#include <stdio.h>
main(argc, argv)
int argc;
char **argv;
X{
X    char **pat;
X    int i;
X
X    if (argc < 3) {
X    (void) fprintf(stderr, "Use: %s user pat...\n", argv[0]);
X    (void) exit(1);
X    }
X    for (pat = &argv[2]; *pat; pat++) {
X    if ((i=ingroup(argv[1], *pat)) == -1)
X        (void) fprintf(stderr, "Invalid re_comp pattern ``%s''\n", *pat);
X    else if (i) {
X        puts(*pat);
X        (void) exit(0);
X    }
X    }
X}
X#endif
END_OF_FILE
if test 1802 -ne `wc -c <'ingroup.c'`; then
    echo shar: \"'ingroup.c'\" unpacked with wrong size!
fi
# end of 'ingroup.c'
fi
if test -f 'sample.tab' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'sample.tab'\"
else
echo shar: Extracting \"'sample.tab'\" \(917 characters\)
sed "s/^X//" >'sample.tab' <<'END_OF_FILE'
X# This file lists commands that super(1) will execute for you as root.
X
X# The format for data lines in this file is
X
X#    commandname   fullpathname      ed patterns for valid users/groups.
X
X# The format for a users/groups entry is
X#    user[:]   or  :group   or  user:group
X#
X# All patterns are "anchored"; i.e. they are forced to match the entire
X# username or groupname.
X
X
X# Example entry:
X
X#    doit    /usr/local/bin/doit    me you  ja.*:ok_j  :goodguys
X
X# ...allows users "me", "you", any users named "ja.*" in group "ok_j",
X# and anybody in group "goodguys" to run /usr/local/bin/doit setuid root,
X# by typing
X#    % super doit [ doit args ]
X
X# ---------------------------------------------------------------------------
X# Cmd    Full Path        Valid-User/Group Patterns
X
timeout    /usr/local/bin/timeout    :operator :wheel gv phillips srk
restart    /usr/local/bin/restart    :operator :wheel gv phillips srk
cdmount    /usr/local/bin/cdmount    .*
END_OF_FILE
if test 917 -ne `wc -c <'sample.tab'`; then
    echo shar: \"'sample.tab'\" unpacked with wrong size!
fi
# end of 'sample.tab'
fi
if test -f 'super.1' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'super.1'\"
else
echo shar: Extracting \"'super.1'\" \(2869 characters\)
sed "s/^X//" >'super.1' <<'END_OF_FILE'
X.TH SUPER 1 local
X.SH NAME
super \- execute commands setuid root.
X.SH SYNOPSIS
X.B super
X.I command
X[
X.I args
X]
X.SH DESCRIPTION
X.I Super
allows users to execute scripts (or other commands) as if they were root.
It
is intended to be a secure alternative to making scripts setuid root.
X.PP
X.I Super
consults a file to see if the user is allowed to execute the requested
X.IR command .
If so,
X.I super
will exec
X.IR command\  [\  args\  ].
Root is always permitted to execute any command in the
super file.
X.PP
X.I Super
without any arguments will display its list of commands and their allowed users.
X.PP
XFor security, the following precautions are taken before exec'ing:
X.HP
X\fI(a)\fP    all descriptors save 0,1,2 are closed;
X.HP
X\fI(b)\fP    all of the user's environment variables are
discarded, save for TERM, LINES, and COLUMNS.  To these
are added reasonable values for:
X.RS
X.HP
USER and LOGNAME: both are set to the username
of the real user running
X.IR super ;
X.HP
HOME: set to the login directory
of the real user running
X.IR super ;
X.HP
IFS: set to blank, tab, newline;
X.HP
PATH: set to \fI/bin:/usr/bin:/usr/ucb\fP.
X.HP
SUPERCMD: set to \fIcommand\fP.
X.RE
X.in -.5i
X.HP
X\fI(c)\fP    all signal handling is reset to the default.
X.SH OPTIONS
X.HP
X.BR \-h \ |\  \-?
If no arguments are given, or if the first argument is ``\-h'' or ``\-?'',
X.I super
prints a usage line and lists all the available commands.
X.SH FILES
X.HP
X.I /usr/local/lib/super.tab
X\(em contains the list of commands that
X.I super
may execute, along with the names of the users who may execute each
command.
X.SH CREATING SUPER SCRIPTS
You must be exceedingly careful when writing scripts for
X.IR super .
A surprising variety of ordinary commands can, when
run setuid-root, be exploited for nasty purposes.  Always make your
scripts do as little as possible, and give the user as few options
as possible.
X.PP
Think twice about side-effects and alternative uses
of these scripts.  For instance, you might write a script to allow
users to mount cd-rom's by executing
X.IR mount(8) .
But if you don't write it carefully, a user could mount a floppy
disk containing, say, a setuid-root shell.
X.PP
Security issues aside, here are some hints on creating super scripts:
X.HP
X1.    Scripts must begin with
X.BI #! interpreter-path .
X.HP
X2.    Some variants of csh will not run setuid scripts unless the \-b flag
X(force a "break" from option processing) is set:
X.ti +.5i
X#!/bin/csh -fb
X.br
X.HP
X3.    It's nice to make the
X.I super
call transparent to users, so that they can type
X.ti +.5i
X% cdmount \fIargs\fP
X.br
instead of
X.ti +.5i
X% super cdmount \fIargs\fP
X.br
You can make a script
X.I super
itself by beginning the script in the following way:
X.in +.5i
X.nf
X#!/bin/sh
prog=`basename $0`
if [ X$SUPERCMD != X$prog ] ; then
X    exec /usr/local/bin/super $prog "$@"
fi
X.fi
X.in -1i
X.SH AUTHOR
Will Deich
X.br
[e-mail]
END_OF_FILE
if test 2869 -ne `wc -c <'super.1'`; then
    echo shar: \"'super.1'\" unpacked with wrong size!
fi
# end of 'super.1'
fi
if test -f 'super.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'super.c'\"
else
echo shar: Extracting \"'super.c'\" \(3952 characters\)
sed "s/^X//" >'super.c' <<'END_OF_FILE'
X#include <stdio.h>
X#include <string.h>
X#include <signal.h>
X#include <sys/param.h>
X
X#include "version.h"
X
static char SccsId[] = "%W%\t%G%";
X
X#ifndef SUPERTAB
X#define SUPERTAB "/usr/local/lib/super.tab"
X#endif
X
X/*
X * Super allows users to execute other programs (particularly
X * scripts) as root, without unduly compromising security.
X *
X * Use:
X *
X *     $0 commandname args...
X *
X * If the commandname is "-h" or "-?", or missing, super prints its current
X * list of allowed commands, but nothing executed.
X *
X * The super.tab file names each command that super will execute, and
X * says who can use it. It contains lines like:
X *
X *     commandname   fullpathname    valid-user/group ed-type patterns
X *
X * See sample.tab for how to specify user & group patterns.
X * If a user is allowed to execute a given <commandname>, the <fullpathname>
X * is exec'd, with <commandname> as argv[0].
X *
X * For security, the environment variables are discarded, save for
X * TERM, LINES, and COLUMNS.  To these are added reasonable values for
X * IFS, PATH, USER and HOME (USER and HOME are set to the username and
X * login directory, respectively, of the person who who runs super).
X * LOGNAME is set to the same as USER.
X * Finally, SUPERCMD is set to the name of the super command
X * being executed.  All descriptors excepting 0,1,2 are closed.
X * Signals are all reset to have default handling.
X */
X
static char *SAFE_IFS = "IFS= \t\n";
static char *SAFE_PATH = "PATH=/bin:/usr/bin:/usr/ucb";
X
char *prog;    /* This program */
char *user;    /* who's invoking prog */
X
main(argc, argv)
int argc;
char **argv;
X{
X    char *s, *path, *approve();
X    char **buttonup(), **envp;
X    void exit();
X
X    s = strchr(argv[0], '/');
X    prog = (s && *(s+1)) ? s+1 : argv[0];
X
X    if ((path = approve(SUPERTAB, argv[1])) == NULL)
X    (void) exit(1);
X    else if (*path == '\0')
X    (void) exit(0);
X
X    /* Button up for security, and get a modified environment */
X    envp = buttonup(argv[1]);
X
X    if (execve(path, &argv[1], envp) == -1) {
X    (void) fprintf(stderr, "%s: Couldn't exec %s (%s): ",
X                    prog, argv[1], path);
X    perror("");
X    (void) exit(1);
X    }
X    return 0;
X}
X
char **
buttonup(cmd)
char *cmd;    /* name of command being started */
X{
X    /* Closes all descriptors save 0,1,2.
X     * Resets all signal-handling to SIG_DFL.
X     * Discards all env. variables save for TERM, LINES, and COLUMNS.
X     * To these are added reasonable values for IFS, PATH, USER, and HOME.
X     * LOGNAME is set to the same as USER, and SUPERCMD is set to cmd.
X     * Returned:
X     *    a pointer to the modified environment list.
X     */
X    int i, fd, n;
X    char *Getenv();
X    int getlogdir();
X    static char *env[10];
X    static char User[100];        /* USER */
X    static char Logname[100];        /* LOGNAME (alias for USER) */
X    static char Home[MAXPATHLEN+5];    /* HOME */
X    static char Cmd[1200];        /* SUPERCMD */
X    void (*signal())();
X
X    n = getdtablesize();
X    for (fd=3; fd < n; fd++)
X    (void) close(fd);
X
X    for (i=0; i<NSIG; i++)
X       (void) signal(i, SIG_DFL);
X
X    (void) sprintf(User, "USER=%s", user);
X    (void) sprintf(Logname, "LOGNAME=%s", user);
X    (void) sprintf(Cmd, "SUPERCMD=%s", cmd);
X    (void) strcpy(Home, "HOME=");
X    (void) getlogdir(user, Home+5);
X    i = 0;
X    env[i] = Getenv("TERM");    if (env[i]) i++;
X    env[i] = Getenv("LINES");    if (env[i]) i++;
X    env[i] = Getenv("COLUMNS");    if (env[i]) i++;
X    env[i++] = SAFE_IFS;
X    env[i++] = SAFE_PATH;
X    env[i++] = User;
X    env[i++] = Logname;
X    env[i++] = Cmd;
X    env[i] = (char *) NULL;
X
X    return &env[0];
X}
X
char *
Getenv(s)
char *s;
X{
X    /* Like getenv(), but returns ptr to the <name> in "name=xxxx",
X     * not just the xxxx.
X     */
X    char **envp;
X    int l;
X    extern char **environ;
X
X    if (!s)
X    return (char *) NULL;
X    l = strlen(s);
X    for (envp=environ; *envp ; envp++)
X    if (strncmp(*envp, s, l) == 0  &&  *(*envp+l) == '=')
X        return *envp;
X    return (char *) NULL;
X}
END_OF_FILE
if test 3952 -ne `wc -c <'super.c'`; then
    echo shar: \"'super.c'\" unpacked with wrong size!
fi
# end of 'super.c'
fi
if test -f 'word.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'word.c'\"
else
echo shar: Extracting \"'word.c'\" \(1225 characters\)
sed "s/^X//" >'word.c' <<'END_OF_FILE'
X#include <ctype.h>
X
static char SccsId[] = "@(#)word.c    1.1\t12/4/91";
X
X/* Returns a pointer to the start of the k'th word in s.
X * Numbering is that k=1 for the first word.
X * A pointer to a null string is returned if there is no k'th word.
X */
X
X/*
X * Compile with -DPROGRAM to get a standalone program that's used as
X *     $0  k  string
X * and prints the k'th whitespace-separated word of the string on stdout.
X */
X
char *
word(s, sep, k)
register char *s;
register char *sep;    /* word separators */
int k;
X{
X    int i;
X
X    /* Skip leading separators */
X    s += strspn(s, sep);
X
X    /* Skip words before the k'th word */
X    for (i=1; i<k; i++) {
X    if (*s) s += strcspn(s, sep);    /* Skip a word... */
X    if (*s) s += strspn(s, sep);    /* ...and the trailing separators */
X    }
X    return s;
X}
X
X#ifdef PROGRAM
X#include <stdio.h>
X#include <string.h>
main(argc, argv)
int argc;
char **argv;
X{
X    char *prog, *word();
X    int atoi();
X
X    prog = strrchr(argv[0], '/');
X    prog = (prog && *(prog+1)) ? prog+1 : (prog) ? prog : argv[0];
X    if (argc != 3) {
X    (void) fprintf(stderr, "Usage: %s  k  \"string\"\n", prog);
X    (void) exit(1);
X    }
X    printf("%s\n", word(argv[2], " \t\v", atoi(argv[1])));
X    return 0;
X}
X#endif
END_OF_FILE
if test 1225 -ne `wc -c <'word.c'`; then
    echo shar: \"'word.c'\" unpacked with wrong size!
fi
# end of 'word.c'
fi
echo shar: End of shell archive.
exit 0