lib/libc/gen/getusershell.c

/*
 * Copyright (c) 1985 Regents of the University of California.
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS OR CONTRIBUTORS 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getusershell.c      5.7 (Berkeley) 2/23/91";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define SHELLS "/etc/shells"

/*
 * Do not add local shells here.  They should be added in /etc/shells
 */
static char *okshells[] =
    { "/bin/sh", "/bin/csh", 0 };

static char **shells, *strings;
static char **curshell = NULL;
static char **initshells();

/*
 * Get a list of shells from SHELLS, if it exists.
 */
char *
getusershell()
{
        char *ret;

        if (curshell == NULL)
                curshell = initshells();
        ret = *curshell;
        if (ret != NULL)
                curshell++;
        return (ret);
}

void
endusershell()
{

        if (shells != NULL)
                free((char *)shells);
        shells = NULL;
        if (strings != NULL)
                free(strings);
        strings = NULL;
        curshell = NULL;
}

void
setusershell()
{

        curshell = initshells();
}

static char **
initshells()
{
        register char **sp, *cp;
        register FILE *fp;
        struct stat statb;

        if (shells != NULL)
                free((char *)shells);
        shells = NULL;
        if (strings != NULL)
                free(strings);
        strings = NULL;
        if ((fp = fopen(SHELLS, "r")) == (FILE *)0)
                return(okshells);
        if (fstat(fileno(fp), &statb) == -1) {
                (void)fclose(fp);
                return(okshells);
        }
        if ((strings = malloc((unsigned)statb.st_size)) == NULL) {
                (void)fclose(fp);
                return(okshells);
        }
        shells = (char **)calloc((unsigned)statb.st_size / 3, sizeof (char *));
        if (shells == NULL) {
                (void)fclose(fp);
                free(strings);
                strings = NULL;
                return(okshells);
        }
        sp = shells;
        cp = strings;
        while (fgets(cp, MAXPATHLEN + 1, fp) != NULL) {
                while (*cp != '#' && *cp != '/' && *cp != '\0')
                        cp++;
                if (*cp == '#' || *cp == '\0')
                        continue;
                *sp++ = cp;
                while (!isspace(*cp) && *cp != '#' && *cp != '\0')
                        cp++;
                *cp++ = '\0';
        }
        *sp = (char *)0;
        (void)fclose(fp);
        return (shells);
}