/*

 * Copyright (c) 1985, 1993

 *	The 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.

 * 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	8.1 (Berkeley) 6/4/93";

#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>

#include <sys/file.h>

#include <sys/stat.h>

#include <stdio.h>

#include <stdio_ext.h>

#include <ctype.h>

#include <stdlib.h>

#include <unistd.h>

#include <paths.h>

/*

 * Local shells should NOT be added here.  They should be added in

 * /etc/shells.

 */

/* NB: we do not initialize okshells here.  The initialization needs

   relocations.  These interfaces are used so rarely that this is not

   justified.  Instead explicitly initialize the array when it is

   used.  */

#if 0

static const char *const okshells[] = { _PATH_BSHELL, _PATH_CSHELL, NULL };

#else

static const char *okshells[3];

#endif

static char **curshell, **shells, *strings;

static char **initshells (void) __THROW;

/*

 * Get a list of shells from _PATH_SHELLS, if it exists.

 */

char *

getusershell (void)

{

	char *ret;

	if (curshell == NULL)

		curshell = initshells();

	ret = *curshell;

	if (ret != NULL)

		curshell++;

	return (ret);

}

void

endusershell (void)

{

	free(shells);

	shells = NULL;

	free(strings);

	strings = NULL;

	curshell = NULL;

}

void

setusershell (void)

{

	curshell = initshells();

}

static char **

initshells (void)

{

	char **sp, *cp;

	FILE *fp;

	struct stat64 statb;

	size_t flen;

	free(shells);

	shells = NULL;

	free(strings);

	strings = NULL;

	if ((fp = fopen(_PATH_SHELLS, "rce")) == NULL)

		goto init_okshells_noclose;

	if (fstat64(fileno(fp), &statb) == -1) {

	init_okshells:

		(void)fclose(fp);

	init_okshells_noclose:

		okshells[0] = _PATH_BSHELL;

		okshells[1] = _PATH_CSHELL;

		return (char **) okshells;

	}

	if (statb.st_size > ~(size_t)0 / sizeof (char *) * 3)

		goto init_okshells;

	flen = statb.st_size + 3;

	if ((strings = malloc(flen)) == NULL)

		goto init_okshells;

	shells = malloc(statb.st_size / 3 * sizeof (char *));

	if (shells == NULL) {

		free(strings);

		strings = NULL;

		goto init_okshells;

	}

	sp = shells;

	cp = strings;

	while (fgets_unlocked(cp, flen - (cp - strings), fp) != NULL) {

		while (*cp != '#' && *cp != '/' && *cp != '\0')

			cp++;

		if (*cp == '#' || *cp == '\0' || cp[1] == '\0')

			continue;

		*sp++ = cp;

		while (!isspace(*cp) && *cp != '#' && *cp != '\0')

			cp++;

		*cp++ = '\0';

	}

	*sp = NULL;

	(void)fclose(fp);

	return (shells);

}