1  /*
       2   * Copyright (c) 1985, 1993
       3   *	The Regents of the University of California.  All rights reserved.
       4   *
       5   * Redistribution and use in source and binary forms, with or without
       6   * modification, are permitted provided that the following conditions
       7   * are met:
       8   * 1. Redistributions of source code must retain the above copyright
       9   *    notice, this list of conditions and the following disclaimer.
      10   * 2. Redistributions in binary form must reproduce the above copyright
      11   *    notice, this list of conditions and the following disclaimer in the
      12   *    documentation and/or other materials provided with the distribution.
      13   * 4. Neither the name of the University nor the names of its contributors
      14   *    may be used to endorse or promote products derived from this software
      15   *    without specific prior written permission.
      16   *
      17   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
      18   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      19   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
      20   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
      21   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
      22   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
      23   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      24   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
      25   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
      26   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
      27   * SUCH DAMAGE.
      28   */
      29  
      30  #if defined(LIBC_SCCS) && !defined(lint)
      31  static char sccsid[] = "@(#)getusershell.c	8.1 (Berkeley) 6/4/93";
      32  #endif /* LIBC_SCCS and not lint */
      33  
      34  #include <sys/param.h>
      35  #include <sys/file.h>
      36  #include <sys/stat.h>
      37  #include <stdio.h>
      38  #include <stdio_ext.h>
      39  #include <ctype.h>
      40  #include <stdlib.h>
      41  #include <unistd.h>
      42  #include <paths.h>
      43  
      44  /*
      45   * Local shells should NOT be added here.  They should be added in
      46   * /etc/shells.
      47   */
      48  
      49  /* NB: we do not initialize okshells here.  The initialization needs
      50     relocations.  These interfaces are used so rarely that this is not
      51     justified.  Instead explicitly initialize the array when it is
      52     used.  */
      53  #if 0
      54  static const char *const okshells[] = { _PATH_BSHELL, _PATH_CSHELL, NULL };
      55  #else
      56  static const char *okshells[3];
      57  #endif
      58  static char **curshell, **shells, *strings;
      59  static char **initshells (void) __THROW;
      60  
      61  /*
      62   * Get a list of shells from _PATH_SHELLS, if it exists.
      63   */
      64  char *
      65  getusershell (void)
      66  {
      67  	char *ret;
      68  
      69  	if (curshell == NULL)
      70  		curshell = initshells();
      71  	ret = *curshell;
      72  	if (ret != NULL)
      73  		curshell++;
      74  	return (ret);
      75  }
      76  
      77  void
      78  endusershell (void)
      79  {
      80  
      81  	free(shells);
      82  	shells = NULL;
      83  	free(strings);
      84  	strings = NULL;
      85  	curshell = NULL;
      86  }
      87  
      88  void
      89  setusershell (void)
      90  {
      91  
      92  	curshell = initshells();
      93  }
      94  
      95  static char **
      96  initshells (void)
      97  {
      98  	char **sp, *cp;
      99  	FILE *fp;
     100  	struct __stat64_t64 statb;
     101  	size_t flen;
     102  
     103  	free(shells);
     104  	shells = NULL;
     105  	free(strings);
     106  	strings = NULL;
     107  	if ((fp = fopen(_PATH_SHELLS, "rce")) == NULL)
     108  		goto init_okshells_noclose;
     109  	if (__fstat64_time64(fileno(fp), &statb) == -1) {
     110  	init_okshells:
     111  		(void)fclose(fp);
     112  	init_okshells_noclose:
     113  		okshells[0] = _PATH_BSHELL;
     114  		okshells[1] = _PATH_CSHELL;
     115  		return (char **) okshells;
     116  	}
     117  	if (statb.st_size > ~(size_t)0 / sizeof (char *) * 3)
     118  		goto init_okshells;
     119  	flen = statb.st_size + 3;
     120  	if ((strings = malloc(flen)) == NULL)
     121  		goto init_okshells;
     122  	shells = malloc(statb.st_size / 3 * sizeof (char *));
     123  	if (shells == NULL) {
     124  		free(strings);
     125  		strings = NULL;
     126  		goto init_okshells;
     127  	}
     128  	sp = shells;
     129  	cp = strings;
     130  	while (fgets_unlocked(cp, flen - (cp - strings), fp) != NULL) {
     131  		while (*cp != '#' && *cp != '/' && *cp != '\0')
     132  			cp++;
     133  		if (*cp == '#' || *cp == '\0' || cp[1] == '\0')
     134  			continue;
     135  		*sp++ = cp;
     136  		while (!isspace(*cp) && *cp != '#' && *cp != '\0')
     137  			cp++;
     138  		*cp++ = '\0';
     139  	}
     140  	*sp = NULL;
     141  	(void)fclose(fp);
     142  	return (shells);
     143  }