misc/getusershell.c

   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 <ctype.h>
  39 #include <stdlib.h>
  40 #include <unistd.h>
  41 #include <paths.h>
  42
  43 /*
  44  * Local shells should NOT be added here.  They should be added in
  45  * /etc/shells.
  46  */
  47
  48 static const char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, NULL };
  49 static char **curshell, **shells, *strings;
  50 static char **initshells __P((void));
  51
  52 /*
  53  * Get a list of shells from _PATH_SHELLS, if it exists.
  54  */
  55 char *
  56 getusershell()
  57 {
  58         char *ret;
  59
  60         if (curshell == NULL)
  61                 curshell = initshells();
  62         ret = *curshell;
  63         if (ret != NULL)
  64                 curshell++;
  65         return (ret);
  66 }
  67
  68 void
  69 endusershell()
  70 {
  71
  72         if (shells != NULL)
  73                 free(shells);
  74         shells = NULL;
  75         if (strings != NULL)
  76                 free(strings);
  77         strings = NULL;
  78         curshell = NULL;
  79 }
  80
  81 void
  82 setusershell()
  83 {
  84
  85         curshell = initshells();
  86 }
  87
  88 static char **
  89 initshells()
  90 {
  91         register char **sp, *cp;
  92         register FILE *fp;
  93         struct stat64 statb;
  94         int flen;
  95
  96         if (shells != NULL)
  97                 free(shells);
  98         shells = NULL;
  99         if (strings != NULL)
 100                 free(strings);
 101         strings = NULL;
 102         if ((fp = fopen(_PATH_SHELLS, "r")) == NULL)
 103                 return (char **) okshells;
 104         if (fstat64(fileno(fp), &statb) == -1) {
 105                 (void)fclose(fp);
 106                 return (char **) okshells;
 107         }
 108         if ((strings = malloc((u_int)statb.st_size + 1)) == NULL) {
 109                 (void)fclose(fp);
 110                 return (char **) okshells;
 111         }
 112         shells = calloc((unsigned)statb.st_size / 3, sizeof (char *));
 113         if (shells == NULL) {
 114                 (void)fclose(fp);
 115                 free(strings);
 116                 strings = NULL;
 117                 return (char **) okshells;
 118         }
 119         sp = shells;
 120         cp = strings;
 121         flen = statb.st_size;
 122         while (fgets_unlocked(cp, flen - (cp - strings), fp) != NULL) {
 123                 while (*cp != '#' && *cp != '/' && *cp != '\0')
 124                         cp++;
 125                 if (*cp == '#' || *cp == '\0')
 126                         continue;
 127                 *sp++ = cp;
 128                 while (!isspace(*cp) && *cp != '#' && *cp != '\0')
 129                         cp++;
 130                 *cp++ = '\0';
 131         }
 132         *sp = NULL;
 133         (void)fclose(fp);
 134         return (shells);
 135 }