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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)getusershell.c      8.1 (Berkeley) 6/4/93";
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 #include <sys/param.h>
  39 #include <sys/file.h>
  40 #include <sys/stat.h>
  41 #include <stdio.h>
  42 #include <ctype.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45 #include <paths.h>
  46
  47 /*
  48  * Local shells should NOT be added here.  They should be added in
  49  * /etc/shells.
  50  */
  51
  52 static char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, NULL };
  53 static char **curshell, **shells, *strings;
  54 static char **initshells __P((void));
  55
  56 /*
  57  * Get a list of shells from _PATH_SHELLS, if it exists.
  58  */
  59 char *
  60 getusershell()
  61 {
  62         char *ret;
  63
  64         if (curshell == NULL)
  65                 curshell = initshells();
  66         ret = *curshell;
  67         if (ret != NULL)
  68                 curshell++;
  69         return (ret);
  70 }
  71
  72 void
  73 endusershell()
  74 {
  75
  76         if (shells != NULL)
  77                 free(shells);
  78         shells = NULL;
  79         if (strings != NULL)
  80                 free(strings);
  81         strings = NULL;
  82         curshell = NULL;
  83 }
  84
  85 void
  86 setusershell()
  87 {
  88
  89         curshell = initshells();
  90 }
  91
  92 static char **
  93 initshells()
  94 {
  95         register char **sp, *cp;
  96         register FILE *fp;
  97         struct stat statb;
  98
  99         if (shells != NULL)
 100                 free(shells);
 101         shells = NULL;
 102         if (strings != NULL)
 103                 free(strings);
 104         strings = NULL;
 105         if ((fp = fopen(_PATH_SHELLS, "r")) == NULL)
 106                 return (okshells);
 107         if (fstat(fileno(fp), &statb) == -1) {
 108                 (void)fclose(fp);
 109                 return (okshells);
 110         }
 111         if ((strings = malloc((u_int)statb.st_size + 1)) == NULL) {
 112                 (void)fclose(fp);
 113                 return (okshells);
 114         }
 115         shells = calloc((unsigned)statb.st_size / 3, sizeof (char *));
 116         if (shells == NULL) {
 117                 (void)fclose(fp);
 118                 free(strings);
 119                 strings = NULL;
 120                 return (okshells);
 121         }
 122         sp = shells;
 123         cp = strings;
 124         while (fgets(cp, statb.st_size - (cp - strings), fp) != NULL) {
 125                 while (*cp != '#' && *cp != '/' && *cp != '\0')
 126                         cp++;
 127                 if (*cp == '#' || *cp == '\0')
 128                         continue;
 129                 *sp++ = cp;
 130                 while (!isspace(*cp) && *cp != '#' && *cp != '\0')
 131                         cp++;
 132                 *cp++ = '\0';
 133         }
 134         *sp = NULL;
 135         (void)fclose(fp);
 136         return (shells);
 137 }