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[] = { (char *) _PATH_BSHELL, (char *) _PATH_CSHELL,
  53                             NULL };
  54 static char **curshell, **shells, *strings;
  55 static char **initshells __P((void));
  56
  57 /*
  58  * Get a list of shells from _PATH_SHELLS, if it exists.
  59  */
  60 char *
  61 getusershell()
  62 {
  63         char *ret;
  64
  65         if (curshell == NULL)
  66                 curshell = initshells();
  67         ret = *curshell;
  68         if (ret != NULL)
  69                 curshell++;
  70         return (ret);
  71 }
  72
  73 void
  74 endusershell()
  75 {
  76
  77         if (shells != NULL)
  78                 free(shells);
  79         shells = NULL;
  80         if (strings != NULL)
  81                 free(strings);
  82         strings = NULL;
  83         curshell = NULL;
  84 }
  85
  86 void
  87 setusershell()
  88 {
  89
  90         curshell = initshells();
  91 }
  92
  93 static char **
  94 initshells()
  95 {
  96         register char **sp, *cp;
  97         register FILE *fp;
  98         struct stat statb;
  99
 100         if (shells != NULL)
 101                 free(shells);
 102         shells = NULL;
 103         if (strings != NULL)
 104                 free(strings);
 105         strings = NULL;
 106         if ((fp = fopen(_PATH_SHELLS, "r")) == NULL)
 107                 return (okshells);
 108         if (fstat(fileno(fp), &statb) == -1) {
 109                 (void)fclose(fp);
 110                 return (okshells);
 111         }
 112         if ((strings = malloc((u_int)statb.st_size + 1)) == NULL) {
 113                 (void)fclose(fp);
 114                 return (okshells);
 115         }
 116         shells = calloc((unsigned)statb.st_size / 3, sizeof (char *));
 117         if (shells == NULL) {
 118                 (void)fclose(fp);
 119                 free(strings);
 120                 strings = NULL;
 121                 return (okshells);
 122         }
 123         sp = shells;
 124         cp = strings;
 125         while (fgets(cp, statb.st_size - (cp - strings), fp) != NULL) {
 126                 while (*cp != '#' && *cp != '/' && *cp != '\0')
 127                         cp++;
 128                 if (*cp == '#' || *cp == '\0')
 129                         continue;
 130                 *sp++ = cp;
 131                 while (!isspace(*cp) && *cp != '#' && *cp != '\0')
 132                         cp++;
 133                 *cp++ = '\0';
 134         }
 135         *sp = NULL;
 136         (void)fclose(fp);
 137         return (shells);
 138 }