lib/libc/gen/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  * $FreeBSD: src/lib/libc/gen/getusershell.c,v 1.3.2.1 2001/03/05 09:17:52 obrien Exp $
  34  * $DragonFly: src/lib/libc/gen/getusershell.c,v 1.4 2005/11/13 00:07:42 swildner Exp $
  35  *
  36  * @(#)getusershell.c   8.1 (Berkeley) 6/4/93
  37  * $FreeBSD: src/lib/libc/gen/getusershell.c,v 1.3.2.1 2001/03/05 09:17:52 obrien Exp $
  38  */
  39
  40 #include <sys/param.h>
  41 #include <sys/file.h>
  42 #include <sys/stat.h>
  43
  44 #include <ctype.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <unistd.h>
  48 #include <paths.h>
  49
  50 /*
  51  * Local shells should NOT be added here.  They should be added in
  52  * /etc/shells.
  53  */
  54
  55 static char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, NULL };
  56 static char **curshell, **shells, *strings;
  57 static char **initshells (void);
  58
  59 /*
  60  * Get a list of shells from _PATH_SHELLS, if it exists.
  61  */
  62 char *
  63 getusershell(void)
  64 {
  65         char *ret;
  66
  67         if (curshell == NULL)
  68                 curshell = initshells();
  69         ret = *curshell;
  70         if (ret != NULL)
  71                 curshell++;
  72         return (ret);
  73 }
  74
  75 void
  76 endusershell(void)
  77 {
  78
  79         if (shells != NULL)
  80                 free(shells);
  81         shells = NULL;
  82         if (strings != 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 stat statb;
 101
 102         if (shells != NULL)
 103                 free(shells);
 104         shells = NULL;
 105         if (strings != NULL)
 106                 free(strings);
 107         strings = NULL;
 108         if ((fp = fopen(_PATH_SHELLS, "r")) == NULL)
 109                 return (okshells);
 110         if (fstat(fileno(fp), &statb) == -1) {
 111                 fclose(fp);
 112                 return (okshells);
 113         }
 114         if ((strings = malloc((u_int)statb.st_size)) == NULL) {
 115                 fclose(fp);
 116                 return (okshells);
 117         }
 118         shells = calloc((unsigned)statb.st_size / 3, sizeof (char *));
 119         if (shells == NULL) {
 120                 fclose(fp);
 121                 free(strings);
 122                 strings = NULL;
 123                 return (okshells);
 124         }
 125         sp = shells;
 126         cp = strings;
 127         while (fgets(cp, MAXPATHLEN + 1, fp) != NULL) {
 128                 while (*cp != '#' && *cp != '/' && *cp != '\0')
 129                         cp++;
 130                 if (*cp == '#' || *cp == '\0')
 131                         continue;
 132                 *sp++ = cp;
 133                 while (!isspace((unsigned char)*cp) && *cp != '#' && *cp != '\0')
 134                         cp++;
 135                 *cp++ = '\0';
 136         }
 137         *sp = NULL;
 138         fclose(fp);
 139         return (shells);
 140 }