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()
   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()
   79: {
   80: 
   81:         free(shells);
   82:         shells = NULL;
   83:         free(strings);
   84:         strings = NULL;
   85:         curshell = NULL;
   86: }
   87: 
   88: void
   89: setusershell()
   90: {
   91: 
   92:         curshell = initshells();
   93: }
   94: 
   95: static char **
   96: initshells()
   97: {
   98:         register char **sp, *cp;
   99:         register FILE *fp;
  100:         struct stat64 statb;
  101:         size_t flen;
  102: 
  103:         free(shells);
  104:         shells = NULL;
  105:         free(strings);
  106:         strings = NULL;
  107:         if ((fp = fopen(_PATH_SHELLS, "rc")) == NULL)
  108:                 goto init_okshells_noclose;
  109:         if (fstat64(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:         if ((strings = malloc(statb.st_size + 2)) == NULL)
  120:                 goto init_okshells;
  121:         shells = malloc(statb.st_size / 3 * sizeof (char *));
  122:         if (shells == NULL) {
  123:                 free(strings);
  124:                 strings = NULL;
  125:                 goto init_okshells;
  126:         }
  127:         sp = shells;
  128:         cp = strings;
  129:         flen = statb.st_size + 2;
  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: }