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getusershell.c revision 1.3 
      1 /*
      2  * Copyright (c) 1985 Regents of the University of California.
      3  * 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[] = "from: @(#)getusershell.c	5.7 (Berkeley) 2/23/91";*/
     36 static char rcsid[] = "$Id: getusershell.c,v 1.3 1993/08/25 22:24:50 jtc Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/param.h>
     40 #include <sys/file.h>
     41 #include <sys/stat.h>
     42 #include <ctype.h>
     43 #include <stdio.h>
     44 #include <stdlib.h>
     45 #include <unistd.h>
     46 
     47 #define SHELLS "/etc/shells"
     48 
     49 /*
     50  * Do not add local shells here.  They should be added in /etc/shells
     51  */
     52 static char *okshells[] =
     53     { "/bin/sh", "/bin/csh", 0 };
     54 
     55 static char **shells, *strings;
     56 static char **curshell = NULL;
     57 static char **initshells();
     58 
     59 /*
     60  * Get a list of shells from SHELLS, if it exists.
     61  */
     62 char *
     63 getusershell()
     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()
     77 {
     78 
     79 	if (shells != NULL)
     80 		free((char *)shells);
     81 	shells = NULL;
     82 	if (strings != 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 stat statb;
    101 
    102 	if (shells != NULL)
    103 		free((char *)shells);
    104 	shells = NULL;
    105 	if (strings != NULL)
    106 		free(strings);
    107 	strings = NULL;
    108 	if ((fp = fopen(SHELLS, "r")) == (FILE *)0)
    109 		return(okshells);
    110 	if (fstat(fileno(fp), &statb) == -1) {
    111 		(void)fclose(fp);
    112 		return(okshells);
    113 	}
    114 	if ((strings = malloc((unsigned)statb.st_size)) == NULL) {
    115 		(void)fclose(fp);
    116 		return(okshells);
    117 	}
    118 	shells = (char **)calloc((unsigned)statb.st_size / 3, sizeof (char *));
    119 	if (shells == NULL) {
    120 		(void)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(*cp) && *cp != '#' && *cp != '\0')
    134 			cp++;
    135 		*cp++ = '\0';
    136 	}
    137 	*sp = (char *)0;
    138 	(void)fclose(fp);
    139 	return (shells);
    140 }
    141