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getusershell.c revision 1.1 
      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[] = "@(#)getusershell.c	5.7 (Berkeley) 2/23/91";
     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 <ctype.h>
     42 #include <stdio.h>
     43 #include <stdlib.h>
     44 #include <unistd.h>
     45 
     46 #define SHELLS "/etc/shells"
     47 
     48 /*
     49  * Do not add local shells here.  They should be added in /etc/shells
     50  */
     51 static char *okshells[] =
     52     { "/bin/sh", "/bin/csh", 0 };
     53 
     54 static char **shells, *strings;
     55 static char **curshell = NULL;
     56 extern char **initshells();
     57 
     58 /*
     59  * Get a list of shells from SHELLS, if it exists.
     60  */
     61 char *
     62 getusershell()
     63 {
     64 	char *ret;
     65 
     66 	if (curshell == NULL)
     67 		curshell = initshells();
     68 	ret = *curshell;
     69 	if (ret != NULL)
     70 		curshell++;
     71 	return (ret);
     72 }
     73 
     74 void
     75 endusershell()
     76 {
     77 
     78 	if (shells != NULL)
     79 		free((char *)shells);
     80 	shells = NULL;
     81 	if (strings != NULL)
     82 		free(strings);
     83 	strings = NULL;
     84 	curshell = NULL;
     85 }
     86 
     87 void
     88 setusershell()
     89 {
     90 
     91 	curshell = initshells();
     92 }
     93 
     94 static char **
     95 initshells()
     96 {
     97 	register char **sp, *cp;
     98 	register FILE *fp;
     99 	struct stat statb;
    100 
    101 	if (shells != NULL)
    102 		free((char *)shells);
    103 	shells = NULL;
    104 	if (strings != NULL)
    105 		free(strings);
    106 	strings = NULL;
    107 	if ((fp = fopen(SHELLS, "r")) == (FILE *)0)
    108 		return(okshells);
    109 	if (fstat(fileno(fp), &statb) == -1) {
    110 		(void)fclose(fp);
    111 		return(okshells);
    112 	}
    113 	if ((strings = malloc((unsigned)statb.st_size)) == NULL) {
    114 		(void)fclose(fp);
    115 		return(okshells);
    116 	}
    117 	shells = (char **)calloc((unsigned)statb.st_size / 3, sizeof (char *));
    118 	if (shells == NULL) {
    119 		(void)fclose(fp);
    120 		free(strings);
    121 		strings = NULL;
    122 		return(okshells);
    123 	}
    124 	sp = shells;
    125 	cp = strings;
    126 	while (fgets(cp, MAXPATHLEN + 1, fp) != NULL) {
    127 		while (*cp != '#' && *cp != '/' && *cp != '\0')
    128 			cp++;
    129 		if (*cp == '#' || *cp == '\0')
    130 			continue;
    131 		*sp++ = cp;
    132 		while (!isspace(*cp) && *cp != '#' && *cp != '\0')
    133 			cp++;
    134 		*cp++ = '\0';
    135 	}
    136 	*sp = (char *)0;
    137 	(void)fclose(fp);
    138 	return (shells);
    139 }
    140