1 /* $OpenBSD: getusershell.c,v 1.15 2015/02/06 23:21:58 millert Exp $ */ 2 /* 3 * Copyright (c) 1985, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/stat.h> 32 33 #include <ctype.h> 34 #include <limits.h> 35 #include <paths.h> 36 #include <stdint.h> 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <unistd.h> 40 41 /* 42 * Local shells should NOT be added here. They should be added in 43 * /etc/shells. 44 */ 45 46 static char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, _PATH_KSHELL, NULL }; 47 static char **curshell, **shells, *strings; 48 static char **initshells(void); 49 50 /* 51 * Get a list of shells from _PATH_SHELLS, if it exists. 52 */ 53 char * 54 getusershell(void) 55 { 56 char *ret; 57 58 if (curshell == NULL) 59 curshell = initshells(); 60 ret = *curshell; 61 if (ret != NULL) 62 curshell++; 63 return (ret); 64 } 65 66 void 67 endusershell(void) 68 { 69 70 if (shells != NULL) 71 free(shells); 72 shells = NULL; 73 if (strings != NULL) 74 free(strings); 75 strings = NULL; 76 curshell = NULL; 77 } 78 79 void 80 setusershell(void) 81 { 82 83 curshell = initshells(); 84 } 85 86 static char ** 87 initshells(void) 88 { 89 char **sp, *cp; 90 FILE *fp; 91 struct stat statb; 92 93 if (shells != NULL) 94 free(shells); 95 shells = NULL; 96 if (strings != NULL) 97 free(strings); 98 strings = NULL; 99 if ((fp = fopen(_PATH_SHELLS, "re")) == NULL) 100 return (okshells); 101 if (fstat(fileno(fp), &statb) == -1) { 102 (void)fclose(fp); 103 return (okshells); 104 } 105 if (statb.st_size > SIZE_MAX) { 106 (void)fclose(fp); 107 return (okshells); 108 } 109 if ((strings = malloc((size_t)statb.st_size)) == NULL) { 110 (void)fclose(fp); 111 return (okshells); 112 } 113 shells = calloc((size_t)(statb.st_size / 3 + 2), sizeof (char *)); 114 if (shells == NULL) { 115 (void)fclose(fp); 116 free(strings); 117 strings = NULL; 118 return (okshells); 119 } 120 sp = shells; 121 cp = strings; 122 while (fgets(cp, PATH_MAX + 1, fp) != NULL) { 123 while (*cp != '#' && *cp != '/' && *cp != '\0') 124 cp++; 125 if (*cp == '#' || *cp == '\0') 126 continue; 127 *sp++ = cp; 128 while (!isspace((unsigned char)*cp) && *cp != '#' && *cp != '\0') 129 cp++; 130 *cp++ = '\0'; 131 } 132 *sp = NULL; 133 (void)fclose(fp); 134 return (shells); 135 } 136