1 /* $OpenBSD: getusershell.c,v 1.17 2015/12/08 16:28:26 tedu 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 <ctype.h> 32 #include <limits.h> 33 #include <paths.h> 34 #include <stdint.h> 35 #include <stdio.h> 36 #include <stdlib.h> 37 #include <string.h> 38 #include <unistd.h> 39 40 /* 41 * Local shells should NOT be added here. They should be added in 42 * /etc/shells. 43 */ 44 45 static char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, _PATH_KSHELL, NULL }; 46 static char **curshell, **shells; 47 static char **initshells(void); 48 49 /* 50 * Get a list of shells from _PATH_SHELLS, if it exists. 51 */ 52 char * 53 getusershell(void) 54 { 55 char *ret; 56 57 if (curshell == NULL) 58 curshell = initshells(); 59 ret = *curshell; 60 if (ret != NULL) 61 curshell++; 62 return (ret); 63 } 64 65 void 66 endusershell(void) 67 { 68 char **s; 69 70 if ((s = shells)) 71 while (*s) 72 free(*s++); 73 free(shells); 74 shells = NULL; 75 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 size_t nshells, nalloc, linesize; 90 char *line; 91 FILE *fp; 92 93 free(shells); 94 shells = NULL; 95 96 if ((fp = fopen(_PATH_SHELLS, "re")) == NULL) 97 return (okshells); 98 99 line = NULL; 100 nalloc = 10; // just an initial guess 101 nshells = 0; 102 shells = reallocarray(NULL, nalloc, sizeof (char *)); 103 if (shells == NULL) 104 goto fail; 105 linesize = 0; 106 while (getline(&line, &linesize, fp) != -1) { 107 if (*line != '/') 108 continue; 109 line[strcspn(line, "#\n")] = '\0'; 110 if (!(shells[nshells] = strdup(line))) 111 goto fail; 112 113 if (nshells + 1 == nalloc) { 114 char **new = reallocarray(shells, nalloc * 2, sizeof(char *)); 115 if (!new) 116 goto fail; 117 shells = new; 118 nalloc *= 2; 119 } 120 nshells++; 121 } 122 free(line); 123 shells[nshells] = NULL; 124 (void)fclose(fp); 125 return (shells); 126 127 fail: 128 free(line); 129 while (nshells) 130 free(shells[nshells--]); 131 free(shells); 132 shells = NULL; 133 (void)fclose(fp); 134 return (okshells); 135 } 136