1/* $OpenBSD: getusershell.c,v 1.18 2019/12/10 02:35:16 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 <paths.h> 32#include <stdio.h> 33#include <stdlib.h> 34#include <string.h> 35#include <unistd.h> 36 37/* 38 * Local shells should NOT be added here. They should be added in 39 * /etc/shells. 40 */ 41 42static char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, _PATH_KSHELL, NULL }; 43static char **curshell, **shells; 44static char **initshells(void); 45 46/* 47 * Get a list of shells from _PATH_SHELLS, if it exists. 48 */ 49char * 50getusershell(void) 51{ 52 char *ret; 53 54 if (curshell == NULL) 55 curshell = initshells(); 56 ret = *curshell; 57 if (ret != NULL) 58 curshell++; 59 return (ret); 60} 61 62void 63endusershell(void) 64{ 65 char **s; 66 67 if ((s = shells)) 68 while (*s) 69 free(*s++); 70 free(shells); 71 shells = NULL; 72 73 curshell = NULL; 74} 75 76void 77setusershell(void) 78{ 79 80 curshell = initshells(); 81} 82 83static char ** 84initshells(void) 85{ 86 size_t nshells, nalloc, linesize; 87 char *line; 88 FILE *fp; 89 90 free(shells); 91 shells = NULL; 92 93 if ((fp = fopen(_PATH_SHELLS, "re")) == NULL) 94 return (okshells); 95 96 line = NULL; 97 nalloc = 10; // just an initial guess 98 nshells = 0; 99 shells = reallocarray(NULL, nalloc, sizeof (char *)); 100 if (shells == NULL) 101 goto fail; 102 linesize = 0; 103 while (getline(&line, &linesize, fp) != -1) { 104 if (*line != '/') 105 continue; 106 line[strcspn(line, "#\n")] = '\0'; 107 if (!(shells[nshells] = strdup(line))) 108 goto fail; 109 110 if (nshells + 1 == nalloc) { 111 char **new = reallocarray(shells, nalloc * 2, sizeof(char *)); 112 if (!new) 113 goto fail; 114 shells = new; 115 nalloc *= 2; 116 } 117 nshells++; 118 } 119 free(line); 120 shells[nshells] = NULL; 121 (void)fclose(fp); 122 return (shells); 123 124fail: 125 free(line); 126 while (nshells) 127 free(shells[nshells--]); 128 free(shells); 129 shells = NULL; 130 (void)fclose(fp); 131 return (okshells); 132} 133