usr/src/common/util/getresponse.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 #include <stdio.h>
  27 #include <string.h>
  28 #include <stdlib.h>
  29 #include <regex.h>
  30 #include <locale.h>
  31 #include <langinfo.h>
  32 #include <limits.h>
  33 #include <errno.h>
  34 #include "getresponse.h"
  35
  36 /* defaults - C locale values for yesstr, nostr, yesexpr (LC_MESSAGES) */
  37 #define DEFAULT_YESSTR  "yes"
  38 #define DEFAULT_NOSTR   "no"
  39 #define DEFAULT_YESEXPR "^[yY]"
  40 #define DEFAULT_NOEXPR  "^[nN]"
  41
  42 #define FREE_MEM        \
  43         if (yesstr)     \
  44                 free(yesstr);   \
  45         if (nostr)      \
  46                 free(nostr);    \
  47         if (yesexpr)    \
  48                 free(yesexpr);  \
  49         if (noexpr)     \
  50                 free(noexpr)
  51
  52 #define SET_DEFAULT_STRS \
  53         yesstr = DEFAULT_YESSTR; \
  54         nostr = DEFAULT_NOSTR; \
  55         yesexpr = DEFAULT_YESEXPR; \
  56         noexpr = DEFAULT_NOEXPR;
  57
  58 /* variables used by getresponse functions */
  59 char    *yesstr = NULL;
  60 char    *nostr = NULL;
  61
  62 /* for regcomp()/regexec() yesexpr and noexpr */
  63 static regex_t preg_yes, preg_no;
  64
  65 /*
  66  * This function compiles a regular expression that is used to match an
  67  * affirmative response from the user, and also assigns the strings used
  68  * in the prompts that request affirmative or negative responses.  The
  69  * locale's values for YESEXPR, NOEXPR, YESSTR and NOSTR are used.
  70  *
  71  * If there are any problems using the locale's YESEXPR, NOEXPR, YESSTR or NOSTR
  72  * values, default values of YESEXPR, YESSTR and NOSTR will be used
  73  * as a fallback.  The default values are the same as the C locale values.
  74  */
  75 int
  76 init_yes(void)
  77 {
  78         int     fallback = 0;
  79         char    *yesexpr;
  80         char    *noexpr;
  81
  82         /* get yes expression and strings for yes/no prompts */
  83         yesstr  = strdup(nl_langinfo(YESSTR));
  84         nostr   = strdup(nl_langinfo(NOSTR));
  85         yesexpr = strdup(nl_langinfo(YESEXPR));
  86         noexpr  = strdup(nl_langinfo(NOEXPR));
  87
  88         if (yesstr == NULL || nostr == NULL ||
  89             yesexpr == NULL || noexpr == NULL) {
  90                 FREE_MEM;
  91                 errno = ENOMEM;
  92                 return (-1);
  93         }
  94
  95         /* if problem with locale strings, use default values */
  96         if (*yesstr == '\0' || *nostr == '\0' ||
  97             *yesexpr == '\0' || *noexpr == '\0') {
  98                 FREE_MEM;
  99                 SET_DEFAULT_STRS;
 100                 fallback = 1;
 101         }
 102         /* Compile the yes and no expressions */
 103         while (regcomp(&preg_yes, yesexpr, REG_EXTENDED | REG_NOSUB) != 0 ||
 104             regcomp(&preg_no, noexpr, REG_EXTENDED | REG_NOSUB) != 0) {
 105                 if (fallback == 1) {
 106                         /* The fallback yesexpr failed, so exit */
 107                         errno = EINVAL;
 108                         return (-1);
 109                 }
 110                 /* The locale's yesexpr or noexpr failed so use fallback */
 111                 FREE_MEM;
 112                 SET_DEFAULT_STRS;
 113                 fallback = 1;
 114         }
 115         return (0);
 116 }
 117
 118 static int
 119 yes_no(int (*func)(char *))
 120 {
 121         int     i, b;
 122         char    ans[LINE_MAX + 1];
 123
 124         /* Get user's answer */
 125         i = 0;
 126         for (;;) {
 127                 b = getchar();
 128                 if (b == '\n' || b == '\0' || b == EOF)
 129                         break;
 130                 if (i < LINE_MAX)
 131                         ans[i] = b;
 132                 i++;
 133         }
 134         if (i >= LINE_MAX)
 135                 ans[LINE_MAX] = '\0';
 136         else
 137                 ans[i] = '\0';
 138
 139         return (func(ans));
 140 }
 141
 142 static int
 143 yes_no_check(char *ans, regex_t *reg1, regex_t *reg2)
 144 {
 145         if (regexec(reg1, ans, 0, NULL, 0) == 0) {
 146                 if (regexec(reg2, ans, 0, NULL, 0) == 0) {
 147                         /* Both Expressions Match (reg2 conservative) */
 148                         return (0);
 149                 }
 150                 /* Match */
 151                 return (1);
 152         }
 153         return (0);
 154 }
 155
 156 /*
 157  * yes_check() returns 1 if the input string is matched by yesexpr and is
 158  * not matched by noexpr;  otherwise yes_check() returns 0.
 159  */
 160 int
 161 yes_check(char *ans)
 162 {
 163         return (yes_no_check(ans, &preg_yes, &preg_no));
 164 }
 165
 166 /*
 167  * no_check() returns 1 if the input string is matched by noexpr and is
 168  * not matched by yesexpr;  otherwise no_check() returns 0.
 169  */
 170 int
 171 no_check(char *ans)
 172 {
 173         return (yes_no_check(ans, &preg_no, &preg_yes));
 174 }
 175
 176 int
 177 yes(void)
 178 {
 179         return (yes_no(yes_check));
 180 }
 181
 182 int
 183 no(void)
 184 {
 185         return (yes_no(no_check));
 186 }