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 yesexpr/noexpr (LC_MESSAGES) */
  37 #define DEFAULT_YESEXPR "^[yY]"
  38 #define DEFAULT_NOEXPR  "^[nN]"
  39
  40 #define FREE_MEM        \
  41         free(yesexpr);  \
  42         free(noexpr)
  43
  44 #define SET_DEFAULT_STRS \
  45         yesexpr = DEFAULT_YESEXPR; \
  46         noexpr = DEFAULT_NOEXPR;
  47
  48 /* for regcomp()/regexec() yesexpr and noexpr */
  49 static regex_t preg_yes, preg_no;
  50
  51 /*
  52  * This function compiles a regular expression that is used to match an
  53  * affirmative response from the user, and also assigns the strings used
  54  * in the prompts that request affirmative or negative responses.  The
  55  * locale's values for YESEXPR, NOEXPR, YESSTR and NOSTR are used.
  56  *
  57  * If there are any problems using the locale's YESEXPR, NOEXPR, YESSTR or NOSTR
  58  * values, default values of YESEXPR, YESSTR and NOSTR will be used
  59  * as a fallback.  The default values are the same as the C locale values.
  60  */
  61 int
  62 init_yes(void)
  63 {
  64         int     fallback = 0;
  65         char    *yesexpr;
  66         char    *noexpr;
  67
  68         yesexpr = strdup(nl_langinfo(YESEXPR));
  69         noexpr  = strdup(nl_langinfo(NOEXPR));
  70
  71         if (yesexpr == NULL || noexpr == NULL) {
  72                 FREE_MEM;
  73                 errno = ENOMEM;
  74                 return (-1);
  75         }
  76
  77         /* if problem with locale strings, use default values */
  78         if (*yesexpr == '\0' || *noexpr == '\0') {
  79                 FREE_MEM;
  80                 SET_DEFAULT_STRS;
  81                 fallback = 1;
  82         }
  83         /* Compile the yes and no expressions */
  84         while (regcomp(&preg_yes, yesexpr, REG_EXTENDED | REG_NOSUB) != 0 ||
  85             regcomp(&preg_no, noexpr, REG_EXTENDED | REG_NOSUB) != 0) {
  86                 if (fallback == 1) {
  87                         /* The fallback yesexpr failed, so exit */
  88                         errno = EINVAL;
  89                         return (-1);
  90                 }
  91                 /* The locale's yesexpr or noexpr failed so use fallback */
  92                 FREE_MEM;
  93                 SET_DEFAULT_STRS;
  94                 fallback = 1;
  95         }
  96         return (0);
  97 }
  98
  99 static int
 100 yes_no(int (*func)(char *))
 101 {
 102         int     i, b;
 103         char    ans[LINE_MAX + 1];
 104
 105         /* Get user's answer */
 106         i = 0;
 107         for (;;) {
 108                 b = getchar();
 109                 if (b == '\n' || b == '\0' || b == EOF)
 110                         break;
 111                 if (i < LINE_MAX)
 112                         ans[i] = b;
 113                 i++;
 114         }
 115         if (i >= LINE_MAX)
 116                 ans[LINE_MAX] = '\0';
 117         else
 118                 ans[i] = '\0';
 119
 120         return (func(ans));
 121 }
 122
 123 static int
 124 yes_no_check(char *ans, regex_t *reg1, regex_t *reg2)
 125 {
 126         if (regexec(reg1, ans, 0, NULL, 0) == 0) {
 127                 if (regexec(reg2, ans, 0, NULL, 0) == 0) {
 128                         /* Both Expressions Match (reg2 conservative) */
 129                         return (0);
 130                 }
 131                 /* Match */
 132                 return (1);
 133         }
 134         return (0);
 135 }
 136
 137 /*
 138  * yes_check() returns 1 if the input string is matched by yesexpr and is
 139  * not matched by noexpr;  otherwise yes_check() returns 0.
 140  */
 141 int
 142 yes_check(char *ans)
 143 {
 144         return (yes_no_check(ans, &preg_yes, &preg_no));
 145 }
 146
 147 /*
 148  * no_check() returns 1 if the input string is matched by noexpr and is
 149  * not matched by yesexpr;  otherwise no_check() returns 0.
 150  */
 151 int
 152 no_check(char *ans)
 153 {
 154         return (yes_no_check(ans, &preg_no, &preg_yes));
 155 }
 156
 157 int
 158 yes(void)
 159 {
 160         return (yes_no(yes_check));
 161 }
 162
 163 int
 164 no(void)
 165 {
 166         return (yes_no(no_check));
 167 }