release/src/router/nfs-utils/utils/mount/token.c

   1 /*
   2  * token.c -- tokenize strings, a la strtok(3)
   3  *
   4  * Copyright (C) 2007 Oracle.  All rights reserved.
   5  * Copyright (C) 2007 Chuck Lever <chuck.lever@oracle.com>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2 of the License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public
  18  * License along with this program; if not, write to the
  19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20  * Boston, MA 021110-1307, USA.
  21  *
  22  */
  23
  24 /*
  25  * We've constructed a simple string tokenizer that is better than
  26  * strtok(3) in several ways:
  27  *
  28  * 1.  It doesn't interfere with ongoing tokenizations using strtok(3).
  29  * 2.  It's re-entrant so we can nest tokenizations, if needed.
  30  * 3.  It can handle double-quoted delimiters (needed for 'context="sd,fslj"').
  31  * 4.  It doesn't alter the string we're tokenizing, so it can work
  32  *     on write-protected strings as well as writable strings.
  33  */
  34
  35
  36 #include <ctype.h>
  37 #include <unistd.h>
  38 #include <stdio.h>
  39 #include <string.h>
  40 #include <stdlib.h>
  41 #include <errno.h>
  42
  43 #include "token.h"
  44
  45
  46 struct tokenizer_state {
  47         char *pos;
  48         char delimiter;
  49         int error;
  50 };
  51
  52 static void find_next_nondelimiter(struct tokenizer_state *tstate)
  53 {
  54         while (*tstate->pos != '\0' && *tstate->pos == tstate->delimiter)
  55                 tstate->pos++;
  56 }
  57
  58 static size_t find_next_delimiter(struct tokenizer_state *tstate)
  59 {
  60         size_t len = 0;
  61         int quote_seen = 0;
  62
  63         while (*tstate->pos != '\0') {
  64                 if (*tstate->pos == '"')
  65                         quote_seen ^= 1;
  66
  67                 if (!quote_seen && *tstate->pos == tstate->delimiter)
  68                         break;
  69
  70                 len++;
  71                 tstate->pos++;
  72         }
  73
  74         /* did the string terminate before the close quote? */
  75         if (quote_seen) {
  76                 tstate->error = EINVAL;
  77                 return 0;
  78         }
  79
  80         return len;
  81 }
  82
  83 /**
  84  * next_token - find the next token in a string and return it
  85  * @tstate: pointer to tokenizer context object
  86  *
  87  * Returns the next token found in the current string.
  88  * Returns NULL if there are no more tokens in the string,
  89  * or if an error occurs.
  90  *
  91  * Side effect: tstate is updated
  92  */
  93 char *next_token(struct tokenizer_state *tstate)
  94 {
  95         char *token;
  96         size_t len;
  97
  98         if (!tstate || !tstate->pos || tstate->error)
  99                 return NULL;
 100
 101         find_next_nondelimiter(tstate);
 102         if (*tstate->pos == '\0')
 103                 goto fail;
 104         token = tstate->pos;
 105
 106         len = find_next_delimiter(tstate);
 107         if (len) {
 108                 token = strndup(token, len);
 109                 if (token)
 110                         return token;
 111                 tstate->error = ENOMEM;
 112         }
 113
 114 fail:
 115         tstate->pos = NULL;
 116         return NULL;                    /* no tokens found in this string */
 117 }
 118
 119 /**
 120  * init_tokenizer - return an initialized tokenizer context object
 121  * @string: pointer to C string
 122  * @delimiter: single character that delimits tokens in @string
 123  *
 124  * Returns an initialized tokenizer context object
 125  */
 126 struct tokenizer_state *init_tokenizer(char *string, char delimiter)
 127 {
 128         struct tokenizer_state *tstate;
 129
 130         tstate = malloc(sizeof(*tstate));
 131         if (tstate) {
 132                 tstate->pos = string;
 133                 tstate->delimiter = delimiter;
 134                 tstate->error = 0;
 135         }
 136         return tstate;
 137 }
 138
 139 /**
 140  * tokenizer_error - digs error value out of tokenizer context
 141  * @tstate: pointer to tokenizer context object
 142  *
 143  */
 144 int tokenizer_error(struct tokenizer_state *tstate)
 145 {
 146         return tstate ? tstate->error : 0;
 147 }
 148
 149 /**
 150  * end_tokenizer - free a tokenizer context object
 151  * @tstate: pointer to tokenizer context object
 152  *
 153  */
 154 void end_tokenizer(struct tokenizer_state *tstate)
 155 {
 156         free(tstate);
 157 }