mount.nfs: add new string tokenizer facility

[nfs-utils.git] / utils / mount / token.c

diff --git a/utils/mount/token.c b/utils/mount/token.c
new file mode 100644 (file)
index 0000000..5ef9604
--- /dev/null
+++ b/utils/mount/token.c
@@ -0,0 +1,157 @@
+/*
+ * token.c -- tokenize strings, a la strtok(3)
+ *
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ * Copyright (C) 2007 Chuck Lever <chuck.lever@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ */
+
+/*
+ * We've constructed a simple string tokenizer that is better than
+ * strtok(3) in several ways:
+ *
+ * 1.  It doesn't interfere with ongoing tokenizations using strtok(3).
+ * 2.  It's re-entrant so we can nest tokenizations, if needed.
+ * 3.  It can handle double-quoted delimiters (needed for 'context="sd,fslj"').
+ * 4.  It doesn't alter the string we're tokenizing, so it can work
+ *     on write-protected strings as well as writable strings.
+ */
+
+
+#include <ctype.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include "token.h"
+
+
+struct tokenizer_state {
+       char *pos;
+       char delimiter;
+       int error;
+};
+
+static void find_next_nondelimiter(struct tokenizer_state *tstate)
+{
+       while (*tstate->pos != '\0' && *tstate->pos == tstate->delimiter)
+               tstate->pos++;
+}
+
+static size_t find_next_delimiter(struct tokenizer_state *tstate)
+{
+       size_t len = 0;
+       int quote_seen = 0;
+
+       while (*tstate->pos != '\0') {
+               if (*tstate->pos == '"')
+                       quote_seen ^= 1;
+
+               if (!quote_seen && *tstate->pos == tstate->delimiter)
+                       break;
+
+               len++;
+               tstate->pos++;
+       }
+
+       /* did the string terminate before the close quote? */
+       if (quote_seen) {
+               tstate->error = EINVAL;
+               return 0;
+       }
+
+       return len;
+}
+
+/**
+ * next_token - find the next token in a string and return it
+ * @tstate: pointer to tokenizer context object
+ *
+ * Returns the next token found in the current string.
+ * Returns NULL if there are no more tokens in the string,
+ * or if an error occurs.
+ *
+ * Side effect: tstate is updated
+ */
+char *next_token(struct tokenizer_state *tstate)
+{
+       char *token;
+       size_t len;
+
+       if (!tstate || !tstate->pos || tstate->error)
+               return NULL;
+
+       find_next_nondelimiter(tstate);
+       if (*tstate->pos == '\0')
+               goto fail;
+       token = tstate->pos;
+
+       len = find_next_delimiter(tstate);
+       if (len) {
+               token = strndup(token, len);
+               if (token)
+                       return token;
+               tstate->error = ENOMEM;
+       }
+
+fail:
+       tstate->pos = NULL;
+       return NULL;                    /* no tokens found in this string */
+}
+
+/**
+ * init_tokenizer - return an initialized tokenizer context object
+ * @string: pointer to C string
+ * @delimiter: single character that delimits tokens in @string
+ *
+ * Returns an initialized tokenizer context object
+ */
+struct tokenizer_state *init_tokenizer(char *string, char delimiter)
+{
+       struct tokenizer_state *tstate;
+
+       tstate = malloc(sizeof(*tstate));
+       if (tstate) {
+               tstate->pos = string;
+               tstate->delimiter = delimiter;
+               tstate->error = 0;
+       }
+       return tstate;
+}
+
+/**
+ * tokenizer_error - digs error value out of tokenizer context
+ * @tstate: pointer to tokenizer context object
+ *
+ */
+int tokenizer_error(struct tokenizer_state *tstate)
+{
+       return tstate ? tstate->error : 0;
+}
+
+/**
+ * end_tokenizer - free a tokenizer context object
+ * @tstate: pointer to tokenizer context object
+ *
+ */
+void end_tokenizer(struct tokenizer_state *tstate)
+{
+       free(tstate);
+}