1 files changed, 220 insertions, 0 deletions
diff --git a/lib/parser.c b/lib/parser.c
new file mode 100644
index 0000000..7ad2a48
--- /dev/null
+++ b/lib/parser.c
@@ -0,0 +1,220 @@
+/*
+ * lib/parser.c - simple parser for mount, etc. options.
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2.  See the file COPYING for more details.
+ */
+
+#include <linux/ctype.h>
+#include <linux/module.h>
+#include <linux/parser.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+/**
+ * match_one: - Determines if a string matches a simple pattern
+ * @s: the string to examine for presense of the pattern
+ * @p: the string containing the pattern
+ * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
+ * locations.
+ *
+ * Description: Determines if the pattern @p is present in string @s. Can only
+ * match extremely simple token=arg style patterns. If the pattern is found,
+ * the location(s) of the arguments will be returned in the @args array.
+ */
+static int match_one(char *s, char *p, substring_t args[])
+{
+	char *meta;
+	int argc = 0;
+
+	if (!p)
+		return 1;
+
+	while(1) {
+		int len = -1;
+		meta = strchr(p, '%');
+		if (!meta)
+			return strcmp(p, s) == 0;
+
+		if (strncmp(p, s, meta-p))
+			return 0;
+
+		s += meta - p;
+		p = meta + 1;
+
+		if (isdigit(*p))
+			len = simple_strtoul(p, &p, 10);
+		else if (*p == '%') {
+			if (*s++ != '%')
+				return 0;
+			p++;
+			continue;
+		}
+
+		if (argc >= MAX_OPT_ARGS)
+			return 0;
+
+		args[argc].from = s;
+		switch (*p++) {
+		case 's':
+			if (strlen(s) == 0)
+				return 0;
+			else if (len == -1 || len > strlen(s))
+				len = strlen(s);
+			args[argc].to = s + len;
+			break;
+		case 'd':
+			simple_strtol(s, &args[argc].to, 0);
+			goto num;
+		case 'u':
+			simple_strtoul(s, &args[argc].to, 0);
+			goto num;
+		case 'o':
+			simple_strtoul(s, &args[argc].to, 8);
+			goto num;
+		case 'x':
+			simple_strtoul(s, &args[argc].to, 16);
+		num:
+			if (args[argc].to == args[argc].from)
+				return 0;
+			break;
+		default:
+			return 0;
+		}
+		s = args[argc].to;
+		argc++;
+	}
+}
+
+/**
+ * match_token: - Find a token (and optional args) in a string
+ * @s: the string to examine for token/argument pairs
+ * @table: match_table_t describing the set of allowed option tokens and the
+ * arguments that may be associated with them. Must be terminated with a
+ * &struct match_token whose pattern is set to the NULL pointer.
+ * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
+ * locations.
+ *
+ * Description: Detects which if any of a set of token strings has been passed
+ * to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style
+ * format identifiers which will be taken into account when matching the
+ * tokens, and whose locations will be returned in the @args array.
+ */
+int match_token(char *s, match_table_t table, substring_t args[])
+{
+	struct match_token *p;
+
+	for (p = table; !match_one(s, p->pattern, args) ; p++)
+		;
+
+	return p->token;
+}
+
+/**
+ * match_number: scan a number in the given base from a substring_t
+ * @s: substring to be scanned
+ * @result: resulting integer on success
+ * @base: base to use when converting string
+ *
+ * Description: Given a &substring_t and a base, attempts to parse the substring
+ * as a number in that base. On success, sets @result to the integer represented
+ * by the string and returns 0. Returns either -ENOMEM or -EINVAL on failure.
+ */
+static int match_number(substring_t *s, int *result, int base)
+{
+	char *endp;
+	char *buf;
+	int ret;
+
+	buf = kmalloc(s->to - s->from + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	memcpy(buf, s->from, s->to - s->from);
+	buf[s->to - s->from] = '\0';
+	*result = simple_strtol(buf, &endp, base);
+	ret = 0;
+	if (endp == buf)
+		ret = -EINVAL;
+	kfree(buf);
+	return ret;
+}
+
+/**
+ * match_int: - scan a decimal representation of an integer from a substring_t
+ * @s: substring_t to be scanned
+ * @result: resulting integer on success
+ *
+ * Description: Attempts to parse the &substring_t @s as a decimal integer. On
+ * success, sets @result to the integer represented by the string and returns 0.
+ * Returns either -ENOMEM or -EINVAL on failure.
+ */
+int match_int(substring_t *s, int *result)
+{
+	return match_number(s, result, 0);
+}
+
+/**
+ * match_octal: - scan an octal representation of an integer from a substring_t
+ * @s: substring_t to be scanned
+ * @result: resulting integer on success
+ *
+ * Description: Attempts to parse the &substring_t @s as an octal integer. On
+ * success, sets @result to the integer represented by the string and returns
+ * 0. Returns either -ENOMEM or -EINVAL on failure.
+ */
+int match_octal(substring_t *s, int *result)
+{
+	return match_number(s, result, 8);
+}
+
+/**
+ * match_hex: - scan a hex representation of an integer from a substring_t
+ * @s: substring_t to be scanned
+ * @result: resulting integer on success
+ *
+ * Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
+ * On success, sets @result to the integer represented by the string and
+ * returns 0. Returns either -ENOMEM or -EINVAL on failure.
+ */
+int match_hex(substring_t *s, int *result)
+{
+	return match_number(s, result, 16);
+}
+
+/**
+ * match_strcpy: - copies the characters from a substring_t to a string
+ * @to: string to copy characters to.
+ * @s: &substring_t to copy
+ *
+ * Description: Copies the set of characters represented by the given
+ * &substring_t @s to the c-style string @to. Caller guarantees that @to is
+ * large enough to hold the characters of @s.
+ */
+void match_strcpy(char *to, substring_t *s)
+{
+	memcpy(to, s->from, s->to - s->from);
+	to[s->to - s->from] = '\0';
+}
+
+/**
+ * match_strdup: - allocate a new string with the contents of a substring_t
+ * @s: &substring_t to copy
+ *
+ * Description: Allocates and returns a string filled with the contents of
+ * the &substring_t @s. The caller is responsible for freeing the returned
+ * string with kfree().
+ */
+char *match_strdup(substring_t *s)
+{
+	char *p = kmalloc(s->to - s->from + 1, GFP_KERNEL);
+	if (p)
+		match_strcpy(p, s);
+	return p;
+}
+
+EXPORT_SYMBOL(match_token);
+EXPORT_SYMBOL(match_int);
+EXPORT_SYMBOL(match_octal);
+EXPORT_SYMBOL(match_hex);
+EXPORT_SYMBOL(match_strcpy);
+EXPORT_SYMBOL(match_strdup);