lib/parser.c: add match_wildcard() function

match_wildcard function is a simple implementation of wildcard
matching algorithm. It only supports two usual wildcardes:
    '*' - matches zero or more characters
    '?' - matches one character
This algorithm is safe since it is non-recursive.

Signed-off-by: Du, Changbin <changbin.du@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 52 insertions, 0 deletions

diff --git a/include/linux/parser.h b/include/linux/parser.h
index ea2281e726f6..39d5b7955b23 100644
--- a/include/linux/parser.h
+++ b/include/linux/parser.h
@@ -29,5 +29,6 @@ int match_token(char *, const match_table_t table, substring_t args[]);
 int match_int(substring_t *, int *result);
 int match_octal(substring_t *, int *result);
 int match_hex(substring_t *, int *result);
+bool match_wildcard(const char *pattern, const char *str);
 size_t match_strlcpy(char *, const substring_t *, size_t);
 char *match_strdup(const substring_t *);
diff --git a/lib/parser.c b/lib/parser.c
index 807b2aaa33fa..ee5295541cea 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -193,6 +193,56 @@ int match_hex(substring_t *s, int *result)
 }
 
 /**
+ * match_wildcard: - parse if a string matches given wildcard pattern
+ * @pattern: wildcard pattern
+ * @str: the string to be parsed
+ *
+ * Description: Parse the string @str to check if matches wildcard
+ * pattern @pattern. The pattern may contain two type wildcardes:
+ *   '*' - matches zero or more characters
+ *   '?' - matches one character
+ * If it's matched, return true, else return false.
+ */
+bool match_wildcard(const char *pattern, const char *str)
+{
+        const char *s = str;
+        const char *p = pattern;
+        bool star = false;
+
+        while (*s) {
+                switch (*p) {
+                case '?':
+                        s++;
+                        p++;
+                        break;
+                case '*':
+                        star = true;
+                        str = s;
+                        if (!*++p)
+                                return true;
+                        pattern = p;
+                        break;
+                default:
+                        if (*s == *p) {
+                                s++;
+                                p++;
+                        } else {
+                                if (!star)
+                                        return false;
+                                str++;
+                                s = str;
+                                p = pattern;
+                        }
+                        break;
+                }
+        }
+
+        if (*p == '*')
+                ++p;
+        return !*p;
+}
+
+/**
  * match_strlcpy: - Copy the characters from a substring_t to a sized buffer
  * @dest: where to copy to
  * @src: &substring_t to copy
@@ -235,5 +285,6 @@ EXPORT_SYMBOL(match_token);
 EXPORT_SYMBOL(match_int);
 EXPORT_SYMBOL(match_octal);
 EXPORT_SYMBOL(match_hex);
+EXPORT_SYMBOL(match_wildcard);
 EXPORT_SYMBOL(match_strlcpy);
 EXPORT_SYMBOL(match_strdup);