On 07/25/2013 12:47 PM, Joe Perches wrote:
On Thu, 2013-07-25 at 21:02 +0800, Du, Changbin wrote:
From: "Du, Changbin" <changbin...@gmail.com>
This patch add wildcard '*'(matches zero or more characters) and '?'
(matches one character) support when qurying debug flags.
Seems very useful. Caveat below.
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
[]
@@ -127,6 +127,21 @@ static void vpr_info_dq(const struct ddebug_query *query,
const char *msg)
query->first_lineno, query->last_lineno);
}
+static int match_pattern(char *pat, char *str)
+{
+ switch (*pat) {
+ case '\0':
+ return !*str;
+ case '*':
+ return match_pattern(pat+1, str) ||
+ (*str && match_pattern(pat, str+1));
+ case '?':
+ return *str && match_pattern(pat+1, str+1);
+ default:
+ return *pat == *str && match_pattern(pat+1, str 1);
+ }
+}
What's the maximum length string used today?
On a very long pattern, can this recursion cause stack overflow?
Other than that, I like it.
The recursion here is a concern - especially since the 'pat' pointer is
controlled from userspace. Maybe not at pretty, but this can easily be
done in userspace. For example, to set all driver/usb* one could do
something like:
grep "drivers/usb" control | awk -F ":| " '{ print "file " $1 " line "
$2 }' | xargs -i -n1 echo {} +p > control
Thanks,
-Jason
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