lws_strcmp_wildcard

Add helper to do a strcmp() but against the first argument that may
contain zero or more * wildcards

include/libwebsockets/lws-tokenize.h

@@ -251,3 +251,15 @@ LWS_VISIBLE LWS_EXTERN int
 lws_strexp_expand(lws_strexp_t *exp, const char *in, size_t len,
 		  size_t *pused_in, size_t *pused_out);
 
+/**
+ * lws_strcmp_wildcard() - strcmp but the first arg can have wildcards
+ *
+ * \p wildcard: a string that may contain zero to three *, and may lack a NUL
+ * \p len: length of the wildcard string
+ * \p check: string to test to see if it matches wildcard
+ *
+ * Exactly like strcmp, but supports patterns like "a*", "a*b", "a*b*" etc
+ * where a and b are arbitrary substrings
+ */
+LWS_VISIBLE LWS_EXTERN int
+lws_strcmp_wildcard(const char *wildcard, size_t len, const char *check);

lib/core/libwebsockets.c

@@ -1135,6 +1135,82 @@ drain:
 	return LSTRX_DONE;
 }
 
+int
+lws_strcmp_wildcard(const char *wildcard, size_t len, const char *check)
+{
+	const char *match[3], *wc[3], *wc_end = wildcard + len;
+	int sp = 0;
+
+	do {
+
+		if (wildcard == wc_end) {
+			/*
+			 * We reached the end of wildcard, but not of check,
+			 * and the last thing in wildcard was not a * or we
+			 * would have completed already... if we can rewind,
+			 * let's try that...
+			 */
+			if (sp) {
+				wildcard = wc[sp - 1];
+				check = match[--sp];
+
+				continue;
+			}
+
+			/* otherwise it's the end of the road for this one */
+
+			return 1;
+		}
+
+		if (*wildcard == '*') {
+
+			if (++wildcard == wc_end)
+				 /*
+				  * Wildcard ended on a *, so we know we will
+				  * match unconditionally
+				  */
+				return 0;
+
+			/*
+			 * Now we need to stick wildcard here and see if there
+			 * is any remaining match exists, for eg b of "a*b"
+			 */
+
+			if (sp == LWS_ARRAY_SIZE(match)) {
+				lwsl_err("%s: exceeds * stack\n", __func__);
+				return 1; /* we can't deal with it */
+			}
+
+			wc[sp] = wildcard;
+			/* if we ever pop and come back here, pick up from +1 */
+			match[sp++] = check + 1;
+			continue;
+		}
+
+		if (*(check++) == *wildcard) {
+
+			if (wildcard == wc_end)
+				return 0;
+			/*
+			 * We're still compatible with wildcard... keep going
+			 */
+			wildcard++;
+
+			continue;
+		}
+
+		if (!sp)
+			/*
+			 * We're just trying to match literals, and failed...
+			 */
+			return 1;
+
+		/* we're looking for a post-* match... keep looking... */
+
+	} while (*check);
+
+	return !!*wildcard;
+}
 
 #if LWS_MAX_SMP > 1
 

minimal-examples/api-tests/api-test-lws_tokenize/main.c

@@ -660,6 +660,67 @@ int main(int argc, const char **argv)
 		}
 	}
 
+	if (lws_strcmp_wildcard("allied", 6, "allied")) {
+		lwsl_user("%s: wc 1 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("a*", 2, "allied")) {
+		lwsl_user("%s: wc 2 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("all*", 4, "allied")) {
+		lwsl_user("%s: wc 3 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("all*d", 5, "allied")) {
+		lwsl_user("%s: wc 4 fail\n", __func__);
+		fail++;
+	}
+	if (!lws_strcmp_wildcard("b*", 2, "allied")) {
+		lwsl_user("%s: wc 5 fail\n", __func__);
+		fail++;
+	}
+	if (!lws_strcmp_wildcard("b*ed", 4, "allied")) {
+		lwsl_user("%s: wc 6 fail\n", __func__);
+		fail++;
+	}
+	if (!lws_strcmp_wildcard("allie", 5, "allied")) {
+		lwsl_user("%s: wc 7 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("allie*", 6, "allied")) {
+		lwsl_user("%s: wc 8 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("*llie*", 6, "allied")) {
+		lwsl_user("%s: wc 9 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("*llied", 6, "allied")) {
+		lwsl_user("%s: wc 10 fail\n", __func__);
+		fail++;
+	}
+	if (!lws_strcmp_wildcard("*llie", 5, "allied")) {
+		lwsl_user("%s: wc 11 fail\n", __func__);
+		fail++;
+	}
+	if (!lws_strcmp_wildcard("*nope", 5, "allied")) {
+		lwsl_user("%s: wc 12 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("*li*", 4, "allied")) {
+		lwsl_user("%s: wc 13 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("*", 1, "allied")) {
+		lwsl_user("%s: wc 14 fail\n", __func__);
+		fail++;
+	}
+	if (lws_strcmp_wildcard("*abc*d", 6, "xxabyyabcdd")) {
+		lwsl_user("%s: wc 15 fail\n", __func__);
+		fail++;
+	}
+
 	lwsl_user("Completed: PASS: %d, FAIL: %d\n", ok, fail);
 
 	return !(ok && !fail);