X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fjson_escape%2Fjson_escape.c;h=ed4bfab944504a48db7c9e1b4cdd2825d8863bf2;hp=d344940de0a5d934da693b959857326da194fb55;hb=3ceb24bf19adbe59bf8aeda9cc1426b4ba2244c2;hpb=45f9ce170fe09bca014d874ffaa13b900c8285ba

diff --git a/ccan/json_escape/json_escape.c b/ccan/json_escape/json_escape.c
index d344940d..ed4bfab9 100644
--- a/ccan/json_escape/json_escape.c
+++ b/ccan/json_escape/json_escape.c
@@ -19,6 +19,18 @@ bool json_escape_eq(const struct json_escape *a, const struct json_escape *b)
 	return streq(a->s, b->s);
 }
 
+bool json_escape_needed(const char *str, size_t len)
+{
+	for (size_t i = 0; i < len; i++) {
+		if ((unsigned)str[i] < ' '
+		    || str[i] == 127
+		    || str[i] == '"'
+		    || str[i] == '\\')
+			return true;
+	}
+	return false;
+}
+
 static struct json_escape *escape(const tal_t *ctx,
 				  const char *str TAKES,
 				  size_t len,
@@ -27,6 +39,16 @@ static struct json_escape *escape(const tal_t *ctx,
 	struct json_escape *esc;
 	size_t i, n;
 
+	/* Fast path: can steal, and nothing to escape. */
+	if (is_taken(str)
+	    && tal_count(str) > len
+	    && !json_escape_needed(str, len)) {
+		taken(str);
+		esc = (struct json_escape *)tal_steal(ctx, str);
+		esc->s[len] = '\0';
+		return esc;
+	}
+
 	/* Worst case: all \uXXXX */
 	esc = (struct json_escape *)tal_arr(ctx, char, len * 6 + 1);