From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 19 Apr 2011 10:53:59 +0000 (+0930)
Subject: str_talloc: make strjoin much more efficient.
X-Git-Url: https://git.ozlabs.org/?p=ccan;a=commitdiff_plain;h=ed7aec77da970556c0281e2c7573bf00d1390ff1

str_talloc: make strjoin much more efficient.

Inspired by patch from Volker.
---

diff --git a/ccan/str_talloc/str_talloc.c b/ccan/str_talloc/str_talloc.c
index 3bcb1f2a..88e02ef2 100644
--- a/ccan/str_talloc/str_talloc.c
+++ b/ccan/str_talloc/str_talloc.c
@@ -38,11 +38,17 @@ char *strjoin(const void *ctx, char *strings[], const char *delim)
 {
 	unsigned int i;
 	char *ret = talloc_strdup(ctx, "");
+	size_t totlen = 0, dlen = strlen(delim);
 
 	for (i = 0; strings[i]; i++) {
-		ret = talloc_append_string(ret, strings[i]);
-		ret = talloc_append_string(ret, delim);
+		size_t len = strlen(strings[i]);
+		ret = talloc_realloc(ctx, ret, char, totlen + len + dlen + 1);
+		memcpy(ret + totlen, strings[i], len);
+		totlen += len;
+		memcpy(ret + totlen, delim, dlen);
+		totlen += dlen;
 	}
+	ret[totlen] = '\0';
 	return ret;
 }