From: Florian Forster <octo@collectd.org>
Date: Wed, 17 Jun 2015 14:19:25 +0000 (+0200)
Subject: src/daemon/common.c: Implement strjoin() with memcpy().
X-Git-Tag: collectd-5.5.1~105^2~1
X-Git-Url: https://git.verplant.org/?a=commitdiff_plain;h=dff336960f8b0466ebcdd21abbeddb451d29e1f9;p=collectd.git

src/daemon/common.c: Implement strjoin() with memcpy().

The previous implementation used strncat() which has the unfortunate and
unintuitive behavior of copying n+1 bytes to the buffer.
---

diff --git a/src/common.c b/src/common.c
index efd63c08..f41e9506 100644
--- a/src/common.c
+++ b/src/common.c
@@ -307,44 +307,51 @@ int strsplit (char *string, char **fields, size_t size)
 	return ((int) i);
 }
 
-int strjoin (char *dst, size_t dst_len,
+int strjoin (char *buffer, size_t buffer_size,
 		char **fields, size_t fields_num,
 		const char *sep)
 {
-	size_t field_len;
+	size_t avail;
+	char *ptr;
 	size_t sep_len;
-	int i;
-
-	memset (dst, '\0', dst_len);
+	size_t i;
 
-	if (fields_num <= 0)
+	if ((buffer_size < 1) || (fields_num <= 0))
 		return (-1);
 
+	memset (buffer, 0, buffer_size);
+	ptr = buffer;
+	avail = buffer_size - 1;
+
 	sep_len = 0;
 	if (sep != NULL)
 		sep_len = strlen (sep);
 
-	for (i = 0; i < (int)fields_num; i++)
+	for (i = 0; i < fields_num; i++)
 	{
+		size_t field_len;
+
 		if ((i > 0) && (sep_len > 0))
 		{
-			if (dst_len <= sep_len)
+			if (avail < sep_len)
 				return (-1);
 
-			strncat (dst, sep, dst_len);
-			dst_len -= sep_len;
+			memcpy (ptr, sep, sep_len);
+			ptr += sep_len;
+			avail -= sep_len;
 		}
 
 		field_len = strlen (fields[i]);
-
-		if (dst_len <= field_len)
+		if (avail < field_len)
 			return (-1);
 
-		strncat (dst, fields[i], dst_len);
-		dst_len -= field_len;
+		memcpy (ptr, fields[i], field_len);
+		ptr += field_len;
+		avail -= field_len;
 	}
 
-	return (strlen (dst));
+	assert (buffer[buffer_size - 1] == 0);
+	return (strlen (buffer));
 }
 
 int strsubstitute (char *str, char c_from, char c_to)