libdpkg: Namespace buffer init and done functions with buffer_filter_

This makes it clear these functions are not to initialize normal
buffer operations, but just for when a filter is in place.

lib/dpkg/buffer.c

@@ -54,7 +54,7 @@ buffer_md5_init(struct buffer_data *data)
 }
 
 static off_t
-buffer_init(struct buffer_data *data)
+buffer_filter_init(struct buffer_data *data)
 {
 	switch (data->type) {
 	case BUFFER_WRITE_MD5:
@@ -84,7 +84,7 @@ buffer_md5_done(struct buffer_data *data)
 }
 
 static off_t
-buffer_done(struct buffer_data *data)
+buffer_filter_done(struct buffer_data *data)
 {
 	switch (data->type) {
 	case BUFFER_WRITE_MD5:
@@ -142,9 +142,9 @@ buffer_hash(const void *input, void *output, int type, off_t limit)
 	struct buffer_data data = { .arg.ptr = output, .type = type };
 	off_t ret;
 
-	buffer_init(&data);
+	buffer_filter_init(&data);
 	ret = buffer_write(&data, input, limit);
-	buffer_done(&data);
+	buffer_filter_done(&data);
 
 	return ret;
 }
@@ -165,7 +165,7 @@ buffer_copy(struct buffer_data *read_data, struct buffer_data *write_data,
 
 	buf = m_malloc(bufsize);
 
-	buffer_init(write_data);
+	buffer_filter_init(write_data);
 
 	while (bufsize > 0) {
 		bytesread = buffer_read(read_data, buf, bufsize);
@@ -198,7 +198,7 @@ buffer_copy(struct buffer_data *read_data, struct buffer_data *write_data,
 	if (limit > 0)
 		ohshit(_("short read on buffer copy for %s"), desc);
 
-	buffer_done(write_data);
+	buffer_filter_done(write_data);
 
 	free(buf);