soccr: Introduce flags for memory passing

There will be calls that return objects from inside library
and vice versa -- accept objects from caller. Let's have a
flag controlling who's going to free the mem in question.
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Acked-by: Andrei Vagin <avagin@virtuozzo.com>

criu/sk-tcp.c

@@ -198,7 +198,7 @@ static int dump_tcp_conn_state(struct inet_sk_desc *sk)
 	if (ret < 0)
 		goto err_iw;
 
-	buf = libsoccr_get_queue_bytes(socr, TCP_RECV_QUEUE, 1);
+	buf = libsoccr_get_queue_bytes(socr, TCP_RECV_QUEUE, SOCCR_MEM_EXCL);
 	if (buf) {
 		ret = write_img_buf(img, buf, tse.inq_len);
 		if (ret < 0)
@@ -207,7 +207,7 @@ static int dump_tcp_conn_state(struct inet_sk_desc *sk)
 		xfree(buf);
 	}
 
-	buf = libsoccr_get_queue_bytes(socr, TCP_SEND_QUEUE, 1);
+	buf = libsoccr_get_queue_bytes(socr, TCP_SEND_QUEUE, SOCCR_MEM_EXCL);
 	if (buf) {
 		ret = write_img_buf(img, buf, tse.outq_len);
 		if (ret < 0)

soccr/soccr.c

@@ -354,10 +354,14 @@ int libsoccr_save(struct libsoccr_sk *sk, struct libsoccr_sk_data *data, unsigne
 	return sizeof(struct libsoccr_sk_data);
 }
 
-char *libsoccr_get_queue_bytes(struct libsoccr_sk *sk, int queue_id, int steal)
+#define GET_Q_FLAGS	(SOCCR_MEM_EXCL)
+char *libsoccr_get_queue_bytes(struct libsoccr_sk *sk, int queue_id, unsigned flags)
 {
 	char **p, *ret;
 
+	if (flags & ~GET_Q_FLAGS)
+		return NULL;
+
 	switch (queue_id) {
 		case TCP_RECV_QUEUE:
 			p = &sk->recv_queue;
@@ -370,7 +374,7 @@ char *libsoccr_get_queue_bytes(struct libsoccr_sk *sk, int queue_id, int steal)
 	}
 
 	ret = *p;
-	if (steal)
+	if (flags & SOCCR_MEM_EXCL)
 		*p = NULL;
 
 	return ret;

soccr/soccr.h

@@ -130,6 +130,18 @@ struct libsoccr_sk_data {
 struct libsoccr_sk *libsoccr_pause(int fd);
 void libsoccr_resume(struct libsoccr_sk *sk);
 
+/*
+ * Flags for calls below
+ */
+
+/*
+ * Memory given to or taken from library is in exclusive ownership
+ * of the resulting owner. I.e. -- when taken by caller from library,
+ * the former will free() one, when given to the library, the latter
+ * is to free() it.
+ */
+#define SOCCR_MEM_EXCL		0x1
+
 /*
  * CHECKPOINTING calls
  *
@@ -172,7 +184,7 @@ int libsoccr_save(struct libsoccr_sk *sk, struct libsoccr_sk_data *data, unsigne
  * library and should free() it himself. Otherwise the buffer can
  * be claimed again and will be free by library upon _resume call.
  */
-char *libsoccr_get_queue_bytes(struct libsoccr_sk *sk, int queue_id, int steal);
+char *libsoccr_get_queue_bytes(struct libsoccr_sk *sk, int queue_id, unsigned flags);
 
 /*
  * RESTORING calls