[DTrace-devel] [PATCH] Implement dt_bpf_map_lookup_fd()

[Kris Van Hees]

Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 libdtrace/dt_bpf.c | 20 +++++++++++++++++---
 libdtrace/dt_bpf.h |  1 +
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
index 81b6e6cb..504ddcb4 100644
--- a/libdtrace/dt_bpf.c
+++ b/libdtrace/dt_bpf.c
@@ -244,18 +244,32 @@ dt_bpf_map_update(int fd, const void *key, const void *val)
 }
 
 /*
- * Retrieve the value in a map-of-maps, i.e. map[okey][ikey].
+ * Retrieve the fd for a map-in-map, i.e. map[okey] which is the fd of a map.
+ *
+ * Note: the caller is responsible for closing the fd.
  */
 int
-dt_bpf_map_lookup_inner(int fd, const void *okey, const void *ikey, void *val)
+dt_bpf_map_lookup_fd(int fd, const void *okey)
 {
 	uint32_t	id;
-	int		rc;
 
 	if (dt_bpf_map_lookup(fd, okey, &id) < 0)
 		return -1;
 
 	fd = dt_bpf_map_get_fd_by_id(id);
+
+	return fd;
+}
+
+/*
+ * Retrieve the value in a map-of-maps, i.e. map[okey][ikey].
+ */
+int
+dt_bpf_map_lookup_inner(int fd, const void *okey, const void *ikey, void *val)
+{
+	int		rc;
+
+	fd = dt_bpf_map_lookup_fd(fd, okey);
 	if (fd < 0)
 		return -1;
 
diff --git a/libdtrace/dt_bpf.h b/libdtrace/dt_bpf.h
index 17761116..ab3862aa 100644
--- a/libdtrace/dt_bpf.h
+++ b/libdtrace/dt_bpf.h
@@ -51,6 +51,7 @@ extern int dt_bpf_map_next_key(int fd, const void *key, void *nxt);
 extern int dt_bpf_map_update(int fd, const void *key, const void *val);
 extern int dt_bpf_map_delete(int fd, const void *key);
 extern int dt_bpf_map_get_fd_by_id(uint32_t id);
+extern int dt_bpf_map_lookup_fd(int fd, const void *okey);
 extern int dt_bpf_map_lookup_inner(int fd, const void *okey, const void *ikey,
 				   void *val);
 extern int dt_bpf_map_update_inner(int fd, const void *okey, const void *ikey,
-- 
2.34.1