Mallctl: Add arenas.lookup

Implement a new mallctl operation that allows looking up the arena a
region of memory belongs to.

1 files changed, 33 insertions, 1 deletions

diff --git a/src/ctl.c b/src/ctl.c
index 86c2837a..1e713a3d 100644
--- a/src/ctl.c
+++ b/src/ctl.c
@@ -139,6 +139,7 @@ CTL_PROTO(arenas_nbins)
 CTL_PROTO(arenas_nhbins)
 CTL_PROTO(arenas_nlextents)
 CTL_PROTO(arenas_create)
+CTL_PROTO(arenas_lookup)
 CTL_PROTO(prof_thread_active_init)
 CTL_PROTO(prof_active)
 CTL_PROTO(prof_dump)
@@ -373,7 +374,8 @@ static const ctl_named_node_t arenas_node[] = {
 	{NAME("bin"),		CHILD(indexed, arenas_bin)},
 	{NAME("nlextents"),	CTL(arenas_nlextents)},
 	{NAME("lextent"),	CHILD(indexed, arenas_lextent)},
-	{NAME("create"),	CTL(arenas_create)}
+	{NAME("create"),	CTL(arenas_create)},
+	{NAME("lookup"),	CTL(arenas_lookup)}
 };
 
 static const ctl_named_node_t	prof_node[] = {
@@ -2471,6 +2473,36 @@ label_return:
 	return ret;
 }
 
+static int
+arenas_lookup_ctl(tsd_t *tsd, const size_t *mib, size_t miblen, void *oldp,
+    size_t *oldlenp, void *newp, size_t newlen) {
+	int ret;
+	unsigned arena_ind;
+	void *ptr;
+	extent_t *extent;
+	arena_t *arena;
+
+	ptr = NULL;
+	ret = EINVAL;
+	malloc_mutex_lock(tsd_tsdn(tsd), &ctl_mtx);
+	WRITE(ptr, void *);
+	extent = iealloc(tsd_tsdn(tsd), ptr);
+	if (extent == NULL)
+		goto label_return;
+
+	arena = extent_arena_get(extent);
+	if (arena == NULL)
+		goto label_return;
+
+	arena_ind = arena_ind_get(arena);
+	READ(arena_ind, unsigned);
+
+	ret = 0;
+label_return:
+	malloc_mutex_unlock(tsd_tsdn(tsd), &ctl_mtx);
+	return ret;
+}
+
 /******************************************************************************/
 
 static int