1 files changed, 67 insertions, 0 deletions
diff --git a/src/libnetdata/maps/system-groups.h b/src/libnetdata/maps/system-groups.h
new file mode 100644
index 00000000..fd042cd4
--- /dev/null
+++ b/src/libnetdata/maps/system-groups.h
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_SYSTEM_GROUPS_H
+#define NETDATA_SYSTEM_GROUPS_H
+
+#include "libnetdata/libnetdata.h"
+
+// --------------------------------------------------------------------------------------------------------------------
+// hashtable for caching uid to username mappings
+// key is the uid, value is username (STRING)
+
+#define SIMPLE_HASHTABLE_VALUE_TYPE STRING
+#define SIMPLE_HASHTABLE_NAME _GROUPNAMES_CACHE
+#include "libnetdata/simple_hashtable.h"
+
+typedef struct groupnames_cache {
+    SPINLOCK spinlock;
+    SIMPLE_HASHTABLE_GROUPNAMES_CACHE ht;
+} GROUPNAMES_CACHE;
+
+static inline STRING *system_groupnames_cache_lookup_gid(GROUPNAMES_CACHE *gc, gid_t gid) {
+    spinlock_lock(&gc->spinlock);
+
+    SIMPLE_HASHTABLE_SLOT_GROUPNAMES_CACHE *sl = simple_hashtable_get_slot_GROUPNAMES_CACHE(&gc->ht, gid, &gid, true);
+    STRING *g = SIMPLE_HASHTABLE_SLOT_DATA(sl);
+    if(!g) {
+        char tmp[1024 + 1];
+        struct group grp, *result = NULL;
+
+        if (getgrgid_r(gid, &grp, tmp, sizeof(tmp), &result) != 0 || !result || !grp.gr_name || !(*grp.gr_name)) {
+            char name[50];
+            snprintfz(name, sizeof(name), "%u", gid);
+            g = string_strdupz(name);
+        }
+        else
+            g = string_strdupz(grp.gr_name);
+
+        simple_hashtable_set_slot_GROUPNAMES_CACHE(&gc->ht, sl, gid, g);
+    }
+
+    g = string_dup(g);
+    spinlock_unlock(&gc->spinlock);
+    return g;
+}
+
+static inline GROUPNAMES_CACHE *system_groupnames_cache_init(void) {
+    GROUPNAMES_CACHE *gc = callocz(1, sizeof(*gc));
+    spinlock_init(&gc->spinlock);
+    simple_hashtable_init_GROUPNAMES_CACHE(&gc->ht, 100);
+    return gc;
+}
+
+static inline void system_groupnames_cache_destroy(GROUPNAMES_CACHE *gc) {
+    spinlock_lock(&gc->spinlock);
+
+    for(SIMPLE_HASHTABLE_SLOT_GROUPNAMES_CACHE *sl = simple_hashtable_first_read_only_GROUPNAMES_CACHE(&gc->ht);
+         sl;
+         sl = simple_hashtable_next_read_only_GROUPNAMES_CACHE(&gc->ht, sl)) {
+        STRING *u = SIMPLE_HASHTABLE_SLOT_DATA(sl);
+        string_freez(u);
+    }
+
+    simple_hashtable_destroy_GROUPNAMES_CACHE(&gc->ht);
+    freez(gc);
+}
+
+#endif //NETDATA_SYSTEM_GROUPS_H