1 files changed, 67 insertions, 0 deletions
diff --git a/src/libnetdata/maps/system-users.h b/src/libnetdata/maps/system-users.h
new file mode 100644
index 000000000..5f7dfae1a
--- /dev/null
+++ b/src/libnetdata/maps/system-users.h
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_SYSTEM_USERS_H
+#define NETDATA_SYSTEM_USERS_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 _USERNAMES_CACHE
+#include "libnetdata/simple_hashtable.h"
+
+typedef struct usernames_cache {
+    SPINLOCK spinlock;
+    SIMPLE_HASHTABLE_USERNAMES_CACHE ht;
+} USERNAMES_CACHE;
+
+static inline STRING *system_usernames_cache_lookup_uid(USERNAMES_CACHE *uc, uid_t uid) {
+    spinlock_lock(&uc->spinlock);
+
+    SIMPLE_HASHTABLE_SLOT_USERNAMES_CACHE *sl = simple_hashtable_get_slot_USERNAMES_CACHE(&uc->ht, uid, &uid, true);
+    STRING *u = SIMPLE_HASHTABLE_SLOT_DATA(sl);
+    if(!u) {
+        char tmp[1024 + 1];
+        struct passwd pw, *result = NULL;
+
+        if (getpwuid_r(uid, &pw, tmp, sizeof(tmp), &result) != 0 || !result || !pw.pw_name || !(*pw.pw_name)) {
+            char name[50];
+            snprintfz(name, sizeof(name), "%u", uid);
+            u = string_strdupz(name);
+        }
+        else
+            u = string_strdupz(pw.pw_name);
+
+        simple_hashtable_set_slot_USERNAMES_CACHE(&uc->ht, sl, uid, u);
+    }
+
+    u = string_dup(u);
+    spinlock_unlock(&uc->spinlock);
+    return u;
+}
+
+static inline USERNAMES_CACHE *system_usernames_cache_init(void) {
+    USERNAMES_CACHE *uc = callocz(1, sizeof(*uc));
+    spinlock_init(&uc->spinlock);
+    simple_hashtable_init_USERNAMES_CACHE(&uc->ht, 100);
+    return uc;
+}
+
+static inline void system_usernames_cache_destroy(USERNAMES_CACHE *uc) {
+    spinlock_lock(&uc->spinlock);
+
+    for(SIMPLE_HASHTABLE_SLOT_USERNAMES_CACHE *sl = simple_hashtable_first_read_only_USERNAMES_CACHE(&uc->ht);
+         sl;
+         sl = simple_hashtable_next_read_only_USERNAMES_CACHE(&uc->ht, sl)) {
+        STRING *u = SIMPLE_HASHTABLE_SLOT_DATA(sl);
+        string_freez(u);
+    }
+
+    simple_hashtable_destroy_USERNAMES_CACHE(&uc->ht);
+    freez(uc);
+}
+
+#endif //NETDATA_SYSTEM_USERS_H