CUPS plugin (#5188)

* Implement a CUPS collector plugin

* Compile cups.plugin only if enabled

* Fix build with CFLAGS

-O1 -ggdb -Wall -Wextra -Wformat-signedness -fstack-protector-all
-DNETDATA_INTERNAL_CHECKS=1 -D_FORTIFY_SOURCE=2 -DNETDATA_VERIFY_LOCKS=1

* cups.plugin check for all used functions

* Use cups-config to configure cups compiler flags

* Do not quit if cups-config is not installed

* Fix compiler warning

collectors/cups.plugin/cups_plugin.c:359:27:
warning: format '%d' expects argument of type 'int',
but argument 6 has type 'unsigned int' [-Wformat=]

* Add cups.plugin to toc and overview documentation

* cups.plugin fix plugin doc layout

* cups.plugin: Add prerequisites doc

* cups.plugin: Fix error if cups is not installed

2 files changed, 36 insertions, 0 deletions

diff --git a/libnetdata/dictionary/dictionary.c b/libnetdata/dictionary/dictionary.c
index dd94a801dc..cfcf1fbab1 100644
--- a/libnetdata/dictionary/dictionary.c
+++ b/libnetdata/dictionary/dictionary.c
@@ -292,3 +292,38 @@ int dictionary_get_all(DICTIONARY *dict, int (*callback)(void *entry, void *data
 
     return ret;
 }
+
+static int dictionary_walker_name_value(avl *a, int (*callback)(char *name, void *entry, void *data), void *data) {
+    int total = 0, ret = 0;
+
+    if(a->avl_link[0]) {
+        ret = dictionary_walker_name_value(a->avl_link[0], callback, data);
+        if(ret < 0) return ret;
+        total += ret;
+    }
+
+    ret = callback(((NAME_VALUE *)a)->name, ((NAME_VALUE *)a)->value, data);
+    if(ret < 0) return ret;
+    total += ret;
+
+    if(a->avl_link[1]) {
+        ret = dictionary_walker_name_value(a->avl_link[1], callback, data);
+        if (ret < 0) return ret;
+        total += ret;
+    }
+
+    return total;
+}
+
+int dictionary_get_all_name_value(DICTIONARY *dict, int (*callback)(char *name, void *entry, void *data), void *data) {
+    int ret = 0;
+
+    dictionary_read_lock(dict);
+
+    if(likely(dict->values_index.root))
+        ret = dictionary_walker_name_value(dict->values_index.root, callback, data);
+
+    dictionary_unlock(dict);
+
+    return ret;
+}
diff --git a/libnetdata/dictionary/dictionary.h b/libnetdata/dictionary/dictionary.h
index 61b9bfc615..9be261eb22 100644
--- a/libnetdata/dictionary/dictionary.h
+++ b/libnetdata/dictionary/dictionary.h
@@ -44,5 +44,6 @@ extern void *dictionary_get(DICTIONARY *dict, const char *name);
 extern int dictionary_del(DICTIONARY *dict, const char *name);
 
 extern int dictionary_get_all(DICTIONARY *dict, int (*callback)(void *entry, void *d), void *data);
+extern int dictionary_get_all_name_value(DICTIONARY *dict, int (*callback)(char *name, void *entry, void *d), void *data);
 
 #endif /* NETDATA_DICTIONARY_H */