libcollectdclient: Document the used macros.

They're probably not obvious unless you've doe quite
some C coding.

diff --git a/src/libcollectdclient/client.c b/src/libcollectdclient/client.c
index 2ec277424c56d027a01232aeed5104c5011c1b59..baffe9954cb8220c8905da4aab32faa53bc751ee 100644 (file)
--- a/src/libcollectdclient/client.c
+++ b/src/libcollectdclient/client.c
@@ -61,6 +61,10 @@
 
 #include "client.h"
 
+/* Secure/static macros. They work like `strcpy' and `strcat', but assure null
+ * termination. They work for static buffers only, because they use `sizeof'.
+ * The `SSTRCATF' combines the functionality of `snprintf' and `strcat' which
+ * is very useful to add formatted stuff to the end of a buffer. */
 #define SSTRCPY(d,s) do { \
     strncpy ((d), (s), sizeof (d)); \
     (d)[sizeof (d) - 1] = 0; \