1 files changed, 17 insertions, 30 deletions

diff --git a/libnetdata/buffer/buffer.c b/libnetdata/buffer/buffer.c
index 488e7dd24f..64f9cce47c 100644
--- a/libnetdata/buffer/buffer.c
+++ b/libnetdata/buffer/buffer.c
@@ -81,6 +81,7 @@ void buffer_snprintf(BUFFER *wb, size_t len, const char *fmt, ...)
 
     va_list args;
     va_start(args, fmt);
+    // vsnprintfz() returns the number of bytes actually written - after possible truncation
     wb->len += vsnprintfz(&wb->buffer[wb->len], len, fmt, args);
     va_end(args);
 
@@ -89,53 +90,39 @@ void buffer_snprintf(BUFFER *wb, size_t len, const char *fmt, ...)
     // the buffer is \0 terminated by vsnprintfz
 }
 
-void buffer_vsprintf(BUFFER *wb, const char *fmt, va_list args)
-{
+inline void buffer_vsprintf(BUFFER *wb, const char *fmt, va_list args) {
     if(unlikely(!fmt || !*fmt)) return;
 
-    size_t wrote = 0, need = 2, space_remaining = 0;
+    size_t full_size_bytes = 0, need = 2, space_remaining = 0;
 
     do {
-        need += space_remaining * 2;
+        need += full_size_bytes + 2;
 
-        netdata_log_debug(D_WEB_BUFFER, "web_buffer_sprintf(): increasing web_buffer at position %zu, size = %zu, by %zu bytes (wrote = %zu)\n", wb->len, wb->size, need, wrote);
         buffer_need_bytes(wb, need);
 
         space_remaining = wb->size - wb->len - 1;
 
-        wrote = (size_t) vsnprintfz(&wb->buffer[wb->len], space_remaining, fmt, args);
+        // Use the copy of va_list for vsnprintf
+        va_list args_copy;
+        va_copy(args_copy, args);
+        // vsnprintf() returns the number of bytes required, even if bigger than the buffer provided
+        full_size_bytes = (size_t) vsnprintf(&wb->buffer[wb->len], space_remaining, fmt, args_copy);
+        va_end(args_copy);
 
-    } while(wrote >= space_remaining);
+    } while(full_size_bytes >= space_remaining);
 
-    wb->len += wrote;
+    wb->len += full_size_bytes;
 
-    // the buffer is \0 terminated by vsnprintf
+    wb->buffer[wb->len] = '\0';
+    buffer_overflow_check(wb);
 }
 
 void buffer_sprintf(BUFFER *wb, const char *fmt, ...)
 {
-    if(unlikely(!fmt || !*fmt)) return;
-
     va_list args;
-    size_t wrote = 0, need = 2, space_remaining = 0;
-
-    do {
-        need += space_remaining * 2;
-
-        netdata_log_debug(D_WEB_BUFFER, "web_buffer_sprintf(): increasing web_buffer at position %zu, size = %zu, by %zu bytes (wrote = %zu)\n", wb->len, wb->size, need, wrote);
-        buffer_need_bytes(wb, need);
-
-        space_remaining = wb->size - wb->len - 1;
-
-        va_start(args, fmt);
-        wrote = (size_t) vsnprintfz(&wb->buffer[wb->len], space_remaining, fmt, args);
-        va_end(args);
-
-    } while(wrote >= space_remaining);
-
-    wb->len += wrote;
-
-    // the buffer is \0 terminated by vsnprintf
+    va_start(args, fmt);
+    buffer_vsprintf(wb, fmt, args);
+    va_end(args);
 }
 
 // generate a javascript date, the fastest possible way...