demo: sds off by one bug in specific conditions

Signed-off-by: Wesley Pettit <[email protected]>

plugins/out_stdout/stdout.c

@@ -174,6 +174,31 @@ static void cb_stdout_flush(struct flb_event_chunk *event_chunk,
     ctx = (struct flb_stdout *) out_context;
     cnt = 0;
 
+    flb_sds_t tmp;
+    flb_sds_t test = flb_sds_create_size(64);
+    if (!test) {
+        flb_errno();
+        FLB_OUTPUT_RETURN(FLB_ERROR);
+    }
+
+    flb_info("Example below will work as expected, note that all letters up to z are printed:");
+
+    tmp = flb_sds_printf(&test, "A0123456789 %s", "this-is-54-chars-1234567890-abcdefghijklmnopqrstuvwxyz");
+    flb_info("TEST: %s", tmp);
+
+    flb_sds_t test2 = flb_sds_create_size(64);
+    if (!test2) {
+        flb_errno();
+        FLB_OUTPUT_RETURN(FLB_ERROR);
+    }
+
+    flb_info("Example below shows bug, note that all letters up to z are not printed: ");
+    tmp = flb_sds_printf(&test2, "123456789 %s", "this-is-54-chars-1234567890-abcdefghijklmnopqrstuvwxyz");
+    flb_info("TEST: %s", tmp);
+
+
+
+
 #ifdef FLB_HAVE_METRICS
     /* Check if the event type is metrics, handle the payload differently */
     if (event_chunk->type == FLB_EVENT_TYPE_METRICS) {

src/flb_sds.c

@@ -416,6 +416,8 @@ flb_sds_t flb_sds_printf(flb_sds_t *sds, const char *fmt, ...)
 
     if (len < 64) len = 64;
 
+    flb_info("[sds] len=%d", len);
+
     s = *sds;
     if (flb_sds_avail(s)< len) {
         tmp = flb_sds_increase(s, len);
@@ -427,6 +429,7 @@ flb_sds_t flb_sds_printf(flb_sds_t *sds, const char *fmt, ...)
 
     va_start(ap, fmt);
     size = vsnprintf((char *) (s + flb_sds_len(s)), flb_sds_avail(s), fmt, ap);
+    flb_info("[sds] size1=%d", size);
     if (size < 0) {
         flb_warn("[%s] buggy vsnprintf return %d", __FUNCTION__, size);
         va_end(ap);
@@ -450,11 +453,14 @@ flb_sds_t flb_sds_printf(flb_sds_t *sds, const char *fmt, ...)
         }
         va_end(ap);
     }
+    flb_info("[sds] size2=%d", size);
 
     head = FLB_SDS_HEADER(s);
     head->len += size;
     s[head->len] = '\0';
 
+    flb_info("[sds] head->len=%d", head->len);
+
     return s;
 }