Fix and clarify gnuf_printf

include/ucore/ucore_buffer.h

@@ -59,13 +59,16 @@ void uc_gbuf_unref(GBuf *buf);
 int uc_gbuf_append(GBuf *buf,const void *data,size_t len);
 
 /** Do printf formatting on a GBuf.
- * The buffer will grow as needed.
+ * The buffer will grow as needed,
+ * The buffer ensures that the added string will be nul terminated,
+ * however the nul terminator is not counted in the ->used member.
  *
  * @param buf The GBuf
  * @param fmt printf stype formatting string
  * @param ... format arguments
  * 
- * @return The number of chars written, or negative if an error occurs
+ * @return The number of chars written excluding the terminating nul
+ * character , or negative if an error occurs
  */
 int uc_gbuf_printf(GBuf *buf, const char *fmt, ...);
 

src/ucore_buffer.c

@@ -90,8 +90,9 @@ int uc_gbuf_printf(GBuf *buf, const char *fmt, ...)
 
     } while(rc >= remaining);
 
-    if(rc > 0)
+    if(rc > 0) {
         buf->used += rc; 
+    }
    
    va_end(ap);
 

test/test_buffer.c

@@ -11,6 +11,22 @@ START_TEST (test_new_gbuf)
     fail_if(buf->ref_cnt != 1);
     fail_if(buf->buf == NULL);
     fail_if(buf->used != 0);
+
+END_TEST
+
+START_TEST (test_gbuf_grow)
+    GBuf *buf = uc_new_gbuf(33);
+    int rc;
+
+    fail_if(buf == NULL);
+    fail_if(buf->len != 33);
+
+    rc = uc_gbuf_grow(buf, 128);
+
+    fail_if(rc != 0);
+    fail_if(buf->len < 128 + 33);
+    fail_if(buf->used != 0);
+
 END_TEST
 
 START_TEST (test_gbuf_append1)
@@ -27,6 +43,32 @@ START_TEST (test_gbuf_append1)
 
 END_TEST
 
+START_TEST (test_gbuf_printf1)
+    int rc;
+    GBuf *buf = uc_new_gbuf(10);
+
+    fail_if(buf == NULL);
+
+    rc = uc_gbuf_printf(buf, "test %d", 1);
+    fail_if(rc != 6, "rc was %d", rc);
+    fail_if(buf->used != 6, "buf->used was %d", buf->used);
+    fail_if(strcmp("test 1", buf->buf) != 0);
+
+END_TEST
+
+START_TEST (test_gbuf_printf2)
+    int rc;
+    GBuf *buf = uc_new_gbuf(8);
+
+    fail_if(buf == NULL);
+
+    rc = uc_gbuf_printf(buf, "test %d test %d test %d", 1, 2, 3);
+    fail_if(rc != 20, "rc was %d", rc);
+    fail_if(buf->used != 20, "buf->used was %d", buf->used);
+    fail_if(strcmp("test 1 test 2 test 3", buf->buf) != 0);
+
+END_TEST
+
 
 Suite *buffer_suite(void)
 {
@@ -34,6 +76,9 @@ Suite *buffer_suite(void)
     TCase *tc = tcase_create("buffer (GBuf) tests");
     tcase_add_test(tc, test_new_gbuf);
     tcase_add_test(tc, test_gbuf_append1);
+    tcase_add_test(tc, test_gbuf_grow);
+    tcase_add_test(tc, test_gbuf_printf1);
+    tcase_add_test(tc, test_gbuf_printf2);
 
     suite_add_tcase(s, tc);