common: implement bt_common_g_string_append_printf

[babeltrace.git] / src / common / common.c

diff --git a/src/common/common.c b/src/common/common.c
index d092768a147cf9a18bcabd001229d5966ff5fdfa..dacb5054fa04280e04a0f44b0bc7af2a1bb7eb20 100644 (file)
--- a/src/common/common.c
+++ b/src/common/common.c
@@ -1822,3 +1822,35 @@ end:
        return ret;
 }
 #endif /* __MINGW32__ */
+
+BT_HIDDEN
+int bt_common_g_string_append_printf(GString *str, const char *fmt, ...)
+{
+       va_list ap;
+       gsize len, allocated_len, available_len;
+       int print_len;
+
+       /* str->len excludes \0. */
+       len = str->len;
+       /* Explicitly exclude \0. */
+       allocated_len = str->allocated_len - 1;
+       available_len = allocated_len - len;
+
+       str->len = allocated_len;
+       va_start(ap, fmt);
+       print_len = vsnprintf(str->str + len, available_len + 1, fmt, ap);
+       va_end(ap);
+       if (print_len < 0) {
+               return print_len;
+       }
+       if (G_UNLIKELY(available_len < print_len)) {
+               /* Resize. */
+               g_string_set_size(str, len + print_len);
+               va_start(ap, fmt);
+               print_len = vsprintf(str->str + len, fmt, ap);
+               va_end(ap);
+       } else {
+               str->len = len + print_len;
+       }
+       return print_len;
+}