blobmsg: blobmsg_vprintf: prefer vsnprintf

Better safe than sorry and while at it add handling of possible
*printf() failures.

Reviewed-by: Jo-Philipp Wich <jo@mein.io>
Signed-off-by: Petr Štetiar <ynezz@true.cz>

diff --git a/blobmsg.c b/blobmsg.c
index 1dd57e156122ec06d1797f9a17fb10938c2fc356..3e34821cc9284c64c9f220ab2b2de66b4c42a4a1 100644 (file)
--- a/blobmsg.c
+++ b/blobmsg.c
@@ -290,10 +290,17 @@ int blobmsg_vprintf(struct blob_buf *buf, const char *name, const char *format,
        len = vsnprintf(&cbuf, sizeof(cbuf), format, arg2);
        va_end(arg2);
 
+       if (len < 0)
+               return -1;
+
        sbuf = blobmsg_alloc_string_buffer(buf, name, len + 1);
        if (!sbuf)
                return -1;
-       ret = vsprintf(sbuf, format, arg);
+
+       ret = vsnprintf(sbuf, len + 1, format, arg);
+       if (ret < 0)
+               return -1;
+
        blobmsg_add_string_buffer(buf);
 
        return ret;