proxy: add log prefix and fix line break

Signed-off-by: Yiwei Zhang <zzyiwei@chromium.org>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>

src/proxy/proxy_common.c

@@ -13,8 +13,35 @@ struct proxy_renderer proxy_renderer;
 void
 proxy_log(const char *fmt, ...)
 {
+   const char prefix[] = "proxy: ";
+   char line[1024];
+   size_t len;
    va_list va;
+   int ret;
+
+   len = ARRAY_SIZE(prefix) - 1;
+   memcpy(line, prefix, len);
+
    va_start(va, fmt);
-   virgl_logv(fmt, va);
+   ret = vsnprintf(line + len, ARRAY_SIZE(line) - len, fmt, va);
    va_end(va);
+
+   if (ret < 0) {
+      const char log_error[] = "log error";
+      memcpy(line + len, log_error, ARRAY_SIZE(log_error) - 1);
+      len += ARRAY_SIZE(log_error) - 1;
+   } else if ((size_t)ret < ARRAY_SIZE(line) - len) {
+      len += ret;
+   } else {
+      len = ARRAY_SIZE(line) - 1;
+   }
+
+   /* make room for newline */
+   if (len + 1 >= ARRAY_SIZE(line))
+      len--;
+
+   line[len++] = '\n';
+   line[len] = '\0';
+
+   virgl_log(line);
 }