Fix empty images

src/mastodon.rs

@@ -4,7 +4,7 @@ use megalodon::entities::UploadMedia;
 use megalodon::generator;
 use megalodon::megalodon::PostStatusInputOptions;
 use megalodon::{self, megalodon::UploadMediaInputOptions};
-use std::io::Cursor;
+use std::io::{Cursor, Seek, SeekFrom};
 
 use crate::{StdError, APP_USER_AGENT};
 
@@ -25,7 +25,8 @@ pub async fn toot(text: &str, img: Option<Box<Cursor<Vec<u8>>>>) -> StdError<()>
         Some(APP_USER_AGENT.into()),
     );
     let mut ops = PostStatusInputOptions::default();
-    if let Some(img) = img {
+    if let Some(mut img) = img {
+        img.as_mut().seek(SeekFrom::Start(0))?;
         let media = client
             .upload_media_reader(img, Some(&UploadMediaInputOptions::default()))
             .await?;