box: reopen completed tree spools for upload

userland/box/src/transfer.rs

@@ -1,6 +1,5 @@
 //! Bounded streaming transfers. Payloads stay in HTTP/VFS, not RPC responses.
 use super::*;
-use std::io::{Seek, SeekFrom};
 
 pub fn file_path(id: &str, path: &str) -> Result<String> {
     if !path.starts_with('/') || path == "/" {
@@ -231,9 +230,11 @@ pub fn put_tree(h: &str, p: PutTree) -> Result<OkResult> {
     let mut tar = tar::Builder::new(f);
     tar.follow_symlinks(false);
     append_tree(&mut tar, Path::new(&p.from_vfs_dir), Path::new("."))?;
-    let mut f = tar.into_inner()?;
+    let mut output = tar.into_inner()?;
+    output.flush()?;
+    drop(output);
+    let mut f = File::open(spool.path())?;
     let len = f.metadata()?.len();
-    f.seek(SeekFrom::Start(0))?;
     let remote = remote_tmp();
     let result = (|| -> Result<()> {
         put(h, &p.id, &remote, &mut f, len)?;