No prefetch in "stream_open()"

"$this->request_chunk(256 * 1024);" at the end of "stream_open()"
fetches a chunk of file contents. But when "stream_close()" is called
without calling "stream_read()", it tries to read status code from
"request_chunk()". Which lead to stream_close() to return false.

After this, regular files are displayed as folders. Previews are not
generated.

Instead of fetching chunk in "stream_open()", make the "stream_read()"
call both "request_chunk()" and "read_chunk()" it it.

Issue #25788

Signed-off-by: Rae Kim <rae.kim@raekim.me>

apps/files_external/lib/Lib/Storage/SFTPReadStream.php

@@ -112,8 +112,6 @@ public function stream_open($path, $mode, $options, &$opened_path) {
 				return false;
 		}
 
-		$this->request_chunk(256 * 1024);
-
 		return true;
 	}
 
@@ -126,12 +124,10 @@ public function stream_tell() {
 	}
 
 	public function stream_read($count) {
-		if (!$this->eof && strlen($this->buffer) < $count) {
+		while (strlen($this->buffer) < $count && !$this->eof) {
+			$this->request_chunk(256 * 1024);
 			$chunk = $this->read_chunk();
 			$this->buffer .= $chunk;
-			if (!$this->eof) {
-				$this->request_chunk(256 * 1024);
-			}
 		}
 
 		$data = substr($this->buffer, 0, $count);