From 6a15cce5400d46dff8b1d5a8aeeff862c3bbdde5 Mon Sep 17 00:00:00 2001
From: Dietmar Maurer <dietmar@proxmox.com>
Date: Tue, 13 Apr 2021 11:44:06 +0200
Subject: [PATCH] tape: SgTapeReader::read_block - disable reading beyond EOF

---
 src/tape/drive/lto/sg_tape.rs | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/tape/drive/lto/sg_tape.rs b/src/tape/drive/lto/sg_tape.rs
index 3f73e025..7faa1639 100644
--- a/src/tape/drive/lto/sg_tape.rs
+++ b/src/tape/drive/lto/sg_tape.rs
@@ -694,19 +694,30 @@ impl Drop for SgTape {
 
 pub struct SgTapeReader<'a> {
     sg_tape: &'a mut SgTape,
+    end_of_file: bool,
 }
 
 impl <'a> SgTapeReader<'a> {
 
     pub fn new(sg_tape: &'a mut SgTape) -> Self {
-        Self { sg_tape }
+        Self { sg_tape, end_of_file: false, }
     }
 }
 
 impl <'a> BlockRead for SgTapeReader<'a> {
 
     fn read_block(&mut self, buffer: &mut [u8]) -> Result<usize, BlockReadError> {
-        self.sg_tape.read_block(buffer)
+        if self.end_of_file {
+            return Err(BlockReadError::Error(proxmox::io_format_err!("detected read after EOF!")));
+        }
+        match self.sg_tape.read_block(buffer) {
+            Ok(usize) => Ok(usize),
+            Err(BlockReadError::EndOfFile) => {
+                self.end_of_file = true;
+                Err(BlockReadError::EndOfFile)
+            },
+            Err(err) => Err(err),
+        }
     }
 }