[pbs-devel] [PATCH proxmox-backup] tools/sgutils2: add size workaround for mode_sense

[Dominik Csapak <d.csapak@proxmox.com>]

Some drives will always return the number of bytes given in the
allocation_length field, but correctly report the data len in the mode
sense header. Simply ignore the excess data.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
 src/tools/sgutils2.rs | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/tools/sgutils2.rs b/src/tools/sgutils2.rs
index 96625301..6ee19ff2 100644
--- a/src/tools/sgutils2.rs
+++ b/src/tools/sgutils2.rs
@@ -757,10 +757,14 @@ pub fn scsi_mode_sense<F: AsRawFd, P: Endian>(
         let mut reader = &data[..];
 
         let head: ModeParameterHeader = unsafe { reader.read_be_value()? };
-
-        if (head.mode_data_len as usize + 2) != data.len() {
-            let len = head.mode_data_len;
-            bail!("wrong mode_data_len: {}, expected {}", len, data.len() - 2);
+        let expected_len = head.mode_data_len as usize + 2;
+
+        if data.len() < expected_len {
+            bail!("wrong mode_data_len: got {}, expected {}", data.len(), expected_len);
+        } else if data.len() > expected_len {
+            // Note: Quantum hh7 returns the allocation_length instead of real data_len
+            let header_size = std::mem::size_of::<ModeParameterHeader>();
+            reader = &data[header_size..expected_len];
         }
 
         if disable_block_descriptor && head.block_descriptior_len != 0 {
-- 
2.20.1