tape: hide internal use of all zero uuid for unassigned tapes

a tape assigned to a pool but no media-set, gets the special 'all zero'
media set in it's MediaSetLabel. Instead of having that constant
scattered all over the code, hide this fact by using wrapper functions
to initialize it that way and to check for it

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/api2/tape/drive.rs

@@ -528,7 +528,7 @@ fn write_media_label(
             label.label_text,
             pool
         );
-        let set = MediaSetLabel::with_data(pool, [0u8; 16].into(), 0, label.ctime, None);
+        let set = MediaSetLabel::new_unassigned(pool, label.ctime);
 
         drive.write_media_set_label(&set, None)?;
 
@@ -575,7 +575,7 @@ fn write_media_label(
             if let Some(ref pool) = pool {
                 match info.media_set_label {
                     Some(set) => {
-                        if set.uuid != [0u8; 16].into() {
+                        if !set.unassigned() {
                             bail!("verify media set label failed - got wrong set uuid");
                         }
                         if &set.pool != pool {
@@ -1301,7 +1301,7 @@ pub fn catalog_media(
                     return Ok(());
                 }
                 Some(ref set) => {
-                    if set.uuid.as_ref() == [0u8; 16] {
+                    if set.unassigned() {
                         // media is empty
                         task_log!(worker, "media is empty");
                         let _lock = lock_unassigned_media_pool(TAPE_STATUS_DIR)?;

src/api2/tape/media.rs

@@ -336,8 +336,7 @@ pub fn destroy_media(label_text: String, force: Option<bool>) -> Result<(), Erro
 
     if !force {
         if let Some(ref set) = media_id.media_set_label {
-            let is_empty = set.uuid.as_ref() == [0u8; 16];
-            if !is_empty {
+            if !set.unassigned() {
                 bail!(
                     "media '{}' contains data (please use 'force' flag to remove.",
                     label_text

src/tape/file_formats/mod.rs

@@ -168,4 +168,12 @@ impl MediaSetLabel {
             encryption_key_fingerprint,
         }
     }
+
+    pub fn new_unassigned(pool: &str, ctime: i64) -> Self {
+        Self::with_data(pool, [0u8; 16].into(), 0, ctime, None)
+    }
+
+    pub fn unassigned(&self) -> bool {
+        self.uuid.as_ref() == [0u8; 16]
+    }
 }

src/tape/inventory.rs

@@ -185,7 +185,7 @@ impl Inventory {
             // do not overwrite unsaved pool assignments
             if media_id.media_set_label.is_none() {
                 if let Some(ref set) = previous.id.media_set_label {
-                    if set.uuid.as_ref() == [0u8; 16] {
+                    if set.unassigned() {
                         media_id.media_set_label = Some(set.clone());
                     }
                 }
@@ -251,15 +251,11 @@ impl Inventory {
     pub fn lookup_media_pool(&self, uuid: &Uuid) -> Option<(&str, bool)> {
         match self.map.get(uuid) {
             None => None,
-            Some(entry) => {
-                match entry.id.media_set_label {
-                    None => None, // not assigned to any pool
-                    Some(ref set) => {
-                        let is_empty = set.uuid.as_ref() == [0u8; 16];
-                        Some((&set.pool, is_empty))
-                    }
-                }
-            }
+            Some(entry) => entry
+                .id
+                .media_set_label
+                .as_ref()
+                .map(|set| (set.pool.as_str(), set.unassigned())),
         }
     }
 
@@ -275,7 +271,7 @@ impl Inventory {
                         continue; // belong to another pool
                     }
 
-                    if set.uuid.as_ref() == [0u8; 16] {
+                    if set.unassigned() {
                         list.push(MediaId {
                             label: entry.id.label.clone(),
                             media_set_label: None,
@@ -298,7 +294,7 @@ impl Inventory {
             match entry.id.media_set_label {
                 None => continue, // not assigned to any pool
                 Some(ref set) => {
-                    if set.uuid.as_ref() != [0u8; 16] {
+                    if set.unassigned() {
                         list.push(entry.id.clone());
                     }
                 }
@@ -410,7 +406,7 @@ impl Inventory {
             .map
             .values()
             .filter_map(|entry| entry.id.media_set_label.as_ref())
-            .filter(|set| set.pool == pool && set.uuid.as_ref() != [0u8; 16]);
+            .filter(|set| set.pool == pool && !set.unassigned());
 
         for set in set_list {
             match last_set {
@@ -435,7 +431,7 @@ impl Inventory {
             .map
             .values()
             .filter_map(|entry| entry.id.media_set_label.as_ref())
-            .filter(|set| set.pool == pool && set.uuid.as_ref() != [0u8; 16]);
+            .filter(|set| set.pool == pool && !set.unassigned());
 
         for set in set_list {
             if set.uuid != uuid && set.ctime >= ctime {
@@ -600,7 +596,7 @@ impl Inventory {
 
         let uuid = label.uuid.clone();
 
-        let set = MediaSetLabel::with_data(pool, [0u8; 16].into(), 0, ctime, None);
+        let set = MediaSetLabel::new_unassigned(pool, ctime);
 
         self.store(
             MediaId {

src/tape/media_pool.rs

@@ -181,7 +181,7 @@ impl MediaPool {
             // should never trigger
             return (MediaStatus::Unknown, location); // belong to another pool
         }
-        if set.uuid.as_ref() == [0u8; 16] {
+        if set.unassigned() {
             // not assigned to any pool
             return (MediaStatus::Writable, location);
         }