fix: 💥 handle directory entries with length of 0 according to PMTiles…

… spec

PMTiles spec states that dir entries must have a length that is greater than 0, therefore this library will handle such cases as errors while reading,  writing and constructing PMTiles archives

src/directory.rs

@@ -136,7 +136,16 @@ impl Directory {
 
         // read length
         for i in 0..num_entries {
-            entries[i].length = read_varint([_], [reader])?;
+            let len = read_varint([_], [reader])?;
+
+            if len == 0 {
+                return Err(std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    "Length of a directory entry must be greater than 0.",
+                ));
+            }
+
+            entries[i].length = len;
         }
 
         // read offset
@@ -178,6 +187,12 @@ impl Directory {
 
         // write length
         for entry in &self.entries {
+            if entry.length == 0 {
+                return Err(std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    "Length of a directory entry must be greater than 0.",
+                ));
+            }
             write_varint([writer], [entry.length])?;
         }
 
@@ -295,8 +310,9 @@ impl Directory {
     /// * `compression` - Compression to use
     ///
     /// # Errors
-    /// Will return [`Err`] if `compression` is set to [`Compression::Unknown`] or an I/O
-    /// error occurred while writing to `output`.
+    /// Will return [`Err`] if `compression` is set to [`Compression::Unknown`], the
+    /// directory includes a entry with a length of 0 or an I/O error occurred
+    /// while writing to `output`.
     ///
     /// # Example
     /// ```rust
@@ -320,8 +336,9 @@ impl Directory {
     /// * `compression` - Compression to use
     ///
     /// # Errors
-    /// Will return [`Err`] if `compression` is set to [`Compression::Unknown`] or an I/O
-    /// error occurred while writing to `output`.
+    /// Will return [`Err`] if `compression` is set to [`Compression::Unknown`], the
+    /// directory includes a entry with a length of 0 or an I/O error occurred
+    /// while writing to `output`.
     ///
     /// # Example
     /// ```rust
@@ -462,4 +479,22 @@ mod test {
 
         Ok(())
     }
+
+    #[test]
+    fn test_to_writer_invalid_entry() {
+        let mut dir = Directory {
+            entries: Vec::new(),
+        };
+
+        dir.entries.push(Entry {
+            length: 0,
+            offset: 0,
+            run_length: 0,
+            tile_id: 0,
+        });
+
+        let mut buf = Vec::<u8>::with_capacity(10);
+        let mut writer = Cursor::new(&mut buf);
+        assert!(dir.to_writer(&mut writer, ROOT_DIR_COMPRESSION).is_err());
+    }
 }

src/pmtiles.rs

@@ -136,8 +136,12 @@ impl<R> PMTiles<R> {
     /// Note that the data should already be compressed if [`Self::tile_compression`] is set to a value other than [`Compression::None`].
     /// The data will **NOT** be compressed automatically.  
     /// The [`util`-module](crate::util) includes utilities to compress data.
-    pub fn add_tile(&mut self, tile_id: u64, data: impl Into<Vec<u8>>) {
-        self.tile_manager.add_tile(tile_id, data);
+    ///
+    /// # Errors
+    /// Will return [`Err`] if `data` converts into an empty `Vec`.
+    ///
+    pub fn add_tile(&mut self, tile_id: u64, data: impl Into<Vec<u8>>) -> Result<()> {
+        self.tile_manager.add_tile(tile_id, data)
     }
 
     /// Removes a tile from this archive.

src/tile_manager.rs

@@ -56,9 +56,16 @@ impl<R> TileManager<R> {
     }
 
     /// Add tile to writer
-    pub fn add_tile(&mut self, tile_id: u64, data: impl Into<Vec<u8>>) {
+    pub fn add_tile(&mut self, tile_id: u64, data: impl Into<Vec<u8>>) -> Result<()> {
         let vec: Vec<u8> = data.into();
 
+        if vec.is_empty() {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidInput,
+                "A tile must have at least 1 byte of data.",
+            ));
+        }
+
         // remove tile just to make sure that there
         // are no unreachable tiles
         self.remove_tile(tile_id);
@@ -70,6 +77,8 @@ impl<R> TileManager<R> {
         self.data_by_hash.insert(hash, vec);
 
         self.ids_by_hash.entry(hash).or_default().insert(tile_id);
+
+        Ok(())
     }
 
     pub(crate) fn add_offset_tile(&mut self, tile_id: u64, offset: u64, length: u32) {
@@ -262,7 +271,7 @@ mod test {
 
         let contents = vec![1u8, 3, 3, 7, 4, 2];
 
-        manager.add_tile(42, contents.clone());
+        manager.add_tile(42, contents.clone())?;
 
         let opt = manager.get_tile(42)?;
 
@@ -273,48 +282,54 @@ mod test {
     }
 
     #[test]
-    fn test_add_tile() {
+    fn test_add_tile() -> Result<()> {
         let mut manager = TileManager::default();
 
-        manager.add_tile(1337, vec![1, 3, 3, 7, 4, 2]);
+        manager.add_tile(1337, vec![1, 3, 3, 7, 4, 2])?;
         assert_eq!(manager.data_by_hash.len(), 1);
 
-        manager.add_tile(42, vec![4, 2, 1, 3, 3, 7]);
+        manager.add_tile(42, vec![4, 2, 1, 3, 3, 7])?;
         assert_eq!(manager.data_by_hash.len(), 2);
+
+        Ok(())
     }
 
     #[test]
-    fn test_add_tile_dedup() {
+    fn test_add_tile_dedup() -> Result<()> {
         let mut manager = TileManager::default();
 
         let contents = vec![1u8, 3, 3, 7, 4, 2];
 
-        manager.add_tile(42, contents.clone());
-        manager.add_tile(1337, contents);
+        manager.add_tile(42, contents.clone())?;
+        manager.add_tile(1337, contents)?;
 
         assert_eq!(manager.data_by_hash.len(), 1);
+
+        Ok(())
     }
 
     #[test]
-    fn test_add_tile_update() {
+    fn test_add_tile_update() -> Result<()> {
         let mut manager = TileManager::default();
 
-        manager.add_tile(1337, vec![1, 3, 3, 7, 4, 2]);
+        manager.add_tile(1337, vec![1, 3, 3, 7, 4, 2])?;
         assert_eq!(manager.data_by_hash.len(), 1);
         assert_eq!(manager.tile_by_id.len(), 1);
         assert_eq!(manager.ids_by_hash.len(), 1);
 
-        manager.add_tile(1337, vec![4, 2, 1, 3, 3, 7]);
+        manager.add_tile(1337, vec![4, 2, 1, 3, 3, 7])?;
         assert_eq!(manager.data_by_hash.len(), 1);
         assert_eq!(manager.tile_by_id.len(), 1);
         assert_eq!(manager.ids_by_hash.len(), 1);
+
+        Ok(())
     }
 
     #[test]
-    fn test_remove_tile() {
+    fn test_remove_tile() -> Result<()> {
         let mut manager = TileManager::default();
 
-        manager.add_tile(42, vec![1u8, 3, 3, 7, 4, 2]);
+        manager.add_tile(42, vec![1u8, 3, 3, 7, 4, 2])?;
 
         assert_eq!(manager.tile_by_id.len(), 1);
         assert_eq!(manager.data_by_hash.len(), 1);
@@ -325,6 +340,8 @@ mod test {
         assert_eq!(manager.tile_by_id.len(), 0);
         assert_eq!(manager.data_by_hash.len(), 0);
         assert_eq!(manager.ids_by_hash.len(), 0);
+
+        Ok(())
     }
 
     #[test]
@@ -337,13 +354,13 @@ mod test {
     }
 
     #[test]
-    fn test_remove_tile_dupe() {
+    fn test_remove_tile_dupe() -> Result<()> {
         let mut manager = TileManager::default();
 
         let contents = vec![1u8, 3, 3, 7, 4, 2];
-        manager.add_tile(69, contents.clone());
-        manager.add_tile(42, contents.clone());
-        manager.add_tile(1337, contents);
+        manager.add_tile(69, contents.clone())?;
+        manager.add_tile(42, contents.clone())?;
+        manager.add_tile(1337, contents)?;
 
         assert_eq!(manager.data_by_hash.len(), 1);
 
@@ -358,6 +375,8 @@ mod test {
         manager.remove_tile(42);
         assert_eq!(manager.data_by_hash.len(), 0);
         assert_eq!(manager.ids_by_hash.len(), 0);
+
+        Ok(())
     }
 
     #[test]
@@ -368,9 +387,9 @@ mod test {
         let tile_42 = vec![42u8, 3, 3, 7, 4, 2];
         let tile_1337 = vec![1u8, 3, 3, 7, 4, 2];
 
-        manager.add_tile(0, tile_0.clone());
-        manager.add_tile(42, tile_42.clone());
-        manager.add_tile(1337, tile_1337.clone());
+        manager.add_tile(0, tile_0.clone())?;
+        manager.add_tile(42, tile_42.clone())?;
+        manager.add_tile(1337, tile_1337.clone())?;
 
         let result = manager.finish()?;
         let data = result.data;
@@ -391,9 +410,9 @@ mod test {
 
         let content = vec![1u8, 3, 3, 7, 4, 2];
 
-        manager.add_tile(0, content.clone());
-        manager.add_tile(1, vec![1]);
-        manager.add_tile(1337, content.clone());
+        manager.add_tile(0, content.clone())?;
+        manager.add_tile(1, vec![1])?;
+        manager.add_tile(1337, content.clone())?;
 
         let result = manager.finish()?;
         let data = result.data;
@@ -419,8 +438,8 @@ mod test {
         manager.add_offset_tile(0, 0, 4);
         manager.add_offset_tile(5, 0, 4);
         manager.add_offset_tile(10, 4, 4);
-        manager.add_tile(15, vec![1, 3, 3, 7]);
-        manager.add_tile(20, vec![1, 3, 3, 7]);
+        manager.add_tile(15, vec![1, 3, 3, 7])?;
+        manager.add_tile(20, vec![1, 3, 3, 7])?;
 
         let result = manager.finish()?;
         let data = result.data;
@@ -451,11 +470,11 @@ mod test {
 
         let content = vec![1u8, 3, 3, 7, 4, 2];
 
-        manager.add_tile(0, content.clone());
-        manager.add_tile(1, content.clone());
-        manager.add_tile(2, content.clone());
-        manager.add_tile(3, content.clone());
-        manager.add_tile(4, content);
+        manager.add_tile(0, content.clone())?;
+        manager.add_tile(1, content.clone())?;
+        manager.add_tile(2, content.clone())?;
+        manager.add_tile(3, content.clone())?;
+        manager.add_tile(4, content)?;
 
         let result = manager.finish()?;
         let directory = result.directory;
@@ -474,10 +493,10 @@ mod test {
         let mut manager = TileManager::default();
 
         // add tiles in random order
-        manager.add_tile(42, vec![42]);
-        manager.add_tile(1337, vec![13, 37]);
-        manager.add_tile(69, vec![69]);
-        manager.add_tile(1, vec![1]);
+        manager.add_tile(42, vec![42])?;
+        manager.add_tile(1337, vec![13, 37])?;
+        manager.add_tile(69, vec![69])?;
+        manager.add_tile(1, vec![1])?;
 
         let result = manager.finish()?;
         let directory = result.directory;