[thin_check (rust)] add btree node checks

src/pdata/btree.rs

@@ -10,9 +10,13 @@ use crate::checksum;
 
 pub trait ValueType {
     type Value;
+    // The size of the value when on disk.
+    fn disk_size() -> u32;
     fn unpack(data: &[u8]) -> IResult<&[u8], Self::Value>;
 }
 
+const NODE_HEADER_SIZE: usize = 32;
+
 pub struct NodeHeader {
     is_leaf: bool,
     block: u64,
@@ -59,42 +63,90 @@ pub enum Node<V: ValueType> {
     },
 }
 
-pub fn unpack_node_<V: ValueType>(data: &[u8]) -> IResult<&[u8], Node<V>> {
-    use nom::multi::count;
+pub fn node_err<V>(msg: String) -> Result<V> {
+    let msg = format!("btree node error: {}", msg);
+    Err(anyhow!(msg))
+}
 
-    let (i, header) = unpack_node_header(data)?;
-    let (i, keys) = count(le_u64, header.nr_entries as usize)(i)?;
-    let nr_free = header.max_entries - header.nr_entries;
-    let (i, _padding) = count(le_u64, nr_free as usize)(i)?;
-
-    if header.is_leaf {
-        let (i, values) = count(V::unpack, header.nr_entries as usize)(i)?;
-        Ok((
-            i,
-            Node::Leaf {
-                header,
-                keys,
-                values,
-            },
-        ))
+pub fn to_any<'a, V>(r: IResult<&'a [u8], V>) -> Result<(&'a [u8], V)> {
+    if let Ok((i, v)) = r {
+        Ok((i, v))
     } else {
-        let (i, values) = count(le_u64, header.nr_entries as usize)(i)?;
-        Ok((
-            i,
-            Node::Internal {
-                header,
-                keys,
-                values,
-            },
-        ))
+        Err(anyhow!("btree node error: parse error"))
     }
 }
 
-pub fn unpack_node<V: ValueType>(data: &[u8]) -> Result<Node<V>> {
-    if let Ok((_i, node)) = unpack_node_(data) {
-        Ok(node)
+pub fn unpack_node<V: ValueType>(
+    data: &[u8],
+    ignore_non_fatal: bool,
+    is_root: bool,
+) -> Result<Node<V>> {
+    use nom::multi::count;
+
+    let (i, header) = to_any(unpack_node_header(data))?;
+
+    // FIXME: lift checks to own fn
+    if header.value_size != V::disk_size() {
+        return node_err(format!(
+            "value_size mismatch: expected {}, was {}",
+            V::disk_size(),
+            header.value_size
+        ));
+    }
+
+    let elt_size = V::disk_size() + 8;
+    if elt_size as usize * header.max_entries as usize + NODE_HEADER_SIZE > BLOCK_SIZE {
+        return node_err(format!("max_entries is too large ({})", header.max_entries));
+    }
+
+    if header.nr_entries > header.max_entries {
+        return node_err(format!("nr_entries > max_entries"));
+    }
+
+    if !ignore_non_fatal {
+        if header.max_entries % 3 != 0 {
+            return node_err(format!("max_entries is not divisible by 3"));
+        }
+
+        if !is_root {
+            let min = header.max_entries / 3;
+            if header.nr_entries < min {
+                return node_err(format!("too few entries"));
+            }
+        }
+    }
+
+    let (i, keys) = to_any(count(le_u64, header.nr_entries as usize)(i))?;
+
+    let mut last = None;
+    for k in &keys {
+        if let Some(l) = last {
+            if k <= l {
+                return node_err(format!("keys out of order"));
+            }
+        }
+
+        last = Some(k);
+    }
+
+    let nr_free = header.max_entries - header.nr_entries;
+    let (i, _padding) = to_any(count(le_u64, nr_free as usize)(i))?;
+
+    if header.is_leaf {
+        let (_i, values) = to_any(count(V::unpack, header.nr_entries as usize)(i))?;
+
+        Ok(Node::Leaf {
+            header,
+            keys,
+            values,
+        })
     } else {
-        Err(anyhow!("couldn't unpack btree node"))
+        let (_i, values) = to_any(count(le_u64, header.nr_entries as usize)(i))?;
+        Ok(Node::Internal {
+            header,
+            keys,
+            values,
+        })
     }
 }
 
@@ -104,6 +156,11 @@ pub struct ValueU64;
 
 impl ValueType for ValueU64 {
     type Value = u64;
+
+    fn disk_size() -> u32 {
+        8
+    }
+
     fn unpack(i: &[u8]) -> IResult<&[u8], u64> {
         le_u64(i)
     }
@@ -119,19 +176,21 @@ pub trait NodeVisitor<V: ValueType> {
 pub struct BTreeWalker {
     pub engine: Arc<AsyncIoEngine>,
     pub seen: Arc<Mutex<FixedBitSet>>,
+    ignore_non_fatal: bool,
 }
 
 impl BTreeWalker {
-    pub fn new(engine: AsyncIoEngine) -> BTreeWalker {
+    pub fn new(engine: AsyncIoEngine, ignore_non_fatal: bool) -> BTreeWalker {
         let nr_blocks = engine.get_nr_blocks() as usize;
         let r: BTreeWalker = BTreeWalker {
             engine: Arc::new(engine),
             seen: Arc::new(Mutex::new(FixedBitSet::with_capacity(nr_blocks))),
+            ignore_non_fatal,
         };
         r
     }
 
-    pub fn walk_nodes<NV, V>(&mut self, visitor: &mut NV, bs: &Vec<u64>) -> Result<()>
+    fn walk_nodes<NV, V>(&mut self, visitor: &mut NV, bs: &Vec<u64>) -> Result<()>
     where
         NV: NodeVisitor<V>,
         V: ValueType,
@@ -148,13 +207,13 @@ impl BTreeWalker {
         self.engine.read_many(&mut blocks)?;
 
         for b in blocks {
-            self.walk_node(visitor, &b)?;
+            self.walk_node(visitor, &b, false)?;
         }
 
         Ok(())
     }
 
-    pub fn walk_node<NV, V>(&mut self, visitor: &mut NV, b: &Block) -> Result<()>
+    fn walk_node<NV, V>(&mut self, visitor: &mut NV, b: &Block, is_root: bool) -> Result<()>
     where
         NV: NodeVisitor<V>,
         V: ValueType,
@@ -168,7 +227,7 @@ impl BTreeWalker {
             return Err(anyhow!("checksum failed for node {}, {:?}", b.loc, bt));
         }
 
-        let node = unpack_node::<V>(&b.get_data())?;
+        let node = unpack_node::<V>(&b.get_data(), self.ignore_non_fatal, is_root)?;
         visitor.visit(self, &b, &node)?;
 
         if let Node::Internal {
@@ -182,6 +241,18 @@ impl BTreeWalker {
 
         Ok(())
     }
+
+    pub fn walk<NV, V>(
+        &mut self,
+        visitor: &mut NV,
+        root: &Block,
+    ) -> Result<()>
+    where
+        NV: NodeVisitor<V>,
+        V: ValueType,
+    {
+       self.walk_node(visitor, &root, true)
+    }
 }
 
 //------------------------------------------