Add conversion methods between chunk data

src/lib/rainbowutils.rs

@@ -1,17 +1,21 @@
-use byteorder::{BigEndian, ByteOrder, ReadBytesExt};
-use rand::AsByteSliceMut;
+use byteorder::{BigEndian, ByteOrder};
 use std::collections::HashMap;
+use std::convert::{TryFrom, TryInto};
 use std::fs::File;
 use std::io::{BufReader, Read};
 use std::io::{Error, ErrorKind};
 
 pub const BDF_HDR: &[u8; 11] = b"BDF\x01RAINBOW";
 pub const NULL_BYTES: &[u8; 4] = &[0u8; 4];
+pub const META_CHUNK_NAME: &str = "META";
+pub const HTBL_CHUNK_NAME: &str = "HTBL";
+pub const DTBL_CHUNK_NAME: &str = "DTBL";
 
 pub struct BinaryDictionaryFile {
     name: String,
     reader: BufReader<File>,
     metadata: Option<MetaChunk>,
+    lookup_table: Option<HashLookupTable>,
 }
 
 #[derive(Debug, Clone)]
@@ -30,6 +34,11 @@ pub struct MetaChunk {
     compression_method: Option<String>,
 }
 
+#[derive(Debug, Clone)]
+pub struct HashLookupTable {
+    entries: HashMap<u32, HashEntry>,
+}
+
 #[derive(Debug, Clone)]
 pub struct HashEntry {
     id: u32,
@@ -44,22 +53,48 @@ pub struct DataEntry {
 }
 
 impl BinaryDictionaryFile {
-    fn new(reader: BufReader<File>) -> Self {
+    pub fn new(reader: BufReader<File>) -> Self {
         Self {
             name: "".to_string(),
             metadata: None,
+            lookup_table: None,
             reader,
         }
     }
 
-    fn read_metadata(&mut self) -> Result<MetaChunk, Error> {
+    pub fn read_metadata(&mut self) -> Result<&MetaChunk, Error> {
         if !self.validate_header() {
-            return Err(Error::new(ErrorKind::InvalidData, "Invalid BDF Header!"));
+            return Err(Error::new(ErrorKind::InvalidData, "invalid BDF Header"));
         }
-        let meta_chunk = self.next_chunk().as_meta_chunk();
-        self.metadata = Some(meta_chunk.clone());
+        let meta_chunk: MetaChunk = self.next_chunk()?.try_into()?;
+        self.metadata = Some(meta_chunk);
 
-        Ok(meta_chunk)
+        if let Some(chunk) = &self.metadata {
+            Ok(&chunk)
+        } else {
+            Err(Error::new(
+                ErrorKind::Other,
+                "Failed to read self assigned metadata.",
+            ))
+        }
+    }
+
+    pub fn read_lookup_table(&mut self) -> Result<&HashLookupTable, Error> {
+        match &self.metadata {
+            None => self.read_metadata()?,
+            Some(t) => t,
+        };
+        let lookup_table: HashLookupTable = self.next_chunk()?.try_into()?;
+        self.lookup_table = Some(lookup_table);
+
+        if let Some(chunk) = &self.lookup_table {
+            Ok(&chunk)
+        } else {
+            Err(Error::new(
+                ErrorKind::Other,
+                "failed to read self assigned chunk",
+            ))
+        }
     }
 
     fn validate_header(&mut self) -> bool {
@@ -69,52 +104,109 @@ impl BinaryDictionaryFile {
         header == BDF_HDR.as_ref()
     }
 
-    fn next_chunk(&mut self) -> GenericChunk {
+    /// Returns the next chunk if one is available.
+    pub fn next_chunk(&mut self) -> Result<GenericChunk, Error> {
         let mut length_raw = [0u8; 4];
-        let _ = self.reader.read(&mut length_raw);
+        let _ = self.reader.read_exact(&mut length_raw)?;
         let length = BigEndian::read_u32(&mut length_raw);
         let mut name_raw = [0u8; 4];
-        let _ = self.reader.read(&mut name_raw);
-        let name =
-            String::from_utf8(name_raw.to_vec()).expect("Failed to parse chunk name to string!");
+        let _ = self.reader.read_exact(&mut name_raw)?;
+        let name = String::from_utf8(name_raw.to_vec()).expect("Failed to parse name string.");
         let mut data = vec![0u8; length as usize];
-        let _ = self.reader.read(&mut data);
+        let _ = self.reader.read_exact(&mut data)?;
         let mut crc_raw = [0u8; 4];
-        let _ = self.reader.read(&mut crc_raw);
+        let _ = self.reader.read_exact(&mut crc_raw)?;
         let crc = BigEndian::read_u32(&mut crc_raw);
 
-        GenericChunk {
+        Ok(GenericChunk {
             length,
             name,
             data,
             crc,
-        }
+        })
     }
 }
 
-impl GenericChunk {
-    fn as_meta_chunk(&self) -> MetaChunk {
-        let mut chunk_count_raw = self.data[0..4].to_vec();
-        let mut entries_per_chunk = self.data[4..8].to_vec();
-        let mut total_number_of_entries = self.data[8..12].to_vec();
-        let mut compression_method_raw = self.data[12..16].to_vec();
-        let chunk_count = BigEndian::read_u32(&mut chunk_count_raw);
-        let entries_per_chunk = BigEndian::read_u32(&mut entries_per_chunk);
-        let entry_count = BigEndian::read_u32(&mut total_number_of_entries);
+impl TryFrom<GenericChunk> for MetaChunk {
+    type Error = Error;
+
+    fn try_from(chunk: GenericChunk) -> Result<MetaChunk, Error> {
+        if &chunk.name != HTBL_CHUNK_NAME {
+            return Err(Error::new(
+                ErrorKind::InvalidData,
+                "chunk name doesn't match",
+            ));
+        }
+        if chunk.data.len() < 16 {
+            return Err(Error::new(ErrorKind::InvalidData, "invalid chunk data"));
+        }
+        let chunk_count_raw = &chunk.data[0..4];
+        let entries_per_chunk = &chunk.data[4..8];
+        let total_number_of_entries = &chunk.data[8..12];
+        let compression_method_raw = chunk.data[12..16].to_vec();
+        let chunk_count = BigEndian::read_u32(chunk_count_raw);
+        let entries_per_chunk = BigEndian::read_u32(entries_per_chunk);
+        let entry_count = BigEndian::read_u32(total_number_of_entries);
         let compression_method = if &compression_method_raw != NULL_BYTES {
             Some(
-                String::from_utf8(compression_method_raw.to_vec())
-                    .expect("Failed to parse compression method from meta string"),
+                String::from_utf8(compression_method_raw)
+                    .expect("Failed to parse compression method name!"),
             )
         } else {
             None
         };
 
-        MetaChunk {
+        Ok(MetaChunk {
             chunk_count,
             entries_per_chunk,
             entry_count,
             compression_method,
+        })
+    }
+}
+
+impl HashLookupTable {
+    pub fn get_entry(&self, id: u32) -> Option<&HashEntry> {
+        self.entries.get(&id)
+    }
+}
+
+impl TryFrom<GenericChunk> for HashLookupTable {
+    type Error = Error;
+
+    fn try_from(chunk: GenericChunk) -> Result<HashLookupTable, Error> {
+        if &chunk.name != HTBL_CHUNK_NAME {
+            return Err(Error::new(
+                ErrorKind::InvalidData,
+                "chunk name doesn't match",
+            ));
+        }
+        let mut hash_entries: HashMap<u32, HashEntry> = HashMap::new();
+        let mut position = 0;
+        while chunk.data.len() > (position + 12) {
+            let id_raw = &chunk.data[position..position + 4];
+            position += 4;
+            let output_length_raw = &chunk.data[position..position + 4];
+            position += 4;
+            let name_length_raw = &chunk.data[position..position + 4];
+            position += 4;
+            let id = BigEndian::read_u32(id_raw);
+            let output_length = BigEndian::read_u32(output_length_raw);
+            let name_length = BigEndian::read_u32(name_length_raw);
+            let name_raw = &chunk.data[position..position + name_length as usize];
+            let name =
+                String::from_utf8(name_raw.to_vec()).expect("Failed to parse hash function name!");
+            hash_entries.insert(
+                id,
+                HashEntry {
+                    id,
+                    output_length,
+                    name,
+                },
+            );
         }
+        Ok(HashLookupTable {
+            entries: hash_entries,
+        })
     }
 }