feat: Take the size into account for Block reading, to handle missing fields

crates/fsv/src/fsv_parsing/blocks.rs

@@ -1,6 +1,6 @@
 use deku::deku_derive;
 
-use super::{ groups, size_read };
+use super::{ groups, size_read, read_with_size };
 
 #[derive(Debug, PartialEq)]
 #[deku_derive(DekuRead)]
@@ -19,7 +19,7 @@ pub struct Data {
 /// The `DataBlock` are the main structures inside a `Data` struct
 pub struct DataBlock {
     pub header: BlockHeader,
-    #[deku(ctx = "header.group_id.0")]
+    #[deku(ctx = "header.group_id.0, header.data_size")]
     pub content: DataGroup,
 }
 
@@ -32,7 +32,7 @@ pub struct BlockHeader {
 
     pub group_id: GroupId,
     #[deku(reader = "size_read(deku::reader)")]
-    pub data_size: u64, // This field is not really used, but we have to parse it to move the reader cursor
+    pub data_size: u64,
 }
 
 #[derive(Debug, PartialEq)]
@@ -51,19 +51,29 @@ pub struct GroupId(
 /// correct data structure, able to parse the data contained in
 #[derive(Debug, PartialEq)]
 #[deku_derive(DekuRead)]
-#[deku(ctx = "group_id: u16", id = "group_id")]
+#[deku(ctx = "group_id: u16, data_size: u64", id = "group_id")]
 #[allow(non_camel_case_types)]
 pub enum DataGroup {
     #[deku(id = 1)]
-    LireCartePS_Group1_Holder(groups::ssv_lire_carte_ps::group_1_holder::Holder),
+    LireCartePS_Group1_Holder(
+        #[deku(reader = "read_with_size(deku::reader, data_size as usize)")]
+        groups::ssv_lire_carte_ps::group_1_holder::Holder),
     #[deku(id = 60)]
-    LireConfig_Group60_ConfigHeader(groups::ssv_lire_config::group_60_header_config::ConfigHeader),
+    LireConfig_Group60_ConfigHeader(
+        #[deku(reader = "read_with_size(deku::reader, data_size as usize)")]
+        groups::ssv_lire_config::group_60_header_config::ConfigHeader),
     #[deku(id = 61)]
-    LireConfig_Group61_ReaderConfig(groups::ssv_lire_config::group_61_reader_config::ReaderConfig),
+    LireConfig_Group61_ReaderConfig(
+        #[deku(reader = "read_with_size(deku::reader, data_size as usize)")]
+        groups::ssv_lire_config::group_61_reader_config::ReaderConfig),
     #[deku(id = 64)]
-    LireConfig_Group64_SVComponentsConfig(groups::ssv_lire_config::group_64_sv_config::SVComponentsConfig),
+    LireConfig_Group64_SVComponentsConfig(
+        #[deku(reader = "read_with_size(deku::reader, data_size as usize)")]
+        groups::ssv_lire_config::group_64_sv_config::SVComponentsConfig),
     #[deku(id = 67)]
-    LireConfig_Group67_PCSCReaderConfig(groups::ssv_lire_config::group_67_pcsc_config::PCSCReaderConfig),
+    LireConfig_Group67_PCSCReaderConfig(
+        #[deku(reader = "read_with_size(deku::reader, data_size as usize)")]
+        groups::ssv_lire_config::group_67_pcsc_config::PCSCReaderConfig),
 }
 
 #[cfg(test)]
@@ -221,5 +231,4 @@ mod tests {
         let (_rest, val) = deku_testing::DekuTestWithGroupId::from_bytes((buffer, 0)).unwrap();
         assert_eq!(val.group_id.0, 1910, "EX2: ID");
     }
-
 }

crates/fsv/src/fsv_parsing/mod.rs

@@ -33,6 +33,26 @@ fn size_read<R: std::io::Read + std::io::Seek>(reader: &mut Reader<R>) -> Result
     Ok(size)
 }
 
+/// Deku Reader taking an expected size into account
+/// This function limit the reading to the size given in input
+fn read_with_size<T, R: std::io::Read + std::io::Seek>(
+    reader: &mut Reader<R>,
+    size: usize
+) -> Result<T, DekuError> 
+    where T: for<'a> DekuContainerRead<'a>
+{
+    let max_size = core::mem::size_of::<T>();
+    let mut buf = vec![0; max_size];
+    let buf: &mut [u8] = &mut buf;
+    let ret = reader.read_bytes(size, buf)?;
+    let (_rest, block) = match ret {
+        ReaderRet::Bytes => {
+            T::from_bytes((buf, 0))?
+        },
+        _ => return Err(DekuError::Parse("Unexpected result reading size bytes: got bits".into())),
+    };
+    Ok(block)
+}
 
 /// # Map bytes to a lossy string
 /// This function is used to map bytes to a string, ignoring invalid UTF-8 characters
@@ -43,3 +63,70 @@ fn map_bytes_to_lossy_string(data: &[u8]) -> Result<String, DekuError> {
     let version: String = String::from_utf8_lossy(data).to_string();
     Ok(version)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_read_with_size_reader() {
+        #[derive(Debug, PartialEq)]
+        #[deku_derive(DekuRead)]
+        struct Data {
+            #[deku(read_all)]
+            pub blocks: Vec<Block>,
+        }
+        #[derive(Debug, PartialEq)]
+        #[deku_derive(DekuRead)]
+        struct Block {
+            pub size: u8,
+            pub id: u8,
+            #[deku(ctx = "*id,*size-1")] // size-1 to remove the ID size
+            pub data: BlockType,
+        }
+        #[derive(Debug, PartialEq)]
+        #[deku_derive(DekuRead)]
+        #[deku(ctx = "id: u8, size: u8", id = "id")]
+        enum BlockType {
+            #[deku(id = 1)]
+            Block1(
+                #[deku(reader = "read_with_size(deku::reader, size as usize)")]
+                Block1
+            ),
+            #[deku(id = 2)]
+            Block2(
+                #[deku(reader = "read_with_size(deku::reader, size as usize)")]
+                Block2
+            ),
+        }
+        #[derive(Debug, PartialEq)]
+        #[deku_derive(DekuRead)]
+        struct Block1 {
+            pub field1_size: u8,
+            pub field1: u16,
+            pub field2_size: u8,
+            pub field2: u64,
+        }
+        #[derive(Debug, PartialEq)]
+        #[deku_derive(DekuRead)]
+        struct Block2;
+
+        let buffer = &[
+            // 1st Block, type 1
+            4, // Size: 4
+                1, // ID: 1
+                    2, 0x12, 0x34, // Field 1, size 2
+                    // No Field 2
+            // 2nd Block, type 1
+            6, // Size: Y
+                1, // ID: 2
+                    1, 0x56, // Field 1, size 1 (casted into u16)
+                    2, 0x78, 0x9A // Field 2, size 2
+        ];
+
+        let (_rest, val) = Data::from_bytes((buffer, 0)).unwrap();
+        assert_eq!(val.blocks.len(), 2);
+        assert_eq!(val.blocks[0].size, 4);
+        assert_eq!(val.blocks[1].size, 6);
+    }
+}