Wrote/updated some TODOs, skeleton of generate_fragmentations

libsearchlight/src/utils.rs

@@ -2,9 +2,9 @@ pub mod iter;
 pub mod str_parse;
 pub mod fragments_index;
 
-use std::{collections::BTreeMap, fs::File, io::{self, Seek}};
+use std::{collections::BTreeMap, fs::File, io::{self, Seek}, ops::Range};
 
-use crate::search::Match;
+use crate::{search::Match, validation::Fragment};
 
 #[cfg(test)]
 pub fn init_test_logger() {
@@ -87,6 +87,13 @@ pub fn estimate_cluster_size<'a>(headers: impl IntoIterator<Item = &'a Match>) -
 	}
 }
 
+/// Generates a list of lists of fragments, as candidates for reconstructing fragmented data in `fragmentation_range`. That is, for fragmented data in
+/// `fragmentation_range`, occupying a known `num_file_clusters` clusters, and being broken into `num_fragments` fragments, this function will generate
+/// all possible arrangements of clusters that the fragmented data can occupy, assuming that the fragmented data is in-order.
+fn generate_fragmentations(file_data: &[u8], cluster_size: usize, fragmentation_range: Range<usize>, num_file_clusters: usize, num_fragments: usize) -> Vec<Vec<Fragment>> {
+	todo!() // TODO: Implement an algorithm to do as described in the doc comment. Look at https://doi.org/10.1016/j.diin.2019.04.014 for inspiration if need be
+}
+
 #[cfg(test)]
 mod test {
     use crate::{search::Match, utils::estimate_cluster_size};

libsearchlight/src/validation/png.rs

@@ -233,6 +233,8 @@ impl PngValidator {
 		// Load the (what we assume is) the CRC
 		let stored_crc = u32::from_be_bytes(file_data[(next_chunk_type_offset - 8)..(next_chunk_type_offset - 4)].try_into().unwrap());
 
+		// TODO: Check these below calculations
+
 		// Calculate the fragmentation points
 		let fragmentation_start = utils::next_multiple_of(chunk_idx as u64 + 8, cluster_size) as usize;
 		let fragmentation_end = utils::prev_multiple_of(next_chunk_type_offset as u64 - 8, cluster_size) as usize;
@@ -245,8 +247,10 @@ impl PngValidator {
 		assert_eq!((next_chunk_type_offset - (unfrag_crc_offset + 8)) % cluster_size as usize, 0);
 		assert_eq!((fragmentation_end - fragmentation_start) % cluster_size as usize, 0);
 
-		// TODO: We've found the next chunk type (hopefully). Now, decode the stored CRC, and find the arrangements of clusters from the fragmentation start point to this point
-		//       that result in the calculated CRC matching the decoded CRC
+		// TODO: Use utils::generate_fragmentations (once implemented) and calculate the CRC over each fragmentation (including data outside of the fragmentation
+		//       area, like the chunk type and data in the same cluster) to find one that matches the stored CRC. If none can be found, return a failure
+
+		// utils::generate_fragmentations
 
 		todo!()
 	}