feat: add initial implementation of rsli crate

- Created Cargo.toml for the rsli crate with flate2 dependency.
- Implemented ResourceData enum for handling borrowed and owned byte slices.
- Added OutputBuffer trait and its Vec<u8> implementation for writing data.
- Defined a comprehensive Error enum for error handling in the library.
- Developed the Library struct to manage resource entries and provide methods for loading and unpacking resources.
- Implemented various packing methods and decompression algorithms, including LZSS and Deflate.
- Added tests for validating the functionality of the rsli library against sample data.

crates/nres/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "nres"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

crates/nres/src/data.rs

@@ -0,0 +1,43 @@
+use std::io;
+
+/// Resource payload that can be either borrowed from mapped bytes or owned.
+#[derive(Clone, Debug)]
+pub enum ResourceData<'a> {
+    Borrowed(&'a [u8]),
+    Owned(Vec<u8>),
+}
+
+impl<'a> ResourceData<'a> {
+    pub fn as_slice(&self) -> &[u8] {
+        match self {
+            Self::Borrowed(slice) => slice,
+            Self::Owned(buf) => buf.as_slice(),
+        }
+    }
+
+    pub fn into_owned(self) -> Vec<u8> {
+        match self {
+            Self::Borrowed(slice) => slice.to_vec(),
+            Self::Owned(buf) => buf,
+        }
+    }
+}
+
+impl AsRef<[u8]> for ResourceData<'_> {
+    fn as_ref(&self) -> &[u8] {
+        self.as_slice()
+    }
+}
+
+/// Output sink used by `read_into`/`load_into` APIs.
+pub trait OutputBuffer {
+    fn write_exact(&mut self, data: &[u8]) -> io::Result<()>;
+}
+
+impl OutputBuffer for Vec<u8> {
+    fn write_exact(&mut self, data: &[u8]) -> io::Result<()> {
+        self.clear();
+        self.extend_from_slice(data);
+        Ok(())
+    }
+}

crates/nres/src/error.rs

@@ -0,0 +1,99 @@
+use core::fmt;
+
+#[derive(Debug)]
+#[non_exhaustive]
+pub enum Error {
+    Io(std::io::Error),
+
+    InvalidMagic {
+        got: [u8; 4],
+    },
+    UnsupportedVersion {
+        got: u32,
+    },
+    TotalSizeMismatch {
+        header: u32,
+        actual: u64,
+    },
+
+    InvalidEntryCount {
+        got: i32,
+    },
+    DirectoryOutOfBounds {
+        directory_offset: u64,
+        directory_len: u64,
+        file_len: u64,
+    },
+
+    EntryIdOutOfRange {
+        id: u32,
+        entry_count: u32,
+    },
+    EntryDataOutOfBounds {
+        id: u32,
+        offset: u64,
+        size: u32,
+        directory_offset: u64,
+    },
+    NameTooLong {
+        got: usize,
+        max: usize,
+    },
+    NameContainsNul,
+    BadNameEncoding,
+
+    IntegerOverflow,
+
+    RawModeDisallowsOperation(&'static str),
+}
+
+impl From<std::io::Error> for Error {
+    fn from(value: std::io::Error) -> Self {
+        Self::Io(value)
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::Io(e) => write!(f, "I/O error: {e}"),
+            Error::InvalidMagic { got } => write!(f, "invalid NRes magic: {got:02X?}"),
+            Error::UnsupportedVersion { got } => {
+                write!(f, "unsupported NRes version: {got:#x}")
+            }
+            Error::TotalSizeMismatch { header, actual } => {
+                write!(f, "NRes total_size mismatch: header={header}, actual={actual}")
+            }
+            Error::InvalidEntryCount { got } => write!(f, "invalid entry_count: {got}"),
+            Error::DirectoryOutOfBounds {
+                directory_offset,
+                directory_len,
+                file_len,
+            } => write!(
+                f,
+                "directory out of bounds: off={directory_offset}, len={directory_len}, file={file_len}"
+            ),
+            Error::EntryIdOutOfRange { id, entry_count } => {
+                write!(f, "entry id out of range: id={id}, count={entry_count}")
+            }
+            Error::EntryDataOutOfBounds {
+                id,
+                offset,
+                size,
+                directory_offset,
+            } => write!(
+                f,
+                "entry data out of bounds: id={id}, off={offset}, size={size}, dir_off={directory_offset}"
+            ),
+            Error::NameTooLong { got, max } => write!(f, "name too long: {got} > {max}"),
+            Error::NameContainsNul => write!(f, "name contains NUL byte"),
+            Error::BadNameEncoding => write!(f, "bad name encoding"),
+            Error::IntegerOverflow => write!(f, "integer overflow"),
+            Error::RawModeDisallowsOperation(op) => {
+                write!(f, "operation not allowed in raw mode: {op}")
+            }
+        }
+    }
+}
+
+impl std::error::Error for Error {}

crates/nres/src/lib.rs

@@ -0,0 +1,863 @@
+pub mod data;
+pub mod error;
+
+use crate::data::{OutputBuffer, ResourceData};
+use crate::error::Error;
+use core::ops::Range;
+use std::cmp::Ordering;
+use std::fs::{self, OpenOptions as FsOpenOptions};
+use std::io::Write;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+pub type Result<T> = core::result::Result<T, Error>;
+
+#[derive(Clone, Debug, Default)]
+pub struct OpenOptions {
+    pub raw_mode: bool,
+    pub sequential_hint: bool,
+    pub prefetch_pages: bool,
+}
+
+#[derive(Clone, Debug)]
+pub enum OpenMode {
+    ReadOnly,
+    ReadWrite,
+}
+
+impl Default for OpenMode {
+    fn default() -> Self {
+        Self::ReadOnly
+    }
+}
+
+pub struct Archive {
+    bytes: Arc<[u8]>,
+    entries: Vec<EntryRecord>,
+    raw_mode: bool,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+pub struct EntryId(pub u32);
+
+#[derive(Clone, Debug)]
+pub struct EntryMeta {
+    pub kind: u32,
+    pub attr1: u32,
+    pub attr2: u32,
+    pub attr3: u32,
+    pub name: String,
+    pub data_offset: u64,
+    pub data_size: u32,
+    pub sort_index: u32,
+}
+
+#[derive(Copy, Clone, Debug)]
+pub struct EntryRef<'a> {
+    pub id: EntryId,
+    pub meta: &'a EntryMeta,
+}
+
+#[derive(Clone, Debug)]
+struct EntryRecord {
+    meta: EntryMeta,
+    name_raw: [u8; 36],
+}
+
+impl Archive {
+    pub fn open_path(path: impl AsRef<Path>) -> Result<Self> {
+        Self::open_path_with(path, OpenMode::ReadOnly, OpenOptions::default())
+    }
+
+    pub fn open_path_with(
+        path: impl AsRef<Path>,
+        _mode: OpenMode,
+        opts: OpenOptions,
+    ) -> Result<Self> {
+        let bytes = fs::read(path.as_ref())?;
+        let arc: Arc<[u8]> = Arc::from(bytes.into_boxed_slice());
+        Self::open_bytes(arc, opts)
+    }
+
+    pub fn open_bytes(bytes: Arc<[u8]>, opts: OpenOptions) -> Result<Self> {
+        let (entries, _) = parse_archive(&bytes, opts.raw_mode)?;
+        if opts.prefetch_pages {
+            prefetch_pages(&bytes);
+        }
+        Ok(Self {
+            bytes,
+            entries,
+            raw_mode: opts.raw_mode,
+        })
+    }
+
+    pub fn entry_count(&self) -> usize {
+        self.entries.len()
+    }
+
+    pub fn entries(&self) -> impl Iterator<Item = EntryRef<'_>> {
+        self.entries
+            .iter()
+            .enumerate()
+            .map(|(idx, entry)| EntryRef {
+                id: EntryId(idx as u32),
+                meta: &entry.meta,
+            })
+    }
+
+    pub fn find(&self, name: &str) -> Option<EntryId> {
+        if self.entries.is_empty() {
+            return None;
+        }
+
+        if !self.raw_mode {
+            let mut low = 0usize;
+            let mut high = self.entries.len();
+            while low < high {
+                let mid = low + (high - low) / 2;
+                let target_idx = self.entries[mid].meta.sort_index as usize;
+                if target_idx >= self.entries.len() {
+                    break;
+                }
+                let cmp = cmp_name_case_insensitive(
+                    name.as_bytes(),
+                    entry_name_bytes(&self.entries[target_idx].name_raw),
+                );
+                match cmp {
+                    Ordering::Less => high = mid,
+                    Ordering::Greater => low = mid + 1,
+                    Ordering::Equal => return Some(EntryId(target_idx as u32)),
+                }
+            }
+        }
+
+        self.entries.iter().enumerate().find_map(|(idx, entry)| {
+            if cmp_name_case_insensitive(name.as_bytes(), entry_name_bytes(&entry.name_raw))
+                == Ordering::Equal
+            {
+                Some(EntryId(idx as u32))
+            } else {
+                None
+            }
+        })
+    }
+
+    pub fn get(&self, id: EntryId) -> Option<EntryRef<'_>> {
+        let idx = usize::try_from(id.0).ok()?;
+        let entry = self.entries.get(idx)?;
+        Some(EntryRef {
+            id,
+            meta: &entry.meta,
+        })
+    }
+
+    pub fn read(&self, id: EntryId) -> Result<ResourceData<'_>> {
+        let range = self.entry_range(id)?;
+        Ok(ResourceData::Borrowed(&self.bytes[range]))
+    }
+
+    pub fn read_into(&self, id: EntryId, out: &mut dyn OutputBuffer) -> Result<usize> {
+        let range = self.entry_range(id)?;
+        out.write_exact(&self.bytes[range.clone()])?;
+        Ok(range.len())
+    }
+
+    pub fn raw_slice(&self, id: EntryId) -> Result<Option<&[u8]>> {
+        let range = self.entry_range(id)?;
+        Ok(Some(&self.bytes[range]))
+    }
+
+    pub fn edit_path(path: impl AsRef<Path>) -> Result<Editor> {
+        let path_buf = path.as_ref().to_path_buf();
+        let bytes = fs::read(&path_buf)?;
+        let arc: Arc<[u8]> = Arc::from(bytes.into_boxed_slice());
+        let (entries, _) = parse_archive(&arc, false)?;
+        let mut editable = Vec::with_capacity(entries.len());
+        for entry in &entries {
+            let range = checked_range(entry.meta.data_offset, entry.meta.data_size, arc.len())?;
+            editable.push(EditableEntry {
+                meta: entry.meta.clone(),
+                name_raw: entry.name_raw,
+                data: arc[range].to_vec(),
+            });
+        }
+        Ok(Editor {
+            path: path_buf,
+            entries: editable,
+        })
+    }
+
+    fn entry_range(&self, id: EntryId) -> Result<Range<usize>> {
+        let idx = usize::try_from(id.0).map_err(|_| Error::IntegerOverflow)?;
+        let Some(entry) = self.entries.get(idx) else {
+            return Err(Error::EntryIdOutOfRange {
+                id: id.0,
+                entry_count: self.entries.len().try_into().unwrap_or(u32::MAX),
+            });
+        };
+        checked_range(
+            entry.meta.data_offset,
+            entry.meta.data_size,
+            self.bytes.len(),
+        )
+    }
+}
+
+pub struct Editor {
+    path: PathBuf,
+    entries: Vec<EditableEntry>,
+}
+
+#[derive(Clone, Debug)]
+struct EditableEntry {
+    meta: EntryMeta,
+    name_raw: [u8; 36],
+    data: Vec<u8>,
+}
+
+#[derive(Clone, Debug)]
+pub struct NewEntry<'a> {
+    pub kind: u32,
+    pub attr1: u32,
+    pub attr2: u32,
+    pub attr3: u32,
+    pub name: &'a str,
+    pub data: &'a [u8],
+}
+
+impl Editor {
+    pub fn entries(&self) -> impl Iterator<Item = EntryRef<'_>> {
+        self.entries
+            .iter()
+            .enumerate()
+            .map(|(idx, entry)| EntryRef {
+                id: EntryId(idx as u32),
+                meta: &entry.meta,
+            })
+    }
+
+    pub fn add(&mut self, entry: NewEntry<'_>) -> Result<EntryId> {
+        let name_raw = encode_name_field(entry.name)?;
+        let id_u32 = u32::try_from(self.entries.len()).map_err(|_| Error::IntegerOverflow)?;
+        let data_size = u32::try_from(entry.data.len()).map_err(|_| Error::IntegerOverflow)?;
+        self.entries.push(EditableEntry {
+            meta: EntryMeta {
+                kind: entry.kind,
+                attr1: entry.attr1,
+                attr2: entry.attr2,
+                attr3: entry.attr3,
+                name: decode_name(entry_name_bytes(&name_raw)),
+                data_offset: 0,
+                data_size,
+                sort_index: 0,
+            },
+            name_raw,
+            data: entry.data.to_vec(),
+        });
+        Ok(EntryId(id_u32))
+    }
+
+    pub fn replace_data(&mut self, id: EntryId, data: &[u8]) -> Result<()> {
+        let idx = usize::try_from(id.0).map_err(|_| Error::IntegerOverflow)?;
+        let Some(entry) = self.entries.get_mut(idx) else {
+            return Err(Error::EntryIdOutOfRange {
+                id: id.0,
+                entry_count: self.entries.len().try_into().unwrap_or(u32::MAX),
+            });
+        };
+        entry.meta.data_size = u32::try_from(data.len()).map_err(|_| Error::IntegerOverflow)?;
+        entry.data.clear();
+        entry.data.extend_from_slice(data);
+        Ok(())
+    }
+
+    pub fn remove(&mut self, id: EntryId) -> Result<()> {
+        let idx = usize::try_from(id.0).map_err(|_| Error::IntegerOverflow)?;
+        if idx >= self.entries.len() {
+            return Err(Error::EntryIdOutOfRange {
+                id: id.0,
+                entry_count: self.entries.len().try_into().unwrap_or(u32::MAX),
+            });
+        }
+        self.entries.remove(idx);
+        Ok(())
+    }
+
+    pub fn commit(mut self) -> Result<()> {
+        let count_u32 = u32::try_from(self.entries.len()).map_err(|_| Error::IntegerOverflow)?;
+        let mut out = Vec::new();
+        out.resize(16, 0);
+
+        for entry in &mut self.entries {
+            entry.meta.data_offset =
+                u64::try_from(out.len()).map_err(|_| Error::IntegerOverflow)?;
+            entry.meta.data_size =
+                u32::try_from(entry.data.len()).map_err(|_| Error::IntegerOverflow)?;
+            out.extend_from_slice(&entry.data);
+            let padding = (8 - (out.len() % 8)) % 8;
+            if padding > 0 {
+                out.resize(out.len() + padding, 0);
+            }
+        }
+
+        let mut sort_order: Vec<usize> = (0..self.entries.len()).collect();
+        sort_order.sort_by(|a, b| {
+            cmp_name_case_insensitive(
+                entry_name_bytes(&self.entries[*a].name_raw),
+                entry_name_bytes(&self.entries[*b].name_raw),
+            )
+        });
+
+        for (idx, entry) in self.entries.iter_mut().enumerate() {
+            entry.meta.sort_index =
+                u32::try_from(sort_order[idx]).map_err(|_| Error::IntegerOverflow)?;
+        }
+
+        for entry in &self.entries {
+            let data_offset_u32 =
+                u32::try_from(entry.meta.data_offset).map_err(|_| Error::IntegerOverflow)?;
+            push_u32(&mut out, entry.meta.kind);
+            push_u32(&mut out, entry.meta.attr1);
+            push_u32(&mut out, entry.meta.attr2);
+            push_u32(&mut out, entry.meta.data_size);
+            push_u32(&mut out, entry.meta.attr3);
+            out.extend_from_slice(&entry.name_raw);
+            push_u32(&mut out, data_offset_u32);
+            push_u32(&mut out, entry.meta.sort_index);
+        }
+
+        let total_size_u32 = u32::try_from(out.len()).map_err(|_| Error::IntegerOverflow)?;
+        out[0..4].copy_from_slice(b"NRes");
+        out[4..8].copy_from_slice(&0x100_u32.to_le_bytes());
+        out[8..12].copy_from_slice(&count_u32.to_le_bytes());
+        out[12..16].copy_from_slice(&total_size_u32.to_le_bytes());
+
+        write_atomic(&self.path, &out)
+    }
+}
+
+fn parse_archive(bytes: &[u8], raw_mode: bool) -> Result<(Vec<EntryRecord>, u64)> {
+    if raw_mode {
+        let data_size = u32::try_from(bytes.len()).map_err(|_| Error::IntegerOverflow)?;
+        let entry = EntryRecord {
+            meta: EntryMeta {
+                kind: 0,
+                attr1: 0,
+                attr2: 0,
+                attr3: 0,
+                name: String::from("RAW"),
+                data_offset: 0,
+                data_size,
+                sort_index: 0,
+            },
+            name_raw: {
+                let mut name = [0u8; 36];
+                let bytes_name = b"RAW";
+                name[..bytes_name.len()].copy_from_slice(bytes_name);
+                name
+            },
+        };
+        return Ok((vec![entry], bytes.len() as u64));
+    }
+
+    if bytes.len() < 16 {
+        let mut got = [0u8; 4];
+        let copy_len = bytes.len().min(4);
+        got[..copy_len].copy_from_slice(&bytes[..copy_len]);
+        return Err(Error::InvalidMagic { got });
+    }
+
+    let mut magic = [0u8; 4];
+    magic.copy_from_slice(&bytes[0..4]);
+    if &magic != b"NRes" {
+        return Err(Error::InvalidMagic { got: magic });
+    }
+
+    let version = read_u32(bytes, 4)?;
+    if version != 0x100 {
+        return Err(Error::UnsupportedVersion { got: version });
+    }
+
+    let entry_count_i32 = i32::from_le_bytes(
+        bytes[8..12]
+            .try_into()
+            .map_err(|_| Error::IntegerOverflow)?,
+    );
+    if entry_count_i32 < 0 {
+        return Err(Error::InvalidEntryCount {
+            got: entry_count_i32,
+        });
+    }
+    let entry_count = usize::try_from(entry_count_i32).map_err(|_| Error::IntegerOverflow)?;
+
+    let total_size = read_u32(bytes, 12)?;
+    let actual_size = u64::try_from(bytes.len()).map_err(|_| Error::IntegerOverflow)?;
+    if u64::from(total_size) != actual_size {
+        return Err(Error::TotalSizeMismatch {
+            header: total_size,
+            actual: actual_size,
+        });
+    }
+
+    let directory_len = u64::try_from(entry_count)
+        .map_err(|_| Error::IntegerOverflow)?
+        .checked_mul(64)
+        .ok_or(Error::IntegerOverflow)?;
+    let directory_offset =
+        u64::from(total_size)
+            .checked_sub(directory_len)
+            .ok_or(Error::DirectoryOutOfBounds {
+                directory_offset: 0,
+                directory_len,
+                file_len: actual_size,
+            })?;
+
+    if directory_offset < 16 || directory_offset + directory_len > actual_size {
+        return Err(Error::DirectoryOutOfBounds {
+            directory_offset,
+            directory_len,
+            file_len: actual_size,
+        });
+    }
+
+    let mut entries = Vec::with_capacity(entry_count);
+    for index in 0..entry_count {
+        let base = usize::try_from(directory_offset)
+            .map_err(|_| Error::IntegerOverflow)?
+            .checked_add(index.checked_mul(64).ok_or(Error::IntegerOverflow)?)
+            .ok_or(Error::IntegerOverflow)?;
+
+        let kind = read_u32(bytes, base)?;
+        let attr1 = read_u32(bytes, base + 4)?;
+        let attr2 = read_u32(bytes, base + 8)?;
+        let data_size = read_u32(bytes, base + 12)?;
+        let attr3 = read_u32(bytes, base + 16)?;
+
+        let mut name_raw = [0u8; 36];
+        let name_slice = bytes
+            .get(base + 20..base + 56)
+            .ok_or(Error::IntegerOverflow)?;
+        name_raw.copy_from_slice(name_slice);
+
+        let name_bytes = entry_name_bytes(&name_raw);
+        if name_bytes.len() > 35 {
+            return Err(Error::NameTooLong {
+                got: name_bytes.len(),
+                max: 35,
+            });
+        }
+
+        let data_offset = u64::from(read_u32(bytes, base + 56)?);
+        let sort_index = read_u32(bytes, base + 60)?;
+
+        let end = data_offset
+            .checked_add(u64::from(data_size))
+            .ok_or(Error::IntegerOverflow)?;
+        if data_offset < 16 || end > directory_offset {
+            return Err(Error::EntryDataOutOfBounds {
+                id: u32::try_from(index).map_err(|_| Error::IntegerOverflow)?,
+                offset: data_offset,
+                size: data_size,
+                directory_offset,
+            });
+        }
+
+        entries.push(EntryRecord {
+            meta: EntryMeta {
+                kind,
+                attr1,
+                attr2,
+                attr3,
+                name: decode_name(name_bytes),
+                data_offset,
+                data_size,
+                sort_index,
+            },
+            name_raw,
+        });
+    }
+
+    Ok((entries, directory_offset))
+}
+
+fn checked_range(offset: u64, size: u32, bytes_len: usize) -> Result<Range<usize>> {
+    let start = usize::try_from(offset).map_err(|_| Error::IntegerOverflow)?;
+    let len = usize::try_from(size).map_err(|_| Error::IntegerOverflow)?;
+    let end = start.checked_add(len).ok_or(Error::IntegerOverflow)?;
+    if end > bytes_len {
+        return Err(Error::IntegerOverflow);
+    }
+    Ok(start..end)
+}
+
+fn read_u32(bytes: &[u8], offset: usize) -> Result<u32> {
+    let data = bytes
+        .get(offset..offset + 4)
+        .ok_or(Error::IntegerOverflow)?;
+    let arr: [u8; 4] = data.try_into().map_err(|_| Error::IntegerOverflow)?;
+    Ok(u32::from_le_bytes(arr))
+}
+
+fn push_u32(out: &mut Vec<u8>, value: u32) {
+    out.extend_from_slice(&value.to_le_bytes());
+}
+
+fn encode_name_field(name: &str) -> Result<[u8; 36]> {
+    let bytes = name.as_bytes();
+    if bytes.contains(&0) {
+        return Err(Error::NameContainsNul);
+    }
+    if bytes.len() > 35 {
+        return Err(Error::NameTooLong {
+            got: bytes.len(),
+            max: 35,
+        });
+    }
+
+    let mut out = [0u8; 36];
+    out[..bytes.len()].copy_from_slice(bytes);
+    Ok(out)
+}
+
+fn entry_name_bytes(raw: &[u8; 36]) -> &[u8] {
+    let len = raw.iter().position(|&b| b == 0).unwrap_or(raw.len());
+    &raw[..len]
+}
+
+fn decode_name(name: &[u8]) -> String {
+    name.iter().map(|b| char::from(*b)).collect()
+}
+
+fn cmp_name_case_insensitive(a: &[u8], b: &[u8]) -> Ordering {
+    let mut idx = 0usize;
+    let min_len = a.len().min(b.len());
+    while idx < min_len {
+        let left = ascii_lower(a[idx]);
+        let right = ascii_lower(b[idx]);
+        if left != right {
+            return left.cmp(&right);
+        }
+        idx += 1;
+    }
+    a.len().cmp(&b.len())
+}
+
+fn ascii_lower(value: u8) -> u8 {
+    if value.is_ascii_uppercase() {
+        value + 32
+    } else {
+        value
+    }
+}
+
+fn prefetch_pages(bytes: &[u8]) {
+    use std::sync::atomic::{compiler_fence, Ordering};
+
+    let mut cursor = 0usize;
+    let mut sink = 0u8;
+    while cursor < bytes.len() {
+        sink ^= bytes[cursor];
+        cursor = cursor.saturating_add(4096);
+    }
+    compiler_fence(Ordering::SeqCst);
+    let _ = sink;
+}
+
+fn write_atomic(path: &Path, content: &[u8]) -> Result<()> {
+    let file_name = path
+        .file_name()
+        .and_then(|name| name.to_str())
+        .unwrap_or("archive");
+    let parent = path.parent().unwrap_or_else(|| Path::new("."));
+
+    let mut temp_path = None;
+    for attempt in 0..128u32 {
+        let name = format!(
+            ".{}.tmp.{}.{}.{}",
+            file_name,
+            std::process::id(),
+            unix_time_nanos(),
+            attempt
+        );
+        let candidate = parent.join(name);
+        let opened = FsOpenOptions::new()
+            .create_new(true)
+            .write(true)
+            .open(&candidate);
+        if let Ok(mut file) = opened {
+            file.write_all(content)?;
+            file.sync_all()?;
+            temp_path = Some((candidate, file));
+            break;
+        }
+    }
+
+    let Some((tmp_path, mut file)) = temp_path else {
+        return Err(Error::Io(std::io::Error::new(
+            std::io::ErrorKind::AlreadyExists,
+            "failed to create temporary file for atomic write",
+        )));
+    };
+
+    file.flush()?;
+    drop(file);
+
+    match fs::rename(&tmp_path, path) {
+        Ok(()) => Ok(()),
+        Err(rename_err) => {
+            if path.exists() {
+                fs::remove_file(path)?;
+                fs::rename(&tmp_path, path)?;
+                Ok(())
+            } else {
+                let _ = fs::remove_file(&tmp_path);
+                Err(Error::Io(rename_err))
+            }
+        }
+    }
+}
+
+fn unix_time_nanos() -> u128 {
+    match SystemTime::now().duration_since(UNIX_EPOCH) {
+        Ok(duration) => duration.as_nanos(),
+        Err(_) => 0,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::any::Any;
+    use std::fs;
+    use std::panic::{catch_unwind, AssertUnwindSafe};
+
+    fn collect_files_recursive(root: &Path, out: &mut Vec<PathBuf>) {
+        let Ok(entries) = fs::read_dir(root) else {
+            return;
+        };
+        for entry in entries.flatten() {
+            let path = entry.path();
+            if path.is_dir() {
+                collect_files_recursive(&path, out);
+            } else if path.is_file() {
+                out.push(path);
+            }
+        }
+    }
+
+    fn nres_test_files() -> Vec<PathBuf> {
+        let root = Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("..")
+            .join("..")
+            .join("testdata")
+            .join("nres");
+        let mut files = Vec::new();
+        collect_files_recursive(&root, &mut files);
+        files.sort();
+        files
+            .into_iter()
+            .filter(|path| {
+                fs::read(path)
+                    .map(|data| data.get(0..4) == Some(b"NRes"))
+                    .unwrap_or(false)
+            })
+            .collect()
+    }
+
+    fn make_temp_copy(original: &Path, bytes: &[u8]) -> PathBuf {
+        let mut path = std::env::temp_dir();
+        let file_name = original
+            .file_name()
+            .and_then(|v| v.to_str())
+            .unwrap_or("archive");
+        path.push(format!(
+            "nres-test-{}-{}-{}",
+            std::process::id(),
+            unix_time_nanos(),
+            file_name
+        ));
+        fs::write(&path, bytes).expect("failed to create temp file");
+        path
+    }
+
+    fn panic_message(payload: Box<dyn Any + Send>) -> String {
+        let any = payload.as_ref();
+        if let Some(message) = any.downcast_ref::<String>() {
+            return message.clone();
+        }
+        if let Some(message) = any.downcast_ref::<&str>() {
+            return (*message).to_string();
+        }
+        String::from("panic without message")
+    }
+
+    #[test]
+    fn nres_read_and_roundtrip_all_files() {
+        let files = nres_test_files();
+        assert!(!files.is_empty(), "testdata/nres contains no NRes archives");
+
+        let checked = files.len();
+        let mut success = 0usize;
+        let mut failures = Vec::new();
+
+        for path in files {
+            let display_path = path.display().to_string();
+            let result = catch_unwind(AssertUnwindSafe(|| {
+                let original = fs::read(&path).expect("failed to read archive");
+                let archive = Archive::open_path(&path)
+                    .unwrap_or_else(|err| panic!("failed to open {}: {err}", path.display()));
+
+                let count = archive.entry_count();
+                assert_eq!(
+                    count,
+                    archive.entries().count(),
+                    "entry count mismatch: {}",
+                    path.display()
+                );
+
+                for idx in 0..count {
+                    let id = EntryId(idx as u32);
+                    let entry = archive
+                        .get(id)
+                        .unwrap_or_else(|| panic!("missing entry #{idx} in {}", path.display()));
+
+                    let payload = archive.read(id).unwrap_or_else(|err| {
+                        panic!("read failed for {} entry #{idx}: {err}", path.display())
+                    });
+
+                    let mut out = Vec::new();
+                    let written = archive.read_into(id, &mut out).unwrap_or_else(|err| {
+                        panic!(
+                            "read_into failed for {} entry #{idx}: {err}",
+                            path.display()
+                        )
+                    });
+                    assert_eq!(
+                        written,
+                        payload.as_slice().len(),
+                        "size mismatch in {} entry #{idx}",
+                        path.display()
+                    );
+                    assert_eq!(
+                        out.as_slice(),
+                        payload.as_slice(),
+                        "payload mismatch in {} entry #{idx}",
+                        path.display()
+                    );
+
+                    let raw = archive
+                        .raw_slice(id)
+                        .unwrap_or_else(|err| {
+                            panic!(
+                                "raw_slice failed for {} entry #{idx}: {err}",
+                                path.display()
+                            )
+                        })
+                        .expect("raw_slice must return Some for file-backed archive");
+                    assert_eq!(
+                        raw,
+                        payload.as_slice(),
+                        "raw slice mismatch in {} entry #{idx}",
+                        path.display()
+                    );
+
+                    let found = archive.find(&entry.meta.name).unwrap_or_else(|| {
+                        panic!(
+                            "find failed for name '{}' in {}",
+                            entry.meta.name,
+                            path.display()
+                        )
+                    });
+                    let found_meta = archive.get(found).expect("find returned invalid id");
+                    assert!(
+                        found_meta.meta.name.eq_ignore_ascii_case(&entry.meta.name),
+                        "find returned unrelated entry in {}",
+                        path.display()
+                    );
+                }
+
+                let temp_copy = make_temp_copy(&path, &original);
+                let mut editor = Archive::edit_path(&temp_copy)
+                    .unwrap_or_else(|err| panic!("edit_path failed for {}: {err}", path.display()));
+
+                for idx in 0..count {
+                    let data = archive
+                        .read(EntryId(idx as u32))
+                        .unwrap_or_else(|err| {
+                            panic!(
+                                "read before replace failed for {} entry #{idx}: {err}",
+                                path.display()
+                            )
+                        })
+                        .into_owned();
+                    editor
+                        .replace_data(EntryId(idx as u32), &data)
+                        .unwrap_or_else(|err| {
+                            panic!(
+                                "replace_data failed for {} entry #{idx}: {err}",
+                                path.display()
+                            )
+                        });
+                }
+
+                editor
+                    .commit()
+                    .unwrap_or_else(|err| panic!("commit failed for {}: {err}", path.display()));
+                let rebuilt = fs::read(&temp_copy).expect("failed to read rebuilt archive");
+                let _ = fs::remove_file(&temp_copy);
+
+                assert_eq!(
+                    original,
+                    rebuilt,
+                    "byte-to-byte roundtrip mismatch for {}",
+                    path.display()
+                );
+            }));
+
+            match result {
+                Ok(()) => success += 1,
+                Err(payload) => {
+                    failures.push(format!("{}: {}", display_path, panic_message(payload)));
+                }
+            }
+        }
+
+        let failed = failures.len();
+        eprintln!(
+            "NRes summary: checked={}, success={}, failed={}",
+            checked, success, failed
+        );
+        if !failures.is_empty() {
+            panic!(
+                "NRes validation failed.\nsummary: checked={}, success={}, failed={}\n{}",
+                checked,
+                success,
+                failed,
+                failures.join("\n")
+            );
+        }
+    }
+
+    #[test]
+    fn nres_raw_mode_exposes_whole_file() {
+        let files = nres_test_files();
+        let first = files.first().expect("testdata/nres has no archives");
+        let original = fs::read(first).expect("failed to read archive");
+        let arc: Arc<[u8]> = Arc::from(original.clone().into_boxed_slice());
+
+        let archive = Archive::open_bytes(
+            arc,
+            OpenOptions {
+                raw_mode: true,
+                sequential_hint: false,
+                prefetch_pages: false,
+            },
+        )
+        .expect("raw mode open failed");
+
+        assert_eq!(archive.entry_count(), 1);
+        let data = archive.read(EntryId(0)).expect("raw read failed");
+        assert_eq!(data.as_slice(), original.as_slice());
+    }
+}