Replace wrestool with native Rust PE icon extraction (pelite)

- Add icons.rs to nak crate: parses PE resource sections, extracts
  RT_GROUP_ICON/RT_ICON and builds ICO files in memory
- Expose nak_extract_exe_icon() FFI for C++ consumption
- Update iconForExecutable() to use Rust FFI instead of shelling out
  to wrestool; reads all ICO entries for correct color depth
- Fix BasicGamePlugin::gameIcon() to call iconForExecutable() (was
  returning empty QIcon, causing placeholder icons for BG3/Cyberpunk)
- Move app icon setup: setDesktopFileName + setWindowIcon to
  MOApplication constructor (fixes Wayland taskbar/decoration icon)
- Move data/com.fluorine.* to data/icons/, install to XDG paths at
  launch for Wayland compositor icon resolution
- Remove icoutils dependency from Docker image and build output

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2 files changed, 196 insertions, 0 deletions

diff --git a/libs/nak/src/icons.rs b/libs/nak/src/icons.rs
new file mode 100644
index 0000000..940d0d1
--- /dev/null
+++ b/libs/nak/src/icons.rs
@@ -0,0 +1,195 @@
+//! Extract icons from Windows PE (.exe/.dll) files using pelite.

+//!

+//! Returns raw ICO file bytes that can be loaded directly by Qt's QIcon/QImage.

+

+use std::path::Path;

+

+use pelite::resources::{Entry, Name, Resources};

+

+/// Extract the best (largest) icon from a PE executable as raw ICO bytes.

+///

+/// Returns `None` if the file can't be read, isn't a valid PE, or has no icons.

+pub fn extract_icon(exe_path: &Path) -> Option<Vec<u8>> {

+    let data = std::fs::read(exe_path).ok()?;

+

+    // Try PE32+ (64-bit) first, fall back to PE32 (32-bit)

+    if let Ok(icon) = extract_from_pe64(&data) {

+        return Some(icon);

+    }

+    if let Ok(icon) = extract_from_pe32(&data) {

+        return Some(icon);

+    }

+

+    None

+}

+

+fn extract_from_pe64(data: &[u8]) -> Result<Vec<u8>, Box<dyn std::error::Error>> {

+    use pelite::pe64::{Pe, PeFile};

+    let pe = PeFile::from_bytes(data)?;

+    let resources = pe.resources()?;

+    build_ico_from_resources(&resources)

+}

+

+fn extract_from_pe32(data: &[u8]) -> Result<Vec<u8>, Box<dyn std::error::Error>> {

+    use pelite::pe32::{Pe, PeFile};

+    let pe = PeFile::from_bytes(data)?;

+    let resources = pe.resources()?;

+    build_ico_from_resources(&resources)

+}

+

+/// Build an ICO file from PE resources, picking the group icon with the

+/// largest total pixel area.

+fn build_ico_from_resources(

+    resources: &Resources,

+) -> Result<Vec<u8>, Box<dyn std::error::Error>> {

+    let root = resources.root()?;

+

+    // Find RT_GROUP_ICON directory (type 14)

+    let group_icon_dir = root

+        .get_dir(Name::Id(14))

+        .map_err(|_| "no RT_GROUP_ICON")?;

+

+    let mut best_group: Option<(i32, Vec<u8>)> = None;

+

+    for dir_entry in group_icon_dir.entries() {

+        // Each entry is a group; get its subdirectory (language variants)

+        let sub_dir = match dir_entry.entry() {

+            Ok(Entry::Directory(d)) => d,

+            _ => continue,

+        };

+

+        // Get the first language variant's data

+        let data_entry = match sub_dir.entries().next() {

+            Some(e) => match e.entry() {

+                Ok(Entry::DataEntry(d)) => d,

+                _ => continue,

+            },

+            None => continue,

+        };

+

+        let grp_data = match data_entry.bytes() {

+            Ok(d) => d,

+            Err(_) => continue,

+        };

+

+        // Parse GRPICONDIR header: reserved(2) + type(2) + count(2) = 6 bytes

+        if grp_data.len() < 6 {

+            continue;

+        }

+        let count = u16::from_le_bytes([grp_data[4], grp_data[5]]) as usize;

+        // Each GRPICONDIRENTRY is 14 bytes

+        if grp_data.len() < 6 + count * 14 {

+            continue;

+        }

+

+        // Calculate total pixel area for ranking

+        let mut total_area: i32 = 0;

+        for i in 0..count {

+            let offset = 6 + i * 14;

+            let w = if grp_data[offset] == 0 {

+                256i32

+            } else {

+                grp_data[offset] as i32

+            };

+            let h = if grp_data[offset + 1] == 0 {

+                256i32

+            } else {

+                grp_data[offset + 1] as i32

+            };

+            total_area += w * h;

+        }

+

+        if let Ok(ico_bytes) = build_ico_file(resources, grp_data, count) {

+            if best_group.is_none() || total_area > best_group.as_ref().unwrap().0 {

+                best_group = Some((total_area, ico_bytes));

+            }

+        }

+    }

+

+    best_group

+        .map(|(_, bytes)| bytes)

+        .ok_or_else(|| "no valid icon group found".into())

+}

+

+/// Build a complete ICO file from a GRPICONDIR and the corresponding RT_ICON resources.

+fn build_ico_file(

+    resources: &Resources,

+    grp_data: &[u8],

+    count: usize,

+) -> Result<Vec<u8>, Box<dyn std::error::Error>> {

+    let root = resources.root()?;

+

+    // RT_ICON = type 3

+    let icon_dir = root.get_dir(Name::Id(3)).map_err(|_| "no RT_ICON")?;

+

+    // Collect individual icon image data

+    struct IconEntry<'a> {

+        header: [u8; 8], // first 8 bytes of GRPICONDIRENTRY (w, h, colors, reserved, planes, bpp)

+        data: &'a [u8],

+    }

+    let mut entries: Vec<IconEntry> = Vec::new();

+

+    for i in 0..count {

+        let grp_offset = 6 + i * 14;

+        let icon_id =

+            u16::from_le_bytes([grp_data[grp_offset + 12], grp_data[grp_offset + 13]]) as u32;

+

+        // Find the RT_ICON with this ID

+        let icon_sub = match icon_dir.get_dir(Name::Id(icon_id)) {

+            Ok(d) => d,

+            Err(_) => continue,

+        };

+

+        let data_entry = match icon_sub.entries().next() {

+            Some(e) => match e.entry() {

+                Ok(Entry::DataEntry(d)) => d,

+                _ => continue,

+            },

+            None => continue,

+        };

+

+        let image_data = match data_entry.bytes() {

+            Ok(d) => d,

+            Err(_) => continue,

+        };

+

+        let mut header = [0u8; 8];

+        header.copy_from_slice(&grp_data[grp_offset..grp_offset + 8]);

+

+        entries.push(IconEntry {

+            header,

+            data: image_data,

+        });

+    }

+

+    if entries.is_empty() {

+        return Err("no icon entries found".into());

+    }

+

+    let entry_count = entries.len() as u16;

+    let header_size = 6 + (entry_count as usize) * 16; // ICONDIR + ICONDIRENTRYs

+

+    let mut ico = Vec::new();

+

+    // ICONDIR header

+    ico.extend_from_slice(&0u16.to_le_bytes()); // reserved

+    ico.extend_from_slice(&1u16.to_le_bytes()); // type = ICO

+    ico.extend_from_slice(&entry_count.to_le_bytes());

+

+    // Write ICONDIRENTRY records (16 bytes each)

+    let mut data_offset = header_size as u32;

+    for entry in &entries {

+        ico.extend_from_slice(&entry.header); // width, height, colors, reserved, planes, bpp (8 bytes)

+        let size = entry.data.len() as u32;

+        ico.extend_from_slice(&size.to_le_bytes()); // dwBytesInRes (4 bytes)

+        ico.extend_from_slice(&data_offset.to_le_bytes()); // dwImageOffset (4 bytes)

+        data_offset += size;

+    }

+

+    // Write image data

+    for entry in &entries {

+        ico.extend_from_slice(entry.data);

+    }

+

+    Ok(ico)

+}

diff --git a/libs/nak/src/lib.rs b/libs/nak/src/lib.rs
index 59f41c6..13bc90e 100644
--- a/libs/nak/src/lib.rs
+++ b/libs/nak/src/lib.rs
@@ -13,4 +13,5 @@ pub mod steam;
 pub mod utils;
 
 pub mod deps;
+pub mod icons;
 pub mod installers;