feat: Make Cosmic Files show .exe icons like Dolphin

Cargo.toml

@@ -2,6 +2,7 @@
 name = "cosmic-files"
 version = "1.7.0"
 authors = ["Jeremy Soller <jeremy@system76.com>"]
+default-run = "cosmic-files"
 edition = "2024"
 license = "GPL-3.0-only"
 rust-version = "1.93"
@@ -67,6 +68,7 @@ thiserror = "2.0.18"
 atomic_float = "1.1.0"
 num_enum = "0.7.6"
 bstr = "1.12.1"
+pelite = "0.10.0"
 
 # Completion-based IO runtime to enable io_uring / IOCP file IO support.
 [dependencies.compio]

justfile

@@ -12,6 +12,10 @@ cargo-target-dir := env('CARGO_TARGET_DIR', 'target')
 bin-src := cargo-target-dir / 'release' / name
 bin-dst := base-dir / 'bin' / name
 
+thumbnailer-bin-name := name + '-thumbnailer'
+thumbnailer-bin-src := cargo-target-dir / 'release' / thumbnailer-bin-name
+thumbnailer-bin-dst := base-dir / 'bin' / thumbnailer-bin-name
+
 applet-name := name + '-applet'
 applet-src := cargo-target-dir / 'release' / applet-name
 applet-dst := base-dir / 'bin' / applet-name
@@ -24,6 +28,10 @@ metainfo := APPID + '.metainfo.xml'
 metainfo-src := 'target/xdgen' / metainfo
 metainfo-dst := clean(rootdir / prefix) / 'share' / 'metainfo' / metainfo
 
+thumbnailer := APPID + '.thumbnailer'
+thumbnailer-src := 'res' / thumbnailer
+thumbnailer-dst := clean(rootdir / prefix) / 'share' / 'thumbnailers' / thumbnailer
+
 icons-src := 'res' / 'icons' / 'hicolor'
 icons-dst := clean(rootdir / prefix) / 'share' / 'icons' / 'hicolor'
 
@@ -92,9 +100,11 @@ heaptrack *args:
 # Installs files
 install:
     install -Dm0755 {{bin-src}} {{bin-dst}}
+    install -Dm0755 {{thumbnailer-bin-src}} {{thumbnailer-bin-dst}}
     install -Dm0755 {{applet-src}} {{applet-dst}}
     install -Dm0644 {{desktop-src}} {{desktop-dst}}
     install -Dm0644 {{metainfo-src}} {{metainfo-dst}}
+    install -Dm0644 {{thumbnailer-src}} {{thumbnailer-dst}}
     for size in `ls {{icons-src}}`; do \
         install -Dm0644 "{{icons-src}}/$size/apps/{{APPID}}.svg" "{{icons-dst}}/$size/apps/{{APPID}}.svg"; \
     done
@@ -105,7 +115,7 @@ install-applet:
 
 # Uninstalls installed files
 uninstall:
-    rm -f {{bin-dst}} {{applet-dst}}
+    rm -f {{bin-dst}} {{thumbnailer-bin-dst}} {{applet-dst}} {{thumbnailer-dst}}
 
 # Vendor dependencies locally
 vendor:

res/com.system76.CosmicFiles.thumbnailer

@@ -0,0 +1,4 @@
+[Thumbnailer Entry]
+TryExec=cosmic-files-thumbnailer
+Exec=cosmic-files-thumbnailer %o --size %s %i
+MimeType=application/vnd.microsoft.portable-executable;application/x-msdownload;

src/bin/cosmic-files-thumbnailer.rs

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-3.0-only
+
+#[path = "../exe_thumbnailer.rs"]
+mod exe_thumbnailer;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    exe_thumbnailer::thumbnail_from_args(std::env::args_os().skip(1))
+}

src/exe_thumbnailer.rs

@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-3.0-only
+
+use image::{DynamicImage, ImageFormat, RgbaImage};
+use std::error::Error;
+use std::ffi::{OsStr, OsString};
+use std::io;
+use std::path::Path;
+
+#[allow(dead_code)]
+pub fn thumbnail_from_args(mut args: impl Iterator<Item = OsString>) -> Result<(), Box<dyn Error>> {
+    let usage = || {
+        io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "usage: cosmic-files-thumbnailer OUTPUT --size SIZE INPUT",
+        )
+    };
+    let output = args.next().ok_or_else(usage)?;
+    if args.next().as_deref() != Some(OsStr::new("--size")) {
+        return Err(usage().into());
+    }
+    let size = args
+        .next()
+        .and_then(|arg| arg.into_string().ok())
+        .and_then(|arg| arg.parse::<u32>().ok())
+        .filter(|size| *size > 0)
+        .ok_or_else(usage)?;
+    let input = args.next().ok_or_else(usage)?;
+    if args.next().is_some() {
+        return Err(usage().into());
+    }
+
+    thumbnail(Path::new(&input), Path::new(&output), size)
+}
+
+#[allow(dead_code)]
+pub fn thumbnail(input: &Path, output: &Path, size: u32) -> Result<(), Box<dyn Error>> {
+    let icon = thumbnail_image(input, size)?;
+    DynamicImage::ImageRgba8(icon).save_with_format(output, ImageFormat::Png)?;
+
+    Ok(())
+}
+
+pub fn thumbnail_image(input: &Path, size: u32) -> Result<RgbaImage, Box<dyn Error>> {
+    if size == 0 {
+        return Err(io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "thumbnail size must be positive",
+        )
+        .into());
+    }
+
+    // Map the PE so only the headers and resource pages touched by pelite are read.
+    let data = pelite::FileMap::open(input)?;
+    let bytes = data.as_ref();
+    if bytes.len() < 64 || !bytes.starts_with(b"MZ") {
+        return Err(io::Error::new(io::ErrorKind::InvalidData, "input is not a PE file").into());
+    }
+
+    let file = pelite::PeFile::from_bytes(bytes).map_err(invalid_data)?;
+    let resources = file.resources().map_err(invalid_data)?;
+    let (_name, group) = resources
+        .icons()
+        .next()
+        .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidData, "PE file has no icon group"))?
+        .map_err(invalid_data)?;
+
+    let mut ico = Vec::new();
+    group.write(&mut ico).map_err(invalid_data)?;
+
+    Ok(
+        DynamicImage::ImageRgba8(largest_icon(&ico).map_err(invalid_data)?)
+            .thumbnail(size, size)
+            .into_rgba8(),
+    )
+}
+
+fn invalid_data(error: impl std::fmt::Display) -> io::Error {
+    io::Error::new(io::ErrorKind::InvalidData, error.to_string())
+}
+
+fn largest_icon(ico: &[u8]) -> Result<RgbaImage, String> {
+    if ico.len() < 6 {
+        return Err("ICO header is truncated".to_string());
+    }
+    let count = usize::from(u16::from_le_bytes([ico[4], ico[5]]));
+    let mut best: Option<(u64, RgbaImage)> = None;
+    let mut errors = Vec::new();
+
+    for i in 0..count.min(32) {
+        let entry = 6 + i * 16;
+        if ico.len() < entry + 16 {
+            break;
+        }
+        let size = u32::from_le_bytes([
+            ico[entry + 8],
+            ico[entry + 9],
+            ico[entry + 10],
+            ico[entry + 11],
+        ]) as usize;
+        let offset = u32::from_le_bytes([
+            ico[entry + 12],
+            ico[entry + 13],
+            ico[entry + 14],
+            ico[entry + 15],
+        ]) as usize;
+        let Some(end) = offset.checked_add(size) else {
+            continue;
+        };
+        let Some(data) = ico.get(offset..end) else {
+            continue;
+        };
+
+        match decode_icon(&ico[entry..entry + 16], data) {
+            Ok(image) => {
+                let pixels = u64::from(image.width()) * u64::from(image.height());
+                if best
+                    .as_ref()
+                    .is_none_or(|(best_pixels, _)| pixels > *best_pixels)
+                {
+                    best = Some((pixels, image));
+                }
+            }
+            Err(err) => errors.push(format!("frame {i}: {err}")),
+        }
+    }
+
+    best.map(|(_, image)| image).ok_or_else(|| {
+        if errors.is_empty() {
+            "PE icon contains no complete frames".to_string()
+        } else {
+            format!("PE icon could not be decoded ({})", errors.join("; "))
+        }
+    })
+}
+
+fn decode_icon(entry: &[u8], data: &[u8]) -> Result<RgbaImage, String> {
+    if data.starts_with(b"\x89PNG\r\n\x1a\n") {
+        return image::ImageReader::with_format(io::Cursor::new(data), ImageFormat::Png)
+            .decode()
+            .map(DynamicImage::into_rgba8)
+            .map_err(|err| err.to_string());
+    }
+
+    let capacity = 22usize
+        .checked_add(data.len())
+        .ok_or_else(|| "frame is too large".to_string())?;
+    let data_len = u32::try_from(data.len()).map_err(|_| "frame is too large".to_string())?;
+    let mut ico = Vec::with_capacity(capacity);
+    ico.extend_from_slice(&[0, 0, 1, 0, 1, 0]);
+    ico.extend_from_slice(entry);
+    ico[14..18].copy_from_slice(&data_len.to_le_bytes());
+    ico[18..22].copy_from_slice(&22u32.to_le_bytes());
+    ico.extend_from_slice(data);
+
+    image::ImageReader::with_format(io::Cursor::new(ico), ImageFormat::Ico)
+        .decode()
+        .map(DynamicImage::into_rgba8)
+        .map_err(|err| err.to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{largest_icon, thumbnail_from_args};
+    use image::{DynamicImage, ImageFormat, Rgb, RgbImage, Rgba, RgbaImage};
+    use std::ffi::OsString;
+    use std::io::Cursor;
+
+    #[test]
+    fn malformed_thumbnail_request_returns_an_error() {
+        let args = [OsString::from("output.png")];
+        assert!(thumbnail_from_args(args.into_iter()).is_err());
+    }
+
+    #[test]
+    fn largest_icon_skips_invalid_entries() {
+        let image = RgbaImage::from_pixel(2, 2, Rgba([1, 2, 3, 255]));
+        let mut png = Cursor::new(Vec::new());
+        DynamicImage::ImageRgba8(image)
+            .write_to(&mut png, ImageFormat::Png)
+            .unwrap();
+        let png = png.into_inner();
+
+        let mut ico = vec![0, 0, 1, 0, 2, 0];
+        let mut invalid_entry = [0; 16];
+        invalid_entry[8..12].copy_from_slice(&4u32.to_le_bytes());
+        invalid_entry[12..16].copy_from_slice(&u32::MAX.to_le_bytes());
+        ico.extend_from_slice(&invalid_entry);
+
+        let mut valid_entry = [0; 16];
+        valid_entry[..8].copy_from_slice(&[2, 2, 0, 0, 1, 0, 32, 0]);
+        valid_entry[8..12].copy_from_slice(&u32::try_from(png.len()).unwrap().to_le_bytes());
+        valid_entry[12..16].copy_from_slice(&38u32.to_le_bytes());
+        ico.extend_from_slice(&valid_entry);
+        ico.extend_from_slice(&png);
+
+        let decoded = largest_icon(&ico).expect("valid icon after malformed entry");
+        assert_eq!(decoded.dimensions(), (2, 2));
+        assert_eq!(decoded.get_pixel(0, 0), &Rgba([1, 2, 3, 255]));
+    }
+
+    #[test]
+    fn dib_and_mask_is_applied() {
+        let mut dib = vec![0; 40];
+        dib[0..4].copy_from_slice(&40u32.to_le_bytes());
+        dib[4..8].copy_from_slice(&2i32.to_le_bytes());
+        dib[8..12].copy_from_slice(&4i32.to_le_bytes());
+        dib[12..14].copy_from_slice(&1u16.to_le_bytes());
+        dib[14..16].copy_from_slice(&24u16.to_le_bytes());
+
+        // Two bottom-up BGR rows, padded to four-byte boundaries.
+        dib.extend_from_slice(&[0, 0, 255, 0, 0, 255, 0, 0]);
+        dib.extend_from_slice(&[0, 0, 255, 0, 0, 255, 0, 0]);
+        // The first mask row is the bottom image row; its first pixel is transparent.
+        dib.extend_from_slice(&[0b1000_0000, 0, 0, 0]);
+        dib.extend_from_slice(&[0, 0, 0, 0]);
+
+        let mut ico = vec![0, 0, 1, 0, 1, 0];
+        let mut entry = [0; 16];
+        entry[..8].copy_from_slice(&[2, 2, 0, 0, 1, 0, 24, 0]);
+        entry[8..12].copy_from_slice(&u32::try_from(dib.len()).unwrap().to_le_bytes());
+        entry[12..16].copy_from_slice(&22u32.to_le_bytes());
+        ico.extend_from_slice(&entry);
+        ico.extend_from_slice(&dib);
+
+        let decoded = largest_icon(&ico).expect("valid DIB icon");
+        assert_eq!(decoded.get_pixel(0, 0), &Rgba([255, 0, 0, 255]));
+        assert_eq!(decoded.get_pixel(0, 1), &Rgba([255, 0, 0, 0]));
+    }
+
+    #[test]
+    fn rgb_png_icon_is_decoded() {
+        let image = RgbImage::from_pixel(2, 2, Rgb([1, 2, 3]));
+        let mut png = Cursor::new(Vec::new());
+        DynamicImage::ImageRgb8(image)
+            .write_to(&mut png, ImageFormat::Png)
+            .unwrap();
+        let png = png.into_inner();
+
+        let mut ico = vec![0, 0, 1, 0, 1, 0];
+        let mut entry = [0; 16];
+        entry[..8].copy_from_slice(&[2, 2, 0, 0, 1, 0, 24, 0]);
+        entry[8..12].copy_from_slice(&u32::try_from(png.len()).unwrap().to_le_bytes());
+        entry[12..16].copy_from_slice(&22u32.to_le_bytes());
+        ico.extend_from_slice(&entry);
+        ico.extend_from_slice(&png);
+
+        let decoded = largest_icon(&ico).expect("valid RGB PNG icon");
+        assert_eq!(decoded.get_pixel(0, 0), &Rgba([1, 2, 3, 255]));
+    }
+}