Add SGI Image (.rgb) decoder

Author: mstoeckl

Cargo.toml

@@ -8,10 +8,11 @@ publish = false
 include = ["src", "tests/reference.rs"]
 
 [features]
-default = ["pcx", "xbm", "xpm"]
+default = ["pcx", "xbm", "xpm", "sgi"]
 pcx = ["dep:pcx"]
 xbm = []
 xpm = ["dep:image-x11r6colors"]
+sgi = []
 
 [dependencies]
 image = { version = "0.25.5", default-features = false }

fuzz/Cargo.toml

@@ -33,3 +33,7 @@ path = "fuzzers/fuzzer_script_xbm.rs"
 [[bin]]
 name = "fuzzer_script_xpm"
 path = "fuzzers/fuzzer_script_xpm.rs"
+
+[[bin]]
+name = "fuzzer_script_sgi"
+path = "fuzzers/fuzzer_script_sgi.rs"

fuzz/fuzzers/fuzzer_script_sgi.rs

@@ -0,0 +1,21 @@
+#![no_main]
+#[macro_use] extern crate libfuzzer_sys;
+
+use std::io::Cursor;
+use image::ImageDecoder;
+
+fuzz_target!(|data: &[u8]| {
+    let reader = Cursor::new(data);
+    let Ok(mut decoder) = image_extras::sgi::SgiDecoder::new(reader) else {
+        return;
+    };
+    let mut limits = image::Limits::default();
+    limits.max_alloc = Some(1024 * 1024); // 1 MiB
+    if limits.reserve(decoder.total_bytes()).is_err() {
+        return;
+    }
+    if decoder.set_limits(limits).is_err() {
+        return;
+    }
+    let _ = std::hint::black_box(image::DynamicImage::from_decoder(decoder));
+});

src/lib.rs

@@ -24,6 +24,9 @@ pub mod xbm;
 #[cfg(feature = "xpm")]
 pub mod xpm;
 
+#[cfg(feature = "sgi")]
+pub mod sgi;
+
 /// Register all enabled extra formats with the image crate.
 pub fn register() {
     image::hooks::register_decoding_hook(
@@ -47,4 +50,38 @@ pub fn register() {
         Box::new(|r| Ok(Box::new(xpm::XpmDecoder::new(r)?))),
     );
     image::hooks::register_format_detection_hook("xpm".into(), b"/* XPM */", None);
+
+    // SGI RGB images generally show up with a .rgb ending (whether or not they
+    // have 3 channels), and sometimes .bw (when grayscale) and .rgba. The
+    // extensions .sgi and .iris, while unambiguous, do not seem to have been
+    // used much. The extension .rgb is also used for a variety of other files,
+    // including bare image data, so to be sure it would be best to check both
+    // extension and leading bytes
+    image::hooks::register_decoding_hook(
+        "bw".into(),
+        Box::new(|r| Ok(Box::new(sgi::SgiDecoder::new(r)?))),
+    );
+    image::hooks::register_decoding_hook(
+        "rgb".into(),
+        Box::new(|r| Ok(Box::new(sgi::SgiDecoder::new(r)?))),
+    );
+    image::hooks::register_decoding_hook(
+        "rgba".into(),
+        Box::new(|r| Ok(Box::new(sgi::SgiDecoder::new(r)?))),
+    );
+    image::hooks::register_decoding_hook(
+        "sgi".into(),
+        Box::new(|r| Ok(Box::new(sgi::SgiDecoder::new(r)?))),
+    );
+    image::hooks::register_decoding_hook(
+        "iris".into(),
+        Box::new(|r| Ok(Box::new(sgi::SgiDecoder::new(r)?))),
+    );
+    // The main signature bytes technically just 01 da, but this is short and
+    // the following storage and bpc fields are constrained well enough to
+    // efficiently match them as well
+    image::hooks::register_format_detection_hook("sgi".into(), b"\x01\xda\x00\x01", None);
+    image::hooks::register_format_detection_hook("sgi".into(), b"\x01\xda\x01\x01", None);
+    image::hooks::register_format_detection_hook("sgi".into(), b"\x01\xda\x00\x02", None);
+    image::hooks::register_format_detection_hook("sgi".into(), b"\x01\xda\x01\x02", None);
 }