Add SGI Image (.rgb) decoder

Author: mstoeckl

Cargo.toml

@@ -8,12 +8,13 @@ publish = false
 include = ["src", "tests/reference.rs"]
 
 [features]
-default = ["ora", "otb", "pcx", "xbm", "xpm", "wbmp"]
+default = ["ora", "otb", "pcx", "sgi", "xbm", "xpm", "wbmp"]
 
 # Each feature below is the file extention for the file format decoder it
 # enables.
 ora = ["image/png", "dep:zip", "dep:ouroboros"]
 otb = []
+sgi = []
 pcx = ["dep:pcx"]
 wbmp = ["dep:wbmp"]
 xbm = []

README.md

@@ -11,6 +11,7 @@ Decoding support for additional image formats beyond those provided by the
 | PCX | [Wikipedia](https://en.wikipedia.org/wiki/PCX#PCX_file_format) |
 | WBMP | [Specification](https://www.wapforum.org/what/technical/SPEC-WAESpec-19990524.pdf) |
 | OTB | [Specification](https://www.wapforum.org/what/technical/SPEC-WAESpec-19990524.pdf) |
+| RGB | [Wikipedia](https://en.wikipedia.org/wiki/Silicon_Graphics_Image) |
 | XBM | [Specification](https://www.x.org/releases/X11R7.7/doc/libX11/libX11/libX11.html#Manipulating_Bitmaps) |
 | XPM | [Specification](https://www.x.org/docs/XPM/xpm.pdf) |
 

fuzz/Cargo.toml

@@ -37,3 +37,7 @@ path = "fuzzers/fuzzer_script_xpm.rs"
 [[bin]]
 name = "fuzzer_script_ora"
 path = "fuzzers/fuzzer_script_ora.rs"
+
+[[bin]]
+name = "fuzzer_script_sgi"
+path = "fuzzers/fuzzer_script_sgi.rs"

fuzz/fuzzers/fuzzer_script_sgi.rs

@@ -0,0 +1,22 @@
+#![no_main]
+#[macro_use]
+extern crate libfuzzer_sys;
+
+use image::ImageDecoder;
+use std::io::Cursor;
+
+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

@@ -26,6 +26,9 @@ pub mod otb;
 #[cfg(feature = "pcx")]
 pub mod pcx;
 
+#[cfg(feature = "sgi")]
+pub mod sgi;
+
 #[cfg(feature = "wbmp")]
 pub mod wbmp;
 
@@ -70,6 +73,50 @@ pub fn register() {
             register_format_detection_hook("pcx".into(), &[0x0a, 0x0], Some(b"\xFF\xF8"));
         }
 
+        // 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
+        #[cfg(feature = "sgi")]
+        {
+            let hook: for<'a> fn(
+                image::hooks::GenericReader<'a>,
+            )
+                -> image::ImageResult<Box<dyn image::ImageDecoder + 'a>> =
+                |r| Ok(Box::new(sgi::SgiDecoder::new(r)?));
+            image::hooks::register_decoding_hook("bw".into(), Box::new(hook));
+            image::hooks::register_decoding_hook("rgb".into(), Box::new(hook));
+            image::hooks::register_decoding_hook("rgba".into(), Box::new(hook));
+            image::hooks::register_decoding_hook("iris".into(), Box::new(hook));
+            if image::hooks::register_decoding_hook("sgi".into(), Box::new(hook)) {
+                // The main signature bytes are 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,
+                );
+            }
+        }
+
         #[cfg(feature = "wbmp")]
         image::hooks::register_decoding_hook(
             "wbmp".into(),