Add partial support for SVG

Author: qarmin

src/map.rs

@@ -191,6 +191,12 @@ matcher_map!(
         "avif",
         matchers::image::is_avif
     ),
+    (
+        MatcherType::Image,
+        "image/svg+xml",
+        "svg",
+        matchers::image::is_svg
+    ),
     // Video
     (
         MatcherType::Video,

src/matchers/image.rs

@@ -160,3 +160,9 @@ fn get_ftyp(buf: &[u8]) -> Option<(&[u8], &[u8], impl Iterator<Item = &[u8]>)> {
 
     Some((major, minor, compatible))
 }
+
+/// Returns whether a buffer is SVG.
+pub fn is_svg(buf: &[u8]) -> bool {
+    // ref: https://stackoverflow.com/a/66975778
+    buf.len() > 4 && buf[0] == b'<' && buf[1] == b's' && buf[2] == b'v' && buf[3] == b'g'
+}

testdata/sample.svg

@@ -25,3 +25,5 @@ test_format!(Image, "image/vnd.microsoft.icon", "ico", ico, "sample.ico");
 test_format!(Image, "image/heif", "heif", heif, "sample.heic");
 
 test_format!(Image, "image/avif", "avif", avif, "sample.avif");
+
+test_format!(Image, "image/svg+xml", "svg", svg, "sample.svg");