Add fuzz target for rustfmt crate

Cf. rust-fuzz#37

Cargo.toml

@@ -2,11 +2,12 @@
 members = [
     "crypto-hashes",
     "cssparser",
-    "httparse",
     "flac",
+    "httparse",
     "mp4parse",
     "pulldown-cmark",
     "quick-xml",
+    "regex",
     "serde_json",
     "tar",
     "xml-rs",

regex/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "regex-targets"
+version = "0.0.0"
+publish = false
+
+[dependencies]
+regex = { git = "https://github.com/rust-lang-nursery/regex" }
+libfuzzer-sys = { git = "https://github.com/rust-fuzz/libfuzzer-sys.git" }
+
+[[bin]]
+name = "is_match"
+path = "is_match.rs"

regex/is_match.rs

@@ -0,0 +1,21 @@
+#![no_main]
+
+#[macro_use] extern crate libfuzzer_sys;
+extern crate regex;
+
+fuzz_target!(|data: &[u8]| {
+    if let Ok(data) = std::str::from_utf8(data) {
+        // split data into regular expression and actual input to search through
+        use std::cmp::max;
+        let len = data.chars().count();
+        let split_off_point = max(len / 5, 1) as usize;
+        let char_index = data.char_indices().nth(split_off_point);
+
+        if let Some((char_index, _)) = char_index {
+            let (pattern, input) = data.split_at(char_index);
+            if let Ok(re) = regex::Regex::new(pattern) {
+                re.is_match(input);
+            }
+        }
+    }
+});