fuzz: add harness for filters and escape

Cargo.toml

@@ -10,6 +10,9 @@ members = [
     "askama_warp",
     "testing",
 ]
+
+exclude = ["fuzz"]
+
 resolver = "2"
 
 default-members = [

fuzz/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "askama-fuzz"
+version = "0.0.0"
+publish = false
+edition = "2021"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+arbitrary = "1.3.2"
+askama = { path = "../askama" }
+askama_parser = { path = "../askama_parser" }
+askama_escape = { path = "../askama_escape" }
+
+[profile.release]
+debug = 1
+
+[[bin]]
+name = "askama_parser-fuzz_parser"
+path = "fuzz_targets/fuzz_parser.rs"
+test = false
+doc = false
+
+[[bin]]
+name = "fuzz_filters"
+path = "fuzz_targets/fuzz_filters.rs"
+test = false
+doc = false

fuzz/fuzz_targets/fuzz_filters.rs

@@ -0,0 +1,74 @@
+#![no_main]
+use arbitrary::{Arbitrary, Unstructured};
+use askama::filters::*;
+use askama_escape::Html;
+use libfuzzer_sys::fuzz_target;
+use std::str::{self};
+
+macro_rules! fuzz {
+    ($name: ident, $func: ident) => {
+        fn $name(data: &[u8]) {
+            if let Ok(data) = str::from_utf8(data) {
+                if let Ok(d) = $func(data) {
+                    let _ = d.to_string();
+                }
+            }
+        }
+    };
+    ($name: ident, $func: ident, $arg_type: ty) => {
+        fn $name(data: &[u8]) {
+            if let Some(adata) = get_arbitrary_data::<$arg_type>(data) {
+                if let Ok(sdata) = str::from_utf8(data) {
+                    if let Ok(d) = $func(sdata, adata) {
+                        let _ = d.to_string();
+                    }
+                }
+            }
+        }
+    };
+}
+
+fn get_arbitrary_data<'a, T>(data: &'a [u8]) -> Option<T>
+where
+    T: Arbitrary<'a>,
+{
+    T::arbitrary(&mut Unstructured::new(data)).ok()
+}
+
+fuzz!(fuzz_urlencode, urlencode);
+fuzz!(fuzz_urlencode_strict, urlencode_strict);
+fuzz!(fuzz_linebreaks, linebreaks);
+fuzz!(fuzz_paragraphbreaks, paragraphbreaks);
+fuzz!(fuzz_trim, trim);
+fuzz!(fuzz_title, title);
+fuzz!(fuzz_capitalize, capitalize);
+fuzz!(fuzz_truncate, truncate, usize);
+fuzz!(fuzz_indent, indent, usize);
+fuzz!(fuzz_center, center, usize);
+
+fn fuzz_escape(data: &[u8]) {
+    if let Ok(data) = str::from_utf8(data) {
+        let _ = askama_escape::escape(data, Html);
+    }
+}
+
+fuzz_target!(|data: &[u8]| {
+    if data.is_empty() {
+        return;
+    }
+    let idx = data[0] % 11;
+    let data = &data[1..];
+    match idx {
+        0 => fuzz_urlencode(data),
+        1 => fuzz_urlencode_strict(data),
+        2 => fuzz_linebreaks(data),
+        3 => fuzz_paragraphbreaks(data),
+        4 => fuzz_trim(data),
+        5 => fuzz_title(data),
+        6 => fuzz_capitalize(data),
+        7 => fuzz_truncate(data),
+        8 => fuzz_indent(data),
+        9 => fuzz_escape(data),
+        _ => fuzz_center(data),
+    }
+});

askama_parser/fuzz/fuzz_targets/fuzz_parser.rs → fuzz/fuzz_targets/fuzz_parser.rs

@@ -1,11 +1,10 @@
 #![no_main]
 use askama_parser::*;
 use libfuzzer_sys::fuzz_target;
-use std::str;
 
 fuzz_target!(|data: &[u8]| {
     // fuzzed code goes here
-    if let Ok(data) = str::from_utf8(data) {
-        if let Ok(_) = Ast::from_str(data, None, &Syntax::default()) {}
+    if let Ok(data) = std::str::from_utf8(data) {
+        let _ = Ast::from_str(data, None, &Syntax::default()).is_ok();
     }
 });