Improve fuzzing (#129)

Add targets for fuzzing properties, implementation correctness, and
algorithm properties. Add binaries for debug and analysis. Also add
scripts for convenience.

Author: ia0

.github/workflows/ci.yml

@@ -61,7 +61,12 @@ jobs:
     - name: cd nostd && cargo +nightly clippy -- --deny=warnings
       run: cargo +nightly clippy -- --deny=warnings
       working-directory: nostd
+    - name: cd lib/fuzz && cargo +nightly clippy --lib --examples -- --deny=warnings
+      run: cargo +nightly clippy --lib --examples -- --deny=warnings
+      working-directory: lib/fuzz
     - name: cd lib/fuzz && cargo +nightly clippy -- --deny=warnings
+      env:
+        RUSTFLAGS: --cfg=fuzzing
       run: cargo +nightly clippy -- --deny=warnings
       working-directory: lib/fuzz
     - name: cd lib && cargo +nightly build
@@ -103,7 +108,12 @@ jobs:
     - name: cd nostd && cargo +nightly build --release
       run: cargo +nightly build --release
       working-directory: nostd
+    - name: cd lib/fuzz && cargo +nightly build --lib --examples
+      run: cargo +nightly build --lib --examples
+      working-directory: lib/fuzz
     - name: cd lib/fuzz && cargo +nightly build
+      env:
+        RUSTFLAGS: --cfg=fuzzing
       run: cargo +nightly build
       working-directory: lib/fuzz
     - name: cd cmp && cargo +nightly build
@@ -128,8 +138,8 @@ jobs:
     - name: cd nostd && cargo +nightly run --release --features=alloc
       run: cargo +nightly run --release --features=alloc
       working-directory: nostd
-    - name: cd lib/fuzz && cargo +nightly test
-      run: cargo +nightly test
+    - name: cd lib/fuzz && cargo +nightly test --lib
+      run: cargo +nightly test --lib
       working-directory: lib/fuzz
     - name: cd cmp && cargo +nightly test
       run: cargo +nightly test

lib/fuzz/Cargo.toml

@@ -4,7 +4,6 @@ version = "0.0.0"
 authors = ["Automatically generated"]
 publish = false
 edition = "2021"
-rust-version = "1.81"
 
 [package.metadata]
 cargo-fuzz = true
@@ -13,20 +12,42 @@ cargo-fuzz = true
 data-encoding = { path = ".." }
 libfuzzer-sys = "0.4.3"
 
+# Fuzz targets organization based on prefix:
+# - fuzz_FOO: FOO holds for the fuzzing tools (property testing)
+# - impl_FOO: FOO is correctly implemented (differential testing)
+# - spec_FOO: FOO holds for the specification (property testing)
+
+[[bin]]
+name = "fuzz_any_spec"
+path = "fuzz_targets/fuzz_any_spec.rs"
+
+[[bin]]
+name = "impl_encode"
+path = "fuzz_targets/impl_encode.rs"
+
+[[bin]]
+name = "impl_decode"
+path = "fuzz_targets/impl_decode.rs"
+
+[[bin]]
+name = "impl_new_encoder"
+path = "fuzz_targets/impl_new_encoder.rs"
+
 [[bin]]
-name = "round_trip"
-path = "fuzz_targets/round_trip.rs"
-test = false
-doc = false
+name = "impl_encode_write_buffer"
+path = "fuzz_targets/impl_encode_write_buffer.rs"
 
 [[bin]]
-name = "encoder"
-path = "fuzz_targets/encoder.rs"
-test = false
-doc = false
+name = "spec_spec_base"
+path = "fuzz_targets/spec_spec_base.rs"
 
 [[bin]]
-name = "encode_write"
-path = "fuzz_targets/encode_write.rs"
-test = false
-doc = false
+name = "spec_encode_decode"
+path = "fuzz_targets/spec_encode_decode.rs"
+
+[[bin]]
+name = "spec_decode_encode"
+path = "fuzz_targets/spec_decode_encode.rs"
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(fuzzing)'] }

lib/fuzz/analyze.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+cargo run --manifest-path=fuzz/Cargo.toml --release --example=analyze -- "$@"

lib/fuzz/compact.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+for target in $(cargo fuzz list); do
+  cargo fuzz cmin $target
+done

lib/fuzz/debug.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+cargo run --manifest-path=fuzz/Cargo.toml --example=debug -- "$1"