From 256a668f47df9f1dc0f0f05b8eef4021ce7c81cb Mon Sep 17 00:00:00 2001
From: Martin Geisler <martin@geisler.net>
Date: Fri, 18 Dec 2020 08:00:02 +0100
Subject: [PATCH] Introduce fuzz tests for wrap_optimal_fit and wrap_first_fit
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These fuzz tests immediately found the problem reported in #247 and
gave a short way of reproducing it:

    wrap("x y", 515566821223)

will currently panic due to an overflow error. The wrap_first_fit
function seems to not crash.

Run the fuzz tests with:

    $ cargo fuzz run fill_optimal_fit -- -only_ascii=1

You’ll need to `cargo install cargo-fuzz` first.
---
 Cargo.toml                            |  2 +-
 fuzz/.gitignore                       |  3 +++
 fuzz/Cargo.toml                       | 30 +++++++++++++++++++++++++++
 fuzz/fuzz_targets/fill_first_fit.rs   |  9 ++++++++
 fuzz/fuzz_targets/fill_optimal_fit.rs |  9 ++++++++
 5 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 fuzz/.gitignore
 create mode 100644 fuzz/Cargo.toml
 create mode 100644 fuzz/fuzz_targets/fill_first_fit.rs
 create mode 100644 fuzz/fuzz_targets/fill_optimal_fit.rs

diff --git a/Cargo.toml b/Cargo.toml
index 71163cab..9117c774 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,7 @@ keywords = ["text", "formatting", "wrap", "typesetting", "hyphenation"]
 categories = ["text-processing", "command-line-interface"]
 license = "MIT"
 edition = "2018"
-exclude = [".github/", ".gitignore", "benches/", "examples/"]
+exclude = [".github/", ".gitignore", "benches/", "examples/", "fuzz/"]
 
 [package.metadata.docs.rs]
 all-features = true
diff --git a/fuzz/.gitignore b/fuzz/.gitignore
new file mode 100644
index 00000000..188f1960
--- /dev/null
+++ b/fuzz/.gitignore
@@ -0,0 +1,3 @@
+artifacts/
+corpus/
+target/
diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
new file mode 100644
index 00000000..193b1f4d
--- /dev/null
+++ b/fuzz/Cargo.toml
@@ -0,0 +1,30 @@
+
+[package]
+name = "textwrap-fuzz"
+version = "0.0.0"
+authors = ["Automatically generated"]
+publish = false
+edition = "2018"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.3"
+textwrap = { path = ".." }
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[[bin]]
+name = "fill_optimal_fit"
+path = "fuzz_targets/fill_optimal_fit.rs"
+test = false
+doc = false
+
+[[bin]]
+name = "fill_first_fit"
+path = "fuzz_targets/fill_first_fit.rs"
+test = false
+doc = false
diff --git a/fuzz/fuzz_targets/fill_first_fit.rs b/fuzz/fuzz_targets/fill_first_fit.rs
new file mode 100644
index 00000000..3e1f0a7f
--- /dev/null
+++ b/fuzz/fuzz_targets/fill_first_fit.rs
@@ -0,0 +1,9 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+use textwrap::core::WrapAlgorithm::FirstFit;
+use textwrap::Options;
+
+fuzz_target!(|input: (String, usize)| {
+    let options = Options::new(input.1).wrap_algorithm(FirstFit);
+    let _ = textwrap::fill(&input.0, &options);
+});
diff --git a/fuzz/fuzz_targets/fill_optimal_fit.rs b/fuzz/fuzz_targets/fill_optimal_fit.rs
new file mode 100644
index 00000000..13740cb7
--- /dev/null
+++ b/fuzz/fuzz_targets/fill_optimal_fit.rs
@@ -0,0 +1,9 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+use textwrap::core::WrapAlgorithm::OptimalFit;
+use textwrap::Options;
+
+fuzz_target!(|input: (String, usize)| {
+    let options = Options::new(input.1).wrap_algorithm(OptimalFit);
+    let _ = textwrap::fill(&input.0, &options);
+});