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| 1 | +// Copyright (c) The Bitcoin Core developers |
| 2 | +// Distributed under the MIT software license, see the accompanying |
| 3 | +// file COPYING or https://opensource.org/license/mit/. |
| 4 | + |
| 5 | +use std::env; |
| 6 | +use std::fs::{read_dir, File}; |
| 7 | +use std::path::Path; |
| 8 | +use std::process::{exit, Command, Stdio}; |
| 9 | +use std::str; |
| 10 | + |
| 11 | +const LLVM_PROFDATA: &str = "llvm-profdata"; |
| 12 | +const LLVM_COV: &str = "llvm-cov"; |
| 13 | +const DIFF: &str = "diff"; |
| 14 | + |
| 15 | +fn exit_help(err: &str) -> ! { |
| 16 | + eprintln!("Error: {}", err); |
| 17 | + eprintln!(); |
| 18 | + eprintln!("Usage: program ./build_dir ./qa-assets-corpora-dir fuzz_target"); |
| 19 | + eprintln!(); |
| 20 | + eprintln!("Refer to the devtools/README.md for more details."); |
| 21 | + exit(1) |
| 22 | +} |
| 23 | + |
| 24 | +fn sanity_check(corpora_dir: &Path, fuzz_exe: &Path) { |
| 25 | + for tool in [LLVM_PROFDATA, LLVM_COV, DIFF] { |
| 26 | + let output = Command::new(tool).arg("--version").output(); |
| 27 | + match output { |
| 28 | + Ok(output) if output.status.success() => {} |
| 29 | + _ => { |
| 30 | + exit_help(&format!("The tool {} is not installed", tool)); |
| 31 | + } |
| 32 | + } |
| 33 | + } |
| 34 | + if !corpora_dir.is_dir() { |
| 35 | + exit_help(&format!( |
| 36 | + "Fuzz corpora path ({}) must be a directory", |
| 37 | + corpora_dir.display() |
| 38 | + )); |
| 39 | + } |
| 40 | + if !fuzz_exe.exists() { |
| 41 | + exit_help(&format!( |
| 42 | + "Fuzz executable ({}) not found", |
| 43 | + fuzz_exe.display() |
| 44 | + )); |
| 45 | + } |
| 46 | +} |
| 47 | + |
| 48 | +fn main() { |
| 49 | + // Parse args |
| 50 | + let args = env::args().collect::<Vec<_>>(); |
| 51 | + let build_dir = args |
| 52 | + .get(1) |
| 53 | + .unwrap_or_else(|| exit_help("Must set build dir")); |
| 54 | + if build_dir == "--help" { |
| 55 | + exit_help("--help requested") |
| 56 | + } |
| 57 | + let corpora_dir = args |
| 58 | + .get(2) |
| 59 | + .unwrap_or_else(|| exit_help("Must set fuzz corpora dir")); |
| 60 | + let fuzz_target = args |
| 61 | + .get(3) |
| 62 | + // Require fuzz target for now. In the future it could be optional and the tool could |
| 63 | + // iterate over all compiled fuzz targets |
| 64 | + .unwrap_or_else(|| exit_help("Must set fuzz target")); |
| 65 | + if args.get(4).is_some() { |
| 66 | + exit_help("Too many args") |
| 67 | + } |
| 68 | + |
| 69 | + let build_dir = Path::new(build_dir); |
| 70 | + let corpora_dir = Path::new(corpora_dir); |
| 71 | + let fuzz_exe = build_dir.join("src/test/fuzz/fuzz"); |
| 72 | + |
| 73 | + sanity_check(corpora_dir, &fuzz_exe); |
| 74 | + |
| 75 | + deterministic_coverage(build_dir, corpora_dir, &fuzz_exe, fuzz_target); |
| 76 | +} |
| 77 | + |
| 78 | +fn using_libfuzzer(fuzz_exe: &Path) -> bool { |
| 79 | + println!("Check if using libFuzzer ..."); |
| 80 | + let stderr = Command::new(fuzz_exe) |
| 81 | + .arg("-help=1") // Will be interpreted as option (libfuzzer) or as input file |
| 82 | + .env("FUZZ", "addition_overflow") // Any valid target |
| 83 | + .output() |
| 84 | + .expect("fuzz failed") |
| 85 | + .stderr; |
| 86 | + let help_output = str::from_utf8(&stderr).expect("The -help=1 output must be valid text"); |
| 87 | + help_output.contains("libFuzzer") |
| 88 | +} |
| 89 | + |
| 90 | +fn deterministic_coverage( |
| 91 | + build_dir: &Path, |
| 92 | + corpora_dir: &Path, |
| 93 | + fuzz_exe: &Path, |
| 94 | + fuzz_target: &str, |
| 95 | +) { |
| 96 | + let using_libfuzzer = using_libfuzzer(fuzz_exe); |
| 97 | + let profraw_file = build_dir.join("fuzz_det_cov.profraw"); |
| 98 | + let profdata_file = build_dir.join("fuzz_det_cov.profdata"); |
| 99 | + let corpus_dir = corpora_dir.join(fuzz_target); |
| 100 | + let mut entries = read_dir(&corpus_dir) |
| 101 | + .unwrap_or_else(|err| { |
| 102 | + exit_help(&format!( |
| 103 | + "The fuzz target's input directory must exist! ({}; {})", |
| 104 | + corpus_dir.display(), |
| 105 | + err |
| 106 | + )) |
| 107 | + }) |
| 108 | + .map(|entry| entry.expect("IO error")) |
| 109 | + .collect::<Vec<_>>(); |
| 110 | + entries.sort_by_key(|entry| entry.file_name()); |
| 111 | + let run_single = |run_id: u8, entry: &Path| { |
| 112 | + let cov_txt_path = build_dir.join(format!("fuzz_det_cov.show.{run_id}.txt")); |
| 113 | + assert!({ |
| 114 | + { |
| 115 | + let mut cmd = Command::new(fuzz_exe); |
| 116 | + if using_libfuzzer { |
| 117 | + cmd.arg("-runs=1"); |
| 118 | + } |
| 119 | + cmd |
| 120 | + } |
| 121 | + .env("LLVM_PROFILE_FILE", &profraw_file) |
| 122 | + .env("FUZZ", fuzz_target) |
| 123 | + .arg(entry) |
| 124 | + .status() |
| 125 | + .expect("fuzz failed") |
| 126 | + .success() |
| 127 | + }); |
| 128 | + assert!(Command::new(LLVM_PROFDATA) |
| 129 | + .arg("merge") |
| 130 | + .arg("--sparse") |
| 131 | + .arg(&profraw_file) |
| 132 | + .arg("-o") |
| 133 | + .arg(&profdata_file) |
| 134 | + .status() |
| 135 | + .expect("merge failed") |
| 136 | + .success()); |
| 137 | + let cov_file = File::create(&cov_txt_path).expect("Failed to create coverage txt file"); |
| 138 | + let passed = Command::new(LLVM_COV) |
| 139 | + .args([ |
| 140 | + "show", |
| 141 | + "--show-line-counts-or-regions", |
| 142 | + "--show-branches=count", |
| 143 | + "--show-expansions", |
| 144 | + &format!("--instr-profile={}", profdata_file.display()), |
| 145 | + ]) |
| 146 | + .arg(fuzz_exe) |
| 147 | + .stdout(Stdio::from(cov_file)) |
| 148 | + .spawn() |
| 149 | + .expect("Failed to execute llvm-cov") |
| 150 | + .wait() |
| 151 | + .expect("Failed to execute llvm-cov") |
| 152 | + .success(); |
| 153 | + if !passed { |
| 154 | + panic!("Failed to execute llvm-profdata") |
| 155 | + } |
| 156 | + cov_txt_path |
| 157 | + }; |
| 158 | + let check_diff = |a: &Path, b: &Path, err: &str| { |
| 159 | + let same = Command::new(DIFF) |
| 160 | + .arg("--unified") |
| 161 | + .arg(a) |
| 162 | + .arg(b) |
| 163 | + .status() |
| 164 | + .expect("Failed to execute diff command") |
| 165 | + .success(); |
| 166 | + if !same { |
| 167 | + eprintln!(); |
| 168 | + eprintln!("The coverage was not determinstic between runs."); |
| 169 | + eprintln!("{}", err); |
| 170 | + eprintln!("Exiting."); |
| 171 | + exit(1); |
| 172 | + } |
| 173 | + }; |
| 174 | + // First, check that each fuzz input is determinisic running by itself in a process. |
| 175 | + // |
| 176 | + // This can catch issues and isolate where a single fuzz input triggers non-determinism, but |
| 177 | + // all other fuzz inputs are deterministic. |
| 178 | + // |
| 179 | + // Also, This can catch issues where several fuzz inputs are non-deterministic, but the sum of |
| 180 | + // their overall coverage trace remains the same across runs and thus remains undetected. |
| 181 | + for entry in entries { |
| 182 | + let entry = entry.path(); |
| 183 | + assert!(entry.is_file()); |
| 184 | + let cov_txt_base = run_single(0, &entry); |
| 185 | + let cov_txt_repeat = run_single(1, &entry); |
| 186 | + check_diff( |
| 187 | + &cov_txt_base, |
| 188 | + &cov_txt_repeat, |
| 189 | + &format!("The fuzz target input was {}.", entry.display()), |
| 190 | + ); |
| 191 | + } |
| 192 | + // Finally, check that running over all fuzz inputs in one process is deterministic as well. |
| 193 | + // This can catch issues where mutable global state is leaked from one fuzz input execution to |
| 194 | + // the next. |
| 195 | + { |
| 196 | + assert!(corpus_dir.is_dir()); |
| 197 | + let cov_txt_base = run_single(0, &corpus_dir); |
| 198 | + let cov_txt_repeat = run_single(1, &corpus_dir); |
| 199 | + check_diff( |
| 200 | + &cov_txt_base, |
| 201 | + &cov_txt_repeat, |
| 202 | + &format!("All fuzz inputs in {} were used.", corpus_dir.display()), |
| 203 | + ); |
| 204 | + } |
| 205 | + println!("Coverage test passed for {fuzz_target}."); |
| 206 | +} |
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