From 3a5a2f8204fcd10f71343a0cc5f4320654deca30 Mon Sep 17 00:00:00 2001
From: Chris Allen <cma@bitemyapp.com>
Date: Sat, 27 Dec 2025 13:44:28 -0600
Subject: [PATCH] fuzzers

---
 .gitignore |   1 +
 flake.nix  | 163 ++++++++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 143 insertions(+), 21 deletions(-)

diff --git a/.gitignore b/.gitignore
index ea2cd7ba..f626a59b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -89,3 +89,4 @@ subprojects/*
 Irssi-Dist
 setup.cfg
 *.egg-info
+result
diff --git a/flake.nix b/flake.nix
index a616b077..93edcc41 100644
--- a/flake.nix
+++ b/flake.nix
@@ -29,6 +29,72 @@
           perl
         ];
 
+        # Build fuzzers with clang and libfuzzer
+        # sanitizers: list of sanitizers to enable (e.g., ["address" "undefined"])
+        mkFuzzerPackage = { sanitizers ? [ "address" "undefined" ] }:
+          let
+            # Use clang's stdenv for libfuzzer support
+            clangStdenv = pkgs.llvmPackages.stdenv;
+
+            # Build sanitizer flags for linking (includes fuzzer)
+            sanitizerFlags = pkgs.lib.concatMapStringsSep "," (s: s) sanitizers;
+            fullSanitizerFlags =
+              if sanitizers == [] then "-fsanitize=fuzzer"
+              else "-fsanitize=fuzzer,${sanitizerFlags}";
+
+            # Compile-time sanitizer flags (without fuzzer - meson adds fuzzer-no-link)
+            compileSanitizerFlags =
+              if sanitizers == [] then ""
+              else "-fsanitize=${sanitizerFlags}";
+          in
+          clangStdenv.mkDerivation {
+            pname = "irssi-fuzz";
+            version = "1.5-head";
+
+            src = ./.;
+
+            nativeBuildInputs = with pkgs; [
+              meson
+              ninja
+              pkg-config
+              perl  # Needed at build time for generating help files
+            ];
+
+            buildInputs = with pkgs; [
+              glib
+              openssl
+              ncurses
+            ];
+
+            # Use preConfigure to set CFLAGS/LDFLAGS since meson's -Dc_args
+            # breaks the initial compiler test when sanitizers are involved
+            preConfigure = pkgs.lib.optionalString (sanitizers != []) ''
+              export CFLAGS="-g -O1 -fno-omit-frame-pointer ${compileSanitizerFlags}"
+              export LDFLAGS="${compileSanitizerFlags}"
+            '';
+
+            mesonFlags = [
+              "-Dwith-perl=no"
+              "-Dwithout-textui=yes"
+              "-Dwith-fuzzer=yes"
+              "-Dwith-fuzzer-lib=${fullSanitizerFlags}"
+              "-Dfuzzer-link-language=c"
+            ];
+
+            # Only install the fuzzer binaries
+            postInstall = ''
+              # Remove non-fuzzer files if any were installed
+              rm -rf $out/share $out/include $out/lib/pkgconfig || true
+            '';
+
+            meta = with pkgs.lib; {
+              description = "Irssi fuzz testing targets built with libFuzzer";
+              homepage = "https://irssi.org/";
+              license = licenses.gpl2Plus;
+              platforms = platforms.unix;
+            };
+          };
+
       in
       {
         packages = {
@@ -87,32 +153,87 @@
               platforms = platforms.unix;
             };
           };
+
+          # Fuzzers with AddressSanitizer + UndefinedBehaviorSanitizer (recommended)
+          fuzz = mkFuzzerPackage {
+            sanitizers = [ "address" "undefined" ];
+          };
+
+          # Fuzzers with only AddressSanitizer (faster, catches memory errors)
+          fuzz-asan = mkFuzzerPackage {
+            sanitizers = [ "address" ];
+          };
+
+          # Fuzzers with only UndefinedBehaviorSanitizer
+          fuzz-ubsan = mkFuzzerPackage {
+            sanitizers = [ "undefined" ];
+          };
         };
 
-        devShells.default = pkgs.mkShell {
-          name = "irssi-dev";
+        devShells = {
+          default = pkgs.mkShell {
+            name = "irssi-dev";
 
-          inherit buildInputs;
+            inherit buildInputs;
 
-          nativeBuildInputs = nativeBuildInputs ++ (with pkgs; [
-            # Additional development tools
-            gdb
-            valgrind
-          ] ++ pkgs.lib.optionals pkgs.stdenv.isLinux [
-            strace
-          ]);
+            nativeBuildInputs = nativeBuildInputs ++ (with pkgs; [
+              # Additional development tools
+              gdb
+              valgrind
+            ] ++ pkgs.lib.optionals pkgs.stdenv.isLinux [
+              strace
+            ]);
 
-          shellHook = ''
-            echo "Irssi development environment"
-            echo ""
-            echo "Build commands:"
-            echo "  meson setup Build"
-            echo "  ninja -C Build"
-            echo ""
-            echo "Run tests:"
-            echo "  ninja -C Build test"
-            echo ""
-          '';
+            shellHook = ''
+              echo "Irssi development environment"
+              echo ""
+              echo "Build commands:"
+              echo "  meson setup Build"
+              echo "  ninja -C Build"
+              echo ""
+              echo "Run tests:"
+              echo "  ninja -C Build test"
+              echo ""
+            '';
+          };
+
+          # Development shell for fuzzing
+          fuzz = pkgs.mkShell.override { stdenv = pkgs.llvmPackages.stdenv; } {
+            name = "irssi-fuzz-dev";
+
+            buildInputs = with pkgs; [
+              glib
+              openssl
+              ncurses
+            ];
+
+            nativeBuildInputs = with pkgs; [
+              meson
+              ninja
+              pkg-config
+              perl
+              # Fuzzing tools
+              llvmPackages.llvm  # For llvm-symbolizer, llvm-cov, etc.
+            ];
+
+            shellHook = ''
+              echo "Irssi fuzzing development environment (clang + libFuzzer)"
+              echo ""
+              echo "Build fuzzers:"
+              echo "  meson setup Build-fuzz -Dwith-perl=no -Dwithout-textui=yes -Dwith-fuzzer=yes"
+              echo "  ninja -C Build-fuzz"
+              echo ""
+              echo "Fuzz targets will be in Build-fuzz/src/fe-fuzz/:"
+              echo "  - irssi-fuzz"
+              echo "  - server-fuzz"
+              echo "  - event-get-params-fuzz (in irc/core/)"
+              echo "  - theme-load-fuzz (in fe-common/core/)"
+              echo ""
+              echo "Run a fuzzer:"
+              echo "  ./Build-fuzz/src/fe-fuzz/irssi-fuzz corpus/"
+              echo ""
+            '';
+          };
         };
       }
     );