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https://github.com/ghostty-org/ghostty.git
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On macOS 26.4, AFL builds were picking up Nix compiler-wrapper variables and Apple SDK target settings from the shell environment. That caused afl-cc to drive the wrong linker and target configuration, which broke even simple fuzz harness builds. Unset the Nix compiler and linker environment in the fuzz dev shell so AFL++ uses the system or Homebrew Apple toolchain directly. Also force afl-cc to link with lld because the newer Apple linker asserts on the custom sections emitted by AFL's LLVM instrumentation. Finally, pin fuzz-libghostty to the host target so the build does not inherit stray SDK targets from the environment.
67 lines
2.1 KiB
Zig
67 lines
2.1 KiB
Zig
const std = @import("std");
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const builtin = @import("builtin");
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/// Creates a build step that produces an AFL++-instrumented fuzzing
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/// executable.
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///
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/// Returns a `LazyPath` to the resulting fuzzing executable.
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pub fn addInstrumentedExe(
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b: *std.Build,
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obj: *std.Build.Step.Compile,
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) std.Build.LazyPath {
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// Force the build system to produce the binary artifact even though we
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// only consume the LLVM bitcode below. Without this, the dependency
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// tracking doesn't wire up correctly.
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_ = obj.getEmittedBin();
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const pkg = b.dependencyFromBuildZig(
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@This(),
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.{},
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);
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const afl_cc = b.addSystemCommand(&.{
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b.findProgram(&.{"afl-cc"}, &.{}) catch
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@panic("Could not find 'afl-cc', which is required to build"),
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"-O3",
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});
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if (builtin.target.os.tag.isDarwin()) {
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// Apple's newer ld asserts on the custom section names emitted by
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// AFL's LLVM instrumentation when linking our Zig-produced bitcode.
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// lld links the same inputs without issue.
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afl_cc.addArg("-fuse-ld=lld");
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}
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afl_cc.addArg("-o");
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const fuzz_exe = afl_cc.addOutputFileArg(obj.name);
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afl_cc.addFileArg(pkg.path("afl.c"));
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afl_cc.addFileArg(obj.getEmittedLlvmBc());
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return fuzz_exe;
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}
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/// Creates a run step that invokes `afl-fuzz` with the given instrumented
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/// executable, input corpus directory, and output directory.
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///
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/// Returns the `Run` step so callers can wire it into a build step.
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pub fn addFuzzerRun(
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b: *std.Build,
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exe: std.Build.LazyPath,
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corpus_dir: std.Build.LazyPath,
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output_dir: std.Build.LazyPath,
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) *std.Build.Step.Run {
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const run = b.addSystemCommand(&.{
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b.findProgram(&.{"afl-fuzz"}, &.{}) catch
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@panic("Could not find 'afl-fuzz', which is required to run"),
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"-i",
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});
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run.addDirectoryArg(corpus_dir);
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run.addArgs(&.{"-o"});
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run.addDirectoryArg(output_dir);
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run.addArgs(&.{"--"});
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run.addFileArg(exe);
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return run;
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}
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// Required so `zig build` works although it does nothing.
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pub fn build(b: *std.Build) !void {
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_ = b;
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}
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