From 23f6b1af650aa9a0ca6feea72d2b2c4f305d9d4f Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Sat, 28 Feb 2026 20:55:17 -0800
Subject: [PATCH] pkg/afl++: fuzzer takes a file argument

---
 pkg/afl++/afl.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/pkg/afl++/afl.c b/pkg/afl++/afl.c
index 61eb12c4a..9175b4ebd 100644
--- a/pkg/afl++/afl.c
+++ b/pkg/afl++/afl.c
@@ -94,6 +94,29 @@ int main(int argc, char** argv) {
 
   zig_fuzz_init();
 
+  // If a file argument is provided, read it and execute exactly once.
+  if (argc > 1) {
+    FILE* f = fopen(argv[1], "rb");
+    if (!f) {
+      perror(argv[1]);
+      return 1;
+    }
+    fseek(f, 0, SEEK_END);
+    long fsize = ftell(f);
+    fseek(f, 0, SEEK_SET);
+    unsigned char* fbuf = malloc(fsize);
+    if (!fbuf) {
+      perror("malloc");
+      fclose(f);
+      return 1;
+    }
+    size_t nread = fread(fbuf, 1, fsize, f);
+    fclose(f);
+    zig_fuzz_test(fbuf, nread);
+    free(fbuf);
+    return 0;
+  }
+
   // Manual expansion of __AFL_FUZZ_TESTCASE_BUF.
   // Use shared memory buffer if available, otherwise fall back to the
   // static buffer (for standalone/non-AFL execution).