minor

README.md

@@ -152,7 +152,7 @@ must also be defined. `drchaos/common` exports read/write procs that assist with
 ### Dos and don'ts
 
 - Don't `echo`  in a fuzz target as it slows down execution speed.
-- Prefer `-d:danger|release` for maximum performance.
+- Prefer `-d:danger` for maximum performance.
 - Once you have a crash you can recompile with `-d:debug` and pass the crashing test case as parameter.
 - Use `debugEcho(x)` in a target to print the crashing input.
 - You could compile without sanitizers, AddressSanitizer slows down programs by ~2x, but it's not recommended.

benchmarks/bench_graph.nim

@@ -1,6 +1,6 @@
 # WARNING: This benchmark does not run a complete fuzzing iteration, just the mutator.
 # As such it doesn't account for LibFuzzer's overhead or the efficiency of the cache.
-# Compile with: nim c --mm:arc -d:danger bench_graph.nim
+# Compile with: nim c --mm:arc --threads:off -d:danger bench_graph.nim
 # Then run: perf record -e cycles:pp --call-graph dwarf ./bench_graph
 include examples/fuzz_graph
 

examples/fuzz_matrix.nim

@@ -52,10 +52,10 @@ when isMainModule:
   proc default[M, N: static[int]](_: typedesc[Matrix32[M, N]]): Matrix32[M, N] =
     zeros(M, N, float32)
 
-  func fuzzTarget(x: Matrix32[2, 2]) =
+  func fuzzTarget(x: Matrix32[3, 3]) =
     when defined(dumpFuzzInput): debugEcho(x)
     # Here you could multiply `x` with the identity matrix and make sure it doesn't change.
-    #doAssert x * eye(2, float32) =~ x
+    #doAssert x * eye(3, float32) =~ x
-    doAssert x != eye(2, float32)
+    doAssert x != eye(3, float32)
 
   defaultMutator(fuzzTarget)

examples/fuzz_simple.nim

@@ -0,0 +1,32 @@
+import drchaos
+
+type
+  SampleStruct[T, U] = object
+    x: T
+    y: U
+
+  SampleEnum = enum
+    A, B, C
+
+  SampleCase = object
+    case kind: SampleEnum
+    of A: z: uint16
+    of B: discard
+    of C: x, y: bool
+
+func `==`(a, b: SampleCase): bool =
+  if a.kind != b.kind: return false
+  case a.kind
+  of A: return a.z == b.z
+  of B: return true
+  of C: return a.x == b.x and a.y == b.y
+
+func fuzzTarget(xs: seq[SampleStruct[uint8, SampleCase]]) =
+  if xs.len > 3 and
+      xs[0].x == 100 and (xs[0].y.kind == C and xs[0].y.x == false and xs[0].y.y == true) and
+      xs[1].x == 55 and (xs[1].y.kind == C and xs[1].y.x == true and xs[1].y.y == false) and
+      xs[2].x == 87 and (xs[2].y.kind == C and xs[2].y.x == false and xs[2].y.y == false) and
+      xs[3].x == 24 and (xs[3].y.kind == C and xs[3].y.x == true and xs[3].y.y == true):
+    doAssert false
+
+defaultMutator(fuzzTarget)